WorldWideScience

Sample records for bremsstrahlung magnetic

  1. Strong linear polarization of bremsstrahlung emissivity in photospheres of magnetic white dwarfs

    Energy Technology Data Exchange (ETDEWEB)

    Bubukina, I I; Koryagin, S A, E-mail: koryagin@appl.sci-nnov.r [Institute of Applied Physics of the Russian Academy of Sciences, 46 Uljanova str., Nizhny Novgorod 603950 (Russian Federation)

    2009-06-01

    We discuss the strong linear polarization and the appreciable decrease of the bremsstrahlung emissivity at frequencies below the electron cyclotron frequency (infrared wave band) in the photospheres of the isolated magnetic white dwarfs. In the photospheres of strongly magnetized white dwarfs (B > 10{sup 7} G, T approx 10{sup 4} K), the electron's Larmor radius becomes smaller than the characteristic impact parameter of close Coulomb collisions in a non-magnetized plasma. Thus, the cyclotron period of the electron becomes smaller than the duration of all distant collisions and of most close collisions. The magnetic field effectively 'freezes' the electron motion in the plane transverse to the magnetic field lines. The resulting motion is nearly one-dimensional and parallel to the magnetic field, inducing a strong linear polarization of the bremsstrahlung emission. Being attached to a magnetic field line, an electron cannot approach an ion as closely as it does in the case in which the magnetic field is absent. Thus, the bremsstrahlung emissivity appreciably decreases. We analytically compute an approximation to the spectrum of the strongly linear polarized bremsstrahlung emissivity at the frequencies below the electron cyclotron frequency.

  2. Model of the bremsstrahlung emission accompanying interactions between protons and nuclei from low up to intermediate energies: role of magnetic emission

    CERN Document Server

    Maydanyuk, Sergei P

    2012-01-01

    A new model of the bremsstrahlung emission which accompanies proton decay and collisions of protons off nuclei in the energy region from the lowest up to intermediate, has been developed. This model includes spin formalism, potential approach for description of interaction between protons and nuclei, and operator of emission includes component of the magnetic emission (defined on the basis of Pauli equation). In the problem of the bremsstrahlung during the proton decay in the first time a role of the magnetic emission is studied using such a model. For the studied $^{146}{\\rm Tm}$ nucleus it has been studied the following: (1) How much does the magnetic emission change the full bremsstrahlung spectrum? (2) At which angle is the magnetic emission the most intensive relatively electric one? (3) Is there some space region where the magnetic emission increases strongly relatively electric one? (4) How intensive is the magnetic emission in the tunneling region? (5) Which values has the probability at its maximum a...

  3. Model for bremsstrahlung emission accompanying interactions between protons and nuclei from low energies up to intermediate energies: Role of magnetic emission

    Science.gov (United States)

    Maydanyuk, Sergei P.

    2012-07-01

    A model of the bremsstrahlung emission which accompanies proton decay and collisions of protons off nuclei in the low- to intermediate-energy region has been developed. This model includes spin formalism, a potential approach for describing the interaction between protons and nuclei, and an emission that includes a component of the magnetic emission (defined on the basis of the Pauli equation). For the problem of bremsstrahlung during proton decay the role of magnetic emission is studied by using such a model. For the 146Tm nucleus the following has been studied: (1) How much does the magnetic emission change the full bremsstrahlung spectrum? (2) At which angle is the magnetic emission the most intensive relative to the electric emission? (3) Is there some spatial region where the magnetic emission increases strongly relative to the electric emission? (4) How intensive is the magnetic emission in the tunneling region? (5) Which is the maximal probability? Which value does it equal to at the zero-energy limit of the emitted photons? It is demonstrated that the model is able to describe well enough experimental data of bremsstrahlung emission which accompanies collisions of protons off 9C, 64Cu, and 107Ag nuclei at an incident energy of Tlab=72 MeV (at a photon energy up to 60 MeV) and off 9Be, 12C, and 208Pb nuclei at an incident energy of Tlab=140 MeV (at a photon energy up to 120 MeV).

  4. Polarization Bremsstrahlung

    CERN Document Server

    Korol, Andrey V

    2014-01-01

    This book introduces and reviews both theory and applications of polarizational bremsstrahlung, i.e. the electromagnetic radiation emitted during collisions of charged particles with structured, thus polarizable targets, such as atoms, molecules and clusters.   The subject, following the first experimental evidence a few decades ago, has gained importance through a number of modern applications.  Thus, the study of several radiative mechanisms is expected to lead to the design of novel light sources, operating in various parts of the electromagnetic spectrum. Conversely, the analysis of the spectral and angular distribution of the photon emission constitutes a new tool for extracting information on the interaction of the colliding particles, and on their internal structure and dynamical properties.   Last but not least, accurate quantitative descriptions of the photon emission processes determine the radiative energy losses of particles in various media, thereby providing essential  information required f...

  5. Bremsstrahlung in $\\alpha$ Decay

    CERN Document Server

    Takigawa, N; Hagino, K; Ono, A; Brink, D M

    1999-01-01

    A quantum mechanical analysis of the bremsstrahlung in $\\alpha$ decay of $^{210}$Po is performed in close reference to a semiclassical theory. We clarify the contribution from the tunneling, mixed, outside barrier regions and from the wall of the inner potential well to the final spectral distribution, and discuss their interplay. We also comment on the validity of semiclassical calculations, and the possibility to eliminate the ambiguity in the nuclear potential between the alpha particle and daughter nucleus using the bremsstrahlung spectrum.

  6. A measurement of the magnetic dipole moment of the. delta. /sup + +/(1232) from the bremsstrahlung process. pi. p. -->. pi. p. gamma

    Energy Technology Data Exchange (ETDEWEB)

    Meyer, C.A.

    1987-06-01

    We have measured the cross section from the bremsstrahlung process ..pi../sup +/p ..-->.. ..pi../sup +/p..gamma.. for incident pions of energy 299 MeV. We detected the out going pion in the angular range from 55 to 95/sup 0/ in the lab, and photons were detected near 240/sup 0/ in the lab. We compare this measured cross-section to the MIT theory in order to extract a measurement of the magnetic dipole moment of the ..delta../sup + +/(1232), ..mu../sub ..delta../. In order to compare our results with the MIT theory, we have folded the MIT theory into the acceptance of our apparatus. We find that for pion angles between 55 and 75/sup 0/ the theory gives us a dipole moment of: 2.3..mu../sub p/ < ..mu../sub ..delta../ < 3.3..mu../sup p/ where the quoted error arises from an experimental uncertainty of +-0.25..mu../sub p/ and from theoretical uncertainties of +-0.25 ..mu../sub p/. However, for pion angles between 75 and 95/sup 0/ we find that the MIT theory predicts a cross-section which is larger than our measured cross-section, and makes it difficult to extract a value of ..mu../sub ..delta../. This over prediction is not understood, but consistent with a similar effect when the MIT theory is fit to previous data. 78 figs., 29 tabs.

  7. Runaway electrons and Bremsstrahlung

    Science.gov (United States)

    Helander, Per

    2016-09-01

    If an electric field is applied to a plasma, it causes ‘runaway’ acceleration of some electrons—a phenomenon that has been known for almost a century. A paper by Embréus et al (2016 New J. Phys. 18 093023) calculates how the emission of Bremsstrahlung affects the upper end of the energy spectrum of these electrons, and finds that it is important to carefully account for finite energy of the emitted photons.

  8. Simulation of Bremsstrahlung production

    Energy Technology Data Exchange (ETDEWEB)

    Patau, J.P.; Malbert, M.; Terrissol, M. (Centre de Physique Atomique, Toulouse (France))

    1981-10-01

    Electron slowing down and related phenomena are often greatly affected by bremsstrahlung production. Each creation of photon is individually simulated on the basis of a cross-section pack advised by Koch and Motz with corrections in the high energy frequency limit region. An accurate and fast sampling method is described. Its applicability covers a range between 50 keV and 80 MeV for target atoms whose atomic number is from 5 up to 90.

  9. Polarization bremsstrahlung in α decay

    International Nuclear Information System (INIS)

    A mechanism of formation of electromagnetic radiation that accompanies α decay and is associated with the emission of photons by electrons of atomic shells due to the scattering of α particles by these atoms (polarization bremsstrahlung) is proposed. It is shown that, when the photon energy is no higher than the energy of K electrons of an atom, polarization bremsstrahlung makes a significant contribution to the bremsstrahlung in α decay

  10. Creation of high energy bremsstrahlung and intensity by a multitarget and refocusing of the scattered electrons by small-angle backscatter at the wall of a cone and magnetic fields

    CERN Document Server

    Ulmer, W

    2011-01-01

    The yield of bremsstrahlung from collisions of fast electrons (energy at least 6 MeV) with a tungsten target can be significantly improved by exploitation of Tungsten wall scatter in a multi-layered target. The Tungsten wall can serve to refocuse small angle scattered electrons. It is necessary that the thickness of one Tungsten layer does not exceed 0.02 mm. Further refocusing of electrons results from suitable magnetic fields with field strength between 0.5 Tesla and 6 Tesla (if the cone with multi-layered targets is rather narrow). Linear accelerators in radiation therapy only need refocusing by wall scatter without further magnetic fields (standard case: ca. 100 - 000 plates with 0.01 mm thickness and 1 mm distance between the plates). The construction of a very narrow bremsstrahlung beam with extremely high photon intensity requires an additional strong magnetic field (order 1 - 6 Tesla), which provides the possibility to check Heisenberg-Euler scatter of high energy photons.

  11. EXPERIMENTAL SET UP TO MEASURE COHERENT BREMSSTRAHLUNG AND BEAM PROFILES IN RHIC.

    Energy Technology Data Exchange (ETDEWEB)

    TRBOJEVIC,D.; GASNER,D.; MACKAY,W.; MCINTYRE,G.; PEGGS,S.; TEPIKIAN,S.; SERBO,V.; KOTKIN,G.

    2002-06-03

    A proposal for an experiment to detect and measure with an array infrared detector either the infrared radiation from the beam-beam coherent bremsstrahlung or from the synchrotron light from the edge effect of large DX RHIC magnet is described. Predictions for the 100 GeV/nucleon gold and 250 GeV proton signals from both bremsstrahlung and synchtrotron radiation magnet edge effect are shown.

  12. Coherence effects in nuclear bremsstrahlung

    NARCIS (Netherlands)

    Lohner, H

    2002-01-01

    The production of nuclear bremsstrahlung (Egamma > 30 MeV) has been studied in heavy-ion collisions, as well as proton and alpha-particle collisions with nuclei. In heavy-ion reactions the measured photon spectra show an exponential shape dominated by the incoherent sum of photons produced in first-

  13. Radiative corrections to pion-nucleus bremsstrahlung

    CERN Document Server

    Kaiser, N

    2008-01-01

    We calculate the one-photon loop radiative corrections to virtual pion Compton scattering $\\pi^- \\gamma^* \\to \\pi^- \\gamma$, that subprocess which determines in the one-photon exchange approximation the pion-nucleus bremsstrahlung reaction $\\pi^- Z\\to \\pi^- Z \\gamma$. Ultraviolet and infrared divergencies of the loop integrals are both treated by dimensional regularization. Analytical expressions for the ${\\cal O}(\\alpha)$ corrections to the virtual Compton scattering amplitudes, $A(s,u,Q)$ and $B(s,u,Q)$, are derived with their full dependence on the (small) photon virtuality $Q$ from 9 classes of contributing one-loop diagrams. Infrared finiteness of these virtual radiative corrections is achieved (in the standard way) by including soft photon radiation below an energy cut-off $\\lambda$. In the region of low $\\pi^- \\gamma$ center-of-mass energies, where the pion-nucleus bremsstrahlung process is used to extract the pion electric and magnetic polarizabilities, we find radiative corrections up to about -3% fo...

  14. Ultrahigh-intensity inverse bremsstrahlung

    Science.gov (United States)

    Kostyukov, I. Yu.; Rax, J.-M.

    1999-01-01

    We study inverse bremsstrahlung in the ultrahigh intensity relativistic regime. The fully relativistic ultrahigh intensity absorption (emission) coefficient is derived for an arbitrary scattering potential and small-angle scattering. We find that in the Coulomb field case this absorption (emission) coefficient can be calculated as a function of the quiver energy, drift momentum, and impact parameter in two complementary regimes: (i) for remote collisions when the impact parameter is larger than the amplitude of the quiver motion, and (ii) for instantaneous collisions when the scattering time is shorter than the period of the wave. Both circular and linear polarizations are considered, and this study reveals that in this relativistic regime inverse bremsstrahlung absorption can be viewed as a harmonic Compton resonance heating of the laser-driven electron by the virtual photon of the ion Coulomb field. The relativistic modification of Marcuse's effect [Bell Syst. Tech. J. 41, 1557 (1962)] are also discussed, and relations with previous nonrelativistic results are elucidated.

  15. Coulomb correction calculations of pp Bremsstrahlung

    International Nuclear Information System (INIS)

    The effects of the Coulomb interaction upon the photon cross section and analyzing power from pp Bremsstrahlung have been studied in detail. Off-shell properties of the Coulomb T matrices have been considered but the associated, Coulomb modified, hadronic T matrices are important elements in any analyses of low energy, forward proton scattering data. At the lowest energy considered (5 MeV), the full calculations gave cross sections that were half the size of those found without Coulomb effects or with a simple model approximation to them. With increasing energy, the cross sections varied to those characteristic of magnetic interaction dominance and the specific differences due to Coulomb effects diminished. 47 refs., 7 figs

  16. Diffractive Bremsstrahlung in Hadronic Collisions

    Directory of Open Access Journals (Sweden)

    Roman Pasechnik

    2015-01-01

    Full Text Available Production of heavy photons (Drell-Yan, gauge bosons, Higgs bosons, and heavy flavors, which is treated within the QCD parton model as a result of hard parton-parton collision, can be considered a bremsstrahlung process in the target rest frame. In this review, we discuss the basic features of the diffractive channels of these processes in the framework of color dipole approach. The main observation is a dramatic breakdown of diffractive QCD factorisation due to the interplay between soft and hard interactions, which dominates these processes. This observation is crucial for phenomenological studies of diffractive reactions in high energy hadronic collisions.

