WorldWideScience

Sample records for anisotropy energy spectrum

  1. Supernovae anisotropy power spectrum

    CERN Document Server

    Ghodsi, Hoda; Habibi, Farhang

    2016-01-01

    We contribute another anisotropy study to this field of research using Supernovae Type Ia (SNe Ia). In this work, we utilise the power spectrum calculation method and apply it to both the current SNe Ia data and simulation. Our simulations are constructed with the characteristics of the upcoming survey of the Large Synoptic Survey Telescope (LSST), which shall bring us the largest SNe Ia collection to date. We make predictions for the amplitude of a possible dipole anisotropy or anisotropy in higher multipole moments that would be detectable by the LSST.

  2. Effects of anisotropy on the frequency spectrum of gravity waves observed by MST radar

    Science.gov (United States)

    Liu, C. H.

    1986-01-01

    In the investigation of gravity waves using mesosphere-stratosphere-troposphere radar data, model gravity-wave spectra have been used. In these model spectra, one usually assumes azimuthal symmetry. The effect of spectral anisotropy on the observed spectrum is studied here. It is shown that for a general Garrett-Munk-type spectrum, the anisotropy does not affect the frequency spectrum observed by the vertically beamed radar. For the oblique beam, however, the observed frequency spectrum is changed. A general gravity wave spectrum including azimuthal anisotropy is considered.

  3. Implications of the cosmic ray electron spectrum and anisotropy measured with Fermi-LAT

    International Nuclear Information System (INIS)

    The Fermi Large Area Telescope (LAT) collaboration recently released the updated results of the measurement of the cosmic ray electron (CRE) spectrum and published its first constraints on the CRE anisotropy. With respect to the previous Fermi-LAT results, the CRE spectrum measurement was extended down from 20 to 7 GeV, thus providing a better lever arm to discriminate theoretical models. Here we show that the new data strengthen the evidence for the presence of two distinct electron and positron spectral components. Furthermore, we show that under such hypothesis most relevant CRE and positron data sets are remarkably well reproduced. Consistent fits of cosmic-ray nuclei and antiproton data, which are crucial to validate the adopted propagation setup(s) and to fix the solar modulation potential, are obtained for the Kraichnan and plain-diffusion propagation setups, while the Kolmogorov one is disfavored. We then confirm that nearby pulsars are viable source candidates of the required e± extra-component. In that case, we show that the predicted CRE anisotropy is compatible with Fermi-LAT constraints and that a positive detection should be at hand of that observatory. Models assuming that only nearby supernova remnants contribute to the high energy tail of the observed CRE spectrum are in contrast with anisotropy limits. (orig.)

  4. Spectrum and anisotropy of the cosmic infrared background

    Science.gov (United States)

    Bond, J. R.; Carr, B. J.; Hogan, C. J.

    1986-01-01

    If the luminosity per mass of the universe at redshifts z = 5-1000 were at least comparable to its present luminosity, then a conspicuous cosmological infrared radiation background would be produced. A number of situations where this could arise are surveyed, and the intensity of the background is evaluated for specific types of sources (protogalaxies, pregalactic stars, quasars, black holes, and decaying relict particles) in several candidate scenarios, which are also discussed in terms of metal enrichment, dark matter, and formation of large-scale structure. The spectrum of the background radiation is estimated, both with and without dust obscuration. General features of cosmological radiative transfer with dust are discussed. It is argued that dust is expected to degrade the background to the far-infrared, 100-1000 microns, where the wavelength of the spectral peak can be predicted from the total present-day background flux and depends only weakly on properties of the dust or the redshift of emission. The statistical properties of the anisotropy expected in the radiation and its relationship to the distribution of dust at the time the dust is formed or the radiation is produced are estimated. Intensity fluctuations at the few percent level on arc minute scales are typical in current galaxy-formation scenarios.

  5. CMB anisotropy induced by tachyonic perturbations of dark energy

    CERN Document Server

    Libanov, M V; Sazhina, O S; Sazhin, M V

    2008-01-01

    We study effects of possible tachyonic perturbations of dark energy on the CMB temperature anisotropy. Motivated by some models of phantom energy, we consider both Lorentz-invariant and Lorentz-violating dispersion relations for tachyonic perturbations. We show that in the Lorentz-violating case, the shape of the CMB anisotropy spectrum generated by the tachyonic perturbations is very different from that due to adiabatic scalar perturbations and, if sizeable, it would be straightforwardly distinguished from the latter. The tachyonic contribution improves slightly the agreement between the theory and data; however, this improvement is not statistically significant, so our analysis results in limits on the time scale of the tachyonic instability. In the Lorentz-invariant case, tachyonic contribution is a rapidly decaying function of the multipole number $l$, so that the entire observed dipole can be generated without conflicting the data at higher multipoles. On the conservative side, our comparison with the da...

  6. Negative dependence of surface magnetocrystalline anisotropy energy on film thickness in Co33Fe67 alloy

    Science.gov (United States)

    Wang, De-Lai; Cui, Ming-Qi; Yang, Dong-Liang; Dong, Jun-Cai; Xu, Wei

    2016-10-01

    In this work, the magnetocrystalline anisotropy energy (MAE) on the surface of Fe33Co67 alloy film is extracted from x-ray magnetic linear dichroism (XMLD) experiments. The result indicates that the surface MAE value is negatively correlated with thickness. Through spectrum calculations and analysis, we find that besides the thickness effect, another principal possible cause may be the shape anisotropy resulting from the presence of interface roughness. These two factors lead to different electron structures on the fermi surface with different exchange fields, which produces different spin-orbit interaction anisotropies. Project supported by the National Natural Science Foundation of China (Grant Nos. 11075176 and 11375131).

  7. CMB anisotropy due to filamentary gas: power spectrum and cosmological parameter bias

    Energy Technology Data Exchange (ETDEWEB)

    Shimon, Meir; Sadeh, Sharon; Rephaeli, Yoel, E-mail: meirs@wise.tau.ac.il, E-mail: shrs@post.tau.ac.il, E-mail: yoelr@wise.tau.ac.il [School of Physics and Astronomy, Tel Aviv University, Tel Aviv 69978 (Israel)

    2012-10-01

    Hot gas in filamentary structures induces CMB aniostropy through the SZ effect. Guided by results from N-body simulations, we model the morphology and gas properties of filamentary gas and determine the power spectrum of the anisotropy. Our treatment suggests that power levels can be an appreciable fraction of the cluster contribution at multipoles l∼<1500. Its spatially irregular morphology and larger characteristic angular scales can help to distinguish this SZ signature from that of clusters. In addition to intrinsic interest in this most extended SZ signal as a probe of filaments, its impact on cosmological parameter estimation should also be assessed. We find that filament 'noise' can potentially bias determination of A{sub s}, n{sub s}, and w (the normalization of the primordial power spectrum, the scalar index, and the dark energy equation of state parameter, respectively) by more than the nominal statistical uncertainty in Planck SZ survey data. More generally, when inferred from future optimal cosmic-variance-limited CMB experiments, we find that virtually all parameters will be biased by more than the nominal statistical uncertainty estimated for these next generation CMB experiments.

  8. Anisotropy vs chemical composition at ultra-high energies

    CERN Document Server

    Lemoine, Martin

    2009-01-01

    This paper proposes and discusses a test of the chemical composition of ultra-high energy cosmic rays that relies on the anisotropy patterns measured as a function of energy. In particular, we show that if one records an anisotropy signal produced by heavy nuclei of charge Z above an energy E_{thr}, one should record an even stronger (possibly much stronger) anisotropy at energies >E_{thr}/Z due to the proton component that is expected to be associated with the sources of the heavy nuclei. This conclusion remains robust with respect to the parameters characterizing the sources and it does not depend at all on the modelling of astrophysical magnetic fields. As a concrete example, we apply this test to the most recent data of the Pierre Auger Observatory. Assuming that the anisotropy reported above 55EeV is not a statistical accident, and that no significant anisotropy has been observed at energies 10^{45}Z^{-2}erg/s. Using this bound in conjunction with the above conclusions, we argue that the current PAO data...

  9. The CMB Power Spectrum from the Background Emission Anisotropy Scanning Telescope (BEAST) Experiment

    CERN Document Server

    O'Dwyer, I J; Childers, J; Figueiredo, N; Halevi, D; Huey, G G; Lubin, P M; Maino, D; Mandolesi, N; Marvil, J; Meinhold, P R; Mejia, J; Natoli, P; O'Neill, H; Pina, A; Seiffert, M D; Stebor, N C; Tello, C A S; Villela, T; Wandelt, B D; Williams, B; Wünsche, C A; Dwyer, Ian J. O'; Bersanelli, Marco; Childers, Jeffrey; Figueiredo, Newton; Halevi, Doron; Huey, Gregory G.; Lubin, Philip M.; Maino, Davide; Mandolesi, Nazzareno; Marvil, Joshua; Meinhold, Peter R.; Mejia, Jorge; Natoli, Paolo; Neill, Hugh O'; Pina, Agenor; Seiffert, Michael D.; Stebor, Nathan C.; Tello, Camilo; Villela, Thyrso; Wandelt, Benjamin D.; Williams, Brian; Wuensche, Carlos Alexandre

    2003-01-01

    The Background Emission Anisotropy Scanning Telescope (BEAST) is a 2.2m off-axis telescope with an 8 element mixed Q (38-45GHz) and Ka (26-36GHz) band focal plane, designed for balloon borne and ground based studies of the Cosmic Microwave Background. Here we present the Cosmic Microwave Background (CMB) angular power spectrum calculated from 682 hours of data observed with the BEAST instrument. We use a binned pseudo-Cl estimator (the MASTER method). We find results that are consistent with other determinations of the CMB anisotropy for angular wavenumber l between 100 and 600. We also perform cosmological parameter estimation. The BEAST data alone produces a good constraint on Omega_k = 1-Omega_tot=-0.074 +/- 0.070, consistent with a flat Universe. A joint parameter estimation analysis with a number of previous CMB experiments produces results consistent with previous determinations.

  10. New estimation of the spectral index of high-energy cosmic rays as determined by the Compton-Getting anisotropy

    CERN Document Server

    Amenomori, M; Chen, D; Cui, S W; Danzengluobu,; Ding, L K; Ding, X H; Fan, C; Feng, C F; Feng, Zhaoyang; Feng, Z Y; Gao, X Y; Geng, Q X; Guo, H W; He, H H; He, M; Hibino, K; Hotta, N; Hu, Haibing; Hu, H B; Huang, J; Huang, Q; Jia, H Y; Kajino, F; Kasahara, K; Katayose, Y; Kato, C; Kawata, K; Labaciren,; Le, G M; Li, A F; Li, J Y; Lou, Y -Q; Lü, H; Lu, S L; Meng, X R; Mizutani, K; Mu, J; Munakata, K; Nagai, A; Nanjo, H; Nishizawa, M; Ohnishi, M; Ohta, I; Onuma, H; Ouchi, T; Ozawa, S; Ren, J R; Saitô, T; Saito, T Y; Sakata, M; Sako, T K; Shibata, M; Shiomi, A; Shirai, T; Sugimoto, H; Takita, M; Tan, Y H; Tateyama, N; Torii, S; Tsuchiya, H; Udo, S; Wang, B; Wang, H; Wang, X; Wang, Y; Wang, Y G; Wu, H R; Xue, L; Yamamoto, Y; Yan, C T; Yang, X C; Yasue, S; Ye, Z H; Yu, G C; Yuan, A F; Yuda, T; Zhang, H M; Zhang, J L; Zhang, N J; Zhang, X Y; Zhang, Y; Zhang, Yi; Zhaxisangzhu,; Zhou, X X

    2007-01-01

    The amplitude of the Compton-Getting (CG) anisotropy contains the power-law index of the cosmic-ray energy spectrum. Based on this relation and using the Tibet air-shower array data, we measure the cosmic-ray spectral index to be $-3.03 \\pm 0.55_{stat} \\pm < 0.62_{syst}$ between 6 TeV and 40 TeV, consistent with $-$2.7 from direct energy spectrum measurements. Potentially, this CG anisotropy analysis can be utilized to confirm the astrophysical origin of the ``knee'' against models for non-standard hadronic interactions in the atmosphere.

  11. Microwave background anisotropies and the primordial spectrum of cosmological density fluctuations

    International Nuclear Information System (INIS)

    Microwave background anisotropies in various cosmological scenarios are studied. In particular, we examine the extent to which non-scale invariant spectra of the primordial density fluctuations are consistent with the observational upper limits. The resultant constraints are summarized as contours on (n, Ω) plane, where n is the power-law index of the primordial spectrum of density fluctuations, and Ω is the cosmological density parameter. They are compared also with the constraints from the cosmic Mach number test, recently proposed by Ostriker and Suto. The parameter regions which pass both tests are not consistent with the theoretical prejudice inspired by the inflationary model. (author)

  12. The CMB Power Spectrum from the Background Emission Anisotropy Scanning Telescope (BEAST) Experiment

    OpenAIRE

    O'Dwyer, Ian J.; Bersanelli, Marco; Childers, Jeffrey; Figueiredo, Newton; Halevi, Doron; Huey, Gregory G.; Lubin, Philip M.; Maino, Davide; Mandolesi, Nazzareno; Marvil, Joshua; Meinhold, Peter R.; Mejia, Jorge; Natoli, Paolo; O'Neill, Hugh,; Pina, Agenor

    2003-01-01

    The Background Emission Anisotropy Scanning Telescope (BEAST) is a 2.2m off-axis telescope with an 8 element mixed Q (38-45GHz) and Ka (26-36GHz) band focal plane, designed for balloon borne and ground based studies of the Cosmic Microwave Background. Here we present the Cosmic Microwave Background (CMB) angular power spectrum calculated from 682 hours of data observed with the BEAST instrument. We use a binned pseudo-Cl estimator (the MASTER method). We find results that are consistent with ...

  13. Spectrum and Anisotropy of Turbulence from Multi-Frequency Measurement of Synchrotron Polarization

    CERN Document Server

    Lazarian, Alex

    2015-01-01

    We consider turbulent synchrotron emitting media that also exhibits Faraday rotation and provide a statistical description of synchrotron polarization fluctuations. In particular, we consider these fluctuations as a function of the spatial separation of the direction of measurements and as a function of wavelength for the same line-of-sight. On the basis of our general analytical approach, we introduce several measures that can be used to obtain the spectral slopes and correlation scales of both the underlying magnetic turbulence responsible for emission and the spectrum of the Faraday rotation fluctuations. We show the synergetic nature of these measures and discuss how the study can be performed using sparsely sampled interferometric data. We also discuss how additional characteristics of turbulence can be obtained, including the turbulence anisotropy, the three dimensional direction of the mean magnetic field. We consider both cases when the synchrotron emission and Faraday rotation regions coincide and wh...

  14. New Estimation of the Spectral Index of High-Energy Cosmic Rays as Determined by the Compton-Getting Anisotropy

    Science.gov (United States)

    Amenomori, M.; Bi, X. J.; Chen, D.; Cui, S. W.; Danzengluobu; Ding, L. K.; Ding, X. H.; Fan, C.; Feng, C. F.; Feng, Zhaoyang; Feng, Z. Y.; Gao, X. Y.; Geng, Q. X.; Guo, H. W.; He, H. H.; He, M.; Hibino, K.; Hotta, N.; Hu, Haibing; Hu, H. B.; Huang, J.; Huang, Q.; Jia, H. Y.; Kajino, F.; Kasahara, K.; Katayose, Y.; Kato, C.; Kawata, K.; Labaciren; Le, G. M.; Li, A. F.; Li, J. Y.; Lou, Y.-Q.; Lu, H.; Lu, S. L.; Meng, X. R.; Mizutani, K.; Mu, J.; Munakata, K.; Nagai, A.; Nanjo, H.; Nishizawa, M.; Ohnishi, M.; Ohta, I.; Onuma, H.; Ouchi, T.; Ozawa, S.; Ren, J. R.; Saito, T.; Saito, T. Y.; Sakata, M.; Sako, T. K.; Shibata, M.; Shiomi, A.; Shirai, T.; Sugimoto, H.; Takita, M.; Tan, Y. H.; Tateyama, N.; Torii, S.; Tsuchiya, H.; Udo, S.; Wang, B.; Wang, H.; Wang, X.; Wang, Y.; Wang, Y. G.; Wu, H. R.; Xue, L.; Yamamoto, Y.; Yan, C. T.; Yang, X. C.; Yasue, S.; Ye, Z. H.; Yu, G. C.; Yuan, A. F.; Yuda, T.; Zhang, H. M.; Zhang, J. L.; Zhang, N. J.; Zhang, X. Y.; Zhang, Y.; Zhang, Yi; Zhaxisangzhu; Zhou, X. X.; Tibet ASγ Collaboration

    2008-01-01

    The amplitude of the Compton-Getting (CG) anisotropy contains the power-law index of the cosmic-ray energy spectrum. Based on this relation and using the Tibet air shower array data, we measure the cosmic-ray spectral index to be -3.03 ± 0.55stat ± analysis can be utilized to confirm the astrophysical origin of the "knee" against models for nonstandard hadronic interactions in the atmosphere.

  15. Constraints on the High-l Power Spectrum of Millimeter-wave Anisotropies from APEX-SZ

    CERN Document Server

    Reichardt, C L; Ade, P A R; Basu, K; Bender, A N; Bertoldi, F; Cho, H -M; Chon, G; Dobbs, M; Ferrusca, D; Halverson, N W; Holzapfel, W L; Horellou, C; Johansson, D; Johnson, B R; Kennedy, J; Kneissl, R; Lanting, T; Lee, A T; Lueker, M; Mehl, J; Menten, K M; Nord, M; Pacaud, F; Richards, P L; Schaaf, R; Schwan, D; Spieler, H; Weiss, A; Westbrook, B

    2009-01-01

    We present measurements of the angular power spectrum of millimeter wave anisotropies with the APEX-SZ instrument. APEX-SZ has mapped 0.8 square degrees of sky at a frequency of 150 GHz with an angular resolution of 1'. These new measurements significantly improve the power constraints at 150 GHz over the range of angular multipoles 3000 < l < 10,000, limiting the total astronomical anisotropy in a flat band power to be less than 105 microK^2 at 95% CL. We expect both submillimeter-bright, dusty galaxies and secondary CMB anisotropies from the Sunyaev-Zel'dovich effect (SZE) to significantly contribute to the observed power. Subtracting the SZE power spectrum expected for sigma_8=0.8 and masking bright sources, the best fit value for the remaining power is C_l = 1.1^{+0.9}_{-0.8} x 10^{-5} micro K^2 (1.7^{+1.4}_{-1.3} Jy^2 sr^{-1}). This agrees well with model predictions for power due to submillimeter-bright, dusty galaxies. Simultaneously fitting for the amplitude of the SZE power spectrum and a Poiss...

  16. ANISOTROPY OF (1× 1)-SURFACE FREE ENERGIES OF CRYSTALS

    Institute of Scientific and Technical Information of China (English)

    Z.M.Yu; A. Flodstrom

    2001-01-01

    The surface free energy (SFE) of (1× 1)-surfaces of crystals, without reconstructionand adsorption, is calculated using a bond-broken mode. In the mode, the potentialenergy of the crystals is treated as a sum of the energies of the bonds connectingpair-wise atoms (u-bonds). The SFE is calculated based on the bond energy and thearea density of dangling bonds which depends on the structure of the surface. Theresults provide a general expression for the SFE in terms of the bond energy (E)and the bond length (do) of the crystal and Miller indices hkl. The anisotropy ofthe SFE is therefore completely determined with the expression. As the examples,considering the nearest-neighboring bonding, the SFEs of sc, fcc, bcc and cth (cubictetrahedral) crystals are discussed, respectively. Wulff plots of bcc and fcc crystalsare then obtained. The equilibrium forms (EFs) of these crystals ave consequentlygot from their Wulff plots, respectively. It is found that the EFs of bcc and fcc arerespectively the rhombic dodecahedron and the truncated-octahedron that are their firstBrillouin zones, respectively.

  17. Anisotropy in the cosmic radiation at TeV energy

    CERN Document Server

    Iuppa, Roberto

    2013-01-01

    In recent years very important results were obtained from cosmic ray experiments about the arrival direction distribution of primaries in the TeV energy range. As most of these particles are charged nuclei, they are deflected by the magnetic field they pass through before reaching the Earth surface, the effect of the Lorentz force being inversely proportional to the particle energy. As far as the local interstellar medium is known, the gyroradius of a 10 TeV proton is expected to be only 100 a.u., small enough to make the arrival direction distribution isotropic. Since 1930s a "large scale" (90{\\deg}-120{\\deg}) anisotropy is known to exist, generally interpreted as the combined effect of sources far away and magnetic fields nearby. Nonetheless, in the last decade experiments like Tibet-ASg, Milagro, ARGO-YBJ and IceCube discovered structures as wide as 10{\\deg}-30{\\deg} all over the sky at ~ 10 TeV energy, what is unexplainable within the standard model of cosmic rays. In this paper a review of the most recen...

  18. Collision-induced Raman scattering and the peculiar case of neon: Anisotropic spectrum, anisotropy, and the inverse scattering problem

    Energy Technology Data Exchange (ETDEWEB)

    Dixneuf, Sophie [Forschungszentrum Jülich GmbH IEK-8: Troposphere, 52425 Jülich (Germany); Rachet, Florent; Chrysos, Michael, E-mail: michel.chrysos@univ-angers.fr [LUNAM Université, Université d’Angers, CNRS UMR 6200, Laboratoire MOLTECH-Anjou, 2 Bd Lavoisier, 49045 Angers (France)

    2015-02-28

    Owing in part to the p orbitals of its filled L shell, neon has repeatedly come on stage for its peculiar properties. In the context of collision-induced Raman spectroscopy, in particular, we have shown, in a brief report published a few years ago [M. Chrysos et al., Phys. Rev. A 80, 054701 (2009)], that the room-temperature anisotropic Raman lineshape of Ne–Ne exhibits, in the far wing of the spectrum, a peculiar structure with an aspect other than a smooth wing (on a logarithmic plot) which contrasts with any of the existing studies, and whose explanation lies in the distinct way in which overlap and exchange interactions interfere with the classical electrostatic ones in making the polarizability anisotropy, α{sub ∥} − α{sub ⊥}. Here, we delve deeper into that study by reporting data for that spectrum up to 450 cm{sup −1} and for even- and odd-order spectral moments up to M{sub 6}, as well as quantum lineshapes, generated from SCF, CCSD, and CCSD(T) models for α{sub ∥} − α{sub ⊥}, which are critically compared with the experiment. On account of the knowledge of the spectrum over the augmented frequency domain, we show how the inverse scattering problem can be tackled both effectively and economically, and we report an analytic function for the anisotropy whose quantum lineshape faithfully reproduces our observations.

  19. Collision-induced Raman scattering and the peculiar case of neon: anisotropic spectrum, anisotropy, and the inverse scattering problem.

    Science.gov (United States)

    Dixneuf, Sophie; Rachet, Florent; Chrysos, Michael

    2015-02-28

    Owing in part to the p orbitals of its filled L shell, neon has repeatedly come on stage for its peculiar properties. In the context of collision-induced Raman spectroscopy, in particular, we have shown, in a brief report published a few years ago [M. Chrysos et al., Phys. Rev. A 80, 054701 (2009)], that the room-temperature anisotropic Raman lineshape of Ne-Ne exhibits, in the far wing of the spectrum, a peculiar structure with an aspect other than a smooth wing (on a logarithmic plot) which contrasts with any of the existing studies, and whose explanation lies in the distinct way in which overlap and exchange interactions interfere with the classical electrostatic ones in making the polarizability anisotropy, α∥ - α⊥. Here, we delve deeper into that study by reporting data for that spectrum up to 450 cm(-1) and for even- and odd-order spectral moments up to M6, as well as quantum lineshapes, generated from SCF, CCSD, and CCSD(T) models for α∥ - α⊥, which are critically compared with the experiment. On account of the knowledge of the spectrum over the augmented frequency domain, we show how the inverse scattering problem can be tackled both effectively and economically, and we report an analytic function for the anisotropy whose quantum lineshape faithfully reproduces our observations.

  20. Ultra Low Energy Switching of Ferromagnet with Perpendicular Anisotropy on Topological Insulator by Voltage Controlled Magnetic Anisotropy

    Science.gov (United States)

    Ghosh, Bahniman; Pramanik, Tanmoy; Dey, Rik; Roy, Urmimala; Register, Leonard; Banerjee, Sanjay

    2015-03-01

    We propose and demonstrate, through simulation, an ultra low energy memory device on a topological insulator thin film. The device consists of a thin layer of Fe deposited on the surface of a topological insulator, Bi2Se3. The top surface of Fe is covered with MgO so that the ferromagnetic layer has perpendicular anisotropy. Current is passed on the surface of the topological insulator which switches the magnetization of the Fe ferromagnet through strong exchange interaction, between electrons contributing to the surface current on the Bi2Se3 and the d electrons in the ferromagnet, and spin transfer torque due to shunting of current through the ferromagnet. Voltage controlled magnetic anisotropy enables ultra low energy switching. Our micromagnetic simulations, predict switching time of the order of 2.4 ns and switching energy of the order of 0.16 fJ for a ferromagnetic bit with thermal stability of 90 kBT. The proposed structure combines the advantages of both large spin torque from topological insulators and those of perpendicular anisotropy materials. This work is supported by NRI SWAN and NSF NASCENT Center.

  1. Energy spectrum of C60 fullerene

    Science.gov (United States)

    Mironov, G. I.; Murzashev, A. I.

    2011-11-01

    The energy spectrum of the C60 fullerene has been calculated in terms of the Shubin-Vonsovskii-Hubbard model using an approximation of static fluctuations. Based on the spectrum, the optical absorption bands at 4.84, 5.88, and 6.30 eV observed experimentally have been successfully explained. It has been concluded that the model used is applicable for the calculation of the energy spectrum and the energy properties of other nanosystems, such as fullerenes of higher orders, carbon nanotubes, and grafen planes.

  2. CONSTRAINTS ON THE SOURCE OF ULTRA-HIGH-ENERGY COSMIC RAYS USING ANISOTROPY VERSUS CHEMICAL COMPOSITION

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Ruo-Yu; Wang, Xiang-Yu [School of Astronomy and Space Science, Nanjing University, Nanjing 210093 (China); Taylor, Andrew M. [Dublin Institute for Advanced Studies, 31 Fitzwilliam Place, Dublin 2 (Ireland); Lemoine, Martin [Institut d' Astrophysique de Paris, CNRS, UPMC, 98 bis Boulevard Arago, F-75014 Paris (France); Waxman, Eli, E-mail: lemoine@iap.fr [Physics Faculty, Weizmann Institute, P.O. Box 26, Rehovot 7600 (Israel)

    2013-10-20

    The joint analysis of anisotropy signals and chemical composition of ultra-high-energy cosmic rays offers strong potential for shedding light on the sources of these particles. Following up on an earlier idea, this paper studies the anisotropies produced by protons of energy >E/Z, assuming that anisotropies at energy >E have been produced by nuclei of charge Z, which share the same magnetic rigidity. We calculate the number of secondary protons produced through photodisintegration of the primary heavy nuclei. Making the extreme assumption that the source does not inject any proton, we find that the source(s) responsible for anisotropies such as reported by the Pierre Auger Observatory should lie closer than ∼20-30, 80-100, and 180-200 Mpc if the anisotropy signal is mainly composed of oxygen, silicon, and iron nuclei, respectively. A violation of this constraint would otherwise result in the secondary protons forming a more significant anisotropy signal at lower energies. Even if the source were located closer than this distance, it would require an extraordinary metallicity ∼> 120, 1600, and 1100 times solar metallicity in the acceleration zone of the source, for oxygen, silicon, and iron, respectively, to ensure that the concomitantly injected protons do not produce a more significant low-energy anisotropy. This offers interesting prospects for constraining the nature and the source of ultra-high-energy cosmic rays with the increase in statistics expected from next-generation detectors.

  3. Energy Spectrum of Buoyancy-Driven Turbulence

    OpenAIRE

    Kumar, Abhishek; Chatterjee, Anando G.; Verma, Mahendra K.

    2014-01-01

    Using high-resolution direct numerical simulation and arguments based on the kinetic energy flux $\\Pi_u$, we demonstrate that for stably stratified flows, the kinetic energy spectrum $E_u(k) \\sim k^{-11/5}$, the entropy spectrum $E_\\theta(k) \\sim k^{-7/5}$, and $\\Pi_u(k) \\sim k^{-4/5}$, consistent with the Bolgiano-Obukhov scaling. This scaling arises due to the conversion of kinetic energy to the potential energy by buoyancy. For weaker buoyancy, this conversion is weak, hence $E_u(k)$ follo...

  4. EVOLUTION OF THE COSMIC MICROWAVE BACKGROUND POWER SPECTRUM ACROSS WILKINSON MICROWAVE ANISOTROPY PROBE DATA RELEASES: A NONPARAMETRIC ANALYSIS

    International Nuclear Information System (INIS)

    Using a nonparametric function estimation methodology, we present a comparative analysis of the Wilkinson Microwave Anisotropy Probe (WMAP) 1-, 3-, 5-, and 7-year data releases for the cosmic microwave background (CMB) angular power spectrum with respect to the following key questions. (1) How well is the power spectrum determined by the data alone? (2) How well is the ΛCDM model supported by a model-independent, data-driven analysis? (3) What are the realistic uncertainties on peak/dip locations and heights? Our results show that the height of the power spectrum is well determined by data alone for multipole l approximately less than 546 (1-year), 667 (3-year), 804 (5-year), and 842 (7-year data). We show that parametric fits based on the ΛCDM model are remarkably close to our nonparametric fits in l-regions where data are sufficiently precise. In contrast, the power spectrum for an HΛCDM model is progressively pushed away from our nonparametric fit as data quality improves with successive data realizations, suggesting incompatibility of this particular cosmological model with respect to the WMAP data sets. We present uncertainties on peak/dip locations and heights at the 95% (2σ) level of confidence and show how these uncertainties translate into hyperbolic 'bands' on the acoustic scale (lA ) and peak shift (φm) parameters. Based on the confidence set for the 7-year data, we argue that the low-l upturn in the CMB power spectrum cannot be ruled out at any confidence level in excess of about 10% (≈0.12σ). Additional outcomes of this work are a numerical formulation for minimization of a noise-weighted risk function subject to monotonicity constraints, a prescription for obtaining nonparametric fits that are closer to cosmological expectations on smoothness, and a method for sampling cosmologically meaningful power spectrum variations from the confidence set of a nonparametric fit.

  5. Constraints on the source of ultra-high energy cosmic rays using anisotropy vs chemical composition

    CERN Document Server

    Liu, Ruo-Yu; Lemoine, Martin; Wang, Xiang-Yu; Waxman, Eli

    2013-01-01

    The joint analysis of anisotropy signals and chemical composition of ultra-high energy cosmic rays offers strong potential for shedding light on the sources of these particles. Following up on an earlier idea, this paper studies the anisotropies produced by protons of energy >E/Z, assuming that anisotropies at energy >E have been produced by nuclei of charge Z, which share the same magnetic rigidity. We calculate the number of secondary protons produced through photodisintegration of the primary heavy nuclei. Making the extreme assumption that the source does not inject any proton, we find that the source(s) responsible for anisotropies such as reported by the Pierre Auger Observatory should lie closer than ~20-30, 80-100 and 180-200 Mpc if the anisotropy signal is mainly composed of oxygen, silicon and iron nuclei respectively. A violation of this constraint would otherwise result in the secondary protons forming a more significant anisotropy signal at lower energies. Even if the source were located closer t...

  6. Correlated oscillations of the magnetic anisotropy energy and orbital moment anisotropy in thin films: The role of quantum well states

    Science.gov (United States)

    Sandratskii, L. M.

    2015-10-01

    We report the first-principles study of the correlated behavior of the magnetic anisotropy energy (MAE) and orbital moment anisotropy (OMA) as the functions of the thickness N of the Fe film. The work is motivated by recent experimental studies combining photoemission, x-ray magnetic circular dichroism, and magnetic anisotropy measurements. In agreement with experiment, the correlated oscillations of MAE (N ) and OMA (N ) are obtained that have their origin in the formation of the 3d quantum well states (QWS) confined in the films. The main contribution to the oscillation amplitude comes from the surface layer. This is an interesting feature of the phenomenon consisting in the peculiar dependence of the physical quantities on the thickness of the film. We demonstrate that the band structure of the bulk Fe does not reflect adequately the properties of the 3d QWS in thin films and, therefore, does not provide the basis for understanding the oscillations of MAE (N ) and OMA (N ) . A detailed point-by-point analysis in the two-dimensional (2D) Brillouin zone (BZ) of the film shows that the contribution of the Γ point, contrary to a rather common expectation, does not play an important role in the formation of the oscillations. Instead, the most important contributions come from a broad region of the 2D BZ distant from the center of the BZ. Combining symmetry arguments and direct calculations we show that orbital moments of the electronic states possess nonzero transverse components orthogonal to the direction of the spin magnetization. The account for this feature is crucial in the point-by-point analysis of the OMA. On the basis of the calculations for noncollinear spin configurations we suggest interpretations of two interesting experimental findings: fast temperature decay of the oscillation amplitude in MAE (N ) and unexpectedly strong spin mixing of the initial states of the photoemission process.

  7. On the Site-Decomposition of Magnetocrystalline Anisotropy Energy Using Ome-Electron Eigenstates

    Energy Technology Data Exchange (ETDEWEB)

    Aberg, Daniel [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Sadigh, Babak [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Benedict, Lorin X. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2015-10-26

    We discuss two di erent schemes for decomposing the magnetocrystalline anisotropy energy into atomic site-speci c contributions, and show that one of these, which uses projected single-particle states, is inherently ill-de ned in practical applications. We therefore argue that the other decomposition scheme, involving ground state matrix elements of the spin-orbit operator, is preferable for the numerical prediction of one-site contributions to the anisotropy.

  8. High-resolution EPR and the origin of the spectrum anisotropy of CH3 radicals in Ar, Kr, and CO matrices at liquid helium temperatures

    International Nuclear Information System (INIS)

    High-resolution EPR spectra of CH3 radicals have been observed in Ar, Kr, and CO matrices in the temperature range 1.6-4.2 K. These spectra showed an anisotropy of both the A-tensor and the g-tensor. It is shown that the experimental spectrum can be simulated as a spectrum of a powder sample with axially symmetric g and A tensors. Comparing the spectra in various matrices and studying samples of both pure matrices and mixture matrices, we found a significant contribution of the radical-matrix interaction to the anisotropy. The contribution of the radical rotation at helium temperatures to the CH3 spectrum appearance and the role it plays in the spectrum averaging are also discussed

  9. Energy spectrum of buoyancy-driven turbulence

    KAUST Repository

    Kumar, Abhishek

    2014-08-25

    Using high-resolution direct numerical simulation and arguments based on the kinetic energy flux Πu, we demonstrate that, for stably stratified flows, the kinetic energy spectrum Eu(k)∼k-11/5, the potential energy spectrum Eθ(k)∼k-7/5, and Πu(k)∼k-4/5 are consistent with the Bolgiano-Obukhov scaling. This scaling arises due to the conversion of kinetic energy to the potential energy by buoyancy. For weaker buoyancy, this conversion is weak, hence Eu(k) follows Kolmogorov\\'s spectrum with a constant energy flux. For Rayleigh-Bénard convection, we show that the energy supply rate by buoyancy is positive, which leads to an increasing Πu(k) with k, thus ruling out Bolgiano-Obukhov scaling for the convective turbulence. Our numerical results show that convective turbulence for unit Prandt number exhibits a constant Πu(k) and Eu(k)∼k-5/3 for a narrow band of wave numbers. © 2014 American Physical Society.

  10. Anisotropy and Strong-Coupling Effects on the Collective Mode Spectrum of Chiral Superconductors: Application to Sr2RuO4

    Directory of Open Access Journals (Sweden)

    James Avery Sauls

    2015-06-01

    Full Text Available Recent theories of Sr2RuO4 based on the interplay of strong interactions, spin-orbit coupling and multi-band anisotropy predict chiral or helical ground states with strong anisotropy of the pairing states, with deep minima in the excitation gap, as well as strong phase anisotropy for the chiral ground state. We develop time-dependent mean field theory to calculate the Bosonic spectrum for the class of 2D chiral superconductors spanning 3He-A to chiral superconductors with strong anisotropy. Chiral superconductors support a pair of massive Bosonic excitations of the time-reversed pairs labeled by their parity under charge conjugation. These modes are degenerate for 2D 3He-A. Crystal field anisotropy lifts the degeneracy. Strong anisotropy also leads to low-lying Fermions, and thus to channels for the decay of the Bosonic modes. Selection rules and phase space considerations lead to large asymmetries in the lifetimes and hybridization of the Bosonic modes with the continuum of un-bound Fermion pairs. We also highlight results for the excitation of the Bosonic modes by microwave radiation that provide clear signatures of the Bosonic modes of an anisotropic chiral ground state.

  11. Phase field model for strong anisotropy of kinetic and highly anisotropic interfacial energy

    Institute of Scientific and Technical Information of China (English)

    ZHANG Guo-wei; HOU Hua; CHENG Jun

    2006-01-01

    A phase-field model was established for simulating pure materials, which was calculated effectively and taken into account the strong anisotropy of kinetic and highly anisotropic interfacial energy. The anisotropy (strong kinetic and highly interfacial energy) of various degrees was simulated with numerical calculation. During a variety of interfacial anisotropy coefficient, equilibrium crystal shape varies from smoothness to corner. There has a critical value during the course of the transformation. When the anisotropy coefficenct is lower than the critical value, the growth velocity v increases monotonically with the increase of it. Whereas the anisotropy coefficent is higher than the critical value, the growth velocity decreases with the increases of it. During a variety of degree of supercooling, the growth velocity is under control from thermal diffusion to kinetics. Under the control of thermal diffusion, the growth velocity increases with the increase of degree of supercooling and tip radius R decreases with the increase of temperature. Under the control of kinetics, with the increase of degree of supercooling both V and R, which can not fit the traditional microcosmic theory.

  12. MAGNETIC FIELDS AND COSMIC-RAY ANISOTROPIES AT TeV ENERGIES

    Energy Technology Data Exchange (ETDEWEB)

    Battaner, Eduardo; Castellano, Joaquín; Masip, Manuel, E-mail: battaner@ugr.es, E-mail: jcastellano@correo.ugr.es, E-mail: masip@ugr.es [Departamento de Física Teórica y del Cosmos, Universidad de Granada, E-18071 Granada (Spain)

    2015-02-01

    Several cosmic-ray (CR) observatories have provided high-accuracy maps of the sky at TeV-PeV energies. The data reveal an O(0.1%) deficit from north galactic directions that peaks at 10 TeV and then evolves with the energy, together with other anisotropies at smaller angular scales. Using the Boltzmann equation, we derive expressions for the CR flux that fit these features. The anisotropies depend on the local interstellar magnetic field B{sub IS}, on the average galactic field B{sub R} in our vicinity, and on correlations between fluctuating quantities. We show that the initial dipole anisotropy along B{sub IS} can be modulated by changes in the global CR flow, and that a variation in the dipole direction would imply a given radius of coherence for the local B{sub IS}. We also show that small- and medium-scale anisotropies may appear when the full-sky anisotropy finds a field configuration acting as a magnetic lens.

  13. RKKY-like contributions to the magnetic anisotropy energy: 3 d adatoms on Pt(111) surface

    Science.gov (United States)

    Bouhassoune, Mohammmed; Dias, Manuel dos Santos; Zimmermann, Bernd; Dederichs, Peter H.; Lounis, Samir

    2016-09-01

    The magnetic anisotropy energy defines the energy barrier that stabilizes a magnetic moment. Utilizing density-functional-theory-based simulations and analytical formulations, we establish that this barrier is strongly modified by long-range contributions very similar to Friedel oscillations and Rudermann-Kittel-Kasuya-Yosida interactions. Thus, oscillations are expected and observed, with different decaying factors and highly anisotropic in realistic materials, which can switch nontrivially the sign of the magnetic anisotropy energy. This behavior is general, and for illustration we address the transition-metal adatoms, Cr, Mn, Fe, and Co deposited on a Pt(111) surface. We explain, in particular, the mechanisms leading to the strong site dependence of the magnetic anisotropy energy observed for Fe adatoms on a Pt(111) surface as revealed previously via first-principles-based simulations and inelastic scanning tunneling spectroscopy [A. A. Khajetoorians et al., Phys. Rev. Lett. 111, 157204 (2013), 10.1103/PhysRevLett.111.157204]. The same mechanisms are probably active for the site dependence of the magnetic anisotropy energy obtained for Fe adatoms on Pd or Rh(111) surfaces and for Co adatoms on a Rh(111) surface [P. Blonski et al., Phys. Rev. B 81, 104426 (2010), 10.1103/PhysRevB.81.104426].

  14. Structural invariance and the energy spectrum

    Energy Technology Data Exchange (ETDEWEB)

    Leyvraz, F.; Mendez, R.A.; Seligman, T.H. [Laboratorio de Cuernavaca, Instituto de Fisica, Unam (Italy)

    1999-10-01

    We extend the application of the concept of structural invariance to bounded time-independent systems. This concept, previously introduced by two of us to argue that the connection between random matrix theory and quantum systems with a chaotic classical counterpart is in fact largely exact in the semiclassical limit is extended to the energy spectra of bounded time-independent systems. We proceed by showing that the results obtained previously for the quasi-energies and eigenphases of the S-matrix can be extended to the eigenphases of the quantum Poincare map which is unitary in the semiclassical limit. We then show that its eigenphases in the chaotic case move rather stiffly around the unit circle and thus their local statistical fluctuations transfer to the energy spectrum via Bogomolny's prescription. We verify our results by studying numerically the properties of the eigenphases of the quantum Poincare map for billiards by using the boundary integral method. (author)

  15. Structural Invariance and the Energy Spectrum

    CERN Document Server

    Leyvraz, F; Seligman, T H

    1999-01-01

    We extend the application of the concept of structural invariance to bounded time independent systems. This concept, previously introduced by two of us to argue that the connection between random matrix theory and quantum systems with a chaotic classical counterpart is in fact largely exact in the semiclassical limit, is extended to the energy spectra of bounded time independent systems. We proceed by showing that the results obtained previously for the quasi-energies and eigenphases of the S-matrix can be extended to the eigenphases of the quantum Poincare map which is unitary in the semiclassical limit. We then show that its eigenphases in the chaotic case move rather stiffly around the unit circle and thus their local statistical fluctuations transfer to the energy spectrum via Bogomolny's prescription. We verify our results by studying numerically the properties of the eigenphases of the quantum Poincare map for billiards by using the boundary integral method.

  16. End of the cosmic neutrino energy spectrum

    Energy Technology Data Exchange (ETDEWEB)

    Anchordoqui, L.A. [Department of Physics and Astronomy, Lehman College, City University of New York, Bronx, NY 10468 (United States); Department of Physics, University of Wisconsin–Milwaukee, Milwaukee, WI 53201 (United States); Barger, V. [Department of Physics, University of Wisconsin, Madison, WI 53706 (United States); Goldberg, H. [Department of Physics, Northeastern University, Boston, MA 02115 (United States); Learned, J.G.; Marfatia, D.; Pakvasa, S. [Department of Physics and Astronomy, University of Hawaii at Manoa, Honolulu, HI 96822 (United States); Paul, T.C. [Department of Physics, University of Wisconsin–Milwaukee, Milwaukee, WI 53201 (United States); Department of Physics, Northeastern University, Boston, MA 02115 (United States); Weiler, T.J., E-mail: t.weiler@vanderbilt.edu [Department of Physics and Astronomy, Vanderbilt University, Nashville, TN 37235 (United States)

    2014-12-12

    There may be a high-energy cutoff of neutrino events in IceCube data. In particular, IceCube does not observe either continuum events above 2 PeV, or the Standard Model Glashow-resonance events expected at 6.3 PeV. There are also no higher energy neutrino signatures in the ANITA and Auger experiments. This absence of high-energy neutrino events motivates a fundamental restriction on neutrino energies above a few PeV. We postulate a simple scenario to terminate the neutrino spectrum that is Lorentz-invariance violating, but with a limiting neutrino velocity that is always smaller than the speed of light. If the limiting velocity of the neutrino applies also to its associated charged lepton, then a significant consequence is that the two-body decay modes of the charged pion are forbidden above two times the maximum neutrino energy, while the radiative decay modes are suppressed at higher energies. Such stabilized pions may serve as cosmic ray primaries.

  17. ADAPTIVE FULL-SPECTRUM SOLOR ENERGY SYSTEMS

    Energy Technology Data Exchange (ETDEWEB)

    Byard D. Wood

    2004-04-01

    This RD&D project is a three year team effort to develop a hybrid solar lighting (HSL) system that transports solar light from a paraboloidal dish concentrator to a luminaire via a large core polymer fiber optic. The luminaire can be a device to distribute sunlight into a space for the production of algae or it can be a device that is a combination of solar lighting and electric lighting. A benchmark prototype system has been developed to evaluate the HSL system. Sunlight is collected using a one-meter paraboloidal concentrator dish with two-axis tracking. A secondary mirror consisting of eight planar-segmented mirrors directs the visible part of the spectrum to eight fibers (receiver) and subsequently to eight luminaires. This results in about 8,200 lumens incident at each fiber tip. Each fiber can illuminate about 16.7 m{sup 2} (180 ft{sup 2}) of office space. The IR spectrum is directed to a thermophotovoltaic (TPV) array to produce electricity. During this reporting period, the project team made advancements in the design of the second generation (Alpha) system. For the Alpha system, the eight individual 12 mm fibers have been replaced with a centralized bundle of 3 mm fibers. The TRNSYS Full-Spectrum Solar Energy System model has been updated and new components have been added. The TPV array and nonimaging device have been tested and progress has been made in the fiber transmission models. A test plan was developed for both the high-lumen tests and the study to determine the non-energy benefits of daylighting. The photobioreactor team also made major advancements in the testing of model scale and bench top lab-scale systems.

  18. The energy spectrum of cosmic rays at the highest energies

    Directory of Open Access Journals (Sweden)

    Tsunesada Yoshiki

    2013-06-01

    Full Text Available One of several working groups established for this workshop was charged with examining results and methods associated with the UHECR energy spectrum. We summarize the results of our discussions, which include a better understanding of the analysis choices made by groups and their motivation. We find that the energy spectra determined by the larger experiments are consistent in normalization and shape after energy scaling factors are applied. Those scaling factors are within systematic uncertainties in the energy scale, and we discuss future work aimed at reducing these systematics.

  19. Limits on light-speed anisotropies from Compton scattering of high-energy electrons.

    Science.gov (United States)

    Bocquet, J-P; Moricciani, D; Bellini, V; Beretta, M; Casano, L; D'Angelo, A; Di Salvo, R; Fantini, A; Franco, D; Gervino, G; Ghio, F; Giardina, G; Girolami, B; Giusa, A; Gurzadyan, V G; Kashin, A; Knyazyan, S; Lapik, A; Lehnert, R; Levi Sandri, P; Lleres, A; Mammoliti, F; Mandaglio, G; Manganaro, M; Margarian, A; Mehrabyan, S; Messi, R; Nedorezov, V; Perrin, C; Randieri, C; Rebreyend, D; Rudnev, N; Russo, G; Schaerf, C; Sperduto, M L; Sutera, M C; Turinge, A; Vegna, V

    2010-06-18

    The possibility of anisotropies in the speed of light relative to the limiting speed of electrons is considered. The absence of sidereal variations in the energy of Compton-edge photons at the European Synchrotron Radiation Facility's GRAAL facility constrains such anisotropies representing the first nonthreshold collision-kinematics study of Lorentz violation. When interpreted within the minimal standard-model extension, this result yields the two-sided limit of 1.6×10(-14) at 95% confidence level on a combination of the parity-violating photon and electron coefficients (κ(o+))(YZ), (κ(o+))(ZX), c(TX), and c(TY). This new constraint provides an improvement over previous bounds by 1 order of magnitude.

  20. Sky-maps of the sidereal anisotropy of galactic cosmic ray intensity and its energy dependence

    CERN Document Server

    Munakata, K; Yasue, S; Kato, C; Mori, S; Takita, M; Duldig, M L; Humble, J E; Kota, J

    2008-01-01

    We analyze the sidereal daily variations observed between 1985 and 2006 at Matsushiro, Japan (MAT) and between 1993 and 2005 at Liapootah, Tasmania (LPT). These stations comprise the two hemisphere network (THN) of underground muon detectors in Japan and Australia. Yearly mean harmonic vectors at MAT and LPT are more or less stable without any significant change in phase and amplitude in correlation with either the solar activity- or magnetic-cycles. In this paper, therefore, we analyze the average anisotropy over the entire observation periods, i.e. 1985-2006 for MAT and 1993-2005 for LPT. We apply to the THN data a best-fitting analysis based on a model anisotropy in space identical to that adopted by Amenomori et al. (2007) for Tibet III data. The median energies of primary cosmic rays recorded are ~0.5 TeV for THN and ~5 TeV for the Tibet III experiment. It is shown that the intensity distribution of the best-fit anisotropy is quite similar to that derived from Tibet III data, regardless of the order of m...

  1. Cosmological anisotropy from non-comoving dark matter and dark energy

    CERN Document Server

    Harko, Tiberiu

    2013-01-01

    We consider a cosmological model in which the two major fluid components of the Universe, dark energy and dark matter, flow with distinct four-velocities. This cosmological configuration is equivalent to a single anisotropic fluid, expanding with a four-velocity that is an appropriate combination of the two fluid four-velocities. The energy density of the single cosmological fluid is larger than the sum of the energy densities of the two perfect fluids, i.e., dark energy and dark matter, respectively, and contains a correction term due to the anisotropy generated by the differences in the four-velocities. Furthermore, the gravitational field equations of the two-fluid anisotropic cosmological model are obtained for a Bianchi type I geometry. By assuming that the non-comoving motion of the dark energy and dark matter induces small perturbations in the homogeneous and isotropic Friedmann-Lemaitre-Robertson-Walker type cosmological background, and that the anisotropy parameter is small, the equations of the cosm...

  2. More light on the 2ν{sub 5} Raman overtone of SF{sub 6}: Can a weak anisotropic spectrum be due to a strong transition anisotropy?

    Energy Technology Data Exchange (ETDEWEB)

    Kremer, D.; Rachet, F.; Chrysos, M., E-mail: michel.chrysos@univ-angers.fr [LUNAM Université, Université d’Angers, CNRS UMR 6200, Laboratoire MOLTECH-Anjou, 2 Bd Lavoisier, 49045 Angers (France)

    2014-01-21

    Long known as a fully polarized band with a near vanishing depolarization ratio [η{sub s} = 0.05, W. Holzer and R. Ouillon, Chem. Phys. Lett. 24, 589 (1974)], the 2ν{sub 5} Raman overtone of SF{sub 6} has so far been considered as of having a prohibitively weak anisotropic spectrum [D. P. Shelton and L. Ulivi, J. Chem. Phys. 89, 149 (1988)]. Here, we report the first anisotropic spectrum of this overtone, at room temperature and for 13 gas densities ranging between 2 and 27 amagat. This spectrum is 10 times broader and 50 times weaker than the isotropic counterpart of the overtone [D. Kremer, F. Rachet, and M. Chrysos, J. Chem. Phys. 138, 174308 (2013)] and its profile much more sensitive to pressure effects than the profile of the isotropic spectrum. From our measurements an accurate value for the anisotropy matrix-element |〈000020|Δα|000000〉| was derived and this value was found to be comparable to that of the mean-polarizability ((000020), α{sup ¯} (000000)). Among other conclusions our study offers compelling evidence that, in Raman spectroscopy, highly polarized bands or tiny depolarization ratios are not necessarily incompatible with large polarizability anisotropy transition matrix-elements. Our findings and the way to analyze them suggest that new strategies should be developed on the basis of the complementarity inherent in independent incoherent Raman experiments that run with two different incident-beam polarizations, and on concerted efforts to ab initio calculate accurate data for first and second polarizability derivatives. Values for these derivatives are still rarities in the literature of SF{sub 6}.

  3. Search for light-speed anisotropies using Compton scattering of high-energy electrons

    CERN Document Server

    Rebreyend, Dominique

    2010-01-01

    Based on the high sensitivity of Compton scattering off ultra relativistic electrons, the possibility of anisotropies in the speed of light is investigated. The result discussed in this contribution is based on the gamma-ray beam of the ESRF's GRAAL facility (Grenoble, France) and the search for sidereal variations in the energy of the Compton-edge photons. The absence of oscillations yields the two-sided limit of 1.6 x 10^{-14} at 95 % confidence level on a combination of photon and electron coefficients of the minimal Standard Model Extension (mSME). This new constraint provides an improvement over previous bounds by one order of magnitude.

  4. Limits on light-speed anisotropies from Compton scattering of high-energy electrons

    CERN Document Server

    Bocquet, J -P; Bellini, V; Beretta, M; Casano, L; D'Angelo, A; Di Salvo, R; Fantini, A; Franco, D; Gervino, G; Ghio, F; Giardina, G; Girolami, B; Giusa, A; Gurzadyan, V G; Kashin, A; Knyazyan, S; Lapik, A; Lehnert, R; Sandri, P Levi; Lleres, A; Mammoliti, F; Mandaglio, G; Manganaro, M; Margarian, A; Mehrabyan, S; Messi, R; Nedorezov, V; Perrin, C; Randieri, C; Rebreyend, D; Rudnev, N; Russo, G; Schaerf, C; Sperduto, M L; Sutera, M C; Turinge, A; Vegna, V

    2010-01-01

    The possibility of anisotropies in the speed of light relative to the limiting speed of electrons is considered. The absence of sidereal variations in the energy of Compton-edge photons at the ESRF's GRAAL facility constrains such anisotropiesrepresenting the first non-threshold collision-kinematics study of Lorentz violation. When interpreted within the minimal Standard-Model Extension,this result yields the two-sided limit of 1.6 x 10^{-14} at 95 % confidence level on a combination of the parity-violating photon and electron coefficients

  5. Diffuse gamma radiation. [intensity, energy spectrum and spatial distribution from SAS 2 observations

    Science.gov (United States)

    Fichtel, C. E.; Simpson, G. A.; Thompson, D. J.

    1978-01-01

    Results are reported for an investigation of the intensity, energy spectrum, and spatial distribution of the diffuse gamma radiation detected by SAS 2 away from the galactic plane in the energy range above 35 MeV. The gamma-ray data are compared with relevant data obtained at other wavelengths, including 21-cm emission, radio continuum radiation, and the limited UV and radio information on local molecular hydrogen. It is found that there are two quite distinct components to the diffuse radiation, one of which shows a good correlation with the galactic matter distribution and continuum radiation, while the other has a much steeper energy spectrum and appears to be isotropic at least on a coarse scale. The galactic component is interpreted in terms of its implications for both local and more distant regions of the Galaxy. The apparently isotropic radiation is discussed partly with regard to the constraints placed on possible models by the steep energy spectrum, the observed intensity, and an upper limit on the anisotropy.

  6. Anisotropy and chemical composition of ultra-high energy cosmic rays using arrival directions measured by the Pierre Auger Observatory

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2011-06-01

    The Pierre Auger Collaboration has reported evidence for anisotropy in the distribution of arrival directions of the cosmic rays with energies E > E{sub th} = 5.5 × 10{sup 19} eV. These show a correlation with the distribution of nearby extragalactic objects, including an apparent excess around the direction of Centaurus A. If the particles responsible for these excesses at E > E{sub th} are heavy nuclei with charge Z, the proton component of the sources should lead to excesses in the same regions at energies E/Z. We here report the lack of anisotropies in these directions at energies above E{sub th}/Z (for illustrative values of Z = 6,13,26). If the anisotropies above E{sub th} are due to nuclei with charge Z, and under reasonable assumptions about the acceleration process, these observations imply stringent constraints on the allowed proton fraction at the lower energies.

  7. Anisotropy and chemical composition of ultra-high energy cosmic rays using arrival directions measured by the Pierre Auger Observatory

    CERN Document Server

    Abreu, P; Ahn, E J; Albuquerque, I F M; Allard, D; Allekotte, I; Allen, J; Allison, P; Castillo, J Alvarez; Alvarez-Muñiz, J; Ambrosio, M; Aminaei, A; Anchordoqui, L; Andringa, S; Antičić, T; Anzalone, A; Aramo, C; Arganda, E; Arqueros, F; Asorey, H; Assis, P; Aublin, J; Ave, M; Avenier, M; Avila, G; Bäcker, T; Balzer, M; Barber, K B; Barbosa, A F; Bardenet, R; Barroso, S L C; Baughman, B; Bäuml, J; Beatty, J J; Becker, B R; Becker, K H; Bellétoile, A; Bellido, J A; BenZvi, S; Berat, C; Bertou, X; Biermann, P L; Billoir, P; Blanco, F; Blanco, M; Bleve, C; Blümer, H; Boháčová, M; Boncioli, D; Bonifazi, C; Bonino, R; Borodai, N; Brack, J; Brogueira, P; Brown, W C; Bruijn, R; Buchholz, P; Bueno, A; Burton, R E; Caballero-Mora, K S; Caramete, L; Caruso, R; Castellina, A; Catalano, O; Cataldi, G; Cazon, L; Cester, R; Chauvin, J; Cheng, S H; Chiavassa, A; Chinellato, J A; Chou, A; Chudoba, J; Clay, R W; Coluccia, M R; Conceição, R; Contreras, F; Cook, H; Cooper, M J; Coppens, J; Cordier, A; Cotti, U; Coutu, S; Covault, C E; Creusot, A; Criss, A; Cronin, J; Curutiu, A; Dagoret-Campagne, S; Dallier, R; Dasso, S; Daumiller, K; Dawson, B R; de Almeida, R M; De Domenico, M; De Donato, C; de Jong, S J; De La Vega, G; Junior, W J M de Mello; Neto, J R T de Mello; De Mitri, I; de Souza, V; de Vries, K D; Decerprit, G; del Peral, L; Deligny, O; Dembinski, H; Dhital, N; Di Giulio, C; Diaz, J C; Castro, M L Díaz; Diep, P N; Dobrigkeit, C; Docters, W; D'Olivo, J C; Dong, P N; Dorofeev, A; Anjos, J C dos; Dova, M T; D'Urso, D; Dutan, I; Ebr, J; Engel, R; Erdmann, M; Escobar, C O; Etchegoyen, A; Luis, P Facal San; Tapia, I Fajardo; Falcke, H; Farrar, G; Fauth, A C; Fazzini, N; Ferguson, A P; Ferrero, A; Fick, B; Filevich, A; Filipčič, A; Fliescher, S; Fracchiolla, C E; Fraenkel, E D; Fröhlich, U; Fuchs, B; Gaior, R; Gamarra, R F; Gambetta, S; García, B; Gámez, D García; Garcia-Pinto, D; Gascon, A; Gemmeke, H; Gesterling, K; Ghia, P L; Giaccari, U; Giller, M; Glass, H; Gold, M S; Golup, G; Albarracin, F Gomez; Berisso, M Gómez; Gonçalves, P; Gonzalez, D; Gonzalez, J G; Gookin, B; Góra, D; Gorgi, A; Gouffon, P; Gozzini, S R; Grashorn, E; Grebe, S; Griffith, N; Grigat, M; Grillo, A F; Guardincerri, Y; Guarino, F; Guedes, G P; Guzman, A; Hague, J D; Hansen, P; Harari, D; Harmsma, S; Harton, J L; Haungs, A; Hebbeker, T; Heck, D; Herve, A E; Hojvat, C; Hollon, N; Holmes, V C; Homola, P; Hörandel, J R; Horneffer, A; Hrabovský, M; Huege, T; Insolia, A; Ionita, F; Italiano, A; Jarne, C; Jiraskova, S; Kadija, K; Kampert, K H; Karhan, P; Kasper, P; Kégl, B; Keilhauer, B; Keivani, A; Kelley, J L; Kemp, E; Kieckhafer, R M; Klages, H O; Kleifges, M; Kleinfeller, J; Knapp, J; Koang, D -H; Kotera, K; Krohm, N; Krömer, O; Kruppke-Hansen, D; Kuehn, F; Kuempel, D; Kulbartz, J K; Kunka, N; La Rosa, G; Lachaud, C; Lautridou, P; Leão, M S A B; Lebrun, D; Lebrun, P; de Oliveira, M A Leigui; Lemiere, A; Letessier-Selvon, A; Lhenry-Yvon, I; López, K Link R; Agüera, A Lopez; Louedec, K; Bahilo, J Lozano; Lucero, A; Ludwig, M; Lyberis, H; Maccarone, M C; Macolino, C; Maldera, S; Mandat, D; Mantsch, P; Mariazzi, A G; Marin, J; Marin, V; Maris, I C; Falcon, H R Marquez; Marsella, G; Martello, D; Martin, L; Martinez, H; Bravo, O Martínez; Mathes, H J; Matthews, J; Matthews, J A J; Matthiae, G; Maurizio, D; Mazur, P O; Medina-Tanco, G; Melissas, M; Melo, D; Menichetti, E; Menshikov, A; Mertsch, P; Meurer, C; Mićanović, S; Micheletti, M I; Miller, W; Miramonti, L; Mollerach, S; Monasor, M; Ragaigne, D Monnier; Montanet, F; Morales, B; Morello, C; Moreno, E; Moreno, J C; Morris, C; Mostafá, M; Moura, C A; Mueller, S; Muller, M A; Müller, G; Münchmeyer, M; Mussa, R; Navarra, G; Navarro, J L; Navas, S; Necesal, P; Nellen, L; Nelles, A; Nhung, P T; Niemietz, L; Nierstenhoefer, N; Nitz, D; Nosek, D; Nožka, L; Nyklicek, M; Oehlschläger, J; Olinto, A; Oliva, P; Olmos-Gilbaja, V M; Ortiz, M; Pacheco, N; Selmi-Dei, D Pakk; Palatka, M; Pallotta, J; Palmieri, N; Parente, G; Parizot, E; Parra, A; Parsons, R D; Pastor, S; Paul, T; Pech, M; Pȩkala, J; Pelayo, R; Pepe, I M; Perrone, L; Pesce, R; Petermann, E; Petrera, S; Petrinca, P; Petrolini, A; Petrov, Y; Petrovic, J; Pfendner, C; Phan, N; Piegaia, R; Pierog, T; Pieroni, P; Pimenta, M; Pirronello, V; Platino, M; Ponce, V H; Pontz, M; Privitera, P; Prouza, M; Quel, E J; Querchfeld, S; Rautenberg, J; Ravel, O; Ravignani, D; Revenu, B; Ridky, J; Riggi, S; Risse, M; Ristori, P; Rivera, H; Rizi, V; Roberts, J; Robledo, C; de Carvalho, W Rodrigues; Rodriguez, G; Martino, J Rodriguez; Rojo, J Rodriguez; Rodriguez-Cabo, I; Rodríguez-Frías, M D; Ros, G; Rosado, J; Rossler, T; Roth, M; Rouillé-d'Orfeuil, B; Roulet, E; Rovero, A C; Rühle, C; Salamida, F; Salazar, H; Salina, G; Sánchez, F; Santander, M; Santo, C E; Santos, E; Santos, E M; Sarazin, F; Sarkar, B; Sarkar, S; Sato, R; Scharf, N; Scherini, V; Schieler, H; Schiffer, P; Schmidt, A; Schmidt, F; Schmidt, T; Scholten, O; Schoorlemmer, H; Schovancova, J; Schovánek, P; Schröder, F; Schulte, S; Schuster, D; Sciutto, S J; Scuderi, M; Segreto, A; Settimo, M; Shadkam, A; Shellard, R C; Sidelnik, I; Sigl, G; Lopez, H H Silva; Śmiałkowski, A; Šmída, R; Snow, G R; Sommers, P; Sorokin, J; Spinka, H; Squartini, R; Stapleton, J; Stasielak, J; Stephan, M; Strazzeri, E; Stutz, A; Suarez, F; Suomijärvi, T; Supanitsky, A D; Šuša, T; Sutherland, M S; Swain, J; Szadkowski, Z; Szuba, M; Tamashiro, A; Tapia, A; Tartare, M; Taşcău, O; Ruiz, C G Tavera; Tcaciuc, R; Tegolo, D; Thao, N T; Thomas, D; Tiffenberg, J; Timmermans, C; Tiwari, D K; Tkaczyk, W; Peixoto, C J Todero; Tomé, B; Tonachini, A; Travnicek, P; Tridapalli, D B; Tristram, G; Trovato, E; Tueros, M; Ulrich, R; Unger, M; Urban, M; Galicia, J F Valdés; Valiño, I; Valore, L; Berg, A M van den; Varela, E; Cárdenas, B Vargas; Vázquez, J R; Vázquez, R A; Veberič, D; Verzi, V; Vicha, J; Videla, M; Villaseñor, L; Wahlberg, H; Wahrlich, P; Wainberg, O; Warner, D; Watson, A A; Weber, M; Weidenhaupt, K; Weindl, A; Westerhoff, S; Whelan, B J; Wieczorek, G; Wiencke, L; Wilczyńska, B; Wilczyński, H; Will, M; Williams, C; Winchen, T; Winders, L; Winnick, M G; Wommer, M; Wundheiler, B; Yamamoto, T; Yapici, T; Younk, P; Yuan, G; Yushkov, A; Zamorano, B; Zas, E; Zavrtanik, D; Zavrtanik, M; Zaw, I; Zepeda, A; Ziolkowski, M

    2011-01-01

    The Pierre Auger Collaboration has reported evidence for anisotropy in the distribution of arrival directions of the cosmic rays with energies $E>E_{th}=5.5\\times 10^{19}$ eV. These show a correlation with the distribution of nearby extragalactic objects, including an apparent excess around the direction of Centaurus A. If the particles responsible for these excesses at $E>E_{th}$ are heavy nuclei with charge $Z$, the proton component of the sources should lead to excesses in the same regions at energies $E/Z$. We here report the lack of anisotropies in these directions at energies above $E_{th}/Z$ (for illustrative values of $Z=6,\\ 13,\\ 26$). If the anisotropies above $E_{th}$ are due to nuclei with charge $Z$, and under reasonable assumptions about the acceleration process, these observations imply stringent constraints on the allowed proton fraction at the lower energies.

  8. Energy spectrum of stably-stratified and convective turbulent flows

    Science.gov (United States)

    Verma, Mahendra; Kumar, Abhishek

    2015-11-01

    In the inertial range of fluid turbulence, the energy flux is constant, while the energy spectrum scales as k - 5 / 3 (k=wavenumber). The buoyancy however could change the phenomenology dramatically. Bolgiano and Obukhov (1959) had conjectured that stably stratified flows (as in atmosphere) exhibits a decrease in the energy flux as k - 4 / 5 due to the conversion of kinetic energy to the potential energy, consequently, the energy spectrum scales as k - 11 / 5. We show using detailed numerical analysis that the stably stratified flows indeed exhibit k - 11 / 5 energy spectrum for Froude numbers Fr near unity. The flow becomes anisotropic for small Froude numbers. For weaker buoyancy (large Fr), the kinetic energy follows Kolmogorov's spectrum with a constant energy flux. However, in convective turbulence, the energy flux is a nondecreasing function of wavenumber since the buoyancy feeds positively into the kinetic energy. Hence, the kinetic energy spectrum is Kolmogorov-like (k - 5 / 3) or shallower. We also demonstrate the above scaling using a shell model of buoyancy-driven turbulence.

  9. Measurement of energy dependence of fission fragment angular anisotropy for resonance neutron induced fission of 235U aligned target

    International Nuclear Information System (INIS)

    The results of the experiment on measuring the energy dependence of fission fragment angular anisotropy in resonance neutron induced fission of 235U aligned target in energy region up to 42 eV are presented. The agreement with the data of Pattenden and Postma in resonances is good enough, while the theoretical curve, calculated using the R-matrix multilevel two fission channel approach, does not seem to describe the energy dependence of fission fragment angular anisotropy property. The necessity of taking into account the interference between levels with different spins is discussed. 11 refs., 2 figs

  10. Statistical Significance of Small Scale Anisotropy in Arrival Directions of Ultra-High Energy Cosmic Rays

    CERN Document Server

    Yoshiguchi, H; Sato, K; Yoshiguchi, Hiroyuki; Nagataki, Shigehiro; Sato, Katsuhiko

    2004-01-01

    Recently, the High Resolution Fly's Eye (HiRes) experiment claims that there is no small scale anisotropy in the arrival distribution of ultra-high energy cosmic rays (UHECRs) above $E>10^{19}$ eV contrary to the Akeno Giant Air Shower Array (AGASA) observation. In this paper, we discuss the statistical significance of this discrepancy between the two experiments. We calculate arrival distribution of UHECRs above $10^{19}$ eV predicted by the source models constructed using the Optical Redshift Survey galaxy sample. We apply the new method developed by us for calculating arrival distribution in the presence of the galactic magnetic field. The great advantage of this method is that it enables us to calculate UHECR arrival distribution with lower energy ($\\sim 10^{19}$ eV) than previous studies within reasonable time by following only the trajectories of UHECRs actually reaching the earth. It has been realized that the small scale anisotropy observed by the AGASA can be explained with the source number density ...

  11. Empirical determination of charm quark energy loss and its consequences for azimuthal anisotropy

    CERN Document Server

    Younus, Mohammed

    2012-01-01

    We propose an empirical model to determine the form of energy loss of charm quarks due to multiple scatterings in quark gluon plasma by demanding a good description of production of D mesons and non-photonic electrons in relativistic collision of heavy nuclei at RHIC and LHC energies. Best results are obtained when we approximate the momentum loss per collision $\\Delta p_T \\propto \\alpha \\, p_T$, where $\\alpha$ is a constant depending on the centrality and the centre of mass energy. Comparing our results with those obtained earlier for drag coefficients estimated using Langevin equation for heavy quarks we find that up to half of the energy loss of charm quarks at top RHIC energy could be due to collisions while that at LHC energy at 2760 GeV/A the collisional energy loss could be about one third of the total. Estimates are obtained for azimuthal anisotropy in momentum spectra of heavy mesons, due to this energy loss. We further suggest that energy loss of charm quarks may lead to an enhanced production of D-...

  12. Numerical Studies of Electromagnetic Instabilities in Intense Charged Particle Beams with Large Energy Anisotropy

    CERN Document Server

    Startsev, Edward; Lee, Wei-li

    2005-01-01

    In intense charged particle beams with large energy anisotropy, free energy is available to drive transverse electromagnetic Weibel-type instabilities. Such slow-wave transverse electromagnetic instabilities can be described by the so-called Darwin model, which neglects the fast-wave portion of the displacement current. The Weibel instability may also lead to an increase in the longitudinal velocity spread, which would make the focusing of the beam difficult and impose a limit on the minimum spot size achievable in heavy ion fusion experiments. This paper reports the results of recent numerical studies of the Weibel instability using the Beam Eigenmode And Spectra (bEASt) code for space-charge-dominated, low-emittance beams with large tune depression. To study the nonlinear stage of the instability, the Darwin model is being developed and incorporated into the Beam Equilibrium Stability and Transport(BEST) code.

  13. The first moment of azimuthal anisotropy in nuclear collisions from AGS to LHC energies

    CERN Document Server

    Singha, Subhash; Keane, Declan

    2016-01-01

    We review topics related to the first moment of azimuthal anisotropy ($v_1$), commonly known as directed flow, focusing on both charged particles and identified particles from heavy-ion collisions. Beam energies from the highest available, at the CERN LHC, down to projectile kinetic energies per nucleon of a few GeV per nucleon, as studied in experiments at the Brookhaven AGS, fall within our scope. We focus on experimental measurements and on theoretical work where direct comparisons with experiment have been emphasized. The physics addressed or potentially addressed by this review topic includes the study of Quark Gluon Plasma, and more generally, investigation of the Quantum Chromodynamics phase diagram and the equation of state describing the accessible phases.

  14. EFFECTS OF THE TEMPERATURE ANISOTROPY ON THE MASER INSTABILITY EXCITED BY LOWER ENERGY CUTOFF BEHAVIOR

    International Nuclear Information System (INIS)

    The electron-cyclotron maser (ECM) conventionally driven by velocity anisotropies of energetic electrons trapped in magnetic fields is one of the most important radio-emission mechanisms in astrophysics. Recently, Wu and Tang proposed that a proper lower energy cutoff behavior of power-law electrons can effectively excite the ECM emission. This paper considers effects of temperature anisotropy on this new ECM mechanism. The results show that the growth rates of the ECM emissions increase with βperpendicular0 and β||0, where βperpendicular0 and β||0 are the perpendicular and parallel velocity spreads (in units of the light velocity c) of the energetic electron beam, respectively. Moreover, the growth rates of O1 and X2 modes both sensitively depend on the ratio of the electron-cyclotron frequency to the plasma frequency Ω and reach their extremum values at Ω ≅ 1.5 for the O1 mode and at Ω ≅ 1.0 for the X2 mode. Meanwhile, as the mean velocity of the electron beam βs (in units of c) increases, the growth rate of the O1 mode remains approximately constant and that of the X2 mode decreases considerably.

  15. The Cosmic Rays Energy Spectrum observed by the TALE detector

    Science.gov (United States)

    Abuzayyad, Tareq; Telescope Array Collaboration Collaboration

    2016-03-01

    We report on a cosmic ray energy spectrum measurement by the Telescope Array Low-Energy extension (TALE) fluorescence detector (FD). The TALE FD is an air fluorescence detector which is also sensitive to the Cerenkov light produced by shower particles. Low energy cosmic rays, in the PeV energy range, are detectable by TALE as ``Cerenkov Events''. Using these events, we measure the energy spectrum from a low energy of 4 PeV to an energy greater than 100 PeV. Starting at around 100 PeV, TALE also observes showers by their fluorescence light; and above this energy fluorescence becomes the dominant light production mechanism by which most showers are observed. The event processing and reconstruction procedures are identical for both low and high energy regions. This allows for treating the Cherenkov events and Fluorescence events as a single data set and thus calculating a single cosmic rays energy spectrum based on this data set, which extends from an energy of 4 PeV to above 1 EeV. In this talk, we will describe the detector, explain the technique, and present results from the measurement of the spectrum in this energy range by the Telescope Array experiment.

  16. Energy detection for spectrum sensing in cognitive radio

    CERN Document Server

    Atapattu, Saman; Jiang, Hai

    2014-01-01

    This Springer Brief focuses on the current state-of-the-art research on spectrum sensing by using energy detection, a low-complexity and low-cost technique. It includes a comprehensive summary of recent research, fundamental theories, possible architectures, useful performance measurements of energy detection and applications of energy detection. Concise, practical chapters explore conventional energy detectors, alternative forms of energy detectors, performance measurements, diversity techniques and cooperative networks. The careful analysis enables reader to identify the most efficient techn

  17. Energy Spectrum of Ground State and Excitation Spectrum of Quasi-particle for Hard-Core Boson in Optical Lattices

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    We investigate the energy spectrum of ground state and quasi-particle excitation spectrum of hard-core bosons, which behave very much like spinless noninteracting fermions, in optical lattices by means of the perturbation expansion and Bogoliubov approach. The results show that the energy spectrum has a single band structure, and the energy is lower near zero momentum; the excitation spectrum gives corresponding energy gap, and the system is in Mott-insulating state at Tonks limit. The analytic result of energy spectrum is in good agreement with that calculated in terms of Green's function at strong correlation limit.

  18. The High Energy Spectrum of NGC 4151

    CERN Document Server

    Beckmann, V; Gehrels, N; Soldi, S; Lubinski, P; Zdziarski, A A; Petrucci, P O; Malzac, J

    2005-01-01

    We present the first INTEGRAL observations of the type 1.5 Seyfert galaxy NGC 4151. Combining several INTEGRAL observations performed during 2003, totaling about 400 ks of exposure time, allows us to study the spectrum in the 2 - 300 keV range. The measurements presented here reveal an overall spectrum from X-rays up to soft gamma-rays that can be described by an absorbed (NH = 6.9e22 1/cm**2) model based on a Compton continuum from a hot electron population (kT = 94 keV) from an optically thick (tau = 1.3) corona, reflected on cold material (R=0.7), consistent with earlier claims. The time resolved analysis shows little variation of the spectral parameters over the duration of the INTEGRAL observations. The comparison with CGRO/OSSE data shows that the same spectral model can be applied over a time span of 15 years, with flux variations of the order of a factor of 2 and changes in the underlying continuum reflected by the temperature of the electron population (kT = 50 - 100 keV). When modeled with an expone...

  19. Anisotropy studies around the Galactic Centre at EeV energies with the Auger Observatory

    Energy Technology Data Exchange (ETDEWEB)

    Aglietta, M.; Aguirre, C.; Allard, D.; Allekotte, I.; Allison, P.; Alvarez, C.; Alvarez-Muniz, J.; Ambrosio, M.; Anchordoqui, L.; Anjos, J.C.; Aramo, C.; /Centro Atomico Bariloche /Buenos Aires, IAFE /Buenos Aires, CONICET /Pierre Auger Observ. /La Plata U. /Natl. Tech. U., San Rafael /Adelaide U. /Catholic U. of Bolivia, La Paz /Bolivia U. /Rio de Janeiro, CBPF /Sao Paulo U.

    2006-07-01

    Data from the Pierre Auger Observatory are analyzed to search for anisotropies near the direction of the Galactic Centre at EeV energies. The exposure of the surface array in this part of the sky is already significantly larger than that of the fore-runner experiments. Our results do not support previous findings of localized excesses in the AGASA and SUGAR data. We set an upper bound on a point-like flux of cosmic rays arriving from the Galactic Centre which excludes several scenarios predicting sources of EeV neutrons from Sagittarius A. Also the events detected simultaneously by the surface and fluorescence detectors (the ''hybrid'' data set), which have better pointing accuracy but are less numerous than those of the surface array alone, do not show any significant localized excess from this direction.