  17. Diffractive bremsstrahlung in hadronic collisions

    CERN Document Server

    Pasechnik, Roman; Potashnikova, Irina

    2015-01-01

    Production of heavy photons (Drell-Yan), gauge bosons, Higgs bosons, heavy flavors, which is treated within the QCD parton model as a result of hard parton-parton collision, can be considered as a bremsstrahlung process in the target rest frame. In this review, we discuss the basic features of the diffractive channels of these processes in the framework of color dipole approach. The main observation is a dramatic breakdown of diffractive QCD factorisation due to the interplay between soft and hard interactions, which dominates these processes. This observation is crucial for phenomenological studies of diffractive reactions in high-energy hadronic collisions.

  18. External bremsstrahlung spectra excited by 204Tl β particles in thick targets

    Science.gov (United States)

    Powar, M. S.; Ahmad, Salim; Singh, M.

    1980-06-01

    Spectral distributions of bremsstrahlung produced by 204Tl β particles in thick targets of Perspex, aluminum, copper, tin, and lead have been measured in a sandwich geometry. The contributions of internal bremsstrahlung produced along with the β particles have been determined by magnetic field deflection as well as the Z=O extrapolation method. Experimental results agree with Bethe-Heitler Born-approximation theory, corrected for Coulomb-field effects for low- and medium-Z targets, but show 25% positive deviation for high-Z targets. Again it is found that the bremsstrahlung produced in low-Z targets like Perspex is comparable with internal bremsstrahlung, and the corrections for its contribution to measurements by earlier workers can lead to large uncertainties.

  19. Polarizational bremsstrahlung in non-relativistic collision

    CERN Document Server

    Korol, A V

    2004-01-01

    We review the developments made during the last decade in the theory of polarization bremsstrahlung in the non-relativistic domain. A literature survey covering the latest history of the phenomenon is given. The main features which distinguish the polarization bremsstrahlung from other mechanisms of radiation are discussed and illustrated by the results of numerical calculations.

  20. Neutrino-pair bremsstrahlung in a neutron star crust

    CERN Document Server

    Ofengeim, D D; Yakovlev, D G

    2014-01-01

    Based on the formalism by Kaminker et al. (Astron. Astrophys. 343 (1999) 1009) we derive an analytic approximation for neutrino-pair bremsstrahlung emissivity due to scattering of electrons by atomic nuclei in the neutron star crust of any realistic composition. The emissivity is expressed through generalized Coulomb logarithm which we fit by introducing an effective potential of electron-nucleus scattering. In addition, we study the conditions at which the neutrino bremsstrahlung in the crust is affected by strong magnetic fields. The results can be applied for modelling of many phenomena in neutron stars, such as thermal relaxation in young isolated neutron stars and in accreting neutron stars with overheated crust in soft X-ray transients.

  1. Nuclear structure effects in high-energy bremsstrahlung from spin-0 and spin-1/2 nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Jakubassa-Amundsen, Doris [University of Munich (Germany)

    2014-07-01

    Bremsstrahlung from relativistic spin-polarized electrons colliding with inert nuclei is calculated by taking into account the nuclear form factors and the kinematical recoil. For the spin-1/2 nuclei additional contributions from the anomalous magnetic moment and the dynamical recoil are considered. Electron bremsstrahlung is described with the help of semirelativistic wavefunctions while nuclear bremsstrahlung, when present, is treated within the Born approximation. The triply differential bremsstrahlung cross section is integrated over the electron scattering angle to study the polarization correlations between the beam electron and the emitted photon. Results are shown for 20-120 MeV electrons colliding with protons, 19F, 64Zn and 89Y. It is also attempted to explain the background in electron spectra from nuclear excitation in terms of bremsstrahlung. As an example the 180 degree spectrum from exciting the giant M2 resonance in 90Zr by 42.7 MeV electrons is analyzed.

  2. Analytic approximate radiation effects due to Bremsstrahlung

    Energy Technology Data Exchange (ETDEWEB)

    Ben-Zvi I.

    2012-02-01

    The purpose of this note is to provide analytic approximate expressions that can provide quick estimates of the various effects of the Bremsstrahlung radiation produced relatively low energy electrons, such as the dumping of the beam into the beam stop at the ERL or field emission in superconducting cavities. The purpose of this work is not to replace a dependable calculation or, better yet, a measurement under real conditions, but to provide a quick but approximate estimate for guidance purposes only. These effects include dose to personnel, ozone generation in the air volume exposed to the radiation, hydrogen generation in the beam dump water cooling system and radiation damage to near-by magnets. These expressions can be used for other purposes, but one should note that the electron beam energy range is limited. In these calculations the good range is from about 0.5 MeV to 10 MeV. To help in the application of this note, calculations are presented as a worked out example for the beam dump of the R&D Energy Recovery Linac.

  3. Relativistic Non-Thermal Bremsstrahlung Radiation

    CERN Document Server

    Zeković, Vladimir; Dobardzić, Aleksandra; Pavlović, Marko

    2013-01-01

    By applying a method of virtual quanta we derive formulae for relativistic non-thermal bremsstrahlung radiation from relativistic electrons as well as from protons and heavier particles with power-law momentum distribution $N(p)dp = k p^{-q} dp.$ We show that emission which originates from an electron scattering on an ion, represents the most significant component of relativistic non-thermal bremsstrahlung. Radiation from an ion scattering on electron, known as inverse bremsstrahlung, is shown to be negligible in overall non-thermal bremsstrahlung emission. These results arise from theory refinement, where we introduce the dependence of relativistic kinetic energy of an incident particle, upon the energy of scattered photon. In part, it is also a consequence of a different mass of particles and relativistic effects.

  4. Coherent bremsstrahlung at colliding beams

    Energy Technology Data Exchange (ETDEWEB)

    Ginzburg, I.F. (Inst. of Mathematics, Novosibirsk (Russia)); Kotkin, G.L.; Serbo, V.G. (Novosibirsk State Univ. (Russia)); Polityko, S.I. (Irkutsk State Univ. (Russia))

    1992-07-30

    We consider a new type of radiation at colliders with short bunches - coherent bremsstrahlung (CBS). CBS can be treated as radiation of the first bunch particles caused by the collective electromagnetic field of the short second bunch. A general method for the calculation of this CBS is presented. The number of CBS photons per single collision is dN{sub {gamma}}{approx equal}N{sub 0}dE{sub {gamma}}/E{sub {gamma}} in the energy range E{sub {gamma}}

  5. Anomalous fluorescence line intensity in megavoltage bremsstrahlung

    Science.gov (United States)

    Pereira, Nino; Litz, Marc; Merkel, George; Schumer, Joseph; Seely, John; Carroll, Jeff

    2009-11-01

    A Cauchois transmission crystal spectrometer intended for laser plasma diagnostics has measured an anomalous ratio between the fluorescence lines in megavoltage bremsstrahlung. When observed in reflection, Kα1 fluorescence is twice as strong as the Kβ line, as is usual. However, in forward-directed bremsstrahlung from a 2 MV end point linear accelerator with a tungsten converter, the Kα1 and Kβ fluorescence are approximately equal. The anomalous fluorescence line ratio, unity, reflects the large amount of fluorescence generated on the side of the converter where the electrons enter, and the differential attenuation of the fluorescence photons as they pass through the converter to opposite side. Understanding of fluorescence in megavoltage bremsstrahlung is relevant to the explanation of anomalous line ratios in spectra produced by high-energy electrons generated by intense femtosecond laser irradiation.

  6. Radiative Corrections to High Energy Lepton Bremsstrahlung on Heavy Nuclei

    CERN Document Server

    Arbuzov, A B

    2008-01-01

    One-loop radiative corrections to the leptonic tensor in high energy bremsstrahlung on heavy nuclei are calculated. Virtual and real photon radiation is taken into account. Double bremsstrahlung is simulated by means of Monte Carlo. Numerical results are presented for the case of muon bremsstrahlung in conditions of the COMPASS experiment at CERN.

  7. 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...

  8. Goniometer Control System for Coherent Bremsstrahlung Production

    Science.gov (United States)

    Acousta, V. M.

    2002-08-01

    A system for the generation of a high-intensity, quasi-monochromatic photon beam is discussed. The theory behind coherent bremsstrahlung photon beam production is analyzed and developed. The mechanics of a goniometer control system are presented. The software developed for remote control of the goniometer is also discussed. Finally, the results from various performance measurements are included.

  9. Bremsstrahlung from relativistic heavy ions in matter

    DEFF Research Database (Denmark)

    Sørensen, Allan Hvidkjær

    2010-01-01

     MeV for a lead ion (γ≡E/Mc2 is the Lorentz factor of the projectile of energy E and mass M). The maximum exceeds the bremsstrahlung from a hypothetical structureless, pointlike particle of the same charge and mass as the incoming nucleus, but rapid depletion follows on the high-energy side of the peak...

  10. Modeling the bremsstrahlung emission from converters

    CERN Document Server

    Mirea, M; Clapier, F; Hassaïne, M; Ibrahim, F; Müller, A C; Pauwels, N; Proust, J; Verney, D; Antoni, R; Bourgeois, L; Kandri-Rody, S

    2001-01-01

    The bremsstrahlung angular and energy theoretical distributions delivered from W and UCx thick converters are reported. This study is focussed on initial kinetic energies of the electron beam included in the range 30-60 MeV, suitable for the production of large radiative yields able to induce the $^{238}$U fission. These results offer the possibility to evaluate the required shielding for a neutron rich nuclei source.

  11. Bremsstrahlung Radiation At a Vacuum Bubble Wall

    CERN Document Server

    Lee, Jae-Weon; Lee, Chul H; Jang, Ji-ho

    2007-01-01

    When charged particles collide with a vacuum bubble, they can radiate strong electromagnetic waves due to rapid deceleration. Owing to the energy loss of the particles by this bremsstrahlung radiation, there is a non-negligible damping pressure acting on the bubble wall even when thermal equilibrium is maintained. In the non-relativistic region, this pressure is proportional to the velocity of the wall and could have influenced the bubble dynamics in the early universe.

  12. Radiative corrections to pion-nucleus bremsstrahlung

    OpenAIRE

    Kaiser, N.(Physik Department T39, Technische Universität München, Garching, D-85747, Germany); Friedrich, J. M.

    2008-01-01

    We calculate the one-photon loop radiative corrections to virtual pion Compton scattering $\\pi^- \\gamma^* \\to \\pi^- \\gamma$, that subprocess which determines in the one-photon exchange approximation the pion-nucleus bremsstrahlung reaction $\\pi^- Z\\to \\pi^- Z \\gamma$. Ultraviolet and infrared divergencies of the loop integrals are both treated by dimensional regularization. Analytical expressions for the ${\\cal O}(\\alpha)$ corrections to the virtual Compton scattering amplitudes, $A(s,u,Q)$ a...

  13. The LPM effect in sequential bremsstrahlung

    CERN Document Server

    Arnold, Peter

    2015-01-01

    The splitting processes of bremsstrahlung and pair production in a medium are coherent over large distances in the very high energy limit, which leads to a suppression known as the Landau-Pomeranchuk-Migdal (LPM) effect. We analyze the case when the coherence lengths of two consecutive splitting processes overlap, which is important for understanding corrections to standard treatments of the LPM effect in QCD. Previous authors have analyzed this problem in the case of overlapping double bremsstrahlung where at least one of the bremsstrahlung gluons is soft. Here we show how to generalize to include the case where both splittings are hard. A number of techniques must be developed, and so in this paper we simplify by (i) restricting attention to a subset of the interference effects, which we call the "crossed" diagrams, and (ii) working in the large-$N_c$ limit. We first develop some general formulas that could in principle be implemented numerically (with substantial difficulty). To make more analytic progress...

  14. Thermal Bremsstrahlung Radiation in a Two-Temperature Plasma

    OpenAIRE

    Luo, Bin; Zhang, S. Nan

    2002-01-01

    In the normal one-temperature plasma the motion of ions is usually neglected when calculating the Bremsstrahlung radiation of the plasma. Here we calculate the Bremsstrahlung radiation of a two-temperature plasma by taking into account of the motion of ions. Our results show that the total radiation power is always lower if the motion of ions is considered. We also apply the two-temperature Bremsstrahlung radiation mechanism for an analytical Advection-Dominated Accretion Flow (ADAF) model; w...

  15. Thermal Bremsstrahlung Radiation in a Two-Temperature Plasma

    Institute of Scientific and Technical Information of China (English)

    Bin Luo; Shuang-Nan Zhang

    2004-01-01

    In normal one-temperature plasma the motion of ions is usually neglected when calculating the Bremsstrahlung radiation of the plasma.We calculate the Bremsstrahlung radiation of a two-temperature plasma by taking into account of the motion of ions.Our results show that the total radiation power is always lower if the motion of ions is considered.We also apply the two-temperature Bremsstrahlung radiation mechanism for an analytical Advection-Dominated Accretion Flow(ADAF)model:we find the two-temperature correction to the total Bremsstrahlung radiation for ADAF is negligible.

  16. Internal bremsstrahlung spectrum of 139Ce

    International Nuclear Information System (INIS)

    The internal bremsstrahlung spectrum which accompanies the electron capture decay of 139Ce to the first excited state of 139La has been measured in coincidence with the nuclear gamma ray which deexcites that state. The measured intensity above 42 keV is found to be (1.070±0.024) times that predicted by the recent calculations of Suriacute c et al. The QEC value is found to be 264.6±2.0 keV. copyright 1996 The American Physical Society

  17. Vector dark matter annihilation with internal bremsstrahlung

    OpenAIRE

    Bambhaniya, Gulab; Kumar, Jason; Marfatia, Danny; Nayak, Alekha C.; Tomar, Gaurav

    2016-01-01

    We consider scenarios in which the annihilation of self-conjugate spin-1 dark matter to a Standard Model fermion-antifermion final state is chirality suppressed, but where this suppression can be lifted by the emission of an additional photon via internal bremsstrahlung. We find that this scenario can only arise if the initial dark matter state is polarized, which can occur in the context of self-interacting dark matter. In particular, this is possible if the dark matter pair forms a bound st...

  18. Time evolution of endpoint energy of Bremsstrahlung spectra and ion production from an electron cyclotron resonance ion source

    Energy Technology Data Exchange (ETDEWEB)

    Tarvainen, Ollie [Los Alamos National Laboratory; Ropponen, Tommi [JYFL; Jones, Peter [JYFL; Kalvas, Taneli [JYFL

    2008-01-01

    Electron cyclotron resonance ion sources (ECRIS) are used to produce high charge state heavy ion beams for the use of nuclear and materials science, for instance. The most powerful ECR ion sources today are superconducting. One of the problems with superconducting ECR ion sources is the use of high radio frequency (RF) power which results in bremsstrahlung radiation adding an extra heat load to the cryostat. In order to understand the electron heating process and timescales in the ECR plasma, time evolution measurement of ECR bremsstrahlung was carried out. In the measurements JYFL 14 GHz ECRIS was operated in a pulsed mode and bremsstrahlung data from several hundred RF pulses was recorded. Time evolution of ion production was also studied and compared to one of the electron heating theories. To analyze the measurement data at C++ program was developed. Endpoint energies of the bremsstrahlung spectra as a function of axial magnetic field strength, pressure and RF power are presented and ion production timescales obtained from the measurements are compared to bremsstrahlung emission timescales and one of the stochastic heating theories.

  19. Coherent bremsstrahlung used for digital subtraction angiography

    Science.gov (United States)

    Überall, Herbert

    2007-05-01

    Digital subtraction angiography (DSA), also known as Dichromography, using synchrotron radiation beams has been developed at Stanford University (R. Hofstadter) and was subsequently taken over at the Brookhaven Synchrotron and later at Hamburg (HASYLAB) [see, e.g., W.R. Dix, Physik in unserer Zeit. 30 (1999) 160]. The imaging of coronary arteries is carried out with an iodine-based contrast agent which need not be injected into the heart. The radiation must be monochromatized and is applied above and below the K-edge of iodine (33.16 keV), with a subsequent digital subtraction of the two images. Monochromatization of the synchrotron radiation causes a loss of intensity of 10 -3. We propose instead the use of coherent bremsstrahlung [see, e.g., A.W. Saenz and H. Uberall, Phys. Rev. B25 (1982) 448] which is inherently monochromatic, furnishing a flux of 10 12 photon/sec. This requires a 10-20 MeV electron linac which can be obtained by many larger hospitals, eliminating the scheduling problems present at synchrotrons. The large, broad incoherent bremsstrahlung background underlying the monochromatic spike would lead to inadmissible overexposure of the patient. This problem can be solved with the use of Kumakhov's capillary optics [see e.g., S.B.Dabagov, Physics-Uspekhi 46 (2003) 1053]: the low-energy spiked radiation can be deflected towards the patient, while the higher energy incoherent background continues forward, avoiding the patient who is placed several meters from the source.

  20. Coherent bremsstrahlung at the HERA collider

    Energy Technology Data Exchange (ETDEWEB)

    Ginzberg, I.F. (Inst. of Mathematics, Novosibirsk (Russian Federation)); Kotkin, G.L. (Novosibirsk State Univ. (Russian Federation)); Polityko, S.I. (Irkutsk State Univ. (Russian Federation)); Serbo, V.G. (Irkutsk State Univ. (Russian Federation))

    1993-12-01

    We consider a new type of radiation at colliders with short bunches - coherent bremsstrahlung (CBS) which is the radiation of the first bunch particles caused by the collective electromagnetic field of the second bunch. The number of CBS photons for a single collision is dN[sub y][approx]N[sub 0]dE[sub y]/E[sub y] in the energy range E[sub y]< or [approx]E[sub c]=4y[sub 1][sup 2]hc/l[sub 2]. Here y[sub 1]=E[sub 1]/m[sub 1]c[sup 2]; l[sub 2] is the length of the opposing (second) bunch and N[sub 0] is proportional to N[sub 1]N[sub 2][sup 2] where N[sub j] is the j-th bunch population. For the HERA collider N[sub 0]=14, E[sub c]=73 eV in the case when photons are emitted by protons and N[sub 0]=6.10[sup 7], E[sub c]=24 keV - when photons are emitted by electrons. Unusual properties of such a coherent bremsstrahlung and the possibility to use CBS for fast beam steering and for luminosity optimization are discussed. (orig.)

  1. Bremsstrahlung spectra from atoms and ions at low relativistic energies

    International Nuclear Information System (INIS)

    Analytic expressions for bremsstrahlung spectra from neutral atoms and ions, including the polarizational bremsstrahlung contribution in a stripped atom approximation, are developed for electron scattering at energies of 10-2000 keV. A modified Elwert factor and a simple higher Born correction are used for the Coulomb spectrum, with ordinary bremsstrahlung screening effects in ions and atoms adequately characterized in the non-relativistic Born approximation. In parallel with the development of this analytic description, new numerical results are obtained for ordinary bremsstrahlung from ions and from bare nuclei, appreciably extending the available data set which can be used to study dependences on element, ionicity, energy and the fraction of incident energy radiated. The accuracy of predictions with the analytic expressions is then determined by comparison with the full numerical relativistic partial-wave results for ordinary bremsstrahlung and with non-relativistic numerical results in the Born approximation or in partial waves for the polarizational amplitude. (author)

  2. Polarization of thermal bremsstrahlung emission due to electron pressure anisotropy

    Science.gov (United States)

    Komarov, S. V.; Khabibullin, I. I.; Churazov, E. M.; Schekochihin, A. A.

    2016-09-01

    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 ˜0.1 per cent at energies ≳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 scales, which are impossible to resolve spatially. The absence of the effect at the predicted level may set a lower limit on the electron collisionality in the ICM. At the same time, the small value of the effect implies that it does not preclude the use of clusters as (unpolarized) calibration sources for X-ray polarimeters at this level of accuracy.

  3. Dynamical model for Pion-Nucleon Bremsstrahlung

    CERN Document Server

    Mariano, A V

    2000-01-01

    A dynamical model based on effective Lagrangians is proposed to describe the bremsstrahlung reaction $ \\pi N \\to \\pi N \\gamma$ at low energies. The $\\Delta(1232)$ degrees of freedom are incorporated in a way consistent with both, electromagnetic gauge invariance and invariance under contact transformations. The model also includes the initial and final state rescattering of hadrons via a T-matrix with off-shell effects. The $\\pi N \\gamma$ differential cross sections are calculated using three different T-matrix models and the results are compared with the soft photon approximation, and with experimental data. The aim of this analysis is to test the off-shell behavior of the different T-matrices under consideration.

  4. Vector dark matter annihilation with internal bremsstrahlung

    CERN Document Server

    Bambhaniya, Gulab; Marfatia, Danny; Nayak, Alekha C; Tomar, Gaurav

    2016-01-01

    We consider scenarios in which the annihilation of self-conjugate spin-1 dark matter to a Standard Model fermion-antifermion final state is chirality suppressed, but where this suppression can be lifted by the emission of an additional photon via internal bremsstrahlung. We find that this scenario can only arise if the initial dark matter state is polarized, which can occur in the context of self-interacting dark matter. In particular, this is possible if the dark matter pair forms a bound state that decays to its ground state before the constituents annihilate. We show that the shape of the resulting photon spectrum is the same as for self-conjugate spin-0 and spin-1/2 dark matter, but the normalization is less heavily suppressed in the limit of heavy mediators.

  5. Internal bremsstrahlung endpoint energy of 54Mn

    International Nuclear Information System (INIS)

    For 54Mn there is a discrepancy between the QEC obtained from the endpoint energy of the internal bremsstrahlung (IB) spectrum which accompanies the electron capture decay (QEC=1353±8 keV) and that obtained from the accepted mass differences (QEC=1377±1 keV). This Q value is needed to deduce the partial-half life of the astrophysically interesting β- decay of 54Mn from the recently measured β+ partial half-life. To resolve this discrepancy, we have remeasured the endpoint energy of the IB spectrum, by recording coincidences between the IB and the 835-keV γ ray, both detected in Compton-suppressed Ge detectors. The QEC we deduce is 1379±8 keV, in agreement with the accepted mass differences. (c) 2000 The American Physical Society

  6. Effect of bremsstrahlung radiation emission on fast electrons in plasmas

    Science.gov (United States)

    Embréus, O.; Stahl, A.; Fülöp, T.

    2016-09-01

    Bremsstrahlung radiation emission is an important energy loss mechanism for energetic electrons in plasmas. In this paper we investigate the effect of spontaneous bremsstrahlung emission on the momentum-space structure of the electron distribution, fully accounting for the emission of finite-energy photons by modeling the bremsstrahlung interactions with a Boltzmann collision operator. We find that electrons accelerated by electric fields can reach significantly higher energies than predicted by the commonly used radiative stopping-power model. Furthermore, we show that the emission of soft photons can contribute significantly to the dynamics of electrons with an anisotropic distribution by causing pitch-angle scattering at a rate that increases with energy.

  7. The LPM effect in sequential bremsstrahlung 2: factorization

    CERN Document Server

    Arnold, Peter; Iqbal, Shahin

    2016-01-01

    The splitting processes of bremsstrahlung and pair production in a medium are coherent over large distances in the very high energy limit, which leads to a suppression known as the Landau-Pomeranchuk-Migdal (LPM) effect. In this paper, we continue analysis of the case when the coherence lengths of two consecutive splitting processes overlap (which is important for understanding corrections to standard treatments of the LPM effect in QCD), avoiding soft-gluon approximations. In particular, this paper analyzes the subtle problem of how to precisely separate overlapping double splitting (e.g.\\ overlapping double bremsstrahlung) from the case of consecutive, independent bremsstrahlung (which is the case that would be implemented in a Monte Carlo simulation based solely on single splitting rates). As an example of the method, we consider the rate of real double gluon bremsstrahlung from an initial gluon with various simplifying assumptions (thick media; $\\hat q$ approximation; large $N_c$; and neglect for the mome...

  8. Bremsstrahlung spectra produced by kilovolt electron impact on thick targets

    International Nuclear Information System (INIS)

    Measurements of bremsstrahlung spectra generated by 5-25 keV electron impact on thick targets of aluminium, titanium, zirconium, molybdenum and tungsten are reported. The experimental data are compared with the simulation results of X-ray spectra obtained from the general-purpose Monte Carlo code PENELOPE, which implements accurate cross-sections for ordinary bremsstrahlung emission but disregards polarization bremsstrahlung. The agreement between the experimental and simulation results is satisfactory. This is in contrast with a recent study in which large discrepancies were observed between experimental and Monte Carlo simulation results. Our results provide evidence for the reliability of the combined choices of the interaction cross-sections and of the simulation algorithms implemented in PENELOPE for bremsstrahlung emission.

  9. Feasibility Studies of the Diffractive Bremsstrahlung Measurement at the LHC

    OpenAIRE

    J.J. Chwastowski; Czekierda, S.; Kycia, R.; Staszewski, R.(The Henryk Niewodniczanski Institute of Nuclear Physics, Polish Academy of Sciences, Kraków, Poland); Turnau, J.; Trzebiński, M

    2016-01-01

    Feasibility studies of an observation of the exclusive diffractive bremsstrahlung in proton-proton scattering at the LHC are reported. A simplified approach to the photon and the scattered proton energy reconstruction is used. The background influence is discussed.

  10. Calculation of the collimated bremsstrahlung flux from thin radiators

    International Nuclear Information System (INIS)

    A method is outlined for calculating the absolute flux of a bremsstrahlung beam created by passing an electron beam through thin radiators. Multiple scattering of the electron beam in the radiator and collimation of the bremsstrahlung flux are considered in this calculation. Separate measurements determine that this calculations has an absolute accuracy of 2.8% for an endpoint energy range from 120 to 360 MeV for a total radiator thickness of less than 0.012 radiation lengths. (orig.)

  11. Angular distribution of the bremsstrahlung emission during lower-hybrid current drive on PLT

    International Nuclear Information System (INIS)

    The bremsstrahlung emission from the PLT tokamak during lower-hybrid current drive has been measured as a function of angle between the magnetic field and the emission direction. The emission is peaked strongly in the forward direction, indicating a strong anisotropy of the electron-velocity distribution. The data demonstrate the existence of a nearly flat tail of the velocity distribution, which extends out to approximately 500 keV and which is interpreted as the plateau created by Landau damping of the lower-hybrid waves

  12. Sum rules for the polarization correlations in photoionization and bremsstrahlung

    Science.gov (United States)

    Pratt, R. H.; Müller, R. A.; Surzhykov, A.