  20. Anisotropy studies around the galactic centre at EeV energies with the Auger Observatory

    CERN Document Server

    Abraham, J; Aguirre, C; Allard, D; Allekotte, I; Allison, P; Alvarez, C; Alvarez-Muñiz, J; Ambrosio, M; Anchordoqui, Luis A; Anjos, J C; Aramo, C; Arisaka, K; Armengaud, E; Arneodo, F; Arqueros, F; Asch, T; Asorey, H; Atulugama, B S; Aublin, J; Ave, M; Avila, G; Bacelar, J; Backer, T; Badagnani, D O; Barbosa-Ademarlaudo, F; Barbosa, H M J; Barkhausen, M; Barnhill, D; Barroso, S L C; Bauleo, P; Beatty, J; Beau, T; Becker, B R; Becker, K H; Bellido, J A; Ben Zvi, S; Bérat, C; Bergmann, T; Bernardini, P; Bertou, X; Biermann, P L; Billoir, P; Blanch-Bigas, O; Blanco, F; Blasi, P; Bleve, C; Blümer, H; Boghrat, P; Bohacova, M; Bonifazi, C; Bonino, R; Boratav, M; Brack, J; Brunet, J M; Buchholz, P; Busca, N G; Caballero-Mora, K S; Cai, B; Camin, D V; Capdevielle, J N; Caruso, R; Castellina, A; Cataldi, G; Cazon, L; Cester, R; Chauvin, J; Chiavassa, A; Chinellato, J A; Chou, A; Chye, J; Claes, D; Clark, P D J; Clay, R W; Clay, S B; Connolly, B; Cordier, A; Cotti, U; Coutu, S; Covault, C E; Cronin, J; Dagoret-Campagne, S; Dang Quang, T; Darriulat, Pierre; Daumiller, K; Dawson, B R; De Almeida, R M; De Carvalho, L A; De Donato, C; De Jong, S J; De Mello Junior, W J M; De Mello-Neto, J R T; De Mitri, I; De Oliveira, M A L; De Souza, V; Del Peral, L; Deligny, O; Della Selva, A; Delle Fratte, C; Dembinski, H; Di Giulio, C; Diaz, J C; Dobrigkeit, C; D'Olivo, J C; Dornic, D; Dorofeev, A; Dova, M T; D'Urso, D; Duvernois, M A; Engel, R; Epele, L N; Erdmann, M; Escobar, C O; Etchegoyen, A; Ewers, A; Facal San Luis, P; Falcke, H; Fauth, A C; Fazio, D; Fazzini, N; Fernández, A; Ferrer, F; Ferry, S; Fick, B; Filevich, A; Filipcic, A; Fleck, I; Fokitis, E; Fonte, R; Fuhrmann, D; Fulgione, W; García, B; Garcia-Pinto, D; Garrard, L; Garrido, X; Geenen, H; Gelmini, G; Gemmeke, H; Geranios, A; Ghia, P L; Giller, M; Gitto, J; Glass, H; Gobbi, F; Gold, M S; Gomez Albarracin, F; Gomez Berisso, M; Gómez-Herrero, R; Goncalvesdo Amaral, M; Gongora, J P; González, D; Gonzalez, J G; González, M; Gora, D; Gorgi, A; Gouffon, P; Grassi, V; Grillo, A; Grunfeld, C; Grupen, C; Guarino, F; Guedes, G P; Gutíerrez, J; Hague, J D; Hamilton, J C; Harakeh, M N; Harari, D; Harmsma, S; Hartmann, S; Harton, J L; Haungs, A; Healy, M D; Hebbeker, T; Heck, D; Hojvat, C; Homola, P; Horandel, J; Horneffer, A; Horvat, M; Hrabovsky, M; Huege, T; Iarlori, M; Insolia, A; Kaducak, M; Kalashev, O; Kampert, K H; Keilhauer, B; Kemp, E; Klages, H O; Kleifges, M; Kleinfeller, J; Knapik, R; Knapp, J; Koang, D H; Kolotaev, Yu; Kopmann, A; Krömer, O; Kuhlman, S; Kuijpers, J; Kunka, N; Kusenko, A; Lachaud, C; Lago, B L; Lebrun, D; Lebrun, P; Lee, J; Letessier-Selvon, A A; Leuthold, M; Lhenry-Yvon, I; Longo, G; López, R; López-Aguera, A; Lucero, A; Maldera, S; Malek, M; Maltezos, S; Mancarella, G; Mancenido, M E; Mandat, D; Mantsch, P; Mariazzi, A G; Maris, I C; Martello, D; Martínez, N; Martínez, J; Martínez, O; Mathes, H J; Matthews, J; Matthews, J A J; Matthiae, Giorgio; Maurin, G; Maurizio, D; Mazur, P O; McCauley, T; McEwen, M; McNeil, R R; Medina, G; Medina, M C; Medina Tanco, G; Meli, A; Melo, D; Menichetti, E; Menshikov, A; Meurer, C; Meyhandan, R; Micheletti, M I; Miele, G; Miller, W; Mollerach, S; Monasor, M; Monnier Ragaigne, D; Montanet, François; Morales, B; Morello, C; Moreno, E; Morris, C; Mostafa, M; Muller, M A; Mussa, R; Navarra, G; Nellen, L; Newman-Holmes, C; Newton, D; Nguyen Thi, T; Nichol, R; Nierstenhofer, N; Nitz, D; Nogima, H; Nosek, D; Nozka, L; Oehlschläger, J; Ohnuki, T; Olinto, A; Oliveira, L F A; Olmos-Gilbaja, V M; Ortiz, M; Ostapchenko, S; Otero, L; Palatka, M; Pallotta, J; Parente, G; Parizot, E; Parlati, S; Patel, M; Paul, T; Payet, K; Pech, M; Pekala, J; Pelayo, R; Pepe, I M; Perrone, L; Petrera, S; Petrinca, P; Petrov, Y; Pham Ngoc, D; Pham Thi, T N; Piegaia, R; Pierog, T; Pisanti, O; Porter, T A; Pouryamout, J; Prado Junior, L; Privitera, P; Prouza, M; Quel, E J; Rautenberg, J; Reis, H C; Reucroft, S; Revenu, B; Rídky, J; Risi, A; Risse, M; Rivière, C; Rizi, V; Robbins, S; Roberts, M; Robledo, C; Rodríguez, G; Rodriguez Frias, D; Rodríguez-Martino, J; Rodriguez Rojo, J; Ros, G; Rosado, J; Roth, M; Roucelle, C; Rouille-d'Orfeuil, B; Roulet, E; Rovero, A C; Salamida, F; Salazar, H; Salina, G; Sánchez, F; Santander, M; Santos, E M; Sarkar, S; Sato, R; Scherini, V; Schieler, H; Schmidt, T; Scholten, O; Schovanek, P; Schussler, F; Sciutto, S J; Scuderi, M; Semikoz, Dmitry V; Sequeiros, G; Shellard, R C; Siffert, B B; Sigl, G; Skelton, P; Slater, W; Smetniansky De Grande, N; Smialkowski, A; Smida, R; Smith, B E; Snow, G R; Sokolsky, P; Sommers, P; Sorokin, J; Spinka, H; Strazzeri, E; Stutz, A; Suárez, F; Suomijärvi, T; Supanitsky, A D; Swain, J; Szadkowski, Z; Tamashiro, A; Tamburro, A; Tascau, O; Ticona, R; Timmermans, C; Tkaczyk, W; Todero Peixoto, C J; Tonachini, A; Torresi, D; Travnicek, P; Tripathi, A; Tristram, G; Tscherniakhovski, D; Tueros, M; Tunnicliffe, V; Ulrich, R; Unger, M; Urban, M; Valdés-Galicia, J F; Valino, I; Valore, L; Vanden Berg, A M; Van Elewyck, V; Vázquez, R A; Veberic, D; Veiga, A; Velarde, A; Venters, T; Verzi, V; Videla, M; Villaseñor, L; Vo Van, T; Vorobiov, S; Voyvodic, L; Wahlberg, H; Wainberg, O; Waldenmaier, T; Walker, P; Warner, D; Watson, A A; Westerhoff, S; Wiebusch, C; Wieczorek, G J; Wiencke, L; Wilczynska, B; Wilczynski, H; Wileman, C; Winnick, M G; Xu, J; Yamamoto, T; Younk, P; Zas, E; Zavrtanik, D; Zavrtanik, M; Zech, A; Zepeda, A; Zha, M; Ziolkowski, M

    2006-01-01

    Data from the Pierre Auger Observatory are analyzed to search for anisotropies near the direction of the Galactic Centre at EeV energies. The exposure of the surface array in this part of the sky is already significantly larger than that of the fore-runner experiments. Our results do not support previous findings of localized excesses in the AGASA and SUGAR data. We set an upper bound on a point-like flux of cosmic rays arriving from the Galactic Centre which excludes several scenarios predicting sources of EeV neutrons from Sagittarius $A$. Also the events detected simultaneously by the surface and fluorescence detectors (the `hybrid' data set), which have better pointing accuracy but are less numerous than those of the surface array alone, do not show any significant localized excess from this direction.

  1. Anisotropy studies around the galactic centre at EeV energies with the Auger Observatory

    Science.gov (United States)

    Abraham, J.; Aglietta, M.; Aguirre, C.; Allard, D.; Allekotte, I.; Allison, P.; Alvarez, C.; Alvarez-Muñiz, J.; Ambrosio, M.; Anchordoqui, L.; Anjos, J. C.; Aramo, C.; Arisaka, K.; Armengaud, E.; Arneodo, F.; Arqueros, F.; Asch, T.; Asorey, H.; Atulugama, B. S.; Aublin, J.; Ave, M.; Avila, G.; Bacelar, J.; Bäcker, T.; Badagnani, D.; Barbosa, A. F.; Barbosa, H. M. J.; Barkhausen, M.; Barnhill, D.; Barroso, S. L. C.; Bauleo, P.; Beatty, J.; Beau, T.; Becker, B. R.; Becker, K. H.; Bellido, J. A.; Benzvi, S.; Berat, C.; Bergmann, T.; Bernardini, P.; Bertou, X.; Biermann, P. L.; Billoir, P.; Blanch-Bigas, O.; Blanco, F.; Blasi, P.; Bleve, C.; Blümer, H.; Boghrat, P.; Boháčová, M.; Bonifazi, C.; Bonino, R.; Boratav, M.; Brack, J.; Brunet, J. M.; Buchholz, P.; Busca, N. G.; Caballero-Mora, K. S.; Cai, B.; Camin, D. V.; Capdevielle, J. N.; Caruso, R.; Castellina, A.; Cataldi, G.; Cazón, L.; Cester, R.; Chauvin, J.; Chiavassa, A.; Chinellato, J. A.; Chou, A.; Chye, J.; Claes, D.; Clark, P. D. J.; Clay, R. W.; Clay, S. B.; Connolly, B.; Cordier, A.; Cotti, U.; Coutu, S.; Covault, C. E.; Cronin, J.; Dagoret-Campagne, S.; Quang, T. Dang; Darriulat, P.; Daumiller, K.; Dawson, B. R.; de Almeida, R. M.; de Carvalho, L. A.; de Donato, C.; de Jong, S. J.; de Mello, W. J. M.; de Mello Neto, J. R. T.; de Mitri, I.; de Oliveira, M. A. L.; de Souza, V.; Del Peral, L.; Deligny, O.; Della Selva, A.; Delle Fratte, C.; Dembinski, H.; di Giulio, C.; Diaz, J. C.; Dobrigkeit, C.; D'Olivo, J. C.; Dornic, D.; Dorofeev, A.; Dova, M. T.; D'Urso, D.; Duvernois, M. A.; Engel, R.; Epele, L.; Erdmann, M.; Escobar, C. O.; Etchegoyen, A.; Ewers, A.; Facal San Luis, P.; Falcke, H.; Fauth, A. C.; Fazio, D.; Fazzini, N.; Fernández, A.; Ferrer, F.; Ferry, S.; Fick, B.; Filevich, A.; Filipčič, A.; Fleck, I.; Fokitis, E.; Fonte, R.; Fuhrmann, D.; Fulgione, W.; García, B.; Garcia-Pinto, D.; Garrard, L.; Garrido, X.; Geenen, H.; Gelmini, G.; Gemmeke, H.; Geranios, A.; Ghia, P. L.; Giller, M.; Gitto, J.; Glass, H.; Gobbi, F.; Gold, M. S.; Gomez Albarracin, F.; Gómez Berisso, M.; Gómez Herrero, R.; Gonçalves Do Amaral, M.; Gongora, J. P.; Gonzalez, D.; Gonzalez, J. G.; González, M.; Góra, D.; Gorgi, A.; Gouffon, P.; Grassi, V.; Grillo, A.; Grunfeld, C.; Grupen, C.; Guarino, F.; Guedes, G. P.; Gutiérrez, J.; Hague, J. D.; Hamilton, J. C.; Harakeh, M. N.; Harari, D.; Harmsma, S.; Hartmann, S.; Harton, J. L.; Haungs, A.; Healy, M. D.; Hebbeker, T.; Heck, D.; Hojvat, C.; Homola, P.; Hörandel, J.; Horneffer, A.; Horvat, M.; Hrabovský, M.; Huege, T.; Iarlori, M.; Insolia, A.; Kaducak, M.; Kalashev, O.; Kampert, K. H.; Keilhauer, B.; Kemp, E.; Klages, H. O.; Kleifges, M.; Kleinfeller, J.; Knapik, R.; Knapp, J.; Koang, D.-H.; Kolotaev, Y.; Kopmann, A.; Krömer, O.; Kuhlman, S.; Kuijpers, J.; Kunka, N.; Kusenko, A.; Lachaud, C.; Lago, B. L.; Lebrun, D.; Lebrun, P.; Lee, J.; Letessier-Selvon, A.; Leuthold, M.; Lhenry-Yvon, I.; Longo, G.; López, R.; Lopez Agüera, A.; Lucero, A.; Maldera, S.; Malek, M.; Maltezos, S.; Mancarella, G.; Manceñido, M. E.; Mandat, D.; Mantsch, P.; Mariazzi, A. G.; Maris, I. C.; Martello, D.; Martinez, N.; Martínez, J.; Martínez, O.; Mathes, H. J.; Matthews, J.; Matthews, J. A. J.; Matthiae, G.; Maurin, G.; Maurizio, D.; Mazur, P. O.; McCauley, T.; McEwen, M.; McNeil, R. R.; Medina, G.; Medina, M. C.; Medina Tanco, G.; Meli, A.; Melo, D.; Menichetti, E.; Menshikov, A.; Meurer, Chr.; Meyhandan, R.; Micheletti, M. I.; Miele, G.; Miller, W.; Mollerach, S.; Monasor, M.; Monnier Ragaigne, D.; Montanet, F.; Morales, B.; Morello, C.; Moreno, E.; Morris, C.; Mostafá, M.; Muller, M. A.; Mussa, R.; Navarra, G.; Nellen, L.; Newman-Holmes, C.; Newton, D.; Thi, T. Nguyen; Nichol, R.; Nierstenhöfer, N.; Nitz, D.; Nogima, H.; Nosek, D.; Nožka, L.; Oehlschläger, J.; Ohnuki, T.; Olinto, A.; Oliveira, L. F. A.; Olmos-Gilbaja, V. M.; Ortiz, M.; Ostapchenko, S.; Otero, L.; Palatka, M.; Pallotta, J.; Parente, G.; Parizot, E.; Parlati, S.; Patel, M.; Paul, T.; Payet, K.; Pech, M.; PeĶala, J.; Pelayo, R.; Pepe, I. M.; Perrone, L.; Petrera, S.; Petrinca, P.; Petrov, Y.; Pham Ngoc, D.; Pham Thi, T. N.; Piegaia, R.; Pierog, T.; Pisanti, O.; Porter, T. A.; Pouryamout, J.; Prado, L.; Privitera, P.; Prouza, M.; Quel, E. J.; Rautenberg, J.; Reis, H. C.; Reucroft, S.; Revenu, B.; Řídký, J.; Risi, A.; Risse, M.; Rivière, C.; Rizi, V.; Robbins, S.; Roberts, M.; Robledo, C.; Rodriguez, G.; Rodríguez Frías, D.; Rodriguez Martino, J.; Rodriguez Rojo, J.; Ros, G.; Rosado, J.; Roth, M.; Roucelle, C.; Rouillé-D'Orfeuil, B.; Roulet, E.; Rovero, A. C.; Salamida, F.; Salazar, H.; Salina, G.; Sánchez, F.; Santander, M.; Santos, E. M.; Sarkar, S.; Sato, R.; Scherini, V.; Schieler, H.; Schmidt, T.; Scholten, O.; Schovánek, P.; Schüssler, F.; Sciutto, S. J.; Scuderi, M.; Semikoz, D.; Sequeiros, G.; Shellard, R. C.; Siffert, B. B.; Sigl, G.; Skelton, P.; Slater, W.; de Grande, N. Smetniansky; Smiałkowski, A.; Šmída, R.; Smith, B. E.; Snow, G. R.; Sokolsky, P.; Sommers, P.; Sorokin, J.; Spinka, H.; Strazzeri, E.; Stutz, A.; Suarez, F.; Suomijärvi, T.; Supanitsky, A. D.; Swain, J.; Szadkowski, Z.; Tamashiro, A.; Tamburro, A.; Tascau, O.; Ticona, R.; Timmermans, C.; Tkaczyk, W.; Todero Peixoto, C. J.; Tonachini, A.; Torresi, D.; Travnicek, P.; Tripathi, A.; Tristram, G.; Tscherniakhovski, D.; Tueros, M.; Tunnicliffe, V.; Ulrich, R.; Unger, M.; Urban, M.; Valdés Galicia, J. F.; Valiño, I.; Valore, L.; van den Berg, A. M.; van Elewyck, V.; Vazquez, R. A.; Veberič, D.; Veiga, A.; Velarde, A.; Venters, T.; Verzi, V.; Videla, M.; Villaseñor, L.; Vo van, T.; Vorobiov, S.; Voyvodic, L.; Wahlberg, H.; Wainberg, O.; Waldenmaier, T.; Walker, P.; Warner, D.; Watson, A. A.; Westerhoff, S.; Wiebusch, C.; Wieczorek, G.; Wiencke, L.; Wilczyńska, B.; Wilczyński, H.; Wileman, C.; Winnick, M. G.; Xu, J.; Yamamoto, T.; Younk, P.; Zas, E.; Zavrtanik, D.; Zavrtanik, M.; Zech, A.; Zepeda, A.; Zha, M.; Ziolkowski, M.; Pierre Auger Collaboration

    2007-04-01

    Data from the Pierre Auger Observatory are analyzed to search for anisotropies near the direction of the Galactic Centre at EeV energies. The exposure of the surface array in this part of the sky is already significantly larger than that of the fore-runner experiments. Our results do not support previous findings of localized excesses in the AGASA and SUGAR data. We set an upper bound on a point-like flux of cosmic rays arriving from the Galactic Centre which excludes several scenarios predicting sources of EeV neutrons from Sagittarius A. Also the events detected simultaneously by the surface and fluorescence detectors (the ‘hybrid’ data set), which have better pointing accuracy but are less numerous than those of the surface array alone, do not show any significant localized excess from this direction.

  2. Teager Energy Spectrum for Fault Diagnosis of Rolling Element Bearings

    Science.gov (United States)

    Feng, Zhipeng; Wang, Tianjin; Zuo, Ming J.; Chu, Fulei; Yan, Shaoze

    2011-07-01

    Localized damage of rolling element bearings generates periodic impulses during running. The repeating frequency of impulses is a key indicator for diagnosing the localized damage of bearings. A new method, called Teager energy spectrum, is proposed to diagnose the faults of rolling element bearings. It exploits the unique advantages of Teager energy operator in detecting transient components in signals to extract periodic impulses of bearing faults, and uses the Fourier spectrum of Teager energy to identify the characteristic frequency of bearing faults. The effectiveness of the proposed method is validated by analyzing the experimental bearing vibration signals.

  3. Anisotropy and chemical composition of ultra-high energy cosmic rays using arrival directions measured by the Pierre Auger Observatory

    NARCIS (Netherlands)

    Abreu, P.; Aglietta, M.; Ahn, E. J.; Albuquerque, J. F. M.; Allard, D.; Allekotte, I.; Allen, J.; Allison, P.; Alvarez Castilo, J.; Alvarez-Muniz, J.; Ambrosio, M.; Aminaei, A.; Anchordoqui, L.; Andringa, S.; Anticic, T.; Anzalone, A.; Aramo, C.; Arganda, E.; Arqueros, F.; Asorey, H.; Assis, P.; Aublin, J.; Ave, M.; Avenier, Ni.; Avila, G.; Baecker, T.; Balzer, M.; Barber, K. B.; Barbosa, A. F.; Bardenet, R.; Barroso, S. L. C.; Baughman, B.; Baeuml, J.; Beatty, J. J.; Becker, B. R.; Becker, K. H.; Belletoile, A.; Bellido, J. A.; BenZvi, S.; Berat, C.; Bertou, X.; Biermann, P. L.; Billoir, P.; Blanco, F.; Blanco, M.; Bleve, C.; Bluemer, H.; Bohacova, M.; Boncioli, D.; Bonifazi, C.; Bonino, R.; Borodai, N.; Brack, J.; Brogueira, P.; Brown, W. C.; Bruijn, R.; Buchholz, P.; Bueno, A.; Burton, R. E.; Caballero-Mora, K. S.; Caramete, L.; Caruso, R.; Castellina, A.; Catalano, O.; Cataldi, G.; Cazon, L.; Cester, R.; Chauvin, J.; Cheng, S. H.; Chiavassa, A.; Chinellato, J. A.; Chou, A.; Chudoba, J.; Clay, R. W.; Coluccia, M. R.; Conceicao, R.; Contreras, F.; Cook, H.; Cooper, M. J.; Coppens, J.; Cordier, A.; Cotti, U.; Coutu, S.; Covault, C. E.; Creusot, A.; Criss, A.; Cronin, J.; Curutiu, A.; Dagoret-Campagne, S.; Dallier, R.; Dasso, S.; Daumiller, K.; Dawson, B. R.; de Almeida, R. M.; De Domenico, M.; De Donato, C.; de Jong, S. J.; De La Vega, G.; de Mello Junior, W. J. M.; de Mello Neto, J. R. T.; De Mitri, I.; de Souza, V.; de Vries, K. D.; Decerprit, G.; del Peral, L.; Deligny, O.; Dembinski, H.; Dhital, N.; Di Giulio, C.; Diaz, J. C.; Diaz Castro, M. L.; Diep, P. N.; Dobrigkeit, C.; Docters, W.; D'Olivo, J. C.; Dong, P. N.; Dorofeev, A.; dos Anjos, J. C.; Dova, M. T.; D'Urso, D.; Dutan, I.; Ebr, J.; Engel, R.; Erdmann, M.; Escobar, C. O.; Etchegoyen, A.; Luis, P. Facal San; Tapia, I. Fajardo; Falcke, H.; Farrar, G.; Fauth, A. C.; Fazzini, N.; Ferguson, A. P.; Ferrero, A.; Fick, B.; Filevich, A.; Filipcic, A.; Fliescher, S.; Fracchiolla, C. E.; Fraenkel, E. D.; Froehlich, U.; Fuchs, B.; Gaior, R.; Gamarra, R. F.; Gambetta, S.; Garcia, B.; Garcia Gamez, D.; Garcia-Pinto, D.; Gascon, A.; Gemmeke, H.; Gesterling, K.; Ghia, P. L.; Giaccari, U.; Giller, M.; Glass, H.; Gold, M. S.; Golup, G.; Gomez Albarracin, F.; Gomez Berisso, M.; Goncalves, P.; Gonzalez, D.; Gonzalez, J. G.; Gookin, B.; Gora, D.; Gorgi, A.; Gouffon, P.; Gozzini, S. R.; Grashorn, E.; Grebe, S.; Griffith, N.; Grigat, M.; Grillo, A. F.; Guardincerri, Y.; Guarino, F.; Guedes, G. P.; Guzman, A.; Hague, J. D.; Hansen, P.; Harari, D.; Harmsma, S.; Harton, J. L.; Haungs, A.; Hebbeker, T.; Heck, D.; Herve, A. E.; Hojvat, C.; Hollon, N.; Holmes, V. C.; Homola, P.; Hoerandel, J. R.; Horneffer, A.; Hrabovsky, M.; Huege, T.; Insolia, A.; Ionita, F.; Italiano, A.; Jarne, C.; Jiraskova, S.; Kadija, K.; Kampert, K. H.; Karhan, P.; Kasper, P.; Kegl, B.; Keilhauer, B.; Keivani, A.; Kelley, J. L.; Kemp, E.; Kieckhafer, R. M.; Klages, H. O.; Kleifges, M.; Kleinfeller, J.; Knapp, J.; Koang, D. -H.; Kotera, K.; Krohm, N.; Kroemer, O.; Kruppke-Hansen, D.; Kuehn, F.; Kuempel, D.; Kulbartz, J. K.; Kunka, N.; La Rosa, G.; Lachaud, C.; Lautridou, P.; Leao, M. S. A. B.; Lebrun, D.; Lebrun, P.; Leigui de Oliveira, M. A.; Lemiere, A.; Letessier-Selvon, A.; Lhenry-Yvon, I.; Link, K.; Lopez, R.; Lopez Agueera, A.; Louedec, K.; Lozano Bahilo, J.; Lucero, A.; Ludwig, M.; Lyberis, H.; Maccarone, M. C.; Macolino, C.; Maldera, S.; Mandat, D.; Mantsch, P.; Mariazzi, A. G.; Marin, J.; Marin, V.; Maris, I. C.; Marquez Falcon, H. R.; Marsella, G.; Martello, D.; Martinez, H.; Martinez Bravo, O.; Mathes, H. J.; Matthews, J.; Matthews, J. A. J.; Matthiae, G.; Maurizio, D.; Mazur, P. O.; Medina-Tanco, G.; Melissas, M.; Melo, D.; Menichetti, E.; Menshikov, A.; Mertsch, P.; Meurer, C.; Micanovic, S.; Micheletti, M. I.; Miller, W.; Miramonti, L.; Mollerach, S.; Monasor, M.; Ragaigne, D. Monnier; Montanet, F.; Morales, B.; Morello, C.; Moreno, E.; Moreno, J. C.; Morris, C.; Mostafa, M.; Moura, C. A.; Mueller, S.; Muller, M. A.; Mueller, G.; Muenchmeyer, M.; Mussa, R.; Navarra, G.; Navarro, J. L.; Navas, S.; Necesal, P.; Nellen, L.; Nelles, A.; Nhung, P. T.; Niemietz, L.; Nierstenhoefer, N.; Nitz, D.; Nosek, D.; Nozka, L.; Nyklicek, M.; Oehlschlaeger, J.; Olinto, A.; Oliva, P.; Olmos-Gilbaja, V. M.; Ortiz, M.; Pacheco, N.; Selmi-Dei, D. Pakk; Palatka, M.; Pallotta, J.; Palmieri, N.; Parente, G.; Parizot, E.; Parra, A.; Parsons, R. D.; Pastor, S.; Paul, T.; Pech, M.; Pekala, J.; Pelayo, R.; Pepe, I. M.; Perrone, L.; Pesce, R.; Petermann, E.; Petrera, S.; Petrinca, P.; Petrolini, A.; Petrov, Y.; Petrovic, J.; Pfendner, C.; Phan, N.; Piegaia, R.; Pierog, T.; Pieroni, P.; Pimenta, M.; Pirronello, V.; Platino, M.; Ponce, V. H.; Pontz, M.; Privitera, P.; Prouza, M.; Quel, E. J.; Querchfeld, S.; Rautenberg, J.; Ravel, O.; Ravignani, D.; Revenu, B.; Ridky, J.; Riggi, S.; Risse, M.; Ristori, P.; Rivera, H.; Rizi, V.; Roberts, J.; Robledo, C.; Rodrigues de Carvalho, W.; Rodriguez, G.; Rodriguez Martino, J.; Rodriguez Rojo, J.; Rodriguez-Cabo, I.; Rodriguez-Frias, M. D.; Ros, G.; Rosado, J.; Rossler, T.; Roth, M.; Rouille-d'Orfeuil, B.; Roulet, E.; Rovero, A. C.; Ruehle, C.; Salamida, F.; Salazar, H.; Salina, G.; Sanchez, F.; Santander, M.; Santo, C. E.; Santos, E.; Santos, E. M.; Sarazin, F.; Sarkar, B.; Sarkar, S.; Sato, R.; Scharf, N.; Scherini, V.; Schieler, H.; Schiffer, P.; Schmidt, A.; Schmidt, F.; Schmidt, T.; Scholten, O.; Schoorlemmer, H.; Schovancova, J.; Schovanek, P.; Schroeder, F.; Schulte, S.; Schuster, D.; Sciutto, S. J.; Scuderi, M.; Segreto, A.; Settimo, M.; Shadkam, A.; Shellard, R. C.; Sidelnik, I.; Sigl, G.; Silva Lopez, H. H.; Smialkowski, A.; Smida, R.; Snow, G. R.; Sommers, P.; Sorokin, J.; Spinka, H.; Squartini, R.; Stapleton, J.; Stasielak, J.; Stephan, M.; Strazzeri, E.; Stutz, A.; Suarez, F.; Suomijaervi, T.; Supanitsky, A. D.; Susa, T.; Sutherland, M. S.; Swain, J.; Szadkowski, Z.; Szuba, M.; Tamashiro, A.; Tapia, A.; Tartare, M.; Tascau, O.; Ruiz, C. G. Tavera; Tcaciuc, R.; Tegolo, D.; Thao, N. T.; Thomas, D.; Tiffenberg, J.; Timmermans, C.; Tiwari, D. K.; Tkaczyk, W.; Todero Peixoto, C. J.; Tome, B.; Tonachini, A.; Travnicek, P.; Tridapalli, D. B.; Tristram, G.; Trovato, E.; Tueros, M.; Ulrich, R.; Unger, M.; Urban, M.; Valdes Galicia, J. F.; Valino, I.; Valore, L.; van den Berg, A. M.; Varela, E.; Vargas Cardenas, B.; Vazquez, J. R.; Vazquez, R. A.; Veberic, D.; Verzi, V.; Vicha, J.; Videla, M.; Villasenor, L.; Wahlberg, H.; Wahrlich, P.; Wainberg, O.; Warner, D.; Watson, A. A.; Weber, M.; Weidenhaupt, K.; Weindl, A.; Westerhoff, S.; Whelan, B. J.; Wieczorek, G.; Wiencke, L.; Wilczynska, B.; Wilczynski, H.; Will, M.; Williams, C.; Winchen, T.; Winders, L.; Winnick, M. G.; Wommer, M.; Wundheiler, B.; Yamamoto, T.; Yapici, T.; Younk, P.; Yuan, G.; Yushkov, A.; Zamorano, B.; Zas, E.; Zavrtanik, D.; Zavrtanik, M.; Zaw, I.; Zepeda, A.; Ziolkowski, M.; Martin, L.

    2011-01-01

    The Pierre Auger Collaboration has reported. evidence for anisotropy in the distribution of arrival directions of the cosmic rays with energies E > E(th) = 5.5 x 10(19) eV. These show a correlation with the distribution of nearby extragalactic objects, including an apparent excess around the directi

  4. NREL Spectrum of Clean Energy Innovation: Issue 3 (Book)

    Energy Technology Data Exchange (ETDEWEB)

    2012-11-01

    This quarterly magazine is dedicated to stepping beyond the technical journals to reveal NREL's vital work in a real-world context for our stakeholders. Continuum provides insights into the latest and most impactful clean energy innovations, while spotlighting those talented researchers and unique facilities that make it all happen. This edition focuses on the NREL Spectrum of Clean Energy Innovation.

  5. Hadron intensity and energy spectrum at 4380 m above level

    Science.gov (United States)

    Cananov, S. D.; Chadranyan, E. K.; Khizanishvili, L. A.; Ladaria, N. K.; Roinishvili, N. N.

    1985-01-01

    The flux value of hadrons with E (sup gamma) h or = 5 TeV, where E (sup gamma) h or = is the energy transferred into electromagnetic component is presented. It is shown that the energy spectrum slope beta of hadrons with E h or = 20 TeV is equal to 1.9.

  6. Strain control of magnetocrystalline anisotropy and energy product of MnGa alloys

    Energy Technology Data Exchange (ETDEWEB)

    Al-Aqtash, Nabil, E-mail: nalaqtash@unomaha.edu; Sabirianov, Renat

    2015-10-01

    We investigate the energy product of MnGa alloys as function of Mn concentration and applied elastic strain. Using the density functional theory (DFT) based method we calculated the magnetocrystalline anisotropy (MAE) and magnetization of Mn–Ga alloys as function of composition, e.g. Mn and Ga, and examined their variation under applied strain. Our calculations show that MAE is very large ~22–27 M erg/cm{sup 3} in all three considered compositions, e.g. MnGa, Mn{sub 3}Ga and Mn{sub 1.66}Ga. We show that MAE is very robust in MnGa system and remains large in wide range of concentrations and strains both compressive and tensile. We find that bi-axial tensile strain increases MAE in Mn{sub 1.66}Ga alloys. Our study shows that the variation of MAE as function of Mn content is related to the change in electronic structure and, specifically, the Fermi level position with electron population variation. We estimated the theoretical limit of the energy product (BH){sub max} of MnGa, Mn{sub 3}Ga and Mn{sub 1.66}Ga alloys as 23.65, 4.06 and 13.64 MGOe, respectively. We find that volume expansion of the MnGa alloys (by appropriate doping) should increase the magnetization and the energy product of these alloys.

  7. Search for Anisotropy of Ultra-High Energy Cosmic Rays with the Telescope Array Experiment

    CERN Document Server

    Abu-Zayyad, T; Allen, M; Anderson, R; Azuma, R; Barcikowski, E; Belz, J W; Bergman, D R; Blake, S A; Cady, R; Cheon, B G; Chiba, J; Chikawa, M; Cho, E J; Cho, W R; Fujii, H; Fujii, T; Fukuda, T; Fukushima, M; Hanlon, W; Hayashi, K; Hayashi, Y; Hayashida, N; Hibino, K; Hiyama, K; Honda, K; Iguchi, T; Ikeda, D; Ikuta, K; Inoue, N; Ishii, T; Ishimori, R; Ivanov, D; Iwamoto, S; Jui, C C H; Kadota, K; Kakimoto, F; Kalashev, O; Kanbe, T; Kasahara, K; Kawai, H; Kawakami, S; Kawana, S; Kido, E; Kim, H B; Kim, H K; Kim, J H; Kim, J H; Kitamoto, K; Kitamura, S; Kitamura, Y; Kobayashi, K; Kobayashi, Y; Kondo, Y; Kuramoto, K; Kuzmin, V; Kwon, Y J; Lim, S I; Machida, S; Martens, K; Martineau, J; Matsuda, T; Matsuura, T; Matsuyama, T; Matthews, J N; Minamino, M; Miyata, K; Murano, Y; Myers, I; Nagasawa, K; Nagataki, S; Nakamura, T; Nam, S W; Nonaka, T; Ogio, S; Ohnishi, M; Ohoka, H; Oki, K; Oku, D; Okuda, T; Oshima, A; Ozawa, S; Park, I H; Pshirkov, M S; Rodriguez, D C; Roh, S Y; Rubtsov, G; Ryu, D; Sagawa, H; Sakurai, N; Sampson, A L; Scott, L M; Shah, P D; Shibata, F; Shibata, T; Shimodaira, H; Shin, B K; Shin, J I; Shirahama, T; Smith, J D; Sokolsky, P; Sonley, T J; Springer, R W; Stokes, B T; Stratton, S R; Stroman, T; Suzuki, S; Takahashi, Y; Takeda, M; Taketa, A; Takita, M; Tameda, Y; Tanaka, H; Tanaka, K; Tanaka, M; Thomas, S B; Thomson, G B; Tinyakov, P; Tkachev, I; Tokuno, H; Tomida, T; Troitsky, S; Tsunesada, Y; Tsutsumi, K; Tsuyuguchi, Y; Uchihori, Y; Udo, S; Ukai, H; Vasiloff, G; Wada, Y; Wong, T; Wood, M; Yamakawa, Y; Yamane, R; Yamaoka, H; Yamazaki, K; Yang, J; Yoneda, Y; Yoshida, S; Yoshii, H; Zhou, X; Zollinger, R; Zundel, Z

    2012-01-01

    We study the anisotropy of Ultra-High Energy Cosmic Ray (UHECR) events collected by the Telescope Array (TA) detector in the first 40 months of operation. Following earlier studies, we examine event sets with energy thresholds of 10 EeV, 40 EeV, and 57 EeV. We find that the distributions of the events in right ascension and declination are compatible with an isotropic distribution in all three sets. We then compare with previously reported clustering of the UHECR events at small angular scales. No significant clustering is found in the TA data. We then check the events with E>57 EeV for correlations with nearby active galactic nuclei. No significant correlation is found. Finally, we examine all three sets for correlations with the large-scale structure of the Universe. We find that the two higher-energy sets are compatible with both an isotropic distribution and the hypothesis that UHECR sources follow the matter distribution of the Universe (the LSS hypothesis), while the event set with E>10 EeV is compatibl...

  8. Multislot Simultaneous Spectrum Sensing and Energy Harvesting in Cognitive Radio

    Directory of Open Access Journals (Sweden)

    Xin Liu

    2016-07-01

    Full Text Available In cognitive radio (CR, the spectrum sensing of the primary user (PU may consume some electrical power from the battery capacity of the secondary user (SU, resulting in a decrease in the transmission power of the SU. In this paper, a multislot simultaneous spectrum sensing and energy harvesting model is proposed, which uses the harvested radio frequency (RF energy of the PU signal to supply the spectrum sensing. In the proposed model, the sensing duration is divided into multiple sensing slots consisting of one local-sensing subslot and one energy-harvesting subslot. If the PU is detected to be present in the local-sensing subslot, the SU will harvest RF energy of the PU signal in the energy-harvesting slot, otherwise, the SU will continue spectrum sensing. The global decision on the presence of the PU is obtained through combining local sensing results from all the sensing slots by adopting “Or-logic Rule”. A joint optimization problem of sensing time and time splitter factor is proposed to maximize the throughput of the SU under the constraints of probabilities of false alarm and detection and energy harvesting. The simulation results have shown that the proposed model can clearly improve the maximal throughput of the SU compared to the traditional sensing-throughput tradeoff model.

  9. Effects of the Energy Error Distribution of Fluorescence Telescopes on the UHECR energy spectrum

    CERN Document Server

    Carvalho, Washington; de Souza, Vitor; 10.1016/j.astropartphys.2007.04.010

    2008-01-01

    The measurement of the ultra high energy cosmic ray (UHECR) spectrum is strongly affected by uncertainties on the reconstructed energy. The determination of the presence or absence of the GZK cutoff and its position in the energy spectrum depends not only on high statistics but also on the shape of the energy error distribution. Here we determine the energy error distribution for fluorescence telescopes, based on a Monte Carlo simulation. The HiRes and Auger fluorescence telescopes are simulated in detail. We analyze the UHECR spectrum convolved with this energy error distribution. We compare this spectrum with one convolved with a lognormal error distribution as well as with a Gaussian error distribution. We show that the energy error distribution for fluorescence detectors can not be represented by these known distributions. We conclude that the convolved energy spectrum will be smeared but not enough to affect the GZK cutoff detection. This conclusion stands for both HiRes and Auger fluorescence telescopes...

  10. Interference Energy Spectrum of the Infinite Square Well

    Directory of Open Access Journals (Sweden)

    Mordecai Waegell

    2016-04-01

    Full Text Available Certain superposition states of the 1-D infinite square well have transient zeros at locations other than the nodes of the eigenstates that comprise them. It is shown that if an infinite potential barrier is suddenly raised at some or all of these zeros, the well can be split into multiple adjacent infinite square wells without affecting the wavefunction. This effects a change of the energy eigenbasis of the state to a basis that does not commute with the original, and a subsequent measurement of the energy now reveals a completely different spectrum, which we call the interference energy spectrum of the state. This name is appropriate because the same splitting procedure applied at the stationary nodes of any eigenstate does not change the measurable energy of the state. Of particular interest, this procedure can result in measurable energies that are greater than the energy of the highest mode in the original superposition, raising questions about the conservation of energy akin to those that have been raised in the study of superoscillations. An analytic derivation is given for the interference spectrum of a given wavefunction Ψ ( x , t with N known zeros located at points s i = ( x i , t i . Numerical simulations were used to verify that a barrier can be rapidly raised at a zero of the wavefunction without significantly affecting it. The interpretation of this result with respect to the conservation of energy and the energy-time uncertainty relation is discussed, and the idea of alternate energy eigenbases is fleshed out. The question of whether or not a preferred discrete energy spectrum is an inherent feature of a particle’s quantum state is examined.

  11. Schwinger-boson approach to anisotropy ferrimagnetic chain with bond alternation

    Institute of Scientific and Technical Information of China (English)

    李殷翔; 陈斌

    2015-01-01

    We use the Schwinger-boson approach to study the anisotropy ferrimagnetic spin-(1/2,1) chain with bond alternation. Based on the effect of bond alternationδ, we obtain energy gap, free energy, and specific heat, respectively. The specific heat with larger bond alternation (δ >0.7) displays a peak at low temperature. Based on the effect of X X Z anisotropy parameter∆, we present excited spectrums, free energy, and specific heat, respectively.

  12. High Energy Atmospheric Neutrino Fluxes From a Realistic Primary Spectrum

    Science.gov (United States)

    Campos Penha, Felipe; Dembinski, Hans; Gaisser, Thomas K.; Tilav, Serap

    2016-03-01

    Atmospheric neutrino fluxes depend on the energy spectrum of primary nucleons entering the top of the atmosphere. Before the advent of AMANDA and the IceCube Neutrino Observatory, measurements of the neutrino fluxes were generally below ~ 1TeV , a regime in which a simple energy power law sufficed to describe the primary spectrum. Now, IceCube's muon neutrino data extends beyond 1PeV , including a combination of neutrinos from astrophysical sources with background from atmospheric neutrinos. At such high energies, the steepening at the knee of the primary spectrum must be accounted for. Here, we describe a semi-analytical approach for calculating the atmospheric differential neutrino fluxes at high energies. The input is a realistic primary spectrum consisting of 4 populations with distinct energy cutoffs, each with up to 7 representative nuclei, where the parameters were extracted from a global fit. We show the effect of each component on the atmospheric neutrino spectra, above 10TeV . The resulting features follow directly from recent air shower measurements included in the fit. Felipe Campos Penha gratefully acknowledges financial support from CAPES (Processo BEX 5348/14-5), CNPq (Processo 142180/2012-2), and the Bartol Research Institute.

  13. Modification of magnetic anisotropy in metallic glasses using high-energy ion beam irradiation

    Indian Academy of Sciences (India)

    K V Amrute; U R Mhatre; S K Sinha; D C Kothari; R Nagarajan; D Kanjilal

    2002-05-01

    Heavy ion irradiation in the electronic stopping power region induces macroscopic dimensional change in metallic glasses and introduces magnetic anisotropy in some magnetic materials. The present work is on the irradiation study of ferromagnetic metallic glasses, where both dimensional change and modification of magnetic anisotropy are expected. Magnetic anisotropy was measured using Mössbauer spectroscopy of virgin and irradiated Fe40Ni40B20 and Fe40Ni38Mo4B18 metallic glass ribbons. 90 MeV 127I beam was used for the irradiations. Irradiation doses were 5 × 1013 and 7.5 × 1013 ions/cm2. The relative intensity ratios 23 of the second and third lines of the Mössbauer spectra were measured to determine the magnetic anisotropy. The virgin samples of both the materials display in-plane magnetic anisotropy, i.e., the spins are oriented parallel to the ribbon plane. Irradiation is found to cause reduction in magnetic anisotropy. Near-complete randomization of magnetic moments is observed at high irradiation doses. Correlation is found between the residual stresses introduced by ion irradiation and the change in magnetic anisotropy.

  14. Energy and angular anisotropy optimisation of a p-type diode for in vivo dosimetry in photon-beam radiotherapy.

    Science.gov (United States)

    Greene, Simon; Price, Robert A

    2005-01-01

    We present simulation work using the Monte Carlo code MCNPX that shows that there is a possibility of improving the silicon p-type diode as a radiation dosemeter, by altering the construction of the diode. Altering the diode die thickness can reduce the inherent angular anisotropy of the diode, with little effect on its energy response. Conversely, the contact material and geometry have a large impact on the energy response with little effect on the inherent angular anisotropy. By correct choice of contact material, the typical over-response -100 keV relative to the response at 60Co energy can be reduced from approximately 20 to 4. It is expected that further enhancements may be made with different geometries and materials.

  15. Measurement of the magnetic anisotropy energy constants for magneto-optical recording media

    Science.gov (United States)

    Hajjar, R. A.; Wu, T. H.; Mansuripur, M.

    1992-01-01

    Measurement of the magneto-optical polar Kerr effect is performed on rare earth-transition metal (RE-TM) amorphous films using in-plane fields. From this measurement and the measurement of the saturation magnetization using a vibrating sample magnetometer (VSM), the magnetic anisotropy constants are determined. The temperature dependence is presented of the magnetic anisotropy in the range of -175 to 175 C. The results show a dip in the anisotropy near magnetic compensation. This anomaly is explained based on the finite exchange coupling between the rare earth and transition metal subnetworks.

  16. A search for anisotropy in the arrival directions of ultra high energy cosmic rays recorded at the Pierre Auger Observatory

    Energy Technology Data Exchange (ETDEWEB)

    Abreu, P.

    2012-01-01

    Observations of cosmic ray arrival directions made with the Pierre Auger Observatory have previously provided evidence of anisotropy at the 99% CL using the correlation of ultra high energy cosmic rays (UHECRs) with objects drawn from the Veron-Cetty Veron catalog. In this paper we report on the use of three catalog independent methods to search for anisotropy. The 2pt-L, 2pt+ and 3pt methods, each giving a different measure of self-clustering in arrival directions, were tested on mock cosmic ray data sets to study the impacts of sample size and magnetic smearing on their results, accounting for both angular and energy resolutions. If the sources of UHECRs follow the same large scale structure as ordinary galaxies in the local Universe and if UHECRs are deflected no more than a few degrees, a study of mock maps suggests that these three methods can efficiently respond to the resulting anisotropy with a P-value = 1.0% or smaller with data sets as few as 100 events. Using data taken from January 1, 2004 to July 31, 2010 we examined the 20, 30, ..., 110 highest energy events with a corresponding minimum energy threshold of about 51 EeV. The minimum P-values found were 13.5% using the 2pt-L method, 1.0% using the 2pt+ method and 1.1% using the 3pt method for the highest 100 energy events. In view of the multiple (correlated) scans performed on the data set, these catalog-independent methods do not yield strong evidence of anisotropy in the highest energy cosmic rays.

  17. A search for anisotropy in the arrival directions of ultra high energy cosmic rays recorded at the Pierre Auger Observatory

    Energy Technology Data Exchange (ETDEWEB)

    Abreu, P.; Andringa, S. [LIP and Instituto Superior Técnico, Technical University of Lisbon (Portugal); Aglietta, M. [Istituto di Fisica dello Spazio Interplanetario (INAF), Università di Torino and Sezione INFN, Torino (Italy); Ahlers, M. [University of Wisconsin, Madison, WI (United States); Ahn, E.J. [Fermilab, Batavia, IL (United States); Albuquerque, I.F.M. [Universidade de São Paulo, Instituto de Física, São Paulo, SP (Brazil); Allard, D. [Laboratoire AstroParticule et Cosmologie (APC), Université Paris 7, CNRS-IN2P3, Paris (France); Allekotte, I. [Centro Atómico Bariloche and Instituto Balseiro (CNEA-UNCuyo-CONICET), San Carlos de Bariloche (Argentina); Allen, J. [New York University, New York, NY (United States); Allison, P. [Ohio State University, Columbus, OH (United States); Almela, A. [Universidad Tecnológica Nacional - Facultad Regional Buenos Aires, Buenos Aires (Argentina); Castillo, J. Alvarez [Universidad Nacional Autonoma de Mexico, Mexico, D.F. (Mexico); Alvarez-Muñiz, J. [Universidad de Santiago de Compostela (Spain); Ambrosio, M.; Aramo, C. [Università di Napoli ' Federico II' and Sezione INFN, Napoli (Italy); Aminaei, A. [IMAPP, Radboud University Nijmegen (Netherlands); Anchordoqui, L. [University of Wisconsin, Milwaukee, WI (United States); Antici' c, T. [Rudjer Boškovi' c Institute, 10000 Zagreb (Croatia); Arganda, E. [IFLP, Universidad Nacional de La Plata and CONICET, La Plata (Argentina); Arqueros, F., E-mail: auger_spokesperson@fnal.gov [Universidad Complutense de Madrid, Madrid (Spain); Collaboration: Pierre Auger Collaboration; and others

    2012-04-01

    Observations of cosmic ray arrival directions made with the Pierre Auger Observatory have previously provided evidence of anisotropy at the 99% CL using the correlation of ultra high energy cosmic rays (UHECRs) with objects drawn from the Véron-Cetty Véron catalog. In this paper we report on the use of three catalog independent methods to search for anisotropy. The 2pt–L, 2pt+ and 3pt methods, each giving a different measure of self-clustering in arrival directions, were tested on mock cosmic ray data sets to study the impacts of sample size and magnetic smearing on their results, accounting for both angular and energy resolutions. If the sources of UHECRs follow the same large scale structure as ordinary galaxies in the local Universe and if UHECRs are deflected no more than a few degrees, a study of mock maps suggests that these three methods can efficiently respond to the resulting anisotropy with a P-value = 1.0% or smaller with data sets as few as 100 events. Using data taken from January 1, 2004 to July 31, 2010 we examined the 20,30,...,110 highest energy events with a corresponding minimum energy threshold of about 49.3 EeV. The minimum P-values found were 13.5% using the 2pt-L method, 1.0% using the 2pt+ method and 1.1% using the 3pt method for the highest 100 energy events. In view of the multiple (correlated) scans performed on the data set, these catalog-independent methods do not yield strong evidence of anisotropy in the highest energy cosmic rays.

  18. Energy Spectrum Of Nonthermal Electrons Accelerated At A Plane Shock

    CERN Document Server

    Kang, Hyesung

    2011-01-01

    We calculate the energy spectra of cosmic ray (CR) protons and electrons at a plane shock with quasi-parallel magnetic fields, using time-dependent, diffusive shock acceleration (DSA) simulations, including energy losses via synchrotron emission and Inverse Compton (IC) scattering. A thermal leakage injection model and a Bohm type diffusion coefficient are adopted. The electron spectrum at the shock becomes steady after the DSA energy gains balance the synchrotron/IC losses, and it cuts off at the equilibrium momentum p_{eq}. In the postshock region the cutoff momentum of the electron spectrum decreases with the distance from the shock due to the energy losses and the thickness of the spatial distribution of electrons scales as p^{-1}. Thus the slope of the downstream integrated spectrum steepens by one power of p for p_{br}spectrum exhibit a concave curvature and...

  19. Energy Spectrum of Anyons in a Magnetic Field

    CERN Document Server

    Illuminati, F

    1993-01-01

    For the many-anyon system in external magnetic field, we derive the energy spectrum as an exact solution of the quantum eigenvalue problem with particular topological constraints. Our results agree with the numerical spectra recently obtained for the 3- and the 4-anyon systems.

  20. Energy Spectrum of Anyons in a Magnetic Field

    OpenAIRE

    Illuminati, Fabrizio

    1992-01-01

    For the many-anyon system in external magnetic field, we derive the energy spectrum as an exact solution of the quantum eigenvalue problem with particular topological constraints. Our results agree with the numerical spectra recently obtained for the 3- and the 4-anyon systems.

  1. Compressive sampling for energy spectrum estimation of turbulent flows

    CERN Document Server

    Adalsteinsson, Gudmundur F

    2014-01-01

    Recent results from compressive sampling (CS) have demonstrated that accurate reconstruction of sparse signals often requires far fewer samples than suggested by the classical Nyquist--Shannon sampling theorem. Typically, signal reconstruction errors are measured in the $\\ell^2$ norm and the signal is assumed to be sparse, compressible or having a prior distribution. Our spectrum estimation by sparse optimization (SpESO) method uses prior information about isotropic homogeneous turbulent flows with power law energy spectra and applies the methods of CS to 1-D and 2-D turbulence signals to estimate their energy spectra with small logarithmic errors. SpESO is distinct from existing energy spectrum estimation methods which are based on sparse support of the signal in Fourier space. SpESO approximates energy spectra with an order of magnitude fewer samples than needed with Shannon sampling. Our results demonstrate that SpESO performs much better than lumped orthogonal matching pursuit (LOMP), and as well or bette...

  2. Exact energy spectrum for models with equally spaced point potentials

    OpenAIRE

    Caudrelier, V.; Crampe, N.

    2006-01-01

    We describe a non-perturbative method for computing the energy band structures of one-dimensional models with general point potentials sitting at equally spaced sites. This is done thanks to a Bethe ansatz approach and the method is applicable even when periodicity is broken, that is when Bloch's theorem is not valid any more. We derive the general equation governing the energy spectrum and illustrate its use in various situations. In particular, we get exact results for boundary effects. We ...

  3. Average Anisotropy Characteristics of High Energy Cosmic Ray Particles and Geomagnetic Disturbance Index Ap

    Indian Academy of Sciences (India)

    C. M. Tiwari; D. P. Tiwari; Ajay K. Pandey; Pankaj K. Shrivastava

    2005-12-01

    The average characteristics of the diurnal and semi-diurnal anisotropy of cosmic ray intensity at relativistic energies have been obtained by using data from the worldwide grid of neutron monitor for the period 1989 to 1996. The complex behaviour of the diurnal amplitudes and time of maxima (phase) and its association with the Ap index on a long-term and day-to-day basis have been studied. Even though the general characteristics, on a yearly average basis, have not changed significantly during this period, both the diurnal and semi-diurnal amplitudes and phases vary significantly, besides significant changes being observed for different interplanetary conditions on a short-term basis. It is found that the relationship between the Ap index and the diurnal vector is out of phase during the period 1991 to 1995. On a long-term basis, the correlation of diurnal variation with Ap index has been found to vary during the solar cycle. On a short-term basis, it has been observed that the high Ap days are usually associated with higher amplitudes with phase shifted to earlier hours.

  4. ENERGY SPECTRUM AND CHEMICAL COMPOSITION OF ULTRAHIGH ENERGY COSMIC RAYS FROM SEMI-RELATIVISTIC HYPERNOVAE

    Energy Technology Data Exchange (ETDEWEB)

    Liu Ruoyu; Wang Xiangyu [Department of Astronomy, Nanjing University, Nanjing 210093 (China)

    2012-02-10

    It has been suggested that hypernova remnants, with a substantial amount of energy in semi-relativistic ejecta, can accelerate intermediate mass or heavy nuclei to ultrahigh energies and provide a sufficient amount of energy in cosmic rays to account for the observed flux. We here calculate the expected energy spectrum and chemical composition of ultrahigh energy cosmic rays from such semi-relativistic hypernovae. With a chemical composition equal to that of the hypernova ejecta and a flat or hard spectrum for cosmic rays at the sources, the spectrum and composition of the propagated cosmic rays observed at the Earth can be compatible with the measurements by the Pierre Auger Observatory.

  5. Direct measurement of anisotropy of interfacial free energy from grain boundary groove morphology in transparent organic metal analong systems

    Energy Technology Data Exchange (ETDEWEB)

    Rustwick, Bryce A. [Iowa State Univ., Ames, IA (United States)

    2005-01-01

    Both academia and industry alike have paid close attention to the mechanisms of microstructural selection during the solidification process. The forces that give rise to and the principles which rule the natural selection of particular morphologies are important to understanding and controlling new microstructures. Interfacial properties play a very crucial role to the selection of such microstructure formation. In the solidification of a metallic alloy, the solid-liquid interface is highly mobile and responds to very minute changes in the local conditions. At this interface, the driving force must be large enough to drive solute diffusion, maintain local curvature, and overcome the kinetic barrier to move the interface. Therefore, the anisotropy of interfacial free energy with respect to crystallographic orientation is has a significant influence on the solidification of metallic systems. Although it is generally accepted that the solid-liquid interfacial free energy and its associated anisotropy are highly important to the overall selection of morphology, the confident measurement of these particular quantities remains a challenge, and reported values are scarce. Methods for measurement of the interfacial free energy include nucleation experiments and grain boundary groove experiments. The predominant method used to determine anisotropy of interfacial energy has been equilibrium shape measurement. There have been numerous investigations involving grain boundaries at a solid-liquid interface. These studies indicated the GBG could be used to describe various interfacial energy values, which affect solidification. Early studies allowed for an estimate of interfacial energy with respect to the GBG energy, and finally absolute interfacial energy in a constant thermal gradient. These studies however, did not account for the anisotropic nature of the material at the GBG. Since interfacial energy is normally dependent on orientation of the crystallographic plane of the

  6. Study of Small-Scale Anisotropy of Ultrahigh Energy Cosmic Rays Observed in Stereo by HiRes

    CERN Document Server

    Abbasi, R U; Amann, J F; Archbold, G; Atkins, R; Bellido, J A; Belov, K; Belz, J W; Ben-Zvi, S Y; Bergman, D R; Boyer, J H; Burt, G W; Cao, Z; Clay, R W; Connolly, B M; Dawson, B R; Deng, W; Fedorova, Y; Findlay, J; Finley, C B; Hanlon, W F; Hoffman, C M; Holzscheiter, M H; Hughes, G A; Jui, C C H; Kim, K; Kirn, M A; Knapp, B C; Loh, E C; Maestas, M M; Manago, N; Mannel, E J; Marek, L J; Martens, K; Matthews, J A J; Matthews, J N; O'Neill, A; Painter, C A; Perera, L P; Reil, K; Riehle, R; Roberts, M D; Sasaki, M; Schnetzer, S R; Seman, M; Simpson, K M; Sinnis, G; Smith, J D; Snow, R; Sokolsky, P; Song, C; Springer, R W; Stokes, B T; Thomas, J R; Thomas, S B; Thomson, G B; Tupa, D; Westerhoff, S; Wiencke, L R; Zech, A

    2004-01-01

    The High Resolution Fly's Eye (HiRes) experiment is an air fluorescence detector which, operating in stereo mode, has a typical angular resolution of 0.6 degrees and is sensitive to cosmic rays with energies above 10^18 eV. HiRes is thus an excellent instrument for the study of the arrival directions of ultrahigh energy cosmic rays. We present the results of a search for anisotropies in the distribution of arrival directions on small scales (10^19 eV). The search is based on data recorded between 1999 December and 2004 January, with a total of 271 events above 10^19 eV. No small-scale anisotropy is found, and the strongest clustering found in the HiRes stereo data is consistent at the 52% level with the null hypothesis of isotropically distributed arrival directions.

  7. Fast Two-Step Energy Detection for Spectrum Sensing

    Directory of Open Access Journals (Sweden)

    Meiling Lai

    2015-01-01

    Full Text Available Spectrum sensing is one of the key tasks in cognitive radio. This paper proposes a fast two-step energy detection (FED algorithm for spectrum sensing via improving the sampling process of conventional energy detection (CED. The algorithm adaptively selects N-point or 2N-point sampling by comparing its observed energy with prefixed double thresholds, and thereby is superior in sampling time and detection speed. Moreover, under the constraint of constant false alarm, this paper optimizes the thresholds from maximizing detection probability point of view. Theoretical analyses and simulation results show that, compared with CED, the proposed FED can achieve significant gain in detection speed at the expense of slight accuracy loss. Specifically, within high signal-to-noise ratio regions, as much as 25% of samples can be reduced.

  8. On the energy spectrum of the electroweak Pomeron

    CERN Document Server

    Bartels, Jochen; Siddikov, Marat

    2016-01-01

    In this paper we study the high energy behaviour of Electroweak Standard Model for a nonzero Weinberg angle $\\theta_{W}$. We evaluate the spectrum of the electroweak pomeron and demonstrate that the leading intercept is given by $\\alpha _{\\rm e.w.}4 \\ln 2$ and does not depend on the mixing angle $\\theta_{W}$. Due to its very small numerical value, we conclude that the high energy behaviour of electroweak theory cannot be discussed without including the QCD Pomeron which, at sufficiently large energies, will dominate.

  9. AGASA energy spectrum and the GZK cut-off

    Energy Technology Data Exchange (ETDEWEB)

    Capdevielle, J.N.; Cohen, F. [APC Astroparticules et Cosmologie, Univ. de Paris 7, 10 rue Alice Domont et Leonie Duquet, 75205 Paris (France); Szabelska, B.; Szabelski, J. [The Andrzej Soltan Institute for Nuclear Studies, Cosmic Ray Laboratory 90-950 Lodz 1, POBox 447 (Poland)

    2009-12-15

    We discuss primary CR energy estimations for very large surface EAS experiments. We show that the procedure of energy determination via the relation to particle densities at 600 m from the shower axis, rho{sub 600}, requires a specific treatment for inclined cascades when the maximum of EAS development is close to the array. As follows from simulations and cascade theory, using an exponential function for rho{sub 600} conversion from inclined to vertical showers is no longer valid and leads to an overestimate of the primary energy. We present a procedure to reconstruct the primary spectrum that can reduce the discrepancy between the results of fluorescence experiments and surface arrays.

  10. Large scale anisotropy studies of ultra high energy cosmic rays using data taken with the surface detector of the Pierre Auger Observatory

    Energy Technology Data Exchange (ETDEWEB)

    Grigat, Marius

    2011-06-10

    The distribution of arrival directions of cosmic rays is remarkably uniform over the complete spectrum of energies. At large angular scales only tiny deviations from isotropy have been observed and huge statistics are required to quantify the corresponding amplitudes. The measurement of cosmic rays with energies above 10{sup 15} eV is only feasible with large, earthbound observatories: The cosmic ray primary particles initiate cascades of secondary particles in the Earth's atmosphere. Every aspect of the development of these air showers down to the measurement of the resulting particles at ground level needs to be well understood and controlled in order to precisely reconstruct the properties of the primary particle. The development of air showers is subject to systematic distortions caused by the magnetic field of the Earth. Both this and other local effects are capable of inducing false anisotropy into the distribution of arrival directions. In this thesis, the effect of the geomagnetic field on the energy measurement is modelled and quantified; consequently, a correction of the energy estimator is derived. Furthermore, a method is introduced to fit dipolar patterns to the distribution of arrival directions of cosmic rays as observed from the field of view of the surface detector of the Pierre Auger Observatory. After correcting for all relevant local effects the method is applied to data and the parameters of a potentially underlying dipole are determined and evaluated. (orig.)

  11. Large scale anisotropy studies of ultra high energy cosmic rays using data taken with the surface detector of the Pierre Auger Observatory

    International Nuclear Information System (INIS)

    The distribution of arrival directions of cosmic rays is remarkably uniform over the complete spectrum of energies. At large angular scales only tiny deviations from isotropy have been observed and huge statistics are required to quantify the corresponding amplitudes. The measurement of cosmic rays with energies above 1015 eV is only feasible with large, earthbound observatories: The cosmic ray primary particles initiate cascades of secondary particles in the Earth's atmosphere. Every aspect of the development of these air showers down to the measurement of the resulting particles at ground level needs to be well understood and controlled in order to precisely reconstruct the properties of the primary particle. The development of air showers is subject to systematic distortions caused by the magnetic field of the Earth. Both this and other local effects are capable of inducing false anisotropy into the distribution of arrival directions. In this thesis, the effect of the geomagnetic field on the energy measurement is modelled and quantified; consequently, a correction of the energy estimator is derived. Furthermore, a method is introduced to fit dipolar patterns to the distribution of arrival directions of cosmic rays as observed from the field of view of the surface detector of the Pierre Auger Observatory. After correcting for all relevant local effects the method is applied to data and the parameters of a potentially underlying dipole are determined and evaluated. (orig.)

  12. Sharp vorticity gradients in two-dimensional turbulence and the energy spectrum

    DEFF Research Database (Denmark)

    Kuznetsov, E.A.; Naulin, Volker; Nielsen, Anders Henry;

    2010-01-01

    Formation of sharp vorticity gradients in two-dimensional (2D) hydrodynamic turbulence and their influence on the turbulent spectra are considered. The analog of the vortex line representation as a transformation to the curvilinear system of coordinates moving together with the di-vorticity lines...... is developed and compressibility of this mapping appears as the main reason for the formation of the sharp vorticity gradients at high Reynolds numbers. In the case of strong anisotropy the sharp vorticity gradients can generate spectra which fall off as k −3 at large k, which appear to take the same form...... as the Kraichnan spectrum for the enstrophy cascade. For turbulence with weak anisotropy the k dependence of the spectrum due to the sharp gradients coincides with the Saffman spectrum: E(k) ~ k −4. Numerical investigations of decaying turbulence reveal exponential growth of di-vorticity with a spatial distributed...

  13. Decay energy of 55Fe from its inner Bremsstrahlung spectrum

    Indian Academy of Sciences (India)

    S L Keshava; K Gopala; P Venkataramaiah

    2001-06-01

    Several measurements of decay energy using the inner Bremsstrahlung spectrum (IB) due to radiative electron capture in 55Fe has been made. But the results are not uniform. Hence another attempt has been made at the same. Experimental data was obtained with a 4.445 cm. dia × 5.08 cm thick NaI (Tl) detector. It was subjected to suitable statistical treatment and various corrections using Liden and Starfelt procedure. The corrected spectrum agrees well with the Glauber and Martin theory for 1s electron capture beyond 100 keV. From the Jauch plot, the decay energy of 232.36 ± 0.64 keV was obtained.

  14. Calculating the role of composition in the anisotropy of solid-liquid interface energy using phase-field-crystal theory

    Science.gov (United States)

    Jugdutt, Bernadine A.; Ofori-Opoku, Nana; Provatas, Nikolas

    2015-10-01

    This work uses Ginzburg-Landau theory derived from a recent structural phase-field-crystal model of binary alloys developed by the authors to study the roles of concentration, temperature, and pressure on the interfacial energy anisotropy of a solid-liquid front. It is found that the main contribution to the change in anisotropy with concentration arises from a change in preferred crystallographic orientation controlled by solute-dependent changes in the two-point density correlation function of a binary alloy, a mechanism that leads to such phenomena as solute-induced elastic strain and dislocation-assisted solute clustering. Our results are consistent with experimental observations in recent studies by Rappaz et al. [J. Fife, P. Di Napoli, and M. Rappaz, Metall. Mater. Trans. A 44, 5522 (2013), 10.1007/s11661-013-1912-7]. This is the first PFC work, to our knowledge, to incorporate temperature, pressure, and density into the thermodynamic description of alloys.

  15. Energy-Efficient Spectrum Sensing for Cognitive Radio Networks

    NARCIS (Netherlands)

    Maleki, S.

    2013-01-01

    Dynamic spectrum access employing cognitive radios has been proposed, in order to opportunistically use underutilized spectrum portions of a heavily licensed electromagnetic spectrum. Cognitive radios opportunistically share the spectrum, while avoiding any harmful interference to the primary licens

  16. Exact Ultra Cold Neutrons' Energy Spectrum in Gravitational Quantum Mechanics

    CERN Document Server

    Pedram, Pouria

    2013-01-01

    We find exact energy eigenvalues and eigenfunctions of the quantum bouncer in the presence of the minimal length uncertainty and the maximal momentum. This form of Generalized (Gravitational) Uncertainty Principle (GUP) agrees with various theories of quantum gravity and predicts a minimal length uncertainty proportional to $\\hbar\\sqrt{\\beta}$ and a maximal momentum proportional to $1/\\sqrt{\\beta}$, where $\\beta$ is the deformation parameter. We also find the semiclassical energy spectrum and discuss the effects of this GUP on the transition rate of the ultra cold neutrons in gravitational spectrometers. Then, based on the Nesvizhevsky's famous experiment, we obtain an upper bound on the dimensionless GUP parameter.

  17. Exact ultra cold neutrons' energy spectrum in gravitational quantum mechanics

    Science.gov (United States)

    Pedram, Pouria

    2013-10-01

    We find exact energy eigenvalues and eigenfunctions of the quantum bouncer in the presence of the minimal length uncertainty and the maximal momentum. This form of Generalized (Gravitational) Uncertainty Principle (GUP) agrees with various theories of quantum gravity and predicts a minimal length uncertainty proportional to and a maximal momentum proportional to , where β is the deformation parameter. We also find the semiclassical energy spectrum and discuss the effects of this GUP on the transition rate of the ultra cold neutrons in gravitational spectrometers. Then, based on Nesvizhevsky's famous experiment, we obtain an upper bound on the dimensionless GUP parameter.

  18. Exact energy spectrum for models with equally spaced point potentials

    Science.gov (United States)

    Caudrelier, V.; Crampé, N.

    2006-03-01

    We describe a non-perturbative method for computing the energy band structures of one-dimensional models with general point potentials sitting at equally spaced sites. This is done thanks to a Bethe ansatz approach and the method is applicable even when periodicity is broken, that is when Bloch's theorem is not valid any more. We derive the general equation governing the energy spectrum and illustrate its use in various situations. In particular, we get exact results for boundary effects. We also study non-perturbatively the effects of impurities in such systems. Finally, we discuss the possibility of including interactions between the particles of these systems.

  19. LARGE GAMMA ANISOTROPY OBSERVED IN THE CF-252 SPONTANEOUS-FISSION PROCESS

    NARCIS (Netherlands)

    VANDERPLOEG, H; BACELAR, JC; VANDENBERG, T; IACOB, VE; JONGMAN, [No Value; VANDERWOUDE, A

    1992-01-01

    The energy spectrum and the angular dependence relative to the fission direction of photons in the energy region between 2 and 40 MeV have been measured for the spontaneous fission of Cf-252. A large anisotropy was found in the energy region 8 to 12 MeV implying that photons in this region are emitt

  20. The energy spectrum and the optical absorption spectrum of C{sub 60} fullerene within the Hubbard model

    Energy Technology Data Exchange (ETDEWEB)

    Silant’ev, A. V., E-mail: kvvant@rambler.ru [Mari State University (Russian Federation)

    2015-10-15

    Anticommutator Green’s functions and the energy spectrum of C{sub 60} fullerene are calculated in the approximation of static fluctuations within the Hubbard model. On the basis of this spectrum, an interpretation is proposed for the experimentally observed optical absorption bands of C{sub 60} fullerene. The parameters of C{sub 60} fullerene that characterize it within the Hubbard model are calculated by the optical absorption spectrum.

  1. The high energy spectrum of 3C 273

    CERN Document Server

    Esposito, V; Jean, P; Tramacere, A; Türler, M; Lähteenmäki, A; Tornikoski, M

    2015-01-01

    Aims. The high energy spectrum of 3C 273 is usually understood in terms of inverse-Compton emission in a relativistic leptonic jet. This model predicts variability patterns and delays that could be tested with simultaneous observations from the radio to the GeV range. Methods. The instruments IBIS, SPI, JEM-X on board INTEGRAL, PCA on board RXTE, and LAT on board Fermi have enough sensitivity to follow the spectral variability of 3C 273 from the keV to the GeV. We looked for correlations between the different energy bands, including radio data at 37 GHz collected at the Mets\\"ahovi Radio Observatory and built quasi-simultaneous multiwavelength spectra in the high energy domain when the source is flaring either in the X-rays or in the {\\gamma} rays. Results. Both temporal and spectral analysis suggest a two-component model to explain the complete high energy spectrum. X-ray emission is likely dominated by a Seyfert-like component while the {\\gamma}-ray emission is dominated by a blazar-like component produced ...

  2. Influence of some factors on alpha energy spectrum of 241Am fire alarm source

    Institute of Scientific and Technical Information of China (English)

    1999-01-01

    Several primary factors influencing the alpha energy spectrum of 241Am fire alarm source have been studied in order to get betteralpha energy spectrum.The results show that the homogeneity andthe thickness of metal surface coat and the size of active area of thesource have considerable influence on the alpha energy spectrum of thesource.

  3. Universal Raising and Lowering Operators for a Discrete Energy Spectrum

    Science.gov (United States)

    Torres-Vega, Gabino

    2016-06-01

    We consider the first-order finite-difference expression of the commutator between d / dx and x. This is the appropriate setting in which to propose commutators and time operators for a quantum system with an arbitrary potential function and a discrete energy spectrum. The resulting commutators are identified as universal lowering and raising operators. We also find time operators which are finite-difference derivations with respect to the energy. The matrix elements of the commutator in the energy representation are analyzed, and we find consistency with the equality [hat{T},hat{H}]=ihbar . We apply the theory to the particle in an infinite well and for the Harmonic oscillator as examples.

  4. ENERGY EFFICIENT COOPERATIVE SPECTRUM SENSING IN COGNITIVE RADIO

    Directory of Open Access Journals (Sweden)

    Ramzi Saifan

    2016-03-01

    Full Text Available Sensing in cognitive radio (CR protects the primary user (PU from bad interference. Therefore, it is assumed to be a requirement. However, sensing has two main challenges; first the CR is required to sense the PU under very low signal to noise ratios which will take longer sensing time, and second, some CR nodes may suffer from deep fading and shadowing effects. Cooperative spectrum sensing (CSS is supposed to solve these challenges. However, CSS adds extra energy consumption due to CRs send the sensing result to the fusion center and receive the final decision from the fusion center. This is in addition to the sensing energy itself. Therefore, CSS may consume considerable energy out of the battery of the CR node. Therefore in this paper, we try to find jointly the sensing time required from each CR node and the number of CR nodes who should perform sensing such that the energy and energy efficiency (i.e., ratio of throughput to energy consumed are optimized. Simulation results show that the joint optimization achieves better in terms of energy efficiency than other approaches that perform separate optimization.

  5. Energy spectrum for a strongly correlated network and local magnetism

    Institute of Scientific and Technical Information of China (English)

    Li-li LIU; Qiao BI

    2009-01-01

    In this work, we consider a quantum strongly correlated network described by an Anderson s-d mixing model. By introducing the Green function on the projected formalism of the Schrieffer and Wolf transformation, the energy spectrum of the system can be obtained. Using this result we calculate the survivability distribution of the network and discuss the local magnetism in the network, which shows that the survivability is an important statistical characteristic quantity not just to reflect the network topological property but also dynamics.

  6. The toes of the ultra high energy cosmic ray spectrum

    OpenAIRE

    Harari, Diego; Mollerach, Silvia; Roulet, Esteban

    1999-01-01

    We study the effects of the galactic magnetic field on the ultra high energy cosmic ray propagation. We show that the deflections of the cosmic ray trajectories can have many important implications such as (de)magnification of the cosmic ray fluxes by lensing effects (which can modify the spectrum of individual sources), the formation of multiple images of a source or the existence of regions of the sky to which the Earth is almost blind. The appearance of image pairs is related to the existe...

  7. Anisotropy and chemical composition of ultra-high energy cosmic rays using arrival directions measured by the Pierre Auger Observatory

    OpenAIRE

    Arganda, E.; Arqueros Martínez, Fernando; Blanco Ramos, Francisco; García Pinto, Diego; Ortiz Ramis, Montserrat; Rosado Vélez, Jaime; Vázquez Peñas, José Ramón

    2011-01-01

    The Pierre Auger Collaboration has reported. evidence for anisotropy in the distribution of arrival directions of the cosmic rays with energies E > E-th = 5.5 x 10(19) eV. These show a correlation with the distribution of nearby extragalactic objects, including an apparent excess around the direction of Centaurus A. If the particles responsible for these excesses at E > E-th are heavy nuclei with charge Z, the proton component of the sources should lead to excesses in the same regions at ener...

  8. Chandra High Energy Transmission Grating Spectrum of AE Aquarii

    CERN Document Server

    Mauche, Christopher W

    2009-01-01

    (Abridged) The results of a Chandra X-ray Observatory High-Energy Transmission Grating (HETG) observation of the nova-like cataclysmic binary AE Aqr are described. First, the X-ray spectrum is that of an optically thin multi-temperature thermal plasma; the X-ray emission lines are broad, with widths that increase with the line energy, from sigma~1 eV for O VIII to sigma~5.5 eV for Si XIV; the X-ray spectrum is reasonably well fit by a plasma model with a Gaussian emission measure distribution that peaks at log T(K)=7.16, has a width sigma=0.48, an Fe abundance equal to 0.44 times solar, and other metal (primarily Ne, Mg, and Si) abundances equal to 0.76 times solar; and for a distance d=100 pc, the total emission measure EM=8.0E53 cm^-3 and the 0.5-10 keV luminosity L_X=1.1E31 erg/s. Second, based on the f/(i+r) flux ratios of the forbidden (f), intercombination (i), and recombination (r) lines of the He alpha triplets of N VI, O VII, and Ne IX measured by Itoh et al. in the XMM-Newton Reflection Grating Spec...

  9. Sensitivity of EAS measurements to the energy spectrum of muons

    CERN Document Server

    Espadanal, J; Conceição, R

    2016-01-01

    We have studied how the energy spectrum of muons at production affects some of the most common measurements related to muons in extensive air shower studies, namely, the number of muons at the ground, the slope of the lateral distribution of muons, the apparent muon production depth, and the arrival time delay of muons at ground. We found that by changing the energy spectrum by an amount consistent with the difference between current models (namely EPOS-LHC and QGSjet-II.04), the muon surface density at ground increases $5\\%$ at $20^\\circ$ zenith angle and $17\\%$ at $60^\\circ$ zenith angle. This effect introduces a zenith angle dependence on the reconstructed number of muons which might be experimentally observed. The maximum of the muon production depth distribution at $40^\\circ$ increases $\\sim10\\text{ g/cm}^2$ and $\\sim0\\text{ g/cm}^2$ at $60^\\circ$, which, from pure geometrical considerations, increases the arrival time delay of muons. There is an extra contribution to the delay due to the subluminal velo...

  10. The cosmic-ray positron energy spectrum measured by PAMELA

    CERN Document Server

    Adriani, O; Bazilevskaya, G A; Bellotti, R; Bianco, A; Boezio, M; Bogomolov, E A; Bongi, M; Bonvicini, V; Bottai, S; Bruno, A; Cafagna, F; Campana, D; Carbone, R; Carlson, P; Casolino, M; Castellini, G; De Donato, C; De Santis, C; De Simone, N; Di Felice, V; Formato, V; Galper, A M; Karelin, A V; Koldashov, S V; Koldobskiy, S A; Krutkov, S Y; Kvashnin, A N; Leonov, A; Malakhov, V; Marcelli, L; Martucci, M; Mayorov, A G; Menn, W; Merge', M; Mikhailov, V V; Mocchiutti, E; Monaco, A; Mori, N; Munini, R; Osteria, G; Palma, F; Papini, P; Pearce, M; Picozza, P; Pizzolotto, C; Ricci, M; Ricciarini, S B; Rossetto, L; Sarkar, R; Scotti, V; Simon, M; Sparvoli, R; Spillantini, P; Stochaj, S J; Stockton, J C; Stozhkov, Y I; Vacchi, A; Vannuccini, E; Vasilyev, G I; Voronov, S A; Yurkin, Y T; Zampa, G; Zampa, N; Zverev, V G

    2013-01-01

    Precision measurements of the positron component in the cosmic radiation provide important information about the propagation of cosmic rays and the nature of particle sources in our Galaxy. The satellite-borne experiment PAMELA has been used to make a new measurement of the cosmic-ray positron flux and fraction that extends previously published measurements up to 300 GeV in kinetic energy. The combined measurements of the cosmic-ray positron energy spectrum and fraction provide a unique tool to constrain interpretation models. During the recent solar minimum activity period from July 2006 to December 2009 approximately 24500 positrons were observed. The results cannot be easily reconciled with purely secondary production and additional sources of either astrophysical or exotic origin may be required.

  11. Study of the Solar Anisotropy for Cosmic Ray Primaries of about 200 GeV Energy with the L3+C Muon Detector

    CERN Document Server

    Achard, P; Aguilar-Benitez, M; van den Akker, M; Alcaraz, J; Alemanni, G; Allaby, J; Aloisio, A; Alviggi, M G; Anderhub, H; Andreev, Valery P; Anselmo, F; Arefev, A; Azemoon, T; Aziz, T; Bagnaia, P; Bajo, A; Baksay, G; Baksay, L; Bahr, J; Baldew, S V; Banerjee, S; Banerjee, Sw; Barczyk, A; Barillere, R; Bartalini, P; Basile, M; Batalova, N; Battiston, R; Bay, A; Becattini, F; Becker, U; Behner, F; Bellucci, L; Berbeco, R; Berdugo, J; Berges, P; Bertucci, B; Betev, B L; Biasini, M; Biglietti, M; Biland, A; Blaising, J J; Blyth, S C; Bobbink, G J; Bohm, A; Boldizsar, L; Borgia, B; Bottai, S; Bourilkov, D; Bourquin, M; Braccini, S; Branson, J G; Brochu, F; Burger, J D; Burger, W J; Cai, X D; Capell, M; Cara Romeo, G; Carlino, G; Cartacci, A; Casaus, J; Cavallari, F; Cavallo, N; Cecchi, C; Cerrada, M; Chamizo, M; Chiarusi, T; Chang, Y H; Chemarin, M; Chen, A; Chen, G; Chen, G M; Chen, H F; Chen, H S; Chiefari, G; Cifarelli, L; Cindolo, F; Clare, I; Clare, R; Coignet, G; Colino, N; Costantini, S; de la Cruz, B; Cucciarelli, S; van Dalen, J; de Asmundis, R; Deglon, P; Debreczeni, J; Degre, A; Dehmelt, K; Deiters, K; della Volpe, D; Delmeire, E; Denes, P; DeNotaristefani, F; De Salvo, A; Diemoz, M; Dierckxsens, M; Ding, L K; Dionisi, C; Dittmar, M; Doria, A; Dova, M T; Duchesneau, D; Duda, M; Duran, I; Echenard, B; Eline, A; El Hage, A; El Mamouni, H; Engler, A; Eppling, F J; Extermann, P; Faber, G; Falagan, M A; Falciano, S; Favara, A; Fay, J; Fedin, O; Felcini, M; Ferguson, T; Fesefeldt, H; Fiandrini, E; Field, J H; Filthaut, F; Fisher, W; Fisk, I; Forconi, G; Freudenreich, K; Furetta, C; Galaktionov, Iouri; Ganguli, S N; Garcia-Abia, Pablo; Gataullin, M; Gentile, S; Giagu, S; Gong, Z F; Grabosch, H J; Grenier, G; Grimm, O; Groenstege, H; Gruenewald, M W; Guida, M; Guo, Y N; Gupta, S; Gupta, V K; Gurtu, A; Gutay, L J; Haas, D; Haller, Ch; Hatzifotiadou, D; Hayashi, Y; He, Z X; Hebbeker, T; Herve, Alain; Hirschfelder, J; Hofer, H; Hohlmann, M; Holzner, G; Hou, S R; Huo, A X; Hu, Y; Ito, N; Jin, B N; Jing, C L; Jones, Lawrence W; de Jong, P; Josa-Mutuberria, I; Kantserov, V; Kaur, M; Kawakami, S; Kienzle-Focacci, M N; Kim, J K; Kirkby, Jasper; Kittel, W; Klimentov, A; Konig, A C; Kok, E; Korn, A; Kopal, M; Koutsenko, V; Kraber, M; Kuang, H H; Kraemer, R W; Kruger, A; Kuijpers, J; Kunin, A; Ladron de Guevara, P; Laktineh, I; Landi, G; Lebeau, M; Lebedev, A; Lebrun, P; Lecomte, P; Lecoq, P; Le Coultre, P; Le Goff, J M; Lei, Y; Leich, H; Leiste, R; Levtchenko, M; Levtchenko, P; Li, C; Li, L; Li, Z C; Likhoded, S; Lin, C H; Lin, W T; Linde, F L; Lista, L; Liu, Z A; Lohmann, W; Longo, E; Lu, Y S; Luci, C; Luminari, L; Lustermann, W; Ma, W G; Ma, X H; Ma, Y Q; Malgeri, L; Malinin, A; Mana, C; Mans, J; Martin, J P; Marzano, F; Mazumdar, K; McNeil, R R; Mele, S; Meng, X W; Merola, L; Meschini, M; Metzger, W J; Mihul, A; van Mil, A; Milcent, H; Mirabelli, G; Mnich, J; Mohanty, G B; Monteleoni, B; Muanza, y G S; Muijs, A J M; Musicar, B; Musy, M; Nagy, S; Nahnhauer, R; Naumov, V A; Natale, S; Napolitano, M; Nessi-Tedaldi, F; Newman, H; Nisati, A; Novak, T; Kluge, Hannelies; Ofierzynski, R; Organtini, G; Pal, I; Palomares, C; Paolucci, P; Paramatti, R; Parriaud, J -F; Passaleva, G; Patricelli, S; Paul, Thomas Cantzon; Pauluzzi, M; Paus, C; Pauss, F; Pedace, M; Pensotti, S; Perret-Gallix, D; Petersen, B; Piccolo, D; Pierella, F; Pieri, M; Pioppi, M; Piroue, P A; Pistolesi, E; Plyaskin, V; Pohl, M; Pojidaev, V; Pothier, J; Prokofev, D; Quartieri, J; Qing, C R; Rahal-Callot, G; Rahaman, Mohammad Azizur; Raics, P; Raja, N; Ramelli, R; Rancoita, P G; Ranieri, R; Raspereza, A; Ravindran, K C; Razis, P; Ren, D; Rescigno, M; Reucroft, S; Rewiersma, P; Riemann, y S; Riles, Keith; Roe, B P; Rojkov, A; Romero, L; Rosca, A; Rosemann, C; Rosenbleck, C; Rosier-Lees, S; Roth, Stefan; Rubio, J A; Ruggiero, G; Rykaczewski, H; Saidi, R; Sakharov, A; Saremi, S; Sarkar, S; Salicio, J; Sanchez, E; Schafer, C; Schegelsky, V; Schmitt, V; Schoeneich, B; Schopper, H; Schotanus, D J; Sciacca, C; Servoli, L; Shen, C Q; Shevchenko, S; Shivarov, N; Shoutko, V; Shumilov, E; Shvorob, A; Son, D; Souga, C; Spillantini, P; Steuer, M; Stickland, D P; Stoyanov, B; Straessner, A; Sudhakar, K; Sulanke, H; Sultanov, G; Sun, L Z; Sushkov, S; Suter, H; Swain, J D; Szillasi, Z; Tang, X W; Tarjan, P; Tauscher, L; Taylor, L; Tellili, B; Teyssier, D; Timmermans, Charles; Ting, Samuel C C; Ting, S M; Tonwar, S C; Toth, J; Trowitzsch, G; Tully, C; Tung, K L; Ulbricht, J; Unger, M; Valente, E; Verkooijen, H; Van de Walle, R T; Vasquez, R; Veszpremi, V; Vesztergombi, G; Vetlitsky, I; Vicinanza, D; Viertel, G; Villa, S; Vivargent, M; Vlachos, S; Vodopianov, I; Vogel, H; Vogt, H; Vorobev, I; Vorobyov, A A; Wadhwa, M; Wang, R G; Wang, Q; Wang, X L; Wang, X W; Wang, Z M; Weber, M; van Wijk, R; Wijnen, T A M; Wilkens, H; Wynhoff, S; Xia, L; Xu, Y P; Xu, J S

    2008-01-01

    Primary cosmic rays experience multiple deflections in the nonuniform galactic and heliospheric magnetic fields which may generate anisotropies. A study of anisotropies in the energy range between 100 and 500 GeV is performed. This energy range is not yet well explored. The L3 detector at the CERN electron-positron collider, LEP, is used for a study of the angular distribution of atmospheric muons with energies above 20 GeV. This distribution is used to investigate the isotropy of the time-dependent intensity of the primary cosmic-ray flux with a Fourier analysis. A small deviation from isotropy at energies around 200 GeV is observed for the second harmonics at the solar frequency. No sidereal anisotropy is found at a level above 10^-4. The measurements have been performed in the years 1999 and 2000.