    2016-05-01

    The polarization correlations in doubly differential cross sections are investigated for photoionization and ordinary bremsstrahlung. These correlations describe the polarization transfer between incident light and ejected photoelectrons as well as between an incoming electron beam and bremsstrahlung light, respectively. They are characterized by a set of seven real parameters Ci j. We show that the squares of these parameters are connected by simple "sum rules." These sum rules can be applied for both one-electron systems and also for atoms, if the latter are described within the independent particle approximation. In particular, they are exact in their simplest form (i) for the photoionization of K -, LI ,I I-, and MI ,I I-atomic shells, as well as (ii) for bremsstrahlung in which the electron is scattered into s1 /2 or p1 /2 states, as in the tip (bremsstrahlung) region. Detailed calculations are performed to verify the derived identities and to discuss their possible applications for the analysis of modern photoionization and bremsstrahlung experiments. In particular, we argue that the sum rules may help to determine the entire set of (significant) polarization correlations in the case when not all Ci j are available for experimental observation.

  13. Impulsive solar X-ray bursts. 3: Polarization and directivity of bremsstrahlung radiation from a beam of electrons directed toward the photosphere

    Science.gov (United States)

    Langer, S. H.; Petrosian, V.

    1976-01-01

    The spectrum, directivity and state of polarization is presented of the bremsstrahlung radiation expected from a beam of high energy electrons spiraling along radial magnetic field lines toward the photosphere. The results are used for calculation of the characteristics of the reflected plus direct flux.

  14. The development of a high power bremsstrahlung radiator for the production of monochromatic X-rays

    International Nuclear Information System (INIS)

    An experimental setup for the production of monochromatic X-ray beams tunable in the energy region between 75 KeV and 700 KeV was built at our facility. The concept is based on monochromatization of a broad energy bremsstrahlung spectrum by Laue diffraction on a curved single crystal and by selection of the desired energy with an appropriate slit system, 10.45 meters behind the crystal. The bremsstrahlung spectrum is created when accelerated electrons from a high power 20 kW linac lose energy in a radiator. In this study, the radiator has been optimized for the creation of a bremsstrahlung spectrum suitable for monochromatization with a crystal. Monte-Carlo Simulations (using the BEAM-EGS4 code) of electrons incident with different energies on a radiator with varying composition (aluminum, carbon and tantalum) and thickness were carried out. Furthermore a study of the thermal properties of these materials when being exposed to a high power electron beam was done. This lead to the remarkable conclusion that a thin radiator composed of a low Z material should be used. This result is quite surprising as usually a high Z material is used for efficient transformation of charged particle energy to bremsstrahlung photons. A low Z radiator however will create a less divergent photon beam, leading to more photons on the effective surface area of the crystal. A set of radiators was designed to have an optimal configuration for different monochromatic beams needed. Because only a small fraction of the electrons are stopped in these thin radiators, a cleaning magnet and a beamstop need to be inserted in the setup. Due to the high power of the electron beam on the one hand and its divergency after traversing the radiator on the other, a special magnet system had to be designed to remove the electrons from the photon beam. This was done by means of Monte-Carlo simulations and a ray tracing program. Finally it was estimated that, when using this new setup, the intensity of the

  15. Elastic photonuclear cross sections for bremsstrahlung from relativistic ions

    OpenAIRE

    Mikkelsen, R. E.; Sørensen, A H; Uggerhøj, U. I.

    2015-01-01

    In this paper, we provide a procedure to calculate the bremsstrahlung spectrum for virtually any relativistic bare ion with charge 6$e$ or beyond, $Z\\ge 6$, in ultraperipheral collisions with target nuclei. We apply the Weizs\\"{a}cker-Williams method of virtual quanta to model the effect of the distribution of nuclear constituents on the interaction of the ion with the radiation target. This leads to a bremsstrahlung spectrum peaking at $2\\gamma$ times the energy of the giant dipole resonance...

  16. Bremsstrahlung signatures of dark matter annihilation in the Sun

    CERN Document Server

    Fukushima, Keita; Kumar, Jason; Marfatia, Danny

    2012-01-01

    The nonrelativistic annihilation of Majorana dark matter in the Sun to a pair of light fermions is chirality-suppressed. Annihilation to 3-body final states $\\ell^+f^-V$, where $V=W,Z,\\gamma$, and $\\ell$ and $f$ are light fermions (that may be the same), becomes dominant since bremsstrahlung relaxes the chirality suppression. We evaluate the neutrino spectra at the source, including spin and helicity dependent effects, and assess the detectability of each significant bremsstrahlung channel at IceCube/DeepCore. We also show how to combine the sensitivities to the dark matter-nucleon scattering cross section in individual channels, since typically several channels contribute in models.

  17. Effect of bremsstrahlung radiation emission on fast electrons in plasmas

    CERN Document Server

    Embréus, Ola; Fülöp, Tünde

    2016-01-01

    Bremsstrahlung radiation emission is an important energy loss mechanism for energetic electrons in plasmas. In this paper we investigate the effect of spontaneous bremsstrahlung emission on the momentum-space structure of the electron distribution, fully accounting for the emission of finite-energy photons. We find that electrons accelerated by electric fields can reach significantly higher energies than what is expected from energy-loss considerations. Furthermore, we show that the emission of soft photons can contribute significantly to the dynamics of electrons with an anisotropic distribution.

  18. Revisiting Bremsstrahlung emission associated with Light Dark Matter annihilations

    OpenAIRE

    Boehm, C; Uwer, P.

    2006-01-01

    We compute the single bremsstrahlung emission associated with the pair annihilation of spin-0 particles into electrons and positrons, via the t-channel exchange of a heavy fermion. We compare our result with the work of Beacom et al. . Unlike what is stated in the literature, we show that the Bremsstrahlung cross section is not necessarily given by the tree-level annihilation cross section (for a generalized kinematics) times a factor related to the emission of a soft photon. Such a factoriza...

  19. Electron-electron bremsstrahlung emission and the inference of electron flux spectra in solar flares

    OpenAIRE

    Kontar, E. P.; Emslie, A. G.; Massone, A. M.; Piana, M.; Brown, J.C.; Prato, M.

    2007-01-01

    Although both electron-ion and electron-electron bremsstrahlung contribute to the hard X-ray emission from solar flares, the latter is normally ignored. Such an omission is not justified at electron (and photon) energies above $\\sim 300$ keV, and inclusion of the additional electron-electron bremsstrahlung in general makes the electron spectrum required to produce a given hard X-ray spectrum steeper at high energies. Unlike electron-ion bremsstrahlung, electron-electron bremsstrahlung cannot ...

  20. Bremsstrahlung Pair Production In Relativistic Heavy Ion Collision

    OpenAIRE

    Meier, H; Hencken, K.; Trautmann, D.; Baur, G.

    1997-01-01

    We calculate production of electron- and muon-pairs by the bremsstrahlung process in hadron collisions and compare it with the dominant two-photon process. Results for the total cross section are given for proton-proton and heavy-ion collisions at energies of the Relativistic Heavy Ion Collider (RHIC) and the Large Hadron Collider (LHC).

  1. A detector for use in high energy bremsstrahlung shielding studies

    International Nuclear Information System (INIS)

    The design, development and calibration of a detector based on the principle of the Moxon-Rae detector is discussed. It is ideally suited to the measurement of the energy fluence of photons transmitted through a thick shield which has been irradiated with high energy bremsstrahlung. The detection sensitivity is 104 to 105 times that of the P2 ion chamber

  2. Spectra and rates of bremsstrahlung neutrino emission in stars

    CERN Document Server

    Guo, Gang

    2016-01-01

    We calculate the energy-differential rate for neutrino emission from electron-nucleus bremsstrahlung in stellar interiors taking into account the effects of electron screening and ionic correlations. We compare the energy-differential and the net rates, as well as the average $\\bar{\

  3. Constructing the nuclear caloric curve from thermal bremsstrahlung

    NARCIS (Netherlands)

    Ortega, R

    2004-01-01

    The behavior of the emission of thermal bremsstrahlung with the reaction centrality has been studied in Xe-121 + Sn-nat reactions at 50A MeV. A thermal hard photon component is present along the measured impact parameter range (0.1 less than or equal to b/b(max) less than or equal to 0.6) showing th

  4. Infrared phenomena in quantum electrodynamics : II. Bremsstrahlung and compton scattering

    NARCIS (Netherlands)

    Haeringen, W. van

    1960-01-01

    The infrared aspects of quantum electrodynamics are discussed by treating two examples of scattering processes, bremsstrahlung and Compton scattering. As in the previous paper one uses a non-covariant diagram technique which gives very clear insight in the cancelling of infrared divergences between

  5. Feasibility Studies of Exclusive Diffractive Bremsstrahlung Measurement at RHIC Energies

    OpenAIRE

    Chwastowski, Janusz; Cyz, Antoni; Fulek, Łukasz; Kycia, Radosław; Pawlik, Bogdan; Sikora, Rafał; Turnau, Jacek

    2015-01-01

    Feasibility studies of an observation of the exclusive diffractive bremsstrahlung at RHIC at $\\sqrt{s} = 200$~GeV and at $\\sqrt{s} = 500$~GeV are reported. A simplified approach to the photon and the scattered proton energy reconstruction is used. Influence of possible backgrounds is discussed.

  6. Neutrino signals from electroweak bremsstrahlung in solar WIMP annihilation

    Energy Technology Data Exchange (ETDEWEB)

    Bell, Nicole F.; Brennan, Amelia J.; Jacques, Thomas D., E-mail: n.bell@unimelb.edu.au, E-mail: a.brennan@pgrad.unimelb.edu.au, E-mail: thomas.jacques@asu.edu [ARC Centre of Excellence for Particle Physics at the Terascale, School of Physics, The University of Melbourne, Victoria 3010 (Australia)

    2012-10-01

    Bremsstrahlung of W and Z gauge bosons, or photons, can be an important dark matter annihilation channel. In many popular models in which the annihilation to a pair of light fermions is helicity suppressed, these bremsstrahlung processes can lift the suppression and thus become the dominant annihilation channels. The resulting dark matter annihilation products contain a large, energetic, neutrino component. We consider solar WIMP annihilation in the case where electroweak bremsstrahlung dominates, and calculate the resulting neutrino spectra. The flux consists of primary neutrinos produced in processes such as χχ→ν-bar νZ and χχ→ν-bar lW, and secondary neutrinos produced via the decays of gauge bosons and charged leptons. After dealing with the neutrino propagation and flavour evolution in the Sun, we consider the prospects for detection in neutrino experiments on Earth. We compare our signal with that for annihilation to W{sup +}W{sup −}, and show that, for a given annihilation rate, the bremsstrahlung annihilation channel produces a larger signal by a factor of a few.

  7. Exact Bremsstrahlung Function in N=2 Superconformal Field Theories.

    Science.gov (United States)

    Fiol, Bartomeu; Gerchkovitz, Efrat; Komargodski, Zohar

    2016-02-26

    We propose an exact formula for the energy radiated by an accelerating quark in N=2 superconformal theories in four dimensions. This formula reproduces the known bremsstrahlung function for N=4 theories and provides a prediction for all the perturbative and instanton corrections in N=2 theories. We perform a perturbative check of our proposal up to three loops. PMID:26967407

  8. Observation of the Muon Inner Bremsstrahlung at LEP1

    CERN Document Server

    Abdallah, J; Adam, W; Adzic, P; Albrecht, T; Alemany-Fernandez, R; Allmendinger, T; Allport, P P; Amaldi, U; Amapane, N; Amato, S; Anashkin, E; Andreazza, A; Andringa, S; Anjos, N; Antilogus, P; Apel, W D; Arnoud, Y; Ask, S; Åsman, B; Augustin, J E; Augustinus, A; Baillon, P; Ballestrero, A; Bambade, P; Barbier, R; Bardin, D; Barker, G J; Baroncelli, A; Battaglia, M; Baubillier, M; Becks, K H; Begalli, M; Behrmann, A; Ben-Haim, E; Benekos, N; Benvenuti, A; Bérat, C; Berggren, M; Bertrand, D; Besançon, M; Besson, N; Bloch, D; Blom, M; Bluj, M; Bonesini, M; Boonekamp, M; Booth, P S L; Borisov, G; Botner, O; Bouquet, B; Bowcock, T J V; Boyko, I; Bracko, M; Brenner, R; Brodet, E; Brückman, P; Brunet, J M; Buschbeck, B; Buschmann, P; Calvi, M; Camporesi, T; Canale, V; Carena, F; Castro, N; Cavallo, F; Chapkin, M; Charpentier, P; Checchia, P; Chierici, R; Shlyapnikov, P; Chudoba, J; Chung, S U; Cieslik, K; Collins, P; Contri, R; Cosme, G; Cossutti, F; Costa, M J; Crennell, D J; Cuevas-Maestro, J; D'Hondt, J; Da Silva, T; Da Silva, W; Della Ricca, G; De Angelis, A; de Boer, Wim; De Clercq, C; De Lotto, B; De Maria, N; De Min, A; De Paula, L; Di Ciaccio, L; Di Simone, A; Doroba, K; Drees, J; Eigen, G; Ekelöf, T J C; Ellert, M; Elsing, M; Espirito-Santo, M C; Fanourakis, G K; Fassouliotis, D; Feindt, M; Fernández, J; Ferrer, A; Ferro, F; Flagmeyer, U; Föth, H; Fokitis, E; Fulda-Quenzer, F; Fuster, J; Gandelman, M; García, C; Gavillet, P; Gazis, E; Gokieli, R; Golob, B; Gómez-Ceballos, G; Gonçalves, P; Graziani, E; Grosdidier, G; Grzelak, K; Guy, J; Haag, C; Hallgren, A; Hamacher, K; Hamilton, K; Haug, S; Hauler, F; Hedberg, V; Hennecke, M; Herr, H; Hoffman, J; Holmgren, S O; Holt, P J; Houlden, M A; Jackson, J N; Jarlskog, G; Jarry, P; Jeans, D; Johansson, E K; Jonsson, P; Joram, C; Jungermann, L; Kapusta, F; Katsanevas, S; Kokkinias, P; Leinonen, L; Katsoufis, E; Kernel, G; Kersevan, B P; Krumshtein, Z; Lesiak, T; Kerzel, U; Liebig, W; King, B T; Lamsa, J; Liko, D; Kjaer, N J; Leder, G; Kluit, P; Kourkoumelis, C; Leitner, R; Kuznetsov, O; Kucharczyk, M; Ledroit, F; Lopes, J H; Lemonne, J; Lepeltier, V; Lipniacka, A; López, J M; Loukas, D; Lutz, P; Lyons, L; MacNaughton, J; Malek, A; Maltezos, S; Mandl, F; Marco, J; Marco, R; Maréchal, B; Margoni, M; Marin, J C; Mariotti, C; Markou, A; Martínez-Rivero, C; Masik, J; Mastroyiannopoulos, N; Matorras, F; Matteuzzi, C; Mazzucato, F; Mazzucato, M; McNulty, R; Meroni, C; Migliore, E; Mitaroff, W A; Mjörnmark, U; Moa, T; Moch, M; Mönig, K; Monge, R; Montenegro, J; Moraes, D; Moreno, S; Morettini, P; Müller, U; Münich, K; Mulders, M; Mundim, L; Murray, W; Muryn, B; Myatt, G; Myklebust, T; Paganoni, M; Nassiakou, M; Paiano, S; Navarria, F; Nawrocki, K; Nicolaidou, R; Nikolenko, M; Ouraou, A; Parkes, C; Oblakowska-Mucha, A; Oyanguren, A; Obraztsov, V F; Olshevski, A; Palacios, J P; Onofre, A; Palka, H; Orava, R; Österberg, K; Pape, L; Papadopoulou, T D; Parodi, F; Parzefall, U; Passeri, A; Passon, O; Peralta, L; Perepelitsa, V; Perrotta, A; Petrolini, A; Piedra, J; Pieri, L; Pierre, F; Pimenta, M; Piotto, E; Podobnik, T; Poireau, V; Pol, M E; Polok, G; Pozdnyakov, V; Pukhaeva, N; Pullia, A; Rames, J; Read, A; Rebecchi, P; Rehn, J; Reid, D; Reinhardt, R; Renton, P B; Richard, F; Rídky, J; Rivero, M; Rodríguez, D; Romero, A; Ronchese, P; Roudeau, P; Rovelli, T; Ruhlmann-Kleider, V; Ryabtchikov, D; Sadovskii, A; Salmi, L; Salt, J; Sander, C; Savoy-Navarro, A; Schwickerath, U; Sekulin, R; Siebel, M; Sisakian, A; Smadja, G; Smirnova, O; Sokolov, A; Sopczak, A; Sosnowski, R; Spassoff, Tz; Stanitzki, M; Stocchi, A; Strauss, J; Stugu, B; Szczekowski, M; Szeptycka, M; Szumlak, T; Tabarelli de Fatis, T; Tegenfeldt, F; Timmermans, J; Tkatchev, L; Tobin, M; Todorovova, S; Tomé, B; Tonazzo, A; Tortosa, P; Travnicek, P; Treille, D; Tristram, G; Trochimczuk, M; Troncon, C; Turluer, M L; Tyapkin, I A; Tyapkin, P; Tzamarias, S; Uvarov, V; Valenti, G; van Dam, P; Van Eldik, J; Van Remortel, N; Van Vulpen, I; Vegni, G; Veloso, F; Venus, W; Verdier, P; Verzi, V; Vilanova, D; Vitale, L; Vrba, V; Wahlen, H; Washbrook, A J; Weiser, C; Wicke, D; Wickens, J; Wilkinson, G; Winter, M; Witek, M; Yushchenko, O; Zalewska-Bak, A; Zalewski, P; Zavrtanik, D; Zhuravlov, V; Zimin, N I; Zintchenko, A; Zupan, M

    2008-01-01

    Muon bremsstrahlung photons converted in front of the DELPHI main tracker (TPC) in dimuon events at LEP1 were studied in two photon kinematic ranges: 0.2 < E_gamma <= 1 GeV and transverse momentum with respect to the parent muon p_T < 40 MeV/c, and 1 < E_gamma <= 10 GeV and p_T < 80 MeV/c . A good agreement of the observed photon rate with predictions from QED for the muon inner bremsstrahlung was found, contrary to the anomalous soft photon excess that has been observed recently in hadronic Z^0 decays. The obtained ratios of the observed signal to the predicted level of the muon bremsstrahlung are 1.06 +/- 0.12 +/- 0.07 in the photon energy range 0.2 < E_gamma <= 1 GeV and 1.04 +/- 0.09 +/- 0.12 in the photon energy range 1 < E_gamma <= 10 GeV. The bremsstrahlung dead cone is observed for the first time in the direct photon production at LEP.

  9. Initial studies of Bremsstrahlung energy deposition in small-bore superconducting undulator structures in linac environments

    Energy Technology Data Exchange (ETDEWEB)

    Cremer, T.; Tatchyn, R. [Stanford Univ., CA (United States)

    1995-12-31

    One of the more promising technologies for developing minimal-length insertion devices for linac-driven, single-pass Free Electron Lasers (FELs) operating in the x-ray range is based on the use of superconducting (SC) materials. In recent FEL simulations, for example, a bifilar helical SC device with a 2 cm period and 1.8 T field was found to require a 30 m saturation length for operation at 1.5{Angstrom} on a 15 GeV linac, more than 40% shorter than an alternative hybrid/permanent magnet (hybrid/PM) undulator. AT the same time, however, SC technology is known to present characteristic difficulties for insertion device design, both in engineering detail and in operation. Perhaps the most critical problem, as observed, e.g., by Madey and co-workers in their initial FEL experiments, was the frequent quenching induced by scattered electrons upstream of their (bifilar) device. Postulating that this quenching was precipitated by directly-scattered or bremsstrahlung-induced particle energy deposited into the SC material or into material contiguous with it, the importance of numerical and experimental characterizations of this phenomenon for linac-based, user-facility SC undulator design becomes evident. In this paper we discuss selected prior experimental results and report on initial EGS4 code studies of scattered and bremsstrahlung induced particle energy deposition into SC structures with geometries comparable to a small-bore bifilar helical undulator.

  10. SU-E-E-08: Applications of the Quantization of Coupled Circuits in Radiation Physics (design of Klystron, Bremsstrahlung, Synchrotron)

    International Nuclear Information System (INIS)

    Purpose: During the past decade the quantization of coupled/forced electromagnetic circuits with or without Ohm’s resistance has gained the subject of some fundamental studies, since even problems of quantum electrodynamics can be solved in an elegant manner, e.g. the creation of quantized electromagnetic fields. In this communication, we shall use these principles to describe optimization procedures in the design of klystrons, synchrotron irradiation and high energy bremsstrahlung. Methods: The base is the Hamiltonian of an electromagnetic circuit and the extension to coupled circuits, which allow the study of symmetries and perturbed symmetries in a very apparent way (SU2, SU3, SU4). The introduction resistance and forced oscillators for the emission and absorption in such coupled systems provides characteristic resonance conditions, and atomic orbitals can be described by that. The extension to virtual orbitals leads to creation of bremsstrahlung, if the incident electron (velocity v nearly c) is described by a current, which is associated with its inductivitance and the virtual orbital to the charge distribution (capacitance). Coupled systems with forced oscillators can be used to amplify drastically the resonance frequencies to describe klystrons and synchrotron radiation. Results: The cross-section formula for bremsstrahlung given by the propagator method of Feynman can readily be derived. The design of klystrons and synchrotrons inclusive the radiation outcome can be described and optimized by the determination of the mutual magnetic couplings between the oscillators induced by the currents. Conclusions: The presented methods of quantization of circuits inclusive resistance provide rather a straightforward way to understand complex technical processes such as creation of bremsstrahlung or creation of radiation by klystrons and synchrotrons. They can either be used for optimization procedures and, last but not least, for pedagogical purposes with regard to

  11. Reconstruction of 12 MV bremsstrahlung spectra from measured transmission data

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    Transmission data for 12 MV bremsstrahlung beams produced by the process for continuous-pulsed 12 MV electrons coming from a linear accelerator hitting a 1.2mm thick plane tantalum target have been acquired with a combination of iron and Telfon attenuators. Two solid state dosimeters with LiF-TLD material surrounded Telfon were used as detectors. It has been checked that the experimental system achieves reasonably narrow-beam geometry by Monte Carlo simulations. From these transmission data, the original energy photon spectrum has been reconstructed using the iterative least-squares technique and compared with the spectrum calculated with Monte Carlo code system EGSnrc. The comparison shows that the numerical technique for analysis of transmission data can represent 12 MV bremsstrahlung spectrum acceptably well. The purpose of our work is to provide an effective way to reconstruct an unknown photon spectrum with high energy component and prove the correctness of this way.

  12. Bremsstrahlung during $\\alpha$-decay: quantum multipolar model

    CERN Document Server

    Maydanyuk, Sergei P

    2008-01-01

    In this paper the improved multipolar model of bremsstrahlung accompanied the $\\alpha$-decay is presented. The angular formalism of calculations of the matrix elements, being enough complicated component of the model, is stated in details. A new definition of the angular (differential) probability of the photon emission in the $\\alpha$-decay is proposed where direction of motion of the $\\alpha$-particle outside (with its tunneling inside barrier) is defined on the basis of angular distribution of its spacial wave function. In such approach, the model gives values of the angular probability of the photons emission in absolute scale, without its normalization on experimental data. Effectiveness of the proposed definition and accuracy of the spectra calculations of the bremsstrahlung spectra are analyzed in their comparison with experimental data for the $^{210}{\\rm Po}$, $^{214}{\\rm Po}$, $^{226}{\\rm Ra}$ and $^{244}{\\rm Cm}$ nuclei, and for some other nuclei predictions are performed (in absolute scale). With ...

  13. Axial coherent bremsstrahlung of type A in a diamond crystal

    International Nuclear Information System (INIS)

    Axial coherent bremsstrahlung of type A (ACBA) has not been intensively investigated either theoretically or experimentally. Making use of the many-beam (two-dimensional quantum treatment) formalism for transversely bound electrons moving through crystal lattices, we have computed ACBA spectra for 17 MeV electrons passing through a 10 μm thick diamond (C) crystal. We found that the momentum transfer occurs in the plane perpendicular to the axis of interest. Only momentum transfers along the scan direction (electron transverse momentum direction) result in a photon emission in the forward direction. Two different scans have shown that the energies of the coherent bremsstrahlung peaks depend strongly on the direction of the electron transverse momentum. We also present a comparison of the first order Born approximation and the many-beam formalism

  14. The LPM effect in sequential bremsstrahlung: 4-gluon vertices

    CERN Document Server

    Arnold, Peter; Iqbal, Shahin

    2016-01-01

    The splitting processes of bremsstrahlung and pair production in a medium are coherent over large distances in the very high energy limit, which leads to a suppression known as the Landau-Pomeranchuk-Migdal (LPM) effect. In this paper, we continue study of the case when the coherence lengths of two consecutive splitting processes overlap (which is important for understanding corrections to standard treatments of the LPM effect in QCD), avoiding soft-gluon approximations. In particular, this paper completes the calculation of the rate for real double gluon bremsstrahlung from an initial gluon with various simplifying assumptions (thick media; $\\hat q$ approximation; and large $N_c$) by now including processes involving 4-gluon vertices.

  15. Cross sections for bremsstrahlung production and electron-impact ionization

    International Nuclear Information System (INIS)

    Electron transport codes require extensive information on the cross sections that govern electron interactions with the atoms that make up the medium. These processes include bremsstrahlung production in the atomic field, excitation and ionization of atomic electrons, and elastic scattering by screened atomic nuclei. These fundamental processes are of basic interest in many fields, but their inclusion in general purpose Monte Carlo transport codes imposes the requirement that reasonably accurate cross-section data be available over a very wide range of energies and for virtually any material. In this chapter, the author discusses two of these processes: bremsstrahlung production and electron-impact ionization. Both of these interactions result in the production of secondary radiations that can be important in radiation transport calculations

  16. Feasibility studies of the diffractive bremsstrahlung measurement at the LHC

    Energy Technology Data Exchange (ETDEWEB)

    Chwastowski, Janusz J.; Czekierda, Sabina; Staszewski, Rafal; Turnau, Jacek; Trzebinski, Maciej [The Henryk Niewodniczanski Institute of Nuclear Physics, Polish Academy of Sciences, Cracow (Poland); Kycia, Radoslaw [Cracow University of Technology, Faculty of Physics, Mathematics and Computer Science, Cracow (Poland)

    2016-06-15

    Feasibility studies of an observation of the exclusive diffractive bremsstrahlung in proton-proton scattering at the centre of mass energy 13 TeV at the LHC are reported. These studies aim at the dedicated data taking periods with low instantaneous luminosity delivered by the LHC where the pile-up interactions can be neglected. A simplified approach to the photon and the scattered proton energy reconstruction is used. The background influence is discussed. (orig.)