  12. Low energy photon mimic of the tritium beta decay energy spectrum

    Science.gov (United States)

    Malabre-O'Sullivan, Neville

    Tritium is a radioactive hydrogen isotope that is typically produced via neutron interaction with heavy water (D2O), producing tritiated water (DTO). As a result of this, tritium accounts for roughly a third of all occupational exposures at a CANDU type nuclear power plant. This identifies a need to study the biological effects associated with tritium (and low energy electrons in general). However, there are complications regarding the dosimetry of tritium, as well as difficulties in handling and using tritium for the purposes of biophysics experiments. To avoid these difficulties, an experiment has been proposed using photons to mimic the beta decay energy spectrum of tritium. This would allow simulation of the radiation properties of tritium, so that a surrogate photon source can be used for biophysics experiments. Through experimental and computational means, this work has explored the use of characteristic x-rays of various materials to modify the output spectrum of an x-ray source, such that it mimics the tritium beta decay spectrum. Additionally, the resultant primary electron spectrum generated in water from an x-ray source was simulated. The results from this research have indicated that the use of characteristic x-rays is not a viable method for simulating a tritium source. Also, the primary electron spectrum generated in water shows some promise for simulating tritium exposure, however further work must be done to investigate the slowing down electron spectrum. Keywords: Tritium, MCNP, low energy electrons, biophysics, characteristic x-rays.

  13. Full Spectrum Diffused and Beamed Solar Energy Application Using Optical Fibre

    OpenAIRE

    Majumdar, M. R. Dutta; Das, Debasish

    2007-01-01

    Existing solar energy application systems use small fraction of full spectrum of solar energy. So attempts are made to show how full spectrum solar energy can be used for diffused and beamed form of incident solar energy. Luminescent Solar Concentrator (LSC) principle with optical fibre in diffused sun light and dielectric mirror separation technique with optical fibre in beamed form are discussed. Comparison of both the cases are done. Keywords: full spectrum, solar photonics, diffused solar...

  14. Energy Spectrum Extraction and Optimal Imaging via Dual-Energy Material Decomposition

    CERN Document Server

    Zhao, Wei; Zhang, Bo; Zhang, Qiude; Niu, Tianye

    2015-01-01

    Inferior soft-tissue contrast resolution is a major limitation of current CT scanners. The aim of the study is to improve the contrast resolution of CT scanners using dual-energy acquisition. Based on dual-energy material decomposition, the proposed method starts with extracting the outgoing energy spectrum by polychromatic forward projecting the material-selective images. The extracted spectrum is then reweighted to boost the soft-tissue contrast. A simulated water cylinder phantom with inserts that contain a series of six solutions of varying iodine concentration (range, 0-20 mg/mL) is used to evaluate the proposed method. Results show the root mean square error (RMSE) and mean energy difference between the extracted energy spectrum and the spectrum acquired using an energy-resolved photon counting detector(PCD), are 0.044 and 0.01 keV, respectively. Compared to the method using the standard energy-integrating detectors, dose normalized contrast-to-noise ratio (CNRD) for the proposed method are improved fro...

  15. Colossal anisotropy of the magnetic properties of doped lithium nitrodometalates

    Energy Technology Data Exchange (ETDEWEB)

    Antropov, Vladimir P [Ames Laboratory; Antonov, Victor N [Ames Laboratory

    2014-09-01

    We present a first-principles investigation of the electronic structure and physical properties of doped lithium nitridometalates Li2(Li1-xMx)N (LiMN) with M = Cr, Mn, Fe, Co, and Ni. The diverse properties include the equilibrium magnetic moments, magneto-crystalline anisotropy, magneto-optical Kerr spectra, and x-ray magnetic circular dichroism. We explain the colossal magnetic anisotropy in LiFeN by its unique electronic structure which ultimately leads to a series of unusual physical properties. The most unique property is a complete suppression of relativistic effects and freezing of orbital moments for in-plane orientation of the magnetization. This leads to the colossal spatial anisotropy of many magnetic properties including energy, Kerr, and dichroism effects. LiFeN is identified as an ultimate single-ion anisotropy system where a nearly insulating state can be produced by a spin orbital coupling alone. A very nontrivial strongly fluctuating and sign changing character of the magnetic anisotropy with electronic 3d-atomic doping is predicted theoretically. A large and highly anisotropic Kerr effect due to the interband transitions between atomic-like Fe 3d bands is found for LiFeN. A giant anisotropy of the x-ray magnetic circular dichroism for the Fe K spectrum and a very weak one for the Fe L2,3 spectra in LiFeN are also predicted.

  16. Neutron energy spectrum in graphite blankets of fusion reactors

    International Nuclear Information System (INIS)

    Neutron flux measurements were performed in a graphite stack and compared with calculations made with a two dimensional transport computer code. In the present work it is observed that the calculated spectrum in the elastic and inelastic scattering ranges (the first collision range in both cases), is sensitive to details of the angular distribution of these neutrons. Regarding the discrepancies in the elastic scattering range it is concluded that the microscopic cross section library ENDF/B-IV overestimates the large angle scattering (back scattering) as can be seen from comparison of measured and calculated spectra. The two most important conclusions of the present work are: 1. Inelastic scattering interaction of D-T neutrons in graphite cannot be calculated without a proper account of energy-angle correlation. 2. An experimental setup supplying monoenergetic collimated D-T neutrons constitutes a sensitive although indirect means for measuring angular distributions in inelastic and elastic scattering

  17. Effect of the fragment excitation energy distribution on the prompt fission neutron spectrum

    International Nuclear Information System (INIS)

    The effects of cascade emission of neutrons from a nucleus and of distribution of the initial excitation energy upon characteristics of the emission spectrum are studied. Calculations of the emission spectrum are made in the Weisskopf form in the constant temperature approximation. It has been elucidated that the cascade character of particle emission is not sufficient for the total spectrum to approach the maxwellian one. A dependence of the distorting function upon energy has been obtained. The calculation spectrum is compared with the experimental and with the Weisskopf spectra. A conclusion is drawn that the temperature dependence upon excitation energy is predominant in formation of a fission neutron spectrum

  18. Magnetization reversal of nanodots with different magnetic anisotropy and magnetostatic energy

    Energy Technology Data Exchange (ETDEWEB)

    Ivanov, Y P; Nefedev, K V; Iljin, A I; Pustovalov, E V; Chebotkevich, L A, E-mail: yivanov@phys.dvgu.ru [Institute of Physics and Informational Technologies, Far Eastern National University, Vladivostok, Sukhanova street 8, 690950 (Russian Federation)

    2011-01-01

    The arrays of circle and square nanodots were prepared by Ga{sup +} ion-beam etching of thing cobalt films with induced uniaxial magnetic anisotropy. The size of researched nanodots was d=600, 450 and 250 nm that equal or less then radius of ferromagnetic correlation for continuous Co film. The distances l=2d and 3d between center of nanodots in the arrays were taken. The interpretation of experimental magnetic force microscopy data was done by means of micromagnetic simulation and MFM-experiment simulation. Each nanodot of arrays with d=600 nm has multidomain structure at demagnetisation state for l=3d and magnetic vortex for l=2d. For arrays with size of element d<600 nm and l=2d and 3d at same condition occurred only vortex state.

  19. Measurement of the cosmic ray energy spectrum using hybrid events of the Pierre Auger Observatory

    NARCIS (Netherlands)

    Settimo, Mariangela; Abreu, P.; Aglietta, M.; Ahlers, M.; Ahn, E.J.; Albuquerque, IFM; Allard, D.; Allekotte, I.; Allen, J.; Allison, P.; Almela, A.; Alvarez Castillo, J.; Alvarez-Muiz, J.; Alves Batista, R.; Ambrosio, M.; Aminaei, A; Anchordoqui, L.; Andring, S.; Anticic, T.; Aramo, C.; Arqueros, F.; Asorey, H.; Assis, P.; Aublin, J.; Ave, M.; Avenier, M.; Avila, G.; Badescu, A.M.; Barber, K.B.; Barbosa, A.F.; Bardenet, R.; Baughman, B.; Bauml, J.; Baus, C.; Beatty, J.J.; Becker, K.H.; Belletoile, A.; Bellido, J.A.; BenZvi, S.; Berat, C.; Bertou, X.; Biermann, P.L.; Billoir, P.; Blanco, F.; Blanco, M.; Bleve, C.; Blumer, H.; Bohacova, M.; Boncioli, D.; Bonifazi, C.; Bonino, R.; Boroda, N.; Brack, J.; Brancus, I.; Brogueira, P.; Brown, W.C.; Bruijn, R.; Buchholz, P.; Bueno, A.; Buroker, L.; Burton, R.E.; Cabellero-Mora, K.S.; Caccianiga, B.; Caramete, L.; Caruso, R.; Castellina, A.; Catalano, O.; Cataldi, G.; Cazon, L.; Cester, R.; Chauvin, J.; Cheng, S.H.; Chiavassa, A.; Chinellato, J.A.; Chirinos Diaz, J.; Chudoba, J.; Cilmo, M.; Clay, R.W.; Cocciolo, G.; Collica, L.; Coluccia, M.R.; Conceicao, R.; Contreras, F.; Cook, H.; Cooper, M.J.; Coppens, J.; Cordier, A.; Coutu, S.; Covault, C.E.; Creusot, A.; Criss, A.; Cronin, J.; Curutiu, A.; Dagoret-Campagne, S.; Dallier, R.; Daniel, B.; Dasso, S.; Daumiller, K.; Dawson, B.R.; de Almeida, R.M.; De Domenico, M.; De Donato, C.; de Jong, S.J.; De La Vega, G.; de Mello Junior, W.J.M.; de Mello Neto, J.R.T.; De Mitri, I.; de Souza, V.; de Vries, K.D.; del Peral, L.; del Rio, M.; Deligny, O.; Dembinski, H.; Dhital, N.; Di Giulio, C.; Diaz Castro, M.L.; Diep, P.N.; Diogo, F.; Dobrigkeit, C.; Docters, W.; D'Olivo, J.C.; Dong, PN; Dorofeev, A.; dos Anjos, JC; Dova, M.T.; D'Urso, D.; Dutan, I.; Ebr, J.; Engel, R.; Erdmann, M.; Escobar, C.O.; Espadanal, J.; Etchegoyen, A.; Facal San Luis, P.; Falcke, H.; Fang, K.; Farrar, G.; Fauth, A.C.; Fazzini, N.; Ferguson, A.P.; Fick, B.; Figueira, J.M.; Filevich, A.; Filevich, A.; Fliescher, S.; Fracchiolla, C.E.; Fraenkel, E.D.; Fratu, O.; Frohlich, U.; Fuchs, B.; Gaior, R.; Gamarra, R.F.; Gambetta, S.; Garcia, B.; Garcia Roca, S.T.; Garcia-Gamez, D.; Garcia-Pinto, D.; Garilli, G.; Gascon Bravo, A.; Gemmeke, H.; Ghia, P.L.; Giller, M.; Gitto, J.; Glass, H.; Gold, M.S.; Golup, G.; Gomez Albarracin, F.; Gomez Berisso, M.; Gomez Vitale, P.F.; Goncalves, P.; Gonzalez, J.G.; Gookin, B.; Gorgi, A.; Gouffon, P.; Grashorn, E.; Grebe, S.; Griffith, N.; Grillo, A.F.; Guardincerri, Y.; Guarino, F.; Guedes, G.P.; Hansen, P.; Harari, D.; Harrison, T.A.; Harton, J.L.; Haungs, A.; Hebbeker, T.; Heck, D.; Herve, A.E.; Hill, G.C.; Hojvat, C.; Hollon, N.; Holmes, V.C.; Homola, P.; Horandel, J.R.; Horvath, P.; Hrabovsky, M.; Huber, D.; Huege, T.; Insolia, A.; Ionita, F.; Italiano, A.; Jansen, S.; Jarne, C.; Jiraskova, S.; Josebachuili, M.; Kadija, K.; Kampert, K.H.; Karhan, P.; Kasper, P.; Katkov, I.; Kegl, B.; Keilhauer, B.; Keivani, A.; Kelley, J.L.; Kemp, E.; Kieckhafer, R.M.; Klages, H.O.; Kleifges, M.; Kleinfeller, J.; Knapp, J.; Koang, D.H.; Kotera, K.; Krohm, N.; Kromer, O.; Kruppke-Hansen, D.; Kuempel, D.; Kulbartz, J.K.; Kunka, N.; La Rosa, G.; Lachaud, C.; LaHurd, D.; Latronico, L.; Lauer, R.; Lautridou, P.; Le Coz, S.; Leao, M.S.A.B.; Lebrun, D.; Lebrun, P.; Leigui de Oliveira, M.A.; Letessier-Selvon, A.; Lhenry-Yvon, I.; Link, K.; Lopez, R.; Lopez Aguera, A.; Louedec, K.; Lozano Bahilo, J.; Lu, L.; Lucero, A.; Ludwig, M.; Lyberis, H.; Maccarone, M.C.; Macolino, C.; Maldera, S.; Maller, J.; Mandat, D.; Mantsch, P.; Mariazzi, A.G.; Marin, J.; Marin, V.; Maris, I.C.; Marquez Falcon, H.R.; Marsella, G.; Martello, D.; Martinez, H.; Martinez Bravo, O.; Martraire, D.; Masias Meza, [No Value; Mathes, H.J.; Matthews, J.; Matthews, J.A.J.; Matthiae, G.; Maurel, D.; Maurizio, D.; Mazur, P.O.; Medina-Tanco, G.; Melissas, M.; Melo, D.; Menichetti, E.; Menshikov, A.; Mertsch, P.; Messina, S.; Meurer, C.; Meyhandan, R.; Mi'canovi'c, S.; Micheletti, M.I.; Minaya, I.A.; Miramonti, L.; Molina-Bueno, L.; Mollerach, S.; Monasor, M.; Monnier Ragaigne, D.; Montanet, F.; Morales, B.; Morello, C.; Moreno, J.C.; Mostafa, M.; Moura, C.A.; Muller, M.A.; Muller, G.; Munchmeyer, M.; Mussa, R.; Navarra, G.; Navarro, J.L.; Navas, S.; Necesal, P.; Nellen, L.; Nelles, A.; Neuser, J.; Nhung, P.T.; Niechciol, M.; Niemietz, L.; Nierstenhoefer, N.; Nitz, D.; Nosek, D.; Nozka, L.; Oehlschlager, J.; Olinto, A.; Ortiz, M.; Pacheco, N.; Pakk Selmi-Dei, D.; Palatka, M.; Pallotta, J.; Palmieri, N.; Parente, G.; Parizot, E.; Parra, A.; Pastor, S.; Paul, T.; Pech, M.; Pekala, J.; Pelayo, R.; Pepe, I.M.; Perrone, L.; Pesce, R.; Petermann, E.; Petrera, S.; Petrolini, A.; Petrov, Y.; Pfendner, C.; Piegaia, R.; Pierog, T.; Pieroni, P.; Pimenta, M.; Pirronello, V.; Platino, M.; Plum, M.; Revenu, B.; Ridky, J.; Riggi, S.; Risse, M.; Ristori, P.; Rivera, H.; Rizi, V.; Roberts, J.; Rodrigues de Carvalho, W.; Rodriguez, G.; Rouille-d'Orfeuil, B.; Roulet, E.; Rovero, A.C.; Ruhle, C.; Saftoiu, A.; Salamida, F.; Salazar, H.; Salesa Greus, F.; Salina, G.; Sanchez, F.; Santo, C.E.; Santos, E.; Santos, E.M.; Sarazin, F.; Sarkar, B.; Sarkar, S.; Sato, R.; Scharf, N.; Scherini, V.; Schieler, H.; Schiffer, P.; Schmidt, A.; Scholten, O.; Schoorlemmer, H.; Schovancova, J.; Schovanek, P.; Schroder, F.; Schuster, D.; Sciutto, S.J.; Scuderi, M.; Segreto, A.; Settimo, M.; Shadkam, A.; Shellard, R.C.; Sidelnik, I.; Sigl, G.; Silva Lopez, H.H.; Sima, O.; Smialkowski, A.; Smida, R.; Snow, G.R.; Sommers, P.; Sorokin, J.; Spinka, H.; Squartini, R.; Srivastava, Y.N.; Stanic, S.; Stapleton, J.; Stasielak, J.; Stephan, M.; Stutz, A.; Suarez, F.; Suomijarvi, T.; Supanitsky, A.D.; Susa, T.; Sutherland, M.S.; Swain, J.; Szadkowski, Z.; Szuba, M.; Tapia, A.; Tartare, M.; Tascau, O.; Tcaciuc, R.; Thao, N.T.; Thomas, D.; Tiffenberg, J.; Timmermans, C.; Tkaczyk, W.; Todero Peixoto, C.J.; Toma, G.; Tomankova, L.; Tome, B.; Tonachini, A.; Torralba Elipe, G.; Travnicek, P.; Tridapalli, D.B.; Tristram, G.; Trovato, E.; Tueros, M.; Ulrich, R.; Unger, M.; Urban, M.; Valdes Galicia, J.F.; Valino, I.; Valore, L.; van Aar, G.; van den Berg, A.M.; van Velzen, S.; van Vliet, A.; Varela, E.; Vargas Cardenas, B.; Vazquez, JR; Vazquez, R.A.; Veberic, D.; Verzi, V.; Vicha, J.; Videla, M.; Villasenor, L.; Wahlberg, H.; Wahrlich, P.; Wainberg, O.; Walz, D.; Watson, A.A.; Weber, M.; Weidenhaupt, K.; Weindl, A.; Werner, F.; Westerhoff, S.; Whelan, B.J.; Widom, A.; Wieczorek, G.; Wiencke, L.; Wilczynska, B.; Wilczynski, H.; Will, M.; Williams, C.; Winchen, T.; Wommer, M.; Wundheiler, B.; Yamamoto, T.; Yapici, T.; Younk, P.; Yuan, G.; Yushkov, A.; Zamorano Garcia, B.; Zas, E.; Zavrtanik, D.; Zavrtanik, M.; Zaw, I.; Zepeda, A.; Zhou, J.; Zhu, Y.; Zimbres Silva, M.; Ziolkowski, M.; Martin, L.

    2012-01-01

    The energy spectrum of ultra-high energy cosmic rays above 10(18)eV is measured using the hybrid events collected by the Pierre Auger Observatory between November 2005 and September 2010. The large exposure of the Observatory allows the measurement of the main features of the energy spectrum with hi

  20. Determination of neutron energy spectrum at KAMINI shielding experiment location.

    Science.gov (United States)

    Sen, Sujoy; Bagchi, Subhrojit; Prasad, R R; Venkatasubramanian, D; Mohanakrishnan, P; Keshavamurty, R S; Haridas, Adish; Arul, A John; Puthiyavinayagam, P

    2016-09-01

    The neutron spectrum at KAMINI reactor south beam tube end has been determined using multifoil activation method. This beam tube is being used for characterizing neutron attenuation of novel shield materials. Starting from a computed guess spectrum, the spectrum adjustment/unfolding procedure makes use of minimization of a modified constraint function representing (a) least squared deviations between the measured and calculated reaction rates, (b) a measure of sharp fluctuations in the adjusted spectrum and (c) the square of the deviation of adjusted spectrum from the guess spectrum. The adjusted/unfolded spectrum predicts the reaction rates accurately. The results of this new procedure are compared with those of widely used SAND-II code. PMID:27389881

  1. Analysis of large-scale anisotropy of ultra-high energy cosmic rays in HiRes data

    CERN Document Server

    Abbasi, R U; Allen, M; Amann, J F; Archbold, G; Belov, K; Belz, J W; Bergman, D R; Blake, S A; Brusova, O A; Burt, G W; Cannon, C; Cao, Z; Deng, W; Fedorova, Y; Findlay, J; Finley, C B; Gray, R C; Hanlon, W F; Hoffman, C M; Holzscheiter, M H; Hughes, G; Hüntemeyer, P; Ivanov, D; Jones, B F; Jui, C C H; Kim, K; Kirn, M A; Koers, H; Loh, E C; Maestas, M M; Manago, N; Marek, L J; Martens, K; Matthews, J A J; Matthews, J N; Moore, S A; O'Neill, A; Painter, C A; Perera, L; Reil, K; Riehle, R; Roberts, M D; Rodriguez, D; Sasaki, M; Schnetzer, S R; Scott, L M; Sinnis, G; Smith, J D; Sokolsky, P; Song, C; Springer, R W; Stokes, B T; Stratton, S R; Thomas, J R; Thomas, S B; Thomson, G B; Tinyakov, P; Tupa, D; Wiencke, L R; Zech, A; Zhang, X

    2010-01-01

    Stereo data collected by the HiRes experiment over a six year period are examined for large-scale anisotropy related to the inhomogeneous distribution of matter in the nearby Universe. We consider the generic case of small cosmic-ray deflections and a large number of sources tracing the matter distribution. In this matter tracer model the expected cosmic ray flux depends essentially on a single free parameter, the typical deflection angle theta. We find that the HiRes data with threshold energies of 40 EeV and 57 EeV are incompatible with the matter tracer model at a 95% confidence level unless theta is larger than 10 degrees and are compatible with an isotropic flux. The data set above 10 EeV is compatible with both the matter tracer model and an isotropic flux.

  2. Full Spectrum Diffused and Beamed Solar Energy Application Using Optical Fibre

    CERN Document Server

    Dutta Majumdar, M R

    2007-01-01

    Existing solar energy application systems use small fraction of full spectrum of solar energy. So attempts are made to show how full spectrum solar energy can be used for diffused and beamed form of incident solar energy. Luminescent Solar Concentrator (LSC) principle with optical fibre in diffused sun light and dielectric mirror separation technique with optical fibre in beamed form are discussed. Comparison of both the cases are done. Keywords: full spectrum, solar photonics, diffused solar energy, beamed solar energy, LSC, dielectric mirror, optical fibre, Photo-Voltaic

  3. Large-Scale Cosmic-Ray Anisotropy as a Probe of Interstellar Turbulence

    CERN Document Server

    Giacinti, Gwenael

    2016-01-01

    We calculate the large-scale cosmic-ray (CR) anisotropies predicted for a range of Goldreich-Sridhar (GS) and isotropic models of interstellar turbulence, and compare them with IceTop data. In general, the predicted CR anisotropy is not a pure dipole; the cold spots reported at 400 TeV and 2 PeV are consistent with a GS model that contains a smooth deficit of parallel-propagating waves and a broad resonance function, although some other possibilities cannot, as yet, be ruled out. In particular, isotropic fast magnetosonic wave turbulence can match the observations at high energy, but cannot accommodate an energy-dependence in the shape of the CR anisotropy. Our findings suggest that improved data on the large-scale CR anisotropy could provide a valuable probe of the properties - notably the power-spectrum - of the local interstellar turbulence.

  4. Time-resolved electron beam energy spectrum diagnostics for Vanderbilt FEL

    Science.gov (United States)

    Feng, Bibo; Kozub, John A.; Gabella, William E.

    2002-06-01

    A fast electron energy spectrometer has been built using a photodiode array measuring the backward optical transition radiation from a thin film of aluminum. The resolution of the electron energy spectrometer is about 0.2% with a time resolution of 50 ns. The maximum energy spread that can be measured is 6.4%. We present the measurements of the time-resolved electron beam energy spectrum on the Mark III linear accelerator at Vanderbilt University, while lasing at different wavelengths and while not lasing. We also discuss the effects of different parameters, such as cathode heating, alpha magnet strength and RF phase, on the electron energy spectrum and optical spectrum. The diagnostics of time-resolved electron energy spectrum and time-resolved laser spectrum provide the technology to understand the physical process of the FEL interaction. Based on these diagnostics, the FEL facility can realize some special modes of operation, such as macropulse chirping and macropulse two color lasing.

  5. Searches for Anisotropies in the Arrival Directions of the Highest Energy Cosmic Rays Detected by the Pierre Auger Observatory

    CERN Document Server

    ,

    2014-01-01

    We analyze the distribution of arrival directions of ultra-high energy cosmic rays recorded at the Pierre Auger Observatory in 10 years of operation. The data set, about three times larger than that used in earlier studies, includes arrival directions with zenith angles up to $80^\\circ$, thus covering from $-90^\\circ$ to $+45^\\circ$ in declination. After updating the fraction of events correlating with the active galactic nuclei (AGNs) in the V\\'eron-Cetty and V\\'eron catalog, we subject the arrival directions of the data with energies in excess of 40 EeV to different tests for anisotropy. We search for localized excess fluxes and for self-clustering of event directions at angular scales up to $30^\\circ$ and for different threshold energies between 40~EeV and 80~EeV. We then look for correlations of cosmic rays with celestial structures both in the Galaxy (the Galactic Center and Galactic Plane) and in the local Universe (the Super-Galactic Plane). We also examine their correlation with different populations ...

  6. Dynamic Behavior and Quasi-energy Spectrum of Multiband Superlattice Bloch Electrons in Quantum Kicked Potential

    Institute of Scientific and Technical Information of China (English)

    OUYANG BiYao; ZHAO XianGeng; CHEN ShiGang; LIU Jie

    2001-01-01

    In this paper, we study the dynamic behavior and quasi-energy spectrum of multiband superlattice Bloch electrons in quantum kicked potential. We show analytically and numerically the avoided crossing and band suppression about the quasi-energy spectrum, the dynamic nonlocalization, and the electron oscillation behavior between two bands.

  7. Measurement of the Energy Spectrum of Cosmic Rays with the Pierre Auger Observatory

    Science.gov (United States)

    Verzi, Valerio

    The energy spectrum of high-energy cosmic rays measured with the Pierre Auger Observatory is presented. The measurement is based on data collected until 31 December 2012 and extends over three orders of magnitude in energy from 3 × 1017 eV up to the very end of the spectrum. The spectral features are presented together with a detailed description of the recent improvements in determination of the energy scale.

  8. Segmentation-free x-ray energy spectrum estimation for computed tomography

    CERN Document Server

    Zhao, Wei; Niu, Tianye

    2016-01-01

    X-ray energy spectrum plays an essential role in imaging and related tasks. Due to the high photon flux of clinical CT scanners, most of the spectrum estimation methods are indirect and are usually suffered from various limitations. The recently proposed indirect transmission measurement-based method requires at least the segmentation of one material, which is insufficient for CT images of highly noisy and with artifacts. To combat for the bottleneck of spectrum estimation using segmented CT images, in this study, we develop a segmentation-free indirect transmission measurement based energy spectrum estimation method using dual-energy material decomposition. The general principle of the method is to compare polychromatic forward projection with raw projection to calibrate a set of unknown weights which are used to express the unknown spectrum together with a set of model spectra. After applying dual-energy material decomposition using high- and low-energy raw projection data, polychromatic forward projection ...

  9. Large-Angular Scales CMB Anisotropy from Excited Initial Mode

    CERN Document Server

    Sojasi, A; Yusofi, E

    2015-01-01

    According to the inflationary cosmology, the CMB anisotropy gives an opportunity to test predictions of the new physics hypothesis. Initial state of quantum fluctuations is one of the important options at high energy scale, which can affect on the observables such as CMB power spectrum. In this study a quasi-de Sitter inflationary background with approximate de Sitter mode function built over the Bunch-Davies mode is applied to investigate the scale-dependency of the CMB anisotropy. Indeed, considering the recent Planck constraint on spectral index, motivated us to examine the effect of new excited mode function (instead of pure de Sitter mode) on the CMB anisotropy in large-angular scales. In so doing, it was revealed that the angular scale-invariance in the CMB temperature fluctuations is broken and in the limit $ \\ell<200 $ the tiny deviation is appeared. Also, it was shown that the power spectrum of CMB anisotropy is dependent on the slow-roll parameter $\\epsilon $.

  10. Anisotropy of low energy direct photons in relativistic heavy ion collisions

    Science.gov (United States)

    Koide, T.; Kodama, T.

    2016-09-01

    Using the Wigner function approach for electromagnetic radiation fields, we investigate the behavior of low energy photons radiated by the deceleration processes of two colliding nuclei in relativistic heavy ion collisions. The angular distribution reveals information of the initial geometric configurations, which is reflected in the anisotropic parameter v 2, with an increasing v 2 as energy decreases. This behavior is qualitatively different to the v 2 from the hadrons produced in the collisions.

  11. Primordial anisotropies in gauged hybrid inflation

    International Nuclear Information System (INIS)

    We study primordial anisotropies generated in the model of gauged hybrid inflation in which the complex waterfall field is charged under a U(1)gauge field. Primordial anisotropies are generated either actively during inflation or from inhomogeneities modulating the surface of end of inflation during waterfall transition. We present a consistent δN mechanism to calculate the anisotropic power spectrum and bispectrum. We show that the primordial anisotropies generated at the surface of end of inflation do not depend on the number of e-folds and therefore do not produce dangerously large anisotropies associated with the IR modes. Furthermore, one can find the parameter space that the anisotropies generated from the surface of end of inflation cancel the anisotropies generated during inflation, therefore relaxing the constrains on model parameters imposed from IR anisotropies. We also show that the gauge field fluctuations induce a red-tilted power spectrum so the averaged power spectrum from the gauge field can change the total power spectrum from blue to red. Therefore, hybrid inflation, once gauged under a U(1) field, can be consistent with the cosmological observations

  12. Optimum thickness of soft magnetic phase in FePt/FeCo permanent magnet superlattices with high energy product and large magnetic anisotropy energy

    Directory of Open Access Journals (Sweden)

    Sandeep Kumar Jain

    2016-02-01

    Full Text Available Ab initio calculations on hard/soft (FePtm/(FeCon, (m = 4, 6, 8 and n = 2-2m magnetic superlattices show that the B2 type FeCo layers become anisotropic with varying interlayer spacing and enhanced magnetic moments. The average magnetic moment in superlattices is higher than in bulk FePt, resulting in high maximum energy product for (FePt4/(FeCo8 which is nearly double the calculated value for bulk FePt. The calculation of the magnetic anisotropy energy shows that the optimal thickness of the soft magnetic phase for good permanent magnet behaviour of the superlattice is less than ∼2 nm.

  13. Constraining the CDM spectrum normalization in flat dark energy cosmologies

    CERN Document Server

    Basilakos, S; Basilakos, Spyros

    2006-01-01

    We study the relation between the rms mass fluctuations on 8$h^{-1}$Mpc scales and $\\Omega_{\\rm m}$ using the recent clustering results of XMM-{\\it Newton} soft (0.5-2 keV) X-ray sources, which have a median redshift of $z\\sim 1.2$. The relation can be represented in the form $\\sigma_{8}=0.34 (\\pm 0.01) \\Omega_{\\rm m}^{-\\gamma}$ where $\\gamma\\equiv \\gamma(\\Omega_{\\rm m},w)$ and it is valid for all $w<-1/3$ models. By combining the X-ray clustering and SNIa data we find that the model which best reproduces the observational data is that with: $\\Omega_{\\rm m}\\simeq 0.26$, $w\\simeq -0.90$ and $\\sigma_{8}\\simeq 0.73$, which is in excellent agreement with the recent 3-year Wilkinson Microwave Anisotropy Probe results.

  14. Observation of Anisotropy in the Arrival Direction Distribution of TeV Cosmic Rays with HAWC

    CERN Document Server

    BenZvi, S Y; Westerhoff, S

    2015-01-01

    The High-Altitude Water Cherenkov (HAWC) Observatory, located 4100 m above sea level near Sierra Negra (19$^\\circ$ N) in Mexico, is sensitive to gamma rays and cosmic rays at TeV energies. The arrival direction distribution of cosmic rays at these energies shows significant anisotropy on several angular scales, with a relative intensity ranging between 10$^{-3}$ and 10$^{-4}$. We present the results of a study of cosmic-ray anisotropy based on more than 86 billion cosmic-ray air showers recorded with HAWC since June 2013. The HAWC cosmic-ray sky map, which has a median energy of 2 TeV, exhibits several regions of significantly enhanced cosmic-ray flux. We present the energy dependence of the anisotropy and the cosmic-ray spectrum in the regions of significant excess.

  15. Ab initio and work function and surface energy anisotropy of LaB6

    NARCIS (Netherlands)

    Uijttewaal, M. A.; de Wijs, G. A.; de Groot, R. A.

    2006-01-01

    Lanthanum hexaboride is one of the cathode materials most used in high-power electronics technology, but the many experimental results do not provide a consistent picture of the surface properties. Therefore, we report the first ab initio calculations of the work functions and surface energies of th

  16. A Modified Energy Detection Based Spectrum Sensing Algorithm for Green Cognitive Radio Communication

    Directory of Open Access Journals (Sweden)

    Sidra Rajput

    2015-10-01

    Full Text Available Spectrum Sensing is the first and fundamental function of Cognitive Cycle which plays a vital role in the success of CRs (Cognitive Radios. Spectrum Sensing indicate the presence and absence of PUs (Primary Users in RF (Radio Frequency spectrum occupancy measurements. In order to correctly determine the presence and absence of Primary Users, the algorithms in practice include complex mathematics which increases the computational complexity of the algorithm, thus shifted the CRs to operate as ?green? communication systems. In this paper, an energy efficient and computationally less complex, energy detection based Spectrum Sensing algorithm have been proposed. The design goals of the proposed algorithm are to save the processing and sensing energies. At first, by using less MAC (Multiply and Accumulate operation, it saves the processing energy needed to determine the presence and absence of PUs. Secondly, it saves the sensing energy by providing a way to find lowest possible sensing time at which spectrum is to be sensed. Two scenarios have been defined for testing the proposed algorithm i.e. simulate detection capability of Primary Users in ideal and noisy scenarios. Detection of PUs in both of these scenarios have been compared to obtain the probability of detection. Energy Efficiency of the proposed algorithm has been proved by making performance comparison between the proposed (less complex algorithm and the legacy energy detection algorithm. With reduced complexity, the proposed spectrum sensing algorithm can be considered under the paradigm of Green Cognitive Radio Communication

  17. A modified energy detection based spectrum sensing algorithm for green cognitive radio communication

    International Nuclear Information System (INIS)

    Spectrum Sensing is the first and fundamental function of Cognitive Cycle which plays a vital role in the success of CRs (Cognitive Radios). Spectrum Sensing indicate the presence and absence of PUs (Primary Users) in RF (Radio Frequency) spectrum occupancy measurements. In order to correctly determine the presence and absence of Primary Users, the algorithms in practice include complex mathematics which increases the computational complexity of the algorithm, thus shifted the CRs to operate as ?green? communication systems. In this paper, an energy efficient and computationally less complex, energy detection based Spectrum Sensing algorithm have been proposed. The design goals of the proposed algorithm are to save the processing and sensing energies. At first, by using less MAC (Multiply and Accumulate) operation, it saves the processing energy needed to determine the presence and absence of PUs. Secondly, it saves the sensing energy by providing a way to find lowest possible sensing time at which spectrum is to be sensed. Two scenarios have been defined for testing the proposed algorithm i.e. simulate detection capability of Primary Users in ideal and noisy scenarios. Detection of PUs in both of these scenarios have been compared to obtain the probability of detection. Energy Efficiency of the proposed algorithm has been proved by making performance comparison between the proposed (less complex) algorithm and the legacy energy detection algorithm. With reduced complexity, the proposed spectrum sensing algorithm can be considered under the paradigm of Green Cognitive Radio Communication. (author)

  18. The Cosmic Ray Energy Spectrum Observed with the Surface Detector of the Telescope Array Experiment

    OpenAIRE

    Abu-Zayyad, T.; Aida, R.; Allen, M.; Anderson, R; Azuma, R.; Barcikowski, E.; Belz, J. W.; Bergman, D. R.; Blake, S. A.; Cady, R.; B.G. Cheon; Chiba, J.; Chikawa, M.; Cho, E. J.; Cho, W. R.

    2012-01-01

    The Telescope Array (TA) collaboration has measured the energy spectrum of ultra-high energy cosmic rays with primary energies above 1.6 x 10^(18) eV. This measurement is based upon four years of observation by the surface detector component of TA. The spectrum shows a dip at an energy of 4.6 x 10^(18) eV and a steepening at 5.4 x 10^(19) eV which is consistent with the expectation from the GZK cutoff. We present the results of a technique, new to the analysis of ultra-high energy cosmic ray ...

  19. Energy spectrum analysis of blast waves based on an improved Hilbert-Huang transform

    Science.gov (United States)

    Li, L.; Wang, F.; Shang, F.; Jia, Y.; Zhao, C.; Kong, D.

    2016-07-01

    Using the improved Hilbert-Huang transform (HHT), this paper investigates the problems of analysis and interpretation of the energy spectrum of a blast wave. It has been previously established that the energy spectrum is an effective feature by which to characterize a blast wave. In fact, the higher the energy spectra in a frequency band of a blast wave, the greater the damage to a target in the same frequency band. However, most current research focuses on analyzing wave signals in the time domain or frequency domain rather than considering the energy spectrum. We propose here an improved HHT method combined with a wavelet packet to extract the energy spectrum feature of a blast wave. When applying the HHT, the signal is first roughly decomposed into a series of intrinsic mode functions (IMFs) by empirical mode decomposition. The wavelet packet method is then performed on each IMF to eliminate noise on the energy spectrum. Second, a coefficient is introduced to remove unrelated IMFs. The energy of each instantaneous frequency can be derived through the Hilbert transform. The energy spectrum can then be obtained by adding up all the components after the wavelet packet filters and screens them through a coefficient to obtain the effective IMFs. The effectiveness of the proposed method is demonstrated by 12 groups of experimental data, and an energy attenuation model is established based on the experimental data. The improved HHT is a precise method for blast wave signal analysis. For other shock wave signals from blasting experiments, an energy frequency time distribution and energy spectrum can also be obtained through this method, allowing for more practical applications.

  20. Revisiting the hardening of the cosmic-ray energy spectrum at TeV energies

    CERN Document Server

    Thoudam, Satyendra

    2013-01-01

    Measurements of cosmic rays by experiments such as ATIC, CREAM, and PAMELA indicate a hardening of the cosmic-ray energy spectrum at TeV energies. In our recent work (Thoudam & H\\"orandel 2012a), we showed that the hardening can be due to the effect of nearby supernova remnants. We showed it for the case of proton and helium. In this paper, we present an improved and detailed version of our previous work, and extend our study to heavier cosmic-ray species such as boron, carbon, oxygen, and iron nuclei. Unlike our previous study, the present work involves a detailed calculation of the background cosmic rays and follows a consistent treatment of cosmic-ray source parameters between the background and the nearby components. Moreover, we also present a detailed comparison of our results on the secondary-to-primary ratios, secondary spectra, and the diffuse gamma-ray spectrum with the results expected from other existing models, which can be checked by future measurements at high energies.

  1. Phenomenological Rashba model for calculating the electron energy spectrum on a cylinder

    Science.gov (United States)

    Savinskiĭ, S. S.; Belosludtsev, A. V.

    2007-05-01

    The energy spectrum of an electron on the surface of a cylinder is calculated using the Pauli equation with an additional term that takes into account the spin-orbit interaction. This term is taken in the approximation of a phenomenological Rashba model, which provides exact expressions for the wave functions and the electron energy spectrum on the cylinder surface in a static magnetic field.

  2. Application of wavelet packet decomposition and its energy spectrum on the coal-rock interface identification

    Institute of Scientific and Technical Information of China (English)

    任芳; 杨兆建; 熊诗波; 梁义维

    2003-01-01

    The theory and method of wavelet packet decomposition and its energy spectrum dealing with the coal-rock Interface Identification are presented in the paper. The characteristic frequency band of the coal-rock signal could be identified by wavelet packet decomposition and its energy spectrum conveniently, at the same time, quantification analysis were performed. The result demonstrates that this method is more advantageous and of practical value than traditional Fourier analysis method.

  3. Development of unfolding energy spectrum with clinical linear accelerator based on transmission data

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Hyun Joon; Park Hyo Jun; Yoo, Do Hyeon; Min, Chul Hee [Dept. of Radiation Convergence Engineering, Yonsei University, Seoul (Korea, Republic of); Kim, Byoung Chul; Yi, Chul Young [Center for Ionizing Radiation, Korea Research Institute of Standards and Science, Daejeon (Korea, Republic of)

    2016-05-15

    For the accurate dose assessment in radiation therapy, energy spectrum of the photon beam generated from the linac head is essential. The aim of this study is to develop the technique to accurately unfolding the energy spectrum with the transmission analysis method. Clinical linear accelerator and Monet Carlo method was employed to evaluate the transmission signals according to the thickness of the observer material, and then the response function of the ion chamber response was determined with the mono energy beam. Finally the energy spectrum was unfolded with HEPROW program. Elekta Synergy Flatform and Geant4 tool kits was used in this study. In the comparison between calculated and measured transmission signals using aluminum alloy as an attenuator, root mean squared error was 0.43%. In the comparison between unfolded spectrum using HEPROW program and calculated spectrum using Geant4, the difference of peak and mean energy were 0.066 and 0.03 MeV, respectively. However, for the accurate prediction of the energy spectrum, additional experiment with various type of material and improvement of the unfolding program is required. In this research, it is demonstrated that unfolding spectra technique could be used in megavoltage photon beam with aluminum alloy and HEPROW program.

  4. Spectrum and Composition of Ultra-high Energy Cosmic Rays from Semi-relativistic Hypernovae

    OpenAIRE

    Liu, Ruo-Yu; Wang, Xiang-Yu

    2011-01-01

    It has been suggested that hypernova remnants, with a substantial amount of energy in semi-relativistic ejecta, can accelerate intermediate mass or heavy nuclei to ultra-high energies and provide sufficient amount of energy in cosmic rays to account for the observed flux. We here calculate the expected energy spectrum and chemical composition of ultra-high energy cosmic rays from such semi-relativistic hypernovae. With a chemical composition equal to that of the hypernova ejecta and a flat or...

  5. Anisotropy of the critical current in MgB2 tapes made of high energy milled precursor powder

    DEFF Research Database (Denmark)

    Hässler, W.; Kovac, P.; Eisterer, M.;

    2010-01-01

    For applications of MgB2 wires or tapes, high critical currents in high magnetic fields are essential. By using tapes in superconducting coils the anisotropic behaviour of the critical current, i.e. the dependence on the direction of the external field in relation to the tape surface, has...... to be taken into account. The anisotropy of MgB2 tapes with mechanically alloyed (MA) precursor powder and different sheath materials which can be much higher than the intrinsic anisotropy is discussed. Furthermore tapes with pure and C doped MA-MgB2 precursor are compared. Tapes with a hard Fe......-sheath and undoped precursor show a high extrinsic anisotropy of the critical current density which can be reduced considerably by carbon doping. A texture of the MgB2 phase in the tape filaments introduced by flat rolling was observed by synchrotron x-ray diffraction. Using this texture information the observed...

  6. Spectrum and Composition of Ultra-high Energy Cosmic Rays from Semi-relativistic Hypernovae

    CERN Document Server

    Liu, Ruo-Yu

    2011-01-01

    It has been suggested that hypernova remnants, with a substantial amount of energy in semi-relativistic ejecta, can accelerate intermediate mass or heavy nuclei to ultra-high energies and provide sufficient amount of energy in cosmic rays to account for the observed flux. We here calculate the expected energy spectrum and chemical composition of ultra-high energy cosmic rays from such semi-relativistic hypernovae. With a chemical composition equal to that of the hypernova ejecta and a flat or hard spectrum for cosmic rays at the sources, the spectrum and composition of the propagated cosmic rays observed at the Earth can be compatible with the measurements by the Pierre Auger Observatory.

  7. Influence of the Richtmyer-Meshkov instability on the kinetic energy spectrum.

    Energy Technology Data Exchange (ETDEWEB)

    Weber, Christopher R. (University of Wisconsin-Madison, Madison, WI)

    2010-09-01

    The fluctuating kinetic energy spectrum in the region near the Richtmyer-Meshkov instability (RMI) is experimentally investigated using particle image velocimetry (PIV). The velocity field is measured at a high spatial resolution in the light gas to observe the effects of turbulence production and dissipation. It is found that the RMI acts as a source of turbulence production near the unstable interface, where energy is transferred from the scales of the perturbation to smaller scales until dissipation. The interface also has an effect on the kinetic energy spectrum farther away by means of the distorted reflected shock wave. The energy spectrum far from the interface initially has a higher energy content than that of similar experiments with a flat interface. These differences are quick to disappear as dissipation dominates the flow far from the interface.

  8. Studies of velocity fluctuations in the lower atmosphere using the MU radar. I - Azimuthal anisotropy. II - Momentum fluxes and energy densities

    Science.gov (United States)

    Vanzandt, T. E.; Smith, S. A.; Tsuda, T.; Sato, T.; Fritts, D. C.

    1990-01-01

    Results are presented from a six-day campaign to observe velocity fluctuations in the lower atmosphere using the MU radar (Fukao et al., 1985) in Shigaraki, Japan in March, 1986. Consideration is given to the azimuthal anisotropy, the frequency spectra, the vertical profiles of energy density, and the momentum flux of the motion field. It is found that all of the observed azimuthal variations are probably caused by a gravity wave field whose parameters vary with time. The results show significant differences between the mean zonal and meridional frequency spectra and different profiles of mean energy density with height for different frequency bands and for zonal and meridional components.

  9. [Application of the racial algorithm in energy dispersive X-ray fluorescence overlapped spectrum analysis].

    Science.gov (United States)

    Zeng, Guo-Qiang; Luo, Yao-Yao; Ge, Liang-Quan; Zhang, Qing-Xian; Gu, Yi; Cheng, Feng

    2014-02-01

    In the energy dispersive X-ray fluorescence spectrum analysis, scintillation detector such as NaI (Tl) detector usually has a low energy resolution at around 8%. The low energy resolution causes problems in spectral data analysis especially in the high background and low counts condition, it is very limited to strip the overlapped spectrum, and the more overlapping the peaks are, the more difficult to peel the peaks, and the qualitative and quantitative analysis can't be carried out because we can't recognize the peak address and peak area. Based on genetic algorithm and immune algorithm, we build a new racial algorithm which uses the Euclidean distance as the judgment of evolution, the maximum relative error as the iterative criterion to be put into overlapped spectrum analysis, then we use the Gaussian function to simulate different overlapping degrees of the spectrum, and the racial algorithm is used in overlapped peak separation and full spectrum simulation, the peak address deviation is in +/- 3 channels, the peak area deviation is no more than 5%, and it is proven that this method has a good effect in energy dispersive X-ray fluorescence overlapped spectrum analysis.

  10. Anisotropy in solar wind plasma turbulence.

    Science.gov (United States)

    Oughton, S; Matthaeus, W H; Wan, M; Osman, K T

    2015-05-13

    A review of spectral anisotropy and variance anisotropy for solar wind fluctuations is given, with the discussion covering inertial range and dissipation range scales. For the inertial range, theory, simulations and observations are more or less in accord, in that fluctuation energy is found to be primarily in modes with quasi-perpendicular wavevectors (relative to a suitably defined mean magnetic field), and also that most of the fluctuation energy is in the vector components transverse to the mean field. Energy transfer in the parallel direction and the energy levels in the parallel components are both relatively weak. In the dissipation range, observations indicate that variance anisotropy tends to decrease towards isotropic levels as the electron gyroradius is approached; spectral anisotropy results are mixed. Evidence for and against wave interpretations and turbulence interpretations of these features will be discussed. We also present new simulation results concerning evolution of variance anisotropy for different classes of initial conditions, each with typical background solar wind parameters.

  11. The spectrum of high-energy cosmic rays measured with KASCADE-Grande

    CERN Document Server

    Apel, W D; Bekk, K; Bertaina, M; Bluemer, J; Bozdog, H; Brancus, I M; Buchholz, P; Cantoni, E; Chiavassa, A; Cossavella, F; Daumiller, K; de Souza, V; Di Pierro, F; Doll, P; Engel, R; Engler, J; Finger, M; Fuhrmann, D; Ghia, P L; Gils, H J; Glasstetter, R; Grupen, C; Haungs, A; Heck, D; Hoerandel, J R; Huber, D; Huege, T; Kampert, K -H; Kang, D; Kickelbick, D; Klages, H O; Link, K; Luczak, P; Ludwig, M; Mathes, H J; Mayer, H J; Melissas, M; Milke, J; Mitrica, B; Morello, C; Navarra, G; Oehlschlaeger, J; Ostapchenko, S; Over, S; Palmieri, N; Petcu, M; Pierog, T; Rebel, H; Roth, M; Schieler, H; Schroeder, F G; Sima, O; Toma, G; Trinchero, G C; Ulrich, H; Weindl, A; Wochele, J; Wommer, M; Zabierowski, J

    2012-01-01

    The energy spectrum of cosmic rays between 10**16 eV and 10**18 eV, derived from measurements of the shower size (total number of charged particles) and the total muon number of extensive air showers by the KASCADE-Grande experiment, is described. The resulting all-particle energy spectrum exhibits strong hints for a hardening of the spectrum at approximately 2x10**16 eV and a significant steepening at c. 8x10**16 eV. These observations challenge the view that the spectrum is a single power law between knee and ankle. Possible scenarios generating such features are discussed in terms of astrophysical processes that may explain the transition region from galactic to extragalactic origin of cosmic rays.

  12. Neutron energy flux spectrum measurements for leu core of PARR-1

    Energy Technology Data Exchange (ETDEWEB)

    Iqbal, M.; Ayazudin, S.K.; Pervez, S.

    1995-01-01

    The Pakistan Research Reactor-1 has been converted and upgraded from highly enriched uranium (HEU) to low enriched uranium (LEU) fuel from 5 to 9MW. An experimental programme was undertaken to measure the neutron energy spectra in the core and at the irradiated and activity of the foils was measured using high efficiency HPGe gamma ray spectroscopy system. The measured saturation activities were used in the spectrum adjustment computer code SANDBP. A sample energy spectrum for the material test reactor supplied by the International Atomic Energy Agency (IAEA) was used as the input to the SANDBP code, and the final spectra were obtained by iterative adjustment.

  13. Material grain size characterization method based on energy attenuation coefficient spectrum and support vector regression.

    Science.gov (United States)

    Li, Min; Zhou, Tong; Song, Yanan

    2016-07-01

    A grain size characterization method based on energy attenuation coefficient spectrum and support vector regression (SVR) is proposed. First, the spectra of the first and second back-wall echoes are cut into several frequency bands to calculate the energy attenuation coefficient spectrum. Second, the frequency band that is sensitive to grain size variation is determined. Finally, a statistical model between the energy attenuation coefficient in the sensitive frequency band and average grain size is established through SVR. Experimental verification is conducted on austenitic stainless steel. The average relative error of the predicted grain size is 5.65%, which is better than that of conventional methods.

  14. Primary electron spectrometer, 18:63 UE: Electrostatic analyzer description and energy spectrum determination

    Science.gov (United States)

    Pongratz, M. B.

    1973-01-01

    The primary electron spectrometer used to detect auroral electrons on sounding rocket 18:63 UE is described. The spectrometer used exponentially decaying positive and negative voltages applied to spherical deflection plates for energy analysis. A method for determining the analyzer response which does not require the assumptions that the ratio of plate separation to mean radius, the entrance or the exit apertures are small is described. By comparison with experiment it is shown that the effect of neither entrance nor exit collimation can be ignored. The experimental and calculated values of the limiting orbits agree well. A non-iterative technique of unfolding the electron differential energy spectrum is described. This method does not require the usual assumption of a flat or histogram-type energy spectrum. The unfolded spectra using both this technique and one which assumes a flat spectrum are compared to actual input spectra. This technique is especially useful in analyzing peaked auroral electron energy spectra.

  15. Backscatter, anisotropy, and polarization of solar hard X-rays

    Science.gov (United States)

    Bai, T.; Ramaty, R.

    1978-01-01

    The problems of anisotropy, polarization, center-to-limb variation of the X-ray spectrum, and Compton backscatter are investigated in a study of solar hard X-rays. Effect of backscatter are found particularly important for anisotropic sources which emit hard X-rays predominantly toward the photosphere; for such anisotropic primary X-ray sources, the observed X-ray flux near 30 keV does not depend significantly on the position of the flare. In addition, the degree of polarization of the sum of the primary and reflected X-rays with energies in the 15 to 30 keV range may be as high as 30%. Determination of the height and anisotropy of the primary X-ray sources from study of the albedo patch is also discussed.

  16. The invariance of current energy fourier spectrum of discrete real signals on finite intervals

    Directory of Open Access Journals (Sweden)

    Ponomarev V. A.

    2014-02-01

    Full Text Available Digital spectral analysis of signals based on DFT has a number of advantages. However, the transition from analog to digital methods and techniques is accompanied by a number of undesirable effects. Signals in each subject area usually have their own specifics. Therefore, it is necessary to study these effects in applications of spectral Fourier analysis. Such research is important for three reasons. Firstly, DFT properties are accurate, have their own specificity and significantly differ from the properties of the Fourier transform of continuous signals. Secondly, signals in each subject area have their own specificity. Thirdly, researchers often have prevailing knowledge in some particular domain, rather than in the field of digital signal processing techniques. As a result, in practice, some of the processes and effects arising in applications of digital spectral analysis, unfortunately, escape the attention of researchers which can result in erroneous conclusions. The paper deals with the problems of measuring Fourier spectrum of signals in the base of discrete exponential functions. Methods and algorithms of sliding measurements of energy Fourier spectrum of signals on finite intervals were described. The invariance of current energy Fourier spectrum to moving discrete real signals (which are not periodic were investigated. The authors identify a new effect of digital spectral analysis — the effect of non-invariance of the current energy Fourier spectrum. Theoretical and practical results of analysis of invariance of current energy Fourier spectrum of tonal components are shown. The conducted studies allow us: — to see in a new light the measurement results on finite intervals of current Fourier spectrum and the current energy Fourier spectra of signals; give a numerical estimate of the non-invariance of the current energy Fourier spectrum of real tonal components. — to increase the effectiveness of digital spectral analysis in its

  17. A depression before a bump in the highest energy cosmic ray spectrum

    OpenAIRE

    Anchordoqui, L. A.; Dova, M. T.; Epele, L. N.; Swain, J. D.

    1997-01-01

    We re-examine the interaction of ultra high energy nuclei with the microwave background radiation. We find that the giant dipole resonance leaves a new signature in the differential energy spectrum of iron sources located around 3 Mpc: A depression before the bump which is followed by the expected cutoff.

  18. Improving the Accuracy of the Neutron Energy Spectrum Estimation in Electronuclear Installations under Study

    CERN Document Server

    Barashenkov, V S; Soloviev, A G; Sosnin, A N

    2000-01-01

    A time-saving method to build distributions which requires significantly lower volumes of the data samples than building a histogram is proposed. Effectivenes of the method is shown taking an example of the energy spectrum of the neutron source (E < 10.5 MeV) generated in the large uranium block irradiated with high energy protons.

  19. The energy-momentum spectrum in local field theories with broken Lorentz-symmetry

    International Nuclear Information System (INIS)

    Assuming locality of the observables and positivity of the energy it is shown that the joint spectrum of the energy-momentum operators has a Lorentz-invariant lower boundary in all superselection sectors. This result is of interest if the Lorentz-symmetry is (spontaneously) broken, such as in the charged sectors of quantum electrodynamics. (orig.)

  20. Corrections on energy spectrum and scatterings for fast neutron radiography at NECTAR facility

    OpenAIRE

    Shu-Quan, Liu; Thomas, Bücherl; Hang, Li; Yu-Bin, Zou; Yuan-Rong, Lu; Zhi-Yu, Guo

    2013-01-01

    Neutron spectrum and scattered neutrons caused distortions are major problems in fast neutron radiography and should be considered for improving the image quality. This paper puts emphasis on the removal of these image distortions and deviations for fast neutron radiography performed at the NECTAR facility of the research reactor FRM-II in Technische Universit\\"at M\\"unchen (TUM), Germany. The NECTAR energy spectrum is analyzed and established to modify the influence caused by neutron spectru...

  1. Search for radiative decays of cosmic background neutrino using cosmic infrared background energy spectrum

    International Nuclear Information System (INIS)

    We propose to search for the neutrino radiative decay by fitting a photon energy spectrum of the cosmic infrared background to a sum of the photon energy spectrum from the neutrino radiative decay and a continuum. By comparing the present cosmic infrared background energy spectrum observed by AKARI and Spitzer to the photon energy spectrum expected from neutrino radiative decay with a maximum likelihood method, we obtained a lifetime lower limit of 3.1x1012 to 3.8x1012 years at 95% confidence level for the third generation neutrino v3 in the v3 mass range between 50 and 150 meV/c2 under the present constraints by the neutrino oscillation measurements. In the left-right symmetric model, the minimum lifetime of v3 is predicted to be 1.5x1017 years for m3 of 50 meV/c2. We studied the feasibility of the observation of the neutrino radiative decay with a lifetime of 1.5x1017 years, by measuring a continuous energy spectrum of the cosmic infrared background. (author)

  2. Energy Spectrum of Ultra-High Energy Cosmic Rays Observed with the Telescope Array Using a Hybrid Technique

    CERN Document Server

    Abu-Zayyad, T; Allen, M; Anderson, R; Azuma, R; Barcikowski, E; Belz, J W; Bergman, D R; Blake, S A; Cady, R; Cheon, B G; Chiba, J; Chikawa, M; Cho, E J; Cho, W R; Fujii, H; Fujii, T; Fukuda, T; Fukushima, M; Hanlon, W; Hayashi, K; Hayashi, Y; Hayashida, N; Hibino, K; Hiyama, K; Honda, K; Iguchi, T; Ikeda, D; Ikuta, K; Inoue, N; Ishii, T; Ishimori, R; Ito, H; Ivanov, D; Iwamoto, S; Jui, C C H; Kadota, K; Kakimoto, F; Kalashev, O; Kanbe, T; Kasahara, K; Kawai, H; Kawakami, S; Kawana, S; Kido, E; Kim, H B; Kim, H K; Kim, J H; Kitamoto, K; Kitamura, S; Kitamura, Y; Kobayashi, K; Kobayashi, Y; Kondo, Y; Kuramoto, K; Kuzmin, V; Kwon, Y J; Lan, J; Lim, S I; Lundquist, J P; Machida, S; Martens, K; Matsuda, T; Matsuura, T; Matsuyama, T; Matthews, J N; Minamino, M; Miyata, K; Murano, Y; Myers, I; Nagasawa, K; Nagataki, S; Nakamura, T; Nam, S W; Nonaka, T; Ogio, S; Ohnishi, M; Ohoka, H; Oki, K; Oku, D; Okuda, T; Ono, M; Oshima, A; Ozawa, S; Park, I H; Pshirkov, M S; Rodriguez, D C; Roh, S Y; Rubtsov, G; Ryu, D; Sagawa, H; Sakurai, N; Sampson, A L; Scott, L M; Shah, P D; Shibata, F; Shibata, T; Shimodaira, H; Shin, B K; Shin, J I; Shirahama, T; Smith, J D; Sokolsky, P; Springer, R W; Stokes, B T; Stratton, S R; Stroman, T; Suzuki, S; Takahashi, Y; Takeda, M; Taketa, A; Takita, M; Tameda, Y; Tanaka, H; Tanaka, K; Tanaka, M; Thomas, S B; Thomson, G B; Tinyakov, P; Tkachev, I; Tokuno, H; Tomida, T; Troitsky, S; Tsunesada, Y; Tsutsumi, K; Tsuyuguchi, Y; Uchihori, Y; Udo, S; Ukai, H; Urban, F; Vasiloff, G; Wada, Y; Wong, T; Yamakawa, Y; Yamane, R; Yamaoka, H; Yamazaki, K; Yang, J; Yoneda, Y; Yoshida, S; Yoshii, H; Zhou, X; Zollinger, R; Zundel, Z

    2013-01-01

    We measure the spectrum of cosmic rays with energies greater than $10^{18.2}$ eV with the Fluorescence Detectors (FDs) and the Surface Detectors (SDs) of the Telescope Array Experiment using the data taken in our first 2.3-year observation from May 27 2008 to September 7 2010. A hybrid air shower reconstruction technique is employed to improve accuracies in determination of arrival directions and primary energies of cosmic rays using both FD and SD data. The energy spectrum presented here is in agreement with our previously published spectra and the HiRes results.

  3. Energy Spectrum of Ultra-High Energy Cosmic Rays Observed with the Telescope Array Using a Hybrid Technique

    OpenAIRE

    Abu-Zayyad, T.; Aida, R.; Allen, M.; Anderson, R; Azuma, R.; Barcikowski, E.; Belz, J. W.; Bergman, D. R.; Blake, S. A.; Cady, R.; B.G. Cheon; Chiba, J.; Chikawa, M.; Cho, E. J.; Cho, W. R.

    2013-01-01

    We measure the spectrum of cosmic rays with energies greater than $10^{18.2}$ eV with the Fluorescence Detectors (FDs) and the Surface Detectors (SDs) of the Telescope Array Experiment using the data taken in our first 2.3-year observation from May 27 2008 to September 7 2010. A hybrid air shower reconstruction technique is employed to improve accuracies in determination of arrival directions and primary energies of cosmic rays using both FD and SD data. The energy spectrum presented here is ...

  4. Energy spectrum of argon ions emitted from Filippov type Sahand plasma focus

    Energy Technology Data Exchange (ETDEWEB)

    Mohammadnejad, M.; Pestehe, S. J.; Mohammadi, M. A. [Department of Atomic and Molecular Physics, Faculty of Physics, University of Tabriz, Postal Code 5166614766, Tabriz (Iran, Islamic Republic of); Research Institute for Applied Physics and Astronomy, University of Tabriz, Tabriz (Iran, Islamic Republic of)

    2013-07-15

    The energy and flux of the argon ions produced in Sahand plasma focus have been measured by employing a well-designed Faraday cup. The secondary electron emission effects on the ion signals are simulated and the dimensions of Faraday cup are optimized to minimize these effects. The measured ion energy spectrum is corrected for the ion energy loss and charge exchange in the background gas. The effects of the capacitor bank voltage and working gas pressure on the ion energy spectrum are also investigated. It has been shown that the emitted ion number per energy increases as the capacitor bank voltage increases. Decreasing the working gas pressure leads to the increase in the number of emitted ion per energy.

  5. Neutron energy spectrum adjustment using deposited metal films on Teflon in the miniature neutron source reactor.

    Science.gov (United States)

    Nassan, L; Abdallah, B; Omar, H; Sarheel, A; Alsomel, N; Ghazi, N

    2016-01-01

    The focus of this article was on the experimental estimation of the neutron energy spectrum in the inner irradiation site of the miniature neutron source reactor (MNSR), using, for the first time, a selected set of deposited metal films on Teflon (DMFTs) neutron detectors. Gold, copper, zinc, titanium, aluminum, nickel, silver, and chromium were selected because of the dependence of their neutron cross-sections on neutron energy. Emphasis was placed on the usability of this new type of neutron detectors in the total neutron energy spectrum adjustment. The measured saturation activities per target nucleus values of the DMFTs, and the calculated neutron spectrum in the inner irradiation site using the MCNP-4C code were used as an input for the STAY'SL computer code during the adjustment procedure. The agreement between the numerically calculated and experimentally adjusted spectra results was discussed. PMID:26562448

  6. Correlation of D-D neutron yield and D/sup +/ energy spectrum in focused discharges

    International Nuclear Information System (INIS)

    The energy spectrum N(E) of the D/sup +/ ion emission from ≅ 0.6 MA focused discharges is determined with Thomson spectrometers for different conditions (D/sub 2/ filling pressure, capacitor bank voltage, and geometry of field distortion elements in the interelectrode gap). Linear correlation coefficients c/sub i/ for a characteristic element of the spectrum (e.g. the spectrum amplitude within a selected energy interval E, E+ΔE) and the neutron yield n is determined for a large number of discharges. The interplay of two leading processes in the neutron production, ion acceleration and ion trapping in the self magnetic field of the pinch, is analyzed in terms of correlation coefficients c/sub i/ and peak neutron energy

  7. The effect of the geomagnetic field on cosmic ray energy estimates and large scale anisotropy searches on data from the Pierre Auger Observatory

    CERN Document Server

    Abreu, P; Ahn, E J; Albuquerque, I F M; Allard, D; Allekotte, I; Allen, J; Allison, P; Castillo, J Alvarez; Alvarez-Muñiz, J; Ambrosio, M; Aminaei, A; Anchordoqui, L; Andringa, S; Antičić, T; Anzalone, A; Aramo, C; Arganda, E; Arqueros, F; Asorey, H; Assis, P; Aublin, J; Ave, M; Avenier, M; Avila, G; Bäcker, T; Balzer, M; Barber, K B; Barbosa, A F; Bardenet, R; Barroso, S L C; Baughman, B; Bäuml, J; Beatty, J J; Becker, B R; Becker, K H; Bellétoile, A; Bellido, J A; BenZvi, S; Berat, C; Bertou, X; Biermann, P L; Billoir, P; Blanco, F; Blanco, M; Bleve, C; Blümer, H; Boháčová, M; Boncioli, D; Bonifazi, C; Bonino, R; Borodai, N; Brack, J; Brogueira, P; Brown, W C; Bruijn, R; Buchholz, P; Bueno, A; Burton, R E; Caballero-Mora, K S; Caramete, L; Caruso, R; Castellina, A; Catalano, O; Cataldi, G; Cazon, L; Cester, R; Chauvin, J; Cheng, S H; Chiavassa, A; Chinellato, J A; Chou, A; Chudoba, J; Clay, R W; Coluccia, M R; Conceição, R; Contreras, F; Cook, H; Cooper, M J; Coppens, J; Cordier, A; Coutu, S; Covault, C E; Creusot, A; Criss, A; Cronin, J; Curutiu, A; Dagoret-Campagne, S; Dallier, R; Dasso, S; Daumiller, K; Dawson, B R; de Almeida, R M; De Domenico, M; De Donato, C; de Jong, S J; De La Vega, G; Junior, W J M de Mello; Neto, J R T de Mello; De Mitri, I; de Souza, V; de Vries, K D; Decerprit, G; del Peral, L; del Río, M; Deligny, O; Dembinski, H; Dhital, N; Di Giulio, C; Diaz, J C; Castro, M L Díaz; Diep, P N; Dobrigkeit, C; Docters, W; D'Olivo, J C; Dong, P N; Dorofeev, A; Anjos, J C dos; Dova, M T; D'Urso, D; Dutan, I; Ebr, J; Engel, R; Erdmann, M; Escobar, C O; Espadanal, J; Etchegoyen, A; Luis, P Facal San; Tapia, I Fajardo; Falcke, H; Farrar, G; Fauth, A C; Fazzini, N; Ferguson, A P; Ferrero, A; Fick, B; Filevich, A; Filipčič, A; Fliescher, S; Fracchiolla, C E; Fraenkel, E D; Fröhlich, U; Fuchs, B; Gaior, R; Gamarra, R F; Gambetta, S; García, B; Gámez, D García; Garcia-Pinto, D; Gascon, A; Gemmeke, H; Gesterling, K; Ghia, P L; Giaccari, U; Giller, M; Glass, H; Gold, M S; Golup, G; Albarracin, F Gomez; Berisso, M Gómez; Gonçalves, P; Gonzalez, D; Gonzalez, J G; Gookin, B; Góra, D; Gorgi, A; Gouffon, P; Gozzini, S R; Grashorn, E; Grebe, S; Griffith, N; Grigat, M; Grillo, A F; Guardincerri, Y; Guarino, F; Guedes, G P; Guzman, A; Hague, J D; Hansen, P; Harari, D; Harmsma, S; Harton, J L; Haungs, A; Hebbeker, T; Heck, D; Herve, A E; Hojvat, C; Hollon, N; Holmes, V C; Homola, P; Hörandel, J R; Horneffer, A; Hrabovský, M; Huege, T; Insolia, A; Ionita, F; Italiano, A; Jarne, C; Jiraskova, S; Josebachuili, M; Kadija, K; Kampert, K H; Karhan, P; Kasper, P; Kégl, B; Keilhauer, B; Keivani, A; Kelley, J L; Kemp, E; Kieckhafer, R M; Klages, H O; Kleifges, M; Kleinfeller, J; Knapp, J; Koang, D -H; Kotera, K; Krohm, N; Krömer, O; Kruppke-Hansen, D; Kuehn, F; Kuempel, D; Kulbartz, J K; Kunka, N; La Rosa, G; Lachaud, C; Lautridou, P; Leão, M S A B; Lebrun, D; Lebrun, P; de Oliveira, M A Leigui; Lemiere, A; Letessier-Selvon, A; Lhenry-Yvon, I; Link, K; López, R; Agüera, A Lopez; Louedec, K; Bahilo, J Lozano; Lu, L; Lucero, A; Ludwig, M; Lyberis, H; Maccarone, M C; Macolino, C; Maldera, S; Mandat, D; Mantsch, P; Mariazzi, A G; Marin, J; Marin, V; Maris, I C; Falcon, H R Marquez; Marsella, G; Martello, D; Martin, L; Martinez, H; Bravo, O Martínez; Mathes, H J; Matthews, J; Matthews, J A J; Matthiae, G; Maurizio, D; Mazur, P O; Medina-Tanco, G; Melissas, M; Melo, D; Menichetti, E; Menshikov, A; Mertsch, P; Meurer, C; Mićanović, S; Micheletti, M I; Miller, W; Miramonti, L; Molina-Bueno, L; Mollerach, S; Monasor, M; Ragaigne, D Monnier; Montanet, F; Morales, B; Morello, C; Moreno, E; Moreno, J C; Morris, C; Mostafá, M; Moura, C A; Mueller, S; Muller, M A; Müller, G; Münchmeyer, M; Mussa, R; Navarra, G; Navarro, J L; Navas, S; Necesal, P; Nellen, L; Nelles, A; Neuser, J; Nhung, P T; Niemietz, L; Nierstenhoefer, N; Nitz, D; Nosek, D; Nožka, L; Nyklicek, M; Oehlschläger, J; Olinto, A; Oliva, P; Olmos-Gilbaja, V M; Ortiz, M; Pacheco, N; Selmi-Dei, D Pakk; Palatka, M; Pallotta, J; Palmieri, N; Parente, G; Parizot, E; Parra, A; Parsons, R D; Pastor, S; Paul, T; Pech, M; Pȩkala, J; Pelayo, R; Pepe, I M; Perrone, L; Pesce, R; Petermann, E; Petrera, S; Petrinca, P; Petrolini, A; Petrov, Y; Petrovic, J; Pfendner, C; Phan, N; Piegaia, R; Pierog, T; Pieroni, P; Pimenta, M; Pirronello, V; Platino, M; Ponce, V H; Pontz, M; Privitera, P; Prouza, M; Quel, E J; Querchfeld, S; Rautenberg, J; Ravel, O; Ravignani, D; Revenu, B; Ridky, J; Riggi, S; Risse, M; Ristori, P; Rivera, H; Rizi, V; Roberts, J; Robledo, C; de Carvalho, W Rodrigues; Rodriguez, G; Martino, J Rodriguez; Rojo, J Rodriguez; Rodriguez-Cabo, I; Rodríguez-Frías, M D; Ros, G; Rosado, J; Rossler, T; Roth, M; Rouillé-d'Orfeuil, B; Roulet, E; Rovero, A C; Rühle, C; Salamida, F; Salazar, H; Salina, G; Sánchez, F; Santo, C E; Santos, E; Santos, E M; Sarazin, F; Sarkar, B; Sarkar, S; Sato, R; Scharf, N; Scherini, V; Schieler, H; Schiffer, P; Schmidt, A; Schmidt, F; Scholten, O; Schoorlemmer, H; Schovancova, J; Schovánek, P; Schröder, F; Schulte, S; Schuster, D; Sciutto, S J; Scuderi, M; Segreto, A; Settimo, M; Shadkam, A; Shellard, R C; Sidelnik, I; Sigl, G; Lopez, H H Silva; Śmiałkowski, A; Šmída, R; Snow, G R; Sommers, P; Sorokin, J; Spinka, H; Squartini, R; Stanic, S; Stapleton, J; Stasielak, J; Stephan, M; Strazzeri, E; Stutz, A; Suarez, F; Suomijärvi, T; Supanitsky, A D; Šuša, T; Sutherland, M S; Swain, J; Szadkowski, Z; Szuba, M; Tamashiro, A; Tapia, A; Tartare, M; Taşcău, O; Ruiz, C G Tavera; Tcaciuc, R; Tegolo, D; Thao, N T; Thomas, D; Tiffenberg, J; Timmermans, C; Tiwari, D K; Tkaczyk, W; Peixoto, C J Todero; Tomé, B; Tonachini, A; Travnicek, P; Tridapalli, D B; Tristram, G; Trovato, E; Tueros, M; Ulrich, R; Unger, M; Urban, M; Galicia, J F Valdés; Valiño, I; Valore, L; Berg, A M van den; Varela, E; Cárdenas, B Vargas; Vázquez, J R; Vázquez, R A; Veberič, D; Verzi, V; Vicha, J; Videla, M; Villaseñor, L; Wahlberg, H; Wahrlich, P; Wainberg, O; Walz, D; Warner, D; Watson, A A; Weber, M; Weidenhaupt, K; Weindl, A; Westerhoff, S; Whelan, B J; Wieczorek, G; Wiencke, L; Wilczyńska, B; Wilczyński, H; Will, M; Williams, C; Winchen, T; Winnick, M G; Wommer, M; Wundheiler, B; Yamamoto, T; Yapici, T; Younk, P; Yuan, G; Yushkov, A; Zamorano, B; Zas, E; Zavrtanik, D; Zavrtanik, M; Zaw, I; Zepeda, A; Silva, M Zimbres; Ziolkowski, M

    2011-01-01

    We present a comprehensive study of the influence of the geomagnetic field on the energy estimation of extensive air showers with a zenith angle smaller than $60^\\circ$, detected at the Pierre Auger Observatory. The geomagnetic field induces an azimuthal modulation of the estimated energy of cosmic rays up to the ~2% level at large zenith angles. We present a method to account for this modulation of the reconstructed energy. We analyse the effect of the modulation on large scale anisotropy searches in the arrival direction distributions of cosmic rays. At a given energy, the geomagnetic effect is shown to induce a pseudo-dipolar pattern at the percent level in the declination distribution that needs to be accounted for.

  8. Effects of energy-spectrum broadening in alloyed semiconductor superlattices

    OpenAIRE

    Ushakov, D.V.; Kononenko, V.K.; Manak, I. S.

    1999-01-01

    The density of energy states is calculated for alloyed semiconductor superlattices for different excitation levels with cllowance for the effects of screening and fluctuatio.zs of impurity -oncentrations. The influence of the state density tails on spontaneous-emission spectra is investigated for cross-over transitions and in a model without a selection rule for the electron wave vector. Account for the state density tails allows one to describe the longwave wing and shape of spon...

  9. Single particle spectrum and binding energy of nuclear matter

    OpenAIRE

    Baldo, M; Fiasconaro, A.

    2000-01-01

    In non-relativistic Brueckner calculations of nuclear matter, the self-consistent single particle potential is strongly momentum dependent. To simplify the calculations, a parabolic approximation is often used in the literature. The variation in the binding energy value introduced by the parabolic approximation is quantitatively analyzed in detail. It is found that the approximation can introduce an uncertainty of 1-2 MeV near the saturation density.

  10. On the groundstate energy spectrum of magnetic knots and links

    International Nuclear Information System (INIS)

    By using analytical results for the constrained minimum energy of magnetic knots we determine the influence of internal twist on the minimum magnetic energy levels of knots and links, and by using ropelength data from the RIDGERUNNER tightening algorithm (Ashton et al 2011 Exp. Math. 20 57–90) we obtain the groundstate energy spectra of the first 250 prime knots and 130 prime links. The two spectra are found to follow an almost identical logarithmic law. By assuming that the number of knot types grows exponentially with the topological crossing number, we show that this generic behavior can be justified by a general relationship between ropelength and crossing number, which is in good agreement with former analytical estimates (Buck and Simon 1999 Topol. Appl. 91 245–57, Diao 2003 J. Knot Theory Ramifications 12 1–16). Moreover, by considering the ropelength averaged over a given knot family, we establish a new connection between the averaged ropelength and the topological crossing number of magnetic knots. (paper)

  11. Energy spectrum of UHECRs measured by newly constructed fluorescence detectors in Telescope Array experiment

    Directory of Open Access Journals (Sweden)

    Fujii Toshihiro

    2013-06-01

    Full Text Available Telescope Array (TA experiment is the largest hybrid detector to observe ultra-high energy cosmic rays (UHECRs in the northern hemisphere. In the TA experiment, we newly designed and constructed 24 fluorescence detectors (FDs located at two stations. We report the energy spectrum of UHECRs with energies above 1017.5 eV from analyzing data collected by the new FDs during the first 3.7 years in monocular mode.

  12. All-particle cosmic ray energy spectrum measured with 26 IceTop stations

    OpenAIRE

    IceCube Collaboration; Abbasi, R.; Abdou, Y.; Abu-Zayyad, T.; Ackermann, M; Adams, J.; Aguilar, J.A.; Ahlers, M.; Altmann, D; Andeen, K; Auffenberg, J.; Bai, X.; Baker, M.; Barwick, S. W.; Baum, V.

    2012-01-01

    We report on a measurement of the cosmic ray energy spectrum with the IceTop air shower array, the surface component of the IceCube Neutrino Observatory at the South Pole. The data used in this analysis were taken between June and October, 2007, with 26 surface stations operational at that time, corresponding to about one third of the final array. The fiducial area used in this analysis was 0.122 km^2. The analysis investigated the energy spectrum from 1 to 100 PeV measured for three differen...

  13. Energy spectrum and phase diagrams of two-sublattice hard-core boson model

    Directory of Open Access Journals (Sweden)

    I.V. Stasyuk

    2013-06-01

    Full Text Available The energy spectrum, spectral density and phase diagrams have been obtained for two-sublattice hard-core boson model in frames of random phase approximation approach. Reconstruction of boson spectrum at the change of temperature, chemical potential and energy difference between local positions in sublattices is studied. The phase diagrams illustrating the regions of existence of a normal phase which can be close to Mott-insulator (MI or charge-density (CDW phase diagrams as well as the phase with the Bose-Einstein condensate (SF phase are built.

  14. Improved Energy Detector for Wideband Spectrum Sensing in Cognitive Radio Networks

    Directory of Open Access Journals (Sweden)

    Y. Eghbali

    2014-04-01

    Full Text Available In this paper, an improved energy detector for a wideband spectrum sensing is proposed. For a better detection of the spectrum holes the overall band is divided into equal non-overlapping sub-bands. The main objective is to determine the detection thresholds for each of these subbands jointly. By defining the problem as an optimization problem, we aim to find the maximum aggregated opportunistic throughput of cognitive radio networks. Introducing practical constraints to this optimization problem will change the problem into a convex and solvable one. The results of this paper show that the proposed improved energy detector will increase the aggregated throughput considerably.

  15. Elastic anisotropy of crystals

    Directory of Open Access Journals (Sweden)

    Christopher M. Kube

    2016-09-01

    Full Text Available An anisotropy index seeks to quantify how directionally dependent the properties of a system are. In this article, the focus is on quantifying the elastic anisotropy of crystalline materials. Previous elastic anisotropy indices are reviewed and their shortcomings discussed. A new scalar log-Euclidean anisotropy measure AL is proposed, which overcomes these deficiencies. It is based on a distance measure in a log-Euclidean space applied to fourth-rank elastic tensors. AL is an absolute measure of anisotropy where the limiting case of perfect isotropy yields zero. It is a universal measure of anisotropy applicable to all crystalline materials. Specific examples of strong anisotropy are highlighted. A supplementary material provides an anisotropy table giving the values of AL for 2,176 crystallite compounds.