  17. Bremsstrahlung of Fast Charged Particles on Clusters in a Wide Spectral Range

    International Nuclear Information System (INIS)

    Within the framework of the first Born approximation and a simple model of the structural factor, the bremsstrahlung of fast charged particles on polyatomic clusters is calculated and analyzed with regard to the polarization mechanism in a wide spectral range including a domain of high frequencies. The role of cooperative phenomena in the static and polarization channels of bremsstrahlung is investigated. It is established that these phenomena, being negligible for static bremsstrahlung, substantially influence the polarization bremsstrahlung. It is shown that the constructive interference between the contributions of the atoms of a cluster to the polarization bremsstrahlung substantially increases its intensity and changes its dependence on the basic parameters of the problem compared with the case of bremsstrahlung on an isolated atom

  18. Bremsstrahlung of fast charged particles when scattering on clusters in wide spectral range

    International Nuclear Information System (INIS)

    Within the framework of the first Born approximation and a simple model of the structural factor, the bremsstrahlung of fast charged particles on polyatomic clusters is calculated and analyzed with regard to the polarization mechanism in a wide spectral range including a domain of high frequencies. The role of cooperative phenomena in the static and polarization channels of bremsstrahlung is investigated. It is established that these phenomena, being negligible for static bremsstrahlung, substantially influence the polarization bremsstrahlung. It is shown that the constructive interference between the contributions of the atoms of a cluster to the polarization bremsstrahlung substantially increases its intensity and changes its dependence on the basic parameters of the problem compared with the case of bremsstrahlung on an isolated atom

  19. Usefulness of Bremsstrahlung Images after Intra arterial Y 90 Resin Microphere Radioembolization for Hepatic Tumors

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Young Chul; Kim, Wun Hwan; Um, Soon Ho; Seo, Yeon Seok; Park, Eun Kyung; Oh, Sun Young; Han, You Mie [Korea Univ. Anam Hospital, Seoul (Korea, Republic of); Choe, Jae Gol [Hallym Univ. Hangang Secred Heart Hospital, Seoul (Korea, Republic of)

    2011-03-15

    Y 90 resin microsphere radioembolization is used to treat inoperable hepatic tumors. After injection of Y 90 resin microsphere, the only method to visualize the distribution of Y 90 is the scintigraphic imaging of bremsstrahlung radiation. The purpose of this study was to evaluate the characteristics and usefulness of bremsstrahlung imaging in Y 90 resin microsphere treatment. Twenty patients (22 administrations) underwent intra arterial Y 90 resin microsphere treatment. For pretreatment planning, images of Tc 99m albumin macroag gregate (MAA) arterial injection and hepatic contrast angiography were obtained. Post treatment bremsstrahlung images were taken and compared with pre treatment images. The extrahepatic activity was evaluated on bremsstrahlung images. To correlate the size and vascularity of the tumors with tumor visualization on bremsstrahlung images, the individual tumors were grouped according to visualization on each image and compared with one another by size and tumor to normal ratio. All post therapeutic bremsstrahlung images showed similar contours of the liver with pre treatment angiography. No extrahepatic activity was seen in all cases. The visualized tumors on bremsstrahlung images were significantly larger than the non visualized tumors on bremsstrahlung images were significantly higher than those of the non visualized tumors. Bremsstrahlung images after intra arterial Y 90 resin microsphere treatment are useful in evaluating the intrahepatic distribution of radioisotope and detecting possible extrahepatic activity.

  20. Internal bremsstrahlung signatures in light of direct dark matter searches

    Energy Technology Data Exchange (ETDEWEB)

    Garny, Mathias [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Ibarra, Alejandro; Pato, Miguel; Vogl, Stefan [Technische Univ. Muenchen, Garching (Germany). Physik Dept. T30d

    2013-06-15

    Although proposed long ago, the search for internal bremsstrahlung signatures has only recently been made possible by the excellent energy resolution of ground-based and satellite-borne gamma-ray instruments. Here, we investigate thoroughly the current status of internal bremsstrahlung searches in light of the results of direct dark matter searches and in the framework of minimal mass-degenerate scenarios. The constraints set by Fermi-LAT and H.E.S.S. extend uninterrupted from tens of GeV up to tens of TeV and are rather insensitive to the mass degeneracy in the particle physics model. In contrast, direct searches are best in the moderate to low mass splitting regime, where XENON100 limits overshadow Fermi-LAT and H.E.S.S. up to TeV masses if dark matter couples to (light) quarks. We examine carefully the prospects for GAMMA-400, CTA and XENON1T, all planned to come online in the near future, and find that: (a) CTA and XENON1T are fully complementary, with CTA most sensitive to multi-TeV masses and mass splittings around 10%, and XENON1T probing best small mass splittings up to TeV masses; and (b) current constraints from XENON100 already preclude the observation of any spectral feature with GAMMA-400 in spite of its impressive energy resolution, unless dark matter does not couple to light quarks. Finally, we point out that, unlike for direct searches, the possibility of detecting thermal relics in upcoming internal bremsstrahlung searches requires boost factors larger than {proportional_to}10.

  1. Angular Distribution of Photons in Coherent Bremsstrahlung in Deformed Crystals

    CERN Document Server

    Parazian, V V

    2010-01-01

    We investigate the angular distribution of photons in the coherent bremsstrahlung process by high-energy electrons in a periodically deformed single crystal with a complex base. The formula for the corresponding differential cross-section is derived for an arbitrary deformation field. The case is considered in detail when the electron enters into the crystal at small angles with respect to a crystallographic axis. The results of the numerical calculations are presented for SiO2 single crystal and Moliere parameterization of the screened atomic potentials in the case of the deformation field generated by the acoustic wave of S -type.

  2. Formation of bremsstrahlung in an absorptive QED/QCD medium

    OpenAIRE

    Bluhm, Marcus; Gossiaux, Pol Bernard; Gousset, Thierry; Aichelin, Joerg

    2012-01-01

    The radiative energy loss of a relativistic charge in a dense, absorptive medium can be affected significantly by damping phenomena. The effect is more pronounced for large energies of the charge and/or large damping of the radiation. This can be understood in terms of a competition between the formation time of bremsstrahlung and a damping time scale. We discuss this competition in detail for the absorptive QED and QCD medium, focusing on the case in which the mass of the charge is large com...

  3. Generation of Long-Lived Isomeric States via Bremsstrahlung Irradiation

    CERN Document Server

    Cheng, Y; Tang, C; Liu, Y; Jin, Q; Cheng, Yao; Xia, Bing; Tang, Chuanxiang; Liu, Yinong; Jin, Qingxiu

    2006-01-01

    A method to generate long-lived isomeric states effectively for Mossbauer applications is reported. We demonstrate that this method is better and easier to provide highly sensitive Mossbauer effect of long-lived isomers (>1ms) such as 103Rh. Excitation of (gamma,gamma) process by synchrotron radiation is painful due mainly to their limited linewidth. Instead,(gamma,gamma') process of bremsstrahlung excitation is applied to create these long-lived isomers. Isomers of 45Sc, 107Ag, 109Ag, and 103Rh have been generated from this method. Among them, 103Rh is the only one that we have obtained the gravitational effect at room temperature.

  4. Diffraction structures in high-energy electron–nucleus bremsstrahlung

    Energy Technology Data Exchange (ETDEWEB)

    Jakubassa-Amundsen, D.H.

    2013-10-30

    The emission of hard bremsstrahlung during the collision of relativistic spin-polarized electrons with inert spin 0 and spin 1/2 nuclei is calculated within the weak-potential approximation. Diffraction structures in the polarization correlations between the beam electron and the emitted photon are predicted for collision energies in the region 50–120 MeV if the photon is emitted at backward angles. The dynamical recoil plays a dominant role concerning the location and the shape of the structures. The target nuclei {sup 19}F, {sup 64}Zn and {sup 89}Y are investigated.

  5. Molecular bremsstrahlung radiation at GHz frequencies in air

    Science.gov (United States)

    Al Samarai, Imen; Bérat, Corinne; Deligny, Olivier; Letessier-Selvon, Antoine; Montanet, François; Settimo, Mariangela; Stassi, Patrick

    2016-03-01

    A detection technique for ultra-high-energy cosmic rays, complementary to the fluorescence technique, would be the use of the molecular bremsstrahlung radiation emitted by low-energy ionization electrons left after the passage of the showers in the atmosphere. In this article, a detailed estimate of the spectral intensity of photons at ground level originating from this radiation is presented. The spectral intensity expected from the passage of the high-energy electrons of the cascade is also estimated. The absorption of the photons in the plasma of electrons and neutral molecules is shown to be negligible. The obtained spectral intensity is shown to be 2 ×1 0-21 W cm-2 GHz-1 at 10 km from the shower core for a vertical shower induced by a proton of 1 017.5 eV . In addition, a recent measurement of bremsstrahlung radiation in air at gigahertz frequencies from a beam of electrons produced at 95 keV by an electron gun is also discussed and reasonably reproduced by the model.

  6. Molecular Bremsstrahlung Radiation at GHz Frequencies in Air

    CERN Document Server

    Samarai, I Al; Deligny, O; Letessier-Selvon, A; Montanet, F; Settimo, M; Stassi, P

    2016-01-01

    A detection technique for ultra-high energy cosmic rays, complementary to the fluorescence technique, would be the use of the molecular Bremsstrahlung radiation emitted by low-energy ionization electrons left after the passage of the showers in the atmosphere. In this article, a detailed estimate of the spectral intensity of photons at ground level originating from this radiation is presented. The spectral intensity expected from the passage of the high-energy electrons of the cascade is also estimated. The absorption of the photons in the plasma of electrons/neutral molecules is shown to be negligible. The obtained spectral intensity is shown to be $2\\times10^{-21} $W cm$^{-2}$ GHz$^{-1}$ at 10 km from the shower core for a vertical shower induced by a proton of $10^{17.5}$ eV. In addition, a recent measurement of Bremsstrahlung radiation in air at gigahertz frequencies from a beam of electrons produced at 95 keV by an electron gun is also discussed and reasonably reproduced by the model.

  7. Measurement of absorbed dose by 7-GeV bremsstrahlung in a PMMA phantom

    CERN Document Server

    Job, P K; Semones, E

    1999-01-01

    High-energy electron storage rings generate energetic bremsstrahlung photons through radiative interaction of the particle beam with the residual gas molecules and other components inside the storage ring. At synchrotron radiation facilities, where beamlines are channeled out of the storage ring, a continuous bremsstrahlung spectrum, with a maximum energy of the stored particle beam, will be present. At the advanced photon source (APS), where the stored beam energy is 7 GeV, bremsstrahlung generated in the straight sections of the insertion device beamlines, which are a total of 15.38 m in length, can be significant. The contribution from each bremsstrahlung interaction adds up to produce a narrow mono-directional bremsstrahlung beam that comes down through the insertion device beamlines. The resulting absorbed dose distributions by this radiation in a 300 mmx300 mmx300 mm tissue substitute cube phantom were measured with LiF:Mg,Ti (TLD-700) thermoluminescent dosemeters. The normalized absorbed dose, in a cro...

  8. Search of gamma-rays Bremsstrahlung mirror reflection

    International Nuclear Information System (INIS)

    Full text: Total external reflection of soft X-rays is widely used in many X-ray optic systems. At the same time in the wavelength range of gamma rays the corresponding total external reflection on macroscopic smooth surface hasn't been surely verified yet. Samarkand microtron MT-22S with 330 meter flying distance was used for a search experiment of detecting gamma-ray total external reflection. Measured slip angles (i.e. angles between incident ray and reflector surface) are negligible and don't exceed tens of micro-radian. And it is a complicated problem to get required characteristics of collimating, reflecting and detecting gamma rays. The experimental setup was described earlier. Here we report experimental results of very small-angle Bremsstrahlung scattering only in comparison with results of computer simulation by Monte-Carlo method. It is continuous energy spectrum of Bremsstrahlung gamma rays (described by Shift formula) that is the first characteristic property of the experiment. And it is air in the way of gamma rays that is the second one. Continuous energy spectrum provides a use of some range of reflector inclinations (but bounded above) that satisfy the conditions of the total reflection for a corresponding part of gamma ray beam. As for air it absorbs gamma rays on their long way to detectors lowering the ratio of searching effect to background. Horizontal belt type Bremsstrahlung beam was collimated for the experiment. So the beam's horizontal acceptance was relatively wide (∼ 34 mrad). A collimator with gap heights of 100, 50 and 20 μ limited the beam in vertical that results in beam vertical divergences of 125, 62 and 25 μrad, correspondingly. The gap height of 100 μ used for positioning procedure, and the ones of 50 and 20 μ used for measurements. No separate peak of reflected gamma rays was observed at the experiment. However when vertical profiles measured at the reflector inclinations of 0 and 40 μrad are compared one can see gamma

  9. The LPM effect in sequential bremsstrahlung: dimensional regularization

    CERN Document Server

    Arnold, Peter; Iqbal, Shahin

    2016-01-01

    The splitting processes of bremsstrahlung and pair production in a medium are coherent over large distances in the very high energy limit, which leads to a suppression known as the Landau-Pomeranchuk-Migdal (LPM) effect. Of recent interest is the case when the coherence lengths of two consecutive splitting processes overlap (which is important for understanding corrections to standard treatments of the LPM effect in QCD). In previous papers, we have developed methods for computing such corrections without making soft-gluon approximations. However, our methods require consistent treatment of canceling ultraviolet (UV) divergences associated with coincident emission times, even for processes with tree-level amplitudes. In this paper, we show how to use dimensional regularization to properly handle the UV contributions. We also present a simple diagnostic test that any consistent UV regularization method for this problem needs to pass.

  10. Spectra and rates of bremsstrahlung neutrino emission in stars

    Science.gov (United States)

    Guo, Gang; Qian, Yong-Zhong

    2016-08-01

    We calculate the energy-differential rate for neutrino emission from electron-nucleus bremsstrahlung in stellar interiors taking into account the effects of electron screening and ionic correlations. We compare the energy-differential and the net rates, as well as the average ν¯e and ν¯x(x =μ ,τ ) energies, for this process with those for e± pair annihilation, plasmon decay, and photoneutrino emission over a wide range of temperature and density. We also compare our updated energy loss rates for the above thermal neutrino emission processes with the fitting formulas widely used in stellar evolution models and determine the temperature and density domain in which each process dominates. We discuss the implications of our results for detection of ν¯e from massive stars during their presupernova evolution and find that pair annihilation makes the predominant contribution to the signal from the thermal emission processes.

  11. Vacuum Cherenkov radiation and bremsstrahlung from disformal couplings

    Science.gov (United States)

    van de Bruck, Carsten; Burrage, Clare; Morrice, Jack

    2016-08-01

    The simplest way to modify gravity is to extend the gravitational sector to include an additional scalar degree of freedom. The most general metric that can be built in such a theory includes disformal terms, so that standard model fields move on a metric which is the sum of the space time metric and a tensor constructed from first derivatives of the scalar. In such a theory gravitational waves and photons can propagate at different speeds, and these can in turn be different from the maximum speed limit for matter particles. In this work we show that disformal couplings can cause charged particles to emit Cherenkov radiation and bremsstrahlung apparently in vacuum, depending on the background evolution of the scalar field. We discuss the implications of this for observations of cosmic rays, and the constraints that arise for models of dark energy with disformal couplings.

  12. Vacuum Cherenkov radiation and bremsstrahlung from disformal couplings

    CERN Document Server

    van de Bruck, Carsten; Morrice, Jack

    2016-01-01

    The simplest way to modify gravity is to extend the gravitational sector to include an additional scalar degree of freedom. The most general metric that can be built in such a theory includes disformal terms, so that standard model fields move on a metric which is the sum of the space time metric and a tensor constructed from first derivatives of the scalar. In such a theory gravitational waves and photons can propagate at different speeds, and these can in turn be different from the maximum speed limit for matter particles. In this work we show that disformal couplings can cause charged particles to emit Cherenkov radiation and bremsstrahlung apparently in vacuum, depending on the background evolution of the scalar field. We discuss the implications of this for observations of cosmic rays, and the constraints that arise for models of dark energy with disformal couplings.

  13. Internal bremsstrahlung endpoint energy of {sup 54}Mn

    Energy Technology Data Exchange (ETDEWEB)

    Hindi, M. M. [Physics Department, Tennessee Technological University, Cookeville, Tennessee 38505 (United States); Larimer, R.-M. [Nuclear Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Norman, E. B. [Nuclear Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Rech, G. A. [Nuclear Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States)

    2000-05-01

    For {sup 54}Mn there is a discrepancy between the Q{sub EC} obtained from the endpoint energy of the internal bremsstrahlung (IB) spectrum which accompanies the electron capture decay (Q{sub EC}=1353{+-}8 keV) and that obtained from the accepted mass differences (Q{sub EC}=1377{+-}1 keV). This Q value is needed to deduce the partial-half life of the astrophysically interesting {beta}{sup -} decay of {sup 54}Mn from the recently measured {beta}{sup +} partial half-life. To resolve this discrepancy, we have remeasured the endpoint energy of the IB spectrum, by recording coincidences between the IB and the 835-keV {gamma} ray, both detected in Compton-suppressed Ge detectors. The Q{sub EC} we deduce is 1379{+-}8 keV, in agreement with the accepted mass differences. (c) 2000 The American Physical Society.

  14. 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.

  15. Nucleon-Nucleon Bremsstrahlung emission of massive Axion

    CERN Document Server

    Giannotti, M

    2005-01-01

    We consider the problem of axion production by bremsstrahlung emission in a nuclear medium. The usual assumption of a massless axion is replaced by more general hypotheses, so that we can describe the emission process for axions with mass up to a few MeV. We point out that in certain physical situations the contribution from non-zero mass is non-negligible. In particular, in the mechanism for the production of Gamma Ray Bursts via emission of heavy axions the axion mass m_a ~ 1MeV is comparable with the temperature of the nuclear medium and thus can not be disregarded. Looking at our results we find, in fact, a fairly considerable reduction of the axion luminosity in that mechanism.

  16. The double copy: Bremsstrahlung and accelerating black holes

    CERN Document Server

    Luna, Andres; Nicholson, Isobel; O'Connell, Donal; White, Chris D

    2016-01-01

    Advances in our understanding of perturbation theory suggest the existence of a correspondence between classical general relativity and Yang-Mills theory. A concrete example of this correspondence, which is known as the double copy, was recently introduced for the case of stationary Kerr-Schild spacetimes. Building on this foundation, we examine the simple time-dependent case of an accelerating, radiating point source. The gravitational solution, which generalises the Schwarzschild solution, includes a non-trivial stress-energy tensor. This stress-energy tensor corresponds to a gauge theoretic current in the double copy. We interpret both of these sources as representing the radiative part of the field. Furthermore, in the simple example of Bremsstrahlung, we determine a scattering amplitude describing the radiation, maintaining the double copy throughout. Our results provide the strongest evidence yet that the classical double copy is directly related to the BCJ double copy for scattering amplitudes.

  17. The double copy: Bremsstrahlung and accelerating black holes

    Science.gov (United States)

    Luna, Andrés; Monteiro, Ricardo; Nicholso, Isobel; O'Connell, Donal; White, Chris D.

    2016-06-01

    Advances in our understanding of perturbation theory suggest the existence of a correspondence between classical general relativity and Yang-Mills theory. A concrete example of this correspondence, which is known as the double copy, was recently intro-duced for the case of stationary Kerr-Schild spacetimes. Building on this foundation, we examine the simple time-dependent case of an accelerating, radiating point source. The gravitational solution, which generalises the Schwarzschild solution, includes a non-trivial stress-energy tensor. This stress-energy tensor corresponds to a gauge theoretic current in the double copy. We interpret both of these sources as representing the radiative part of the field. Furthermore, in the simple example of Bremsstrahlung, we determine a scattering amplitude describing the radiation, maintaining the double copy throughout. Our results provide the strongest evidence yet that the classical double copy is directly related to the BCJ double copy for scattering amplitudes.

  18. Vircator in regime of x-ray Bremsstrahlung

    International Nuclear Information System (INIS)

    The power vircator with multi-flight electrons cross optical thin anode foil power pulses generation of X-ray radiation created and operated in first. The vircator realized on the base of direct action electron accelerator with supplies of inductive energy storage with plasma switch of current. In paper results of 2-D self-consistent calculations of electron beam dynamics in vircator camera and determined spectra of arise UHF-radiation. The results of first experiments on vircator X-ray Bremsstrahlung for thin (10 mkm, Ta) and thick (100 mkm, Ta) anode foils are presented. The dose of X-ray radiation for thin foil (Eγ > 30 keV) in 8 greater than dose received for thick anode, middle photon energy reduced from 80 keV to 30 keV

  19. Rhodium M(o)ssbauer Effect Generated by Bremsstrahlung Excitation

    Institute of Scientific and Technical Information of China (English)

    CHENG Yao; XIA Bing; LIU Yi-Nong; JIN Qing-Xiu

    2005-01-01

    @@ A method for effectively generating long-lived Mossbauer photons and methods for proving the associated Mossbauer effects are reported. For the first time, we observed resonant propagation and resonant absorption of 40-keV Mossbauer photons emitted from 103Rh through (γ,γ′) process excited by bremsstrahlung. This is a new efficient way to generate long-lived isomer (> 1 ms) for Mossbauer spectroscopy with sufficient brilliance.An abnormally large ratio of resonant absorption between horizontal and vertical directions indicates horizontal trapping of Mossbauer photons and anisotropic Mossbauer emission, which can be attributed to gravitational effect on the 103Rh Mossbauer isomer with extremely narrow 10-19 eV linewidth.

  20. The influence of Bremsstrahlung induced photoionization for the streamer motion in various gas mixtures

    Science.gov (United States)

    Koehn, Christoph; Chanrion, Olivier; Neubert, Torsten

    2016-04-01

    Streamers, the beginning stages of electric discharges, evolve differently depending on their polarity and on the ambient gas composition. One of the well-known supporting mechanisms is "UVphotoionization" where, in air, excited nitrogen emits a UV photon subsequently ionizing oxygen. In pure nitrogen, however, this mechanism is suppressed because of the lack of oxygen; hence this mechanism strongly depends on the ambient gas medium. In this paper we introduce Bremsstrahlung induced photoionization: In the ambient electric field,electrons gain energy and produce Bremsstrahlung photons through the collision with the ambient gas molecules; similarly to "UV-photoionization", the Bremsstrahlung photons ionize the gas molecules and, as such, create electron populations detached from the initial electron patch. For the study of this process we implemented the electron-nucleus Bremsstrahlung process as well as the photoionization by individual photons into an already existing 2.5 D Monte Carlo particle code for the simulation of streamers. We initiated plasma patches of electrons and ions with varying initial electron energies and peak densities in different ambient fields in air and pure nitrogen. We will compare the temporal evolution of the electron densities as well as of the electric field with and without modelling Bremsstrahlung. In air we will test the influence of Bremsstrahlung induced photoionization against "UV-photoionization". We will show that the influence of Bremsstrahlung is negligible in air, but plays a significant role in pure nitrogen at standard temperature and pressure.

  1. Study of compound nucleus formation via bremsstrahlung emission in proton $\\alpha$-particle scattering

    CERN Document Server

    Maydanyuk, Sergei P

    2016-01-01

    In this paper a role of many-nucleon dynamics in formation of the compound $^{5}{\\rm Li}$ nucleus in the scattering of protons off $\\alpha$-particles at the proton incident energies up to 20 MeV is investigated. We propose a bremsstrahlung model allowing to extract information about probabilities of formation of such nucleus on the basis of analysis of experimental cross-sections of the bremsstrahlung photons. In order to realize this approach, the model includes elements of microscopic theory and also probabilities of formation of the short-lived compound nucleus. Results of calculations of the bremsstrahlung spectra are in good agreement with the experimental cross-sections.

  2. Electron spectroscopy in the fundamental process of electron-nucleus bremsstrahlung

    International Nuclear Information System (INIS)

    Within the scope of this thesis the fundamental process of electron-nucleus bremsstrahlung was studied in inverse kinematics at the Experimental Storage Ring ESR at GSI. For the system U88+ + N2 at 90 MeV/u it was shown, that by using inverse kinematics coincidence measurements between the scattered electron and the emitted photon can be performed for the case, in which the incoming electron transfers almost all of its kinetic energy onto the emitted photon. The sensitivity to the fundamental process could be achieved by measuring triple differential cross sections as a function of the emission angle of the photon and the scattered electron as well as the energy of the scattered electron. The optics of the magnetic electron spectrometer used were thoroughly revised and optimized to the experimental requirements. Analyzing different coincidences in this collision system, it was possible to determine the contributions to the electron distribution arising from radiative electron capture to the projectile continuum, nonradiative electron capture to the projectile continuum, and electron loss to the projectile continuum. The experimental results of each of these processes were compared to theoretical calculations. The electron spectra for the radiative and the nonradiative electron capture to continuum clearly reproduce the opposite asymmetry predicted by theory. Furthermore electron spectra for collisions of U28+ with different gases were measured.

  3. The bremsstrahlung tagged photon beam in Hall B at the Jefferson Laboratory

    International Nuclear Information System (INIS)

    We describe the design and commissioning of the photon tagging beamline installed in experimental Hall B at the Thomas Jefferson National Accelerator Facility (Jlab). This system can tag photon energies over a range from 20% to 95% of the incident electron energy, and is capable of operation with beam energies up to 6.1 GeV. A single dipole magnet is combined with a hodoscope containing two planar arrays of plastic scintillators to detect energy-degraded electrons from a thin bremsstrahlung radiator. The first layer of 384 partially overlapping small scintillators provides photon energy resolution, while the second layer of 61 larger scintillators provides the timing resolution necessary to form a coincidence with the corresponding nuclear interaction triggered by the tagged photon. The definitions of overlap channels in the first counter plane and of geometric correlation between the two planes are determined using digitized time information from the individual counters. Auxiliary beamline devices are briefly described, and performance results to date under real operating conditions are presented. The entire photon-tagging system has met or exceeded its design goals

  4. Calculation of beta induced Bremsstrahlung exposure from therapeutic radionuclide 198Au in tissues, DNA and RNA

    International Nuclear Information System (INIS)

    Gold-198 (βmax= 0.96 MeV (98.6%), γmax= 0.412 MeV (95.5%) and T1/2 = 2.7 days) is a well-known therapeutic beta emitter in the field of nuclear medicine, and is being used for the treatment of many different cancers. In the present study, the Bremsstrahlung exposure induced by 198Au in different human tissues, DNA and RNA has been calculated. The specific Bremsstrahlung constant (ΓBr), Probability of energy loss by beta during Bremsstrahlung emission (PBr) and Bremsstrahlung activity (Arelease)Br were estimated. We strongly recommend these parameters should be considered in absorbed dose calculations of radionuclide therapy via 198Au. (orig.)

  5. Effects of electron temperature and density on ion-dust bremsstrahlung

    OpenAIRE

    Jung, Young-Dae; MURAKAMI, Izumi

    2009-01-01

    The effects of electron temperature and density on the ion-dust grain bremsstrahlung process industy plasmas are studied. The ion-dust bremsstrahlung radiation cross section is obtained as afunction of the dust charge, dust radius, Debye length, collision energy, radiation energy, electrondensity, and electron temperature by using the Born approximation. It is shown that the ion-dustbremsstrahlung radiation cross section decreases with an increase in the electron density in dustyplasmas. It i...