  16. The Cosmic Ray Energy Spectrum Observed with the Surface Detector of the Telescope Array Experiment

    CERN Document Server

    Abu-Zayyad, T; Allen, M; Anderson, R; Azuma, R; Barcikowski, E; Belz, J W; Bergman, D R; Blake, S A; Cady, R; Cheon, B G; Chiba, J; Chikawa, M; Cho, E J; Cho, W R; Fujii, H; Fujii, T; Fukuda, T; Fukushima, M; Hanlon, W; Hayashi, K; Hayashi, Y; Hayashida, N; Hibino, K; Hiyama, K; Honda, K; Iguchi, T; Ikeda, D; Ikuta, K; Inoue, N; Ishii, T; Ishimori, R; Ivanov, D; Iwamoto, S; Jui, C C H; Kadota, K; Kakimoto, F; Kalashev, O; Kanbe, T; Kasahara, K; Kawai, H; Kawakami, S; Kawana, S; Kido, E; Kim, H B; Kim, H K; Kim, J H; Kim, J H; Kitamoto, K; Kitamura, S; Kitamura, Y; Kobayashi, K; Kobayashi, Y; Kondo, Y; Kuramoto, K; Kuzmin, V; Kwon, Y J; Lim, S I; Machida, S; Martens, K; Martineau, J; Matsuda, T; Matsuura, T; Matsuyama, T; Matthews, J N; Minamino, M; Miyata, K; Murano, Y; Myers, I; Nagasawa, K; Nagataki, S; Nakamura, T; Nam, S W; Nonaka, T; Ogio, S; Ohnishi, M; Ohoka, H; Oki, K; Oku, D; Okuda, T; Oshima, A; Ozawa, S; Park, I H; Pshirkov, M S; Rodriguez, D C; Roh, S Y; Rubtsov, G; Ryu, D; Sagawa, H; Sakurai, N; Sampson, A L; Scott, L M; Shah, P D; Shibata, F; Shibata, T; Shimodaira, H; Shin, B K; Shin, J I; Shirahama, T; Smith, J D; Sokolsky, P; Sonley, T J; Springer, R W; Stokes, B T; Stratton, S R; Stroman, T; Suzuki, S; Takahashi, Y; Takeda, M; Taketa, A; Takita, M; Tameda, Y; Tanaka, H; Tanaka, K; Tanaka, M; Thomas, S B; Thomson, G B; Tinyakov, P; Tkachev, I; Tokuno, H; Tomida, T; Troitsky, S; Tsunesada, Y; Tsutsumi, K; Tsuyuguchi, Y; Uchihori, Y; Udo, S; Ukai, H; Vasiloff, G; Wada, Y; Wong, T; Wood, M; Yamakawa, Y; Yamane, R; Yamaoka, H; Yamazaki, K; Yang, J; Yoneda, Y; Yoshida, S; Yoshii, H; Zhou, X; Zollinger, R R; Zundel, Z

    2012-01-01

    The Telescope Array (TA) collaboration has measured the energy spectrum of ultra-high energy cosmic rays for energies above 1.6x10^(18) eV in its first three years of operation. The spectrum shows a dip at an energy of 5x10^(18) eV and a steepening at 5x10^(19) eV which is consistent with the expectation from the GZK cutoff. Here we use a new technique that involves generating a complete simulation of the TA surface detector. The procedure starts with shower simulations using the CORSIKA Monte Carlo program where we have solved the problems caused by use of the "thinning" approximation. This simulation method allows us to make an accurate calculation of the acceptance of the detector for the energies concerned.

  17. The effect of the geomagnetic field on cosmic ray energy estimates and large scale anisotropy searches on data from the Pierre Auger Observatory

    Energy Technology Data Exchange (ETDEWEB)

    Abreu, P.; /Lisbon, IST; Aglietta, M.; /IFSI, Turin; Ahn, E.J.; /Fermilab; Albuquerque, I.F.M.; /Sao Paulo U.; Allard, D.; /APC, Paris; Allekotte, I.; /Centro Atomico Bariloche; Allen, J.; /New York U.; Allison, P.; /Ohio State U.; Alvarez Castillo, J.; /Mexico U., ICN; Alvarez-Muniz, J.; /Santiago de Compostela U.; Ambrosio, M.; /Naples U. /INFN, Naples /Nijmegen U., IMAPP

    2011-11-01

    We present a comprehensive study of the influence of the geomagnetic field on the energy estimation of extensive air showers with a zenith angle smaller than 60{sup o}, detected at the Pierre Auger Observatory. The geomagnetic field induces an azimuthal modulation of the estimated energy of cosmic rays up to the {approx} 2% level at large zenith angles. We present a method to account for this modulation of the reconstructed energy. We analyse the effect of the modulation on large scale anisotropy searches in the arrival direction distributions of cosmic rays. At a given energy, the geomagnetic effect is shown to induce a pseudo-dipolar pattern at the percent level in the declination distribution that needs to be accounted for. In this work, we have identified and quantified a systematic uncertainty affecting the energy determination of cosmic rays detected by the surface detector array of the Pierre Auger Observatory. This systematic uncertainty, induced by the influence of the geomagnetic field on the shower development, has a strength which depends on both the zenith and the azimuthal angles. Consequently, we have shown that it induces distortions of the estimated cosmic ray event rate at a given energy at the percent level in both the azimuthal and the declination distributions, the latter of which mimics an almost dipolar pattern. We have also shown that the induced distortions are already at the level of the statistical uncertainties for a number of events N {approx_equal} 32 000 (we note that the full Auger surface detector array collects about 6500 events per year with energies above 3 EeV). Accounting for these effects is thus essential with regard to the correct interpretation of large scale anisotropy measurements taking explicitly profit from the declination distribution.

  18. An Energy-Efficient Game-Theory-Based Spectrum Decision Scheme for Cognitive Radio Sensor Networks

    Directory of Open Access Journals (Sweden)

    Shelly Salim

    2016-06-01

    Full Text Available A cognitive radio sensor network (CRSN is a wireless sensor network in which sensor nodes are equipped with cognitive radio. In this paper, we propose an energy-efficient game-theory-based spectrum decision (EGSD scheme for CRSNs to prolong the network lifetime. Note that energy efficiency is the most important design consideration in CRSNs because it determines the network lifetime. The central part of the EGSD scheme consists of two spectrum selection algorithms: random selection and game-theory-based selection. The EGSD scheme also includes a clustering algorithm, spectrum characterization with a Markov chain, and cluster member coordination. Our performance study shows that EGSD outperforms the existing popular framework in terms of network lifetime and coordination overhead.

  19. An Energy-Efficient Game-Theory-Based Spectrum Decision Scheme for Cognitive Radio Sensor Networks.

    Science.gov (United States)

    Salim, Shelly; Moh, Sangman

    2016-01-01

    A cognitive radio sensor network (CRSN) is a wireless sensor network in which sensor nodes are equipped with cognitive radio. In this paper, we propose an energy-efficient game-theory-based spectrum decision (EGSD) scheme for CRSNs to prolong the network lifetime. Note that energy efficiency is the most important design consideration in CRSNs because it determines the network lifetime. The central part of the EGSD scheme consists of two spectrum selection algorithms: random selection and game-theory-based selection. The EGSD scheme also includes a clustering algorithm, spectrum characterization with a Markov chain, and cluster member coordination. Our performance study shows that EGSD outperforms the existing popular framework in terms of network lifetime and coordination overhead. PMID:27376290

  20. An Energy-Efficient Game-Theory-Based Spectrum Decision Scheme for Cognitive Radio Sensor Networks.

    Science.gov (United States)

    Salim, Shelly; Moh, Sangman

    2016-06-30

    A cognitive radio sensor network (CRSN) is a wireless sensor network in which sensor nodes are equipped with cognitive radio. In this paper, we propose an energy-efficient game-theory-based spectrum decision (EGSD) scheme for CRSNs to prolong the network lifetime. Note that energy efficiency is the most important design consideration in CRSNs because it determines the network lifetime. The central part of the EGSD scheme consists of two spectrum selection algorithms: random selection and game-theory-based selection. The EGSD scheme also includes a clustering algorithm, spectrum characterization with a Markov chain, and cluster member coordination. Our performance study shows that EGSD outperforms the existing popular framework in terms of network lifetime and coordination overhead.

  1. Factorization with a logarithmic energy spectrum of a two-dimensional potential

    Energy Technology Data Exchange (ETDEWEB)

    Gleisberg, F., E-mail: ferdinand.gleisberg@uni-ulm.de [Institut für Quantenphysik and Center for Integrated Quantum Science and Technology, IQ" S" T, Universität Ulm, D-89069 Ulm (Germany); Volpp, M. [Institut für Quantenphysik and Center for Integrated Quantum Science and Technology, IQ" S" T, Universität Ulm, D-89069 Ulm (Germany); Schleich, W.P. [Institut für Quantenphysik and Center for Integrated Quantum Science and Technology, IQ" S" T, Universität Ulm, D-89069 Ulm (Germany); Texas A & M University Institute for Advanced Study (TIAS), Institute for Quantum Studies and Engineering (IQSE) and Department of Physics and Astronomy, Texas A & M University, College Station, TX 77843-4242 (United States)

    2015-10-23

    We propose a method to factor numbers using a single particle caught in a separable two-dimensional potential with a logarithmic energy spectrum. The particle initially prepared in the ground state is excited with high probability by a sinusoidally time-dependent perturbation into a state whose two quantum numbers represent the factors of a number encoded in the frequency of the perturbation. We discuss the limitations of our method arising from off-resonant transitions and from decoherence. - Highlights: • A new protocol for factorization of an integer into two primes is proposed. • We report an energy spectrum optimally adapted for the factorization. • A potential for our single particle spectrum was calculated numerically. • We determined a Rabi frequency for the transition into the factor state. • An explicit limit caused by decoherence for numbers to be factored is reported.

  2. An Energy-Efficient Game-Theory-Based Spectrum Decision Scheme for Cognitive Radio Sensor Networks

    Science.gov (United States)

    Salim, Shelly; Moh, Sangman

    2016-01-01

    A cognitive radio sensor network (CRSN) is a wireless sensor network in which sensor nodes are equipped with cognitive radio. In this paper, we propose an energy-efficient game-theory-based spectrum decision (EGSD) scheme for CRSNs to prolong the network lifetime. Note that energy efficiency is the most important design consideration in CRSNs because it determines the network lifetime. The central part of the EGSD scheme consists of two spectrum selection algorithms: random selection and game-theory-based selection. The EGSD scheme also includes a clustering algorithm, spectrum characterization with a Markov chain, and cluster member coordination. Our performance study shows that EGSD outperforms the existing popular framework in terms of network lifetime and coordination overhead. PMID:27376290

  3. Induced anisotropy in nanocrystalline FeCuNbSiB

    International Nuclear Information System (INIS)

    The kinetics of induced anisotropy Kind was studied in nanocrystalline Fe73.5Cu1Nb3Si13.5B9, as well as in the amorphous precursor and in amorphous Fe78B13Si9. The nanocrystalline alloy was produced from the precursor by annealing at 813 K for 1 h and possessed an average FeSi grain size of 13 nm, as determined from x-ray diffraction. Annealing in a 0.2 T field at 723--773 K, above Tc of the amorphous phase, resulted in low values of Kind. The data were compared to the micromagnetic theory of Kronmueller to determine activation energy spectra. Kind for the nanocrystalline alloy is well described by this theory, however, with an activation energy spectrum that is much narrower than for the amorphous alloys. The limiting value of the anisotropy is K∞ ∼ 13 J/m3 consistent with that expected for the anisotropy in Fe-20at%.Si with the DO3 structure

  4. Spectrum measurement with the Telescope Array Low Energy Extension (TALE) fluorescence detector

    Science.gov (United States)

    Zundel, Zachary James

    The Telescope Array (TA) experiment is the largest Ultra High Energy cosmic ray observatory in the northern hemisphere and is designed to be sensitive to cosmic ray air showers above 1018eV. Despite the substantial measurements made by TA and AUGER (the largest cosmic ray observatory in the southern hemisphere), there remains uncertainty about whether the highest energy cosmic rays are galactic or extragalactic in origin. Locating features in the cosmic ray energy spectrum below 1018eV that indicate a transition from galactic to extragalactic sources would clarify the interpretation of measurements made at the highest energies. The Telescope Array Low Energy Extension (TALE) is designed to extend the energy threshold of the TA observatory down to 1016.5eV in order to make such measurements. This dissertation details the construction, calibration, and operation of the TALE flu- orescence detector. A measurement of the flux of cosmic rays in the energy range of 1016.5 -- 1018.5eV is made using the monocular data set taken between September 2013 and January 2014. The TALE fluorescence detector observes evidence for a softening of the cosmic spectrum at 1017.25+/-0.5eV. The evidence of a change in the spectrum motivates continued study of 1016.5 -- 1018.5eV cosmic rays.

  5. On the infimum of the energy-momentum spectrum of a homogeneous Bose gas

    DEFF Research Database (Denmark)

    Cornean, Horia; Derezinski, J.; Zin, P.

    2009-01-01

    We consider second-quantized homogeneous Bose gas in a large cubic box with periodic boundary conditions at zero temperature. We discuss the energy-momentum spectrum of the Bose gas and its physical significance. We review various rigorous and heuristic results as well as open conjectures about its...

  6. A two-stage spectrum sensing scheme based on energy detection and a novel multitaper method

    Institute of Scientific and Technical Information of China (English)

    齐佩汉; 李赞; 司江勃; 熊天意

    2015-01-01

    Wideband spectrum sensing has drawn much attention in recent years since it provides more opportunities to the sec-ondary users. However, wideband spectrum sensing requires a long time and a complex mechanism at the sensing terminal. A two-stage wideband spectrum sensing scheme is considered to proceed spectrum sensing with low time consumption and high performance to tackle this predicament. In this scheme, a novel multitaper spectrum sensing (MSS) method is proposed to mitigate the poor performance of energy detection (ED) in the low signal-to-noise ratio (SNR) region. The closed-form expression of the decision threshold is derived based on the Neyman–Pearson criterion and the probability of detection in the Rayleigh fading channel is analyzed. An optimization problem is formulated to maximize the probability of detection of the proposed two-stage scheme and the average sensing time of the two-stage scheme is analyzed. Numerical results validate the efficiency of MSS and show that the two-stage spectrum sensing scheme enjoys higher performance in the low SNR region and lower time cost in the high SNR region than the single-stage scheme.

  7. Determination of the Spectral Index in the Fission Spectrum Energy Regime

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Amy Sarah [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2016-05-16

    Neutron reaction cross sections play a vital role in tracking the production and destruction of isotopes exposed to neutron fluence. They are central to the process of reconciling the initial and final atom inventories. Measurements of irradiated samples by radiochemical methods in tangent with an algorithm are used to evaluate the fluence a sample is exposed to over the course of the irradiation. This algorithm is the Isotope Production Code (IPC) created and used by the radiochemistry data assessment team at Los Alamos National Laboratory (LANL). An integral result is calculated by varying the total neutron fluence seen by a sample. A sample, irradiated in a critical assembly, will be exposed to a unique neutron flux defined by the neutron source and distance of the sample from the source. Neutron cross sections utilized are a function of the hardness of the neutron spectrum at the location of irradiation. A spectral index is used an indicator of the hardness of the neutron spectrum. Cross sections fit forms applied in IPC are collapsed from a LANL 30-group energy structure. Several decades of research and development have been performed to formalize the current IPC cross section library. Basis of the current fission spectrum neutron reaction cross section library is rooted in critical assembly experiments performed from the 1950’s through the early 1970’s at LANL. The focus of this report is development of the spectral index used an indicator of the hardness of the neutron spectrum in the fission spectrum energy regime.

  8. Power Versus Spectrum 2-D Sensing in Energy Harvesting Cognitive Radio Networks

    Science.gov (United States)

    Zhang, Yanyan; Han, Weijia; Li, Di; Zhang, Ping; Cui, Shuguang

    2015-12-01

    Energy harvester based cognitive radio is a promising solution to address the shortage of both spectrum and energy. Since the spectrum access and power consumption patterns are interdependent, and the power value harvested from certain environmental sources are spatially correlated, the new power dimension could provide additional information to enhance the spectrum sensing accuracy. In this paper, the Markovian behavior of the primary users is considered, based on which we adopt a hidden input Markov model to specify the primary vs. secondary dynamics in the system. Accordingly, we propose a 2-D spectrum and power (harvested) sensing scheme to improve the primary user detection performance, which is also capable of estimating the primary transmit power level. Theoretical and simulated results demonstrate the effectiveness of the proposed scheme, in term of the performance gain achieved by considering the new power dimension. To the best of our knowledge, this is the first work to jointly consider the spectrum and power dimensions for the cognitive primary user detection problem.

  9. Spin diffusion in an inhomogeneous internal field (non equidistant energy spectrum)

    OpenAIRE

    Furman, Gregory B.; Goren, Shaul D.

    2004-01-01

    The theory of spin diffusion is extended to the case of spin lattice relaxation and spin diffusion in an inhomogeneous field in spin systems with non-equidistant energy spectrum. Two coupled equations describing the mutual relaxation and the spin diffusion of the nuclear magnetization and dipolar energy were obtained by using the method of nonequilibrium state operator. The equations were solved for short and long times approximation corresponding to the direct and diffusion relaxation regimes.

  10. Effect of edge decoration on the energy spectrum of semi-infinite lattices

    OpenAIRE

    Zhao, Yuanyuan; Li, Wei; Tao, Ruibao

    2011-01-01

    Analytical studies of the effect of edge decoration on the energy spectrum of semi-infinite one-dimensional (1D) lattice chain with Peierls phase transition and zigzag edged graphene (ZEG) are presented by means of transfer matrix method, in the frame of which the sufficient and necessary conditions for the existence of the edge states are determined. For 1D lattice chain, the zero-energy edge state exists when Peierls phase transition happens regardless whether the decoration exists or not, ...

  11. Primary CR energy spectrum and mass composition by the data of Tunka-133 array

    Directory of Open Access Journals (Sweden)

    Prosin V.V.

    2015-01-01

    Full Text Available The Cherenkov light array for the registration of extensive air showers (EAS Tunka-133 collected data during 5 winter seasons from 2009 to 2014. The differential energy spectrum of all particles and the dependence of the average maximum depth on the energy in the range of 6 ⋅ 1015–1018 eV measured for 1540 hours of observation are presented.

  12. Design of energy spectrum device for radon measuring with electrostatic collection method

    International Nuclear Information System (INIS)

    Background: This research is to take energy spectrum of α particle into consideration in the measurement of radon. Purpose: We aim to find the influence factors of screening particle energy. during the process of detector design. Methods: Based on the electrostatic collection radon measurement method, in order to study the influence factors of the measurement such as aluminum foil and air layer, the reasonable radiation source and geometric model are abstracted and calculated with Geant4 software. Results: The best ranges of aluminum foil thickness and air layer thickness are obtained by analyzing their relationship with a energy, the Full Width at Half Maximum (FWHM), the energy resolution, the distance of peaks and the peaks screening power. Conclusion: With the results adopted above, the energy spectrum device is fabricated. Based on the α energy spectrum sampled in a radon chamber, the validity of this design has been proved. It provides a set of reliable data for the design of radon measuring device with electrostatic collection method. (authors)

  13. Interferometric Observation of Cosmic Microwave Background Anisotropies

    CERN Document Server

    White, M; Dragovan, M; White, Martin; Carlstrom, John E.; Dragovan, Mark

    1999-01-01

    We present a formalism for analyzing interferometric observations of Cosmic Microwave Background (CMB) anisotropy and polarization data. The formalism is based upon the ell-space expansion of the angular power spectrum favoured in recent years. Explicit discussions of maximum likelihood analysis, power spectrum reconstruction, parameter estimation, imaging and polarization are given. As an example, several calculations for the Degree Angular Scale Interferometer (DASI) and Cosmic Background Interferometer (CBI) experiments are presented.

  14. Additions to the spectrum and energy levels and critical compilation of doubly ionized boron, B III

    Science.gov (United States)

    Kramida, A. E.; Ryabtsev, A. N.; Ekberg, J. O.; Kink, I.; Mannervik, S.; Martinson, I.

    2008-08-01

    We have undertaken the study of the Li-like spectrum of doubly ionized boron, B III. The spectroscopic data have been obtained with beam-foil spectroscopy and high-resolution spark spectroscopy. The experimental work was combined with theoretical calculations using ab initio and semi-empirical techniques. About 50 new transitions have been observed, and most of the previously known lines have been measured with improved accuracy. We have also critically evaluated all previous and recent data for this spectrum. Complete data on wavelengths and energy levels based on this analysis are tabulated.

  15. The Cosmic Ray Anisotropy between 1014 and 1015 eV

    Science.gov (United States)

    Aglietta, M.; Alessandron, B.; Antonioli, P.; Arneodo, F.; Bergamasco, L.; Bertaina, M.; Castagnoli, C.; Castellina, A.; Chiavassa, A.; Castagnoli, G. C.; D'Ettore Piazzoli, B.; Di Sciascio, G.; Fulgione, W.; Galeotti, P.; Ghia, P. L.; Iacovacci, M.; Mannocchi, G.; Morello, C.; Navarra, G.; Saavedra, O.; Trinchero, G. C.; Valchierotti, S.; Vallania, P.; Vernetto, S.; Vigorito, C.; EAS-TOP Collaboration

    2003-07-01

    The study of the anisotropy of the arrival directions is an essential and complementary to ol, with respect to the energy spectrum and composition, to investigate the origin and propagation of cosmic rays primaries. In particular, the study of the evolution of the CR anisotropy over primary energy can be very powerful for the interpretation of the knee in the CR primary spectrum. By means of the EAS-TOP data (four years) we have reported an anisotropy measurement at primary energy E0 ≈ 1014 eV [1], with amplitude Asid,δ=0° = (3.7 ± 0.6) · 10-4 and phase φ = (1.8 ± 0.5) hr LST, at a significance level 6.5 s.d. The use of the full EAS-TOP data set and the application of different criteria of data selection allow to extend this measurement to higher energies, up to around 1015 eV. We report here the results of the first harmonic analysis, both in solar and sidereal time, in five energy bins.

  16. The end of the galactic cosmic-ray energy spectrum - a phenomenological view

    CERN Document Server

    Hörandel, J R; Timokhin, A V; Hoerandel, Joerg R.

    2005-01-01

    Two structures in the all-particle energy spectrum of cosmic rays, the knee at 4 PeV and the second knee around 400 PeV are proposed to be explained by a phenomenological model, the poly gonato model, connecting direct and indirect measurements. Within this approach the knee is caused by a successive cut-off of the flux for individual elements starting with protons at 4.5 PeV. The second knee is interpreted as the end of the stable nuclei of the periodic table. To check some key features of this model calculations of the cosmic ray energy spectrum and the propagation path length at energies from 10^14 to 10^19 eV have been performed within the framework of a combined approach based on the diffusion model of cosmic rays and a direct simulation of charged-particle trajectories in the Galaxy.

  17. Integration of Semiconducting Sulfides for Full-Spectrum Solar Energy Absorption and Efficient Charge Separation.

    Science.gov (United States)

    Zhuang, Tao-Tao; Liu, Yan; Li, Yi; Zhao, Yuan; Wu, Liang; Jiang, Jun; Yu, Shu-Hong

    2016-05-23

    The full harvest of solar energy by semiconductors requires a material that simultaneously absorbs across the whole solar spectrum and collects photogenerated electrons and holes separately. The stepwise integration of three semiconducting sulfides, namely ZnS, CdS, and Cu2-x S, into a single nanocrystal, led to a unique ternary multi-node sheath ZnS-CdS-Cu2-x S heteronanorod for full-spectrum solar energy absorption. Localized surface plasmon resonance (LSPR) in the nonstoichiometric copper sulfide nanostructures enables effective NIR absorption. More significantly, the construction of pn heterojunctions between Cu2-x S and CdS leads to staggered gaps, as confirmed by first-principles simulations. This band alignment causes effective electron-hole separation in the ternary system and hence enables efficient solar energy conversion.

  18. High-energy spectrum and zenith-angle distribution of atmospheric neutrinos

    CERN Document Server

    Sinegovsky, S I; Sinegovskaya, T S

    2011-01-01

    High-energy neutrinos, arising from decays of mesons produced through the collisions of cosmic ray particles with air nuclei, form the background in the astrophysical neutrino detection problem. An ambiguity in high-energy behavior of pion and especially kaon production cross sections for nucleon-nucleus collisions may affect essentially the calculated neutrino flux. We present results of the calculation of the energy spectrum and zenith-angle distribution of the muon and electron atmospheric neutrinos in the energy range 10 GeV to 10 PeV. The calculation was performed with usage of known hadronic models (QGSJET-II-03, SIBYLL 2.1, Kimel & Mokhov) for two of the primary spectrum parametrizations, by Gaisser & Honda and by Zatsepin & Sokolskaya. The comparison of the calculated muon neutrino spectrum with the IceCube40 experiment data make it clear that even at energies above 100 TeV the prompt neutrino contribution is not so apparent because of tangled uncertainties of the strange (kaons) and charm...

  19. Development of computer software for neutron energy spectrum adjustment in research reactors

    Directory of Open Access Journals (Sweden)

    Iqbal Masood

    2009-01-01

    Full Text Available A computer program has been developed for neutron energy spectrum adjustment using the deconvolution method. The BUNKI-based algorithm has been implemented to converge quickly yielding calculated neutron energy spectrum which is in good agreement with theoretical predictions. The foil activation data have been used as an input for each unfolding technique and various activation foils including Au-197, Al-27, Ni-58, Co-59, and Mg-24 covering thermal to fast energy range have been utilized. The group cross-section values were derived from the data given in the pre-processed cross-section libraries in ENDF-6 format of IRDF-90/NMF-G. Firstly, virtual approach was used for neutron energy spectrum adjustment. In this case, the activity of foils before and after the adjustment was almost the same but the flux had the maximum error of 14%. Secondly, the experimental measured activity of the threshold foils was then used for a real system. The activity of the threshold foils before and after the neutron energy adjustment had the maximum error of 33%.

  20. The high-energy gamma-ray fluence and energy spectrum of GRB 970417a from observations with Milagrito

    CERN Document Server

    Atkins, R; Berley, D; Chen, M L; Coyne, D G; Dingus, B L; Dorfan, D E; Ellsworth, R W; Evans, D; Falcone, A D; Fleysher, L; Fleysher, R; Gisler, G; Sánchez, M M G; Goodman, J A; Haines, T J; Hoffman, C M; Hugenberger, S; Kelley, L A; Klein, S; Leonor, I; McCullough, J F; McEnery, J E; Miller, R S; Mincer, A I; Morales, M F; Némethy, P; Ryan, J M; Samuelson, F W; Shen, B; Shoup, A L; Sinnis, C; Smith, A J; Sullivan, G W; Tümer, T O; Wang, K; Wascko, M O; Westerhoff, S; Williams, D A; Yang, T; Yodh, G B

    2003-01-01

    Evidence of TeV emission from GRB970417a has been previously reported using data from the Milagrito detector. Constraints on the TeV fluence and the energy spectrum are now derived using additional data from a scaler system that recorded the rate of signals from the Milagrito photomultipliers. This analysis shows that if emission from GRB970417a has been observed, it must contain photons with energies above 650 GeV. Some consequences of this observation are discussed.

  1. Corrections on energy spectrum and scatterings for fast neutron radiography at NECTAR facility

    CERN Document Server

    Shu-Quan, Liu; Hang, Li; Yu-Bin, Zou; Yuan-Rong, Lu; Zhi-Yu, Guo

    2013-01-01

    Neutron spectrum and scattered neutrons caused distortions are major problems in fast neutron radiography and should be considered for improving the image quality. This paper puts emphasis on the removal of these image distortions and deviations for fast neutron radiography performed at the NECTAR facility of the research reactor FRM-II in Technische Universit\\"at M\\"unchen (TUM), Germany. The NECTAR energy spectrum is analyzed and established to modify the influence caused by neutron spectrum, as well as the Point Scattered Function (PScF) simulated by the Monte-Carlo program MCNPX is used to evaluate scattering effects from the object and improve images qualities. Good analysis results prove the sounded effects of above two corrections.

  2. Corrections on energy spectrum and scattering for fast neutron radiography at NECTAR facility

    International Nuclear Information System (INIS)

    Distortions caused by the neutron spectrum and scattered neutrons are major problems in fast neutron radiography and should be considered for improving the image quality. This paper puts emphasis on the removal of these image distortions and deviations for fast neutron radiography performed at the NECTAR facility of the research reactor FRM-Ⅱ in Technische Universitaet Mounchen (TUM), Germany. The NECTAR energy spectrum is analyzed and established to modify the influence caused by the neutron spectrum, and the Point Scattered Function (PScF) simulated by the Monte-Carlo program MCNPX is used to evaluate scattering effects from the object and improve image quality. Good analysis results prove the sound effects of the above two corrections. (authors)

  3. Neutrino Anisotropies after Planck

    CERN Document Server

    Gerbino, Martina; Said, Najla

    2013-01-01

    We present new constraints on the rest-frame sound speed, c_eff^2, and the viscosity parameter, c_vis^2, of the Cosmic Neutrino Background from the recent measurements of the Cosmic Microwave Background anisotropies provided by the Planck satellite. While broadly consistent with the ex- pectations of c_eff^2 = c_vis^2 = 1/3 in the standard scenario, the Planck dataset hints for a higher value of the viscosity parameter, with c_vis^2 = 0.60 +/- 0.18 at 68% c.l., and a lower value of the sound speed, with c_eff^2 = 0.304 +/- 0.013 at 68% c.l.. We find a correlation between the neutrino parameters and the lensing amplitude of the temperature power spectrum A_L. When the latter parameter is allowed to vary, we find a better consistency with the standard model with c_vis^2 = 0.51 +/- 0.22, c_eff^2 = 0.311 +/- 0.019 and A_L = 1.08 +/- 0.18 at 68% c.l.. This result indicates that the anomalous large value of A_L measured by Planck could be connected to non-standard neutrino properties. Including additional datasets ...

  4. Improved Measurement of the Branching Fraction and Energy Spectrum of eta' from Upsilon(1S) Decays

    CERN Document Server

    Aquines, O; Adams, G S; Alexander, J P; Anderson, M; Aquines, O; Artuso, M; Asner, D M; Athar, S B; Berkelman, K; Besson, D; Blusk, S; Bonvicini, G; Briere, R A; Brock, I; Butt, J; Cassel, D G; Cawlfield, C; Chen, J; Cinabro, D; Coan, T E; Cronin-Hennessy, D; Csorna, S E; Cummings, J P; Danko, I; Dobbs, S; Duboscq, J E; Dubrovin, M; Dytman, S A; Ecklund, K M; Edwards, K W; Ehrlich, R; Eisenstein, B I; Ernst, J; Ferguson, T; Fields, L; Galik, R S; Gao, K Y; Gao, Y S; Gibbons, L; Gong, D T; Gray, R; Gray, S W; Hartill, D L; He, Q; Heltsley, B K; Hertz, D; Hietala, J; Huang, G S; Insler, J; Jones, C D; Kandaswamy, J; Karliner, I; Kim, D; Klein, T; Kreinick, D L; Kubota, Y; Kuznetsov, V E; Lang, B W; Li, J; Li, Z; Lincoln, A; Liu, F; Love, W; Lowrey, N; López, A; Mahlke-Krüger, H; Mehrabyan, S S; Menaa, N; Metreveli, Z V; Miller, D H; Mountain, R; Muramatsu, H; Méndez, H; Naik, P; Napolitano, J; Nisar, S; Onyisi, P U E; Park, C S; Patel, R; Patterson, J R; Pavlunin, V; Pedlar, T K; Peterson, D; Pivarski, J; Poling, R; Potlia, V; Ramírez, J; Randrianarivony, K; Redjimi, R; Riley, D; Rosner, J L; Rubin, P; Ryd, A; Sadoff, A J; Sanghi, B; Savinov, V; Schwarthoff, H; Scott, A W; Sedlack, C; Selen, M; Seth, K K; Severini, H; Shepherd, M R; Shi, X; Shipsey, I P J; Sia, R; Skwarnicki, T; Smith, A; Stone, S; Stroiney, S; Sun, W M; Tatishvili, G T; Thorndike, E H; Tomaradze, A G; Vogel, H; Wang, J C; Watkins, M E; Weinberger, M; White, E J; Wilksen, T; Wiss, J; Xin, B; Yang, F; Yelton, J; Zhang, K; Zweber, P; al, et

    2006-01-01

    We present an improved measurement of the eta' meson energy spectrum in Upsilon(1S) decays, using 1.2 fb^{-1} of data taken at the Upsilon(1S) center-of-mass energy with the CLEO III detector. We compare our results with models of the eta' gluonic form factor that have been suggested to explain the unexpectedly large B to eta' X_s rate. Models based on perturbative QCD fail to fit the data for large eta' energies, and thus an explanation outside the realm of the Standard Model or an improved understanding of non-perturbative QCD effects may be needed to account for this large rate.

  5. The Cosmic Ray Energy Spectrum and Related Measurements with the Pierre Auger Observatory

    Energy Technology Data Exchange (ETDEWEB)

    Abraham, : J.; Abreu, P.; Aglietta, M.; Aguirre, C.; Ahn, E.J.; Allard, D.; Allekotte, I.; Allen, J.; Alvarez-Muniz, J.; Ambrosio, M.; Anchordoqui, L.

    2009-06-01

    These are presentations to be presented at the 31st International Cosmic Ray Conference, in Lodz, Poland during July 2009. It consists of the following presentations: (1) Measurement of the cosmic ray energy spectrum above 10{sup 18} eV with the Pierre Auger Observatory; (2) The cosmic ray flux observed at zenith angles larger than 60 degrees with the Pierre Auger Observatory; (3) Energy calibration of data recorded with the surface detectors of the Pierre Auger Observatory; (4) Exposure of the Hybrid Detector of The Pierre Auger Observatory; and (5) Energy scale derived from Fluorescence Telescopes using Cherenkov Light and Shower Universality.

  6. The knee in the cosmic ray energy spectrum from the simultaneous EAS charged particles and muon density spectra

    CERN Document Server

    Bijay, Biplab; Bhadra, Arunava

    2015-01-01

    In this work we examine with the help of Monte Carlo simulation whether a consistent primary energy spectrum of cosmic rays emerges from both the experimentally observed total charged particles and muon size spectra of cosmic ray extensive air showers considering primary composition may or may not change beyond the knee of the energy spectrum. It is found that EAS-TOP observations consistently infer a knee in the primary energy spectrum provided the primary is pure unchanging iron whereas no consistent primary spectrum emerges from simultaneous use of the KASCADE observed total charged particle and muon spectra. However, it is also found that when primary composition changes across the knee the estimation of spectral index of total charged particle spectrum is quite tricky, depends on the choice of selection of points near the knee in the size spectrum.

  7. Neutron energy spectrum influence on irradiation hardening and microstructural development of tungsten

    Science.gov (United States)

    Fukuda, Makoto; Kiran Kumar, N. A. P.; Koyanagi, Takaaki; Garrison, Lauren M.; Snead, Lance L.; Katoh, Yutai; Hasegawa, Akira

    2016-10-01

    Neutron irradiation to single crystal pure tungsten was performed in the mixed spectrum High Flux Isotope Reactor (HFIR). To investigate the influences of neutron energy spectrum, the microstructure and irradiation hardening were compared with previous data obtained from the irradiation campaigns in the mixed spectrum Japan Material Testing Reactor (JMTR) and the sodium-cooled fast reactor Joyo. The irradiation temperatures were in the range of ∼90-∼800 °C and fast neutron fluences were 0.02-9.00 × 1025 n/m2 (E > 0.1 MeV). Post irradiation evaluation included Vickers hardness measurements and transmission electron microscopy. The hardness and microstructure changes exhibited a clear dependence on the neutron energy spectrum. The hardness appeared to increase with increasing thermal neutron flux when fast fluence exceeds 1 × 1025 n/m2 (E > 0.1 MeV). Irradiation induced precipitates considered to be χ- and σ-phases were observed in samples irradiated to >1 × 1025 n/m2 (E > 0.1 MeV), which were pronounced at high dose and due to the very high thermal neutron flux of HFIR. Although the irradiation hardening mainly caused by defects clusters in a low dose regime, the transmutation-induced precipitation appeared to impose additional significant hardening of the tungsten.

  8. Contribution from individual nearby sources to the spectrum of high-energy cosmic-ray electrons

    Energy Technology Data Exchange (ETDEWEB)

    Sedrati, R., E-mail: rafik.sedrati@univ-annaba.org; Attallah, R.

    2014-04-01

    In the last few years, very important data on high-energy cosmic-ray electrons and positrons from high-precision space-born and ground-based experiments have attracted a great deal of interest. These particles represent a unique probe for studying local comic-ray accelerators because they lose energy very rapidly. These energy losses reduce the lifetime so drastically that high-energy cosmic-ray electrons can attain the Earth only from rather local astrophysical sources. This work aims at calculating, by means of Monte Carlo simulation, the contribution from some known nearby astrophysical sources to the cosmic-ray electron/positron spectra at high energy (≥10GeV). The background to the electron energy spectrum from distant sources is determined with the help of the GALPROP code. The obtained numerical results are compared with a set of experimental data.

  9. All-particle cosmic ray energy spectrum measured with 26 IceTop stations

    CERN Document Server

    Abbasi, R; Abu-Zayyad, T; Ackermann, M; Adams, J; Aguilar, J A; Ahlers, M; Altmann, D; Andeen, K; Auffenberg, J; Bai, X; Baker, M; Barwick, S W; Baum, V; Bay, R; Alba, J L Bazo; Beattie, K; Beatty, J J; Bechet, S; Becker, J K; Becker, K -H; Bell, M; Benabderrahmane, M L; BenZvi, S; Berdermann, J; Berghaus, P; Berley, D; Bernardini, E; Bertrand, D; Besson, D Z; Bindig, D; Bissok, M; Blaufuss, E; Blumenthal, J; Boersma, D J; Bohm, C; Bose, D; Böser, S; Botner, O; Brayeur, L; Brown, A M; Buitink, S; Caballero-Mora, K S; Carson, M; Casier, M; Chirkin, D; Christy, B; Clevermann, F; Cohen, S; Cowen, D F; Silva, A H Cruz; D'Agostino, M V; Danninger, M; Daughhetee, J; Davis, J C; De Clercq, C; Degner, T; Descamps, F; Desiati, P; de Vries-Uiterweerd, G; DeYoung, T; Díaz-Vélez, J C; Dreyer, J; Dumm, J P; Dunkman, M; Eisch, J; Ellsworth, R W; Engdegård, O; Euler, S; Evenson, P A; Fadiran, O; Fazely, A R; Fedynitch, A; Feintzeig, J; Feusels, T; Filimonov, K; Finley, C; Fischer-Wasels, T; Flis, S; Franckowiak, A; Franke, R; Gaisser, T K; Gallagher, J; Gerhardt, L; Gladstone, L; Glüsenkamp, T; Goldschmidt, A; Goodman, J A; Góra, D; Grant, D; Groß, A; Grullon, S; Gurtner, M; Ha, C; Ismail, A Haj; Hallgren, A; Halzen, F; Han, K; Hanson, K; Heimann, P; Heinen, D; Helbing, K; Hellauer, R; Hickford, S; Hill, G C; Hoffman, K D; Hoffmann, B; Homeier, A; Hoshina, K; Huelsnitz, W; Hulth, P O; Hultqvist, K; Hussain, S; Ishihara, A; Jacobi, E; Jacobsen, J; Japaridze, G S; Johansson, H; Kappes, A; Karg, T; Karle, A; Kiryluk, J; Kislat, F; Klein, S R; Klepser, S; Köhne, J -H; Kohnen, G; Kolanoski, H; Köpke, L; Kopper, S; Koskinen, D J; Kowalski, M; Krasberg, M; Kroll, G; Kunnen, J; Kurahashi, N; Kuwabara, T; Labare, M; Laihem, K; Landsman, H; Larson, M J; Lauer, R; Lünemann, J; Madsen, J; Maruyama, R; Mase, K; Matis, H S; Meagher, K; Merck, M; Mészáros, P; Meures, T; Miarecki, S; Middell, E; Milke, N; Miller, J; Montaruli, T; Morse, R; Movit, S M; Nahnhauer, R; Nam, J W; Naumann, U; Nowicki, S C; Nygren, D R; Odrowski, S; Olivas, A; Olivo, M; O'Murchadha, A; Panknin, S; Paul, L; Heros, C Pérez de los; Pieloth, D; Posselt, J; Price, P B; Przybylski, G T; Rawlins, K; Redl, P; Resconi, E; Rhode, W; Ribordy, M; Richman, M; Riedel, B; Rodrigues, J P; Rothmaier, F; Rott, C; Ruhe, T; Rutledge, D; Ruzybayev, B; Ryckbosch, D; Sander, H -G; Santander, M; Sarkar, S; Schatto, K; Scheel, M; Schmidt, T; Schöneberg, S; Schönwald, A; Schukraft, A; Schulte, L; Schultes, A; Schulz, O; Schunck, M; Seckel, D; Semburg, B; Seo, S H; Sestayo, Y; Seunarine, S; Silvestri, A; Smith, M W E; Spiczak, G M; Spiering, C; Stamatikos, M; Stanev, T; Stezelberger, T; Stokstad, R G; Stößl, A; Strahler, E A; Ström, R; Stüer, M; Sullivan, G W; Taavola, H; Taboada, I; Tamburro, A; Ter-Antonyan, S; Tilav, S; Toale, P A; Toscano, S; Tosi, D; van Eijndhoven, N; Van Overloop, A; van Santen, J; Vehring, M; Voge, M; Walck, C; Waldenmaier, T; Wallraff, M; Walter, M; Wasserman, R; Weaver, Ch; Wendt, C; Westerhoff, S; Whitehorn, N; Wiebe, K; Wiebusch, C H; Williams, D R; Wischnewski, R; Wissing, H; Wolf, M; Wood, T R; Woschnagg, K; Xu, C; Xu, D L; Xu, X W; Yanez, J P; Yodh, G; Yoshida, S; Zarzhitsky, P; Zoll, M

    2012-01-01

    We report on a measurement of the cosmic ray energy spectrum with the IceTop air shower array, the surface component of the IceCube Neutrino Observatory at the South Pole. The data used in this analysis were taken between June and October, 2007, with 26 surface stations operational at that time, corresponding to about one third of the final array. The fiducial area used in this analysis was 0.122 km^2. The analysis investigated the energy spectrum from 1 to 100 PeV measured for three different zenith angle ranges between 0{\\deg} and 46{\\deg}. Because of the isotropy of cosmic rays in this energy range the spectra from all zenith angle intervals have to agree. The cosmic-ray energy spectrum was determined under different assumptions on the primary mass composition. Good agreement of spectra in the three zenith angle ranges was found for the assumption of pure proton and a simple two-component model. For zenith angles {\\theta} < 30{\\deg}, where the mass dependence is smallest, the knee in the cosmic ray ener...

  10. Ion irradiation-induced structure damage to botanic samples using the ion transmission energy spectrum

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    In order to study the mechanism of irradiation-induced damage ofbotanic samples caused by low energy heavy ions, transmission energy spectrum mea-surement was performed. Kidney bean slice samples 100μm in thickness were irradi-ated by 50 kev N+ ions. The irradiation beam current density was about 30μA/cm2,and the irradiation ion doses were 1×1015, 1×1016, 3×1016 and 1×1017 ions@cm-2,respectively. A target set up that could greatly reduce the incident ion current densitywas designed to achieve the damage-free measurement. The 3.2 MeV H+ transmittedion energy spectrum measurement was carried out before and after the irradiation.From the transmission ion energy spectrum, it was found that the kidney bean sliceitself was structurally inhomogeneous compared with the PET films (C10HsO4). Ourresults indicated that the average mass thickness changed little when the N+ iondose was below 3×1016 ions.cm-2, but changed obviously whcn ion dose was beyond3×1016 ions.cm-2.

  11. Calculation of Energy Spectrum of 12C Isotope by Relativistic Cluster model

    CERN Document Server

    Roshanbakht, Nafiseh

    2016-01-01

    In this paper, we have calculated the energy spectrum of 12C isotope by cluster model. The experimental results show that the "Hoyle" state at 7.65 MeV in 12C isotope has a well-developed three-alpha structure. Hence, we select a three-body system and for interaction between the clusters we use modified Yukawa potential plus coulomb potential. Then, we solve the relativistic Klein-Gordon equation using Nikiforov-Uvarov method to calculate the energy spectrum. Finally, the calculated results are compared with the experimental data. The results show that the isotope 12C should be considered as consisting of three-alpha cluster and the modified Yukawa potential is adaptable for cluster interactions.

  12. Calculation of energy spectrum of $^{12}$C isotope with modified Yukawa potential by cluster models

    Indian Academy of Sciences (India)

    MOHAMMAD REZA SHOJAE; NAFISEH ROSHAN BAKHT

    2016-10-01

    In this paper, we have calculated the energy spectrum of 12C isotope in two-cluster models, $3\\alpha$ cluster model and $^8$Be + $\\alpha$ cluster model. We use the modified Yukawa potential for interaction between theclusters and solve the Schrödinger equation using Nikiforov–Uvarov method to calculate the energy spectrum. Then, we increase the accuracy by adding spin-orbit coupling and tensor force and solve them by perturbationtheory in both models. Finally, the calculated results for both models are compared with each other and with the experimental data. The results show that the isotope $^{12}$C should be considered as a three-$\\alpha$ cluster and themodified Yukawa potential is adaptable for cluster interactions.

  13. Minimax determination of the energy spectrum of the Dirac equation in a Schwarzschild background

    CERN Document Server

    Caceres, A; Caceres, Alejandro; Doran, Chris

    2005-01-01

    We calculate the bound-state energy spectrum of the Dirac Equation in a Schwarzschild black hole background using a minimax variational method. Our method extends that of Talman to the case of non-Hermitian interactions, such as a black hole. The trial function is expressed in terms of a basis set that takes into account both the Hermitian limit of the interaction in the non-relativistic approximation, and the general behaviour of the solutions at the origin, the horizon and infinity. Using this trial function an approximation to the full complex energy bound-state spectrum is computed. We study the behaviour of the method as the coupling constant of the interaction is increased, which increases both the relativistic effects and the size of the non-Hermitian part of the interaction. Finally we confirm that the method follows the expected Hylleraas-Undheim behaviour.

  14. Measurement of the cosmic ray energy spectrum with IceTop-73

    CERN Document Server

    ,

    2013-01-01

    We report on the measurement of the all-particle cosmic ray energy spectrum with the IceTop air shower array in the energy range from 1.58 PeV to 1.26 EeV. The IceTop air shower array is the surface component of the IceCube Neutrino Observatory at the geographical South Pole. The analysis was performed using only information from IceTop. The data used in this work were taken from June 1, 2010 to May 13, 2011. During that period the IceTop array consisted of 73 stations compared to 81 in its final configuration. The measured spectrum exhibits a clear deviation from a single power law above the knee around 4PeV and below 1EeV. We observe spectral hardening around 18 PeV and steepening around 130 PeV.

  15. Measurement of the cosmic ray energy spectrum with IceTop-73

    Science.gov (United States)

    Aartsen, M. G.; Abbasi, R.; Abdou, Y.; Ackermann, M.; Adams, J.; Aguilar, J. A.; Ahlers, M.; Altmann, D.; Auffenberg, J.; Bai, X.; Baker, M.; Barwick, S. W.; Baum, V.; Bay, R.; Beatty, J. J.; Bechet, S.; Becker Tjus, J.; Becker, K.-H.; Benabderrahmane, M. L.; BenZvi, S.; Berghaus, P.; Berley, D.; Bernardini, E.; Bernhard, A.; Bertrand, D.; Besson, D. Z.; Binder, G.; Bindig, D.; Bissok, M.; Blaufuss, E.; Blumenthal, J.; Boersma, D. J.; Bohaichuk, S.; Bohm, C.; Bose, D.; Böser, S.; Botner, O.; Brayeur, L.; Bretz, H.-P.; Brown, A. M.; Bruijn, R.; Brunner, J.; Carson, M.; Casey, J.; Casier, M.; Chirkin, D.; Christov, A.; Christy, B.; Clark, K.; Clevermann, F.; Coenders, S.; Cohen, S.; Cowen, D. F.; Cruz Silva, A. H.; Danninger, M.; Daughhetee, J.; Davis, J. C.; De Clercq, C.; De Ridder, S.; Desiati, P.; de Vries, K. D.; de With, M.; DeYoung, T.; Díaz-Vélez, J. C.; Dunkman, M.; Eagan, R.; Eberhardt, B.; Eisch, J.; Ellsworth, R. W.; Euler, S.; Evenson, P. A.; Fadiran, O.; Fazely, A. R.; Fedynitch, A.; Feintzeig, J.; Feusels, T.; Filimonov, K.; Finley, C.; Fischer-Wasels, T.; Flis, S.; Franckowiak, A.; Frantzen, K.; Fuchs, T.; Gaisser, T. K.; Gallagher, J.; Gerhardt, L.; Gladstone, L.; Glüsenkamp, T.; Goldschmidt, A.; Golup, G.; Gonzalez, J. G.; Goodman, J. A.; Góra, D.; Grandmont, D. T.; Grant, D.; Groß, A.; Ha, C.; Haj Ismail, A.; Hallen, P.; Hallgren, A.; Halzen, F.; Hanson, K.; Heereman, D.; Heinen, D.; Helbing, K.; Hellauer, R.; Hickford, S.; Hill, G. C.; Hoffman, K. D.; Hoffmann, R.; Homeier, A.; Hoshina, K.; Huelsnitz, W.; Hulth, P. O.; Hultqvist, K.; Hussain, S.; Ishihara, A.; Jacobi, E.; Jacobsen, J.; Jagielski, K.; Japaridze, G. S.; Jero, K.; Jlelati, O.; Kaminsky, B.; Kappes, A.; Karg, T.; Karle, A.; Kelley, J. L.; Kiryluk, J.; Kläs, J.; Klein, S. R.; Köhne, J.-H.; Kohnen, G.; Kolanoski, H.; Köpke, L.; Kopper, C.; Kopper, S.; Koskinen, D. J.; Kowalski, M.; Krasberg, M.; Krings, K.; Kroll, G.; Kunnen, J.; Kurahashi, N.; Kuwabara, T.; Labare, M.; Landsman, H.; Larson, M. J.; Lesiak-Bzdak, M.; Leuermann, M.; Leute, J.; Lünemann, J.; Macíias, O.; Madsen, J.; Maggi, G.; Maruyama, R.; Mase, K.; Matis, H. S.; McNally, F.; Meagher, K.; Merck, M.; Meures, T.; Miarecki, S.; Middell, E.; Milke, N.; Miller, J.; Mohrmann, L.; Montaruli, T.; Morse, R.; Nahnhauer, R.; Naumann, U.; Niederhausen, H.; Nowicki, S. C.; Nygren, D. R.; Obertacke, A.; Odrowski, S.; Olivas, A.; Omairat, A.; O'Murchadha, A.; Paul, L.; Pepper, J. A.; Pérez de los Heros, C.; Pfendner, C.; Pieloth, D.; Pinat, E.; Posselt, J.; Price, P. B.; Przybylski, G. T.; Rädel, L.; Rameez, M.; Rawlins, K.; Redl, P.; Reimann, R.; Resconi, E.; Rhode, W.; Ribordy, M.; Richman, M.; Riedel, B.; Rodrigues, J. P.; Rott, C.; Ruhe, T.; Ruzybayev, B.; Ryckbosch, D.; Saba, S. M.; Salameh, T.; Sander, H.-G.; Santander, M.; Sarkar, S.; Schatto, K.; Scheriau, F.; Schmidt, T.; Schmitz, M.; Schoenen, S.; Schöneberg, S.; Schönwald, A.; Schukraft, A.; Schulte, L.; Schulz, O.; Seckel, D.; Sestayo, Y.; Seunarine, S.; Shanidze, R.; Sheremata, C.; Smith, M. W. E.; Soldin, D.; Spiczak, G. M.; Spiering, C.; Stamatikos, M.; Stanev, T.; Stasik, A.; Stezelberger, T.; Stokstad, R. G.; Stößl, A.; Strahler, E. A.; Ström, R.; Sullivan, G. W.; Taavola, H.; Taboada, I.; Tamburro, A.; Tepe, A.; Ter-Antonyan, S.; Tešić, G.; Tilav, S.; Toale, P. A.; Toscano, S.; Unger, E.; Usner, M.; Vallecorsa, S.; van Eijndhoven, N.; Van Overloop, A.; van Santen, J.; Vehring, M.; Voge, M.; Vraeghe, M.; Walck, C.; Waldenmaier, T.; Wallraff, M.; Weaver, Ch.; Wellons, M.; Wendt, C.; Westerhoff, S.; Whitehorn, N.; Wiebe, K.; Wiebusch, C. H.; Williams, D. R.; Wissing, H.; Wolf, M.; Wood, T. R.; Woschnagg, K.; Xu, C.; Xu, D. L.; Xu, X. W.; Yanez, J. P.; Yodh, G.; Yoshida, S.; Zarzhitsky, P.; Ziemann, J.; Zierke, S.; Zoll, M.

    2013-08-01

    We report on the measurement of the all-particle cosmic ray energy spectrum with the IceTop air shower array in the energy range from 1.58 PeV to 1.26 EeV. The IceTop air shower array is the surface component of the IceCube Neutrino Observatory at the geographical South Pole. The analysis was performed using only information from IceTop. The data used in this work were taken from June 1, 2010 to May 13, 2011. During that period the IceTop array consisted of 73 stations, compared to 81 in its final configuration. The measured spectrum exhibits a clear deviation from a single power law above the knee around 4 PeV and below 1 EeV. We observe spectral hardening around 18 PeV and steepening around 130 PeV.

  16. Anisotropy of rare-earth magnets

    Institute of Scientific and Technical Information of China (English)

    R.Skomski; D.J.Sellmyer

    2009-01-01

    Rare-earth intermetallics such as Nd2FeI4B and Sm-Co are widely used as high-performance permanent magnets,because they combine high magnetocrystalline anisotropy with reasonable magnetization and Curie temperature.The anisotropy is a combined effect of spin-orbit coupling and electrostatic crystal-field interactions.The main contribution comes from the rare-earth 4f electrons,which are well-screened from the crystalline environment but exhibit a strong spin-orbit coupling.In this limit,the magnetocrystalline anisotropy has a very transparent physical interpretation,the anisotropy energy essentially being equal to the energy of Hund's-rules 4f ion in the crystal field.The corresponding expression for the lowest-order uniaxial anisotropy constant K1 is used to discuss rare-earth substitutions,which have recently attracted renewed interest due to shifts in the rare-earth production and demand.Specific phenomena reviewed in this article are the enhancement of the anisotropy of Sm2Fe17 due to interstitial nitrogen,the use of Sm-Co magnets for high-temperature applications,and the comparison of rare-earth single-ion anisotropy with other single-ion and two-ion mechanisms.

  17. Energy Spectrum of Helium Confined to a Two-Dimensional Space

    Institute of Scientific and Technical Information of China (English)

    XIEWen-Fang

    2005-01-01

    Making use of the adiabatic hyperspherical approach, we report a calculation for the energy spectrum of the ground and low-excited states of a two-dimensional helium in a magnetic field. The results show that the ground and low-excited states of helium in low-dimensional space are more stable than those in three-dimensional space and there may exist more bound states.

  18. Energy spectrum of an electron confined in the hexagon-shaped quantum well

    Institute of Scientific and Technical Information of China (English)

    Yu.V.VOROBIEV; V.R.VlEIRA; P.P.HORLEY; P.N.GORLEY; J.GONZ(A)LEZ-HERN(A)NDEZ

    2009-01-01

    Considering the hexagonal-shaped quantum-scale formations on the surface of thin semiconductor films, a methodology was developed to obtain the analytical solution of the Schr(o)dinger equation when impenetrable walls of a quantum well are treated as mirrors. The results obtained allowed the calcula-tion of the space probability distributions and the energy spectrum of the particle confined in a hex-agonal-shaped well.

  19. Is the primary energy spectrum around the knee a statistical game?

    International Nuclear Information System (INIS)

    The present state of research of the shape of the energy spectrum of primary cosmic ray nuclei and the chemical composition in the region of the so-called, knee, and beyond is highly unsatisfactory. It was not very successful when using extensive air showers. In the present paper an attempt is made to explain what is the cause of such a situation. The experimental results as to which there is no doubt that they were wrongly interpreted, will be indicated

  20. Energy spectrum of the Dirac equation for the Scharzschild and Kerr fields

    Energy Technology Data Exchange (ETDEWEB)

    Ternov, I.M.; Gaina, A.B.

    1988-08-01

    We consider the effect of relativistic corrections and rotation of the central body on the structure of the energy spectrum of a particle with spin in the Schwarzchild and Kerr fields. A splitting of levels is obtained, which corresponds to the classical shift of the perihelion of the orbit and precession of the plane of the gravitational spin-orbit interaction and several nonlinear spin effects are calculated.

  1. Energy spectrum of an electron confined in the hexagon-shaped quantum well

    Institute of Scientific and Technical Information of China (English)

    Yu.; V.; VOROBIEV; V.; R.; VIEIRA; P.; P.; HORLEY; P.; N.; GORLEY; J.; GONZLEZ-HERNNDEZ

    2009-01-01

    Considering the hexagonal-shaped quantum-scale formations on the surface of thin semiconductor films, a methodology was developed to obtain the analytical solution of the Schrdinger equation when impenetrable walls of a quantum well are treated as mirrors. The results obtained allowed the calculation of the space probability distributions and the energy spectrum of the particle confined in a hex-agonal-shaped well.

  2. Energy-Based Cooperative Spectrum Sensing of SC-FDMA Systems

    Directory of Open Access Journals (Sweden)

    Fucheng Yang

    2014-07-01

    Full Text Available In this paper, we propose a frequency-hopping M-ary frequency-shift keying spectrum sensing network (FH/MFSK SSN for identifying the on/off states of the users supported by a single-carrier frequency-division multiple assess (SC-FDMA primary radio (PR system. Specifically, the spectrums of an uplink interleaved frequency-division multiple access (IFDMA PR system are monitored by a number of cognitive radio sensing nodes (CRSNs. These CRSNs distributedly detect the on/off states of users based on one of the three energy detection schemes. After the local spectrum sensing, the CRSNs transmit their detected states to a fusion centre (FC with the aid of FH/MFSK techniques. At the FC, the on/off states of the users supported the IFDMA PR system are finally classified according to either the conventional equal-gain combining (EGC scheme or the novel erasure-supported EGC (ES-EGC scheme. In this way, the on/off information about the spectrums occupied by an IFDMA PR systemcan be obtained, so that they can be exploited by a cognitive radio (CR system. For local spectrum sensing, in this paper, we consider four synchronisation scenarios concerning the synchronisation between the received IFDMA signals and the CRSNs. The performance of the FH/MFSK SSN associated with various schemes is investigated by simulations. Our studies show that the FH/MFSK SSN constitutes one of the highly reliable spectrum sensing schemes, which are capable of exploiting both the space diversity provided by local CRSNs and the frequency diversity provided by the subcarriers of IFDMA system.

  3. Statistical analysis in search for anisotropies for the observed UHECRs

    Science.gov (United States)

    Ghosh, Soumavo

    2012-07-01

    Cosmic accelerators produce particles with energies in a wide range (PeV to EeV, 1 PeV ˜ 10-15 eV, 1 EeV ˜ 10-18 eV) . The energy spectrum follows three power laws like a ` leg' structure of which the `knee' part ( ˜ 3 PeV) is of Galactic origin, the `ankle' part is unassociated with Glaxy and the highest energy source above the ankle shows evidence for extragalactic origin. In the present work various cross correlation functions are studied between the samples of observed UHECRs and and the catalogue of nearby galaxies to search for anisotropies , if any, in the arrival directions of UHECRs for identifying their possible sources. The robustness of the functions are studies through many random realizations of the original samples under considerations. Similar procedure is followed for catalogues also for comparison.

  4. Kolmogorov argument for the scaling of the energy spectrum in a stratified fluid

    Energy Technology Data Exchange (ETDEWEB)

    Bhattacharjee, Jayanta K., E-mail: jayanta.bhattacharjee@gmail.com

    2015-03-20

    In this work we show that the global energy balance part of the Kolmogorov argument for the kinetic energy spectrum in a homogeneous fluid repeated for the stratified fluid will inevitably exhibit a small deviation from perfect scaling. It is shown that an unambiguous scaling with an exponent of 11/5 can be observed only if the fluid is stably stratified in agreement with the original suggestion of Bolgiano. We find that even if the kinetic energy flux shows the predicted fall-off with wave-vector and the thermal energy (entropy) flux is constant, the kinetic energy spectrum will show a small deviation from perfect scaling. - Highlights: • A Kolmogorov argument for global energy balance for turbulence in a stratified fluid is presented. • It is seen that for unstable stratification an unambiguous argument cannot be set up. • For stable stratification there is clear Kolmogorov scenario but the flux is a combination of kinetic and thermal fluxes. • A pure Bolgiano–Obukhov scaling is seen only for wave-numbers greater than a critical wave-number. • The critical wave-number decreases as the Richardson number increases.

  5. Method to deduce the energy spectrum by the Pierre Auger Observatory

    Energy Technology Data Exchange (ETDEWEB)

    Maris, I.; Roth, M.; Schmidt, T.; Schuessler, F.; Unger, M. [Univ. Karlsruhe (Germany); Bluemer, J. [Univ. Karlsruhe (Germany); Forschungszentrum Karlsruhe (Germany)

    2007-07-01

    Taken into account the great advantage of having a hybrid detector it has been developed a method, simulation independent, to determine the energy of the comic rays recorded by the surface detector of the Pierre Auger Observatory. The method assumes that the cosmic ray flux has the same distribution in zenith angle for all energy ranges. Therefore one can relate the calorimetric measurement of the fluorescence detector of the CR energy with a SD quantity, e.g. shower size at 1000m distance from the core, corrected for the different attenuations in the atmosphere. The method of measuring and calibrating the primary energy and the influence of reconstruction uncertainties on the energy spectrum are presented. (orig.)

  6. Effects of spatial noncommutativity on energy spectrum of a trapped Bose-Einstein condensate

    CERN Document Server

    Luo, Y H; Ge, Zi-Ming; Luo, You-Hua

    2005-01-01

    In noncommutative space, we examine the problem of a noninteracting and harmonically trapped Bose-Einstein condensate, and derive a simple analytic expression for the effect of spatial noncommutativity on energy spectrum of the condensate. It indicates that the ground-state energy incorporating the spatial noncommutativity is reduced to a lower level, which depends upon the noncommutativity parameter $\\theta$. The appeared gap between the noncommutative space and commutative one for the ground-state level of the condensate should be a signal of spatial noncommutativity.

  7. Exact ultra cold neutrons' energy spectrum in gravitational quantum mechanics

    Energy Technology Data Exchange (ETDEWEB)

    Pedram, Pouria [Islamic Azad University, Department of Physics, Science and Research Branch, Tehran (Iran, Islamic Republic of)

    2013-10-15

    We find exact energy eigenvalues and eigenfunctions of the quantum bouncer in the presence of the minimal length uncertainty and the maximal momentum. This form of Generalized (Gravitational) Uncertainty Principle (GUP) agrees with various theories of quantum gravity and predicts a minimal length uncertainty proportional to {Dirac_h}{radical}({beta}) and a maximal momentum proportional to 1/{radical}({beta}), where {beta} is the deformation parameter. We also find the semiclassical energy spectrum and discuss the effects of this GUP on the transition rate of the ultra cold neutrons in gravitational spectrometers. Then, based on Nesvizhevsky's famous experiment, we obtain an upper bound on the dimensionless GUP parameter. (orig.)

  8. Energy spectrum and mass composition around the knee by EAS measurements

    International Nuclear Information System (INIS)

    Primary cosmic ray particles above energies of about 100 TeV are investigated by large-area ground-based detector installations, observing various components of the development of extensive air-showers (EAS). By such an indirect access to the primary cosmic ray spectrum a steepening of the power-law falls off at around 3-5 PeV, known as the knee has been identified. Different experimental techniques are used to deduce mass- and energy-sensitive observables of EAS experiments. The experiments involve measurements of secondary particle distributions at various observation levels and of muons deep underground as well as of observables reconstructed by measuring the air Cherenkov light emitted with the shower development in the atmosphere. Recently methods for analysing multidimensional distributions get favoured since they are able to take into account the correlations between different observables and the influence of large intrinsic fluctuations of the air-shower development. Additionally the use of a larger set of observables provides the possibility of simultaneously testing the consistency of the Monte Carlo models underlying the reconstruction procedures. From a number of experiments the existence of the knee in the primary energy spectrum is confirmed and a tendency of an increasing mean mass above the knee energy is indicated. Recent results show that the knee originates from a decrease of the flux of light primary particles, whereas heavy cosmic ray particles seem to miss a kink in the energy range of 1-10 PeV

  9. Measurements of the energy spectrum of electrons emanating from solid materials irradiated by a picosecond laser

    Energy Technology Data Exchange (ETDEWEB)

    Di Stefano, C. A., E-mail: carlosds@umich.edu; Kuranz, C. C.; Thomas, A. G. R.; Drake, R. P.; Keiter, P. A.; Rasmus, A. M.; Wan, W. C.; Joglekar, A. S.; McKelvey, A.; Zhao, Z.; Klein, S. R. [University of Michigan, Ann Arbor, Michigan 48109 (United States); Seely, J. F. [Artep, Inc., Ellicott City, Mary land 21042 (United States); Williams, G. J.; Park, J.; Chen, H.; Kemp, G. E. [Lawrence Livermore National Laboratory, Livermore, California 94551 (United States); MacDonald, M. J. [University of Michigan, Ann Arbor, Michigan 48109 (United States); SLAC National Accelerator Laboratory, Menlo Park, California 94025 (United States); Pereira, N. R. [Ecopulse, Inc., Springfield, Virginia 22150 (United States); Jarrott, L. C.; Peebles, J. [University of California, San Diego, Energy Research Center, La Jolla, California 92093 (United States); and others

    2015-04-15

    In this work, we present the results of experiments observing the properties of the electron stream generated laterally when a laser irradiates a metal. We find that the directionality of the electrons is dependent upon their energies, with the higher-energy tail of the spectrum (∼1 MeV and higher) being more narrowly focused. This behavior is likely due to the coupling of the electrons to the electric field of the laser. The experiments are performed by using the Titan laser to irradiate a metal wire, creating the electron stream of interest. These electrons propagate to nearby spectator wires of differing metals, causing them to fluoresce at their characteristic K-shell energies. This fluorescence is recorded by a crystal spectrometer. By varying the distances between the wires, we are able to probe the divergence of the electron stream, while by varying the medium through which the electrons propagate (and hence the energy-dependence of electron attenuation), we are able to probe the energy spectrum of the stream.

  10. MAGIC measurement of the Crab Nebula spectrum over three decades in energy

    CERN Document Server

    Zanin, Roberta; Carmona, Emiliano; Colin, Pierre; Cortina, Juan; Jogler, Tobias; Klepser, Stefan; Moralejo, Abelardo; Horns, Dieter; Meyer, M

    2011-01-01

    The Crab Pulsar Wind Nebula is the best studied source of $\\gamma$-ray astrophysics. The contribution of the various soft radiation fields to the Inverse Compton component of its high energy emission, the strenght of the internal magnetic field and the maximum energies reached by primary electrons are however still matter of study. The MAGIC stereoscopic system recorded almost 50 hours of Crab Nebula data in the last two years, between October 2009 and April 2011. Analysis of this data sample using the latest improvements in the MAGIC stereo software provided an unprecedented differential energy spectrum spanning three decades in energy, from 50 GeV up to 45 TeV. At low energies, the MAGIC results, combined with the Fermi/LAT data, yield a precise measurement of the Inverse Compton peak. In addition, we present light curves of the Crab Nebula at different time scales, including a measurement simultaneous to one of the Crab Nebula flares recently detected by both Fermi/LAT and AGILE. Using the MAGIC spectrum t...

  11. Magnetic surface anisotropy

    Science.gov (United States)

    Rado, George T.

    1992-02-01

    Selected aspects of magnetic surface anisotropy are reviewed. The emphasis is on methods for deducing reliable surface anisotropy values from experiments such as ferromagnetic resonance at microwave frequencies and Brillouin scattering at optical frequencies. The methods used are the "general exchange boundary condition method" and the "effective volume anisotropy method". The essence of the former is the supplementing of the equation of motion of the magnetization with the general exchange boundary condition whereas the latter consists of using the "stratagem" of effective volume anisotropy. We find that use of the general exchange boundary condition method is not only preferable in principle but often actually necessary to prevent the prediction of wrong surface anisotropy values and to permit the prediction of some observable Brillouin shifts.

  12. The Energy Spectrum and the Chemical Composition of Primary Cosmic Rays with Energies from 1014 to 1016 eV

    Science.gov (United States)

    Ogio, S.; Kakimoto, F.; Kurashina, Y.; Burgoa, O.; Harada, D.; Tokuno, H.; Yoshii, H.; Morizawa, A.; Gotoh, E.; Nakatani, H.; Nishi, K.; Shimoda, S.; Tajima, N.; Yamada, Y.; Kaneko, T.; Murakami, K.; Toyoda, Y.; Matsubara, Y.; Mizumoto, Y.; Shirasaki, Y.; Tsunesada, Y.; Miranda, P.; Velarde, A.

    2004-09-01

    We have measured extensive air showers with primary energies above 6 TeV at Mount Chacaltaya in Bolivia. The data were collected by an air shower array called the Minimum Air Shower (MAS) array starting in 2000 March. We applied an equi-intensity analysis method to the extensive air showers extended over the region of their maximum development. We varied the mixture of protons and iron in our simulations and compared these to the data to determine the mixing ratio of protons as a function of the primary energy. Using this, we derived the primary energy spectrum from 1014 to 5×1016 eV. Consequently, we conclude that the power-law index of the spectrum changes gradually around 1015.5 eV and that the obtained proton ratio decreases with increasing energy. We directly measured the longitudinal development of air showers generated by primaries with energies around the knee. We found that the average mass number of primary cosmic rays shows a steady increase with energy above 1014.5 eV and that the dominant component around the knee is not protons.

  13. High energy properties of the flat spectrum radio quasar 4C 50.11

    CERN Document Server

    Zhou, Jianeng; Liang, Chen; Wang, Zhongxiang

    2016-01-01

    We investigate the $\\gamma$-ray and X-ray properties of the flat spectrum radio quasar (FSRQ) \\4c50 at redshift $z= 1.517$. The {\\it Fermi} Large Area Telescope (LAT) data indicate that this source was in an active state since 2013 July. During the active period, the $\\gamma$-ray flux increased by more than a factor of three and two distinct flares were detected with the variability timescale as short as several hours. The $\\gamma$-ray spectra can be well fitted by a log-parabola. From the fitting, we find a correlation between the peak energy and spectral curvature for the $\\gamma$-ray spectra, which is the first time seen in $\\gamma$-ray emission from a blazar. The {\\it Swift} X-ray Telescope (XRT) data show that the source was variable at X-ray energies, but no evidence shows flux or spectral changes related to the $\\gamma$-ray activity. The broad-band X-ray spectrum obtained with {\\it Swift} XRT and {\\it NuSTAR} is well described by a broken PL model, with an extremely hard spectrum ($\\Gamma_{1} \\sim 0.1$...

  14. The Energy Spectrum of Ultra-High-Energy Cosmic Rays Measured by the Telescope Array FADC Fluorescence Detectors in Monocular Mode

    CERN Document Server

    Abu-Zayyad, T; Allen, M; Anderson, R; Azuma, R; Barcikowski, E; Belz, J W; Bergman, D R; Blake, S A; Cady, R; Cheon, B G; Chiba, J; Chikawa, M; Cho, E J; Cho, W R; Fujii, H; Fujii, T; Fukuda, T; Fukushima, M; Hanlon, W; Hayashi, K; Hayashi, Y; Hayashida, N; Hibino, K; Hiyama, K; Honda, K; Iguchi, T; Ikeda, D; Ikuta, K; Inoue, N; Ishii, T; Ishimori, R; Ito, H; Ivanov, D; Iwamoto, S; Jui, C C H; Kadota, K; Kakimoto, F; Kalashev, O; Kanbe, T; Kasahara, K; Kawai, H; Kawakami, S; Kawana, S; Kido, E; Kim, H B; Kim, H K; Kim, J H; Kitamoto, K; Kitamura, S; Kitamura, Y; Kobayashi, K; Kobayashi, Y; Kondo, Y; Kuramoto, K; Kuzmin, V; Kwon, Y J; Lan, J; Lim, S I; Lundquist, J P; Machida, S; Martens, K; Matsuda, T; Matsuura, T; Matsuyama, T; Matthews, J N; Myers, I; Minamino, M; Miyata, K; Murano, Y; Nagataki, S; Nakamura, T; Nam, S W; Nonaka, T; Ogio, S; Ogura, J; Ohnishi, M; Ohoka, H; Oki, K; Oku, D; Okuda, T; Ono, M; Oshima, A; Ozawa, S; Park, I H; Pshirkov, M S; Rodriguez, D C; Roh, S Y; Rubtsov, G; Ryu, D; Sagawa, H; Sakurai, N; Sampson, A L; Scott, L M; Shah, P D; Shibata, F; Shibata, T; Shimodaira, H; Shin, B K; Shin, J I; Shirahama, T; Smith, J D; Sokolsky, P; Sonley, T J; Springer, R W; Stokes, B T; Stratton, S R; Stroman, T A; Suzuki, S; Takahashi, Y; Takeda, M; Taketa, A; Takita, M; Tameda, Y; Tanaka, H; Tanaka, K; Tanaka, M; Thomas, S B; Thomson, G B; Tinyakov, P; Tkachev, I; Tokuno, H; Tomida, T; Troitsky, S; Tsunesada, Y; Tsutsumi, K; Tsuyuguchi, Y; Uchihori, Y; Udo, S; Ukai, H; Vasiloff, G; Wada, Y; Wong, T; Yamakawa, Y; Yamane, R; Yamaoka, H; Yamazaki, K; Yang, J; Yoneda, Y; Yoshida, S; Yoshii, H; Zollinger, R; Zundel, Z

    2013-01-01

    We present a measurement of the energy spectrum of ultra-high-energy cosmic rays performed by the Telescope Array experiment using monocular observations from its two new FADC-based fluorescence detectors. After a short description of the experiment, we describe the data analysis and event reconstruction procedures. Since the aperture of the experiment must be calculated by Monte Carlo simulation, we describe this calculation and the comparisons of simulated and real data used to verify the validity of the aperture calculation. Finally, we present the energy spectrum calculated from the merged monocular data sets of the two FADC-based detectors, and also the combination of this merged spectrum with an independent, previously published monocular spectrum measurement performed by Telescope Array's third fluorescence detector (Abu-Zayyad {\\it et al.}, {Astropart. Phys.} 39 (2012), 109). This combined spectrum corroborates the recently published Telescope Array surface detector spectrum (Abu-Zayyad {\\it et al.}, ...

  15. Effect of dark energy sound speed and equation of state on CDM power spectrum

    CERN Document Server

    Ansari, Rizwan Ul Haq

    2014-01-01

    We study the influence of equation of state $w$ and effective sound speed $c_e$ of the dark energy perturbations on the cold dark matter(CDM) power spectrum.We consider different cases of the equation of state and the effective sound speed, the cold dark matter power spectrum is found to be generically suppressed in these cases as compared to the $\\Lambda$CDM model. The suppression at different length scales depends on the value of $w$ and $c_e$, and the effect of different $w$ is profoundly seen at all length scales. The influence of sound speed is significantly seen only at the intermediate length scales and is negligible at scales very much larger and smaller than the Hubble scale.

  16. The energy spectrum of cosmic-ray electrons measured with H.E.S.S

    International Nuclear Information System (INIS)

    The spectrum of cosmic-ray electrons has so far been measured using balloon and satellite-based instruments. At TeV energies, however, the sensitivity of such instruments is very limited due to the low flux of electrons at very high energies and small detection areas of balloon/satellite based experiments. The very large collection area of ground-based imaging atmospheric Cherenkov telescopes gives them a substantial advantage over balloon/ satellite based instruments when detecting very-high-energy electrons (> 300 GeV). By analysing data taken by the High Energy Stereoscopic System (H.E.S.S.), this work extends the known electron spectrum up to 4 TeV - a range that is not accessible to direct measurements. However, in contrast to direct measurements, imaging atmospheric Cherenkov telescopes such as H.E.S.S. detect air showers that cosmic-ray electrons initiate in the atmosphere rather than the primary particle. Thus, the main challenge is to differentiate between air showers initiated by electrons and those initiated by the hadronic background. A new analysis technique was developed that determines the background with the support of the machine-learning algorithm Random Forest. It is shown that this analysis technique can also be applied in other areas such as the analysis of diffuse γ rays from the Galactic plane. (orig.)

  17. The energy spectrum of cosmic-ray electrons measured with H.E.S.S.

    Energy Technology Data Exchange (ETDEWEB)

    Egberts, Kathrin

    2009-03-30

    The spectrum of cosmic-ray electrons has so far been measured using balloon and satellite-based instruments. At TeV energies, however, the sensitivity of such instruments is very limited due to the low flux of electrons at very high energies and small detection areas of balloon/satellite based experiments. The very large collection area of ground-based imaging atmospheric Cherenkov telescopes gives them a substantial advantage over balloon/ satellite based instruments when detecting very-high-energy electrons (> 300 GeV). By analysing data taken by the High Energy Stereoscopic System (H.E.S.S.), this work extends the known electron spectrum up to 4 TeV - a range that is not accessible to direct measurements. However, in contrast to direct measurements, imaging atmospheric Cherenkov telescopes such as H.E.S.S. detect air showers that cosmic-ray electrons initiate in the atmosphere rather than the primary particle. Thus, the main challenge is to differentiate between air showers initiated by electrons and those initiated by the hadronic background. A new analysis technique was developed that determines the background with the support of the machine-learning algorithm Random Forest. It is shown that this analysis technique can also be applied in other areas such as the analysis of diffuse {gamma} rays from the Galactic plane. (orig.)

  18. Neutron field produced by 25 MeV deuteron on thick beryllium for radiobiological study; energy spectrum.

    Science.gov (United States)

    Takada, Masashi; Mihara, Erika; Sasaki, Michiya; Nakamura, Takashi; Honma, Toshihiko; Kono, Koji; Fujitaka, Kazunobu

    2004-01-01

    Biological data is necessary for estimation of protection from neutrons, but there is a lack of data on biological effects of neutrons for radiation protection. Radiological study on fast neutrons has been done at the National Institute of Radiological Sciences. An intense neutron source has been produced by 25 MeV deuterons on a thick beryllium target. The neutron energy spectrum, which is essential for neutron energy deposition calculation, was measured from thermal to maximum energy range by using an organic liquid scintillator and multi-sphere moderated 3He proportional counters. The spectrum of the gamma rays accompanying the neutron beam was measured simultaneously with the neutron spectrum using the organic liquid scintillator. The transmission by the shield of the spurious neutrons originating from the target was measured to be less than 1% by using the organic liquid scintillator placed behind the collimator. The measured neutron energy spectrum is useful in dose calculations for radiobiology studies.

  19. Evaluation of Kolmogorov - Smirnov Test and Energy Detector Techniques for Cooperative Spectrum Sensing in Real Channel Conditions

    Directory of Open Access Journals (Sweden)

    D. Lekomtcev

    2015-06-01

    Full Text Available The cognitive radio technology allows solving one of the main issues of current wireless communication technologies, namely a deficit of vacant spectrum. A dynamic spectrum access used in the cognitive radio networks (CRN gives an ability to access an unused spectrum in real time. Cooperative spectrum sensing is the most effective method for spectrum holes detecting. It combines sensing information of multiple cognitive radio users. In this paper, an experimental evaluation of spectrum sensing methods based on the Kolmogorov - Smirnov statistical test and Energy Detector using the Universal Software Radio Peripheral (USRP devices synchronized through a MIMO cable and with further processing in the GNU Radio and Matlab software are presented. Three hard decision fusion schemes are analyzed. Simulation comparison between these rules is presented via Receiver Operating Characteristic (ROC curves. The influence of real channel with interferences is compared in contrast to commonly assumed AWGN channel model of vacant channel noise.

  20. Classification of vibrational resonances in the energy spectrum of the formaldehyde molecule and Katz's branch points

    Science.gov (United States)

    Bykov, A. D.; Duchko, A. N.

    2016-05-01

    The Rayleigh-Schrödinger perturbation theory of high orders and the algebraic Padé-Hermite approximants are used to determine the singular points of a vibrational energy function of the formaldehyde molecule dependent on a complex perturbation parameter as on the argument. It is shown that the Fermi, Darling-Dennison, and other higher-order vibrational resonances are related to Katz's points—common branch points on the complex plane of the energy of two vibrational states. Analysis of Katz's points that connect different vibrational states allows one to reveal essential resonance perturbations, to introduce an additional classification for them, and to determine the polyad structure of an energy spectrum.

  1. Energy spectrum of iron nuclei measured inside the MIR space craft using CR-39 track detectors

    Energy Technology Data Exchange (ETDEWEB)

    Guenther, W.; Leugner, D.; Becker, E.; Flesch, F.; Heinrich, W.; Huentrup, G.; Reitz, G.; Roecher, H.; Streibel, T

    1999-06-01

    We have exposed stacks of CR-39 plastic nuclear track detectors inside the MIR space craft during the EUROMIR95 space mission for almost 6 months. Over this long period a large number of tracks of high LET events was accumulated in the detector foils. The etching and measuring conditions for this experiment were optimized to detect tracks of stopping iron nuclei. We found 185 stopping iron nuclei inside the stack and identified their trajectories through the material of the experiment. Based on the energy-range relation the energy at the surface of the stack was determined. These particles allow the determination of the low energy part of the spectrum of iron nuclei behind shielding material inside the MIR station.

  2. Energy spectrum of iron nuclei measured inside the MIR space craft using CR-39 track detectors.

    Science.gov (United States)

    Gunther, W; Leugner, D; Becker, E; Flesch, F; Heinrich, W; Huntrup, G; Reitz, G; Rocher, H; Streibel, T

    1999-06-01

    We have exposed stacks of CR-39 plastic nuclear track detectors inside the MIR space craft during the EUROMIR95 space mission for almost 6 months. Over this long period a large number of tracks of high LET events was accumulated in the detector foils. The etching and measuring conditions for this experiment were optimized to detect tracks of stopping iron nuclei. We found 185 stopping iron nuclei inside the stack and identified their trajectories through the material of the experiment. Based on the energy-range relation the energy at the surface of the stack was determined. These particles allow the determination of the low energy part of the spectrum of iron nuclei behind shielding material inside the MIR station.

  3. Energy spectrum of iron nuclei measured inside the MIR space craft using CR-39 track detectors

    CERN Document Server

    Guenther, W; Becker, E; Flesch, F; Heinrich, W; Huentrup, G; Reitz, G; Roecher, H; Streibel, T

    1999-01-01

    We have exposed stacks of CR-39 plastic nuclear track detectors inside the MIR space craft during the EUROMIR95 space mission for almost 6 months. Over this long period a large number of tracks of high LET events was accumulated in the detector foils. The etching and measuring conditions for this experiment were optimized to detect tracks of stopping iron nuclei. We found 185 stopping iron nuclei inside the stack and identified their trajectories through the material of the experiment. Based on the energy-range relation the energy at the surface of the stack was determined. These particles allow the determination of the low energy part of the spectrum of iron nuclei behind shielding material inside the MIR station.

  4. Molecular Structure, Vibrational Spectrum and Ionization Energy of m-Dimethoxybenzene

    Institute of Scientific and Technical Information of China (English)

    HUANG,Jian-Han; HUANG,Ke-Long; LIU,Su-Qin; LUO,Qiong

    2007-01-01

    The optimized molecular geometries of the three rotamers of m-dimethoxybenzene in the ground S0 and electronically excited S1 states were predicted by ab initio and density functional theory (DFT) calculations. Their vibrational spectra in the S1 state were studied by one color resonant two photon ionization (1C-R2PI) method, and their ionization energies were measured by two color resonant two photon ionization (2C-R2PI) experiment. The optimized molecular geometries showed that the total energy of conformer a was the lowest in the S0 state. Most of the active vibrations assigned from the 1C-R2PI spectrum were found to be of the in-plane ring modes. The ionization energies (IE) of conformers a, b and c were determined to be 63521, 64487 and 63755 cm-1, respectively.

  5. Characterization of optical anisotropy in quantum wells under compressive anisotropic in-plane strain

    Science.gov (United States)

    Biermann, Mark L.; Walters, Matthew; Diaz-Barriga, James; Rabinovich, W. S.

    2003-10-01

    Anisotropic in-plane strain in quantum wells leads to an optical polarization anisotropy that can be exploited for device applications. We have determined that for many anisotropic compressive strain cases, the dependence of the optical anisotropy is linear in the strain anisotropy. This result holds for a variety of well and barrier materials and widths and for various overall strain conditions. Further, the polarization anisotropy per strain anisotropy varies as the reciprocal of the energy separation of the relevant hole sub-bands. Hence, a general result for the polarization anisotropy per strain anisotropy is avialable for cases of compressive anisotropic in-plane strain.

  6. Characterization of optical anisotropy in quantum wells under compressive anisotropic in-plane strain

    Energy Technology Data Exchange (ETDEWEB)

    Biermann, Mark L [Physics Department, 566 Brownson Rd., U.S. Naval Academy, Annapolis, MD 21402 (United States); Walters, Matthew [Physics Department, 566 Brownson Rd., U.S. Naval Academy, Annapolis, MD 21402 (United States); Diaz-Barriga, James [Physics Department, 566 Brownson Rd., U.S. Naval Academy, Annapolis, MD 21402 (United States); Rabinovich, W S [Naval Research Laboratory, Code 5652, 4555 Overlook Ave. SW, Washington, DC 20375-5320 (United States)

    2003-10-21

    Anisotropic in-plane strain in quantum wells leads to an optical polarization anisotropy that can be exploited for device applications. We have determined that for many anisotropic compressive strain cases, the dependence of the optical anisotropy is linear in the strain anisotropy. This result holds for a variety of well and barrier materials and widths and for various overall strain conditions. Further, the polarization anisotropy per strain anisotropy varies as the reciprocal of the energy separation of the relevant hole sub-bands. Hence, a general result for the polarization anisotropy per strain anisotropy is available for cases of compressive anisotropic in-plane strain.

  7. The expected anisotropy in solid inflation

    Energy Technology Data Exchange (ETDEWEB)

    Bartolo, Nicola; Ricciardone, Angelo [Dipartimento di Fisica e Astronomia ' ' G. Galilei' ' , Università degli Studi di Padova, via Marzolo 8, I-35131, Padova (Italy); Peloso, Marco; Unal, Caner, E-mail: nicola.bartolo@pd.infn.it, E-mail: peloso@physics.umn.edu, E-mail: angelo.ricciardone@pd.infn.it, E-mail: unal@physics.umn.edu [School of Physics and Astronomy, University of Minnesota, 116 Church Street S.E., Minneapolis 55455 (United States)

    2014-11-01

    Solid inflation is an effective field theory of inflation in which isotropy and homogeneity are accomplished via a specific combination of anisotropic sources (three scalar fields that individually break isotropy). This results in specific observational signatures that are not found in standard models of inflation: a non-trivial angular dependence for the squeezed bispectrum, and a possibly long period of anisotropic inflation (to drive inflation, the ''solid'' must be very insensitive to any deformation, and thus background anisotropies are very slowly erased). In this paper we compute the expected level of statistical anisotropy in the power spectrum of the curvature perturbations of this model. To do so, we account for the classical background values of the three scalar fields that are generated on large (superhorizon) scales during inflation via a random walk sum, as the perturbation modes leave the horizon. Such an anisotropy is unavoidably generated, even starting from perfectly isotropic classical initial conditions. The expected level of anisotropy is related to the duration of inflation and to the amplitude of the squeezed bispectrum. If this amplitude is close to its current observational limit (so that one of the most interesting predictions of the model can be observed in the near future), we find that a level of statistical anisotropy F{sup 2} gives frozen and scale invariant vector perturbations on superhorizon scales.

  8. The expected anisotropy in solid inflation

    International Nuclear Information System (INIS)

    Solid inflation is an effective field theory of inflation in which isotropy and homogeneity are accomplished via a specific combination of anisotropic sources (three scalar fields that individually break isotropy). This results in specific observational signatures that are not found in standard models of inflation: a non-trivial angular dependence for the squeezed bispectrum, and a possibly long period of anisotropic inflation (to drive inflation, the ''solid'' must be very insensitive to any deformation, and thus background anisotropies are very slowly erased). In this paper we compute the expected level of statistical anisotropy in the power spectrum of the curvature perturbations of this model. To do so, we account for the classical background values of the three scalar fields that are generated on large (superhorizon) scales during inflation via a random walk sum, as the perturbation modes leave the horizon. Such an anisotropy is unavoidably generated, even starting from perfectly isotropic classical initial conditions. The expected level of anisotropy is related to the duration of inflation and to the amplitude of the squeezed bispectrum. If this amplitude is close to its current observational limit (so that one of the most interesting predictions of the model can be observed in the near future), we find that a level of statistical anisotropy F2 gives frozen and scale invariant vector perturbations on superhorizon scales

  9. Measurement of anisotropies in the large-scale diffuse gamma-ray emission

    CERN Document Server

    Vargas, German Gomez

    2010-01-01

    We have performed the first measurement of the angular power spectrum in the large-scale diffuse emission at energies from 1-50 GeV. We compared results from data and a simulated model in order to identify significant differences in anisotropy properties. We found angular power above the photon noise level in the data at multipoles greater than ~ 100 for energies 1< E <10 GeV. The excess power in the data suggests a contribution from a point source population not present in the model.

  10. Effects of synchrotron radiation spectrum energy on polymethyl methacrylate photosensitivity to deep x-ray lithography

    CERN Document Server

    Mekaru, H; Hattori, T

    2003-01-01

    Since X-ray lithography requires a high photon flux to achieve deep resist exposure, a synchrotron radiation beam, which is not monochromatized, is generally used as a light source. If the synchrotron radiation beam is monochromatized, photon flux will decrease rapidly. Because of this reason, the wavelength dependence of the resist sensitivity has not been investigated for deep X-ray lithography. Measuring the spectrum of a white beam with a Si solid-state detector (SSD) is difficult because a white beam has a high intensity and an SSD has a high sensitivity. We were able to measure the spectrum and the photocurrent of a white beam from a beam line used for deep X-ray lithography by keeping the ring current below 0.05 mA. We evaluated the characteristics of the output beam based on the measured spectrum and photocurrent, and used them to investigate the relationship between the total exposure energy and the dose-processing depth with polymethyl methacrylate (PMMA). We found that it is possible to guess the p...

  11. Vacuum and Gravitons of Relic Gravitational Waves, and Regularization of Spectrum and Energy-Momentum Tensor

    CERN Document Server

    Wang, Dong-Gang; Chen, Jie-Wen

    2015-01-01

    The spectrum of relic gravitational wave (RGW) contains high-frequency divergences, which should be removed. We present a systematic study of the issue, based on the exact RGW solution that covers the five stages, from inflation to the acceleration, each being a power law expansion. We show that the present RGW consists of vacuum dominating at $f>10^{11}$Hz and graviton dominating at $f<10^{11}$Hz, respectively. The gravitons are produced by the four cosmic transitions, mostly by the inflation-reheating one. We perform adiabatic regularization to remove vacuum divergences in three schemes: at present, at the end of inflation, and at horizon-exit, to the 2-nd adiabatic order for the spectrum, and the 4-th order for energy density and pressure. In the first scheme a cutoff is needed to remove graviton divergences. We find that all three schemes yield the spectra of a similar profile, and the primordial spectrum defined far outside horizon during inflation is practically unaffected. We also regularize the gau...

  12. Energy-Based Collaborative Spectrum Sensing for Cognitive UWB Impulse Radio

    Institute of Scientific and Technical Information of China (English)

    Wei-Chiang Wu; Chun-Te Wu

    2015-01-01

    This paper focuses on the issue of collaborative spectrum sensing in cognitive ultra wideband (CUWB) impulse radio. We employ energy-based signal detection method and apply the Neyman-Pearson (NP) decision rule to determine the optimum threshold. Two cooperative spectrum sensing schemes are developed in this paper. The decision fusion scheme is based on hard decision, in which each cooperating cognitive user (CU) sends its own local decision to the fusion center (FC). The FC then makes a final decision according to the majority voting rule. Alternatively, the data fusion scheme is based on soft decision, in which each local CU sends its observed value directly to the FC. The FC combines these values, compares to a threshold and then makes the final decision. The performances of both schemes are studied by using analytical tools and computer simulations. The receiver operating characteristics (ROC), which reveal the probability of detection versus false-alarm curve, are employed to evaluate the system performance under different scenarios.Simulation results demonstrate that the data fusion scheme outperforms the decision fusion scheme and verify that the collaborative spectrum sensing has practical importance in CUWB networks.

  13. Energy Spectrum of a Degenerate Fermi Gas at the BEC-BCS Crossover

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    A theoretical study of the BCS-BEC crossover is presented. Starting from a two-channel Boson-Fermion resonance model, the BCS-Bogoiubov mean-field method and the Green's function method are adopted. The result shows that we can end up with a BCS-type theory but with a composite order parameter. Calculation shows that the Bose condensate of BCS Cooper pairs is proportional to the molecular BEC of Bose molecules. The resonance superfluid phase is indicated by the energy spectrum with an obvious interpretation of the transition mechanism.

  14. Minimax determination of the energy spectrum of the Dirac equation in a Schwarzschild background

    OpenAIRE

    Caceres, Alejandro; Doran, Chris

    2005-01-01

    We calculate the bound-state energy spectrum of the Dirac Equation in a Schwarzschild black hole background using a minimax variational method. Our method extends that of Talman to the case of non-Hermitian interactions, such as a black hole. The trial function is expressed in terms of a basis set that takes into account both the Hermitian limit of the interaction in the non-relativistic approximation, and the general behaviour of the solutions at the origin, the horizon and infinity. Using t...

  15. Fractal energy spectrum of a polariton gas in a Fibonacci quasiperiodic potential.

    Science.gov (United States)

    Tanese, D; Gurevich, E; Baboux, F; Jacqmin, T; Lemaître, A; Galopin, E; Sagnes, I; Amo, A; Bloch, J; Akkermans, E

    2014-04-11

    We report on the study of a polariton gas confined in a quasiperiodic one-dimensional cavity, described by a Fibonacci sequence. Imaging the polariton modes both in real and reciprocal space, we observe features characteristic of their fractal energy spectrum such as the opening of minigaps obeying the gap labeling theorem and log-periodic oscillations of the integrated density of states. These observations are accurately reproduced solving an effective 1D Schrödinger equation, illustrating the potential of cavity polaritons as a quantum simulator in complex topological geometries. PMID:24765996

  16. Quantum control of isomerization by robust navigation in the energy spectrum

    Energy Technology Data Exchange (ETDEWEB)

    Murgida, G. E., E-mail: murgida@tandar.cnea.gov.ar [Centro Atómico Constituyentes, GIyA, CNEA, San Martín, and Consejo Nacional de Investigaciones Científicas y Técnicas, C1033AAJ Buenos Aires (Argentina); Arranz, F. J., E-mail: fj.arranz@upm.es [Grupo de Sistemas Complejos, Universidad Politécnica de Madrid, 28040 Madrid (Spain); Borondo, F., E-mail: f.borondo@uam.es [Departamento de Química, Universidad Autónoma de Madrid, Cantoblanco, 28049 Madrid (Spain); Instituto de Ciencias Matemáticas (ICMAT), Cantoblanco, 28049 Madrid (Spain)

    2015-12-07

    In this paper, we present a detailed study on the application of the quantum control technique of navigation in the energy spectrum to chemical isomerization processes, namely, CN–Li⇆ Li–CN. This technique is based on the controlled time variation of a Hamiltonian parameter, an external uniform electric field in our case. The main result of our work establishes that the navigation involved in the method is robust, in the sense that quite sizable deviations from a pre-established control parameter time profile can be introduced and still get good final results. This is specially relevant thinking of a experimental implementation of the method.

  17. Energy spectrum analysis between single and dual energy source x-ray imaging for PCB non-destructive test

    Energy Technology Data Exchange (ETDEWEB)

    Park, Kyeong Jin; Kim, Myung Soo; Lee, Min Ju; Kang, Dong Uk; Lee, Dae Hee; Kim, Ye Won; Kim, Chan Kyu; Kim, Hyoung Taek; Kim, Gi Yoon; Cho, Gyu Seong [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2015-08-15

    Reliability of printed circuit board (PCB), which is based on high integrated circuit technology, is having been important because of development of electric and self-driving car. In order to answer these demand, automated X-ray inspection (AXI) is best solution for PCB nondestructive test. PCB is consist of plastic, copper, and, lead, which have low to high Z-number materials. By using dual energy X-ray imaging, these materials can be inspected accurately and efficiently. Dual energy X-ray imaging, that have the advantage of separating materials, however, need some solution such as energy separation method and enhancing efficiency because PCB has materials that has wide range of Z-number. In this work, we found out several things by analysis of X-ray energy spectrum. Separating between lead and combination of plastic and copper is only possible with energy range not dose. On the other hand, separating between plastic and copper is only with dose not energy range. Moreover the copper filter of high energy part of dual X-ray imaging and 50 kVp of low energy part of dual X-ray imaging is best for efficiency.

  18. High energy emission from flat-spectrum radio sources with ˜ kpc-scale structure

    Science.gov (United States)

    Augusto, Pedro

    Active Galactic Nuclei emit a substantial portion of their bolometric luminosities in X-rays. For example, the knots in radio jets are prominent sources of synchrotron X-rays while the hotspots of the brightest FRIIs emit self-synchrotron or Inverse Compton radiation. Most high-energy studies on flat-spectrum radio sources have been conducted for blazars which are dominant at γ-rays.Augusto et al. (1998) have built a sample of 55 flat-spectrum radio sources dominated by structures (knots, hotspots, etc.) ˜0.1-2 kpc away from the nucleus. Seventeen (31%) of these are detected in X-rays (they tend to be the radio strongest) evenly splitting, morphologically, both at optical (radio) bands: nine QSO/BLLac (core-jets) on one-side; eight Galaxy/Sy2 (CSO/MSO/FRII) on the other. We have identified five confirmed compact/medium symmetric objects (CSO/MSOs) as X-ray emitters. A comparable type of source to CSO/MSOs is the physically similar (1-15 kpc) compact steep spectrum source (CSS), 28/129 (22%) of which are detected in X-rays, from a literature-selected sample (the percentage is smaller than for the 55-source sample due to a lower ). A 95% conf. level relation is found for CSSs: S_X ∝ (S4.85)0.6 and we found undistinguishable radio/X-ray properties for both the 55-source and CSS samples: clearly, their similar morphologies (e.g. knots in jets) stand up stronger than their radical radio spectrum differences.Only two sources among the 55 (4%) have γ-ray detections and they seem quite abnormal (in αxγ values, at least)-one of them is in a Sy2, not in a blazar.

  19. On Possible Interpretations of the High Energy Electron-Positron Spectrum Measured by the Fermi Large Area Telescope

    Energy Technology Data Exchange (ETDEWEB)

    Grasso, D.; Profumo, S.; Strong, A.W.; Baldini, L.; Bellazzini, R.; Bloom, E.D.; Bregeon, J.; Di Bernardo, G.; Gaggero, D.; Giglietto, N.; Kamae, T.; Latronico, L.; Longo, F.; Mazziotta, M.N.; Moiseev, A.A.; Morselli, A.; Ormes, J.F.; Pesce-Rollins, M.; Pohl, M.; Razzano, M.; Sgro, C.

    2009-05-15

    The Fermi-LAT experiment recently reported high precision measurements of the spectrum of cosmic-ray electrons-plus-positrons (CRE) between 20 GeV and 1 TeV. The spectrum shows no prominent spectral features, and is significantly harder than that inferred from several previous experiments. Here we discuss several interpretations of the Fermi results based either on a single large scale Galactic CRE component or by invoking additional electron-positron primary sources, e.g. nearby pulsars or particle Dark Matter annihilation. We show that while the reported Fermi-LAT data alone can be interpreted in terms of a single component scenario, when combined with other complementary experimental results, specifically the CRE spectrum measured by H.E.S.S. and especially the positron fraction reported by PAMELA between 1 and 100 GeV, that class of models fails to provide a consistent interpretation. Rather, we find that several combinations of parameters, involving both the pulsar and dark matter scenarios, allow a consistent description of those results. We also briefly discuss the possibility of discriminating between the pulsar and dark matter interpretations by looking for a possible anisotropy in the CRE flux.

  20. Anisotropies in the cosmic microwave background: Theory

    Energy Technology Data Exchange (ETDEWEB)

    Dodelson, S.

    1998-02-01

    Anisotropies in the Cosmic Microwave Background (CMB) contain a wealth of information about the past history of the universe and the present values of cosmological parameters. I online some of the theoretical advances of the last few years. In particular, I emphasize that for a wide class of cosmological models, theorists can accurately calculate the spectrum to better than a percent. The spectrum of anisotropies today is directly related to the pattern of inhomogeneities present at the time of recombination. This recognition leads to a powerful argument that will enable us to distinguish inflationary models from other models of structure formation. If the inflationary models turn out to be correct, the free parameters in these models will be determined to unprecedented accuracy by the upcoming satellite missions.

  1. Measurement of the energy spectrum of cosmic rays above 10{sup 18} eV using the Pierre Auger Observatory

    Energy Technology Data Exchange (ETDEWEB)

    Abraham, J. [National Technological University, Faculty Mendoza (CONICET/CNEA), Mendoza (Argentina); Abreu, P. [LIP and Instituto Superior Tecnico, Lisboa (Portugal); Aglietta, M. [Istituto di Fisica dello Spazio Interplanetario (INAF), Universita di Torino and Sezione INFN, Torino (Italy); Ahn, E.J. [Fermilab, Batavia, IL (United States); Allard, D. [Laboratoire AstroParticule et Cosmologie (APC), Universite Paris 7, CNRS-IN2P3, Paris (France); Allen, J. [New York University, New York, NY (United States); Alvarez-Muniz, J. [Universidad de Santiago de Compostela (Spain); Ambrosio, M. [Universita di Napoli ' Federico II' and Sezione INFN, Napoli (Italy); Anchordoqui, L. [University of Wisconsin, Milwaukee, WI (United States); Andringa, S. [LIP and Instituto Superior Tecnico, Lisboa (Portugal); Anticic, T. [Rudjer Boskovic Institute, 10000 Zagreb (Croatia); Anzalone, A. [Istituto di Astrofisica Spaziale e Fisica Cosmica di Palermo (INAF), Palermo (Italy); Aramo, C. [Universita di Napoli ' Federico II' and Sezione INFN, Napoli (Italy); Arganda, E. [Universidad Complutense de Madrid, Madrid (Spain); Arisaka, K. [University of California, Los Angeles, CA (United States); Arqueros, F. [Universidad Complutense de Madrid, Madrid (Spain); Asorey, H. [Centro Atomico Bariloche and Instituto Balseiro (CNEA-UNCuyo-CONICET), San Carlos de Bariloche (Argentina); Assis, P. [LIP and Instituto Superior Tecnico, Lisboa (Portugal); Aublin, J. [Laboratoire de Physique Nucleaire et de Hautes Energies (LPNHE), Universites Paris 6 et Paris 7, CNRS-IN2P3, Paris (France); Ave, M. [Karlsruhe Institute of Technology - Campus North - Institut fuer Kernphysik, Karlsruhe (Germany); University of Chicago, Enrico Fermi Institute, Chicago, IL (United States)

    2010-03-08

    We report a measurement of the flux of cosmic rays with unprecedented precision and statistics using the Pierre Auger Observatory. Based on fluorescence observations in coincidence with at least one surface detector we derive a spectrum for energies above 10{sup 18} eV. We also update the previously published energy spectrum obtained with the surface detector array. The two spectra are combined addressing the systematic uncertainties and, in particular, the influence of the energy resolution on the spectral shape. The spectrum can be described by a broken power law E{sup -g}amma with index gamma=3.3 below the ankle which is measured at log{sub 10}(E{sub ankle}/eV)=18.6. Above the ankle the spectrum is described by a power law with index 2.6 followed by a flux suppression, above about log{sub 10}(E/eV)=19.5, detected with high statistical significance.

  2. Primordial Statistical Anisotropies: The Effective Field Theory Approach

    CERN Document Server

    Abolhasani, Ali Akbar; Emami, Razieh; Firouzjahi, Hassan

    2015-01-01

    In this work we present the effective field theory of primordial statistical anisotropies generated during anisotropic inflation involving a background $U(1)$ gauge field. Besides the usual Goldstone boson associated with the breaking of time diffeomorphism we have two additional Goldstone bosons associated with the breaking of spatial diffeomorphisms. We further identify these two new Goldstone bosons with the expected two transverse degrees of the $U(1)$ gauge field fluctuations. Upon defining the appropriate unitary gauge, we present the most general quadratic action which respects the remnant symmetry in the unitary gauge. The interactions between various Goldstone bosons leads to statistical anisotropy in curvature perturbation power spectrum. Calculating the general results for power spectrum anisotropy, we recover the previously known results in specific models of anisotropic inflation. In addition, we present novel results for statistical anisotropy in models with non-trivial sound speed for inflaton ...

  3. Azimuthal anisotropy of jet quenching at LHC

    Indian Academy of Sciences (India)

    I P Lokhtin; S V Petrushanko; L I Sarycheva; A M Snigirev

    2003-05-01

    We analyze the azimuthal anisotropy of jet spectra due to energy loss of hard partons in quark–gluon plasma, created initially in nuclear overlap zone in collisions with non-zero impact parameter. The calculations are performed for semi-central Pb–Pb collisions at LHC energy.

  4. Cutoff in the TeV Energy Spectrum of Markarian 421 During Strong Flares in 2001

    CERN Document Server

    Krennrich, F; Bond, I H; Bradbury, S M; Buckley, J H; Carter-Lewis, D A; Catanese, M; Cui, W; Dunlea, S; Das, D; De la Calle-Perez, I; Fegan, D J; Fegan, S J; Finley, J P; Gaidos, J A; Gibbs, K; Gillanders, G H; Hall, T A; Hillas, A M; Holder, J; Horan, D; Jordan, M; Kertzman, M P; Kieda, D B; Kildea, J; Knapp, J; Kosack, K; Lang, M J; Le Bohec, S; McKernan, B; Moriarty, P; Müller, D; Ong, R; Pallassini, R; Petry, D; Quinn, J; Reay, N W; Reynolds, P T; Rose, H J; Sembroski, G H; Sidwell, R A; Stanton, N; Swordy, S P; Vasilev, V; Wakely, S P; Weekes, T C

    2001-01-01

    Exceptionally strong and long lasting flaring activity of the blazar Markarian 421 (Mrk 421) occurred between January and March 2001. Based on the excellent signal-to-noise ratio of the data we derive the energy spectrum between 260 GeV - 17 TeV with unprecedented statistical precision. The spectrum is not well described by a simple power law even with a curvature term. Instead the data can be described by a power law with exponential cutoff: $\\rm {{dN}\\over{dE}} \\propto \\rm E^{-2.14 \\pm 0.03_{stat}} \\times e^{-E/E_{0}} m^{-2} s^{-1} TeV^{-1}$ with $\\rm E_{0} = 4.3 \\pm 0.3_{stat} TeV$. Mrk 421 is the second $\\gamma$-ray blazar that unambiguously exhibits an absorption-like feature in its spectral energy distribution at 3-6 TeV suggesting that this may be a universal phenomenon, possibly due to the extragalactic infra-red background radiation.

  5. The Hybrid Energy Spectrum of TA's Middle Drum Detector and Surface Array

    CERN Document Server

    ,

    2014-01-01

    The Telescope Array experiment studies ultra high energy cosmic rays using a hybrid detector. Fluorescence telescopes measure the longitudinal development of the extensive air shower generated when a primary cosmic ray particle interacts with the atmosphere. Meanwhile, scintillator detectors measure the lateral distribution of secondary shower particles that hit the ground. The Middle Drum (MD) fluorescence telescope station consists of 14 telescopes from the High Resolution Fly's Eye (HiRes) experiment, providing a direct link back to the HiRes measurements. Using the scintillator detector data in conjunction with the telescope data improves the geometrical reconstruction of the showers significantly, and hence, provides a more accurate reconstruction of the energy of the primary particle. The Middle Drum hybrid spectrum is presented and compared to that measured by the Middle Drum station in monocular mode. Further, the hybrid data establishes a link between the Middle Drum data and the surface array. A com...

  6. Intensity and energy spectrum of electrons accelerated in the earth's bow shock

    Science.gov (United States)

    Anderson, K. A.

    1974-01-01

    Shock waves accelerate charged particles in the solar atmosphere, in interplanetary space and around the earth's magnetosphere. Acceleration of both electrons and protons occurs in the earth's bow-shock. The acceleration of protons up to 100 keV appears to be a steady state process and may even occur upstream from the bow shock due to waves generated by reflected solar wind protons. The electrons, on the other hand, are known to be accelerated in or near the shock. The intensity of these electrons ranges from about 100 to 2,000 per sr-sq cm-sec-keV at 14 keV. The energy spectrum is not a simple power low and is highly variable. If segments of the spectra are fitted to a power low, slopes ranging from -2 to -4.5 result over the energy range 0.5 to 100 keV.

  7. Exclusive Measurements of the b to s gamma Transition Rate and Photon Energy Spectrum

    Energy Technology Data Exchange (ETDEWEB)

    Lees, J.P.; Poireau, V.; Tisserand, V.; /Annecy, LAPP; Garra Tico, J.; Grauges, E.; /Barcelona U., ECM; Palano, A.; /Bari U. /INFN, Bari; Eigen, G.; Stugu, B.; /Bergen U.; Brown, David Nathan; Kerth, L.T.; Kolomensky, Yu.G.; Lynch, G.; /LBL, Berkeley /UC, Berkeley; Koch, H.; Schroeder, T.; /Ruhr U., Bochum; Asgeirsson, D.J.; Hearty, C.; Mattison, T.S.; McKenna, J.A.; /British Columbia U.; Khan, A.; /Brunel U.; Blinov, V.E.; Buzykaev, A.R.; /Novosibirsk, IYF /UC, Irvine /UC, Riverside /UC, Santa Barbara /UC, Santa Cruz /Caltech /Cincinnati U. /Colorado U. /Colorado State U. /Dortmund U. /Dresden, Tech. U. /Ecole Polytechnique /Edinburgh U. /Ferrara U. /INFN, Ferrara /Frascati /Genoa U. /INFN, Genoa /Indian Inst. Tech., Guwahati /Harvard U. /Harvey Mudd Coll. /Heidelberg U. /Humboldt U., Berlin /Imperial Coll., London /Iowa State U. /Iowa State U. /Johns Hopkins U. /Orsay, LAL /LLNL, Livermore /Liverpool U. /Queen Mary, U. of London /Royal Holloway, U. of London /Louisville U. /Mainz U., Inst. Kernphys. /Manchester U., Comp. Sci. Dept. /Maryland U. /Massachusetts U., Amherst /MIT /McGill U. /Milan U. /INFN, Milan /Mississippi U. /Montreal U. /Naples U. /INFN, Naples /NIKHEF, Amsterdam /Notre Dame U. /Ohio State U.; /more authors..

    2012-08-30

    We use 429 fb{sup -1} of e{sup +}e{sup -} collision data collected at the {Upsilon}(4S) resonance with the BABAR detector to measure the radiative transition rate of b {yields} s{gamma} with a sum of 38 exclusive final states. The inclusive branching fraction with a minimum photon energy of 1.9 GeV is found to be {Beta}({bar B} {yields} Xs{gamma}) = (3.29 {+-} 0.19 {+-} 0.48) x 10{sup -4} where the first uncertainty is statistical and the second is systematic. We also measure the first and second moments of the photon energy spectrum and extract the best fit values for the heavy-quark parameters, m{sub b} and {mu}{sub {pi}}{sup 2}, in the kinetic and shape function models.

  8. Application of Wavelet Packet Energy Spectrum to Extract the Feature of the Pulse Signal

    Institute of Scientific and Technical Information of China (English)

    Dian-guo CAO; Yu-qiang WU; Xue-wen SHI; Peng WANG

    2010-01-01

    The wavelet packet is presented as a new kind of multi-scale analysis technique followed by Wavelet analysis. The fundamental and realization arithmetic of the wavelet packet analysis method are described in this paper. A new application approach of the wavelet packed method to extract the feature of the pulse signal from energy distributing angle is expatiated. It is convenient for the microchip to process and judge by using the wavelet packet analysis method to make the pulse signals quantized and analyzed. Kinds of experiments are simulated in the lab, and the experiments prove that it is a convenient and accurate method to extract the feature of the pulse signal based on wavelet packed-energy spectrum analysis.

  9. The All Particle Cosmic-Ray Energy Spectrum Measured with HAWC

    Science.gov (United States)

    Hampel-Arias, Zigfried; HAWC Collaboration

    2016-03-01

    We present results of a measurement of the all-particle cosmic-ray energy spectrum above 10 TeV with the High-Altitude Water Cherenkov (HAWC) Observatory. HAWC is a ground based air shower array deployed on the slopes of Volcán Sierra Negra in the state of Puebla, México. It comprises 300 large light-tight water tanks covering an area of 20,000 square meters. Each tank is instrumented with four photomultipliers to detect particles from extensive air showers produced by gamma rays and cosmic rays upon entering the Earth's atmosphere. HAWC is optimized for the detection of gamma-ray induced air showers, yet the background flux of hadronic air showers is four orders of magnitude greater, allowing for a detailed study of the cosmic-ray flux in the TeV energy range. The primary cosmic-ray energy is determined with a maximum likelihood approach using the particle density as a function of distance to the shower core. Introducing quality cuts to isolate events with shower cores landing on the array, the reconstructed energy distribution is unfolded iteratively. We will report on the energy resolution of the technique and the results of the unfolding.

  10. Measuring the low-energy cosmic ray spectrum with the AFIS detector

    Energy Technology Data Exchange (ETDEWEB)

    Losekamm, Martin [Physics Department E18, Technische Universitaet Muenchen (Germany); Institute of Astronautics, Technische Universitaet Muenchen (Germany); Gaisbauer, Dominic; Greenwald, Daniel; Hahn, Alexander; Hauptmann, Philipp; Konorov, Igor; Meng, Lingxin; Paul, Stephan; Poeschl, Thomas [Physics Department E18, Technische Universitaet Muenchen (Germany); Renker, Dieter [Physics Department E17, Technische Universitaet Muenchen (Germany)

    2014-07-01

    High-energy cosmic rays interact with Earth's upper atmosphere and produce antiprotons, which can be trapped in Earth's magnetic field. The Antiproton Flux in Space (AFIS) Mission will measure the flux of trapped antiprotons with energies less than 100 MeV aboard the nanosatellite MOVE 2. An active-target tracking detector comprised of scintillating plastic fibers and silicon photomultipliers is already under construction at the Technische Universitaet Muenchen. As a precursor to the space-bound mission, a prototype version of the detector will be launched aboard a balloon from Kiruna, Sweden as part of the REXUS/BEXUS student program by the German Aerospace Center (DLR). Named AFIS-P, it will be used to measure the low-energy part of the cosmic-ray spectrum for energies less than 100 MeV-per-nucleon. Spectrometers in previous balloon missions were not sensitive in this low-energy region. Thus AFIS-P will deliver unprecedented data, while simultaneously allowing us to field-test the AFIS detector.

  11. The deep space galactic cosmic ray lineal energy spectrum at solar minimum

    Science.gov (United States)

    Case, A. W.; Kasper, J. C.; Spence, H. E.; Zeitlin, C. J.; Looper, M. D.; Golightly, M. J.; Schwadron, N. A.; Townsend, L. W.; Mazur, J. E.; Blake, J. B.; Iwata, Y.

    2013-06-01

    The Cosmic Ray Telescope for the Effects of Radiation (CRaTER) instrument is an energetic particle telescope on board the Lunar Reconnaissance Orbiter spacecraft. CRaTER measures energetic charged particles that have sufficient energy to penetrate the outer shielding of the instrument (about 12 MeV/nucleon). Galactic cosmic rays (GCR) with these energies are the primary radiation concern for spacecraft and astronauts outside of the Earth's magnetosphere during times of minimal solar activity. These particles can easily penetrate typical shielding and damage electronics, causing increased electronics failure rates and single event upsets. When this radiation impacts biological cells, it causes an increased risk of cancer. The CRaTER instrument was built to characterize the radiation dose and lineal energy with unprecedented time and energy resolution and was fortuitously flown during a period of time that coincided with the highest GCR fluxes in the modern space age. We report here this worst-case GCR lineal energy spectrum. Observations are made behind a thin aluminum window and different thicknesses of tissue-equivalent plastic. These measurements provide important observational data points to compare with current model predictions of the dose deposited by energetic particles within a tissue-like material.

  12. Full-Sky Analysis of Cosmic-Ray Anisotropy with IceCube and HAWC

    CERN Document Server

    ,

    2015-01-01

    During the past two decades, experiments in both the Northern and Southern hemispheres have observed a small but measurable energy-dependent sidereal anisotropy in the arrival direction distribution of galactic cosmic rays. The relative amplitude of the anisotropy is $10^{-4} - 10^{-3}$. However, each of these individual measurements is restricted by limited sky coverage, and so the pseudo-power spectrum of the anisotropy obtained from any one measurement displays a systematic correlation between different multipole modes $C_\\ell$. To address this issue, we present the preliminary status of a joint analysis of the anisotropy on all angular scales using cosmic-ray data from the IceCube Neutrino Observatory located at the South Pole ($90^\\circ$ S) and the High-Altitude Water Cherenkov (HAWC) Observatory located at Sierra Negra, Mexico ($19^\\circ$ N). We describe the methods used to combine the IceCube and HAWC data, address the individual detector systematics and study the region of overlapping field of view be...

  13. Energy spectrum and mass composition of primary cosmic radiation in the region above the knee from the GAMMA experiment

    CERN Document Server

    Martirosov, R M; Vardanyan, H S; Erlykin, A D; Nikolskaya, N M; Gallant, Y A; Jones, L W; Babayan, H A

    2012-01-01

    The energy spectrum of the primary cosmic radiation in the energy range 1 - 100 PeV and the extensive air shower (EAS) characteristics obtained on the basis of the expanded data bank of the GAMMA experiment (Mt. Aragats, Armenia) are presented. With increased statistics we confirm our previous results on the energy spectrum. The spectral index above the knee is about -3.1, but at energies beyond 20 PeV a flattening of the spectrum is observed. The existence of the 'bump' at about 70 PeV is confirmed with a significance of more than 4{\\sigma}. In the energy range of 10 - 100 PeV the shower age becomes energy independent and we observe a direct proportionality of the EAS size to the primary energy. This suggests an approximately constant depth of the EAS maximum in this energy range. This is evidence in favour of an increasing average mass of primary particles at energies above 20 PeV. The additional source scenario, which is a possible explanation of the 'bump' in the spectrum, also leads to the conclusion of ...

  14. Research on the Application of the Light-Energy Spectrum Fusion Technique to Land and Resources Survey

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    This paper introduces how to use remote sensing images including Landsat (MSS and TM) and airborne radioactivity images to identify the type of rocks in the areas covered by vegetation. The relationship between light spectrum (Landsat MSS and TM) and energy spectrum (U, Th and K) is discussed on the basis of correlation analysis, and it is proven that there are correlations between the Landsat MSS or TM data and the U, Th and K data. By using the fusion technique, new images were generated, which contain both the light spectrum and the energy spectrum information.Taking the Lucong basin as the study area, the present paper demonstrates the successful identification of various types of rocks using the fusion technique. Different types of rocks are represented by different colours on the new light-energy spectrum images, so that volcanic rocks of the Jurassic and Cretaceous periods can be discriminated. Another example, in the Lingquan basin in Northeast China, not only the different types of rocks are successfully distinguished, but corrections and modifications are also made on the original geological map after some field investigation. Practice has proven that the light-energy spectrum fusion technique is a good way in lithologic identification.

  15. Anisotropies of Gravitational Wave Backgrounds: A Line Of Sight Approach

    CERN Document Server

    Contaldi, Carlo R

    2016-01-01

    In the weak field regime, gravitational waves can be considered as being made up of collisionless, relativistic tensor modes that travel along null geodesics of the perturbed background metric. We work in this geometric optics picture to calculate the anisotropies in gravitational wave backgrounds resulting from astrophysical and cosmological sources. Our formalism yields expressions for the angular power spectrum of the anisotropies. We show how the anisotropies are sourced by intrinsic, Doppler, Sachs-Wolfe, and Integrated Sachs-Wolfe terms in analogy with Cosmic Microwave Background photons.

  16. Influence of boron diffusion on the perpendicular magnetic anisotropy in Ta|CoFeB|MgO ultrathin films

    Energy Technology Data Exchange (ETDEWEB)

    Sinha, Jaivardhan; Gruber, Maria; Kodzuka, Masaya; Ohkubo, Tadakatsu; Mitani, Seiji; Hono, Kazuhiro; Hayashi, Masamitsu, E-mail: hayashi.masamitsu@nims.go.jp [National Institute for Materials Science, Tsukuba 305-0047 (Japan)

    2015-01-28

    We have studied structural and magnetic properties of Ta|CoFeB|MgO heterostructures using cross-section transmission electron microscopy (TEM), electron energy loss spectrum (EELS) imaging, and vibrating sample magnetometry. From the TEM studies, the CoFeB layer is found to be predominantly amorphous for as deposited films, whereas small crystallites, diameter of ∼5 nm, are observed in films annealed at 300 °C. We find that the presence of such nanocrystallites is not sufficient for the occurrence of perpendicular magnetic anisotropy. Using EELS, we find that boron diffuses into the Ta underlayer upon annealing. The Ta underlayer thickness dependence of the magnetic anisotropy indicates that ∼0.2 nm of Ta underlayer is enough to absorb the boron from the CoFeB layer and induce perpendicular magnetic anisotropy. Boron diffusion upon annealing becomes limited when the CoFeB layer thickness is larger than ∼2 nm, which coincides with the thickness at which the saturation magnetization M{sub S} and the interface magnetic anisotropy K{sub I} drop by ∼20%. These results show the direct role which boron plays in determining the perpendicular magnetic anisotropy in CoFeB|MgO heterostructures.

  17. Threshold conditions, energy spectrum and bands generated by locally periodic Dirac comb potentials

    Science.gov (United States)

    Dharani, M.; Shastry, C. S.

    2016-01-01

    We derive expressions for polynomials governing the threshold conditions for different types of locally periodic Dirac comb potentials comprising of attractive and combination of attractive and repulsive delta potential terms confined symmetrically inside a one dimensional box of fixed length. The roots of these polynomials specify the conditions on the potential parameters in order to generate threshold energy bound states. The mathematical and numerical methods used by us were first formulated in our earlier works and it is also very briefly summarized in this paper. We report a number of mathematical results pertaining to the threshold conditions and these are useful in controlling the number of negative energy states as desired. We further demonstrate the correlation between the distribution of roots of these polynomials and negative energy eigenvalues. Using these results as basis, we investigate the energy bands in the positive energy spectrum for the above specified Dirac comb potentials and also for the corresponding repulsive case. In the case of attractive Dirac comb the base energy of the each band excluding the first band coincides with specific eigenvalue of the confining box whereas in the repulsive case it coincides with the band top. We deduce systematic correlation between band gaps, band spreads and box eigenvalues and explain the physical reason for the vanishing of band pattern at higher energies. In the case of Dirac comb comprising of orderly arranged attractive and repulsive delta potentials, specific box eigenvalues occur in the middle of each band excluding the first band. From our study we find that by controlling the number and strength parameters of delta terms in the Dirac comb and the size of confining box it is possible to generate desired types of band formations. We believe the results from our systematic analysis are useful and relevant in the study of various one dimensional systems of physical interest in areas like nanoscience.

  18. Constructing ab initio and empirical potential energy surfaces for water Infrared spectrum; Vibrational and rotational energy levels; Born- Oppenheimer surface

    CERN Document Server

    Kain, J S

    2001-01-01

    The infrared spectrum of water is possibly one of the most well studied and yet portions of it are still poorly understood. Recently, significant advances have been made in assigning water spectra using variational nuclear calculations. The major factor determining the accuracy of ro-vibrational spectra of water is the accuracy of the underlying Potential Energy Surface. Even the most accurate ab initio Potential Energy Surface does not reproduce the Born-Oppenheimer surface to sufficient accuracy for spectroscopic studies. Furthermore, effects beyond this model such as the adiabatic correction, the relativistic correction and the non-adiabatic correction have to be considered. This thesis includes a discussion on how the relativistic correction was calculated, for the water molecule, from first-order perturbation theory. The relativistic correction improved vibrational stretching motion while making the prediction of the bending modes far worse. For rotational motion the relativistic effect had an increasing...

  19. Observation of the Ankle and Evidence for a High-Energy Break in the Cosmic Ray Spectrum

    CERN Document Server

    Abbasi, R U; Amman, J F; Archbold, G; Atkins, R; Bellido, J A; Belov, K; Belz, J W; Ben-Zvi, S Y; Bergman, D R; Burt, G W; Cao, Z; Clay, R W; Connolly, B C; Deng, W; Dawson, B R; Fedorova, Y; Findlay, J; Finley, C B; Hanlon, W F; Hoffman, C M; Hughes, G A; Holzscheiter, M H; Hüntemeyer, P; Jui, C C H; Kim, K; Kirn, M A; Loh, E C; Maestas, M M; Manago, N; Marek, L J; Martens, K; Matthews, J A J; Matthews, J N; O'Neill, A; Painter, C A; Perera, L P; Reil, K; Riehle, R; Roberts, M; Sasaki, M; Schnetzer, S R; Simpson, K M; Sinnis, G; Smith, J D; Snow, R; Sokolsky, P; Song, C; Springer, R W; Stokes, B T; Thomas, J R; Thomas, S B; Thomson, G B; Tupa, D; Westerhoff, S; Wiencke, L R; Zech, A

    2005-01-01

    We have measured the cosmic ray spectrum at energies above $10^{17}$ eV using the two air fluorescence detectors of the High Resolution Fly's Eye experiment operating in monocular mode. We describe the detector, PMT and atmospheric calibrations, and the analysis techniques for the two detectors. We fit the spectrum to models describing galactic and extragalactic sources. Our measured spectrum gives an observation of a feature known as the ``ankle'' near $3\\times 10^{18}$ eV, and strong evidence for a suppression near $6\\times 10^{19}$ eV.

  20. Novel characteristics of energy spectrum for 3D Dirac oscillator analyzed via Lorentz covariant deformed algebra.

    Science.gov (United States)

    Betrouche, Malika; Maamache, Mustapha; Choi, Jeong Ryeol

    2013-11-14

    We investigate the Lorentz-covariant deformed algebra for Dirac oscillator problem, which is a generalization of Kempf deformed algebra in 3 + 1 dimension of space-time, where Lorentz symmetry are preserved. The energy spectrum of the system is analyzed by taking advantage of the corresponding wave functions with explicit spin state. We obtained entirely new results from our development based on Kempf algebra in comparison to the studies carried out with the non-Lorentz-covariant deformed one. A novel result of this research is that the quantized relativistic energy of the system in the presence of minimal length cannot grow indefinitely as quantum number n increases, but converges to a finite value, where c is the speed of light and β is a parameter that determines the scale of noncommutativity in space. If we consider the fact that the energy levels of ordinary oscillator is equally spaced, which leads to monotonic growth of quantized energy with the increment of n, this result is very interesting. The physical meaning of this consequence is discussed in detail.

  1. Are protons still dominant at the knee of the cosmic-ray energy spectrum?

    CERN Document Server

    Amenomori, M; Chen, D; Cui, S W; Danzengluobu; Ding, L K; Ding, X H; Feng Cun Feng; Feng, Z Y; Gao, X Y; Geng, Q X; Guo, H W; He, H H; He, M; Hibino, K; Hotta, N; Hu, H; Hu, H B; Huang, J; Huang, Q; Jia, H Y; Kajino, F; Kasahara, K; Katayose, Y; Kato, C; Kawata, K; Labaciren; Le, G M; Li, J Y; Lü, H; Lu, S L; Meng, X R; Mizutani, K; Mu, J; Munakata, K; Nagai, A; Nanjo, H; Nishizawa, M; Ohnishi, M; Ohta, I; Onuma, H; Ouchi, T; Ozawa, S; Ren, J R; Saitô, T; Sakata, M; Sasaki, T; Shibata, M; Shiomi, A; Shirai, T; Sugimoto, H; Takita, M; Tan, Y H; Tateyama, N; Torii, S; Tsuchiya, H; Udo, S; Wang, H; Wang, X; Wang, Y G; Wu, H R; Xue Liang; Yamamoto, Y; Yan, C T; Yang, X C; Yasue, S; Ye, Z H; Yu, G C; Yuan, A F; Yuda, T; Zhang, H M; Zhang, J L; Zhang, N J; Zhang, X Y; Zhang, Y; Zhang, Yi; Zhaxi Sang Zhu; Zhou, X X

    2006-01-01

    A hybrid experiment consisting of emulsion chambers, burst detectors and the Tibet II air-shower array was carried out at Yangbajing (4,300 m a.s.l., 606 g/cm$^2$) in Tibet to obtain the energy spectra of primary protons and heliums. From three-year operation, these energy spectra are deduced between $10^{15}$ and $10^{16}$ eV by triggering the air showers associated with a high energy core and using a neural network method in the primary mass separation. The proton spectrum can be expressed by a single power-law function with a differential index of $-3.01 \\pm 0.11$ and $-3.05 \\pm 0.12$ based on the QGSJET+HD and SIBYLL+HD models, respectively, which are steeper than that extrapolated from the direct observations of $-2.74 \\pm 0.01$ in the energy range below $10^{14}$ eV. The absolute fluxes of protons and heliums are derived within 30% systematic errors depending on the hadronic interaction models used in Monte Carlo simulation. The result of our experiment suggests that the main component responsible for t...

  2. Measurement of the Cosmic Ray Energy Spectrum with ARGO-YBJ

    CERN Document Server

    ,

    2014-01-01

    The ARGO-YBJ detector, located at high altitude in the Cosmic Ray Observatory of Yangbajing in Tibet (4300 m asl, about 600 g/cm2 of atmospheric depth) provides the opportunity to study, with unprecedented resolution, the cosmic ray physics in the primary energy region between 10^{12} and 10^{16} eV. The preliminary results of the measurement of all-particle and light-component (i.e. protons and helium) energy spectra between approximately 5 TeV and 5 PeV are reported and discussed. The study of such energy region is particularly interesting because not only it allows a better understanding of the so called 'knee' of the energy spectrum and of its origin, but also provides a powerful cross-check among very different experimental techniques. The comparison between direct measurements by balloons/satellites and the results by surface detectors, implying the knowledge of shower development in the atmosphere, also allows to test the hadronic interaction models currently used for understanding particle and cosmic ...

  3. SPECTRUM - a computer algorithm to derive the flux-energy spectrum of precipitating particles from EISCAT electron density profiles

    International Nuclear Information System (INIS)

    Three major improvements are included. First the new algorithm includes the time rate of change of ionisation. This can be measured on a time scale of a few seconds with the EISCAT radar during auroral precipitation. Second, the fixed energies of the incident electron beams assumed in the UNTANGLE program are replaced by energies which are calculated according to the altitudes at which measurements are made. Thus the energy resolution and energy interval included in the derived spectra are determined in a physically reasonable way by the altitude resolution and the altitude interval of the electron density measurements. Third, the equations relating the incident fluxes at each energy to the electron density at each altitude are written in matrix form which allows them to be solved using standard numerical algorithms. A possibility to fit proton fluxes rather than electron fluxes is also included. A companion program (PROFILE) which calculates ionisation rate or equilibrium electron density profiles for user-defined monoenergetic or Maxwellian particle precipitation has also been developed. (author)

  4. Correlation between peak energy and Fourier power density spectrum slope in gamma-ray bursts

    CERN Document Server

    Dichiara, S; Amati, L; Frontera, F; Margutti, R

    2016-01-01

    The origin of the gamma-ray burst (GRB) prompt emission still defies explanation, in spite of recent progress made, for example, on the occasional presence of a thermal component in the spectrum along with the ubiquitous non-thermal component that is modelled with a Band function. The combination of finite duration and aperiodic modulations make GRBs hard to characterise temporally. Although correlations between GRB luminosity and spectral hardness on one side and time variability on the other side have long been known, the loose and often arbitrary definition of the latter makes the interpretation uncertain. We characterise the temporal variability in an objective way and search for a connection with rest-frame spectral properties for a number of well-observed GRBs. We studied the individual power density spectra (PDS) of 123 long gamma-ray bursts with measured redshift, rest-frame peak energy Ep,i of the time-averaged nuFnu spectrum, and well-constrained PDS slope alpha detected with Swift, Fermi and past s...

  5. Collective behaviour of linear perturbation waves observed through the energy density spectrum

    Energy Technology Data Exchange (ETDEWEB)

    Scarsoglio, S [Department of Water Engineering, Politecnico di Torino (Italy); De Santi, F; Tordella, D, E-mail: stefania.scarsoglio@polito.it [Department of Aeronautics and Space Engineering, Politecnico di Torino (Italy)

    2011-12-22

    We consider the collective behaviour of small three-dimensional transient perturbations in sheared flows. In particular, we observe their varied life history through the temporal evolution of the amplification factor. The spectrum of wave vectors considered fills the range from the size of the external flow scale to the size of the very short dissipative waves. We observe that the amplification factor distribution is scale-invariant. In the condition we analyze, the system is subject to all the physical processes included in the linearized Navier-Stokes equations. With the exception of the nonlinear interaction, these features are the same as those characterizing the turbulent state. The linearized perturbative system offers a great variety of different transient behaviours associated to the parameter combination present in the initial conditions. For the energy spectrum computed by freezing each wave at the instant where its asymptotic condition is met, we ask whether this system is able to show a power-law scaling analogous to the Kolmogorov argument. At the moment, for at least two typical shear flows, the bluff-body wake and the plane Poiseuille flow, the answer is yes.

  6. Energy spectrum of secondary protons above the atmosphere measured by the instruments NINA and NINA-2

    Science.gov (United States)

    Bidoli, V.; Casolino, M.; de Pascale, M.; Furano, G.; Iannucci, A.; Morselli, A.; Picozza, P.; Sparvoli, R.; Bakaldin, A.; Galper, A.; Koldashov, S.; Korotkov, M.; Leonov, A.; Mikhailov, V.; Voronov, S.; Boezio, M.; Bonvicini, V.; Vacchi, A.; Zampa, G.; Zampa, N.; Ambriola, M.; Cafagna, F.; Circella, M.; de Marzo, C.; Adriani, O.; Papini, P.; Spillantini, P.; Straulino, S.; Vannuccini, E.; Ricci, M.; Castellini, G.

    2002-10-01

    In this paper we report on the energy spectrum of protons of albedo origin measured by the instruments NINA and NINA-2 at different geomagnetic locations, and the behaviour of the proton flux as a function of altitude out of the South Atlantic Anomaly. The instrument NINA was used on board the satellite Resurs-01-N4 between 1998 and 1999, at an altitude of about 830 km. The NINA-2 apparatus, on board the satellite MITA, was put into orbit in July 2000, at an altitude of about 450 km. A detailed understanding of the fluxes of charged particles in near Earth orbit is important to reach an accurate theoretical description of the Earth’s magnetic field, but also as input for the calculation of the back-ground for scientific instruments aboard satellites, like the future AGILE and GLAST g

  7. Cross-Spectrum PM Noise Measurements, Thermal Energy and Metamaterial Filters

    CERN Document Server

    Gruson, Yannick; Rohde, Ulrich L; Poddar, Ajay K; Rubiola, Enrico

    2016-01-01

    Virtually all commercial instruments for the measurement of the oscillator PM noise make use of the Cross Spectrum method (arXiv:1004.5539 [physics.ins-det], 2010). High sensitivity is achieved by correlation and averaging on two equal channels which measure the same input, and reject the background of the instrument. We show that a systematic error is always present if the thermal energy of the input power splitter is not accounted for. Such error can result in noise under estimation up to a few dB in the lowest-noise quartz oscillators, and in a complete nonsense in the case of cryogenic oscillators. As another alarming fact, the presence of metamaterial components in the oscillator results in unpredictable behavior and large errors, even in well controlled experimental conditions. We observed a spread of 40 dB in the phase noise spectra of an oscillator, just replacing the output filter.

  8. The energy spectrum observed by the AGASA experiment and the spatial distribution of the sources of ultra-high energy cosmic rays

    CERN Document Server

    Medina-Tanco, G A

    1999-01-01

    Seven and a half years of continuous monitoring of giant air showers triggered by ultra high-energy cosmic rays have been recently summarized by the AGASA collaboration. The resulting energy spectrum indicates clearly that the cosmic ray spectrum extends well beyond the Greisen-Zatsepin-Kuzmin (GZK) cut-off at $\\sim 5 \\times 10^{19}$ eV. Furthermore, despite the small number statistics involved, some structure in the spectrum may be emerging. Using numerical simulations, it is demonstrated in the present work that these features are consistent with a spatial distribution of sources that follows the distribution of luminous matter in the local Universe. Therefore, from this point of view, there is no need for a second high-energy component of cosmic rays dominating the spectrum beyond the GZK cut-off.

  9. On the energy spectrum of the hydrogen atom in a photon field. I

    International Nuclear Information System (INIS)

    In 1930 Weisskopf and Wigner gave an account, based on the Maxwell endash Schroedinger equations, of the natural spectral line broadening of radiation emitted by a hydrogen atom. Their calculations were based on an approximation involving certain single-photon transitions in the perturbation series for the solutions of these equations. In Part I of this series of papers the exact expressions for both the line shift and the line broadening are obtained from the Maxwell endash Dirac equations in such a way that the Weisskopf endash Wigner results appear as a second order approximation. The Maxwell endash Dirac Hamiltonian for the coupled fields is first shown to admit a complex analytic dilation in the energy variables. The Fredholm endash Born series for the resolvent is shown to converge uniformly when certain high-energy cutoff factors are included in the interaction and the photons are given a small mass. The series is then rearranged to show that the spectrum of the modified dilated Hamiltonian, which consists of a complete set of complex eigenvalues, thresholds, and branch cuts, is only a slight perturbation of the known spectrum of the dilated Hamiltonian for the uncoupled fields. The real part of the shift of each complex eigenvalue then accounts for the spectral line shift, and the complex part accounts for the associated line broadening. Finally, the implications for the scattering matrix and the various phenomena of resonance scattering are discussed. In Part II of this series these results are shown to remain valid when the cutoff factors and the photon mass are removed. copyright 1998 American Institute of Physics

  10. Measurements of cosmic ray anisotropies from Pioneers 10 and 11

    International Nuclear Information System (INIS)

    Cosmic ray anisotropy measurements are performed by the University of California, San Diego experiments on Pioneers 10 and 11. A directional Cerenkov counter sensitive to protons and α particles with kinetic energies >= 480 MeV/nucleon is used to determine east-west and north-south anisotropies. (orig./WBU)

  11. Effects of primary recoil (PKA) energy spectrum on radiation damage in fcc metals

    Energy Technology Data Exchange (ETDEWEB)

    Iwata, Tadao; Iwase, Akihiro [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

    1997-10-01

    Irradiation effects by different energetic particles such as electrons, various ions and neutrons are compared in fcc metals, particularly in Cu and Ni. It is discussed on the statistical consideration that the logarithm of the so-called PKA median energy, log T{sub 1/2}, is a good representative to characterize the primary recoil (i.e. PKA) energy spectrum with the resultant defect production. For the irradiations of electrons, various ions and neutrons to Cu and Ni, fundamental physical quantities such as the fraction of stage I recovery, the defect production cross sections and the radiation annealing cross sections can be well scaled as a function of log T{sub 1/2}, if the effects of the electron excitation caused by irradiating ions are excluded. Namely, all data of the respective physical quantity lie on a single continuous curve as a function of log T{sub 1/2}. This characteristic curve is utilized to predict the damage accumulation (i.e. defect concentration) as a function of dpa in Cu and Ni with the PKA median energy as a parameter. (author)

  12. Measurement of the Crab Nebula spectrum over three decades in energy with the MAGIC telescopes

    CERN Document Server

    Aleksić, J; Antonelli, L A; Antoranz, P; Babic, A; Bangale, P; Barrio, J A; González, J Becerra; Bednarek, W; Bernardini, E; Biasuzzi, B; Biland, A; Blanch, O; Bonnefoy, S; Bonnoli, G; Borracci, F; Bretz, T; Carmona, E; Carosi, A; Colin, P; Colombo, E; Contreras, J L; Cortina, J; Covino, S; Da Vela, P; Dazzi, F; De Angelis, A; De Caneva, G; De Lotto, B; Wilhelmi, E de Oña; Mendez, C Delgado; Prester, D Dominis; Dorner, D; Doro, M; Einecke, S; Eisenacher, D; Elsaesser, D; Fidalgo, D; Fonseca, M V; Font, L; Frantzen, K; Fruck, C; Galindo, D; López, R J García; Garczarczyk, M; Terrats, D Garrido; Gaug, M; Godinović, N; Muñoz, A González; Gozzini, S R; Hadasch, D; Hanabata, Y; Hayashida, M; Herrera, J; Hildebrand, D; Hose, J; Hrupec, D; Idec, W; Kadenius, V; Kellermann, H; Knoetig, M L; Kodani, K; Konno, Y; Krause, J; Kubo, H; Kushida, J; La Barbera, A; Lelas, D; Lewandowska, N; Lindfors, E; Lombardi, S; Longo, F; López, M; López-Coto, R; López-Oramas, A; Lorenz, E; Lozano, I; Makariev, M; Mallot, K; Maneva, G; Mankuzhiyil, N; Mannheim, K; Maraschi, L; Marcote, B; Mariotti, M; Martínez, M; Mazin, D; Menzel, U; Miranda, J M; Mirzoyan, R; Moralejo, A; Munar-Adrover, P; Nakajima, D; Neustroev, V; Niedzwiecki, A; Nilsson, K; Nishijima, K; Noda, K; Orito, R; Overkemping, A; Paiano, S; Palatiello, M; Paneque, D; Paoletti, R; Paredes, J M; Paredes-Fortuny, X; Persic, M; Poutanen, J; Moroni, P G Prada; Prandini, E; Puljak, I; Reinthal, R; Rhode, W; Ribó, M; Rico, J; Garcia, J Rodriguez; Rügamer, S; Saito, T; Saito, K; Satalecka, K; Scalzotto, V; Scapin, V; Schultz, C; Schweizer, T; Shore, S N; Sillanpää, A; Sitarek, J; Snidaric, I; Sobczynska, D; Spanier, F; Stamerra, A; Steinbring, T; Storz, J; Strzys, M; Takalo, L; Takami, H; Tavecchio, F; Temnikov, P; Terzić, T; Tescaro, D; Teshima, M; Thaele, J; Tibolla, O; Torres, D F; Toyama, T; Treves, A; Vogler, P; Will, M; Zanin, R

    2014-01-01

    The MAGIC stereoscopic system collected 69 hours of Crab Nebula data between October 2009 and April 2011. Analysis of this data sample using the latest improvements in the MAGIC stereoscopic software provided an unprecedented precision of spectral and night-by-night light curve determination at gamma rays. We derived a differential spectrum with a single instrument from 50 GeV up to almost 30 TeV with 5 bins per energy decade. In the low energies, MAGIC results, combined with the Fermi-LAT data, show a flat Inverse Compton peak. The Fermi-LAT and MAGIC spectral data were fit from 1 GeV to 30 TeV with a log-parabola, yielding a peak position at (53 $\\pm$ 3) GeV with a $\\chi^2_{red}$ = 82/27 (error probably underestimated due to the bad fit quality), showing that the log-parabola is not a good representation of the Inverse Compton peak of the Crab Nebula. There is no hint of the integral flux variability on daily scales at energies above 300 GeV if accounting for systematic uncertainties of the measurement. We ...

  13. Spread Spectrum Based Energy Efficient Collaborative Communication in Wireless Sensor Networks.

    Science.gov (United States)

    Ghani, Anwar; Naqvi, Husnain; Sher, Muhammad; Khan, Muazzam Ali; Khan, Imran; Irshad, Azeem

    2016-01-01

    Wireless sensor networks consist of resource limited devices. Most crucial of these resources is battery life, as in most applications like battle field or volcanic area monitoring, it is often impossible to replace or recharge the power source. This article presents an energy efficient collaborative communication system based on spread spectrum to achieve energy efficiency as well as immunity against jamming, natural interference, noise suppression and universal frequency reuse. Performance of the proposed system is evaluated using the received signal power, bit error rate (BER) and energy consumption. The results show a direct proportionality between the power gain and the number of collaborative nodes as well as BER and signal-to-noise ratio (Eb/N0). The analytical and simulation results of the proposed system are compared with SISO system. The comparison reveals that SISO perform better than collaborative communication in case of small distances whereas collaborative communication performs better than SISO in case of long distances. On the basis of these results it is safe to conclude that collaborative communication in wireless sensor networks using wideband systems improves the life time of nodes in the networks thereby prolonging the network's life time.

  14. Spread Spectrum Based Energy Efficient Collaborative Communication in Wireless Sensor Networks.

    Science.gov (United States)

    Ghani, Anwar; Naqvi, Husnain; Sher, Muhammad; Khan, Muazzam Ali; Khan, Imran; Irshad, Azeem

    2016-01-01

    Wireless sensor networks consist of resource limited devices. Most crucial of these resources is battery life, as in most applications like battle field or volcanic area monitoring, it is often impossible to replace or recharge the power source. This article presents an energy efficient collaborative communication system based on spread spectrum to achieve energy efficiency as well as immunity against jamming, natural interference, noise suppression and universal frequency reuse. Performance of the proposed system is evaluated using the received signal power, bit error rate (BER) and energy consumption. The results show a direct proportionality between the power gain and the number of collaborative nodes as well as BER and signal-to-noise ratio (Eb/N0). The analytical and simulation results of the proposed system are compared with SISO system. The comparison reveals that SISO perform better than collaborative communication in case of small distances whereas collaborative communication performs better than SISO in case of long distances. On the basis of these results it is safe to conclude that collaborative communication in wireless sensor networks using wideband systems improves the life time of nodes in the networks thereby prolonging the network's life time. PMID:27447489

  15. Spread Spectrum Based Energy Efficient Collaborative Communication in Wireless Sensor Networks

    Science.gov (United States)

    2016-01-01

    Wireless sensor networks consist of resource limited devices. Most crucial of these resources is battery life, as in most applications like battle field or volcanic area monitoring, it is often impossible to replace or recharge the power source. This article presents an energy efficient collaborative communication system based on spread spectrum to achieve energy efficiency as well as immunity against jamming, natural interference, noise suppression and universal frequency reuse. Performance of the proposed system is evaluated using the received signal power, bit error rate (BER) and energy consumption. The results show a direct proportionality between the power gain and the number of collaborative nodes as well as BER and signal-to-noise ratio (Eb/N0). The analytical and simulation results of the proposed system are compared with SISO system. The comparison reveals that SISO perform better than collaborative communication in case of small distances whereas collaborative communication performs better than SISO in case of long distances. On the basis of these results it is safe to conclude that collaborative communication in wireless sensor networks using wideband systems improves the life time of nodes in the networks thereby prolonging the network’s life time. PMID:27447489

  16. Measurement of low energy neutron spectrum below 10 keV with the slowing down time method

    Science.gov (United States)

    Maekawa, F.; Oyama, Y.

    1996-02-01

    No general-purpose method of neutron spectrum measurement in the energy region around eV has been established so far. Neutron spectrum measurement in this energy region was attempted by applying the slowing down time (SDT) method, for the first time, inside two types of shield for fusion reactors, type 316 stainless steel (SS316) and SS316/water layered assemblies, incorporating with pulsed neutrons. In the SS316 assembly, neutron spectra below 1 keV were measured with an accuracy less than 10%. Although application of the SDT method was expected very difficult for SS316/water assembly since it contained lightest atoms of hydrogen, the measurement demonstrated that the SDT method was still effective for such shield assembly. The SDT method was also extended to thermal flux measurement in the SS316/water assembly. The present study demonstrated that the SDT method was effective for neutron spectrum measurement in the energy region around eV.

  17. Anisotropies in the diffuse gamma-ray background measured by the Fermi LAT

    OpenAIRE

    Ackermann, M; Gomez-Vargas, G. A.; Fermi LAT collaboration

    2012-01-01

    Artículo escrito por muchos autores, sólo se relacionan el que aparece en primer lugar, los de la Universidad Autónoma de Madrid y el grupo de colaboración The contribution of unresolved sources to the diffuse gamma-ray background could induce anisotropies in this emission on small angular scales. We analyze the angular power spectrum of the diffuse emission measured by the Fermi Large Area Telescope at Galactic latitudes │b│ > 30˚ in four energy bins spanning 1–50 GeV. At multipoles ℓ ≥ 1...

  18. Analysis of effectiveness of spectrum of energy and image quality evaluation by aluminium filter in the added compound filtration

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Sang Hyun [Dept. of Dignostic Radiology, Seoul National University hospital, Seoul (Korea, Republic of); Choi, Jae Ho [Dept. of Radiological Technology, Ansan College, Ansan (Korea, Republic of)

    2015-09-15

    This study analysed the effectiveness of aluminium(Al) filter in the added compound filtration for the removal of characteristic radiation by energy spectrum and image evaluation. 0.1, 0.2, 0.3 mm copper with and without 1 mm Al were evaluated. The energy spectrum was measured using the GATE and evaluated separately by each energy. Image quality was evaluated by PSNR, MAE, MSE, CNR, SNR and qualitative analysis was performed by seven items for resolution and contrast from chest x-ray criteria of National Cancer Screening and Cardiovascular evaluation table. In the analysis of the quality of the energy per photon spectrum with the exception of a low energy region, without Al were superior in all area. PSNR MAE, MSE, CNR, SNR and qualitative analysis were the same or slightly better. PSNR was over 30 dB and all significant and the p>0.05 in the T-test of qualitative analysis. The energy spectrum and image quality have little difference between before and after use of Al filter. Therefore, it is effective to use the Al filter for the radiation dose management with the compensation capability of DR system.

  19. The Energy Spectrum of Atmospheric Neutrinos between 2 and 200 TeV with the AMANDA-II Detector

    Energy Technology Data Exchange (ETDEWEB)

    IceCube Collaboration; Abbasi, R.

    2010-05-11

    The muon and anti-muon neutrino energy spectrum is determined from 2000-2003 AMANDA telescope data using regularised unfolding. This is the first measurement of atmospheric neutrinos in the energy range 2-200 TeV. The result is compared to different atmospheric neutrino models and it is compatible with the atmospheric neutrinos from pion and kaon decays. No significant contribution from charm hadron decays or extraterrestrial neutrinos is detected. The capabilities to improve the measurement of the neutrino spectrum with the successor experiment IceCube are discussed.

  20. The quantum Kirchhoff equation and quantum current and energy spectrum of a homogeneous mesoscopic dissipation transmission line

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    On the basis of quantization of charge, the loop equations of quantum circuits are investigated by using the Heisenberg motion equation for a mesoscopic dissipation transmission line. On the supposition that the system has a symmetry under translation in charge space, the quantum current and the quantum energy spectrum in the mesoscopic transmission line are given by solving their eigenvalue equations. Results show that the quantum current and the quantum energy spectrum are not only related to the parameters of the transmission line, but also dependent on the quantized character of the charge obviously.

  1. Hints on the high-energy seesaw mechanism from the low-energy neutrino spectrum

    Energy Technology Data Exchange (ETDEWEB)

    Casas, J.A.; Jimenez-Alburquerque, F. [Univ. Autonoma de Madrid (Spain). IFT-UAM/CSIC, C-XVI; Ibarra, A. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)

    2006-12-15

    It is an experimental fact that the mass ratio for the two heavier neutrinos, h=m{sub 3}/m{sub 2}energy seesaw parameters and 2) Which choices, among the allowed ones, produce more naturally the observed pattern of neutrino masses. We have studied in particular if starting with hierarchical neutrino Yukawa couplings, as for the other fermions, one can naturally get the observed henergy) basis-independent quantities. Among the main results, we find that in most cases m{sub 3}/m{sub 2} >> m{sub 3}/m{sub 2}, so m{sub 1} should be extremely tiny. Also, the V{sub R} matrix associated to the neutrino Yukawa couplings has a far from random structure, naturally resembling V{sub CKM}. In fact we show that identifying V{sub R} and V{sub CKM}, as well as neutrino and u-quark Yukawa couplings can reproduce h{sup exp} in a highly non-trivial way, which is very suggestive. The physical implications of these results are also discussed. (orig.)

  2. Magnetic anisotropy in rare-earth metals

    DEFF Research Database (Denmark)

    Nielsen, Mourits; Bjerrum Møller, Hans; Lindgård, Per-Anker;

    1970-01-01

    The magnetic field dependence of the energy of long- wavelength magnons in Tb-10%Ho has been studied by inelastic neutron scattering. The results agree with the `frozen-lattice' model, provided that the second-order magnetoelastic effect is taken into account. The planar anisotropy is almost...

  3. Cosmic-ray energy spectrum and composition up to the ankle - the case for a second Galactic component

    CERN Document Server

    Thoudam, S; van Vliet, A; Achterberg, A; Buitink, S; Falcke, H; Hörandel, J R

    2016-01-01

    We have carried out a detailed study to understand the observed energy spectrum and composition of cosmic rays with energies up to ~10^18 eV. Our study shows that a single Galactic component with subsequent energy cut-offs in the individual spectra of different elements, optimised to explain the observed spectra below ~10^14 eV and the knee in the all-particle spectrum, cannot explain the observed all-particle spectrum above ~2x10^16 eV. We discuss two approaches for a second component of Galactic cosmic rays -- re-acceleration at a Galactic wind termination shock, and supernova explosions of Wolf-Rayet stars, and show that the latter scenario can explain almost all observed features in the all-particle spectrum and the composition up to ~10^18 eV, when combined with a canonical extra-galactic spectrum expected from strong radio galaxies or a source population with similar cosmological evolution. In this two-component Galactic model, the knee at ~ 3x10^15 eV and the second knee at ~10^17 eV in the all-particl...

  4. Anisotropy-graded media: Magnetic characterization

    Science.gov (United States)

    Lu, Zhihong; Visscher, P. B.; Harrell, J. W.

    2008-04-01

    The concept of exchange-coupled media (each grain having a soft end whose exchange field helps to switch a hard end) has recently been generalized to allow a continuous gradation of anisotropy from soft to hard. We have recently shown that the "figure of merit" for such media ξ =2Eb/μ0MsHsw, proportional to the ratio of the energy barrier Eb to the switching field Hsw, cannot exceed 4 for any anisotropy profile K(r ). In the thin-wall limit (exchange constant A ≪KL2), it can be made to approach 4 by choosing a graded anisotropy K(z )∝z2. In developing such a medium, it is important to be able to experimentally probe the anisotropy distribution. In this paper, we study one method for doing this, the hard axis loop. In the absence of exchange, the second derivative of this loop gives the distribution directly; we show that even in the presence of realistic exchange, this remains approximately true and the anisotropy distribution can be extracted from the hard axis loop.

  5. Computing magnetic anisotropy constants of single molecule magnets

    Indian Academy of Sciences (India)

    S Ramasesha; Shaon Sahoo; Rajamani Raghunathan; Diptiman Sen

    2009-09-01

    We present here a theoretical approach to compute the molecular magnetic anisotropy parameters, and for single molecule magnets in any given spin eigenstate of exchange spin Hamiltonian. We first describe a hybrid constant -valence bond (VB) technique of solving spin Hamiltonians employing full spatial and spin symmetry adaptation and we illustrate this technique by solving the exchange Hamiltonian of the Cu6Fe8 system. Treating the anisotropy Hamiltonian as perturbation, we compute the and values for various eigenstates of the exchange Hamiltonian. Since, the dipolar contribution to the magnetic anisotropy is negligibly small, we calculate the molecular anisotropy from the single-ion anisotropies of the metal centers. We have studied the variation of and by rotating the single-ion anisotropies in the case of Mn12Ac and Fe8 SMMs in ground and few low-lying excited states of the exchange Hamiltonian. In both the systems, we find that the molecular anisotropy changes drastically when the single-ion anisotropies are rotated. While in Mn12Ac SMM values depend strongly on the spin of the eigenstate, it is almost independent of the spin of the eigenstate in Fe8 SMM. We also find that the value is almost insensitive to the orientation of the anisotropy of the core Mn(IV) ions. The dependence of on the energy gap between the ground and the excited states in both the systems has also been studied by using different sets of exchange constants.

  6. Energy spectrum of ensemble of weakly nonlinear gravity-capillary waves on a fluid surface

    CERN Document Server

    Tobisch, Elena

    2014-01-01

    In this Letter we regard nonlinear gravity-capillary waves with parameter of nonlinearity being $\\varepsilon \\sim 0.1 \\div 0.25$. For this nonlinearity time scale separation does not occur and kinetic wave equation does not hold. An energy cascade in this case is built at the dynamic time scale (D-cascade) and is computed by the increment chain equation method first introduced in \\emph{Kartashova, \\emph{EPL} \\textbf{97} (2012), 30004.} We compute for the first time an analytical expression for the energy spectrum of nonlinear gravity-capillary waves as an explicit function depending on the ratio of surface tension to the gravity acceleration. It is shown that its two limits - pure capillary and pure gravity waves on a fluid surface - coincide with the previously obtained results. We also discuss relations of the model of D-cascade with a few known models used in the theory of nonlinear waves such as Zakharov's equation, resonance of the modes with nonlinear Stokes corrected frequencies and Benjamin-Feir index...

  7. Energy/bandwidth-Saving Cooperative Spectrum Sensing for Two-hopWRAN

    Directory of Open Access Journals (Sweden)

    Ming-Tuo Zhou

    2014-07-01

    Full Text Available A two-hop wireless regional area network (WRAN providing monitoring services operating in Television White Space (TVWS, i.e., IEEE P802.22b, may employ a great number of subscriber customer-premises equipments (S-CPEs possibly without mains power supply, leading to requirement of cost-effective and power-saving design. This paper proposes a framework of cooperative spectrum sensing (CSS and an energy/bandwidth saving CSS scheme to P802.22b. In each round of sensing, S-CPEs with SNRs lower than a predefined threshold are excluded from reporting sensing results. Numerical results show that the fused missed-detection probability and false alarmprobability could remainmeeting sensing requirements, and the overall fused error probability changes very little. With 10 S-CPEs, it is possible to save more than 40% of the energy/bandwidth on a Rayleigh channel. The principle proposed can apply to other advanced sensing technologies capable of detecting primary signals with low average SNR.

  8. Polynomial potentials determined from the energy spectrum and transition dipole moments that give the largest hyperpolarizabilities

    CERN Document Server

    Dawson, Nathan J

    2016-01-01

    We attempt to get a polynomial solution to the inverse problem, that is, to determine the form of the mechanical Hamiltonian when given the energy spectrum and transition dipole moment matrix. This is related to the famous problem of "hearing the shape of a drumhead," as originally stated by Koch [see Mark Kac, "Can One Hear the Shape of a Drum?" Mathematical Monthly vol. 73, 1 (1966)]. The ideal energy spacing to get hyperpolarizabilities at the limit can be determined from Monte Carlo techniques [see M. C. Kuzyk and M. G. Kuzyk, "Monte Carlo Studies of the Fundamental Limits of the Intrinsic Hyperpolarizability," J. Opt. Soc. Am. B vol. 23, 103 (2008).]; but, there is no reliable way to get the underlying Hamiltonian. Our approach is to determine the potential in the form of a polynomial by finding an approximate solution to the inverse problem, then to determine the hyperpolarizability for that system's Hamiltonian. We find that the largest hyperpolarizabilities approach the apparent limit of previous pote...

  9. Heisenberg antiferromagnet on Cayley trees: Low-energy spectrum and even/odd site imbalance

    Science.gov (United States)

    Changlani, Hitesh J.; Ghosh, Shivam; Henley, Christopher L.; Läuchli, Andreas M.

    2013-02-01

    To understand the role of local sublattice imbalance in low-energy spectra of s=(1)/(2) quantum antiferromagnets, we study the s=(1)/(2) quantum nearest neighbor Heisenberg antiferromagnet on the coordination 3 Cayley tree. We perform many-body calculations using an implementation of the density matrix renormalization group (DMRG) technique for generic tree graphs. We discover that the bond-centered Cayley tree has a quasidegenerate set of a low-lying tower of states and an “anomalous” singlet-triplet finite-size gap scaling. For understanding the construction of the first excited state from the many-body ground state, we consider a wave function ansatz given by the single-mode approximation, which yields a high overlap with the DMRG wave function. Observing the ground-state entanglement spectrum leads us to a picture of the low-energy degrees of freedom being “giant spins” arising out of sublattice imbalance, which helps us analytically understand the scaling of the finite-size spin gap. The Schwinger-boson mean-field theory has been generalized to nonuniform lattices, and ground states have been found which are spatially inhomogeneous in the mean-field parameters.

  10. Obscured flat spectrum radio AGN as sources of high-energy neutrinos

    CERN Document Server

    Maggi, G; Correa, P; de Vries, K D; Gentile, G; Tavares, J Leon; Scholten, O; van Eijndhoven, N; Vereecken, M; Winchen, T

    2016-01-01

    Active Galactic Nuclei (AGN) are believed to be one of the main source candidates for the high-energy (TeV-PeV) cosmic neutrino flux recently discovered by the IceCube neutrino observatory. Nevertheless, several correlation studies between AGN and the cosmic neutrinos detected by IceCube show no significance. Therefore, in this article we consider a specific sub-class of AGN for which an increased neutrino production is expected. This sub-class contains AGN for which their high-energy jet is pointing toward Earth. Furthermore, we impose the condition that the jet is obscured by gas or dust surrounding the AGN. A method is presented to determine the total column density of the obscuring medium, which is probed by determining the relative X-ray attenuation with respect to the radio flux as obtained from the AGN spectrum. The total column density allows us to probe the interaction of the jet with the surrounding matter which leads to additional neutrino production. Finally, starting from two different source cat...

  11. The Spectrum of Thorium from 250 nm to 5500 nm: Ritz Wavelengths and Optimized Energy Levels

    CERN Document Server

    Redman, Stephen L; Sansonetti, Craig J

    2013-01-01

    We have made precise observations of a thorium-argon hollow cathode lamp emission spectrum in the region between 350 nm and 1175 nm using a high-resolution Fourier transform spectrometer. Our measurements are combined with results from seven previously published thorium line lists (Giacchetti et al. 1974; Zalubas & Corliss 1974; Zalubas 1976; Palmer & Engleman 1983; Engleman et al. 2003; Lovis & Pepe 2007; Kerber et al. 2008) to re-optimize the energy levels of neutral, singly-, and doubly-ionized thorium (Th I, Th II, and Th III). Using the optimized level values, we calculate accurate Ritz wavelengths for 19679 thorium lines between 250 nm and 5500 nm (40000 1/cm to 1800 1/cm). We have also found 102 new thorium energy levels. A systematic analysis of previous measurements in light of our new results allows us to identify and propose corrections for systematic errors in Palmer & Engleman (1983) and typographical errors and incorrect classifications in Kerber et al. (2008). We also found a la...

  12. CMB Anisotropy due to Cosmic Strings in an Accelerated Expanding Universe

    CERN Document Server

    Rokni, S Y; Bordbar, M R

    2013-01-01

    We want to find the cosmological constant influence on cosmic microwave background (CMB) anisotropy due to cosmic strings. Considering the space-time metric of a cosmic string under the effect of a positive cosmological constant, the CMB anisotropy is studied. The result shows that a positive cosmological constant (i.e. the presence of cosmic strings in an accelerated expanding universe) weakens the anisotropy so that more strong resolution is needed to detect the corresponding influences on the CMB power spectrum.

  13. Physics of the cosmic microwave background anisotropy

    CERN Document Server

    Bucher, Martin

    2015-01-01

    Observations of the cosmic microwave background (CMB), especially of its frequency spectrum and its anisotropies, both in temperature and in polarization, have played a key role in the development of modern cosmology and our understanding of the very early universe. We review the underlying physics of the CMB and how the primordial temperature and polarization anisotropies were imprinted. Possibilities for distinguishing competing cosmological models are emphasized. The current status of CMB experiments and experimental techniques with an emphasis toward future observations, particularly in polarization, is reviewed. The physics of foreground emissions, especially of polarized dust, is discussed in detail, since this area is likely to become crucial for measurements of the B modes of the CMB polarization at ever greater sensitivity.

  14. Origin of the ankle in the ultra-high energy cosmic ray spectrum and of the extragalactic protons below it

    CERN Document Server

    Farrar, Glennys R; Anchordoqui, Luis A

    2015-01-01

    The sharp change in slope of the ultra-high energy cosmic ray (UHECR) spectrum around 10^{18.6} eV (the ankle), combined with evidence of a light but extragalactic component near and below the ankle which evolves to intermediate composition above, has proved exceedingly challenging to understand theoretically. We show that for a range of source conditions, photo-disintegration of ultra-high energy nuclei in the region surrounding a UHECR accelerator naturally accounts for the observed spectrum and composition of the entire extragalactic component, which dominates above about 10^{17.5} eV. The mechanism has a clear signature in the spectrum and flavors of neutrinos.

  15. Magnetotransport in double quantum well with inverted energy spectrum: HgTe/CdHgTe

    Science.gov (United States)

    Yakunin, M. V.; Suslov, A. V.; Popov, M. R.; Novik, E. G.; Dvoretsky, S. A.; Mikhailov, N. N.

    2016-02-01

    We present an experimental study of the double-quantum-well (DQW) system made of two-dimensional layers with inverted energy band spectrum: HgTe. The magnetotransport reveals a considerably larger overlap of the conduction and valence subbands than in known HgTe single quantum wells (QW), which may be regulated here by an applied gate voltage Vg. This large overlap manifests itself in a much higher critical field Bc separating the range above it with a plain behavior of the Hall magnetoresistance ρx y(B ) , where the quantum peculiarities shift linearly with Vg, and the range below with a complicated behavior. In the latter case, specific structures in ρx y(B ) are formed like a double-N -shaped ρx y(B ) , reentrant sign-alternating quantum Hall effect with transitions into a zero-filling-factor state, etc., which are clearly manifested here due to better magnetic quantization at high fields, as compared to the features seen earlier in a single HgTe QW. The coexisting electrons and holes were found in the whole investigated range of positive and negative Vg as revealed (i) from fits to the low-field N -shaped ρx y(B ) , (ii) from the Fourier analysis of oscillations in ρx x(B ) , and (iii) from a specific behavior of ρx y(B ) at high positive Vg. A peculiar feature here is that the found electron density n remains almost constant in the whole range of investigated Vg while the hole density p drops down from the value a factor of 6 larger than n at extreme negative Vg to almost zero at extreme positive Vg passing through the charge-neutrality point. We show that this difference between n and p stems from an order of magnitude larger density of states for holes in the lateral valence subband maxima than for electrons in the conduction subband minimum. We analyze our observations on the basis of a calculated picture of magnetic levels in a DQW and suggest that their specificity is due to (i) a nonmonotonic course of the valence subband magnetic levels and an

  16. Measurement of the energy spectrum of cosmic rays above 10(18) eV using the Pierre Auger Observatory

    NARCIS (Netherlands)

    Abraham, J.; Abreu, P.; Aglietta, M.; Ahn, E. J.; Allard, D.; Allen, J.; Alvarez-Muniz, J.; Ambrosio, M.; Anchordoqui, L.; Andringa, S.; Anticic, T.; Anzalone, A.; Aramo, C.; Arganda, E.; Arisaka, K.; Arqueros, F.; Asorey, H.; Assis, P.; Aublin, J.; Ave, M.; Avila, G.; Baecker, T.; Badagnani, D.; Balzer, M.; Barber, K. B.; Barbosa, A. F.; Barroso, S. L. C.; Baughman, B.; Bauleo, P.; Beatty, J. J.; Becker, B. R.; Becker, K. H.; Belletoile, A.; Bellido, J. A.; BenZvi, S.; Berat, C.; Bergmann, T.; Bertou, X.; Biermann, P. L.; Billoir, P.; Blanch-Bigas, O.; Blanco, F.; Blanco, M.; Bleve, C.; Bluemer, H.; Bohacova, M.; Boncioli, D.; Bonifazi, C.; Bonino, R.; Borodai, N.; Brack, J.; Brogueira, P.; Brown, W. C.; Bruijn, R.; Buchholz, P.; Bueno, A.; Burton, R. E.; Busca, N. G.; Caballero-Mora, K. S.; Caramete, L.; Caruso, R.; Castellina, A.; Catalano, O.; Cataldi, G.; Cazon, L.; Cester, R.; Chauvin, J.; Chiavassa, A.; Chinellato, J. A.; Chou, A.; Chudoba, J.; Clay, R. W.; Colombo, E.; Coluccia, M. R.; Conceicao, R.; Contreras, F.; Cook, H.; Cooper, M. J.; Coppens, J.; Cordier, A.; Cotti, U.; Coutu, S.; Covault, C. E.; Creusot, A.; Criss, A.; Cronin, J.; Curutiu, A.; Dagoret-Campagne, S.; Dallier, R.; Daumiller, K.; Dawson, B. R.; de Almeida, R. M.; De Domenico, M.; De Donato, C.; de Jong, S. J.; De La Vega, G.; de Mello Junior, W. J. M.; de Mello Neto, J. R. T.; De Mitri, I.; de Souza, V.; de Vries, K. D.; Decerprit, G.; del Peral, L.; Deligny, O.; Della Selva, A.; Delle Fratte, C.; Dembinski, H.; Di Giulio, C.; Diaz, J. C.; Diaz Castro, M. L.; Diep, P. N.; Dobrigkeit, C.; D'Olivo, J. C.; Dong, P. N.; Dorofeev, A.; dos Anjos, J. C.; Dova, M. T.; D'Urso, D.; Dutan, I.; DuVernois, M. A.; Ebr, J.; Engel, R.; Erdmann, M.; Escobar, C. O.; Etchegoyen, A.; San Luis, P. Facal; Falcke, H.; Farrar, G.; Fauth, A. C.; Fazzini, N.; Ferrero, A.; Fick, B.; Filevich, A.; Filipcic, A.; Fleck, I.; Fliescher, S.; Fracchiolla, C. E.; Fraenkel, E. D.; Froehlich, U.; Fulgione, W.; Gamarra, R. F.; Gambetta, S.; Garcia, B.; Garcia Gamez, D.; Garcia-Pinto, D.; Garrido, X.; Gelmini, G.; Gemmeke, H.; Ghia, P. L.; Giaccari, U.; Giller, M.; Glass, H.; Goggin, L. M.; Gold, M. S.; Golup, G.; Gomez Albarracin, F.; Gomez Berisso, M.; Goncalves, P.; Gonzalez, D.; Gonzalez, J. G.; Gora, D.; Gorgi, A.; Gouffon, P.; Gozzini, S. R.; Grashorn, E.; Grebe, S.; Grigat, M.; Grillo, A. F.; Guardincerri, Y.; Guarino, F.; Guedes, G. P.; Hague, J. D.; Halenka, V.; Hansen, P.; Harari, D.; Harmsma, S.; Harton, J. L.; Haungs, A.; Hebbeker, T.; Heck, D.; Herve, A. E.; Hojvat, C.; Holmes, V. C.; Homola, P.; Horandel, J. R.; Horneffer, A.; Hrabovsky, M.; Huege, T.; Hussain, M.; Iarlori, M.; Insolia, A.; Ionita, F.; Italiano, A.; Jiraskova, S.; Kadija, K.; Kaducak, M.; Kampert, K. H.; Karova, T.; Kasper, P.; Kegl, B.; Keilhauer, B.; Keivani, A.; Kelley, J.; Kemp, E.; Kieckhafer, R. M.; Klages, H. O.; Kleifges, M.; Kleinfeller, J.; Knapik, R.; Knapp, J.; Koang, D. -H.; Krieger, A.; Kroemer, O.; Kruppke-Hansen, D.; Kuehn, F.; Kuempel, D.; Kulbartz, K.; Kunka, N.; Kusenko, A.; La Rosa, G.; Lachaud, C.; Lago, B. L.; Lautridou, P.; Leao, M. S. A. B.; Lebrun, D.; Lebrun, P.; Lee, J.; Leigui de Oliveira, M. A.; Lemiere, A.; Letessier-Selvon, A.; Lhenry-Yvon, I.; Lopez, R.; Lopez Agueera, A.; Louedec, K.; Lozano Bahilo, J.; Lucero, A.; Ludwig, M.; Lyberis, H.; Maccarone, M. C.; Macolino, C.; Maldera, S.; Mandat, D.; Mantsch, P.; Mariazzi, A. G.; Marin, V.; Maris, I. C.; Marquez Falcon, H. R.; Marsella, G.; Martello, D.; Martinez Bravo, O.; Mathes, H. J.; Matthews, J.; Matthews, J. A. J.; Matthiae, G.; Maurizio, D.; Mazur, P. O.; McEwen, M.; Medina-Tanco, G.; Melissas, M.; Melo, D.; Menichetti, E.; Menshikov, A.; Meurer, C.; Micanovic, S.; Micheletti, M. I.; Miller, W.; Miramonti, L.; Mollerach, S.; Monasor, M.; Ragaigne, D. Monnier; Montanet, F.; Morales, B.; Morello, C.; Moreno, E.; Moreno, J. C.; Morris, C.; Mostafa, M.; Mueller, S.; Muller, M. A.; Mussa, R.; Navarra, G.; Navarro, J. L.; Navas, S.; Necesal, P.; Nellen, L.; Nhung, P. T.; Nierstenhoefer, N.; Nitz, D.; Nosek, D.; Nozka, L.; Nyklicek, M.; Oehlschlaeger, J.; Olinto, A.; Oliva, P.; Olmos-Gilbaja, V. M.; Ortiz, M.; Pacheco, N.; Selmi-Dei, D. Pakk; Palatka, M.; Pallotta, J.; Palmieri, N.; Parente, G.; Parizot, E.; Parlati, S.; Parra, A.; Parrisius, J.; Parsons, R. D.; Pastor, S.; Paul, T.; Pavlidou, V.; Payet, K.; Pech, M.; Pekala, J.; Pelayo, R.; Pepe, I. M.; Perrone, L.; Pesce, R.; Petermann, E.; Petrera, S.; Petrinca, P.; Petrolini, A.; Petrov, Y.; Petrovic, J.; Pfendner, C.; Piegaia, R.; Pierog, T.; Pimenta, M.; Pirronello, V.; Platino, M.; Ponce, V. H.; Pontz, M.; Privitera, P.; Prouza, M.; Quel, E. J.; Rautenberg, J.; Ravel, O.; Ravignani, D.; Redondo, A.; Revenu, B.; Rezende, F. A. S.

    2010-01-01

    We report a measurement of the flux of cosmic rays with unprecedented precision and Statistics using the Pierre Auger Observatory Based on fluorescence observations in coincidence with at least one Surface detector we derive a spectrum for energies above 10(18) eV We also update the previously publi

  17. Energy Spectrum of the Recurrent Variation of Galactic Cosmic Rays During the Solar Minimum of Cycles 23/24

    Science.gov (United States)

    Gil, Agnieszka; Alania, Michael V.

    2016-07-01

    The Sun during the recent epoch of solar activity operated in a different way than during the last 60 years, being less active. We study temporal changes of the energy spectrum of the first three harmonics of the 27-day variation of the galactic cosmic rays (GCR) intensity during the unusual, recent solar minimum, between Solar Cycles 23 and 24 (SC 23/24) and compare with four previous minima. We show that the energy spectrum of the amplitudes of the recurrent variation of the GCR intensity is hard in the maximum epochs and is soft in the minimum epochs during Solar Cycles 20 - 24, but with peculiarities during the Solar Minimum 23/24. In particular, while the energy/rigidity spectrum of the amplitudes of the first harmonic of the recurrent variation of the GCR intensity behaves practically the same as for previous epochs, the energy/rigidity spectrum of the amplitudes of the second and the third harmonics demonstrates a pronounced softening. We attribute this phenomenon to the decrease of the extension of the heliosphere caused by the decrease of the solar-wind dynamic pressure during the unusual Solar Minimum 23/24.

  18. A rigorous description of the energy spectrum of the isopropanol molecule taking into account the internal rotation of hydroxyl

    Science.gov (United States)

    Burenin, A. V.

    2016-06-01

    Using the methods of a group chain, a rigorous algebraic model is constructed to describe the energy spectrum of the isopropanol molecule (CH3)2CHOH with an allowance for the internal rotation of hydroxyl. The model is rigorous in the sense that its correctness is limited only by the correctness of a chosen symmetry of internal dynamics of the molecule.

  19. Energy Spectrum of the Recurrent Variation of Galactic Cosmic Rays During the Solar Minimum of Cycles 23/24

    Science.gov (United States)

    Gil, Agnieszka; Alania, Michael V.

    2016-08-01

    The Sun during the recent epoch of solar activity operated in a different way than during the last 60 years, being less active. We study temporal changes of the energy spectrum of the first three harmonics of the 27-day variation of the galactic cosmic rays (GCR) intensity during the unusual, recent solar minimum, between Solar Cycles 23 and 24 (SC 23/24) and compare with four previous minima. We show that the energy spectrum of the amplitudes of the recurrent variation of the GCR intensity is hard in the maximum epochs and is soft in the minimum epochs during Solar Cycles 20 - 24, but with peculiarities during the Solar Minimum 23/24. In particular, while the energy/rigidity spectrum of the amplitudes of the first harmonic of the recurrent variation of the GCR intensity behaves practically the same as for previous epochs, the energy/rigidity spectrum of the amplitudes of the second and the third harmonics demonstrates a pronounced softening. We attribute this phenomenon to the decrease of the extension of the heliosphere caused by the decrease of the solar-wind dynamic pressure during the unusual Solar Minimum 23/24.

  20. The gamma-ray spectrum of Geminga and the inverse Compton model of pulsar high energy emission

    CERN Document Server

    Lyutikov, Maxim

    2012-01-01

    We reanalyze the Fermi spectra of the Geminga and Vela pulsars. We find that the spectrum of Geminga above the break is exceptionally well approximated by a simple power law without the exponential cut-off, making Geminga's spectrum similar to that of Crab. Vela's broadband gamma-ray spectrum is equally well fit with both the exponential cut-off and the double power law shapes. In the broadband double power-law fits, for a typical Fermi spectrum of a bright \\gamma-ray pulsar, most of the errors accumulate due to the arbitrary parametrization of the spectral roll-off. In addition, a power law with an exponential cut-off gives an acceptable fit for the underlying double power-law spectrum for a very broad range of parameters, making such fitting procedures insensitive to the underlying Fermi photon spectrum. Our results have important implications for the mechanism of pulsar high energy emission. A number of observed properties of \\gamma-ray pulsars, i.e., the broken power law spectra without exponential cut-of...

  1. Energy spectrum of cosmic protons and helium nuclei by a hybrid measurement at 4300 m a.s.l

    International Nuclear Information System (INIS)

    The energy spectrum of cosmic Hydrogen and Helium nuclei has been measured below the so-called 'knee' by using a hybrid experiment with a wide field-of-view Cherenkov telescope and the Resistive Plate Chamber (RPC) array of the ARGO-YBJ experiment at 4300 m above sea level. The Hydrogen and Helium nuclei have been well separated from other cosmic ray components by using a multi-parameter technique. A highly uniform energy resolution of about 25% is achieved throughout the whole energy range (100-700 TeV). The observed energy spectrum is compatible with a single power law with index γ=-2.63±0.06. (authors)

  2. Energy Spectrum of Cosmic Protons and Helium Nuclei by a Hybrid Measurement at 4300 m a.s.l

    CERN Document Server

    Bartoli, B; Bi, X J; Bolognino, I; Branchini, P; Budano, A; Melcarne, A K Calabrese; Camarri, P; Cao, Z; Cardarelli, R; Catalanotti, S; Chen, S Z; Chen, T L; Creti, P; Cui, S W; Dai, B Z; D'Amone, A; Danzengluobu,; De Mitri, I; Piazzoli, B D'Ettorre; Di Girolamo, T; Di Sciascio, G; Feng, C F; Feng, Zhaoyang; Feng, Zhenyong; Gou, Q B; Guo, Y Q; He, H H; Hu, Haibing; Hu, Hongbo; Iacovacci, M; Iuppa, R; Jia, H Y; Labaciren,; Li, H J; Liguori, G; Liu, C; Liu, J; Liu, M Y; Lu, H; Ma, L L; Ma, X H; Mancarella, G; Mari, S M; Marsella, G; Martello, D; Mastroianni, S; Montini, P; Ning, C C; Panareo, M; Panico, B; Perrone, L; Pistilli8, P; Ruggieri, F; Salvini, P; Santonico, R; Sbano, S N; Shen, P R; Sheng, X D; Shi, F; Surdo, A; Tan, Y H; Vallania, P; Vernetto, S; Vigorito, C; Wang, H; Wu, C Y; Wu, H R; Xue, L; Yang, Q Y; Yang, X C; Yao, Z G; Yuan, A F; Zha, M; Zhang, H M; Zhang, L; Zhang, X Y; Zhang, Y; Zhao, J; Zhaxiciren,; Zhaxisangzhu,; Zhou, X X; Zhu, F R; Zhu, Q Q; Bai, B X; Chen, M J; Chen, Y; Feng, S H; Gao, B; Gu, M H; Hou, C; Li, X X; Liu, J L; Wang, X; Xiao, G; Zhang, B K; Zhang, S S; Zhou, B

    2014-01-01

    The energy spectrum of cosmic Hydrogen and Helium nuclei has been measured, below the so-called "knee", by using a hybrid experiment with a wide field-of-view Cherenkov telescope and the Resistive Plate Chamber (RPC) array of the ARGO-YBJ experiment at 4300 m above sea level. The Hydrogen and Helium nuclei have been well separated from other cosmic ray components by using a multi-parameter technique. A highly uniform energy resolution of about 25% is achieved throughout the whole energy range (100 TeV - 700 TeV). The observed energy spectrum is compatible with a single power law with index gamma=-2.63+/-0.06.

  3. Searches for Large-Scale Anisotropy in the Arrival Directions of Cosmic Rays Detected above Energy of $10^{19}$ eV at the Pierre Auger Observatory and the Telescope Array

    Energy Technology Data Exchange (ETDEWEB)

    Aab, Alexander; et al,

    2014-10-07

    Spherical harmonic moments are well-suited for capturing anisotropy at any scale in the flux of cosmic rays. An unambiguous measurement of the full set of spherical harmonic coefficients requires full-sky coverage. This can be achieved by combining data from observatories located in both the northern and southern hemispheres. To this end, a joint analysis using data recorded at the Telescope Array and the Pierre Auger Observatory above 1019 eV is presented in this work. The resulting multipolar expansion of the flux of cosmic rays allows us to perform a series of anisotropy searches, and in particular to report on the angular power spectrum of cosmic rays above 1019 eV. No significant deviation from isotropic expectations is found throughout the analyses performed. Upper limits on the amplitudes of the dipole and quadrupole moments are derived as a function of the direction in the sky, varying between 7% and 13% for the dipole and between 7% and 10% for a symmetric quadrupole.

  4. Searches for large-scale anisotropy in the arrival directions of cosmic rays detected above energy of 10{sup 19} eV at the Pierre Auger observatory and the telescope array

    Energy Technology Data Exchange (ETDEWEB)

    Aab, A. [Universität Siegen, Siegen (Germany); Abreu, P.; Andringa, S. [Laboratório de Instrumentação e Física Experimental de Partículas-LIP and Instituto Superior Técnico-IST, Universidade de Lisboa-UL (Portugal); Aglietta, M. [Osservatorio Astrofisico di Torino (INAF), Università di Torino and Sezione INFN, Torino (Italy); Ahn, E. J. [Fermilab, Batavia, IL (United States); Al Samarai, I. [Institut de Physique Nucléaire d' Orsay (IPNO), Université Paris 11, CNRS-IN2P3, Orsay (France); Albuquerque, I. F. M. [Universidade de São Paulo, Instituto de Física, São Paulo, SP (Brazil); Allekotte, I.; Asorey, H. [Centro Atómico Bariloche and Instituto Balseiro (CNEA-UNCuyo-CONICET), San Carlos de Bariloche (Argentina); Allen, J. [New York University, New York, NY (United States); Allison, P. [Ohio State University, Columbus, OH (United States); Almela, A. [Universidad Tecnológica Nacional - Facultad Regional Buenos Aires, Buenos Aires (Argentina); Castillo, J. Alvarez [Universidad Nacional Autonoma de Mexico, Mexico, D. F. (Mexico); Alvarez-Muñiz, J. [Universidad de Santiago de Compostela (Spain); Batista, R. Alves [Universität Hamburg, Hamburg (Germany); Ambrosio, M.; Aramo, C. [Università di Napoli " Federico II" and Sezione INFN, Napoli (Italy); Aminaei, A. [IMAPP, Radboud University Nijmegen (Netherlands); Anchordoqui, L. [University of Wisconsin, Milwaukee, WI (United States); Arqueros, F. [Universidad Complutense de Madrid, Madrid (Spain); Collaboration: Pierre Auger Collaboration; Telescope Array Collaboration; and others

    2014-10-20

    Spherical harmonic moments are well-suited for capturing anisotropy at any scale in the flux of cosmic rays. An unambiguous measurement of the full set of spherical harmonic coefficients requires full-sky coverage. This can be achieved by combining data from observatories located in both the northern and southern hemispheres. To this end, a joint analysis using data recorded at the Telescope Array and the Pierre Auger Observatory above 10{sup 19} eV is presented in this work. The resulting multipolar expansion of the flux of cosmic rays allows us to perform a series of anisotropy searches, and in particular to report on the angular power spectrum of cosmic rays above 10{sup 19} eV. No significant deviation from isotropic expectations is found throughout the analyses performed. Upper limits on the amplitudes of the dipole and quadrupole moments are derived as a function of the direction in the sky, varying between 7% and 13% for the dipole and between 7% and 10% for a symmetric quadrupole.

  5. Searches for Large-Scale Anisotropy in the Arrival Directions of Cosmic Rays Detected above Energy of $10^{19}$ eV at the Pierre Auger Observatory and the Telescope Array

    CERN Document Server

    Auger, The Pierre; Aab, A; Abreu, P; Aglietta, M; Ahn, E J; Al, I; Albuquerque, I F M; Allekotte, I; Allen, J; Allison, P; Almela, A; Alvarez, J; Alvarez-Muñiz, J; Alves, R; Ambrosio, M; Aminaei, A; Anchordoqui, L; Andringa, S; Aramo, C; Arqueros, F; Asorey, H; Assis, P; Aublin, J; Ave, M; Avenier, M; Avila, G; Badescu, A M; Barber, K B; Bäuml, J; Baus, C; Beatty, J J; Becker, K H; Bellido, J A; Berat, C; Bertou, X; Biermann, P L; Billoir, P; Blanco, M; Bleve, C; Blümer, H; Boháčová, M; Boncioli, D; Bonifazi, C; Bonino, R; Borodai, N; Brack, J; Brancus, I; Brogueira, P; Brown, W C; Buchholz, P; Bueno, A; Buitink, S; Buscemi, M; Caballero-Mora, K S; Caccianiga, B; Caccianiga, L; Candusso, M; Caramete, L; Caruso, R; Castellina, A; Cataldi, G; Cazon, L; Cester, R; Chavez, A G; Chiavassa, A; Chinellato, J A; Chudoba, J; Cilmo, M; Clay, R W; Cocciolo, G; Colalillo, R; Coleman, A; Collica, L; Coluccia, M R; Conceição, R; Contreras, F; Cooper, M J; Cordier, A; Coutu, S; Covault, C E; Cronin, J; Curutiu, A; Dallier, R; Daniel, B; Dasso, S; Daumiller, K; Dawson, B R; de, R M; De, M; de, S J; de, J R T; De, I; de, J; de, V; del, L; Deligny, O; Dembinski, H; Dhital, N; Di, C; Di, A; Diaz, J C; Díaz, M L; Diogo, F; Dobrigkeit, C; Docters, W; D'Olivo, J C; Dorofeev, A; Dorosti, Q; Dova, M T; Ebr, J; Engel, R; Erdmann, M; Erfani, M; Escobar, C O; Espadanal, J; Etchegoyen, A; Facal, P; Falcke, H; Fang, K; Farrar, G; Fauth, A C; Fazzini, N; Ferguson, A P; Fernandes, M; Fick, B; Figueira, J M; Filevich, A; Filipčič, A; Fox, B D; Fratu, O; Fröhlich, U; Fuchs, B; Fuji, T; Gaior, R; García, B; Garcia, S T; Garcia-Gamez, D; Garcia-Pinto, D; Garilli, G; Gascon, A; Gate, F; Gemmeke, H; Ghia, P L; Giaccari, U; Giammarchi, M; Giller, M; Glaser, C; Glass, H; Gómez, M; Gómez, P F; Gonçalves, P; Gonzalez, J G; González, N; Gookin, B; Gorgi, A; Gorham, P; Gouffon, P; Grebe, S; Griffith, N; Grillo, A F; Grubb, T D; Guardincerri, Y; Guarino, F; Guedes, G P; Hampel, M R; Hansen, P; Harari, D; Harrison, T A; Hartmann, S; Harton, J L; Haungs, A; Hebbeker, T; Heck, D; Heimann, P; Herve, A E; Hill, G C; Hojvat, C; Hollon, N; Holt, E; Homola, P; Hörandel, J R; Horvath, P; Hrabovský, M; Huber, D; Huege, T; Insolia, A; Isar, P G; Islo, K; Jandt, I; Jansen, S; Jarne, C; Josebachuili, M; Kääpä, A; Kambeitz, O; Kampert, K H; Kasper, P; Katkov, I; Kégl, B; Keilhauer, B; Keivani, A; Kemp, E; Kieckhafer, R M; Klages, H O; Kleifges, M; Kleinfeller, J; Krause, R; Krohm, N; Krömer, O; Kruppke-Hansen, D; Kuempel, D; Kunka, N; La, G; LaHurd, D; Latronico, L; Lauer, R; Lauscher, M; Lautridou, P; Le, S; Leão, M S A B; Lebrun, D; Lebrun, P; Leigui, M A; Letessier-Selvon, A; Lhenry-Yvon, I; Link, K; López, R; Lopez, A; Louedec, K; Lozano, J; Lu, L; Lucero, A; Ludwig, M; Maccarone, M C; Malacari, M; Maldera, S; Mallamaci, M; Maller, J; Mandat, D; Mantsch, P; Mariazzi, A G; Marin, V; Mariş, I C; Marsella, G; Martello, D; Martin, L; Martinez, H; Martínez, O; Martraire, D; Masías, J J; Mathes, H J; Mathys, S; Matthews, J A J; Matthews, J; Matthiae, G; Maurel, D; Maurizio, D; Mayotte, E; Mazur, P O; Medina, C; Medina-Tanco, G; Melissas, M; Melo, D; Menichetti, E; Menshikov, A; Messina, S; Meyhandan, R; Mićanović, S; Micheletti, M I; Middendorf, L; Minaya, I A; Miramonti, L; Mitrica, B; Molina-Bueno, L; Mollerach, S; Monasor, M; Monnier, D; Montanet, F; Morello, C; Mostafá, M; Moura, C A; Muller, M A; Müller, G; Münchmeyer, M; Mussa, R; Navarra, G; Navas, S; Necesal, P; Nellen, L; Nelles, A; Neuser, J; Niechciol, M; Niemietz, L; Niggemann, T; Nitz, D; Nosek, D; Novotny, V; Nožka, L; Ochilo, L; Olinto, A; Oliveira, M; Pacheco, N; Pakk, D; Palatka, M; Pallotta, J; Palmieri, N; Papenbreer, P; Parente, G; Parra, A; Paul, T; Pech, M; Pȩkala, J; Pelayo, R; Pepe, I M; Perrone, L; Pesce, R; Petermann, E; Peters, C; Petrera, S; Petrolini, A; Petrov, Y; Phuntsok, J; Piegaia, R; Pierog, T; Pieroni, P; Pimenta, M; Pirronello, V; Platino, M; Plum, M; Porcelli, A; Porowski, C; Prado, R R; Privitera, P; Prouza, M; Purrello, V; Quel, E J; Querchfeld, S; Quinn, S; Rautenberg, J; Ravel, O; Ravignani, D; Revenu, B; Ridky, J; Riggi, S; Risse, M; Ristori, P; Rizi, V; Roberts, J; Rodrigues, W; Rodriguez, I; Rodriguez, G; Rodriguez, J; Rodríguez-Frías, M D; Ros, G; Rosado, J; Rossler, T; Roth, M; Roulet, E; Rovero, A C; Saffi, S J; Saftoiu, A; Salamida, F; Salazar, H; Saleh, A; Salesa, F; Salina, G; Sánchez, F; Sanchez-Lucas, P; Santo, C E; Santos, E; Santos, E M; Sarazin, F; Sarkar, B; Sarmento, R; Sato, R; Scharf, N; Scherini, V; Schieler, H; Schiffer, P; Scholten, O; Schoorlemmer, H; Schovánek, P; Schulz, A; Schulz, J; Schumacher, J; Sciutto, S J; Segreto, A; Settimo, M; Shadkam, A; Shellard, R C; Sidelnik, I; Sigl, G; Sima, O; Śmiał, A; Šmída, R; Snow, G R; Sommers, P; Sorokin, J; Squartini, R; Srivastava, Y N; Stanič, S; Stapleton, J; Stasielak, J; Stephan, M; Stutz, A; Suarez, F; Suomijärvi, T; Supanitsky, A D; Sutherland, M S; Swain, J; Szadkowski, Z; Szuba, M; Taborda, O A; Tapia, A; Tartare, M; Theodoro, V M; Timmermans, C; Todero, C J; Toma, G; Tomankova, L; Tomé, B; Tonachini, A; Torralba, G; Torres, D; Travnicek, P; Trovato, E; Tueros, M; Ulrich, R; Unger, M; Urban, M; Valdés, J F; Valiño, I; Valore, L; van, G; van, A M; van, S; van, A; Varela, E; Vargas, B; Varner, G; Vázquez, J R; Vázquez, R A; Veberič, D; Verzi, V; Vicha, J; Videla, M; Villaseñor, L; Vlcek, B; Vorobiov, S; Wahlberg, H; Wainberg, O; Walz, D; Watson, A A; Weber, M; Weidenhaupt, K; Weindl, A; Werner, F; Widom, A; Wiencke, L; Wilczyńska, B; Wilczyński, H; Will, M; Williams, C; Winchen, T; Wittkowski, D; Wundheiler, B; Wykes, S; Yamamoto, T; Yapici, T; Younk, P; Yuan, G; Yushkov, A; Zamorano, B; Zas, E; Zavrtanik, D; Zavrtanik, M; Zaw, I; Zepeda, A; Zhou, J; Zhu, Y; Zimbres, M; Ziolkowski, M; Abbasi, R U; Abe, M; Abu-Zayyad, T; Allen, M; Anderson, R; Azuma, R; Barcikowski, E; Belz, J W; Bergman, D R; Blake, S A; Cady, R; Chae, M J; Cheon, B G; Chiba, J; Chikawa, M; Cho, W R; Fujii, T; Fukushima, M; Goto, T; Hanlon, W; Hayashi, Y; Hayashida, N; Hibino, K; Honda, K; Ikeda, D; Inoue, N; Ishii, T; Ishimori, R; Ito, H; Ivanov, D; Jui, C C H; Kadota, K; Kakimoto, F; Kalashev, O; Kasahara, K; Kawai, H; Kawakami, S; Kawana, S; Kawata, K; Kido, E; Kim, H B; Kim, J H; Kitamura, S; Kitamura, Y; Kuzmin, V; Kwon, Y J; Lan, J; Lim, S I; Lundquist, J P; Machida, K; Martens, K; Matsuda, T; Matsuyama, T; Matthews, J N; Minamino, M; Mukai, K; Myers, I; Nagasawa, K; Nagataki, S; Nakamura, T; Nonaka, T; Nozato, A; Ogio, S; Ogura, J; Ohnishi, M; Ohoka, H; Oki, K; Okuda, T; Ono, M; Oshima, A; Ozawa, S; Park, I H; Pshirkov, M S; Rodriguez, D C; Rubtsov, G; Ryu, D; Sagawa, H; Sakurai, N; Sampson, A L; Scott, L M; Shah, P D; Shibata, F; Shibata, T; Shimodaira, H; Shin, B K; Smith, J D; Sokolsky, P; Springer, R W; Stokes, B T; Stratton, S R; Stroman, T A; Suzawa, T; Takamura, M; Takeda, M; Takeishi, R; Taketa, A; Takita, M; Tameda, Y; Tanaka, H; Tanaka, K; Tanaka, M; Thomas, S B; Thomson, G B; Tinyakov, P; Tkachev, I; Tokuno, H; Tomida, T; Troitsky, S; Tsunesada, Y; Tsutsumi, K; Uchihori, Y; Udo, S; Urban, F; Vasiloff, G; Wong, T; Yamane, R; Yamaoka, H; Yamazaki, K; Yang, J; Yashiro, K; Yoneda, Y; Yoshida, S; Yoshii, H; Zollinger, R; Zundel, Z

    2014-01-01

    Spherical harmonic moments are well-suited for capturing anisotropy at any scale in the flux of cosmic rays. An unambiguous measurement of the full set of spherical harmonic coefficients requires full-sky coverage. This can be achieved by combining data from observatories located in both the northern and southern hemispheres. To this end, a joint analysis using data recorded at the Telescope Array and the Pierre Auger Observatory above $10^{19}$ eV is presented in this work. The resulting multipolar expansion of the flux of cosmic rays allows us to perform a series of anisotropy searches, and in particular to report on the angular power spectrum of cosmic rays above $10^{19}$ eV. No significant deviation from isotropic expectations is found throughout the analyses performed. Upper limits on the amplitudes of the dipole and quadrupole moments are derived as a function of the direction in the sky, varying between 7% and 13% for the dipole and between 7% and 10% for a symmetric quadrupole.

  6. The Energy Spectrum of Telescope Array's Middle Drum Detector and the Direct Comparison to the High Resolution Fly's Eye Experiment

    OpenAIRE

    Abu-Zayyad, T.; Aida, R.; Allen, M.; Anderson, R; Azuma, R.; Barcikowski, E.; Belz, J. W.; Bergman, D. R.; Blake, S. A.; Cady, R.; B.G. Cheon; Chiba, J.; Chikawa, M.; Cho, E. J.; Cho, W. R.

    2012-01-01

    The Telescope Array's Middle Drum fluorescence detector was instrumented with telescopes refurbished from the High Resolution Fly's Eye's HiRes-1 site. The data observed by Middle Drum in monocular mode was analyzed via the HiRes-1 profile-constrained geometry reconstruction technique and utilized the same calibration techniques enabling a direct comparison of the energy spectra and energy scales between the two experiments. The spectrum measured using the Middle Drum telescopes is based on a...

  7. A simple setup to measure muon lifetime and electron energy spectrum of muon decay and its Monte Carlo simulation

    CERN Document Server

    Hu, Yushi; Mei, Yefeng; Zhang, Zhao; Ning, Chuangang

    2016-01-01

    We designed a simple setup to measure the muon lifetime and the electron energy spectra of muon decay. A low cost coincidental circuit was designed to select the signals of muon decay events detected by a plastic scintillator detector. It triggered a digital oscilloscope to record the signals of muon decay events for measuring the muon lifetime and electron energy spectrum. A Landau-distribution energy loss method was introduced to conduct the energy calibration of the system. The experimental results were well reproduced by the Monte Carlo simulation. The software and hardware of the system are completely open to students, thus more helpful for instruction and motivation.

  8. Interplay between anisotropy and spatial dispersion in metamaterial waveguide

    CERN Document Server

    Koshelev, Kirill L

    2016-01-01

    We analyze spectrum of waveguide modes of an arbitrary uniaxial anisotropic metamaterial slab with non-local electromagnetic response whose permittivity tensor could be described within Drude approximation. Spatial dispersion was introduced within the hydrodynamical model. Both anisotropy and spatial dispersion were considered as perturbations. This helps to distinguish their effect on the spectrum of the slab and to analyze lifting of the degeneracy of eigenmodes at plasma frequency in detail. Spatial dispersion is shown to result in break of the singularity in the den- sity of optical states in the hyperbolic regime and in suppression of negative dispersion induced by anisotropy. Mutual effect of spatial dispersion and anisotropy can bring light to a complete stop at certain frequencies.

  9. Kolmogorov constants for the second-order structure function and the energy spectrum.

    Science.gov (United States)

    Ni, Rui; Xia, Ke-Qing

    2013-02-01

    We examine the behavior of the Kolmogorov constants C(2), C(k), and C(k1), which are, respectively, the prefactors of the second-order longitudinal structure function and the three-dimensional and one-dimensional longitudinal energy spectrum in the inertial range. We show that their ratios, C(2)/C(k1) and C(k)/C(k1), exhibit clear dependence on the microscale Reynolds number R(λ), implying that they cannot all be independent of R(λ). In particular, it is found that (C(k1)/C(2)-0.25)=1.95R(λ)(-0.68). The study further reveals that the widely used relation C(2)=4.02C(k1) holds only asymptotically when R(λ)>/~10(5). It is also found that C(2) has much stronger R(λ) dependence than either C(k) or C(k1) if the latter indeed has a systematic dependence on R(λ). We further show that the varying dependence on R(λ) of these three numbers can be attributed to the difference of the inertial range in real- and wave-number space, with the inertial range in real-space known to be much shorter than that in wave-number space.

  10. The infrared properties of the energy spectrum in freely decaying isotropic turbulence

    CERN Document Server

    McComb, W D

    2014-01-01

    The low wavenumber expansion of the energy spectrum takes the well known form: $ E(k,t) = E_2(t) k^2 + E_4(t) k^4 + ... $, where the coefficients are weighted integrals against the correlation function $C(r,t)$. We show that expressing $E(k,t)$ in terms of the longitudinal correlation function $f(r,t)$ immediately yields $E_2(t)=0$ by cancellation. We verify that the same result is obtained using the correlation function $C(r,t)$, provided only that $f(r,t)$ falls off faster than $r^{-3}$ at large values of $r$. As power-law forms are widely studied for the purpose of establishing bounds, we consider the family of model correlations $f(r,t)=\\alpha_n(t)r^{-n}$, for positive integer $n$, at large values of the separation $r$. We find that for the special case $n=3$, the relationship connecting $f(r,t)$ and $C(r,t)$ becomes indeterminate, and (exceptionally) $E_2 \

  11. Combined diversity and improved energy detection in cooperative spectrum sensing with faded reporting channels

    Directory of Open Access Journals (Sweden)

    Srinivas Nallagonda

    2016-04-01

    Full Text Available In this paper we evaluate the performance of cooperative spectrum sensing (CSS where each cognitive radio (CR employs an improved energy detector (IED with multiple antennas and uses selection combining (SC for detecting the primary user (PU in noisy and faded sensing (S channels. We derive an expression for the probability of false alarm and expressions for probability of missed detection in non-faded (AWGN and Rayleigh faded sensing environments in terms of cumulative distribution function (CDF. Each CR transmits its decision about PU via noisy and faded reporting (R channel to fusion center (FC. In this paper we assume that S-channels are noisy and Rayleigh faded while several cases of fading are considered for R-channels such as: (i Hoyt (or Nakagami-q, (ii Rayleigh, (iii Rician (or Nakagami-n, and (iv Weibull. A Binary Symmetric channel (BSC with a fixed error probability (r in the R-channel is also considered. The impact of fading in R-channel, S-channel and several network parameters such as IED parameter, normalized detection threshold, number of CRs, and number of antennas on missed detection and total error probability is assessed. The effects of Hoyt, Rician, and Weibull fading parameters on overall performance of IED-CSS are also highlighted.

  12. Research on seasonal correlation of wavelet packet energy spectrum and temperature of Runyang Suspension Bridge

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    In order to establish an environmental-condition-normalized structural damage alarming method,the seasonal correlation analysis of wavelet packet energy spectrum(WPES)and temperature of Runyang Suspension Bridge is performed by means of the 236-day health monitoring data.The analysis results reveal that the measured WPES has remarkable seasonal correlation with the environmental tempera-ture.The seasonal change of environmental temperature accounts for the variation of the damage alarming parameter Ip of the dominant frequency bands with an averaged variance of 200%.The statis-tical modeling technique using a 6th-order polynomial is adopted to formulate the correlation between the WPES and temperature,on the basis of which the abnormal changes of measured damage alarming parameter Ip are detected using the mean value control chart.It is found that the proposed method can effectively eliminate temperature complications from the time series of WPES and exhibit good capa-bility for detecting the damage-induced 10% variances of the damage alarming parameter Ip.And the proposed WPES-based method is superior the modal frequency and hence is more suitable for online real-time damage alarming for long-span bridges.

  13. ORIGIN OF COBALT ANISOTROPY IN RARE EARTH-COBALT INTERMETALLICS

    OpenAIRE

    Ballou, Rafik; Lemaire, R.

    1988-01-01

    The strong cobalt anisotropies in rare earth-cobalt intermetallics are shown to arise from orbitally selective 3d band energy dispersion due to either chain like or layered like cobalt staking rather than from usual crystal field effect.

  14. Anisotropies in the diffuse gamma-ray background measured by the Fermi LAT

    CERN Document Server

    Ackermann, M

    2012-01-01

    The contribution of unresolved sources to the diffuse gamma-ray background could induce anisotropies in this emission on small angular scales. We analyze the angular power spectrum of the diffuse emission measured by the Fermi LAT at Galactic latitudes |b| > 30 deg in four energy bins spanning 1 to 50 GeV. At multipoles \\ell \\ge 155, corresponding to angular scales \\lesssim 2 deg, angular power above the photon noise level is detected at >99.99% CL in the 1-2 GeV, 2-5 GeV, and 5-10 GeV energy bins, and at >99% CL at 10-50 GeV. Within each energy bin the measured angular power takes approximately the same value at all multipoles \\ell \\ge 155, suggesting that it originates from the contribution of one or more unclustered source populations. The amplitude of the angular power normalized to the mean intensity in each energy bin is consistent with a constant value at all energies, C_P/^2 = 9.05 +/- 0.84 x 10^{-6} sr, while the energy dependence of C_P is consistent with the anisotropy arising from one or more sour...

  15. Energy spectrum and specific heat of two-dimensional electron systems with spin-orbit interaction in a magnetic field parallel to the conducting layer

    Science.gov (United States)

    Shevchenko, O. S.; Kopeliovich, A. I.

    2016-03-01

    The energy spectrum of a quasi-two-dimensional electron gas in an in-plane magnetic field is studied using the perturbation theory and quasiclassical approach in the presence of the Rashba and Dresselhaus spin-orbit coupling. The existence of the intersection of energy sublevels in electron spectrum is demonstrated. The reciprocal mass tensor of electrons is analyzed. The heat capacity of the degenerate electron gas is examined, and its relations with the key features of the spectrum are shown.

  16. Correlation between peak energy and Fourier power density spectrum slope in gamma-ray bursts

    Science.gov (United States)

    Dichiara, S.; Guidorzi, C.; Amati, L.; Frontera, F.; Margutti, R.

    2016-05-01

    Context. The origin of the gamma-ray burst (GRB) prompt emission still defies explanation, in spite of recent progress made, for example, on the occasional presence of a thermal component in the spectrum along with the ubiquitous non-thermal component that is modelled with a Band function. The combination of finite duration and aperiodic modulations make GRBs hard to characterise temporally. Although correlations between GRB luminosity and spectral hardness on one side and time variability on the other side have long been known, the loose and often arbitrary definition of the latter makes the interpretation uncertain. Aims: We characterise the temporal variability in an objective way and search for a connection with rest-frame spectral properties for a number of well-observed GRBs. Methods: We studied the individual power density spectra (PDS) of 123 long GRBs with measured redshift, rest-frame peak energy Ep,i of the time-averaged ν Fν spectrum, and well-constrained PDS slope α detected with Swift, Fermi and past spacecraft. The PDS were modelled with a power law either with or without a break adopting a Bayesian Markov chain Monte Carlo technique. Results: We find a highly significant Ep,i-α anti-correlation. The null hypothesis probability is ~10-9. Conclusions: In the framework of the internal shock synchrotron model, the Ep,i-α anti-correlation can hardly be reconciled with the predicted Ep,i ∝ Γ-2, unless either variable microphysical parameters of the shocks or continual electron acceleration are assumed. Alternatively, in the context of models based on magnetic reconnection, the PDS slope and Ep,i are linked to the ejecta magnetisation at the dissipation site, so that more magnetised outflows would produce more variable GRB light curves at short timescales (≲1 s), shallower PDS, and higher values of Ep,i. Full Table 1 is only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc

  17. Polarization and dilepton anisotropy in pion-nucleon collisions

    CERN Document Server

    Speranza, Enrico; Friman, Bengt

    2016-01-01

    Hadronic polarization and the related anisotropy of the dilepton angular distribution are studied for the reaction $\\pi N \\rightarrow Ne^+ e^-$. We employ consistent effective interactions for baryon resonances up to spin-5/2, where non-physical degrees of freedom are eliminated, to compute the anisotropy coefficients for isolated intermediate baryon resonances. It is shown that the spin and parity of the intermediate baryon resonance is reflected in the angular dependence of the anisotropy coefficient. We then compute the anisotropy coefficient including the $N(1520)$ and $N(1440)$ resonances, which are essential at the collision energy of the recent data obtained by the HADES collaboration on this reaction. We conclude that the anisotropy coefficient provides useful constraints for unravelling the resonance contributions to this process.

  18. Measurement of the Electron Energy Spectrum and its Moments in Inclusive B->X e nu Decays

    CERN Document Server

    Aubert, B; Boutigny, D; Couderc, F; Gaillard, J M; Hicheur, A; Karyotakis, Yu; Lees, J P; Tisserand, V; Zghiche, A; Palano, A; Pompili, A; Chen, J C; Qi, N D; Rong, G; Wang, P; Zhu, Y S; Eigen, G; Ofte, I; Stugu, B; Abrams, G S; Borgland, A W; Breon, A B; Brown, D N; Button-Shafer, J; Cahn, R N; Charles, E; Day, C T; Gill, M S; Gritsan, A V; Groysman, Y; Jacobsen, R G; Kadel, R W; Kadyk, J; Kerth, L T; Kolomensky, Yu G; Kukartsev, G; Le Clerc, C; Levi, M E; Lynch, G; Mir, L M; Oddone, P J; Orimoto, T J; Pripstein, M; Roe, N A; Ronan, Michael T; Shelkov, V G; Telnov, A V; Wenzel, W A; Ford, K; Harrison, T J; Hawkes, C M; Morgan, S E; Watson, A T; Watson, N K; Fritsch, M; Goetzen, K; Held, T; Koch, H; Lewandowski, B; Pelizaeus, M; Steinke, M; Boyd, J T; Chevalier, N; Cottingham, W N; Kelly, M P; Latham, T E; Wilson, F F; Abe, K; Çuhadar-Dönszelmann, T; Hearty, C; Mattison, T S; McKenna, J A; Thiessen, D; Kyberd, P; Teodorescu, L; Blinov, V E; Bukin, A D; Druzhinin, V P; Golubev, V B; Ivanchenko, V N; Kravchenko, E A; Onuchin, A P; Serednyakov, S I; Skovpen, Yu I; Solodov, E P; Yushkov, A N; Best, D; Bruinsma, M; Chao, M; Eschrich, I; Kirkby, D; Lankford, A J; Mandelkern, M A; Mommsen, R K; Röthel, W; Stoker, D P; Buchanan, C; Hartfiel, B L; Gary, J W; Shen, B C; Wang, K; Del Re, D; Hadavand, H K; Hill, E J; MacFarlane, D B; Paar, H P; Rahatlou, S; Sharma, V; Berryhill, J W; Campagnari, C; Dahmes, B; Levy, S L; Long, O; Lu, A; Mazur, M A; Richman, J D; Verkerke, W; Beck, T W; Eisner, A M; Heusch, C A; Lockman, W S; Schalk, T; Schmitz, R E; Schumm, B A; Seiden, A; Spradlin, P; Williams, D C; Wilson, M G; Albert, J; Chen, E; Dubois-Felsmann, G P; Dvoretskii, A; Hitlin, D G; Narsky, I; Piatenko, T; Porter, F C; Ryd, A; Samuel, A; Yang, S; Jayatilleke, S M; Mancinelli, G; Meadows, B T; Sokoloff, M D; Abe, T; Blanc, F; Bloom, P; Chen, S; Clark, P J; Ford, W T; Nauenberg, U; Olivas, A; Rankin, P; Smith, J G; Van Hoek, W C; Zhang, L; Harton, J L; Hu, T; Soffer, A; Toki, W H; Wilson, R J; Altenburg, D; Brandt, T; Brose, J; Colberg, T; Dickopp, M; Feltresi, E; Hauke, A; Lacker, H M; Maly, E; Müller-Pfefferkorn, R; Nogowski, R; Otto, S; Schubert, J; Schubert, Klaus R; Schwierz, R; Spaan, B; Bernard, D; Bonneaud, G R; Brochard, F; Grenier, P; Thiebaux, C; Vasileiadis, G; Verderi, M; Bard, D J; Khan, A; Lavin, D; Muheim, F; Playfer, S; Andreotti, M; Azzolini, V; Bettoni, D; Bozzi, C; Calabrese, R; Cibinetto, G; Luppi, E; Negrini, M; Sarti, A; Treadwell, E; Baldini-Ferroli, R; Calcaterra, A; De Sangro, R; Finocchiaro, G; Patteri, P; Piccolo, M; Zallo, A; Buzzo, A; Capra, R; Contri, R; Crosetti, G; Lo Vetere, M; Macri, M; Monge, M R; Passaggio, S; Patrignani, C; Robutti, E; Santroni, A; Tosi, S; Bailey, S; Brandenburg, G; Morii, M; Won, E; Dubitzky, R S; Langenegger, U; Bhimji, W; Bowerman, D A; Dauncey, P D; Egede, U; Gaillard, J R; Morton, G W; Nash, J A; Taylor, G P; Grenier, G J; Lee, S J; Mallik, U; Cochran, J; Crawley, H B; Lamsa, J; Meyer, W T; Prell, S; Rosenberg, E I; Yi, J; Davier, M; Grosdidier, G; Höcker, A; Laplace, S; Le Diberder, F R; Lepeltier, V; Lutz, A M; Petersen, T C; Plaszczynski, S; Schune, M H; Tantot, L; Wormser, G; Cheng, C H; Lange, D J; Simani, M C; Wright, D M; Bevan, A J; Coleman, J P; Fry, J R; Gabathuler, Erwin; Gamet, R; Kay, M; Parry, R J; Payne, D J; Sloane, R J; Touramanis, C; Back, J J; Harrison, P F; Mohanty, G B; Brown, C L; Cowan, G; Flack, R L; Flächer, H U; George, S; Green, M G; Kurup, A; Marker, C E; McMahon, T R; Ricciardi, S; Salvatore, F; Vaitsas, G; Winter, M A; Brown, D; Davis, C L; Allison, J; Barlow, N R; Barlow, R J; Hart, P A; Hodgkinson, M C; Lafferty, G D; Lyon, A J; Williams, J C; Farbin, A; Hulsbergen, W D; Jawahery, A; Kovalskyi, D; Lae, C K; Lillard, V; Roberts, D A; Blaylock, G; Dallapiccola, C; Flood, K T; Hertzbach, S S; Kofler, R; Koptchev, V B; Moore, T B; Saremi, S; Stängle, H; Willocq, S; Cowan, R; Sciolla, G; Taylor, F; Yamamoto, R K; Mangeol, D J J; Patel, P M; Robertson, S H; Lazzaro, A; Palombo, F; Bauer, J M; Cremaldi, L M; Eschenburg, V; Godang, R; Kroeger, R; Reidy, J; Sanders, D A; Summers, D J; Zhao, H W; Brunet, S; Côté, D; Taras, P; Nicholson, H; Cartaro, C; Cavallo, N; Fabozzi, F; Gatto, C; Lista, L; Monorchio, D; Paolucci, P; Piccolo, D; Sciacca, C; Baak, M; Raven, G; Wilden, L; Jessop, C P; LoSecco, J M; Gabriel, T A; Allmendinger, T; Brau, B; Gan, K K; Honscheid, K; Hufnagel, D; Kagan, H; Kass, R; Pulliam, T; Ter-Antonian, R; Wong, Q K; Brau, J E; Frey, R; Igonkina, O; Potter, C T; Sinev, N B; Strom, D; Torrence, E; Colecchia, F; Dorigo, A; Galeazzi, F; Margoni, M; Morandin, M; Posocco, M; Rotondo, M; Simonetto, F; Stroili, R; Tiozzo, G; Voci, C; Benayoun, M; Briand, H; Chauveau, J; David, P; La Vaissière, C de; Del Buono, L; Hamon, O; John, M J J; Leruste, P; Ocariz, J; Pivk, M; Roos, L; T'Jampens, S; Therin, G; Manfredi, P F; Re, V; Behera, P K; Gladney, L; Guo, Q H; Panetta, J; Anulli, F; Biasini, M; Peruzzi, I M; Pioppi, M; Angelini, C; Batignani, G; Bettarini, S; Bondioli, M; Bucci, F; Calderini, G; Carpinelli, M; Del Gamba, V; Forti, F; Giorgi, M A; Lusiani, A; Marchiori, G; Martínez-Vidal, F; Morganti, M; Neri, N; Paoloni, E; Rama, M; Rizzo, G; Sandrelli, F; Walsh, J; Haire, M; Judd, D; Paick, K; Wagoner, D E; Danielson, N; Elmer, P; Lü, C; Miftakov, V; Olsen, J; Smith, A J S; Varnes, E W; Bellini, F; Cavoto, G; Faccini, R; Ferrarotto, F; Ferroni, F; Gaspero, M; Li Gioi, L; Mazzoni, M A; Morganti, S; Pierini, M; Piredda, G; Safai-Tehrani, F; Voena, C; Christ, S; Wagner, G; Waldi, R; Adye, T; De Groot, N; Franek, B J; Geddes, N I; Gopal, G P; Olaiya, E O; Xella, S M; Aleksan, Roy; Emery, S; Gaidot, A; Ganzhur, S F; Giraud, P F; Hamel de Monchenault, G; Kozanecki, Witold; Langer, M; Legendre, M; London, G W; Mayer, B; Schott, G; Vasseur, G; Yéche, C; Zito, M; Purohit, M V; Weidemann, A W; Yumiceva, F X; Aston, D; Bartoldus, R; Berger, N; Boyarski, A M; Buchmüller, O L; Convery, M R; Cristinziani, M; De Nardo, Gallieno; Dong, D; Dorfan, J; Dujmic, D; Dunwoodie, W M; Elsen, E E; Field, R C; Glanzman, T; Gowdy, S J; Hadig, T; Halyo, V; Hrynóva, T; Innes, W R; Kelsey, M H; Kim, P; Kocian, M L; Leith, D W G S; Libby, J; Luitz, S; Lüth, V; Lynch, H L; Marsiske, H; Messner, R; Müller, D R; O'Grady, C P; Ozcan, V E; Perazzo, A; Perl, M; Petrak, S; Ratcliff, B N; Roodman, A; Salnikov, A A; Schindler, R H; Schwiening, J; Simi, G; Snyder, A; Soha, A; Stelzer, J; Su, D; Sullivan, M K; Vavra, J; Wagner, S R; Weaver, M; Weinstein, A J R; Wisniewski, W J; Wittgen, M; Wright, D H; Young, C C; Burchat, Patricia R; Edwards, A J; Meyer, T I; Petersen, B A; Roat, C; Ahmed, S; Alam, M S; Ernst, J A; Saeed, M A; Saleem, M; Wappler, F R; Bugg, W; Krishnamurthy, M; Spanier, S M; Eckmann, R; Kim, H; Ritchie, J L; Satpathy, A; Schwitters, R F; Izen, J M; Kitayama, I; Lou, X C; Ye, S; Bianchi, F; Bóna, M; Gallo, F; Gamba, D; Borean, C; Bosisio, L; Cossutti, F; Della Ricca, G; Dittongo, S; Grancagnolo, S; Lanceri, L; Poropat, P; Vitale, L; Vuagnin, G; Panvini, R S; Banerjee, Sw; Brown, C M; Fortin, D; Jackson, P D; Kowalewski, R V; Roney, J M; Band, H R; Dasu, S; Datta, M; Eichenbaum, A M; Hollar, J J; Johnson, J R; Kutter, P E; Li, H; Liu, R; Di Lodovico, F; Mihályi, A; Mohapatra, A K; Pan, Y; Prepost, R; Sekula, S J; Tan, P; Von Wimmersperg-Töller, J H; Wu, J; Wu, S L; Yu, Z; Neal, H

    2004-01-01

    We report a measurement of the inclusive electron energy spectrum for semileptonic decays of B mesons in a data sample of 52 million Y4S -> BBar decays collected with the BABAR detector at the PEP-II asymmetric-energy B-meson factory at SLAC. We determine the branching fraction, first, second, and third moments of the spectrum for lower cut-offs on the electron energy between 0.6 and 1.5 GeV. We measure the partial branching fraction to be Br(B -> X e nu, E_e>0.6 GeV) = (10.36 +-0.06(stat.) +-0.23(sys))%.

  19. Cosmic ray energy spectrum measurement with the Antarctic Muon and Neutrino Detector Array (AMANDA)

    Science.gov (United States)

    Chirkin, Dmitry Aleksandrovich

    AMANDA-II is a neutrino telescope composed of 677 optical sensors organized along 19 strings buried deep in the Antarctic ice cap. It is designed to detect Cherenkov light produced by cosmic-ray- and neutrino-induced charged leptons. The majority of events recorded by AMANDA-II are caused by muons which are produced in the atmosphere by high-energy cosmic rays. The leading uncertainties in simulating such events come from the choice of the high-energy model used to describe the first interaction of the cosmic rays, uncertainties in our knowledge and implementation of the ice properties at the depth of the detector, and individual optical module sensitivities. Contributions from uncertainties in the atmospheric conditions and muon cross sections in ice are smaller. The downgoing muon simulation was substantially improved by using the extensive air shower generator CORSIKA to describe the shower development in the atmosphere, and by writing a new software package for the muon propagation (MMC), which reduced computational and algorithm errors below the level of uncertainties of the muon cross sections in ice. A method was developed that resulted in a flux measurement of cosmic rays with energies 1.5--200 TeV per nucleon (95% of primaries causing low-multiplicity events in AMANDA-II have energies in this range) independent of ice model and optical module sensitivities. Predictions of six commonly used high-energy interaction models (QGSJET, VENUS, NEXUS, DPMJET, HDPM, and SIBYLL) are compared to data. The best agreement with direct measurements is achieved with QGSJET, VENUS, and NEXUS. Assuming a power-law energy spectrum (phi0,i · E -gammai) for cosmic-ray components from hydrogen to iron (i = H,..., Fe) and their mass distribution according to Wiebel-South (Wiebel-South & Biermann, 1999), phi 0,i and gammai were corrected to achieve the best description of the data. For the hydrogen component, values of phi0,H = 0.106 +/- 0.007 m-2 sr-1s-1TeV-1 , gammaH = 2

  20. Determination of neutron energy spectrum at a pneumatic rabbit station of a typical swimming pool type material test research reactor

    International Nuclear Information System (INIS)

    The method of multiple foil activation was used to measure the neutron energy spectrum, experimentally, at a rabbit station of Pakistan Research Reactor-1 (PARR-1), which is a typical swimming pool type material test research reactor. The computer codes MSITER and SANDBP were used to adjust the spectrum. The pre-information required by the adjustment codes was obtained by modelling the core and its surroundings in three-dimensions by using the one dimensional transport theory code WIMS-D/4 and the multidimensional finite difference diffusion theory code CITATION. The input spectrum covariance information required by MSITER code was also calculated from the CITATION output. A comparison between calculated and adjusted spectra shows a good agreement

  1. Two-dimensional angular energy spectrum of electrons accelerated by the ultra-short relativistic laser pulse

    Energy Technology Data Exchange (ETDEWEB)

    Borovskiy, A. V. [Department of Computer Science and Cybernetics, Baikal State University of Economics and Law, 11 Lenin Street, Irkutsk 664003 (Russian Federation); Galkin, A. L. [Coherent and Nonlinear Optics Department, A.M. Prokhorov General Physics Institute of the RAS, 38 Vavilov Street, Moscow 119991 (Russian Federation); Department of Physics of MBF, Pirogov Russian National Research Medical University, 1 Ostrovitianov Street, Moscow 117997 (Russian Federation); Kalashnikov, M. P., E-mail: galkin@kapella.gpi.ru [Max-Born-Institute for Nonlinear Optics and Short-Time Spectroscopy, 2a Max-Born-Strasse, Berlin 12489 (Germany)

    2015-04-15

    The new method of calculating energy spectra of accelerated electrons, based on the parameterization by their initial coordinates, is proposed. The energy spectra of electrons accelerated by Gaussian ultra-short relativistic laser pulse at a selected angle to the axis of the optical system focusing the laser pulse in a low density gas are theoretically calculated. The two-peak structure of the electron energy spectrum is obtained. Discussed are the reasons for its appearance as well as an applicability of other models of the laser field.

  2. Energy Dependence of Near-relativistic Electron Spectrum at Geostationary Orbit during the SEP Events of 2005

    Indian Academy of Sciences (India)

    A. Chandrasekhar Reddy; Jatin Rathod; Girija Rajaram; Radharani Alyana; D. S. Misra; C. G. Patil; M. Y. S. Prasad; A. G. Ananth

    2008-03-01

    In view of the renewed interest in the study of energetic particles in the outer radiation belt of the earth, we feel it will be helpful in looking for the energy dependence of the electron energy spectrum at geostationary orbit. This may give us some insight into how we can safeguard geostationary satellites from functional anomalies of the deep dielectric charging type, which are caused by charge accumulation and subsequent discharge of relativistic electrons. In this study we examine whether there is any energy dependence in relativistic electron enhancements at geosynchronous altitudes during solar energetic proton events of 2005.

  3. Low-temperature magnetization anisotropy in ferromagnetic materials with quenched orbital angular momentum

    Energy Technology Data Exchange (ETDEWEB)

    Rozenfel`d, E.V.; Korolev, A.V. [Inst. of Metal Physics, Ekaterinburg (Russian Federation)

    1995-09-01

    A phenomenological theory of magnetic anisotropy and low-temperature magnetization anisotropy, which arise because of anisotropic quenching of the orbital angular momentum, is constructed. A relation is found between the parameters of the theory and the electronic spectrum of the magnetic material. It is shown that for magnetic materials whose magnetic anisotropy is of this origin the spin-orbit interaction energy and the spin and orbital contributions to the magnetization and susceptibility of the paraprocess can be determined form the magnetization curves in the {open_quotes}easy{close_quotes} and {open_quotes}difficult{close_quotes} directions. The application of the theory to pure Co and to some intermetallic compounds of the type RCo{sub 5}, where R = Y, La, Ce, and Th, is examined. The values obtained for the spin-orbit coupling constant per cobalt atom are close to the values known for 3d-metal ions and the values obtained for the spin and orbital magnetic moments agree with the values obtained by neutron diffractometry for Co and YCo{sub 5}. 25 refs., 1 fig., 2 tabs.

  4. Dark matter electron anisotropy. A universal upper limit

    Energy Technology Data Exchange (ETDEWEB)

    Borriello, Enrico [Universita ' ' Federico II' ' , Napoli (Italy). Dipt. di Scienze Fisiche; INFN, Sezione di Napoli (Italy); Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Maccione, Luca [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Cuoco, Alessandro [Oskar Klein Centre for Cosmoparticle Physics, Stockholm (Sweden)

    2010-12-15

    Indirect searches of particle Dark Matter (DM) with high energy Cosmic Rays (CR) are affected by large uncertainties, coming both from the DM side, and from poor understanding of the astrophysical backgrounds. We show that, on the contrary, the DM intrinsic degree of anisotropy in the arrival directions of high energy CR electrons and positrons does not suffer from these unknowns. Furthermore, if contributions from possible local sources are neglected, the intrinsic DM anisotropy sets the maximum degree of total anisotropy. As a consequence, if some anisotropy larger than the DM upper bound is detected, its origin could not be ascribed to DM, and would constitute an unambiguous evidence for the presence of astrophysical local discrete sources of high energy electrons and positrons. The Fermi-LAT will be able to probe such scenarios in the next years. (orig.)

  5. Flow stress anisotropy

    DEFF Research Database (Denmark)

    Winther, G.

    1996-01-01

    stress Variation in the rolling plane, which may be as high as 20%, are presented. The traditional Taylor model is applied to the data to account for the effect of texture. However, texture effects alone are not enough to explain all of the observed anisotropy. New models which take the combined effects...... of texture and deformation microstructure into account are presented. The models are based on the Taylor and Sachs models but modified with an anisotropic critical shear stress to account for the effect of the microstructure. The agreement between experimental data and model predictions is definitely better...

  6. The Energy Spectrum of Telescope Array's Middle Drum Detector and the Direct Comparison to the High Resolution Fly's Eye Experiment

    CERN Document Server

    Abu-Zayyad, T; Allen, M; Anderson, R; Azuma, R; Barcikowski, E; Belz, J W; Bergman, D R; Blake, S A; Cady, R; Cheon, B G; Chiba, J; Chikawa, M; Cho, E J; Cho, W R; Fujii, H; Fujii, T; Fukuda, T; Fukushima, M; Gorbunov, D; Hanlon, W; Hayashi, K; Hayashi, Y; Hayashida, N; Hibino, K; Hiyama, K; Honda, K; Iguchi, T; Ikeda, D; Ikuta, K; Inoue, N; Ishii, T; Ishimori, R; Ivanov, D; Iwamoto, S; Jui, C C H; Kadota, K; Kakimoto, F; Kalashev, O; Kanbe, T; Kasahara, K; Kawai, H; Kawakami, S; Kawana, S; Kido, E; Kim, H B; Kim, H K; Kim, J H; Kim, J H; Kitamoto, K; Kitamura, S; Kitamura, Y; Kobayashi, K; Kobayashi, Y; Kondo, Y; Kuramoto, K; Kuzmin, V; Kwon, Y J; Lim, S I; Machida, S; Martens, K; Martineau, J; Matsuda, T; Matsuura, T; Matsuyama, T; Matthews, J N; Minamino, M; Miyata, K; Murano, Y; Nagataki, S; Nakamura, T; Nam, S W; Nonaka, T; Ogio, S; Ohnishi, M; Ohoka, H; Oki, K; Oku, D; Okuda, T; Oshima, A; Ozawa, S; Park, I H; Pshirkov, M S; Rodriguez, D C; Roh, S Y; Rubtsov, G; Ryu, D; Sagawa, H; Sakurai, N; Sampson, A L; Scott, L M; Shah, P D; Shibata, F; Shibata, T; Shimodaira, H; Shin, B K; Shin, J I; Shirahama, T; Smith, J D; Sokolsky, P; Sonley, T J; Springer, R W; Stokes, B T; Stratton, S R; Stroman, T; Suzuki, S; Takahashi, Y; Takeda, M; Taketa, A; Takita, M; Tameda, Y; Tanaka, H; Tanaka, K; Tanaka, M; Thomas, S B; Thomson, G B; Tinyakov, P; Tkachev, I; Tokuno, H; Tomida, T; Troitsky, S; Tsunesada, Y; Tsutsumi, K; Tsuyuguchi, Y; Uchihori, Y; Udo, S; Ukai, H; Vasiloff, G; Wada, Y; Wong, T; Wood, M; Yamakawa, Y; Yamane, R; Yamaoka, H; Yamazaki, K; Yang, J; Yoneda, Y; Yoshida, S; Yoshii, H; Zollinger, R; Zundel, Z

    2012-01-01

    The Telescope Array's Middle Drum fluorescence detector was instrumented with telescopes refurbished from the High Resolution Fly's Eye's HiRes-1 site. The data observed by Middle Drum in monocular mode was analyzed via the HiRes-1 profile-constrained geometry reconstruction technique and utilized the same calibration techniques enabling a direct comparison of the energy spectra and energy scales between the two experiments. The spectrum measured using the Middle Drum telescopes is based on a three-year exposure collected between December 16, 2007 and December 16, 2010. The calculated difference between the spectrum of the Middle Drum observations and the published spectrum obtained by the data collected by the HiRes-1 site allows the HiRes-1 energy scale to be transferred to Middle Drum. The HiRes energy scale is applied to the entire Telescope Array by making a comparison between Middle Drum monocular events and hybrid events that triggered both Middle Drum and the Telescope Array's scintillator Ground Arra...

  7. The method for analysing jet azimuthal anisotropy in ultrarelativistic heavy ion collisions

    CERN Document Server

    Lokhtin, Igor P; Snigirev, A M

    2002-01-01

    The azimuthal anisotropy of jet spectra due to energy loss of jet partons in azimuthally non-symmetric volume of dense quark-gluon matter is considered for semi-central nuclear interactions at collider energies. We develop the techniques for event-by-event analysing jet azimuthal anisotropy using particle and energy elliptic flow, and suggest the method for calculating coefficient of jet azimuthal anisotropy without reconstruction of nuclear reaction plane.

  8. An Energy-Efficient Spectrum-Aware Reinforcement Learning-Based Clustering Algorithm for Cognitive Radio Sensor Networks.

    Science.gov (United States)

    Mustapha, Ibrahim; Mohd Ali, Borhanuddin; Rasid, Mohd Fadlee A; Sali, Aduwati; Mohamad, Hafizal

    2015-01-01

    It is well-known that clustering partitions network into logical groups of nodes in order to achieve energy efficiency and to enhance dynamic channel access in cognitive radio through cooperative sensing. While the topic of energy efficiency has been well investigated in conventional wireless sensor networks, the latter has not been extensively explored. In this paper, we propose a reinforcement learning-based spectrum-aware clustering algorithm that allows a member node to learn the energy and cooperative sensing costs for neighboring clusters to achieve an optimal solution. Each member node selects an optimal cluster that satisfies pairwise constraints, minimizes network energy consumption and enhances channel sensing performance through an exploration technique. We first model the network energy consumption and then determine the optimal number of clusters for the network. The problem of selecting an optimal cluster is formulated as a Markov Decision Process (MDP) in the algorithm and the obtained simulation results show convergence, learning and adaptability of the algorithm to dynamic environment towards achieving an optimal solution. Performance comparisons of our algorithm with the Groupwise Spectrum Aware (GWSA)-based algorithm in terms of Sum of Square Error (SSE), complexity, network energy consumption and probability of detection indicate improved performance from the proposed approach. The results further reveal that an energy savings of 9% and a significant Primary User (PU) detection improvement can be achieved with the proposed approach. PMID:26287191

  9. An Energy-Efficient Spectrum-Aware Reinforcement Learning-Based Clustering Algorithm for Cognitive Radio Sensor Networks.

    Science.gov (United States)

    Mustapha, Ibrahim; Mohd Ali, Borhanuddin; Rasid, Mohd Fadlee A; Sali, Aduwati; Mohamad, Hafizal

    2015-08-13

    It is well-known that clustering partitions network into logical groups of nodes in order to achieve energy efficiency and to enhance dynamic channel access in cognitive radio through cooperative sensing. While the topic of energy efficiency has been well investigated in conventional wireless sensor networks, the latter has not been extensively explored. In this paper, we propose a reinforcement learning-based spectrum-aware clustering algorithm that allows a member node to learn the energy and cooperative sensing costs for neighboring clusters to achieve an optimal solution. Each member node selects an optimal cluster that satisfies pairwise constraints, minimizes network energy consumption and enhances channel sensing performance through an exploration technique. We first model the network energy consumption and then determine the optimal number of clusters for the network. The problem of selecting an optimal cluster is formulated as a Markov Decision Process (MDP) in the algorithm and the obtained simulation results show convergence, learning and adaptability of the algorithm to dynamic environment towards achieving an optimal solution. Performance comparisons of our algorithm with the Groupwise Spectrum Aware (GWSA)-based algorithm in terms of Sum of Square Error (SSE), complexity, network energy consumption and probability of detection indicate improved performance from the proposed approach. The results further reveal that an energy savings of 9% and a significant Primary User (PU) detection improvement can be achieved with the proposed approach.

  10. Recent results from Yakutsk experiment: development of EAS, energy spectrum and primary particle mass composition in the energy region of 10^15-10^19 eV

    CERN Document Server

    Knurenko, S P; Pravdin, M I; Sabourov, A V; Sleptsov, I Ye

    2006-01-01

    Experimental data obtained at the Yakutsk array after the modernization in 1993 are analyzed. The characteristics of EAS longitudinal and radial development found from the charged particle flux and EAS Cherenkov light registered at the Yakutsk complex array are presented. The energy spectrum of EAS obtained from Cherenkov light and an estimate of the PCR mass composition are presented.

  11. Universal breaking point asymptotic for energy spectrum of Riemann waves in weakly nonlinear non-dispersive media

    CERN Document Server

    Kartashova, Elena

    2013-01-01

    In this Letter we study the form of the energy spectrum of Riemann waves in weakly nonlinear non-dispersive media. For quadratic and cubic nonlinearity we demonstrate that the deformation of an Riemann wave over time yields an exponential energy spectrum which turns into power law asymptotic with the slope being approximately -8/3 at the last stage of evolution before breaking. We argue, that this is the universal asymptotic behaviour of Riemann waves in any nonlinear non-dispersive medium at the point of breaking. The results reported in this Letter can be used in various non-dispersive media, e.g. magneto-hydro dynamics, physical oceanography, nonlinear acoustics.

  12. Beam collimation and energy spectrum compression of laser-accelerated proton beams using solenoid field and RF cavity

    International Nuclear Information System (INIS)

    This paper presents a new method of laser produced proton beam collimation and spectrum compression using a combination of a solenoid field and a RF cavity. The solenoid collects laser-driven protons efficiently within an angle that is smaller than 12 degrees because it is mounted few millimeters from the target, and collimates protons with energies around 2.3 MeV. The collimated proton beam then passes through a RF cavity to allow compression of the spectrum. Particle-in-cell (PIC) simulations demonstrate the proton beam transport in the solenoid and RF electric fields. Excellent energy compression and collection efficiency of protons are presented. This method for proton beam optimization is suitable for high repetition-rate laser acceleration proton beams, which could be used as an injector for a conventional proton accelerator

  13. Beam collimation and energy spectrum compression of laser-accelerated proton beams using solenoid field and RF cavity

    Science.gov (United States)

    Teng, J.; Gu, Y. Q.; Zhu, B.; Hong, W.; Zhao, Z. Q.; Zhou, W. M.; Cao, L. F.

    2013-11-01

    This paper presents a new method of laser produced proton beam collimation and spectrum compression using a combination of a solenoid field and a RF cavity. The solenoid collects laser-driven protons efficiently within an angle that is smaller than 12 degrees because it is mounted few millimeters from the target, and collimates protons with energies around 2.3 MeV. The collimated proton beam then passes through a RF cavity to allow compression of the spectrum. Particle-in-cell (PIC) simulations demonstrate the proton beam transport in the solenoid and RF electric fields. Excellent energy compression and collection efficiency of protons are presented. This method for proton beam optimization is suitable for high repetition-rate laser acceleration proton beams, which could be used as an injector for a conventional proton accelerator.

  14. Influence of a Transverse Electric Field on the Alternating Currents Rectification Effect in Superstructures with Non-additive Energy Spectrum

    Directory of Open Access Journals (Sweden)

    V.I. Konchenkov

    2015-12-01

    Full Text Available It is investigated the effect of mutual rectification of alternating currents, induced by an electric field of two uniformly polarized electromagnetic waves with different frequencies in two-dimensional superlattice with non-additive energy spectrum under the influence of a constant transverse electric field. The possibility of control of constant component of electric current (amplification, change of sign, suppression by the transverse electric field is shown. The abilities of the practical use of the results are discussed.

  15. Experimental determination of the energy response of alanine pellets in the high dose rate 192Ir spectrum

    Science.gov (United States)

    Schaeken, B.; Cuypers, R.; Goossens, J.; Van den Weyngaert, D.; Verellen, D.

    2011-10-01

    An experimental determination of the energy correction factor for alanine/paraffin pellets in the 192Ir spectrum at varying distances from the source is presented. Alanine dosimeters were irradiated in water under full scatter conditions with a high dose rate (HDR) 192Ir source (Flexisource), using a dedicated holder. Up to six line sources (catheters) fit in a regular pattern at fixed radial distances from the holder axis, the alanine detector being placed at the centre of the holder. The HDR source was stepping every 0.5 cm within a trocar needle within ± 3.0 cm around the medial plane through the detector in order to achieve dose homogeneity within the detector volume. The energy correction factor of alanine/paraffin pellets in 192Ir relative to 60Co was experimentally determined as the inverse ratio of the dose to water measured in water around the 192Ir source to the dose to water calculated in water using the TG-43 formalism. The pellets were read out with a Bruker EMXmicro spectrometer (X-band). The amplitude of the central line in the alanine absorption spectrum from pellets irradiated within the 192Ir spectrum was directly compared with the amplitude from 60Co-irradiated pellets. The energy correction factors of Harwell pellets irradiated in the 192Ir spectrum are 1.029 ± 0.02, 1.027 ± 0.02 and 1.045 ± 0.02 at a mean weighted source-detector distance of 2.0, 2.9 and 5.3 cm, respectively. The experimentally obtained values for the energy response are 1.3% lower compared to the theoretical values for radial distances smaller than 3 cm.

  16. Rigorous description of an energy spectrum of the isopropanol molecule taking into account the internal rotation of methyl tops

    Science.gov (United States)

    Burenin, A. V.

    2016-06-01

    By using the group chain methods, a rigorous algebraic model is constructed to describe the energy spectrum of the isopropanol molecule (CH3)2CHOH with an allowance for the internal motion of hydroxil and two identical methyl tops. The model is rigorous in the sense that its correctness is limited only by the correctness of a symmetry chosen to describe internal dynamics of the molecule.

  17. A Theoretical Diagnosis on Light Speed Anisotropy from GRAAL Experiment

    CERN Document Server

    Lingli, Zhou

    2012-01-01

    The light speed anisotropy, i.e., the variation of the light speed with respect to direction in an "absolute" reference frame, is a profound issue in physics. The one-way experiment, performed at the GRAAL facility of the European Synchrotron Radiation Facility (ESRF) in Grenoble, reported results on the light speed anisotropy by Compton scattering of laser photons on high-energy electrons. We show in this paper that the azimuthal distribution of the GRAAL experiment data can be elegantly reproduced by a new theory of Lorentz invariance violation or space-time anisotropy, based on a general principle of physical independence of the mathematical background manifold.

  18. Review of the anisotropy working group at UHECR-2012

    Directory of Open Access Journals (Sweden)

    Ivanov A.

    2013-06-01

    Full Text Available The study of ultra-high energy cosmic rays (UHECRs has recently experienced a jump in statistics as well as improved instrumentation. This has allowed a better sensitivity in searching for anisotropies in the arrival directions of cosmic rays. In this written version of the presentation given by the inter-collaborative “Anisotropy Working Group” at the International Symposium on Future Directions in UHECR physics at CERN in February 2012, we report on the current status for anisotropy searches in the arrival directions of UHECRs.

  19. Study of the very high energy gamma-ray spectrum from the Galactic Center and future prospects

    CERN Document Server

    Belikov, Alexander V; Silk, Joseph

    2016-01-01

    Ground-based gamma ray observations of the Galactic Center region have revealed a high energy gamma ray source spatially coincident with the gravitational centroid of our Galaxy. The pointlike emission detected by H.E.S.S. exhibits an energy cut-off at about 10 TeV. We identify the parameters of the best fit of the exponential and the super-exponential cutoff models to the spectrum of the pointlike source and find that super-exponential one provides a similar quality of the fit to the spectrum of the pointlike source as the best-fit exponential cutoff model, while a dark matter interpretation does not provide as good a fit in the whole energy range of the signal. Based on the magnitude of the flux we derive constraints in the plane of the slope of the density profile $\\gamma$ and the critical radius, below which the density is assumed to be constant, $r_c$. Motivated by recent results on the spectrum and morphology from H.E.S.S. and by the possible observation of a super-exponential cutoff, we forecast the ob...

  20. Exchange bias for ferromagnetic/antiferromagnetic bilayers with the uniaxial anisotropy being misaligned with the exchange anisotropy

    Institute of Scientific and Technical Information of China (English)

    BAI YuHao; YUN GuoHong

    2009-01-01

    Using the principle of minimal energy and S-W model, the exchange bias for ferromagnetic/antiferromagnetic bilayers has been investigated when the uniaxial anisotropy is misaligned with the exchange anisotropy. According to the relation between the energy of the bilayer and the orientation of ferromagnetic magnetization, it is found that the bilayer will be in the monostable state or bistable state when the external field is absent in the initial magnetization state. The monostable state or bistable state of the bilayer, which determines the angular dependence of exchange bias directly, is controlled by the competition between the exchange anisotropy and uniaxial anisotropy. When the applied field is parallel to the intrinsic easy axes and intrinsic hard axes, one of the switching fields of the hysteresis loop shows an abrupt change, while the other keep continuous by analyzing the magnetization reversal processes. Consequently, the exchange bias field and the coercivity will show a jump phenomenon.The numerical calculations indicate that both the magnitude and direction of the exchange anisotropy will significantly affect the angular dependence of exchange bias. The jump phenomenon of exchange bias is an intrinsic property of the bilayer, which is dependent on the interracial exchange-coupling constant, the orientation of the exchange anisotropy, the thickness and uniaxial anisotropy constant of the ferromagnetic layer.

  1. Exchange bias for ferromagnetic/antiferromagnetic bilayers with the uniaxial anisotropy being misaligned with the exchange anisotropy

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    Using the principle of minimal energy and S-W model,the exchange bias for ferromagnetic/antiferro-magnetic bilayers has been investigated when the uniaxial anisotropy is misaligned with the exchange anisotropy. According to the relation between the energy of the bilayer and the orientation of ferro-magnetic magnetization,it is found that the bilayer will be in the monostable state or bistable state when the external field is absent in the initial magnetization state. The monostable state or bistable state of the bilayer,which determines the angular dependence of exchange bias directly,is controlled by the competition between the exchange anisotropy and uniaxial anisotropy. When the applied field is parallel to the intrinsic easy axes and intrinsic hard axes,one of the switching fields of the hysteresis loop shows an abrupt change,while the other keep continuous by analyzing the magnetization reversal processes. Consequently,the exchange bias field and the coercivity will show a jump phenomenon. The numerical calculations indicate that both the magnitude and direction of the exchange anisotropy will significantly affect the angular dependence of exchange bias. The jump phenomenon of exchange bias is an intrinsic property of the bilayer,which is dependent on the interfacial exchange-coupling constant,the orientation of the exchange anisotropy,the thickness and uniaxial anisotropy constant of the ferromagnetic layer.

  2. Small-angle anisotropies in the CMBR from active sources

    CERN Document Server

    Battye, R A

    1997-01-01

    We consider the effects of photon diffusion on the small-angle microwave background anisotropies due to active source models. We find that fluctuations created just before the time of last scattering allow anisotropy to be created on scales much smaller than allowed by standard Silk damping. Using simple models for string and texture structure functions as examples, we illustrate the differences in the angular power spectrum at scales of order a few arcminutes. In particular, we find that the Doppler peak heights are modified by 10-50% and the small-angle fall-off is power law rather than exponential.

  3. Relativistic Density Functional Treatment of Magnetic Anisotropy

    OpenAIRE

    Zhang, Hongbin

    2009-01-01

    Spin-orbit coupling (SOC) reduces the spatial symmetry of ferromagnetic solids. That is, the physical properties of ferromagnetic materials are anisotropic, depending on the magnetization direction. In this thesis, by means of numerical calculations with full-relativistic density functional theory, we studied two kinds of physical properties: surface magnetic anisotropy energy (MAE) and anisotropic thermoelectric power due to Lifshitz transitions. After a short introduction to ...

  4. Absolute determination of inelastic mean-free paths and surface excitation parameters by absolute reflection electron energy loss spectrum analysis

    Science.gov (United States)

    Nagatomi, T.; Goto, K.

    2005-11-01

    An analytical approach was proposed for simultaneously determining an inelastic mean-free path (IMFP) and a surface excitation parameter (SEP) with absolute units by the analysis of an absolute experimental reflection electron energy loss spectrum. The IMFPs and SEPs in Ni were deduced for electrons of 300 to 3000 eV. The obtained IMFPs were in good agreement with those calculated using the TPP-2M equation. The Chen-type empirical formula was proposed for determining the SEP. The results confirmed the applicability of the present approach for determining the IMFP and SEP for medium-energy electrons.

  5. Rational electrostatic design of easy-axis magnetic anisotropy in a Zn(II) -Dy(III) -Zn(II) single-molecule magnet with a high energy barrier.

    Science.gov (United States)

    Oyarzabal, Itziar; Ruiz, José; Seco, José Manuel; Evangelisti, Marco; Camón, Agustín; Ruiz, Eliseo; Aravena, Daniel; Colacio, Enrique

    2014-10-27

    Two novel trinuclear complexes [ZnCl(μ-L)Ln(μ-L)ClZn][ZnCl3 (CH3 OH)]⋅3 CH3 OH (Ln(III) =Dy (1) and Er (2)) have been prepared from the compartmental ligand N,N'-dimethyl-N,N'-bis(2-hydroxy-3-formyl-5-bromo-benzyl)ethylenediamine (H2 L). X-ray studies reveal that Ln(III) ions are coordinated by two [ZnCl(L)](-) units through the phenoxo and aldehyde groups, giving rise to a LnO8 coordination sphere with square-antiprism geometry and strong easy-axis anisotropy of the ground state. Ab initio CASSCF+RASSI calculations carried out on 1 confirm that the ground state is an almost pure MJ =±15/2 Kramers doublet with a marked axial anisotropy, the magnetic moment is roughly collinear with the shortest DyO distances. This orientation of the local magnetic moment of the Dy(III) ion in 1 is adopted to reduce the electronic repulsion between the oblate electron shape of the MJ =±15/2 Kramers doublet and the phenoxo-oxygen donor atoms involved in the shortest DyO bonds. CASSCF+RASSI calculations also show that the ground and first excited states of the Dy(III) ion are separated by 129 cm(-1) . As expected for this large energy gap, compound 1 exhibits, in a zero direct-current field, thermally activated slow relaxation of the magnetization with a large Ueff =140 K. The isostructural Zn-Er-Zn species does not present significant SMM behavior as expected for the prolate electron-density distribution of the Er(III) ion leading to an easy-plane anisotropy of the ground doublet state. PMID:25251453

  6. The WiggleZ Dark Energy Survey: the selection function and z=0.6 galaxy power spectrum

    CERN Document Server

    Blake, Chris; Colless, Matthew; Couch, Warrick; Croom, Scott; Davis, Tamara; Drinkwater, Michael J; Forster, Karl; Glazebrook, Karl; Jelliffe, Ben; Jurek, Russell J; Li, I-hui; Madore, Barry; Martin, Chris; Pimbblet, Kevin; Poole, Gregory B; Pracy, Michael; Sharp, Rob; Wisnioski, Emily; Woods, David; Wyder, Ted

    2010-01-01

    We report one of the most accurate measurements of the three-dimensional large-scale galaxy power spectrum achieved to date, using 56,159 redshifts of bright emission-line galaxies at effective redshift z=0.6 from the WiggleZ Dark Energy Survey at the Anglo-Australian Telescope. We describe in detail how we construct the survey selection function allowing for the varying target completeness and redshift completeness. We measure the total power with an accuracy of approximately 5% in wavenumber bands of dk=0.01 h/Mpc. A model power spectrum including non-linear corrections, combined with a linear galaxy bias factor and a simple model for redshift-space distortions, provides a good fit to our data for scales k < 0.4 h/Mpc. The large-scale shape of the power spectrum is consistent with the best-fitting matter and baryon densities determined by observations of the Cosmic Microwave Background radiation. By splitting the power spectrum measurement as a function of tangential and radial wavenumbers we delineate t...

  7. Proton therapy monitoring by Compton imaging: influence of the large energy spectrum of the prompt-γ radiation

    Science.gov (United States)

    Hilaire, Estelle; Sarrut, David; Peyrin, Françoise; Maxim, Voichiţa

    2016-04-01

    In proton therapy, the prompt-γ (PG) radiation produced by the interactions between protons and matter is related to the range of the beam in the patient. Tomographic Compton imaging is currently studied to establish a PG image and verify the treatment. However the quality of the reconstructed images depends on a number of factors such as the volume attenuation, the spatial and energy resolutions of the detectors, incomplete absorptions of high energy photons and noise from other particles reaching the camera. The impact of all these factors was not assessed in details. In this paper we investigate the influence of the PG energy spectrum on the reconstructed images. To this aim, we describe the process from the Monte Carlo simulation of the proton irradiation, through the Compton imaging of the PG distribution, up to the image reconstruction with a statistical MLEM method. We identify specific PG energy windows that are more relevant to detect discrepancies with the treatment plan. We find that for the simulated Compton device, the incomplete absorption of the photons with energy above about 2 MeV prevents the observation of the PG distributions at specific energies. It also leads to blurred images and smooths the distal slope of the 1D PG profiles obtained as projections on the central beam axis. We show that a selection of the events produced by γ photons having deposited almost all their energy in the camera allows to largely improve the images, a result that emphasizes the importance of the choice of the detector. However, this initial-energy-based selection is not accessible in practice. We then propose a method to estimate the range of the PG profile both for specific deposited-energy windows and for the full spectrum emission. The method relies on two parameters. We use a learning approach for their estimation and we show that it allows to detect few millimeter shifts of the PG profiles.

  8. THz frequency spectrum of protein-solvent interaction energy using a recurrence plot-based Wiener-Khinchin method.

    Science.gov (United States)

    Karain, Wael

    2016-10-01

    The dynamics of a protein and the water surrounding it are coupled via nonbonded energy interactions. This coupling can exhibit a complex, nonlinear, and nonstationary nature. The THz frequency spectrum for this interaction energy characterizes both the vibration spectrum of the water hydrogen bond network, and the frequency range of large amplitude modes of proteins. We use a Recurrence Plot based Wiener-Khinchin method RPWK to calculate this spectrum, and the results are compared to those determined using the classical auto-covariance-based Wiener-Khinchin method WK. The frequency spectra for the total nonbonded interaction energy extracted from molecular dynamics simulations between the β-Lactamase Inhibitory Protein BLIP, and water molecules within a 10 Å distance from the protein surface, are calculated at 150, 200, 250, and 310 K, respectively. Similar calculations are also performed for the nonbonded interaction energy between the residues 49ASP, 53TYR, and 142PHE in BLIP, with water molecules within 10 Å from each residue respectively at 150, 200, 250, and 310 K. A comparison of the results shows that RPWK performs better than WK, and is able to detect some frequency data points that WK fails to detect. This points to the importance of using methods capable of taking the complex nature of the protein-solvent energy landscape into consideration, and not to rely on standard linear methods. In general, RPWK can be a valuable addition to the analysis tools for protein molecular dynamics simulations. Proteins 2016; 84:1549-1557. © 2016 Wiley Periodicals, Inc.

  9. Anisotropy of weakly vibrated granular flows.

    Science.gov (United States)

    Wortel, Geert H; van Hecke, Martin

    2015-10-01

    We experimentally probe the anisotropy of weakly vibrated flowing granular media. Depending on the driving parameters-flow rate and vibration strength-this anisotropy varies significantly. We show how the anisotropy collapses when plotted as a function of the driving stresses, uncovering a direct link between stresses and anisotropy. Moreover, our data suggest that for small anisotropies, the shear stresses vanish. Anisotropy of the fabric of granular media thus plays a crucial role in determining the rheology of granular flows. PMID:26565148

  10. Anisotropy of Weakly Vibrated Granular Flows

    OpenAIRE

    Wortel, Geert; Van Hecke, Martin

    2014-01-01

    We experimentally probe the anisotropy of the fabric of weakly vibrated, flowing granular media. Depending on the driving parameters --- flow rate and vibration strength --- this anisotropy varies significantly. We show how the anisotropy collapses when plotted as function of the driving stresses, uncovering a direct link between stresses and anisotropy. Moreover, our data suggests that for small anisotropies, the shear stresses vanish. Anisotropy of the fabric of granular media thus plays a ...

  11. INDICATIONS OF INTERMEDIATE-SCALE ANISOTROPY OF COSMIC RAYS WITH ENERGY GREATER THAN 57 EeV IN THE NORTHERN SKY MEASURED WITH THE SURFACE DETECTOR OF THE TELESCOPE ARRAY EXPERIMENT

    Energy Technology Data Exchange (ETDEWEB)

    Abbasi, R. U.; Abu-Zayyad, T.; Allen, M.; Anderson, R.; Barcikowski, E.; Belz, J. W.; Bergman, D. R.; Blake, S. A.; Cady, R.; Hanlon, W. [High Energy Astrophysics Institute and Department of Physics and Astronomy, University of Utah, Salt Lake City, UT (United States); Abe, M. [The Graduate School of Science and Engineering, Saitama University, Saitama, Saitama (Japan); Azuma, R. [Graduate School of Science and Engineering, Tokyo Institute of Technology, Meguro, Tokyo (Japan); Chae, M. J. [Department of Physics and Institute for the Early Universe, Ewha Womans University, Seodaaemun-gu, Seoul (Korea, Republic of); Cheon, B. G. [Department of Physics and The Research Institute of Natural Science, Hanyang University, Seongdong-gu, Seoul (Korea, Republic of); Chiba, J. [Department of Physics, Tokyo University of Science, Noda, Chiba (Japan); Chikawa, M. [Department of Physics, Kinki University, Higashi Osaka, Osaka (Japan); Cho, W. R. [Department of Physics, Yonsei University, Seodaemun-gu, Seoul (Korea, Republic of); Fujii, T.; Fukushima, M. [Institute for Cosmic Ray Research, University of Tokyo, Kashiwa, Chiba (Japan); Goto, T. [Graduate School of Science, Osaka City University, Osaka, Osaka (Japan); and others

    2014-08-01

    We have searched for intermediate-scale anisotropy in the arrival directions of ultrahigh-energy cosmic rays with energies above 57 EeV in the northern sky using data collected over a 5 yr period by the surface detector of the Telescope Array experiment. We report on a cluster of events that we call the hotspot, found by oversampling using 20° radius circles. The hotspot has a Li-Ma statistical significance of 5.1σ, and is centered at R.A. = 146.°7, decl. = 43.°2. The position of the hotspot is about 19° off of the supergalactic plane. The probability of a cluster of events of 5.1σ significance, appearing by chance in an isotropic cosmic-ray sky, is estimated to be 3.7 × 10{sup –4} (3.4σ)

  12. Indications of Intermediate-Scale Anisotropy of Cosmic Rays with Energy Greater Than 57 EeV in the Northern Sky Measured with the Surface Detector of the Telescope Array Experiment

    CERN Document Server

    Abbasi, R U; Abu-Zayyad, T; Allen, M; Anderson, R; Azuma, R; Barcikowski, E; Belz, J W; Bergman, D R; Blake, S A; Cady, R; Chae, M J; Cheon, B G; Chiba, J; Chikawa, M; Cho, W R; Fujii, T; Fukushima, M; Goto, T; Hanlon, W; Hayashi, Y; Hayashida, N; Hibino, K; Honda, K; Ikeda, D; Inoue, N; Ishii, T; Ishimori, R; Ito, H; Ivanov, D; Jui, C C H; Kadota, K; Kakimoto, F; Kalashev, O; Kasahara, K; Kawai, H; Kawakami, S; Kawana, S; Kawata, K; Kido, E; Kim, H B; Kim, J H; Kitamura, S; Kitamura, Y; Kuzmin, V; Kwon, Y J; Lan, J; Lim, S I; Lundquist, J P; Machida, K; Martens, K; Matsuda, T; Matsuyama, T; Matthews, J N; Minamino, M; Mukai, K; Myers, I; Nagasawa, K; Nagataki, S; Nakamura, T; Nonaka, T; Nozato, A; Ogio, S; Ogura, J; Ohnishi, M; Ohoka, H; Oki, K; Okuda, T; Ono, M; Oshima, A; Ozawa, S; Park, I H; Pshirkov, M S; Rodriguez, D C; Rubtsov, G; Ryu, D; Sagawa, H; Sakurai, N; Sampson, A L; Scott, L M; Shah, P D; Shibata, F; Shibata, T; Shimodaira, H; Shin, B K; Smith, J D; Sokolsky, P; Springer, R W; Stokes, B T; Stratton, S R; Stroman, T A; Suzawa, T; Takamura, M; Takeda, M; Takeishi, R; Taketa, A; Takita, M; Tameda, Y; Tanaka, H; Tanaka, K; Tanaka, M; Thomas, S B; Thomson, G B; Tinyakov, P; Tkachev, I; Tokuno, H; Tomida, T; Troitsky, S; Tsunesada, Y; Tsutsumi, K; Uchihori, Y; Udo, S; Urban, F; Vasiloff, G; Wong, T; Yamane, R; Yamaoka, H; Yamazaki, K; Yang, J; Yashiro, K; Yoneda, Y; Yoshida, S; Yoshii, H; Zollinger, R; Zundel, Z

    2014-01-01

    We have searched for intermediate-scale anisotropy in the arrival directions of ultrahigh-energy cosmic rays with energies above 57~EeV in the northern sky using data collected over a 5 year period by the surface detector of the Telescope Array experiment. We report on a cluster of events that we call the hotspot, found by oversampling using 20$\\degr$-radius circles. The hotspot has a statistical significance of 5.1$\\sigma$, and is centered at ${\\rm R.A.}=146\\fdg7$, ${\\rm Dec.}=43\\fdg2$. The position of the hotspot is about 19$\\degr$ off of the supergalactic plane. The probability of a cluster of events of 5.1$\\sigma$ significance, found using 20$\\degr$ radius oversampling, appearing by chance in an isotropic cosmic-ray sky is calculated to be 1.4$\\times$10$^{-4}$ (3.6$\\sigma$).

  13. Effect of muon-nuclear inelastic scattering on high-energy atmospheric muon spectrum at large depth underwater

    CERN Document Server

    Sinegovsky, S I; Lokhtin, K S; Takahashi, N

    2007-01-01

    The energy spectra of hadron cascade showers produced by the cosmic ray muons travelling through water as well as the muon energy spectra underwater at the depth up to 4 km are calculated with two models of muon inelastic scattering on nuclei, the recent hybrid model (two-component, 2C) and the well-known generalized ector-meson-dominance model for the comparison. The 2C model involves photonuclear interactions at low and moderate virtualities as well as the hard scattering including the weak neutral current processes. For the muon scattering off nuclei substantial uclear effects, shadowing, nuclear binding and Fermi motion of nucleons are taken into account. It is shown that deep nderwater muon energy spectrum calculated with the 2C model are noticeably distorted at energies above 100 TeV as compared to that obtained with the GVMD model.

  14. Anisotropy Graded Media: Extending the Superparamagnetic Limit (abstract)

    Science.gov (United States)

    Horton, K. Renee; Kang, S.; Harrell, J. W.

    2009-04-01

    The maximum storage density in magnetic media is limited by the superparamagnetic size of the grains that make up the bits. The superparamagnetic size can be reduced by increasing the anisotropy of the grains; however, in conventional media, in which the anisotropy of the grains is uniform, this leads to a proportionate increase in the switching field. The switching field, however, is limited by the maximum magnetization of the core material in the write head. Recent calculations have shown that the switching field can be significantly reduced relative to the thermal stability of the grains if the anisotropy is made to vary appropriately from the bottom to the top of the grain. In this project we propose to test this concept by fabricating and characterizing anisotropy graded films. We will use the hcp CoPtX system, with X = Cr or Ru, where the anisotropy gradient is obtained by grading the composition. Both sheet films and granular films will be fabricated. The anisotropy gradients will be determined by analyzing magnetization curves. Dynamic coercivity measurements will be used to determine the short-time coercivity and the zero-field energy barrier in the granular films. These results will be compared with similar measurements on films with uniform anisotropy films in order to test the predictions for graded media.

  15. Modelling the Multi-band Afterglow of GRB 091127: Evidence of a Hard Electron Energy Spectrum with an Injection Break

    CERN Document Server

    Zhang, Qiang; Zong, Hong-Shi

    2016-01-01

    The afterglow of GRBs is believed to originate from the synchrotron emission of shock-accelerated electrons produced by the interaction between the outflow and the external medium. The accelerated electrons are usually assumed to follow a power law energy distribution with an index of $p$. Observationally, although most GRB afterglows have a $p$ larger than 2, there are still a few GRBs suggestive of a hard ($p<2$) electron spectrum. GRB 091127, with well-sampled broad-band afterglow data, shows evidence of a hard electron spectrum and strong spectral evolution, with a spectral break moving from high to lower energies. The spectral break evolves very fast and cannot be explained by the cooling break in the standard afterglow model, unless evolving microphysical parameters are assumed. Besides, the multi-band afterglow light curves show an achromatic break at around 33 ks. Based on the model of a hard electron spectrum with an injection break, we interpret the observed spectral break as the synchrotron freq...

  16. Implementation of spectrum analysis in mesoscale modeling for wind energy assessment studies

    DEFF Research Database (Denmark)

    Stathopoulos, C.; Barranger, N.; Larsén, Xiaoli Guo;

    2012-01-01

    Spectral analysis of wind speed is a key parameter for the characterization of the physical processes generating the fields. Especially, the mesoscale power spectrum is an important measure of accuracy of wind forecasting and extreme wind estimation for modern wind farms, which are of the size of...

  17. Anelastic deformation processes in metallic glasses and activation energy spectrum model

    NARCIS (Netherlands)

    Ocelik, [No Value; Csach, K; Kasardova, A; Bengus, VZ; Ocelik, Vaclav

    1997-01-01

    The isothermal kinetics of anelastic deformation below the glass transition temperature (so-called 'stress induced ordering' or 'creep recovery' deformation) was investigated in Ni-Si-B metallic glass. The relaxation time spectrum model and two recently developed methods for its calculation from the

  18. On the nature of the pseudogap in the low-energy spectrum of noncubic Kondo insulators

    Energy Technology Data Exchange (ETDEWEB)

    Kagan, Y. (Kurchatov Institute, Kurchatov Sq., 123182 Moscow (Russian Federation)); Kikoin, K.A. (Kurchatov Institute, Kurchatov Sq., 123182 Moscow (Russian Federation)); Prokof' ev, N.V. (University of British Columbia, 6224 Agricultural Rd., Vancouver B.C., V6T 1Z1 (Canada))

    1994-04-01

    It is shown that the soft crystal electric field excitations in noncubic crystals interact strongly with the heavy fermions provided [Delta][sub CEF][<=]T[sub K]. This interaction results in forming the gap in the fermion spectrum which can be suppressed by an external magnetic field applied along the easy magnetization axis. ((orig.))

  19. Optimal Random Access and Random Spectrum Sensing for an Energy Harvesting Cognitive Radio with and without Primary Feedback Leveraging

    Directory of Open Access Journals (Sweden)

    Ahmed El Shafie

    2014-07-01

    Full Text Available We consider a secondary user (SU with energy harvesting capability. We design access schemes for the SU which incorporate random spectrum sensing and random access, and which make use of the primary automatic repeat request (ARQ feedback. We study two problem-formulations. In the first problemformulation, we characterize the stability region of the proposed schemes. The sensing and access probabilities are obtained such that the secondary throughput is maximized under the constraints that both the primary and secondary queues are stable. Whereas in the second problem-formulation, the sensing and access probabilities are obtained such that the secondary throughput is maximized under the stability of the primary queue and that the primary queueing delay is kept lower than a specified value needed to guarantee a certain quality of service (QoS for the primary user (PU. We consider spectrum sensing errors and assume multipacket reception (MPR capabilities. Numerical results show the enhanced performance of our proposed systems.

  20. Measurement of the B --> X_s gamma Branching Fraction and Photon Energy Spectrum using the Recoil Method

    CERN Document Server

    Aubert, B; Karyotakis, Yu; Lees, J P; Poireau, V; Prudent, X; Tisserand, V; Zghiche, A; Garra Tico, J; Graugès-Pous, E; López, L; Palano, A; Pappagallo, M; Eigen, G; Stugu, B; Sun, L; Abrams, G S; Battaglia, M; Brown, D N; Button-Shafer, J; Cahn, R N; Jacobsen, R G; Kadyk, J A; Kerth, L T; Kolomensky, Yu G; Kukartsev, G; Lopes-Pegna, D; Lynch, G; Orimoto, T J; Osipenkov, I L; Ronan, M T; Tackmann, K; Tanabé, T; Wenzel, W A; Del Amo-Sánchez, P; Hawkes, C M; Soni, N; Watson, A T; Koch, H; Schröder, T; Walker, D; Asgeirsson, D J; Çuhadar-Dönszelmann, T; Fulsom, B G; Hearty, C; Mattison, T S; McKenna, J A; Barrett, M; Khan, A; Saleem, M; Teodorescu, L; Blinov, V E; Bukin, A D; Buzykaev, A R; Druzhinin, V P; Golubev, V B; Onuchin, A P; Serednyakov, S I; Skovpen, Yu I; Solodov, E P; Todyshev, K Yu; Bondioli, M; Curry, S; Eschrich, I; Kirkby, D; Lankford, A J; Lund, P; Mandelkern, M; Martin, E C; Stoker, D P; Abachi, S; Buchanan, C; Gary, J W; Liu, F; Long, O; Shen, B C; Vitug, G M; Zhang, L; Paar, H P; Rahatlou, S; Sharma, V; Berryhill, J W; Campagnari, C; Cunha, A; Dahmes, B; Hong, T M; Kovalskyi, D; Richman, J D; Beck, T W; Eisner, A M; Flacco, C J; Heusch, C A; Kroseberg, J; Lockman, W S; Schalk, T; Schumm, B A; Seiden, A; Wilson, M G; Winstrom, L O; Chen, E; Cheng, C H; Echenard, B; Fang, F; Hitlin, D G; Narsky, I; Piatenko, T; Porter, F C; Andreassen, R; Mancinelli, G; Meadows, B T; Mishra, K; Sokoloff, M D; Blanc, F; Bloom, P C; Ford, W T; Hirschauer, J F; Kreisel, A; Nagel, M; Nauenberg, U; Olivas, A; Smith, J G; Ulmer, K A; Wagner, S R; Zhang, J; Ayad, R; Gabareen, A M; Soffer, A; Toki, W H; Wilson, R J; Altenburg, D D; Feltresi, E; Hauke, A; Jasper, H; Merkel, J; Petzold, A; Spaan, B; Wacker, K; Klose, V; Kobel, M J; Lacker, H M; Mader, W F; Nogowski, R; Schubert, J; Schubert, K R; Schwierz, R; Sundermann, J E; Volk, A; Bernard, D; Bonneaud, G R; Latour, E; Lombardo, V; Thiebaux, C; Verderi, M; Clark, P J; Gradl, W; Muheim, F; Playfer, S; Robertson, A I; Watson, J E; Xie, Y; Andreotti, M; Bettoni, D; Bozzi, C; Calabrese, R; Cecchi, A; Cibinetto, G; Franchini, P; Luppi, E; Negrini, M; Petrella, A; Piemontese, L; Prencipe, E; Santoro, V; Anulli, F; Baldini-Ferroli, R; Calcaterra, A; De Sangro, R; Finocchiaro, G; Pacetti, S; Patteri, P; Peruzzi, I M; Piccolo, M; Rama, M; Zallo, A; Buzzo, A; Contri, R; Lo Vetere, M; Macri, M M; Monge, M R; Passaggio, S; Patrignani, C; Robutti, E; Santroni, A; Tosi, S; Chaisanguanthum, K S; Morii, M; Wu, J; Dubitzky, R S; Marks, J; Schenk, S; Uwer, U; Bard, D J; Dauncey, P D; Nash, J A; Panduro-Vazquez, W; Tibbetts, M; Behera, P K; Chai, X; Charles, M J; Mallik, U; Cochran, J; Crawley, H B; Dong, L; Eyges, V; Meyer, W T; Prell, S; Rosenberg, E I; Rubin, A E; Gao, Y Y; Gritsan, A V; Guo, Z J; Lae, C K; Denig, A G; Fritsch, M; Schott, G; Arnaud, N; Bquilleux, J; D'Orazio, A; Davier, M; Grosdidier, G; Höcker, A; Lepeltier, V; Le Diberder, F; Lutz, A M; Pruvot, S; Roudeau, P; Schune, M H; Serrano, J; Sordini, V; Stocchi, A; Wang, W F; Wormser, G; Lange, D J; Wright, D M; Bingham, I; Burke, J P; Chavez, C A; Fry, J R; Gabathuler, E; Gamet, R; Hutchcroft, D E; Payne, D J; Schofield, K C; Touramanis, C; Bevan, A J; George, K A; Di Lodovico, F; Sacco, R; Cowan, G; Flächer, H U; Hopkins, D A; Paramesvaran, S; Salvatore, F; Wren, A C; Brown, D N; Davis, C L; Barlow, N R; Barlow, R J; Chia, Y M; Edgar, C L; Lafferty, G D; West, T J; Yi, J I; Anderson, J; Chen, C; Jawahery, A; Roberts, D A; Simi, G; Tuggle, J M; Dallapiccola, C; Hertzbach, S S; Li, X; Moore, T B; Salvati, E; Saremi, S; Cowan, R; Dujmic, D; Fisher, P H; Koeneke, K; Sciolla, G; Spitznagel, M; Taylor, F; Yamamoto, R K; Zhao, M; Mclachlin, S E; Patel, P M; Robertson, S H; Lazzaro, A; Palombo, F; Bauer, J M; Cremaldi, L; Eschenburg, V; Godang, R; Kroeger, R; Sanders, D A; Summers, D J; Zhao, H W; Brunet, S; Côté, D; Simard, M; Taras, P; Viaud, F B; Nicholson, H; De Nardo, Gallieno; Fabozzi, F; Lista, L; Monorchio, D; Sciacca, C; Baak, M A; Raven, G; Snoek, H L; Jessop, C P; Knoepfel, K J; LoSecco, J M; Benelli, G; Corwin, L A; Honscheid, K; Kagan, H; Kass, R; Morris, J P; Rahimi, A M; Regensburger, J J; Sekula, S J; Wong, Q K; Blount, N L; Brau, J E; Frey, R; Igonkina, O; Kolb, J A; Lu, M; Rahmat, R; Sinev, N B; Strom, D; Strube, J; Torrence, E; Gagliardi, N; Gaz, A; Margoni, M; Morandin, M; Pompili, A; Posocco, M; Rotondo, M; Simonetto, F; Stroili, R; Voci, C; Ben-Haim, E; Briand, H; Calderini, G; Chauveau, J; David, P; Del Buono, L; La Vaissière, C de; Hamon, O; Leruste, P; Malcles, J; Ocariz, J; Pérez, A; Prendki, J; Gladney, L; Biasini, M; Covarelli, R; Manoni, E; Angelini, C; Batignani, G; Bettarini, S; Carpinelli, M; Cenci, R; Cervelli, A; Forti, F; Giorgi, M A; Lusiani, A; Marchiori, G; Mazur, M A; Morganti, M; Neri, N; Paoloni, E; Rizzo, G; Walsh, J J; Biesiada, J; Lau, Y P; Lü, C

    2007-01-01

    We present a measurement of the branching fraction and photon energy spectrum for the decay B --> X_s gamma using data from the BaBar experiment. The data sample corresponds to an integrated luminosity of 210 fb^{-1}, from which approximately 680 000 BB events are tagged by a fully reconstructed hadronic decay of one of the B mesons. In the decay of the second B meson, an isolated high--energy photon is identified. We measure BR(B --> X_s gamma) = (3.66 +- 0.85_{stat} +- 0.60_{syst}) x 10^{-4} for photon energies E_gamma above 1.9 GeV in the B rest frame. From the measured spectrum we calculate the first and second moments for different minimum photon energies, which are used to extract the heavy-quark parameters m_b and mu_{pi}^2. In addition, measurements of the direct CP asymmetry and isospin asymmetry are presented.

  1. Evolution of the cosmic ray anisotropy above 10^{14} eV

    CERN Document Server

    Aglietta, M; Alessandro, B; Antonioli, P; Arneodo, F; Bergamasco, L; Bertaina, M; Bonino, R; Castellina, A; Chiavassa, A; Piazzoli, B D'Ettorre; Di Sciascio, G; Fulgione, W; Galeotti, P; Ghia, P L; Iacovacci, M; Mannocchi, G; Morello, C; Navarra, G; Saavedra, O; Stamerra, A; Trinchero, G C; Valchierotti, S; Vallania, P; Vernetto, S; Vigorito, C

    2009-01-01

    The amplitude and phase of the cosmic ray anisotropy are well established experimentally between 10^{11} eV and 10^{14} eV. The study of their evolution into the energy region 10^{14}-10^{16} eV can provide a significant tool for the understanding of the steepening ("knee") of the primary spectrum. In this letter we extend the EAS-TOP measurement performed at E_0 around 10^{14} eV, to higher energies by using the full data set (8 years of data taking). Results derived at about 10^{14} and 4x10^{14} eV are compared and discussed. Hints of increasing amplitude and change of phase above 10^{14} eV are reported. The significance of the observation for the understanding of cosmic ray propagation is discussed.

  2. The Cosmic Ray p+He energy spectrum in the 3-3000 TeV energy range measured by ARGO-YBJ

    Science.gov (United States)

    Mari, S. M.; Montini, P.

    2016-07-01

    The ARGO-YBJ experiment is a full coverage air shower detector operated at the Yangbajing International Cosmic Ray Observatory. The detector has been in stable data taking in its full configuration since November 2007 to February 2013. The high altitude and the high segmentation and spacetime resolution offer the possibility to explore the cosmic ray energy spectrum in a very wide range, from a few TeV up to the PeV region. The high segmentation allows a detailed measurement of the lateral distribution, which can be used in order to discriminate showers produced by light and heavy elements. In this work we present the measurement of the cosmic ray light component spectrum in the energy range 3-3000 TeV. The analysis has been carried out by using a two-dimensional unfolding method based on the Bayes' theorem.

  3. The inelastic neutron scattering spectrum of chromous acid at high energy transfers

    Science.gov (United States)

    Tomkinson, J.; Taylor, A. D.; Howard, J.; Eckert, J.; Goldstone, J. A.

    1985-02-01

    The inelastic incoherent neutron scattering spectrum of chromous acid, at 77 K, is presented. It is dominated by the intense bending mode at 1254 cm-1 with some modes at lower frequencies showing indications of dispersion. The antisymmetric stretch νas(OHS) {‖1>-‖2>} was assigned to a broad band centered at ˜2050 cm-1, significantly displaced for the IR assignment (1650 cm-1). The breadth of the band is due to the dispersion, and kinematic coupling, that is anticipated for this compound. These new data allows us to fit chromous acid more clearly into the general trend of hydrogen bonded compounds. Chromous acid compares very well in its overall INS spectrum with the isomorphous sodium bifluoride, except that the kinematic coupling between νas(OHO) and the symmetric stretch does not occur in this compound.

  4. Effects of electron temperature anisotropy on proton mirror instability evolution

    Science.gov (United States)

    Ahmadi, Narges; Germaschewski, Kai; Raeder, Joachim

    2016-06-01

    Proton mirror modes are large amplitude nonpropagating structures frequently observed in the magnetosheath. It has been suggested that electron temperature anisotropy can enhance the proton mirror instability growth rate while leaving the proton cyclotron instability largely unaffected, therefore causing the proton mirror instability to dominate the proton cyclotron instability in Earth's magnetosheath. Here we use particle-in-cell simulations to investigate the electron temperature anisotropy effects on proton mirror instability evolution. Contrary to the hypothesis, electron temperature anisotropy leads to excitement of the electron whistler instability. Our results show that the electron whistler instability grows much faster than the proton mirror instability and quickly consumes the electron-free energy so that there is no electron temperature anisotropy left to significantly impact the evolution of the proton mirror instability.

  5. Effects of electron temperature anisotropy on proton mirror instability evolution

    CERN Document Server

    Ahmadi, Narges; Raeder, Joachim

    2016-01-01

    Proton mirror modes are large amplitude nonpropagating structures frequently observed in the magnetosheath. It has been suggested that electron temperature anisotropy can enhance the proton mirror instability growth rate while leaving the proton cyclotron instability largely unaffected, therefore causing the proton mirror instability to dominate the proton cyclotron instability in Earth's magnetosheath. Here, we use particle-in-cell simulations to investigate the electron temperature anisotropy effects on proton mirror instability evolution. Contrary to the hypothesis, electron temperature anisotropy leads to excitement of the electron whistler instability. Our results show that the electron whistler instability grows much faster than the proton mirror instability and quickly consumes the electron free energy, so that there is no electron temperature anisotropy left to significantly impact the evolution of the proton mirror instability.

  6. Measurement of the energy spectrum of cosmic-ray induced neutrons aboard an ER-2 high-altitude airplane

    CERN Document Server

    Goldhagen, P E; Kniss, T; Reginatto, M; Singleterry, R C; Van Steveninck, W; Wilson, J W

    2002-01-01

    Crews working on present-day jet aircraft are a large occupationally exposed group with a relatively high average effective dose from galactic cosmic radiation. Crews of future high-speed commercial aircraft flying at higher altitudes would be even more exposed. To help reduce the significant uncertainties in calculations of such exposures, the atmospheric ionizing radiation (AIR) project, an international collaboration of 15 laboratories, made simultaneous radiation measurements with 14 instruments on five flights of a NASA ER-2 high-altitude aircraft. The primary AIR instrument was a highly sensitive extended-energy multisphere neutron spectrometer with lead and steel shells placed within the moderators of two of its 14 detectors to enhance response at high energies. Detector responses were calculated for neutrons and charged hadrons at energies up to 100 GeV using MCNPX. Neutron spectra were unfolded from the measured count rates using the new MAXED code. We have measured the cosmic-ray neutron spectrum (t...

  7. ADAPTIVE FULL-SPECTRUM SOLAR ENERGY SYSTEMS CROSS-CUTTING R&D ON ADAPTIVE FULL-SPECTRUM SOLAR ENERGY SYSTEMS FOR MORE EFFICIENT AND AFFORDABLE USE OF SOLAR ENERGY IN BUILDINGS AND HYBRID PHOTOBIOREACTORS

    Energy Technology Data Exchange (ETDEWEB)

    Byard D. Wood; Jeff D. Muhs

    2004-08-01

    This RD&D project is a three year team effort to develop a hybrid solar lighting (HSL) system that transports daylight from a paraboloidal dish concentrator to a luminaire via a bundle of small core or a large core polymer fiber optics. The luminaire can be a device to distribute sunlight into a space for the production of algae or it can be a device that is a combination of daylighting and electric lighting for space/task lighting. In this project, the sunlight is collected using a one-meter paraboloidal concentrator dish with two-axis tracking. For the second generation (alpha) system, the secondary mirror is an ellipsoidal mirror that directs the visible light into a bundle of small-core fibers. The IR spectrum is filtered out to minimize unnecessary heating at the fiber entrance region. This report describes the following investigations of various aspects of the system. Taken as a whole, they confirm significant progress towards the technical feasibility and commercial viability of this technology. (1) TRNSYS Modeling of a Hybrid Lighting System: Building Energy Loads and Chromaticity Analysis; (2) High Lumens Screening Test Setup for Optical Fibers; (3) Photo-Induced Heating in Plastic Optical Fiber Bundles; (4) Low-Cost Primary Mirror Development; (5) Potential Applications for Hybrid Solar Lighting; (6) Photobioreactor Population Experiments and Productivity Measurements; and (7) Development of a Microalgal CO2-Biofixation Photobioreactor.

  8. Study of the π+ meson energy spectrum below 30 MeV in the decay K+→π++π0+π0

    International Nuclear Information System (INIS)

    Results are presented of an emulsion study of the low energy part of the π+ spectrum (1 MeV + mesons at rest. Contrary to the findings of Davison et al. this experiment shows no evidence for the existence of the sigma(π0π0) resonant state, there being no lack of events at the lowest energies. The spectrum is analysed in terms of a standard polynomial development of the decay matrix element. (Auth.)

  9. Exact third-order density perturbation and one-loop power spectrum in general dark energy models

    Directory of Open Access Journals (Sweden)

    Seokcheon Lee

    2014-09-01

    Full Text Available Under the standard perturbation theory (SPT, we obtain the fully consistent third-order density fluctuation and kernels for the general dark energy models without using the Einstein–de Sitter (EdS universe assumption for the first time. We also show that even though the temporal and spatial components of the SPT solutions cannot be separable, one can find the exact solutions to any order in general dark energy models. With these exact solutions, we obtain the less than % error correction of one-loop matter power spectrum compared to that obtained from the EdS assumption for k=0.1 hMpc−1 mode at z=0(1,1.5. Thus, the EdS assumption works very well at this scale. However, if one considers the correction for P13, the error is about 6 (9, 11% for the same mode at z=0(1,1.5. One absorbs P13 into the linear power spectrum in the renormalized perturbation theory (RPT and thus one should use the exact solution instead of the approximation one. The error on the resummed propagator N of RPT is about 14 (8, 6% at z=0(1,1.5 for k=0.4 hMpc−1. For k=1 hMpc−1, the error correction of the total matter power spectrum is about 3.6 (4.6, 4.5% at z=0(1,1.5. Upcoming observation is required to archive the sub-percent accuracy to provide the strong constraint on the dark energy and this consistent solution is prerequisite for the model comparison.

  10. Measurement of the energy spectrum of cosmic-ray induced neutrons aboard an ER-2 high-altitude airplane.

    Science.gov (United States)

    Goldhagen, P; Reginatto, M; Kniss, T; Wilson, J W; Singleterry, R C; Jones, I W; Van Steveninck, W

    2002-01-01

    Crews working on present-day jet aircraft are a large occupationally exposed group with a relatively high average effective dose from galactic cosmic radiation. Crews of future high-speed commercial aircraft flying at higher altitudes would be even more exposed. To help reduce the significant uncertainties in calculations of such exposures, the atmospheric ionizing radiation (AIR) project, an international collaboration of 15 laboratories, made simultaneous radiation measurements with 14 instruments on five flights of a NASA ER-2 high-altitude aircraft. The primary AIR instrument was a highly sensitive extended-energy multisphere neutron spectrometer with lead and steel shells placed within the moderators of two of its 14 detectors to enhance response at high energies. Detector responses were calculated for neutrons and charged hadrons at energies up to 100 GeV using MCNPX. Neutron spectra were unfolded from the measured count rates using the new MAXED code. We have measured the cosmic-ray neutron spectrum (thermal to >10 GeV), total neutron fluence rate, and neutron effective dose and dose equivalent rates and their dependence on altitude and geomagnetic cutoff. The measured cosmic-ray neutron spectra have almost no thermal neutrons, a large "evaporation" peak near 1 MeV and a second broad peak near 100 MeV which contributes about 69% of the neutron effective dose. At high altitude, geomagnetic latitude has very little effect on the shape of the spectrum, but it is the dominant variable affecting neutron fluence rate, which was eight times higher at the northernmost measurement location than it was at the southernmost. The shape of the spectrum varied only slightly with altitude from 21 km down to 12 km (56-201 g cm-2 atmospheric depth), but was significantly different on the ground. In all cases, ambient dose equivalent was greater than effective dose for cosmic-ray neutrons.

  11. Measurements of the neutron dose and energy spectrum on the International Space Station during expeditions ISS-16 to ISS-21.

    Science.gov (United States)

    Smith, M B; Akatov, Yu; Andrews, H R; Arkhangelsky, V; Chernykh, I V; Ing, H; Khoshooniy, N; Lewis, B J; Machrafi, R; Nikolaev, I; Romanenko, R Y; Shurshakov, V; Thirsk, R B; Tomi, L

    2013-01-01

    As part of the international Matroshka-R and Radi-N experiments, bubble detectors have been used on board the ISS in order to characterise the neutron dose and the energy spectrum of neutrons. Experiments using bubble dosemeters inside a tissue-equivalent phantom were performed during the ISS-16, ISS-18 and ISS-19 expeditions. During the ISS-20 and ISS-21 missions, the bubble dosemeters were supplemented by a bubble-detector spectrometer, a set of six detectors that was used to determine the neutron energy spectrum at various locations inside the ISS. The temperature-compensated spectrometer set used is the first to be developed specifically for space applications and its development is described in this paper. Results of the dose measurements indicate that the dose received at two different depths inside the phantom is not significantly different, suggesting that bubble detectors worn by a person provide an accurate reading of the dose received inside the body. The energy spectra measured using the spectrometer are in good agreement with previous measurements and do not show a strong dependence on the precise location inside the station. To aid the understanding of the bubble-detector response to charged particles in the space environment, calculations have been performed using a Monte-Carlo code, together with data collected on the ISS. These calculations indicate that charged particles contribute space.

  12. Anisotropy in rotating drums

    Science.gov (United States)

    Povall, Timothy; McBride, Andrew; Govender, Indresan

    2015-11-01

    An anisotropic relationship between the stress and the strain rate has been observed in two-dimensional simulations of rotating drums. The objective of this work is to investigate the structure of the constitutive relation using three-dimensional discrete-element-method simulations of a rotating drum containing identical rigid spheres for a range of rotational speeds. Anisotropy is quantified from the alignment of the stress and strain rate tensors, with the strain rate computed using a least-squares fit. It is shown that in certain regions there is a strong anisotropic relationship, regardless of the speed of rotation. The effective friction coefficient is examined in order to determine the phase space in which the μ (I) rheology is valid. Lastly, a depth-averaged approach through the flowing layer is employed to determine the relationship between the velocity tangential to the equilibrium surface and the height of the flowing layer. A power-law relationship that approaches linear at high speeds is observed. Supported by NRF/DST Scarce Skills (South Africa).

  13. Anisotropy in solid inflation

    International Nuclear Information System (INIS)

    In the model of solid / elastic inflation, inflation is driven by a source that has the field theoretical description of a solid. To allow for prolonged slow roll inflation, the solid needs to be extremely insensitive to the spatial expansion. We point out that, because of this property, the solid is also rather inefficient in erasing anisotropic deformations of the geometry. This allows for a prolonged inflationary anisotropic solution, providing the first example with standard gravity and scalar fields only which evades the conditions of the so called cosmic no-hair conjecture. We compute the curvature perturbations on the anisotropic solution, and the corresponding phenomenological bound on the anisotropy. Finally, we discuss the analogy between this model and the f(φ)F2 model, which also allows for anisotropic inflation thanks to a suitable coupling between the inflaton φ and a vector field. We remark that the bispectrum of the curvature perturbations in solid inflation is enhanced in the squeezed limit and presents a nontrivial angular dependence, as had previously been found for the f(φ)F2 model

  14. Measurement of the energy spectrum of cosmic rays with the 26 station configuration of the IceTop detector

    Energy Technology Data Exchange (ETDEWEB)

    Kislat, Fabian

    2011-09-27

    IceTop is an instrument at the geographic South Pole designed to detect cosmic ray air showers, particle cascades in the atmosphere initiated by high-energy cosmic rays. It is the surface component of the IceCube neutrino telescope. Since its completion in December 2010, IceTop consists of 81 detector stations covering an area of one square kilometer on the ice surface above IceCube. Each IceTop station consists of two ice-filled tanks in which the Cherenkov light emitted by charged air shower particles is measured. In this dissertation, an analysis of data taken in 2007 with 26 IceTop stations operational at that time is presented. First, properties of air showers like core position, direction and shower size were reconstructed from the measured signals. The core position can be determined to an accuracy of up to 6m and a direction resolution of up to 0.3 is achieved. The shower size is a measure of the energy of the primary particle and a resolution of up to 10% is achieved at high energies. In the next step the relation between primary energy and shower size, as well as resolution and efficiency are determined from Monte Carlo simulations of air showers and the IceTop detector. Here, an assumption was made about the chemical composition of cosmic rays. The informations obtained in these simulations are then used to unfold the spectrum of measured shower sizes in order to obtain the all-particle cosmic ray energy spectrum. This is done independently for particles from three different zenith angle intervals. The result of the unfolding depends on the assumed primary composition. Due to the isotropy of cosmic rays, results obtained in different zenith angle intervals must agree. While with the chosen analysis technique a simultaneous determination of primary particle mass and energy is limited due to systematic uncertainties, it has already been shown that the requirement of isotropy can be used to constrain the range of possible assumptions on the chemical

  15. Wide-spectrum energy harvesting out of colored Lévy-like fluctuations, by monostable piezoelectric transducers

    Science.gov (United States)

    Deza, J. Ignacio; Deza, Roberto R.; Wio, Horacio S.

    2012-11-01

    This work aims to optimize the overall performance of a model oscillator, as an energy harvester of Lévy-like mesoscopic fluctuations through piezoelectric conversion. As a further step in the description of a realistic harvesting device we consider a monostable Woods-Saxon oscillator, which can interpolate between square well and harmonic-like behaviors. We study the interplay between the potential shape and the noise's spectrum and statistics. The dependence of the power output on the parameters determining those features indicates the directions in which the former can be increased.

  16. Search for Large Scale Anisotropies with the Pierre Auger Observatory

    Science.gov (United States)

    Bonino, R.; Pierre Auger Collaboration

    The Pierre Auger Observatory studies the nature and the origin of Ultra High Energy Cosmic Rays (>3\\cdot1018 eV). Completed at the end of 2008, it has been continuously operating for more than six years. Using data collected from 1 January 2004 until 31 March 2009, we search for large scale anisotropies with two complementary analyses in different energy windows. No significant anisotropies are observed, resulting in bounds on the first harmonic amplitude at the 1% level at EeV energies.

  17. Determination of the energy spectrum of the neutrons in the central thimble of the reactor core TRIGA Mark III

    International Nuclear Information System (INIS)

    This thesis presents the neutron spectrum measurements inside the core of the TRIGA Mark III reactor at 1 MW power in steady-state, with the bridge placed in the center of the swimming pool, using several metallic threshold foils. The activation detectors are inserted in the Central Thimble of the reactor core, all the foils are irradiated in the same position and irradiation conditions (one by one). The threshold detectors are made of different materials such as: Au197, Ni58, In115, Mg24, Al27, Fe58, Co59 and Cu63, they were selected to cover the full range the energies (10-10 to 20 MeV) of the neutron spectrum in the reactor core. After the irradiation, the activation detectors were measured by means of spectrometry gamma, using a high resolution counting system with a hyper pure Germanium crystal, in order to obtain the saturation activity per target nuclide. The saturation activity is one of the main input data together with the initial spectrum, for the computational code SANDBP (hungarian version of the code SAND-II), which through an iterative adjustment, gives the calculated spectrum. The different saturation activities are necessary for the unfolding method, used by the computational code SANDBP. This research work is very important, since the knowledge of the energetic and spatial distribution of the neutron flux in the irradiation facilities, allows to characterize properly the irradiation facilities, just like, to estimate with a good precision various physics parameters of the reactor such as: neutron fluxes (thermal, intermediate and fast), neutronic dose, neutron activation analysis (NAA), spectral indices (cadmium ratio), buckling, fuel burnup, safety parameters (reactivity, temperature distribution, peak factors). In addition, the knowledge of the already mentioned parameters can give a best use of reactor, optimizing the irradiations requested by the users for their production process or research projects. (Author)

  18. Broad energy range neutron spectroscopy using a liquid scintillator and a proportional counter: Application to a neutron spectrum similar to that from an improvised nuclear device

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Yanping, E-mail: yx2132@cumc.columbia.edu; Randers-Pehrson, Gerhard; Marino, Stephen A.; Garty, Guy; Harken, Andrew; Brenner, David J.

    2015-09-11

    A novel neutron irradiation facility at the Radiological Research Accelerator Facility (RARAF) has been developed to mimic the neutron radiation from an Improvised Nuclear Device (IND) at relevant distances (e.g. 1.5 km) from the epicenter. The neutron spectrum of this IND-like neutron irradiator was designed according to estimations of the Hiroshima neutron spectrum at 1.5 km. It is significantly different from a standard reactor fission spectrum, because the spectrum changes as the neutrons are transported through air, and it is dominated by neutron energies from 100 keV up to 9 MeV. To verify such wide energy range neutron spectrum, detailed here is the development of a combined spectroscopy system. Both a liquid scintillator detector and a gas proportional counter were used for the recoil spectra measurements, with the individual response functions estimated from a series of Monte Carlo simulations. These normalized individual response functions were formed into a single response matrix for the unfolding process. Several accelerator-based quasi-monoenergetic neutron source spectra were measured and unfolded to test this spectroscopy system. These reference neutrons were produced from two reactions: T(p,n){sup 3}He and D(d,n){sup 3}He, generating neutron energies in the range between 0.2 and 8 MeV. The unfolded quasi-monoenergetic neutron spectra indicated that the detection system can provide good neutron spectroscopy results in this energy range. A broad-energy neutron spectrum from the {sup 9}Be(d,n) reaction using a 5 MeV deuteron beam, measured at 60 degrees to the incident beam was measured and unfolded with the evaluated response matrix. The unfolded broad neutron spectrum is comparable with published time-of-flight results. Finally, the pair of detectors were used to measure the neutron spectrum generated at the RARAF IND-like neutron facility and a comparison is made to the neutron spectrum of Hiroshima.

  19. Broad energy range neutron spectroscopy using a liquid scintillator and a proportional counter: Application to a neutron spectrum similar to that from an improvised nuclear device

    Science.gov (United States)

    Xu, Yanping; Randers-Pehrson, Gerhard; Marino, Stephen A.; Garty, Guy; Harken, Andrew; Brenner, David J.

    2015-09-01

    A novel neutron irradiation facility at the Radiological Research Accelerator Facility (RARAF) has been developed to mimic the neutron radiation from an Improvised Nuclear Device (IND) at relevant distances (e.g. 1.5 km) from the epicenter. The neutron spectrum of this IND-like neutron irradiator was designed according to estimations of the Hiroshima neutron spectrum at 1.5 km. It is significantly different from a standard reactor fission spectrum, because the spectrum changes as the neutrons are transported through air, and it is dominated by neutron energies from 100 keV up to 9 MeV. To verify such wide energy range neutron spectrum, detailed here is the development of a combined spectroscopy system. Both a liquid scintillator detector and a gas proportional counter were used for the recoil spectra measurements, with the individual response functions estimated from a series of Monte Carlo simulations. These normalized individual response functions were formed into a single response matrix for the unfolding process. Several accelerator-based quasi-monoenergetic neutron source spectra were measured and unfolded to test this spectroscopy system. These reference neutrons were produced from two reactions: T(p,n)3He and D(d,n)3He, generating neutron energies in the range between 0.2 and 8 MeV. The unfolded quasi-monoenergetic neutron spectra indicated that the detection system can provide good neutron spectroscopy results in this energy range. A broad-energy neutron spectrum from the 9Be(d,n) reaction using a 5 MeV deuteron beam, measured at 60 degrees to the incident beam was measured and unfolded with the evaluated response matrix. The unfolded broad neutron spectrum is comparable with published time-of-flight results. Finally, the pair of detectors were used to measure the neutron spectrum generated at the RARAF IND-like neutron facility and a comparison is made to the neutron spectrum of Hiroshima.

  20. Evaluation of Kolmogorov - Smirnov Test and Energy Detector Techniques for Cooperative Spectrum Sensing in Real Channel Conditions

    OpenAIRE

    D. Lekomtcev; R. Marsalek

    2015-01-01

    The cognitive radio technology allows solving one of the main issues of current wireless communication technologies, namely a deficit of vacant spectrum. A dynamic spectrum access used in the cognitive radio networks (CRN) gives an ability to access an unused spectrum in real time. Cooperative spectrum sensing is the most effective method for spectrum holes detecting. It combines sensing information of multiple cognitive radio users. In this paper, an experimental evaluation of spectrum sensi...

  1. Non-elliptic wavevector anisotropy for magnetohydrodynamic turbulence

    Science.gov (United States)

    Narita, Y.

    2015-11-01

    A model of non-elliptic wavevector anisotropy is developed for the inertial-range spectrum of magnetohydrodynamic turbulence and is presented in the two-dimensional wavevector domain spanning the directions parallel and perpendicular to the mean magnetic field. The non-elliptic model is a variation of the elliptic model with different scalings along the parallel and the perpendicular components of the wavevectors to the mean magnetic field. The non-elliptic anisotropy model reproduces the smooth transition of the power-law spectra from an index of -2 in the parallel projection with respect to the mean magnetic field to an index of -5/3 in the perpendicular projection observed in solar wind turbulence, and is as competitive as the critical balance model to explain the measured frequency spectra in the solar wind. The parameters in the non-elliptic spectrum model are compared with the solar wind observations.

  2. Energy spectrum measurement and dose rate estimation of natural neutrons in Tibet region

    Institute of Scientific and Technical Information of China (English)

    吴建华; 徐勇军; 刘森林; 汪传高

    2015-01-01

    In this work, natural neutron spectra at nine sites in Tibet region were measured using a multi-sphere neutron spectrometer. The altitude-dependence of the spectra total fluence rate and ambient dose equivalent rate were analyzed. From the normalized natural neutron spectra at different altitudes, the spectrum fractions for neutrons of greater than 0.1 MeV do not differ obviously, while those of the thermal neutrons differ greatly from each other. The total fluence rate, effective dose rate and the ambient dose equivalent rate varied with the altitude according to an exponential law.

  3. Results from the Wilkinson Microwave Anisotropy Probe

    Science.gov (United States)

    Komatsu, E.; Bennett, Charles L.; Komatsu, Eiichiro

    2015-01-01

    The Wilkinson Microwave Anisotropy Probe (WMAP) mapped the distribution of temperature and polarization over the entire sky in five microwave frequency bands. These full-sky maps were used to obtain measurements of temperature and polarization anisotropy of the cosmic microwave background with the unprecedented accuracy and precision. The analysis of two-point correlation functions of temperature and polarization data gives determinations of the fundamental cosmological parameters such as the age and composition of the universe, as well as the key parameters describing the physics of inflation, which is further constrained by three-point correlation functions. WMAP observations alone reduced the flat ? cold dark matter (Lambda Cold Dark Matter) cosmological model (six) parameter volume by a factor of > 68, 000 compared with pre-WMAP measurements. The WMAP observations (sometimes in combination with other astrophysical probes) convincingly show the existence of non-baryonic dark matter, the cosmic neutrino background, flatness of spatial geometry of the universe, a deviation from a scale-invariant spectrum of initial scalar fluctuations, and that the current universe is undergoing an accelerated expansion. The WMAP observations provide the strongest ever support for inflation; namely, the structures we see in the universe originate from quantum fluctuations generated during inflation.

  4. Cosmic ray electron anisotropies as a tool to discriminate between exotic and astrophysical sources

    CERN Document Server

    Cernuda, Ignacio

    2009-01-01

    Recent results from the PAMELA, ATIC, PPB BETS and Fermi collaborations extend the energy range in the electron flux measurement up to unexplored energies in the hundred GeVs range confirming the bump starting at about 10GeV already suggested by HEAT and AMS01 data . This bump can be explained by annihilating dark matter in the context of exotic physics, or by nearby astrophysical sources e.g. pulsars. In order to discriminate between competing models for primary positron production, the study of anisotropies ,complementary to the spectrum determination, shows up as new tool to look for the origin of the lepton excess. In this letter we calculate the contribution to the electron flux given by the collection of all known gamma ray pulsars (as listed in the ATNF catalogue) and by annihilating dark matter both in case of a clumpy halo or in case the excess can be atributed to a nearby sizeable dark matter clump. We address the problem of the electron anisotropy in both scenarios and estimate the prospect that a ...

  5. Inverse Compton gamma-rays from galactic dark matter annihilation. Anisotropy signatures

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Le; Sigl, Guenter [Hamburg Univ. (Germany). 2. Inst. fuer Theoretische Physik; Miniati, Francesco [ETH Zuerich (Switzerland). Physics Dept.

    2010-08-15

    High energy electrons and positrons from annihilating dark matter can imprint unique angular anisotropies on the diffuse gamma-ray flux by inverse Compton scattering off the interstellar radiation field. We develop a numerical tool to compute gamma-ray emission from such electrons and positrons diffusing in the smooth host halo and in substructure halos with masses down to 10{sup -6}M{sub s}un. We show that, unlike the total gamma-ray angular power spectrum observed by Fermi-LAT, the angular power spectrum from inverse Compton scattering is exponentially suppressed below an angular scale determined by the diffusion length of electrons and positrons. For TeV scale dark matter with a canonical thermal freeze-out cross section 3 x 10{sup -26} cm{sup 3}/s, this feature may be detectable by Fermi-LAT in the energy range 100-300 GeV after more sophisticated foreground subtraction. We also find that the total flux and the shape of the angular power spectrum depends sensitively on the spatial distribution of subhalos in the Milky Way. Finally, the contribution from the smooth host halo component to the gamma-ray mean intensity is negligibly small compared to subhalos. (orig.)

  6. Inverse Compton gamma-rays from Galactic dark matter annihilation: Anisotropy signatures

    CERN Document Server

    Zhang, Le; Sigl, Guenter

    2010-01-01

    High energy electrons and positrons from annihilating dark matter can imprint unique angular anisotropies on the diffuse gamma-ray flux by inverse Compton scattering off the interstellar radiation field. We develop a numerical tool to compute gamma-ray emission from such electrons and positrons diffusing in the smooth host halo and in substructure halos with masses down to 10^(-6) M_sun. We show that, unlike the total gamma-ray angular power spectrum observed by Fermi-LAT, the angular power spectrum from inverse Compton scattering is exponentially suppressed below an angular scale determined by the diffusion length of electrons and positrons. For TeV scale dark matter with a canonical thermal freeze-out cross section 3 x 10^(-26) cm^3/s, this feature may be detectable by Fermi-LAT in the energy range 100-300 GeV after more sophisticated foreground subtraction. We also find that the total flux and the shape of the angular power spectrum depends sensitively on the spatial distribution of subhalos in the Milky W...

  7. A method to detect positron anisotropies with Pamela data

    Energy Technology Data Exchange (ETDEWEB)

    Panico, B. [INFN, Sezione di Naples, I-80126 Naples (Italy); Adriani, O. [University of Florence, Department of Physics and Astronomy, I-50019 Sesto Fiorentino, Florence (Italy); INFN, Sezione di Florence, I-50019 Sesto Fiorentino, Florence (Italy); Barbarino, G.C. [INFN, Sezione di Naples, I-80126 Naples (Italy); University of Naples Federico II”, Department of Physics, I-80126 Naples (Italy); Bazilevskaya, G.A. [Lebedev Physical Institute, RU-119991, Moscow (Russian Federation); Bellotti, R. [University of Bari, Department of Physics, I-70126 Bari (Italy); INFN, Sezione di Bari, I-70126 Bari (Italy); Boezio, M. [INFN, Sezione di Trieste, I-34149 Trieste (Italy); Bogomolov, E.A. [Ioffe Physical Technical Institute, RU-194021 St. Petersburg (Russian Federation); Bongi, M. [University of Florence, Department of Physics and Astronomy, I-50019 Sesto Fiorentino, Florence (Italy); INFN, Sezione di Florence, I-50019 Sesto Fiorentino, Florence (Italy); Bonvicini, V. [INFN, Sezione di Trieste, I-34149 Trieste (Italy); Bottai, S. [University of Naples Federico II”, Department of Physics, I-80126 Naples (Italy); Bruno, A. [University of Bari, Department of Physics, I-70126 Bari (Italy); INFN, Sezione di Bari, I-70126 Bari (Italy); Cafagna, F. [INFN, Sezione di Bari, I-70126 Bari (Italy); Campana, D. [INFN, Sezione di Naples, I-80126 Naples (Italy); Carbone, R. [INFN, Sezione di Trieste, I-34149 Trieste (Italy); Carlson, P. [KTH, Department of Physics, and the Oskar Klein Centre for Cosmoparticle Physics, AlbaNova University Centre, SE-10691 Stockholm (Sweden); Casolino, M. [INFN, Sezione di Rome Tor Vergata, I-00133 Rome (Italy); RIKEN, Advanced Science Institute, Wako-shi, Saitama (Japan); Castellini, G. [IFAC, I-50019 Sesto Fiorentino, Florence (Italy); De Donato, C. [INFN, Sezione di Rome Tor Vergata, I-00133 Rome (Italy); and others

    2014-11-15

    The PAMELA experiment is collecting data since 2006; its results indicate the presence of a large flux of positron with respect to electrons in the CR spectrum above 10 GeV. This excess might also be originated in objects such as pulsars and microquasars or through dark matter annihilation. Here the electrons and positrons events collected by PAMELA have been analized searching for anisotropies. The analysis is performed at different angular scales and results will be presented at the conference.

  8. Effects of velocity-dependent dark matter annihilation on the energy spectrum of the extragalactic gamma-ray background

    Science.gov (United States)

    Campbell, Sheldon; Dutta, Bhaskar; Komatsu, Eiichiro

    2010-11-01

    We calculate the effects of velocity-dependent dark matter annihilation cross sections on the intensity of the extragalactic gamma-ray background. Our formalism does not assume a locally thermal distribution of dark matter particles in phase space, and is valid for arbitrary velocity-dependent annihilation. Although the model of the dark matter distribution we use is simple and may not describe nature precisely, it is sufficient for quantifying the effects of velocity-dependent annihilations: different halo models would be expected to produce the same general features. As concrete examples, we calculate the effects of p-wave annihilation (with the v-weighted cross section of σv=a+bv2) on the mean intensity of extragalactic gamma rays produced in cosmological dark matter halos. This velocity variation makes the shape of the energy spectrum harder, but this change in the shape is too small to see unless b/a≳106. While we find no such models in the parameter space of the minimal supersymmetric standard model, we show that it is possible to find b/a≳106 in the extension MSSM⊗U(1)B-L. However, we find that the most dominant effect of the p-wave annihilation is the suppression of the amplitude of the gamma-ray background. A nonzero b at the dark matter freeze-out epoch requires a smaller value of a in order for the relic density constraint to be satisfied, suppressing the amplitude by a factor as low as 10-6 for a thermal relic. Nonthermal relics will have weaker amplitude suppression. As another velocity-dependent effect, we calculate the spectrum for s-wave annihilation into fermions enhanced by the attractive Sommerfeld effect. Resonances associated with this effect result in significantly enhanced intensities, with a slightly softer energy spectrum.

  9. The influence of chemical and color quenching on the shape of energy spectrum for Beta particles of 90Sr- 90Y by using liquid scintillation cocktail

    International Nuclear Information System (INIS)

    The effect of chemical quenching on the pulse height spectrum and Emax of Strontium 90Sr were studied using the organic scintillation cocktail and observing change in florescent yield and spectral shape (energy spectrum) of beta particles of 90Sr isotope in determining a relationship between the magnitude of material that causes quenching and the position of energy spectrum and Emax, adding 3 M nitric acid (HNO3) as chemical quencher to the scintillation, and added aqueous soluble yellow food dye with different concentration as color quencher. The beta detection efficiency depends on energy, spectral shape and cocktail. Typically, beta particles with maximum energies (Emax > 0.250 MeV) are detected with > 90% counting efficiency in organic liquid scintillation, where 90Sr has maximum beta energy, Emax, of 0.546 MeV and half-life of 28.17 years. The results were compared with reference and literature values. (author)

  10. Uniqueness verification of solar spectrum index of average photon energy for evaluating outdoor performance of photovoltaic modules

    Energy Technology Data Exchange (ETDEWEB)

    Minemoto, Takashi; Nakada, Yasuhito; Takahashi, Hiroaki; Takakura, Hideyuki [College of Science and Engineering, Ritsumeikan University, 1-1-1 Nojihigashi, Kusatsu, Shiga 525-8577 (Japan)

    2009-08-15

    To analyze the effect of a spectral irradiance distribution of solar spectra on the outdoor performance of photovoltaic (PV) modules, an index for the spectral distribution is needed. Average photon energy (APE) which represents the average energy per photons included in a spectrum is one of these. In this study, the uniqueness of APE to the spectral irradiance distribution was statistically analyzed to assure that an APE value uniquely yields the shape of a solar spectrum. The similar methodology adopted in International Electrotechnical Commission to rate the spectral matching of a solar simulator was used for the analysis. The results showed that an APE value yielded a spectral irradiance distribution with quite small standard deviation. The analysis using APE showed that the outdoor performance of crystalline Si PV modules depended almost only on a module temperature, while that of amorphous Si ones mainly depended on APE. The behaviors were reasonable considering from the operation mechanisms of the PV modules. These results demonstrate that APE is a reasonable and useful index to describe the spectral irradiance distribution for evaluating the outdoor performance of PV modules. (author)

  11. Off-axis holographic lens spectrum-splitting photovoltaic system for direct and diffuse solar energy conversion.

    Science.gov (United States)

    Vorndran, Shelby D; Chrysler, Benjamin; Wheelwright, Brian; Angel, Roger; Holman, Zachary; Kostuk, Raymond

    2016-09-20

    This paper describes a high-efficiency, spectrum-splitting photovoltaic module that uses an off-axis volume holographic lens to focus and disperse incident solar illumination to a rectangular shaped high-bandgap indium gallium phosphide cell surrounded by strips of silicon cells. The holographic lens design allows efficient collection of both direct and diffuse illumination to maximize energy yield. We modeled the volume diffraction characteristics using rigorous coupled-wave analysis, and simulated system performance using nonsequential ray tracing and PV cell data from the literature. Under AM 1.5 illumination conditions the simulated module obtained a 30.6% conversion efficiency. This efficiency is a 19.7% relative improvement compared to the more efficient cell in the system (silicon). The module was also simulated under a typical meteorological year of direct and diffuse irradiance in Tucson, Arizona, and Seattle, Washington. Compared to a flat panel silicon module, the holographic spectrum splitting module obtained a relative improvement in energy yield of 17.1% in Tucson and 14.0% in Seattle. An experimental proof-of-concept volume holographic lens was also fabricated in dichromated gelatin to verify the main characteristics of the system. The lens obtained an average first-order diffraction efficiency of 85.4% across the aperture at 532 nm.

  12. A new method of reconstructing very-high-energy gamma-ray spectra: the Template Background Spectrum

    CERN Document Server

    Fernandes, M V; Kosack, K; Raue, M; Rowell, G

    2014-01-01

    Very-high-energy (VHE, E>0.1 TeV) gamma-ray emission regions with angular extents comparable to the field-of-view of current imaging air-Cherenkov telescopes (IACT) require additional observations of source-free regions to estimate the background contribution to the energy spectrum. This reduces the effective observation time and deteriorates the sensitivity. A new method of reconstructing spectra from IACT data without the need of additional observations of source-free regions is developed. Its application is not restricted to any specific IACT or data format. On the basis of the template background method, which defines the background in air-shower parameter space, a new spectral reconstruction method from IACT data is developed and studied, the Template Background Spectrum (TBS); TBS is tested on published H.E.S.S. data and H.E.S.S. results. Good agreement is found between VHE gamma-ray spectra reported by the H.E.S.S. collaboration and those re-analysed with TBS. This includes analyses of point-like sourc...

  13. Off-axis holographic lens spectrum-splitting photovoltaic system for direct and diffuse solar energy conversion.

    Science.gov (United States)

    Vorndran, Shelby D; Chrysler, Benjamin; Wheelwright, Brian; Angel, Roger; Holman, Zachary; Kostuk, Raymond

    2016-09-20

    This paper describes a high-efficiency, spectrum-splitting photovoltaic module that uses an off-axis volume holographic lens to focus and disperse incident solar illumination to a rectangular shaped high-bandgap indium gallium phosphide cell surrounded by strips of silicon cells. The holographic lens design allows efficient collection of both direct and diffuse illumination to maximize energy yield. We modeled the volume diffraction characteristics using rigorous coupled-wave analysis, and simulated system performance using nonsequential ray tracing and PV cell data from the literature. Under AM 1.5 illumination conditions the simulated module obtained a 30.6% conversion efficiency. This efficiency is a 19.7% relative improvement compared to the more efficient cell in the system (silicon). The module was also simulated under a typical meteorological year of direct and diffuse irradiance in Tucson, Arizona, and Seattle, Washington. Compared to a flat panel silicon module, the holographic spectrum splitting module obtained a relative improvement in energy yield of 17.1% in Tucson and 14.0% in Seattle. An experimental proof-of-concept volume holographic lens was also fabricated in dichromated gelatin to verify the main characteristics of the system. The lens obtained an average first-order diffraction efficiency of 85.4% across the aperture at 532 nm. PMID:27661578

  14. The high energy X-ray spectrum of 4U 1700-37 observed from OSO 8

    Science.gov (United States)

    Dolan, J. F.; Coe, M. J.; Crannell, C. J.; Dennis, B. R.; Frost, K. J.; Orwig, L. E.; Maurer, G. S.

    1980-01-01

    The most intense hard X-ray source in the confused region in Scorpius has been identified as 4U 1700-37 (=HD 153919). Observations extending over three binary periods in 1978 September were carried out with the high-energy X-ray spectrometer on OSO 8. The 3.4 day modulation is seen above 20 keV with the intensity during eclipse being consistent with zero flux. The photonumber spectrum from 20 to 150 keV is well represented by a single power law with a photonumber spectral index of -2.77 + or - 0.35 or by a thermal bremsstrahlung spectrum with kT = 27 (+15, -7)keV. The counting rate above 20 keV outside of eclipse shows no evidence for the 96.8 minute X-ray modulation previously reported at lower energies. Despite the difficulties that exist in reconciling both the lack of periodic modulation in the emitted X-radiation and the orbital dynamics of the system with our currently accepted theories of the evolution and physical properties of neutron stars, the observed properties of 4U 1700-37 are all consistent with the source being a spherically accreting neutron star rather than a black hole.

  15. High-energy properties of the high-redshift flat spectrum radio quasar PKS 2149-306

    CERN Document Server

    D'Ammando, F

    2015-01-01

    We investigate the gamma-ray and X-ray properties of the flat spectrum radio quasar PKS 2149-306 at redshift z = 2.345. A strong gamma-ray flare from this source was detected by the Large Area Telescope on board the Fermi Gamma-ray Space Telescope satellite in 2013 January, reaching on January 20 a daily peak flux of (301$\\pm$36)$\\times$10$^{-8}$ ph/cm$^2$/s in the 0.1-100 GeV energy range. This flux corresponds to an apparent isotropic luminosity of (1.5$\\pm$0.2)$\\times$10$^{50}$ erg/s, comparable to the highest values observed by a blazar so far. During the flare the increase of flux was accompanied by a significant change of the spectral properties. Moreover significant flux variations on a 6-h time-scale were observed, compatible with the light crossing time of the event horizon of the central black hole. The broad band X-ray spectra of PKS 2149-306 observed by Swift-XRT and NuSTAR are well described by a broken power-law model, with a very hard spectrum ($\\Gamma$$_1$ $\\sim$ 1) below the break energy, at ...

  16. Energy spectrum of 50-250 MeV/nucleon iron nuclei inside the MIR space craft

    Energy Technology Data Exchange (ETDEWEB)

    Guenther, W. E-mail: guenther@hig.physik.uni_siegen.de; Leugner, D.; Becker, E.; Heinrich, W.; Reitz, G

    2002-10-01

    Stacks of CR-39 plastic nuclear track detectors were mounted inside the MIR spacecraft during the EUROMIR95 space mission for a period of 6 months. This long exposure time resulted in a large number of tracks of HZE-particles in the detector foils. All trajectories of stopping iron nuclei could be reconstructed by optimizing the etching conditions so that an automatic track measurement using image analysis techniques was possible. We found 185 stopping iron nuclei and used the energy-range relation to calculate their energies at the stack surface. The measured spectrum of iron nuclei inside the MIR station is compared to results of model predictions considering the effect of the solar modulation for the mission period, the geomagnetic shielding effect for the MIR orbit and the shielding by material of the spacecraft walls and its instrumentation.

  17. Measurement of the atmospheric muon neutrino energy spectrum with IceCube in the 79- and 86-String configuration

    Science.gov (United States)

    Ruhe, T.; Scheriau, F.; Schmitz, M.

    2016-04-01

    IceCube is a neutrino telescope with an instrumented volume of one cubic kilometer. A total of 5160 Digital Optical Modules (DOMs) is deployed on 86 strings forming a three dimensional detector array. Although primarily designed for the detection of neutrinos from astrophysical sources, the detector can be used for spectral measurements of atmospheric neutrinos. These spectral measurements are hindered by a dominant background of atmospheric muons. State-of-the-art techniques from Machine Learning and Data Mining are required to select a high-purity sample of atmospheric neutrino candidates. The energy spectrum of muon neutrinos is obtained from energy-dependent input variables by utilizing regularized unfolding. The results obtained using IceCube in the 79- and 86-string configuration are presented in this paper.

  18. Anisotropy of eddy variability in the global ocean

    Science.gov (United States)

    Stewart, K. D.; Spence, P.; Waterman, S.; Sommer, J. Le; Molines, J.-M.; Lilly, J. M.; England, M. H.

    2015-11-01

    The anisotropy of eddy variability in the global ocean is examined in geostrophic surface velocities derived from satellite observations and in the horizontal velocities of a 1/12° global ocean model. Eddy anisotropy is of oceanographic interest as it is through anisotropic velocity fluctuations that the eddy and mean-flow fields interact dynamically. This study is timely because improved observational estimates of eddy anisotropy will soon be available with Surface Water and Ocean Topography (SWOT) altimetry data. We find there to be good agreement between the characteristics and distributions of eddy anisotropy from the present satellite observations and model ocean surface. In the model, eddy anisotropy is found to have significant vertical structure and is largest close to the ocean bottom, where the anisotropy aligns with the underlying isobaths. The highly anisotropic bottom signal is almost entirely contained in the barotropic variability. Upper-ocean variability is predominantly baroclinic and the alignment is less sensitive to the underlying bathymetry. These findings offer guidance for introducing a parameterization of eddy feedbacks, based on the eddy kinetic energy and underlying bathymetry, to operate on the barotropic flow and better account for the effects of barotropic Reynolds stresses unresolved in coarse-resolution ocean models.

  19. In-Plane Optical Anisotropy of Layered Gallium Telluride.

    Science.gov (United States)

    Huang, Shengxi; Tatsumi, Yuki; Ling, Xi; Guo, Huaihong; Wang, Ziqiang; Watson, Garrett; Puretzky, Alexander A; Geohegan, David B; Kong, Jing; Li, Ju; Yang, Teng; Saito, Riichiro; Dresselhaus, Mildred S

    2016-09-27

    Layered gallium telluride (GaTe) has attracted much attention recently, due to its extremely high photoresponsivity, short response time, and promising thermoelectric performance. Different from most commonly studied two-dimensional (2D) materials, GaTe has in-plane anisotropy and a low symmetry with the C2h(3) space group. Investigating the in-plane optical anisotropy, including the electron-photon and electron-phonon interactions of GaTe is essential in realizing its applications in optoelectronics and thermoelectrics. In this work, the anisotropic light-matter interactions in the low-symmetry material GaTe are studied using anisotropic optical extinction and Raman spectroscopies as probes. Our polarized optical extinction spectroscopy reveals the weak anisotropy in optical extinction spectra for visible light of multilayer GaTe. Polarized Raman spectroscopy proves to be sensitive to the crystalline orientation of GaTe, and shows the intricate dependences of Raman anisotropy on flake thickness, photon and phonon energies. Such intricate dependences can be explained by theoretical analyses employing first-principles calculations and group theory. These studies are a crucial step toward the applications of GaTe especially in optoelectronics and thermoelectrics, and provide a general methodology for the study of the anisotropy of light-matter interactions in 2D layered materials with in-plane anisotropy.

  20. Large-scale anisotropy of the cosmic background radiation due to primordial density and gravitational-wave perturbations

    International Nuclear Information System (INIS)

    The possibility that part of the recently discovered large-scale anisotropy of the cosmic background radiation is aroused from primordial density and gravitational-wave perturbations through the Sachs-Wolfe effect, is investigated in both closed and open models in connection with the severe constraint for the small-scale anisotropy. It is concluded that, in order to explain the dipole anisotropy of the order of 10-3 by density perturbations, closed models and density fluctuation spectrums not steeper than ''white noise'' one are required, and that gravitational-wave perturbations cannot contribute to the possible quadrupole anisotropy of the order of 10-4. (author)

  1. MULTIMODE quantum calculations of vibrational energies and IR spectrum of the NO{sup +}(H{sub 2}O) cluster using accurate potential energy and dipole moment surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Homayoon, Zahra, E-mail: zhomayo@emory.edu [Cherry L. Emerson Center for Scientific Computation and Department of Chemistry, Emory University, Atlanta, Georgia 30322 (United States)

    2014-09-28

    A new, full (nine)-dimensional potential energy surface and dipole moment surface to describe the NO{sup +}(H{sub 2}O) cluster is reported. The PES is based on fitting of roughly 32 000 CCSD(T)-F12/aug-cc-pVTZ electronic energies. The surface is a linear least-squares fit using a permutationally invariant basis with Morse-type variables. The PES is used in a Diffusion Monte Carlo study of the zero-point energy and wavefunction of the NO{sup +}(H{sub 2}O) and NO{sup +}(D{sub 2}O) complexes. Using the calculated ZPE the dissociation energies of the clusters are reported. Vibrational configuration interaction calculations of NO{sup +}(H{sub 2}O) and NO{sup +}(D{sub 2}O) using the MULTIMODE program are performed. The fundamental, a number of overtone, and combination states of the clusters are reported. The IR spectrum of the NO{sup +}(H{sub 2}O) cluster is calculated using 4, 5, 7, and 8 modes VSCF/CI calculations. The anharmonic, coupled vibrational calculations, and IR spectrum show very good agreement with experiment. Mode coupling of the water “antisymmetric” stretching mode with the low-frequency intermolecular modes results in intensity borrowing.

  2. Energy Spectrum of a Positronium Negative Ion in a Parabolic Quantum Well

    Institute of Scientific and Technical Information of China (English)

    XIE Wen-Fang

    2002-01-01

    The method of few-body physics is applied to calculating the energy levels of low-lying states ofa positro-nium negative ion in a parabolic quantum well. The results show that the energy levels of a positronium negativeion intwo-dimensional case are lower than those in three-dimensional case.

  3. Energy Spectrum of a Positronium Negative Ion in a Parabolic Quantum Well

    Institute of Scientific and Technical Information of China (English)

    XIEWen-Fang

    2002-01-01

    The method of few-body physics is applied to calculating the energy levels of low-lying states of a positronium negative ion in a parabolic quantum well.The results show that the energy levels of a positronium negative ion in two-dimensional case are lower than those in three-dimensional case.

  4. Energy Spectrum of Two-Component Bose-Einstein Condensates in Optical Lattices

    Institute of Scientific and Technical Information of China (English)

    HAN Jiu-Rong; LIU Jin-Ming; JING Hui; WANG Yu-Zhu

    2005-01-01

    With the method of Green's function, we investigate the energy spectra of two-component ultracold bosonic atoms in optical lattices. We find that there are two energy bands for each component. The critical condition of the superfluid-Mott insulator phase transition is determined by the energy band structure. We also find that the nearest neighboring and on-site interactions fail to change the structure of energy bands, but shift the energy bands only.According to the conditions of the phase transitions, three stable superfluid and Mott insulating phases can be found by adjusting the experiment parameters. We also discuss the possibility of observing these new phases and their transitions in further experiments.

  5. Interferences in the photoelectron spectrum of H+2 molecules at high energy

    International Nuclear Information System (INIS)

    We present a theoretical study of ground state H+2 ionization by photons of a few hundreds of eV. Bound and continuum states are obtained by using B-spline basis functions. As predicted by Cohen and Fano [H.D. Cohen, U. Fano, Phys. Rev. 150 (1966) 30], the calculated photoelectron spectrum reveals the existence of interference effects that result from the coherent emission in the presence of the two nuclei. We show, however, that one of the basic assumption of the Cohen-Fano model, namely, the validity of the LCAO approximation to describe the initial ground state or the free wave description of the ejected electron, is not fulfilled, which leads to an 'anomalous' oscillatory behavior not pointed out in previous works

  6. Laser diagnostics of the energy spectrum of Rydberg states of the lithium-7 atom

    Energy Technology Data Exchange (ETDEWEB)

    Zelener, B. B., E-mail: bobozel@mail.ru; Saakyan, S. A.; Sautenkov, V. A.; Manykin, E. A.; Zelener, B. V.; Fortov, V. E. [Russian Academy of Sciences, Joint Institute for High Temperatures (Russian Federation)

    2015-12-15

    The spectra of excited lithium-7 atoms prepared in a magneto-optical trap are studied using a UV laser. The laser diagnostics of the energy of Rydberg atoms is developed based on measurements of the change in resonance fluorescence intensity of ultracold atoms as the exciting UV radiation frequency passes through the Rydberg transition frequency. The energies of various nS configurations are obtained in a broad range of the principal quantum number n from 38 to 165. The values of the quantum defect and ionization energy obtained in experiments and predicted theoretically are discussed.

  7. Ion acceleration with a narrow energy spectrum by nanosecond laser-irradiation of solid target

    Energy Technology Data Exchange (ETDEWEB)

    Altana, C., E-mail: altana@lns.infn.it [Laboratori Nazionali del Sud, Istituto Nazionale di Fisica Nucleare, Via S. Sofia 62, 95123 Catania (Italy); Dipartimento di Fisica e Astronomia, Università degli Studi di Catania, Via S. Sofia 64, 95123 Catania (Italy); Lanzalone, G. [Laboratori Nazionali del Sud, Istituto Nazionale di Fisica Nucleare, Via S. Sofia 62, 95123 Catania (Italy); Università degli Studi di Enna “Kore,” Via delle Olimpiadi, 94100 Enna (Italy); Mascali, D.; Cirrone, G. A. P.; Schillaci, F.; Tudisco, S. [Laboratori Nazionali del Sud, Istituto Nazionale di Fisica Nucleare, Via S. Sofia 62, 95123 Catania (Italy); Muoio, A. [Laboratori Nazionali del Sud, Istituto Nazionale di Fisica Nucleare, Via S. Sofia 62, 95123 Catania (Italy); Dipartimento di Fisica e Scienze della Terra, Università degli Studi di Messina, Viale F. D’Alcontres 31, 98166 Messina (Italy)

    2016-02-15

    In laser-driven plasma, ion acceleration of aluminum with the production of a quasi-monoenergetic beam has occurred. A useful device to analyze the ions is the Thomson parabolas spectrometer, a well-known diagnostic that is able to obtain information on charge-to-mass ratio and energy distribution of the charged particles. At the LENS (Laser Energy for Nuclear Science) laboratory of INFN-LNS in Catania, experimental measures were carried out; the features of LENS are: Q-switched Nd:YAG laser with 2 J laser energy, 1064 nm fundamental wavelengths, and 6 ns pulse duration.

  8. Low-frequency ionospheric sounding with Narrow Bipolar Event lightning radio emissions: energy-reflectivity spectrum

    Directory of Open Access Journals (Sweden)

    A. R. Jacobson

    2008-06-01

    Full Text Available We analyze data on radio-reflection from the D-region of the lower ionosphere, retrieving the energy-reflection coefficient in the frequency range ~5–95 kHz. The data are the same as developed for a recent study of ionospheric-reflection height, and are based on recordings of powerful (multi-Gigawatt radio emissions from a type of narrow (~10 μs lightning discharge known as "Narrow Bipolar Events". The sequential appearance of first the groundwave signal, and then the ionospheric single-hop reflection signal, permits us to construct the energy-reflection ratio. We infer the energy reflection's statistical variation with solar zenith angle, angle-of-incidence, frequency, and propagation azimuth. There is also a marginally-significant response of the energy reflectivity to solar X-ray flux density. Finally, we review the relationship of our results to previous published reports.

  9. Effects of trapped proton flux anisotropy on dose rates in low Earth orbit.

    Science.gov (United States)

    Badhwar, G D; Kushin, V V; Akatov YuA; Myltseva, V A

    1999-06-01

    Trapped protons in the South Atlantic Anomaly (SAA) have a rather narrow pitch angle distribution and exhibit east-west anisotropy. In low Earth orbits, the E-W effect results in different amounts of radiation dose received by different sections of the spacecraft. This effect is best studied on missions in which the spacecraft flies in a fixed orientation. The magnitude of the effect depends on the particle energy and altitude through the SAA. In this paper, we describe a clear example of this effect from measurements of radiation dose rates and linear energy transfer spectra made on Space Shuttle flight STS-94 (28.5 degree inclination x 296 km altitude). The ratio of dose rates from the two directions at this location in the mid-deck was 2.7. As expected from model calculations, the spectra from the two directions are different, that is the ratio is energy dependent. The data can be used to distinguish the anisotropy models. The flight carried an active tissue equivalent proportional counter (TEPC), and passive thermoluminscent detectors (TLDs), and two types of nuclear emulsions. Using nuclear emulsions, charged particles and secondary neutron energy spectra were measured. The combined galactic cosmic radiation+trapped charged particle lineal energy spectra measured by the TEPC and the linear energy transfer spectrum measured by nuclear emulsions are in good agreement. The charged particle absorbed dose rates varied from 112 to 175 microGy/day, and dose equivalent rates from 264.3 to 413 microSv/day. Neutrons in the 1-10 MeV contributed a dose rate of 3.7 microGy/day and dose equivalent rate of 30.8 microSv/day, respectively. PMID:11543145

  10. Quantum Geometry: Relativistic energy approach to cooperative electron-nucleary-transition spectrum

    Directory of Open Access Journals (Sweden)

    Ольга Юрьевна Хецелиус

    2014-11-01

    Full Text Available An advanced relativistic energy approach is presented and applied to calculating parameters of electron-nuclear 7-transition spectra of nucleus in the atom. The intensities of the spectral satellites are defined in the relativistic version of the energy approach (S-matrix formalism, and gauge-invariant quantum-electrodynamical perturbation theory with the Dirac-Kohn-Sham density-functional zeroth approximation.

  11. The Energy Spectrum of the Blazar Markarian 421 Above 130 GeV

    CERN Document Server

    Carson, J E; Ong, R A; Ball, J; Bramel, D A; Covault, C E; Driscoll, D; Fortin, P; Gingrich, D M; Hanna, D S; Lindner, T; Müller, C; Jarvis, A; Mukherjee, R; Ragan, K; Scalzo, R A; Williams, D A; Zweerink, J

    2006-01-01

    Markarian 421 (Mrk 421) was the first blazar detected at gamma-ray energies above 300 GeV, and it remains one of only twelve TeV blazars detected to date. TeV gamma-ray measurements of its flaring activity and spectral variability have placed constraints on models of the high-energy emission from blazars. However, observations between 50 and 300 GeV are rare, and the high-energy peak of the spectral energy distribution (SED), predicted to be in this range, has never been directly detected. We present a detection of Mrk 421 above 100 GeV as made by the Solar Tower Atmospheric Cherenkov Effect Experiment (STACEE) during a multiwavelength campaign in early 2004. STACEE is a ground-based atmospheric Cherenkov telescope using the wavefront sampling technique to detect gamma rays at lower energies than achieved by most imaging Cherenkov telescopes. We also outline a method for reconstructing gamma-ray energies using a solar heliostat telescope. This technique was applied to the 2004 data, and we present the differe...

  12. HESS J1427-608: an unusual hard unbroken $\\gamma-$ray spectrum in a very wide energy range

    CERN Document Server

    Guo, Xiao-Lei; Liao, Neng-Hui; Yuan, Qiang; Gao, Wei-Hong; Fan, Yi-Zhong; Liu, Si-Ming

    2016-01-01

    We report the detection of a GeV $\\gamma$-ray source which is likely associated with the unidentified very-high-energy (VHE) $\\gamma$-ray source HESS J1427-608 with the Pass 8 data recorded by the Fermi Large Area Telescope. The photon spectrum of this source is best described by a power-law with an index of $1.85\\pm0.17$ in the energy range of $3-500$ GeV, and the measured flux connects smoothly with that of HESS J1427-608 at a few hundred GeV. This source shows no significant extended morphology and time variation. The broadband GeV-TeV emission over four decades of energies can be well fitted by a single power-law function with an index of 2.0, without obvious indication of spectral cutoff toward high energies. Such a result implies that HESS J1427-608 may be a PeV particle accelerator. We discuss possible nature of HESS J1427-608 according to the multi-wavelength spectral fittings. Given the relatively large errors, either a leptonic or a hadronic model can explain the multi-wavelength data from radio to ...

  13. Friction anisotropy in boronated graphite

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, N., E-mail: niranjan@igcar.gov.in [Materials Science Group, Indira Gandhi Centre for Atomic Research, Kalpakkam (India); Radhika, R. [Crystal Growth Centre, Anna University, Chennai (India); Kozakov, A.T. [Research Institute of Physics, Southern Federal University, Rostov-on-Don (Russian Federation); Pandian, R. [Materials Science Group, Indira Gandhi Centre for Atomic Research, Kalpakkam (India); Chakravarty, S. [UGC-DAE CSR, Kalpakkam (India); Ravindran, T.R.; Dash, S.; Tyagi, A.K. [Materials Science Group, Indira Gandhi Centre for Atomic Research, Kalpakkam (India)

    2015-01-01

    Graphical abstract: - Highlights: • Friction anisotropy in boronated graphite is observed in macroscopic sliding condition. • Low friction coefficient is observed in basal plane and becomes high in prismatic direction. • 3D phase of boronated graphite transformed into 2D structure after friction test. • Chemical activity is high in prismatic plane forming strong bonds between the sliding interfaces. - Abstract: Anisotropic friction behavior in macroscopic scale was observed in boronated graphite. Depending upon sliding speed and normal loads, this value was found to be in the range 0.1–0.35 in the direction of basal plane and becomes high 0.2–0.8 in prismatic face. Grazing-incidence X-ray diffraction analysis shows prominent reflection of (0 0 2) plane at basal and prismatic directions of boronated graphite. However, in both the wear tracks (1 1 0) plane become prominent and this transformation is induced by frictional energy. The structural transformation in wear tracks is supported by micro-Raman analysis which revealed that 3D phase of boronated graphite converted into a disordered 2D lattice structure. Thus, the structural aspect of disorder is similar in both the wear tracks and graphite transfer layers. Therefore, the crystallographic aspect is not adequate to explain anisotropic friction behavior. Results of X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy shows weak signature of oxygen complexes and functional groups in wear track of basal plane while these species dominate in prismatic direction. Abundance of these functional groups in prismatic plane indicates availability of chemically active sites tends to forming strong bonds between the sliding interfaces which eventually increases friction coefficient.

  14. Friction anisotropy in boronated graphite

    International Nuclear Information System (INIS)

    Graphical abstract: - Highlights: • Friction anisotropy in boronated graphite is observed in macroscopic sliding condition. • Low friction coefficient is observed in basal plane and becomes high in prismatic direction. • 3D phase of boronated graphite transformed into 2D structure after friction test. • Chemical activity is high in prismatic plane forming strong bonds between the sliding interfaces. - Abstract: Anisotropic friction behavior in macroscopic scale was observed in boronated graphite. Depending upon sliding speed and normal loads, this value was found to be in the range 0.1–0.35 in the direction of basal plane and becomes high 0.2–0.8 in prismatic face. Grazing-incidence X-ray diffraction analysis shows prominent reflection of (0 0 2) plane at basal and prismatic directions of boronated graphite. However, in both the wear tracks (1 1 0) plane become prominent and this transformation is induced by frictional energy. The structural transformation in wear tracks is supported by micro-Raman analysis which revealed that 3D phase of boronated graphite converted into a disordered 2D lattice structure. Thus, the structural aspect of disorder is similar in both the wear tracks and graphite transfer layers. Therefore, the crystallographic aspect is not adequate to explain anisotropic friction behavior. Results of X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy shows weak signature of oxygen complexes and functional groups in wear track of basal plane while these species dominate in prismatic direction. Abundance of these functional groups in prismatic plane indicates availability of chemically active sites tends to forming strong bonds between the sliding interfaces which eventually increases friction coefficient

  15. Fission Spectrum

    Science.gov (United States)

    Bloch, F.; Staub, H.

    1943-08-18

    Measurements of the spectrum of the fission neutrons of 25 are described, in which the energy of the neutrons is determined from the ionization produced by individual hydrogen recoils. The slow neutrons producing fission are obtained by slowing down the fast neutrons from the Be-D reaction of the Stanford cyclotron. In order to distinguish between fission neutrons and the remaining fast cyclotron neutrons both the cyclotron current and the pusle amplifier are modulated. A hollow neutron container, in which slow neutrons have a lifetime of about 2 milliseconds, avoids the use of large distances. This method results in much higher intensities than the usual modulation arrangement. The results show a continuous distribution of neutrons with a rather wide maximum at about 0.8 MV falling off to half of its maximum value at 2.0 MV. The total number of netrons is determined by comparison with the number of fission fragments. The result seems to indicate that only about 30% of the neutrons have energies below .8 MV. Various tests are described which were performed in order to rule out modification of the spectrum by inelastic scattering. Decl. May 4, 1951

  16. Single-ion anisotropy in the gadolinium pyrochlores studied by electron paramagnetic resonance

    Science.gov (United States)

    Glazkov, V. N.; Zhitomirsky, M. E.; Smirnov, A. I.; Krug von Nidda, H.-A.; Loidl, A.; Marin, C.; Sanchez, J.-P.

    2005-07-01

    The electron paramagnetic resonance is used to measure the single-ion anisotropy of Gd3+ ions in the pyrochlore structure of (Y1-xGdx)2Ti2O7 . A rather strong easy-plane-type anisotropy is found. The anisotropy constant D is comparable to the exchange integral J in the prototype Gd2Ti2O7 , D≃0.75J , and exceeds the dipolar energy scale. Physical implications of an easy-plane anisotropy for a pyrochlore antiferromagnet are considered. We calculate the magnetization curves at T=0 and discuss phase transitions in a magnetic field.

  17. Numerical experiments on the detailed energy conversion and spectrum studies in a corona current sheet

    CERN Document Server

    Ni, Lei; Mei, Zhixing; Li, Yan

    2015-01-01

    In this paper, we study the energy conversion and spectra in a corona current sheet by 2.5-dimensional MHD numerical simulations. Numerical results show that many Petschek-like fine structures with slow-mode shocks mediated by plasmoid instabilities develop during the magnetic reconnection process. The termination shocks can also be formed above the primary magnetic island and at the head of secondary islands. These shocks play important roles in generating thermal energy in a corona current sheet. For a numerical simulation with initial conditions close to the solar corona environment, the ratio of the generated thermal energy to the total dissipated magnetic energy is around $1/5$ before secondary islands appear. After secondary islands appear, the generated thermal energy starts to increase sharply and this ratio can reach a value about $3/5$. In an environment with a relatively lower plasma density and plasma $\\beta$, the plasma can be heated to a much higher temperature. After secondary islands appear, t...

  18. Proton temperature-anisotropy-driven instabilities in weakly collisional plasmas: Hybrid simulations

    CERN Document Server

    Hellinger, Petr

    2014-01-01

    Kinetic instabilities in weakly collisional, high beta plasmas are investigated using two-dimensional hybrid expanding box simulations with Coulomb collisions modeled through the Langevin equation (corresponding to the Fokker-Planck one). The expansion drives a parallel or perpendicular temperature anisotropy (depending on the orientation of the ambient magnetic field). For the chosen parameters the Coulomb collisions are important with respect to the driver but are not strong enough to keep the system stable with respect to instabilities driven by the proton temperature anisotropy. In the case of the parallel temperature anisotropy the dominant oblique fire hose instability efficiently reduces the anisotropy in a quasilinear manner. In the case of the perpendicular temperature anisotropy the dominant mirror instability generates coherent compressive structures which scatter protons and reduce the temperature anisotropy. For both the cases the instabilities generate temporarily enough wave energy so that the ...

  19. Time evolution of the anisotropies of the hydrodynamically expanding sQGP

    CERN Document Server

    Bagoly, Attila

    2015-01-01

    In high energy heavy ion collisions of RHIC and LHC, a strongly interacting quark gluon plasma (sQGP) is created. This medium undergoes a hydrodynamic evolution, before it freezes out to form a hadronic matter. The initial state of the sQGP is determined by the initial distribution of the participating nucleons and their interactions. Due to the finite number of nucleons, the initial distribution fluctuates on an event-by-event basis. The transverse plane anisotropy of the initial state can be translated into a series of anisotropy coefficients or eccentricities: second, third, fourth-order anisotropy etc. These anisotropies then evolve in time, and result in measurable momentum-space anisotropies, to be measured with respect to their respective symmetry planes. In this paper we investigate the time evolution of the anisotropies. With a numerical hydrodynamic code, we analyze how the speed of sound and viscosity influence this evolution.

  20. Spin confinement by anisotropy modulation

    Energy Technology Data Exchange (ETDEWEB)

    Bland, J.A.C. [Cavendish Laboratory, University of Cambridge, Cambridge (United Kingdom)]. E-mail: jacb1@phy.cam.ac.uk; Lew, W.S.; Li, S.P.; Lopez-Diaz, L.; Vaz, C.A.F. [Cavendish Laboratory, University of Cambridge, Cambridge (United Kingdom); Natali, M.; Chen, Y. [Laboratoire de Photonique et de Nanostructures, CNRS-LPN, Marcoussis (France)

    2002-10-07

    The spin configuration in a magnet is in general a 'natural' consequence of both the intrinsic properties of the material and the sample dimensions. We demonstrate that this limitation can be overcome in a homogeneous ferromagnetic film by engineering an anisotropy contrast. Substrates with laterally modulated single-crystal and polycrystalline surface regions were used to induce selective epitaxial growth of a ferromagnetic Ni film. The resulting spatially varying magnetic anisotropy leads to regular perpendicular and in-plane magnetic domains, separated by a new type of magnetic domain wall-the 'anisotropy constrained' magnetic wall. Micromagnetic simulations indicate that the wall is asymmetric, has a small out-of-plane component and has no mobility under external perturbation. (author)

  1. Spin confinement by anisotropy modulation

    Science.gov (United States)

    Bland, J. A. C.; Lew, W. S.; Li, S. P.; Lopez-Diaz, L.; Vaz, C. A. F.; Natali, M.; Chen, Y.

    2002-10-01

    The spin configuration in a magnet is in general a `natural' consequence of both the intrinsic properties of the material and the sample dimensions. We demonstrate that this limitation can be overcome in a homogeneous ferromagnetic film by engineering an anisotropy contrast. Substrates with laterally modulated single-crystal and polycrystalline surface regions were used to induce selective epitaxial growth of a ferromagnetic Ni film. The resulting spatially varying magnetic anisotropy leads to regular perpendicular and in-plane magnetic domains, separated by a new type of magnetic domain wall-the `anisotropy constrained' magnetic wall. Micromagnetic simulations indicate that the wall is asymmetric, has a small out-of-plane component and has no mobility under external perturbation.

  2. Ankle-like Feature in the Energy Spectrum of Light Elements of Cosmic Rays Observed with KASCADE-Grande

    CERN Document Server

    Apel, W D; Bekk, K; Bertaina, M; Blümer, J; Bozdog, H; Brancus, I M; Cantoni, E; Chiavassa, A; Cossavella, F; Daumiller, K; de Souza, V; Di Pierro, F; Doll, P; Engel, R; Engler, J; Finger, M; Fuchs, B; Fuhrmann, D; Gils, H J; Glasstetter, R; Grupen, C; Haungs, A; Heck, D; Hörandel, J R; Huber, D; Huege, T; Kampert, K -H; Kang, D; Klages, H O; Link, K; Łuczak, P; Ludwig, M; Mathes, H J; Mayer, H J; Melissas, M; Milke, J; Mitrica, B; Morello, C; Oehlschläger, J; Ostapchenko, S; Palmieri, N; Petcu, M; Pierog, T; Rebel, H; Roth, M; Schieler, H; Schoo, S; Schröder, F G; Sima, O; Toma, G; Trinchero, G C; Ulrich, H; Weindl, A; Wochele, J; Wommer, M; Zabierowski, J; 10.1103/PhysRevD.87.081101

    2013-01-01

    Recent results of the KASCADE-Grande experiment provided evidence for a mild knee-like structure in the all-particle spectrum of cosmic rays at $E = 10^{16.92 \\pm 0.10} \\, \\mathrm{eV}$, which was found to be due to a steepening in the flux of heavy primary particles. The spectrum of the combined components of light and intermediate masses was found to be compatible with a single power law in the energy range from $10^{16.3} \\, \\mathrm{eV}$ to $10^{18} \\, \\mathrm{eV}$. In this paper, we present an update of this analysis by using data with increased statistics, originating both from a larger data set including more recent measurements and by using a larger fiducial area. In addition, optimized selection criteria for enhancing light primaries are applied. We find a spectral feature for light elements, namely a hardening at $E = 10^{17.08 \\pm 0.08} \\, \\mathrm{eV}$ with a change of the power law index from $-3.25 \\pm 0.05$ to $-2.79 \\pm 0.08$.

  3. The High Energy X-ray Spectrum of 4U1700-37 Observed from OSO-8

    Science.gov (United States)

    Dolan, J. F.; Coe, M. J.; Crannell, C. J.; Dennis, B. R.; Frost, K. J.; Maurer, G. S.; Orwig, L. E.

    1979-01-01

    The most intense hard X-ray source in the confused region in Scorpius is identified as 4U1700-37. The 3.4-day modulation is seen above 20 keV with the intensity during eclipse being consistent with zero flux. The photon-number spectrum from 20 to 150 keV is well represented by a single power law with a photo-number spectral index of -2.77 + or - 0.35 or by a thermal bremsstrahlung spectrum with kT = 27 96.8-min X-ray modulation previously reported at lower energies. Despite the difficulties in reconciling both the lack of periodic modulation in the emitted X-radiation and the orbital dynamics of the system with theories of the evolution and physical properties of neutron stars, the observed properties of 4U1700-37 are all consistent with the source being a spherically accreting neutron star rather than a black hole.

  4. Ankle-like feature in the energy spectrum of light elements of cosmic rays observed with KASCADE-Grande

    Science.gov (United States)

    Apel, W. D.; Arteaga-Velàzquez, J. C.; Bekk, K.; Bertaina, M.; Blümer, J.; Bozdog, H.; Brancus, I. M.; Cantoni, E.; Chiavassa, A.; Cossavella, F.; Daumiller, K.; de Souza, V.; Di Pierro, F.; Doll, P.; Engel, R.; Engler, J.; Finger, M.; Fuchs, B.; Fuhrmann, D.; Gils, H. J.; Glasstetter, R.; Grupen, C.; Haungs, A.; Heck, D.; Hörandel, J. R.; Huber, D.; Huege, T.; Kampert, K.-H.; Kang, D.; Klages, H. O.; Link, K.; Łuczak, P.; Ludwig, M.; Mathes, H. J.; Mayer, H. J.; Melissas, M.; Milke, J.; Mitrica, B.; Morello, C.; Oehlschläger, J.; Ostapchenko, S.; Palmieri, N.; Petcu, M.; Pierog, T.; Rebel, H.; Roth, M.; Schieler, H.; Schoo, S.; Schröder, F. G.; Sima, O.; Toma, G.; Trinchero, G. C.; Ulrich, H.; Weindl, A.; Wochele, J.; Wommer, M.; Zabierowski, J.

    2013-04-01

    Recent results of the KASCADE-Grande experiment provided evidence for a mild knee-like structure in the all-particle spectrum of cosmic rays at E=1016.92±0.10eV, which was found to be due to a steepening in the flux of heavy primary particles. The spectrum of the combined components of light and intermediate masses was found to be compatible with a single power law in the energy range from 1016.3 to 1018eV. In this paper, we present an update of this analysis by using data with increased statistics, originating both from a larger data set including more recent measurements and by using a larger fiducial area. In addition, optimized selection criteria for enhancing light primaries are applied. We find a spectral feature for light elements, namely, a hardening at E=1017.08±0.08eV with a change of the power law index from -3.25±0.05 to -2.79±0.08.

  5. Propagation of high-energy cosmic rays in extragalactic turbulent magnetic fields: resulting energy spectrum and composition

    CERN Document Server

    Globus, N; Parizot, E

    2007-01-01

    We extend previous studies of mixed-composition extragalactic cosmic-ray source models, by investigating the influence of a non-negligible extragalactic magnetic field on the propagated cosmic-ray spectrum and composition. We study the transport of charged particles in turbulent fields and the transition from a ballistic to a diffusive propagation regime. We introduce a method allowing a fast integration of the particle trajectories, which allows us to calculate extragalactic cosmic-ray spectra in the general case, without using either the diffusive or the rectilinear approximation. We find that the main features of the mixed-composition models -- regarding the interpretation of the ankle and the non-monotonous evolution of the average cosmic-ray mass -- remain essentially unchanged as long as the magnetic field intensity does not exceed a few nG.

  6. Obscured flat spectrum radio AGN as sources of high-energy neutrinos

    OpenAIRE

    Maggi, G.; Buitink, S.; Correa, P; De Vries, K. D.; Gentile, G.; Tavares, J. Leon; Scholten, O.; van Eijndhoven, N.; Vereecken, M.; Winchen, T.

    2016-01-01

    Active Galactic Nuclei (AGN) are believed to be one of the main source candidates for the high-energy (TeV-PeV) cosmic neutrino flux recently discovered by the IceCube neutrino observatory. Nevertheless, several correlation studies between AGN and the cosmic neutrinos detected by IceCube show no significance. Therefore, in this article we consider a specific sub-class of AGN for which an increased neutrino production is expected. This sub-class contains AGN for which their high-energy jet is ...

  7. Optimal Energy-Efficient Cooperative Spectrum Sensing in Cognitive Radio Networks

    Directory of Open Access Journals (Sweden)

    Z. Zhang

    2013-12-01

    Full Text Available Inspired by the green communication trend of next-generation wireless networks, we select energy-efficient throughput as optimization metric for jointly optimizing sensing time and working sensors in cooperative cognitive radio networks. Specifically, an iterative algorithm is proposed to obtain the optimal values for these two parameters. Specifically, the proposed iterative algorithm is low complexity when compares to the exhaustive search method, and very easy to be implemented. Finally, simulation results reveal that the proposed optimization improves the energy-efficient throughput significantly when the sensing time and working sensors are jointly optimized.

  8. Phenomenological description of anisotropy effects in some ferromagnetic superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Shopova, Diana V., E-mail: sho@issp.bas.bg [TCCM Research Group, Institute of Solid State Physics, Bulgarian Academy of Sciences, BG-1784 Sofia (Bulgaria); Todorov, Michail D. [Department of Applied Mathematics and Computer Science, Technical University of Sofia, 1000 Sofia (Bulgaria)

    2015-07-03

    We study phenomenologically the role of anisotropy in ferromagnetic superconductors UGe{sub 2}, URhGe, and UCoGe for the description of their phase diagrams. We use the Ginzburg–Landau free energy in its uniform form as we will consider only spatially independent solutions. This is an expansion of previously derived results where the effect of Cooper-pair and crystal anisotropies is not taken into account. The three compounds are separately discussed with the special stress on UGe{sub 2}. The main effect comes from the strong uniaxial anisotropy of magnetization while the anisotropy of Cooper pairs and crystal anisotropy only slightly change the phase diagram in the vicinity of Curie temperature. The limitations of this approach are also discussed. - Highlights: • Anisotropic Landau energy for description of ferromagnetic superconductors is proposed. • Meissner phases are described with their existence and stability conditions. • The application of the model to UGe{sub 2} is discussed. • The limitations to apply the model for description of experimental data are explained.

  9. The effect of the geomagnetic field on cosmic ray energy estimates and large scale anisotropy searches on data from the Pierre Auger Observatory

    OpenAIRE

    Arganda, E.; Arqueros Martínez, Fernando; Blanco Ramos, Francisco; García Pinto, Diego; Ortiz Ramis, Montserrat; Rosado Vélez, Jaime; Vázquez Peñas, José Ramón

    2011-01-01

    We present a comprehensive study of the influence of the geomagnetic field on the energy estimation of extensive air showers with a zenith angle smaller than 60 degrees, detected at the Pierre Auger Observatory. the geomagnetic field induces an azimuthal modulation of the estimated energy of cosmic rays up to the similar to 2% level at large zenith angles. We present a method to account for this modulation of the reconstructed energy. We analyse the effect of the modulation on large scale ani...

  10. Amiba Observation of CMB Anisotropies

    Science.gov (United States)

    Ng, Kin-Wang

    2003-03-01

    The Array for Microwave Background Anisotropies (AMiBA), a 13-element dual-channel 85-105 GHz interferometer array with full polarization capabilities, is being built to search for high redshift clusters of galaxies via the Sunyaev-Zel'dovich effect as well as to probe the polarization properties of the cosmic microwave background (CMB). We discuss several important issues in the observation of the CMB anisotropies such as observing strategy, l space resolution and mosaicing, optimal estimation of the power spectra, and ground pickup removal.

  11. High energy x-ray reflectivity and scattering study from spectrum-x-gamma flight mirrors

    DEFF Research Database (Denmark)

    Christensen, Finn Erland; Budtz-Jørgensen, Carl; Frederiksen, P. Kk;

    1993-01-01

    Line radiation from Fe K-alpha(1), Cu K-alpha(1), and Ag K-alpha(1) is used to study the high energy X-ray reflectivity and scattering behavior of flight-quality X-ray mirrors having various Al substrates. When both the specular and the scattered radiation are integrated, near theoretical...

  12. On the infimum of the energy-momentum spectrum of a homogeneous Bose gas

    DEFF Research Database (Denmark)

    Cornean, Horia; Derezinski, J.; Zin, P.

    We consider second quantized homogeneous Bose gas in a large cubic box with periodic boundary conditions, at zero temperature, and in the grand canonical setting (the chemical potential μ is fixed, the number of particles can vary). We investigate upper bounds on the infimum of the energy for a...

  13. Energy spectrum of 50-250 MeV/nucleon iron nuclei inside the MIR space craft.

    Science.gov (United States)

    Gunther, W; Leugner, D; Becker, E; Heinrich, W; Reitz, G

    2002-10-01

    Stacks of CR-39 plastic nuclear track detectors were mounted inside the MIR spacecraft during the EUROMIR95 space mission for a period of 6 months. This long exposure time resulted in a large number of tracks of HZE-particles in the detector foils. All trajectories of stopping iron nuclei could be reconstructed by optimizing the etching conditions so that an automatic track measurement using image analysis techniques was possible. We found 185 stopping iron nuclei and used the énergy-range relation to calculate their energies at the stack surface. The measured spectrum of iron nuclei inside the MIR station is compared to results of model predictions considering the effect of the solar modulation for the mission period, the geomagnetic shielding effect for the MIR orbit and the shielding by material of the spacecraft walls and its instrumentation.

  14. Letter to the Editor Energy spectrum of secondary protons above the atmosphere measured by the instruments NINA and NINA-2

    Directory of Open Access Journals (Sweden)

    P. Papini

    Full Text Available In this paper we report on the energy spectrum of protons of albedo origin measured by the instruments NINA and NINA-2 at different geomagnetic locations, and the behaviour of the proton flux as a function of altitude out of the South Atlantic Anomaly. The instrument NINA was used on board the satellite Resurs-01-N4 between 1998 and 1999, at an altitude of about 830 km. The NINA-2 apparatus, on board the satellite MITA, was put into orbit in July 2000, at an altitude of about 450 km. A detailed understanding of the fluxes of charged particles in near Earth orbit is important to reach an accurate theoretical description of the Earth’s magnetic field, but also as input for the calculation of the back-ground for scientific instruments aboard satellites, like the future AGILE and GLAST g astronomy telescopes.Key words. Magnetospheric physics (energetic particles, trapped; instruments and techniques

  15. Modeling of the Signal Formation in SiC Sensors for Measurements of the Radiation Spectrum in Nuclear Energy

    International Nuclear Information System (INIS)

    The modeling methodology of the signal formation in SiC sensors is presented. The modeling uses two approaches: the first one is the integrated approach whereas the second is the analytical approach. The sensor response is obtained from both approaches: this is the usual solution of the forward problem. Moreover, the response function of the sensor is evaluated by means of the analytical approach and it can be used to solve the inverse problem: recovering the primary radiation spectrum using the response of the sensor. Additionally, the response function returns information about the signal formation in the sensor such as the shape of the response formed by particles with a specific energy. Results obtained by simulations are then compared with experimental data. (authors)

  16. Searches for Cosmic-Ray Electron Anisotropies with the \\textit{Fermi} Large Area Telescope

    CERN Document Server

    Ackermann, M

    2010-01-01

    The Large Area Telescope on board the \\textit{Fermi} satellite (\\textit{Fermi}-LAT) detected more than 1.6 million cosmic-ray electrons/positrons with energies above 60 GeV during its first year of operation. The arrival directions of these events were searched for anisotropies of angular scale extending from $\\sim$ 10 $^\\circ$ up to 90$^\\circ$, and of minimum energy extending from 60 GeV up to 480 GeV. Two independent techniques were used to search for anisotropies, both resulting in null results. Upper limits on the degree of the anisotropy were set that depended on the analyzed energy range and on the anisotropy's angular scale. The upper limits for a dipole anisotropy ranged from $\\sim0.5%$ to $\\sim5%$.

  17. Large Proton Anisotropies in the 18 August 2010 Solar Particle Event

    Science.gov (United States)

    Leske, R. A.; Cohen, C. M. S.; Mewaldt, R. A.; Christian, Eric R.; Cummings, A. C.; Labrador, A. W.; Stone, E. C.; Wiedenbeck, Mark E.; Rosenvinge, Tycho T Von

    2012-01-01

    The solar particle event observed at STEREO Ahead on 18 August 2010 displayeda rich variety of behavior in the particle anisotropies. Sectored rates measured by theLow Energy Telescope (LET) on STEREO showed very large bidirectional anisotropies in4 6 MeV protons for the first 17 hours of the event while inside a magnetic cloud, withintensities along the field direction several hundred to nearly 1000 times greater than thoseperpendicular to the field. At the trailing end of the cloud, the protons became isotropic andtheir spectrum hardened slightly, while the HeH abundance ratio plunged by a factor of approximatelyfour for about four hours. Associated with the arrival of a shock on 20 Augustwas a series of brief (10 minute duration) intensity increases (commonly called shockspikes) with relatively narrow angular distributions (45 FWHM), followed by an abruptdecrease in particle intensities at the shock itself and a reversal of the proton flow to a directiontoward the Sun and away from the receding shock. We discuss the STEREOLETobservations of this interesting event in the context of other observations reported in theliterature

  18. Quantum Breathers in Anisotropy Ferromagnetic Chains with Second-Order Coupling

    Science.gov (United States)

    Tang, Bing

    2016-08-01

    Under considering the next-nearest-neighbor interaction, quantum breathers in one-dimensional anisotropy ferromagnetic chains are theortically studied. By introducing the Dyson-Maleev transformation for spin operators, a map to a Heisenberg ferromagnetic spin lattice into an extended Bose-Hubbard model can be established. In the case of a small number of bosons, by means of the numerical diagonalization technique, the energy spectrum of the corresponding extended Bose-Hubbard model containing two bosons is calculated. When the strength of the single-ion anisotropy is enough large, a isolated single band appears. This isolated single band corresponds to two-boson bound state, which is the simplest quantum breather state. It is shown that the introduction of the next-nearest-neighbor interaction will lead to interesting band structures. In the case of a large number of bosons, by applying the time-dependent Hartree approximation, quantum breather states for the system is constructed. In this case, the effect of the next-nearest-neighbor interaction on quantum breathers is also analyzed.

  19. Particle discrimination of NaI(Tl) scintillator under high-energy neutron field to measure the photon energy spectrum

    Energy Technology Data Exchange (ETDEWEB)

    Kamada, So, E-mail: kamada-s@nmri.go.jp; Takada, Masashi; Suzuki, Toshikazu

    2014-09-11

    Photons are measured separately from neutrons in high-energy neutron fields using a NaI(Tl) scintillator, 7.62 cm in diameter and 7.62 cm in length, combined with a pulse-shape discrimination method. The particle discrimination capability for this scintillator is confirmed using a time-of-flight method. Neutron fields were produced by irradiating Li targets with 40 and 80 MeV proton beams at the cyclotron facility in the National Institute of Radiological Sciences. Figures of merit corresponding to particle discrimination for the scintillator at the two neutron fields are improved with higher neutron energies. Photon energy spectra for energies over 6.5 MeV can be measured using the NaI(Tl) scintillator.

  20. Evolution Operator and Energy Spectrum of a Quasiclassical Particle Interacting with Bosons:. Application to Atom Surface Scattering

    Science.gov (United States)

    Gumhalter, Branko; Kieron, Burke; Langreth, David C.

    We investigate the properties of the interaction of a particle with a boson field describing the response of a solid in the limit in which the interaction matrix elements may be considered as quasiclassical and the particle-boson coupling linear but not necessarily weak. We start by expressing the evolution operator of the system in a convenient form of an exponentiated nested commutator expansion in powers of the interaction potential. From this we are able to estimate under which conditions on the particle motion the contributions of the higher order expansion terms become small, irrespective of the coupling strength. Neglecting such small terms in the exponent of the evolution operator, we can calculate the energy excitation spectrum characteristic of the coupled system or of any of its constituents (particle or boson field). These spectra have the appearance of an exponentiated Born approximation (EBA) which contains and interpolates smoothly between the more frequently used distorted wave Born approximation (DWBA) and the trajectory approximation (TA), thereby covering a wide range of the parameter space for the description of the particle-boson interaction dynamics. The shape of the spectra and their characteristics (the weight of the elastic line or the Debye-Waller factor (DWF), the mean number of excited bosons, and the mean energy transfer in the course of the interaction) are discussed and shown to be very sensitive to the (non)adiabaticity of the switching of the interaction and the magnitude of the particle mass M. In the case of nonadiabatic switching on (as e.g. in photoemission) and linear bosonic density of states, we retrieve in the limit M→∞ the familiar infrared threshold divergences in the spectrum of the system. In the opposite case of adiabatic switching rates typical of scattering, the spectra exhibit a well-defined elastic line and a finite DWF. The case of surface scattering is discussed in more detail for the example of neutral atom

  1. MAXIMA-1: A Measurement of the Cosmic Microwave BackgroundAnisotropy on angular scales of 10' to 5 degrees

    Energy Technology Data Exchange (ETDEWEB)

    Ade, P.; Balbi, A.; Bock, J.; Borrill, J.; Boscaleri, A.; deBernardis, P.; Ferreira, P.G.; Hanany, S.; Hristov, V.V.; Jaffe, A.H.; Lange, A.E.; Lee, A.T.; Mauskopf, P.D.; Netterfield, C.B.; Oh, S.; Pascale, E.; Rabii, B.; Richards, P.L.; Smoot, G.F.; Stompor, R.; Winant,C.D.; Wu, J.H.P.

    2000-10-02

    We present a map and an angular power spectrum of the anisotropy of the cosmic microwave background (CMB) from the first flight of MAXIMA. MAXIMA is a balloon-borne experiment with an array of 16 bolometric photometers operated at 100 mK. MAXIMA observed a 124 deg region of the sky with 10' resolution at frequencies of 150, 240 and 410 GHz. The data were calibrated using in-flight measurements of the CMB dipole anisotropy. A map of the CMB anisotropy was produced from three 150 and one 240 GHz photometer without need for foreground subtractions. Analysis of this CMB map yields a power spectrum for the CMB anisotropy over the range 36 {le} {ell} {le} 785. The spectrum shows a peak with an amplitude of 78 {+-} 6 {mu}K at {ell} {approx_equal} 220 and an amplitude varying between {approx} 40 {mu}K and {approx} 50 {mu}K for 400 {approx}< {ell} {approx}< 785.

  2. Hadron energy spectrum in polarized top-quark decays considering the effects of hadron and bottom quark masses

    International Nuclear Information System (INIS)

    We present the analytical expressions for the next-to-leading order corrections to the partial decay width t(↑) → bW+, followed by b @→ HbX, for nonzero b-quark mass (mb ≠ 0) in the fixed-flavor-number scheme (FFNs). To make the predictions for the energy distribution of outgoing hadrons Hb, as a function of the normalized Hb-energy fraction xH, we apply the general-mass variable-flavor-number scheme (GM-VFNs) in a specific helicity coordinate system where the polarization of top quark is evaluated relative to the b-quark momentum. We also study the effects of gluon fragmentation and finite hadron mass on the hadron energy spectrum so that hadron masses are responsible for the low xH threshold. In order to describe both the b-quark and the gluon hadronizations in top decays we apply realistic and nonperturbative fragmentation functions extracted through a global fit to the e+e- annihilation data from CERN LEP1 and SLAC SLC by relying on their universality and scaling violations. (orig.)

  3. Hadron energy spectrum in polarized top-quark decays considering the effects of hadron and bottom quark masses

    Energy Technology Data Exchange (ETDEWEB)

    Nejad, S.M.M. [Yazd University, Faculty of Physics, P.O. Box 89195-741, Yazd (Iran, Islamic Republic of); Institute for Research in Fundamental Sciences (IPM), School of Particles and Accelerators, P.O.Box 19395-5531, Tehran (Iran, Islamic Republic of); Balali, Mahboobe [Yazd University, Faculty of Physics, P.O. Box 89195-741, Yazd (Iran, Islamic Republic of)

    2016-03-15

    We present the analytical expressions for the next-to-leading order corrections to the partial decay width t(↑) → bW{sup +}, followed by b @→ H{sub b}X, for nonzero b-quark mass (m{sub b} ≠ 0) in the fixed-flavor-number scheme (FFNs). To make the predictions for the energy distribution of outgoing hadrons H{sub b}, as a function of the normalized H{sub b}-energy fraction x{sub H}, we apply the general-mass variable-flavor-number scheme (GM-VFNs) in a specific helicity coordinate system where the polarization of top quark is evaluated relative to the b-quark momentum. We also study the effects of gluon fragmentation and finite hadron mass on the hadron energy spectrum so that hadron masses are responsible for the low x{sub H} threshold. In order to describe both the b-quark and the gluon hadronizations in top decays we apply realistic and nonperturbative fragmentation functions extracted through a global fit to the e{sup +}e{sup -} annihilation data from CERN LEP1 and SLAC SLC by relying on their universality and scaling violations. (orig.)

  4. GRAPES-3-A high-density air shower array for studies on the structure in the cosmic-ray energy spectrum near the knee

    International Nuclear Information System (INIS)

    The change in the spectral index from about -2.7 to -3.1 at ∼3x1015eV in the all-particle energy spectrum of primary cosmic rays is very significant for learning about the nature of cosmic sources of ultra-high energy particles and their acceleration and propagation in the galactic disk. Any observation of a fine structure in the spectrum would be important for improving our understanding of these physical processes. The GRAPES-3 air shower array has been designed to achieve higher precision in determination of various shower parameters to enable observation of any fine structure in the energy spectrum, if it exists. The details of the shower detectors, shower trigger and the data acquisition system are presented here along with estimates of trigger efficiencies from Monte Carlo simulations for primary photons (γ-rays) and several nuclei

  5. Energy spectrum of layered semiconductors in a magnetic field parallel to the layers: Voigt geometry

    Science.gov (United States)

    Yoo, K. H.; Ram-Mohan, L. R.

    2010-11-01

    The electronic band structure of zinc-blende layered semiconductor heterostructures is investigated theoretically in the presence of an in-plane magnetic field, a configuration we label as the Voigt geometry. We use a Lagrangian formulation for modeling the band structure in the individual layers within the kṡP model. This approach has been shown by us to provide the correct ordering of the derivatives appearing in the multiband description of Schrödinger’s equations for the envelope functions through the application of the principle of stationary action. Finite element modeling of the action integral provides a natural and efficient approach to the inclusion of in-plane magnetic fields in the energy-level analysis. Calculations for quantum wells and superlattices are presented, and the complex energy-level structure obtained for the layered structures.

  6. Two-Electron Energy Spectrum in a Parabolic Quantum Dot Under a Magnetic Field

    Institute of Scientific and Technical Information of China (English)

    XIE Wen-Fang

    2003-01-01

    Two interacting electrons in a harmonic oscillator potential under the influence of a perpendicular homo-geneous magnetic field are considered. The energies of two-electron quantum dots with the electron-LO-phonon couplingas a function of magnetic field are calculated. Calculations are made by using the method of few-body physics withinthe effective-mass approximation. Our results show that the electron-LO-phonon coupling effect is very important insemiconductor quantum dots.

  7. Low-energy constants and condensates from the V-A spectrum

    CERN Document Server

    Boito, D; Jamin, M; Maltman, K; Peris, S

    2013-01-01

    We present an analysis of the isospin-one V-A correlator based on our successful simultaneous description of the OPAL V and A non-strange tau spectral data. We discuss the values obtained for the Chiral Perturbation Theory low-energy constants L_10 and C_87 as well as the dimension-six and eight condensates and compare them with those in the literature.

  8. The excitation energy spectrum for a system with electron pairs tunneling in a two-leg ladder has a doping depended gap

    CERN Document Server

    Voroshilov, Valentin

    2016-01-01

    A new model with a new Hamiltonian and a new canonical transformation is offered as the means for studying properties of a system of strongly correlated electrons. Consideration of the simplest possible situation, namely a system on non-interacting electrons in a two-leg ladder, leads to an expression for the excitation energy spectrum with no energy gap at the half-filling and with an energy gap away from the half filling.

  9. Theoretical analysis of a biased photonic crystal fiber infiltrated with a negative dielectric anisotropy liquid crystal

    DEFF Research Database (Denmark)

    Weirich, Johannes; Wei, Lei; Lægsgaard, Jesper;

    2009-01-01

    We simulate the PBG mode of a biased Photonic Crystal Fiber (PCF) infiltrated with a Liquid Crystal (LC) with negative dielectric anisotropy. We analyse the voltage induced change of the transmission spectrum, dispersion and losses and compare them to the experimental values.......We simulate the PBG mode of a biased Photonic Crystal Fiber (PCF) infiltrated with a Liquid Crystal (LC) with negative dielectric anisotropy. We analyse the voltage induced change of the transmission spectrum, dispersion and losses and compare them to the experimental values....

  10. Cosmic Strings as the Source of Small-Scale Microwave Background Anisotropy

    CERN Document Server

    Pogosian, Levon; Wasserman, Ira; Wyman, Mark

    2008-01-01

    Cosmic string networks generate cosmological perturbations actively throughout the history of the universe. Thus, the string sourced anisotropy of the cosmic microwave background is not affected by Silk damping as much as the anisotropy seeded by inflation. The spectrum of perturbations generated by strings does not match the observed CMB spectrum on large angular scales (l2000) will dominate over that created by the primary inflationary perturbations. This range of angular scales in the CMB is presently being measured by a number of experiments; their results will test this prediction of cosmic string networks soon.

  11. Commensurate and incommensurate states of a spin density wave in a quasi-two-dimensional system with an anisotropic energy spectrum in an external magnetic field of arbitrary direction relative to magnetization

    Energy Technology Data Exchange (ETDEWEB)

    Palistrant, M. E., E-mail: mepalistrant@yandex.com; Ursu, V. A. [Academy of Sciences of Moldova, Institute of Applied Physics (Moldova, Republic of)

    2013-04-15

    A theory of thermodynamic properties of a spin density wave (SDW) in a quasi-two-dimensional system (with a preset impurity concentration x) is constructed. We choose an anisotropic dispersion relation for the electron energy and assume that external magnetic field H has an arbitrary direction relative to magnetic moment M{sub Q}. The system of equations defining order parameters M{sub Q}{sup z}, M{sub Q}{sup {sigma}}, M{sub z}, and M{sup {sigma}} is constructed and transformed with allowance for the Umklapp processes. Special cases when H Double-Vertical-Line M{sub Q} and H Up-Tack M{sub Q} (H{sub Z}H{sup {sigma}} = 0) are considered in detail as well as cases of weak fields H of arbitrary direction. The condition for the transition of the system to the commensurate and incommensurate states of the SDW is analyzed. The concentration dependence of magnetic transition temperature T{sub M} is calculated, and the components of the order parameter for the incommensurate phase are determined. The phase diagram (T,{approx}x) is constructed. The effect of the magnetic field on magnetic transition temperature T{sub M} is analyzed for H{sub Z}H{sup {sigma}} = 0, and longitudinal magnetic susceptibility {chi} Double-Vertical-Line is calculated; this quantity demonstrates the temperature dependence corresponding to a system with a gap for x < x{sub c} and to a gapless state for x > x{sub c}. In the immediate vicinity of the critical impurity concentration (x {approx} x{sub c}), the temperature dependence of the magnetic susceptibility acquires a local maximum. The effect of anisotropy of the electron energy spectrum on the investigated physical quantities is also analyzed.

  12. A New Nonrelativistic Atomic Energy Spectrum of Energy Dependent Potential for Heavy Quarkouniom in Noncommutative Spaces and Phases Symmetries

    Directory of Open Access Journals (Sweden)

    Abdelmadjid Maireche

    2016-06-01

    Full Text Available The main objective of this search work is to study a three dimensional space-phase modified Schrödinger equation with energy dependent potential plus three terms: , and is carried out. Together with the Boopp’s shift method and standard perturbation theory the new energy spectra shown to be dependent with new atomic quantum in the non-commutative three dimensional real spaces and phases symmetries (NC-3D: RSP and we have also constructed the corresponding deformed noncommutative Hamiltonian for studied potential.

  13. Spectrum sensitivity, energy yield, and revenue prediction of PV and CPV modules

    Science.gov (United States)

    Kinsey, Geoffrey S.

    2015-09-01

    Impact on module performance of spectral irradiance variation has been determined for III-V multijunctions compared against the four most common flat-plate module types (cadmium telluride, multicrystalline silicon, copper indium gallium selenide, and monocrystalline silicon. Hour-by-hour representative spectra were generated using atmospheric variables for Albuquerque, New Mexico, USA. Convolution with published values for external quantum efficiency gave the predicted current output. When combined with specifications of commercial PV modules, energy yield and revenue were predicted. This approach provides a means for optimizing PV module design based on various site-specific temporal variables.

  14. Target thickness dependence of the Be(p,xn neutron energy spectrum

    Directory of Open Access Journals (Sweden)

    Rakopoulos V.

    2014-03-01

    Full Text Available We report on the current status of the analysis of an experiment performed at The Svedberg Laboratory, with the aim of investigating the produced neutron field by Be(p,xn converters of three different thicknesses with a 30 MeV proton beam. The neutron energy spectra were measured with the Time of Flight technique using a BC-501 liquid scintillator with good n-γ Pulse Shape Discrimination properties, while the detected events were recorded simultaneously by two Data AcQuisition systems. In this paper, we present the experimental setup, the analysis technique and some preliminary results.

  15. Transition from geostrophic turbulence to inertia-gravity waves in the atmospheric energy spectrum.

    Science.gov (United States)

    Callies, Jörn; Ferrari, Raffaele; Bühler, Oliver

    2014-12-01

    Midlatitude fluctuations of the atmospheric winds on scales of thousands of kilometers, the most energetic of such fluctuations, are strongly constrained by the Earth's rotation and the atmosphere's stratification. As a result of these constraints, the flow is quasi-2D and energy is trapped at large scales—nonlinear turbulent interactions transfer energy to larger scales, but not to smaller scales. Aircraft observations of wind and temperature near the tropopause indicate that fluctuations at horizontal scales smaller than about 500 km are more energetic than expected from these quasi-2D dynamics. We present an analysis of the observations that indicates that these smaller-scale motions are due to approximately linear inertia-gravity waves, contrary to recent claims that these scales are strongly turbulent. Specifically, the aircraft velocity and temperature measurements are separated into two components: one due to the quasi-2D dynamics and one due to linear inertia-gravity waves. Quasi-2D dynamics dominate at scales larger than 500 km; inertia-gravity waves dominate at scales smaller than 500 km. PMID:25404349

  16. Energy Efficiency and SINR Maximization Beamformers for Spectrum Sharing With Sensing Information

    KAUST Repository

    Alabbasi, Abdulrahman

    2014-09-01

    In this paper, we consider a cognitive radio multi-input-multi-output environment, in which we adapt our beamformer to maximize both energy efficiency (EE) and signal-to-interference-plus-noise ratio (SINR) metrics. Our design considers an underlaying communication using adaptive beamforming schemes combined with sensing information to achieve optimal energy-efficient systems. The proposed schemes maximize EE and SINR metrics subject to cognitive radio and quality-of-service constraints. The analysis of the proposed schemes is classified into two categories based on knowledge of the secondary-transmitter-to-primary-receiver channel. Since the optimizations of EE and SINR problems are not convex problems, we transform them into a standard semidefinite programming (SDP) form to guarantee that the optimal solutions are global. An analytical solution is provided for one scheme, while the second scheme is left in a standard SDP form. Selected numerical results are used to quantify the impact of the sensing information on the proposed schemes compared to the benchmark ones.

  17. Capacity Development and Strengthening for Energy Policy formulation and implementation of Sustainable Energy Projects in Indonesia CASINDO. Deliverable No. 13. Integration of Renewable Energy Technologies in the national curriculum SPECTRUM

    Energy Technology Data Exchange (ETDEWEB)

    Kamphuis, E. [ETC Nederland, Leusden (Netherlands); Permana, I. [Technical Education Development Centre TEDC, Bandung (Indonesia)

    2011-11-15

    The overall objective of the CASINDO programme is to establish a self-sustaining and self-developing structure at both the national and regional level to build and strengthen human capacity to enable the provinces of North Sumatra, Yogyakarta, Central Java, West Nusa Tenggara and Papua to formulate sound policies for renewable energy and energy efficiency and to develop and implement sustainable energy projects. This report focuses on the achievements for settling a national curriculum for Renewable Energy Technologies (RET) within the framework of national programme SPECTRUM, which includes all curricula of the medium technical schools in Indonesia.

  18. Study of ultra-energetic cosmic rays at the Pierre Auger Observatory from particle detection to anisotropy measurement; Etude des rayons cosmiques ultra-energetiques avec l'Observatoire de Pierre Auger: de l'acceptance du detecteur a la nature des particules primaires et aux mesures d'anisotropies

    Energy Technology Data Exchange (ETDEWEB)

    Aublin, J

    2006-09-15

    The Pierre Auger Observatory, still under construction in Argentina, is designed to study the cosmic rays with energies above a few EeV. The experiment combines two complementary techniques: the fluorescence light detection and the sampling of the shower with an array of detectors at ground, covering a surface of 3000 square kilometers. The calculation of the acceptance of the detector, which is of utmost importance to establish the energy spectrum, has been achieved. The method of computation of the acceptance is simple and reliable. The detection efficiency depends on the nature of primary cosmic rays, allowing to study the cosmic rays composition with the surface detector. The calculation of the cosmic rays energy spectrum has been performed, using different methods to estimate the energy of the events. A cross calibration between the fluorescence and the surface detector provides an estimation of the energy almost independent of hadronic interaction models. The study of large scale anisotropies in the cosmic rays angular distribution provides useful informations about the cosmic rays sources and the conditions of propagation. A new analysis method is presented, allowing to estimate the parameters of an underlying dipolar and quadrupolar anisotropy in the data. The method is applied to a preliminary Auger data set. (author)

  19. Vorticity and Magnetic Field Generation from Initial Anisotropy in Ultrarelativistic Gamma-Ray Burst Blastwaves

    CERN Document Server

    Milosavljevic, Milos; Zhang, Fan

    2007-01-01

    Because conical segments of quasispherical ultrarelativistic blastwaves are causally disconnected on angular scales larger than the blastwave inverse Lorentz factor, astrophysical blastwaves can sustain initial anisotropy, imprinted by the process that drives the explosion, while they remain relativistic. We show that initial angular energy fluctuations in ultrarelativistic blastwaves imply a production of vorticity in the blastwave, and calculate the vortical energy production rate. In gamma-ray burst (GRB) afterglows, the number of vortical eddy turnovers as the shocked fluid crosses the blastwave shell is about unity for marginally nonlinear anisotropy. Thus the anisotropy must be nonlinear to explain the magnetic energy density inferred in measured GRB spectra.

  20. High-resolution Rotational Spectrum, Dunham Coefficients, and Potential Energy Function of NaCl

    Science.gov (United States)

    Cabezas, C.; Cernicharo, J.; Quintana-Lacaci, G.; Peña, I.; Agundez, M.; Velilla Prieto, L.; Castro-Carrizo, A.; Zuñiga, J.; Bastida, A.; Alonso, J. L.; Requena, A.

    2016-07-01

    We report laboratory spectroscopy for the first time of the J = 1–0 and J = 2–1 lines of Na35Cl and Na37Cl in several vibrational states. The hyperfine structure has been resolved in both transitions for all vibrational levels, which permit us to predict with high accuracy the hyperfine splitting of the rotational transitions of the two isotopologues at higher frequencies. The new data have been merged with all previous works at microwave, millimeter, and infrared wavelengths and fitted to a series of mass-independent Dunham parameters and to a potential energy function. The obtained parameters have been used to compute a new dipole moment function, from which the dipole moment for infrared transitions up to Δv = 8 has been derived. Frequency and intensity predictions are provided for all rovibrational transitions up to J = 150 and v = 8, from which the ALMA data of evolved stars can be modeled and interpreted.

  1. Diffractive charmonium spectrum in high energy collisions in the basis light-front quantization approach

    CERN Document Server

    Chen, Guangyao; Maris, Pieter; Tuchin, Kirill; Vary, James P

    2016-01-01

    Using the charmonium light-front wavefunctions obtained by diagonalizing an effective Hamiltonian with the one-gluon exchange interaction and a confining potential inspired by light-front holography in the basis light-front quantization formalism, we compute production of charmonium states in diffractive deep inelastic scattering and ultra-peripheral heavy ion collisions within the dipole picture. Our method allows us to predict yields of all excited charmonium and bottomonium states below the open flavor thresholds in high-energy deep inelastic scattering, proton-nucleus and ultra-peripheral heavy ion collisions. The obtained charmonium cross section is in reasonable agreement with experimental data at HERA, RHIC and LHC. We observe that the cross-section ratio $\\sigma_{\\Psi(2s)}/\\sigma_{J/\\Psi}$ reveals significant independence of model parameters.

  2. High-Resolution Rotational Spectrum, Dunham Coefficients, and Potential Energy Function of NaCl

    Science.gov (United States)

    Cabezas, C.; Cernicharo, J.; Quintana-Lacaci, G.; Peña, I.; Agundez, M.; Prieto, L. Velilla; Castro-Carrizo, A.; Zuñiga, J.; Bastida, A.; Alonso, J. L.; Requena, A.

    2016-01-01

    We report laboratory spectroscopy for the first time of the J = 1–0 and J = 2–1 lines of Na35Cl and Na37Cl in several vibrational states. The hyperfine structure has been resolved in both transitions for all vibrational levels, which permit us to predict with high accuracy the hyperfine splitting of the rotational transitions of the two isotopologues at higher frequencies. The new data have been merged with all previous works at microwave, millimeter, and infrared wavelengths and fitted to a series of mass-independent Dunham parameters and to a potential energy function. The obtained parameters have been used to compute a new dipole moment function, from which the dipole moment for infrared transitions up to Δv = 8 has been derived. Frequency and intensity predictions are provided for all rovibrational transitions up to J = 150 and v = 8, from which the ALMA data of evolved stars can be modeled and interpreted.

  3. Bio-hybrid integrated system for wide-spectrum solar energy harvesting

    Science.gov (United States)

    Martin, Kathleen; Erdman, Matthew; Quintana, Hope; Shelnutt, John; Nogan, John; Swartzentruber, B.; Martinez, Julio; Lavrova, Olga; Busani, Tito

    2014-03-01

    An integrated hybrid photovoltaic-thermoelectric system has been developed using multiple layers of organic photosensitizers on inorganic semiconductors in order to efficiently convert UV-visible and IR energy into electricity. The hot anode of n-type ZnO nanowires was fabricated using a thermal process on pre-seeded layer and results to be crystalline with a transmittance up to 92 % and a bandgap of 3.32 eV. The visible-UV light-active organic layer was deposited between the anode and cathode at room temperature using a layer-by-layer deposition onto ITO and ZnO and Bi2Te3 nanowires from aqueous solution. The organic layer, a cooperative binary ionic (CBI) solid is composed of oppositely charged porphyrin metal (Zn(II) and Sn(IV)(OH-)2) derivatives that are separately water soluble, but when combined form a virtually insoluble solid. The electron donor/acceptor properties (energy levels, band gaps) of the solid can be controlled by the choice of metals and the nature of the peripheral substituent groups of the porphyrin ring. The highly thermoelectric structure, which acts as a cold cathode, is composed of p-type Bi2Te3 nanowires with a thermoelectric efficiency (ZT) between ~0.7 to 1, values that are twice that expected for bulk Bi2Te3. Efficiency of the integrated device, was found to be 35 at 0.2 suns illumination and thermoelectric properties are enhanced by the charge transfer between the CBI and the Bi2Te3 is presented in terms of photo- and thermogenerated current and advantages of the low cost fabrication process is discussed.

  4. Sensitivity of YAC to measure the light-component spectrum of primary cosmic rays at the "knee" energies

    CERN Document Server

    Zhai, L M; Chen, D; Shibata, M; Katayose, Y; Zhang, Ying; Liu, J S; Chen, Xu; Hu, X B; Lin, Y H

    2016-01-01

    A new air-shower core-detector array (YAC : Yangbajing Air-shower Core-detector array) has been developed to measure the primary cosmic-ray composition at the "knee" energies in Tibet, China, focusing mainly on the light components. The prototype experiment (YAC-I) consisting of 16 detectors has been constructed and operated at Yangbajing (4300 m a.s.l.) in Tibet since May 2009. YAC-I is installed in the Tibet-III AS array and operates together. In this paper, we performed a Monte Carlo simulation to check the sensitivity of YAC-I+Tibet-III array to the cosmic-ray light component of cosmic rays around the knee energies, taking account of the observation conditions of actual YAC-I+Tibet-III array. The selection of light component from others was made by use of an artificial neural network (ANN). The simulation shows that the light-component spectrum estimated by our methods can well reproduce the input ones within 10\\% error, and there will be about 30\\% systematic errors mostly induced by the primary and inte...

  5. Measurement of the inclusive $B\\to X_{s+d} \\gamma$ branching fraction, photon energy spectrum and HQE parameters

    CERN Document Server

    ,

    2016-01-01

    We report a measurement of the inclusive $B\\to X_{s+d} \\gamma$ and $B\\to X_{s} \\gamma$ branching fractions using a data set of $(772 \\pm 11)\\times 10^6$ $B\\bar{B}$ pairs collected at the $\\Upsilon(4S)$ resonance with the Belle detector at the KEKB asymmetric-energy $e^+e^-$ collider. Results are presented for photon energy thresholds between 1.7 to 2.0 GeV. For the 1.8 GeV threshold we find $\\mathcal{B}_{s\\gamma} = (3.01 \\pm 0.10~\\text{(stat)} \\pm 0.18~\\text{(syst)} \\pm 0.08~\\text{(model)})\\times 10^{-4}$. The Heavy Quark Expansion parameters that best fit the spectrum in the shape-function scheme are $m_{b} = (4.626 \\pm 0.028) \\text{GeV}$ and $ \\mu_{\\pi}^{2} = (0.301\\pm 0.063) \\text{GeV}^2$.

  6. A Method to Assign Spread Codes Based on Passive RFID Communication for Energy Harvesting Wireless Sensors Using Spread Spectrum Transmission

    Directory of Open Access Journals (Sweden)

    Ken Takahashi

    2015-08-01

    Full Text Available Considerable research has been conducted on systems that collect real-world information by using numerous energy harvesting wireless sensors. The sensors need to be tiny, cheap, and consume ultra-low energy. However, such sensors have some functional limits, including being restricted to wireless communication transmission. Therefore, when more than one sensor simultaneously transmits information in these systems, the receiver may not be able to demodulate if the sensors cannot accommodate multiple access. To solve this problem, a number of proposals have been made based on spread spectrum technologies for resistance to interference. In this paper, we point out some problems regarding the application of such sensors, and explain the assumption of spread codes assignment based on passive radio frequency identification (RFID communication. During the spread codes assignment, the system cannot work. Hence, efficient assignment method is more appropriate. We consider two assignment methods and assessed them in terms of total assignment time through an experiment. The results show the total assignment time in case of Electronic Product Code (EPC Global Class-1 Generation-2 which is an international standard for wireless protocols and the relationship between the ratio of the time taken by the read/write command and the ratio of total assignment time by the two methods. This implies that more efficient methods are obtained by considering the time ratio of read/write command.

  7. Angular anisotropy of the fusion-fission and quasifission fragments

    CERN Document Server

    Nasirov, A K; Utamuratov, R K; Fazio, G; Giardina, G; Hanappe, F; Mandaglio, G; Manganaro, M; Scheid, W

    2007-01-01

    The anisotropy in the angular distribution of the fusion-fission and quasifission fragments for the $^{16}$O+$^{238}$U, $^{19}$F+$^{208}$Pb and $^{32}$S+$^{208}$Pb reactions is studied by analyzing the angular momentum distributions of the dinuclear system and compound nucleus which are formed after capture and complete fusion, respectively. The orientation angles of axial symmetry axes of colliding nuclei to the beam direction are taken into account for the calculation of the variance of the projection of the total spin onto the fission axis. It is shown that the deviation of the experimental angular anisotropy from the statistical model picture is connected with the contribution of the quasifission fragments which is dominant in the $^{32}$S+$^{208}$Pb reaction. Enhancement of anisotropy at low energies in the $^{16}$O+$^{238}$U reaction is connected with quasifission of the dinuclear system having low temperature and effective moment of inertia.

  8. Polarization of thermal bremsstrahlung emission due to electron pressure anisotropy

    CERN Document Server

    Komarov, S; Churazov, E; Schekochihin, A

    2016-01-01

    Astrophysical plasmas are typically magnetized, with the Larmor radii of the charged particles many orders of magnitude smaller than their collisional mean free paths. The fundamental properties of such plasmas, e.g., conduction and viscosity, may depend on the instabilities driven by the anisotropy of the particle distribution functions and operating at scales comparable to the Larmor scales. We discuss a possibility that the pressure anisotropy of thermal electrons could produce polarization of thermal bremsstrahlung emission. In particular, we consider coherent large-scale motions in galaxy clusters to estimate the level of anisotropy driven by stretching of the magnetic-field lines by plasma flow and by heat fluxes associated with thermal gradients. Our estimate of the degree of polarization is $\\sim 0.1 \\%$ at energies $\\gtrsim kT$. While this value is too low for the forthcoming generation of X-ray polarimeters, it is potentially an important proxy for the processes taking place at extremely small scale...

  9. [BIOLOGICAL EFFECTIVENESS OF FISSION SPECTRUM NEUTRONS AND PROTONS WITH ENERGIES OF 60-126 MEV DURING ACUTE AND PROLONGED IRRADIATION].

    Science.gov (United States)

    Shafirkin, A V

    2015-01-01

    Neutrons of the fission spectrum are characterized by relatively high values of linear energy transfer (LET). Data about their effects on biological objects are used to evaluate the risk of delayed effects of accelerated ions within the same LET range that serve as an experimental model of the nuclei component of galactic cosmic rays (GCR). Additionally, risks of delayed consequences to cosmonaut's health and average lifetime from certain GCR fluxes and secondary neutrons can be also prognosticated. The article deals with comparative analysis of the literature on reduction of average lifespan (ALS) of animals exposed to neutron reactor spectrum, 60-126 MeV protons, and X- and γ-rays in a broad range of radiation intensity and duration. It was shown that a minimal lifespan reduction by 5% occurs due to a brief exposure to neutrons with the absorbed dose of 5 cGy, whereas same lifespan reduction due to hard X- and γ-radiation occurs after absorption of a minimal dose of 100 cGy. Therefore, according to the estimated minimal ALS reduction in mice, neutron effectiveness is 20-fold higher. Biological effectiveness of protons as regards ALS reduction is virtually equal to that of standard types of radiation. Exposure to X- and γ-radiation with decreasing daily doses, and increasing number of fractions and duration gives rise to an apparent trend toward a less dramatic ALS reduction in mice; on the contrary, exposure to neutrons of varying duration had no effect on threshold doses for the specified ALS reductions. Factors of relative biological effectiveness of neutrons reached 40. PMID:26934784

  10. EPHIN anisotropy measurement capability

    Science.gov (United States)

    Banjac, S.; Gómez-Herrero, R.; Heber, B.; Kühl, P.; Terasa, C.

    2015-08-01

    The EPHIN instrument (Electron Proton Helium INstrument) forms a part of the COSTEP experiment (COmprehensive SupraThermal and Energetic Particle Analyzer) within the CEPAC collaboration on board of the SOHO spacecraft (SOlar and Heliospheric Observatory). The EPHIN sensor is a stack of six solid-state detectors surrounded by an anticoincidence. It measures energy spectra of electrons in the range 250 keV to > 8.7 MeV, and hydrogen and helium isotopes in the range 4 MeV/nuc to > 53 MeV/nuc. In order to improve the isotopic resolution, the first two detectors have been segmented: 5 sectors form a ring enclosing a central segment. This does not only allow to correct the energy-losses for particles with different path-lengths in the detectors, but allows also an estimation of the arrival direction with respect to the sensor axis. For that purpose we developed a method that allows for inferring the angle of incidence and angular distribution for ions. Here we describe the method and apply it to the November, 3, 2011 event. Due to the lack of magnetic field measurements and the restricted view cone of 83°, it is not possible to derive a real pitch angle distribution during this event. However, we can show that the particle distribution is anisotropic for several hours with a symmetry axis that deviates by about 20° from the sensor axis.

  11. Monte Carlo simulations of medium-scale CMB anisotropy

    CERN Document Server

    Kogut, A J

    1996-01-01

    Recent detections of cosmic microwave background (CMB) anisotropy at half-degree angular scales show considerable scatter in the reported amplitude even at similar angular resolution. We use Monte Carlo techniques to simulate the current set of medium-scale CMB observations, including all relevant aspects of sky coverage and measurement technique. The scatter in the reported amplitudes is well within the range expected for the standard cold dark matter (CDM) cosmological model, and results primarily from the restricted sky coverage of each experiment. Within the context of standard CDM current observations of CMB anisotropy support the detection of a ``Doppler peak'' in the CMB power spectrum consistent with baryon density 0.01 < Omega_b < 0.13 (95% confidence) for Hubble constant H_0 = 50 km/s/Mpc. The uncertainties are approximately evenly divided between instrument noise and cosmic variance arising from the limited sky coverage.

  12. Energy Spectrum of YAG:Cr3+ and Thermal Shifts of Its R Lines

    Institute of Scientific and Technical Information of China (English)

    MADong-Ping; CHENJu-Rong

    2005-01-01

    Traditional ligand-field theory has to be improved by taking into account both “pure electronic” contribution and electron-phonon interaction one (including lattice-vibrational relaxation energy). By means of improved ligand-field theory, R1, R2, R'3 R'2 a, 2, and R1 lines, U band, ground-state zero-field-splitting (GSZFS) and ground-state g factors as well as thermal shifts of R1 line and R2 line of YAG:Cr3+ have been calculated. The results are in very good agreement with the experimental data. In contrast with ruby, the octahedron of ligand oxygen ions surrounding the central Cr3+ ion in YAG:Cr3+ is compressed along the [111] direction. Thus, for YAG:Cr3+ and ruby, the splitting of t23 4 A2 (or t23 2 E) has opposite order, and the trigonal-field parameters of the two crystals have opposite signs. In thermal shifts of R1 and R2 lines of YAG:Cr3+, the temperature-dependent contributions due to EPI are dominant.

  13. Low-energy spectrum of iron-sulfur clusters directly from many-particle quantum mechanics

    CERN Document Server

    Sharma, Sandeep; Neese, Frank; Chan, Garnet Kin-Lic

    2014-01-01

    FeS clusters are a universal biological motif. They carry out electron transfer, redox chemistry, and even oxygen sensing, in diverse processes including nitrogen fixation, respiration, and photosynthesis. The low-lying electronic states are key to their remarkable reactivity, but cannot be directly observed. Here we present the first ever quantum calculation of the electronic levels of [2Fe-2S] and [4Fe-4S] clusters free from any model assumptions. Our results highlight limitations of long-standing models of their electronic structure. In particular, we demonstrate that the widely used Heisenberg-Double-Exchange model underestimates the number of states by 1-2 orders of magnitude, which can conclusively be traced to the absence of Fe d$\\rightarrow$d excitations, thought to be important in these clusters. Further, the electronic energy levels of even the same spin are dense on the scale of vibrational fluctuations, and this provides a natural explanation for the ubiquity of these clusters in nature for cataly...

  14. A two-fluid approximation for calculating the cosmic microwave background anisotropies

    Science.gov (United States)

    Seljak, Uros

    1994-01-01

    We present a simplified treatment for calculating the cosmic microwave background anisotropy power spectrum in adiabatic models. It consists of solving for the evolution of a two-fluid model until the epoch of recombination and then integrating over the sources to obtain the cosmic microwave background (CMB) anisotropy power spectrum. The approximation is useful both for a physical understanding of CMB anisotropies as well as for a quantitative analysis of cosmological models. Comparison with exact calculations shows that the accuracy is typically 10%-20% over a large range of angles and cosmological models, including those with curvature and cosmological constant. Using this approximation we investigate the dependence of the CMB anisotropy on the cosmological parameters. We identify six dimensionless parameters that uniquely determine the anisotropy power spectrum within our approximation. CMB experiments on different angular scales could in principle provide information on all these parameters. In particular, mapping of the Doppler peaks would allow an independent determination of baryon mass density, matter mass density, and the Hubble constant.

  15. Search for anisotropies in cosmic-ray positrons detected by the PAMELA experiment

    CERN Document Server

    Adriani, O; Bazilevskaya, G A; Bellotti, R; Boezio, M; Bogomolov, E A; Bongi, M; Bonvicini, V; Bottai, S; Bruno, A; Cafagna, F; Campana, D; Carlson, P; Casolino, M; Castellini, G; De Donato, C; De Santis, C; De Simone, N; Di Felice, V; Formato, V; Galper, A M; Giaccari, U; Karelin, A V; Koldashov, S V; Koldobskiy, S; Krutkov, S Y; Kvashnin, A N; Leonov, A; Malakhov, V; Marcelli, L; Martucci, M; Mayorov, A G; Menn, W; Mergè, M; Mikhailov, V V; Mocchiutti, E; Monaco, A; Mori, N; Munini, R; Osteria, G; Palma, F; Panico, B; Papini, P; Pearce, M; Picozza, P; Ricci, M; Ricciarini, S B; Sarkar, R; Scotti, V; Simon, M; Sparvoli, R; Spillantini, P; Stozhkov, Y I; Vacchi, A; Vannuccini, E; Vasilyev, G I; Voronov, S A; Yurkin, Y T; Zampa, G; Zampa, N

    2015-01-01

    The PAMELA detector was launched on board of the Russian Resurs-DK1 satellite on June 15, 2006. Data collected during the first four years have been used to search for large-scale anisotropies in the arrival directions of cosmic-ray positrons. The PAMELA experiment allows for a full sky investigation, with sensitivity to global anisotropies in any angular window of the celestial sphere. Data samples of positrons in the rigidity range 10 GV $\\leq$ R $\\leq$ 200 GV were analyzed. This article discusses the method and the results of the search for possible local sources through analysis of anisotropy in positron data compared to the proton background. The resulting distributions of arrival directions are found to be isotropic. Starting from the angular power spectrum, a dipole anisotropy upper limit \\delta = 0.076 at 95% C.L. is determined. Additional search is carried out around the Sun. No evidence of an excess correlated with that direction was found.

  16. Magnetoresistance Anisotropy in WTe2

    Science.gov (United States)

    Thoutam, Laxman Raju; Wang, Yonglei; Xiao, Zhili; Das, Saptarshi; Luican Mayer, Adina; Divan, Ralu; Crabtree, George W.; Kwok, Wai Kwong

    We report the angle dependence of the magnetoresistance in WTe2. Being a layered material, WTe2 is considered to be electronically two-dimensional (2D). Our results demonstrate that it is in fact 3D with an anisotropy of effective mass as small as 2. We measured the magnetic field dependence of the sample resistance R(H) at various angles between the applied magnetic field with respect to the c-axis of the crystal and found that they can be scaled based on the mass anisotropy, which changes from ~2 to ~5 with decreasing temperature in the Fermi liquid state. We will also discuss the origin of the turn-on temperature behavior in this material.

  17. Structural Anisotropy in Polar Fluids Subjected to Periodic Boundary Conditions

    Science.gov (United States)

    2011-01-01

    A heuristic model based on dielectric continuum theory for the long-range solvation free energy of a dipolar system possessing periodic boundary conditions (PBCs) is presented. The predictions of the model are compared to simulation results for Stockmayer fluids simulated using three different cell geometries. The boundary effects induced by the PBCs are shown to lead to anisotropies in the apparent dielectric constant and the long-range solvation free energy of as much as 50%. However, the sum of all of the anisotropic energy contributions yields a value that is very close to the isotropic one derived from dielectric continuum theory, leading to a total system energy close to the dielectric value. It is finally shown that the leading-order contribution to the energetic and structural anisotropy is significantly smaller in the noncubic simulation cell geometries compared to when using a cubic simulation cell. PMID:22303290

  18. Stress-anneal-induced magnetic anisotropy in highly textured Fe-Ga and Fe-Al magnetostrictive strips for bending-mode vibrational energy harvesters

    Science.gov (United States)

    Park, Jung Jin; Na, Suok-Min; Raghunath, Ganesh; Flatau, Alison B.

    2016-05-01

    Magnetostrictive Fe-Ga and Fe-Al alloys are promising materials for use in bending-mode vibrational energy harvesters. For this study, 50.8 mm × 5.0 mm × 0.5 mm strips of Fe-Ga and Fe-Al were cut from 0.50-mm thick rolled sheet. An atmospheric anneal was used to develop a Goss texture through an abnormal grain growth process. The anneal lead to large (011) grains that covered over 90% of sample surface area. The resulting highly-textured Fe-Ga and Fe-Al strips exhibited saturation magnetostriction values (λsat = λ∥ - λ⊥) of ˜280 ppm and ˜130 ppm, respectively. To maximize 90° rotation of magnetic moments during bending of the strips, we employed compressive stress annealing (SA). Samples were heated to 500°C, and a 100-150 MPa compressive stress was applied while at 500°C for 30 minutes and while being cooled. The effectiveness of the SA on magnetic moment rotation was inferred by comparing post-SA magnetostriction with the maximum possible yield of rotated magnetic moments, which is achieved when λ∥ = λsat and λ⊥ = 0. The uniformity of the SA along the sample length and the impact of the SA on sensing/energy harvesting performance were then assessed by comparing pre- and post-SA bending-stress-induced changes in magnetization at five different locations along the samples. The SA process with a 150 MPa compressive load improved Fe-Ga actuation along the sample length from 170 to 225 ppm (from ˜60% to within ˜80% of λsat). The corresponding sensing/energy harvesting performance improved by as much as a factor of eight in the best sample, however the improvement was not at all uniform along the sample length. The SA process with a 100 MPa compressive load improved Fe-Al actuation along the sample length from 60 to 73 ppm (from ˜46% to ˜56% of λsat, indicating only a marginally effective SA and suggesting the need for modification of the SA protocol. In spite of this, the SA was effective at improving the sensing/energy harvesting

  19. Stress-anneal-induced magnetic anisotropy in highly textured Fe-Ga and Fe-Al magnetostrictive strips for bending-mode vibrational energy harvesters

    Directory of Open Access Journals (Sweden)

    Jung Jin Park

    2016-05-01

    Full Text Available Magnetostrictive Fe-Ga and Fe-Al alloys are promising materials for use in bending-mode vibrational energy harvesters. For this study, 50.8 mm × 5.0 mm × 0.5 mm strips of Fe-Ga and Fe-Al were cut from 0.50-mm thick rolled sheet. An atmospheric anneal was used to develop a Goss texture through an abnormal grain growth process. The anneal lead to large (011 grains that covered over 90% of sample surface area. The resulting highly-textured Fe-Ga and Fe-Al strips exhibited saturation magnetostriction values (λsat =  λ∥ − λ⊥ of ∼280 ppm and ∼130 ppm, respectively. To maximize 90° rotation of magnetic moments during bending of the strips, we employed compressive stress annealing (SA. Samples were heated to 500°C, and a 100-150 MPa compressive stress was applied while at 500°C for 30 minutes and while being cooled. The effectiveness of the SA on magnetic moment rotation was inferred by comparing post-SA magnetostriction with the maximum possible yield of rotated magnetic moments, which is achieved when λ∥ = λsat and λ⊥ = 0. The uniformity of the SA along the sample length and the impact of the SA on sensing/energy harvesting performance were then assessed by comparing pre- and post-SA bending-stress-induced changes in magnetization at five different locations along the samples. The SA process with a 150 MPa compressive load improved Fe-Ga actuation along the sample length from 170 to 225 ppm (from ∼60% to within ∼80% of λsat. The corresponding sensing/energy harvesting performance improved by as much as a factor of eight in the best sample, however the improvement was not at all uniform along the sample length. The SA process with a 100 MPa compressive load improved Fe-Al actuation along the sample length from 60 to 73 ppm (from ∼46% to ∼56% of λsat, indicating only a marginally effective SA and suggesting the need for modification of the SA protocol. In spite of this, the SA was effective at improving the sensing/energy

  20. [Cosmic Microwave Background (CMB) Anisotropies

    Science.gov (United States)

    Silk, Joseph

    1998-01-01

    One of the main areas of research is the theory of cosmic microwave background (CMB) anisotropies and analysis of CMB data. Using the four year COBE data we were able to improve existing constraints on global shear and vorticity. We found that, in the flat case (which allows for greatest anisotropy), (omega/H)0 less than 10-7, where omega is the vorticity and H is the Hubble constant. This is two orders of magnitude lower than the tightest, previous constraint. We have defined a new set of statistics which quantify the amount of non-Gaussianity in small field cosmic microwave background maps. By looking at the distribution of power around rings in Fourier space, and at the correlations between adjacent rings, one can identify non-Gaussian features which are masked by large scale Gaussian fluctuations. This may be particularly useful for identifying unresolved localized sources and line-like discontinuities. Levin and collaborators devised a method to determine the global geometry of the universe through observations of patterns in the hot and cold spots of the CMB. We have derived properties of the peaks (maxima) of the CMB anisotropies expected in flat and open CDM models. We represent results for angular resolutions ranging from 5 arcmin to 20 arcmin (antenna FWHM), scales that are relevant for the MAP and COBRA/SAMBA space missions and the ground-based interferometer. Results related to galaxy formation and evolution are also discussed.