  6. Energy spectra of secondary neutrons produced by high energy bremsstrahlung in carbon, nitrogen, oxygen and tissue

    International Nuclear Information System (INIS)

    Neutron energy spectra in carbon, nitrogen and oxygen were calculated for various bremsstrahlung end-point energies and, from these, tissue spectra were calculated using the tissue equivalent molecular formula C5H40O18N. The method involves folding the known bremsstrahlung spectrum shape with the cross section for each possible decay mode in each element which leads to neutron production. The partial photoneutron cross sections used have been derived from published data

  7. Screening Effects on Nonrelativistic Bremsstrahlung in the Scattering of Electrons by Neutral Atoms

    Science.gov (United States)

    Jung, Young-Dae; Lee, Kun-Sang

    1995-01-01

    Atomic screening effects on nonrelativistic electron-atom bremsstrahlung radiation are investigated using a simple analytic solution of the Thomas-Fermi model for many-electron atoms. The Born approximation is assumed for the initial and final states of the projectile electron. The results show that the screening effect is important in the soft radiation region and is decreasing with increasing radiation. These results help provide correct information about the behavior of bound electrons in the target atom in bremsstrahlung processes.

  8. Dose assessment of Bremsstrahlung induced by beta isotopes of Uranium-238 series in human tissues

    International Nuclear Information System (INIS)

    In the natural Uranium-238 decay series, pure beta isotopes such as 234Th, 234Pa, 214Pb, 214Bi, 210Pb and 210Bi are released. These beta isotopes having maximum beta energies and it induces the Bremsstrahlung radiation. The Bremsstrahlung component of these beta isotopes has been traditionally ignored in dosimetry calculations. This may be due to a lack of available methods for including this component in the calculations or to the belief that the contribution of this component is negligible compared to that of other emissions. The resulting hazard of Bremsstrahlung radiation may therefore be some of concern, at least theoretically, and should be systematically evaluated. In the present investigation, it has been estimated that the Bremsstrahlung dose of beta isotopes of Uranium-238 series such as 234Th, 234Pa, 214Pb, 214Bi, 210Pb and 210Bi in various body organs (Adrenals, Brain, Breasts, Gallbladder Wall, LLI Wall, Small Intestine, Stomach, ULI Wall, Heart Wall, Kidneys, Liver, Lungs, Muscle, Ovaries, Pancreas, Red Marrow, Bone Surfaces, Skin, Spleen, Testes, Thymus, Thyroid, Urine Bladder Wall, Uterus, Fetus, Placenta and Total Body). We have considered bone and muscle is target organs. These estimated values shows that the Bremsstrahlung radiation absorbed dose contribution from an organ to itself is very small compared to that from the beta source, but contribution to other organs is not always negligible. Hence the component of Bremsstrahlung dose to total dose should be considered in the environmental radioactivity dose calculations. (author)

  9. Studies of some isomeric yield ratios produced with bremsstrahlung

    CERN Document Server

    Kolev, D

    1998-01-01

    The experimental isomeric ratios for sup 5 sup 2 sup m sup , sup g Mn, sup 8 sup 6 sup m sup , sup g Y, sup 8 sup 7 sup m sup , sup g Y, sup 8 sup 9 sup m sup , sup g Zr, sup 1 sup 1 sup 0 sup m sup , sup g In, sup 1 sup 1 sup 1 sup m sup , sup g In, sup 1 sup 1 sup 2 sup m sup , sup g In, sup 1 sup 5 sup 2 sup m sup 1 sup , sup g Pm, sup 1 sup 5 sup 2 sup m sup 2 sup , sup m sup 1 Eu, sup 1 sup 6 sup 2 sup m sup , sup g Ho, sup 1 sup 6 sup 4 sup m sup , sup g Ho and sup 1 sup 7 sup 8 sup m sup , sup g Lu measured by the activation technique from different targets in (gamma, xnp) reactions (x<=3) at the bremsstrahlung end-point energy of 43 MeV are presented. The predictions of calculations performed by means of compound nucleus particle evaporation and final gamma-deexcitation were critically discussed. The importance of inclusion in the calculations of nonequilibrium particle emission and an adequate gamma-decay mode of isomeric nuclei was considered for some of the reactions investigated.

  10. Development of bremsstrahlung detection type tritium gas monitoring system, (1)

    International Nuclear Information System (INIS)

    A tritium monitoring system by means of bremsstrahlung detecting was developed. A prototype system consisted of a sampling cylinder, a gas circulating apparatus, an NaI(T1) detector, an amplifier and a multichannel analyzer. The sizes of sampling cylinders used 208 mm phi x 290; 170; 70 mmH, 133 mm phi x 292; 172; 72 mmH and 55 mm phi x 294; 174; 74 mmH, respectively. The sensitivity of prototype system was from 12 to 57 cps/μCi.cm-3, depending on the size of sampling cylinder and an efficiency of NaI(T1) detector. When pulses due to breamsstrahlungs with energy from 4 to 17 keV were counted, the minimum detectable concentration of the prototype tritium monitoring system was obtained to be 5.2 x 10-3 μCi/cm3. It was evaluated that the detectable range of concentration was from 1 x 10-2 to 1 x 103 μCi/cm3. (author)

  11. Bremsstrahlung in carbon thick targets by proton incidence

    International Nuclear Information System (INIS)

    The subtraction of the continuum from an X-ray spectrum emitted by proton bombardment is usually carried out by means of a mathematical fitting. The purpose of the present work is to develop an analytical function to model the continuous spectrum generated in a PIXE experiment for different incident beam energies in carbon thick targets. With this purpose, PIXE spectra of a carbon bulk sample were measured in an ion accelerator. The proton beam energies were varied between 0.7 MeV and 2 MeV and the X-rays generated were collected by an energy dispersive spectrometer. The spectra analysis was performed taking into account the main effects underlying the production of the continuous spectrum. Nevertheless, for the cases considered here, it was found that the atomic bremsstrahlung is the most important and other contributions were neglected. The experimental spectra from carbon thick targets were corrected by self-absorption and detector efficiency. The results show that the spectral shape corresponding to thick targets corrected by these effects is similar to the functional behavior presented by thin targets

  12. A Single Bremsstrahlung Monitor to Measure Luminosity at LEP

    CERN Multimedia

    2002-01-01

    The luminosity, the beam divergence and the longitudinal polarization can be measured at an interaction point of LEP by dectecting the energy, the angular distribution and the circular polarization of the single bremsstrahlung photons (SB) emitted at very forward angle. The luminosity can be measured by this met than by the conventional method of detecting small angle Bhabha scattering. The bunch to bunch relative luminosity can be monitored at a few per mil level in few minutes. Absolute values of the luminosity and of the polarization can be measured with a precision of the order of 1\\%. \\\\ \\\\ The apparatus to detect SB photons consists of a low Z absorber and of an EM calorimeter made of lead and scintillating fibres. Both the total energy and the space distribution of the SB photons are measured. This apparatus has been designed and built at the Department of Physics and INFN Section of the University of Rome ``La Sapienza''. Later on, together with suitable monocrystal converters, it may be used also for...

  13. Tomography of the fast electron Bremsstrahlung emission during lower hybrid current drive on Tore Supra

    Energy Technology Data Exchange (ETDEWEB)

    Peysson, Y.; Imbeaux, F. [Association Euratom-CEA, CEA/Cadarache, Dept. de Recherches sur la Fusion Controlee (DRFC), 13 - Saint-Paul-lez-Durance (France)

    1999-04-01

    A new tomography dedicated to detailed studies of the fast electron Bremsstrahlung emission in the hard X-ray (HXR) energy range between 20 and 200 keV during lower hybrid (LH) current drive experiments on the TORE SUPRA tokamak [Equipe TORE SUPRA, in Proceedings of the 15. Conference on Plasma Physics and Controlled Nuclear Fusion Research, Seville (International Atomic Energy Agency, Vienna, 1995), 1, AIEA-CN-60 / A1-5, p. 105] is presented. Radiation detection is performed by cadmium telluride(CdTe) semiconductors, which have most of the desirable features for a powerful diagnosing of magnetically confined hot plasmas - compact size, high X-ray stopping efficiency, fast timing characteristics, good energy resolution, no sensitivity to magnetic field, reasonable susceptibility to performance degradation from neutron/{gamma}-induced damages. This instrument is made of two independent cameras viewing a poloidal cross-section of the plasma, with respectively 21 and 38 detectors. A coarse spectrometry - 8 energy channels - is carried out for each chord, with an energy resolution of 20 keV. The spatial resolution in the core of the plasma is 4-5 cm, while the time sampling may be lowered down to of 2-4 ms. Powerful inversion techniques based on maximum entropy or regularization algorithms take fully advantage of the large number of line-integrated measurements for very robust estimates of the local HXR profiles as a function of time and photon energy. A detailed account of main characteristics and performances of the diagnostic is reported as well as preliminary results on LH current drive experiments. (authors)

  14. Impulsive solar X-ray bursts. III - Polarization, directivity, and spectrum of the reflected and total bremsstrahlung radiation from a beam of electrons directed toward the photosphere

    Science.gov (United States)

    Langer, S. H.; Petrosian, V.

    1977-01-01

    The paper presents the spectrum, directivity, and state of polarization of the bremsstrahlung radiation expected from a beam of high-energy electrons spiraling along radial magnetic field lines toward the photosphere. A Monte Carlo method is then described for evaluation of the spectrum, directivity, and polarization of X-rays diffusely reflected from stellar photospheres. The accuracy of the technique is evaluated through comparison with analytic results. The calculated characteristics of the incident X-rays are used to evaluate the spectrum, directivity, and polarization of the reflected and total X-ray fluxes. The results are compared with observations.

  15. PEBSI - A Monte Carlo simulator for bremsstrahlung arising from electrons colliding with thin solid-state targets

    CERN Document Server

    Weber, G; Surzhykov, A; Yasuda, M; Yerokhin, V A; Stöhlker, Th

    2012-01-01

    We present a Monte Carlo code dedicated to the simulation of bremsstrahlung arising in collisions of polarized electrons with thin target foils. The program consists of an electron transport algorithm taking into account elastic electron-nucleus scattering and inelastic collisions with target electrons as well as a treatment of polarized-electron bremsstrahlung emission. Good agreement is found between the predictions of the electron transport code and data stemming from other simulation programs and experiments. In addition, we present first results from the bremsstrahlung simulation which indicate a significant decrease in the degree of linear polarization of bremsstrahlung even for the thinnest gold targets considered.

  16. Gas bremsstrahlung studies for medium energy electron storage rings using FLUKA Monte Carlo code

    Science.gov (United States)

    Sahani, Prasanta Kumar; Haridas, G.; Sinha, Anil K.; Hannurkar, P. R.

    2016-02-01

    Gas bremsstrahlung is generated due to the interaction of the stored electron beam with residual gas molecules of the vacuum chamber in a storage ring. As the opening angle of the bremsstrahlung is very small, the scoring area used in Monte Carlo simulation plays a dominant role in evaluating the absorbed dose. In the present work gas bremsstrahlung angular distribution and absorbed dose for the energies ranging from 1 to 5 GeV electron storage rings are studied using the Monte Carlo code, FLUKA. From the study, an empirical formula for gas bremsstrahlung dose estimation was deduced. The results were compared with the data obtained from reported experimental values. The results obtained from simulations are found to be in very good agreement with the reported experimental data. The results obtained are applied in estimating the gas bremsstrahlung dose for 2.5 GeV synchrotron radiation source, Indus-2 at Raja Ramanna Centre for Advanced Technology, India. The paper discusses the details of the simulation and the results obtained.

  17. Can a many-nucleon structure be visible in bremsstrahlung emission during $\\alpha$ decay?

    CERN Document Server

    Maydanyuk, Sergei P; Zou, Li-Ping

    2015-01-01

    We analyze if the nucleon structure of the $\\alpha$ decaying nucleus can be visible in the experimental bremsstrahlung spectra of the emitted photons which accompany such a decay. We develop a new formalism of the bremsstrahlung model taking into account distribution of nucleons in the $\\alpha$ decaying nuclear system. We conclude the following: (1) After inclusion of the nucleon structure into the model the calculated bremsstrahlung spectrum is changed very slowly for a majority of the $\\alpha$ decaying nuclei. However, we have observed that visible changes really exist for the $^{106}{\\rm Te}$ nucleus ($Q_{\\alpha}=4.29$ MeV, $T_{1/2}$=70 mks) even for the energy of the emitted photons up to 1 MeV. This nucleus is a good candidate for future experimental study of this task. (2) Inclusion of the nucleon structure into the model increases the bremsstrahlung probability of the emitted photons. (3) We find the following tendencies for obtaining the nuclei, which have bremsstrahlung spectra more sensitive to the ...

  18. Z-dependence of thick-target bremsstrahlung produced by monoenergetic low-energy electrons

    Science.gov (United States)

    Czarnecki, S.; Short, A.; Williams, S.

    2016-07-01

    The dependence of thick-target bremsstrahlung emitted by low-energy beams of monoenergetic electrons on the atomic number of the target material has been investigated experimentally for incident electron energies of 4.25 keV and 5.00 keV using thick aluminum, copper, silver, tungsten, and gold targets. Experimental data suggest that the intensity of the thick-target bremsstrahlung emitted is more strongly dependent on the atomic number of the target material for photons with energies that are approximately equal to the energy of the incident electrons than at lower energies, and also that the dependence of thick-target bremsstrahlung on the atomic number of the target material is stronger for incident electrons of higher energies than for incident electrons of lower energies. The results of the experiments are compared to the results of simulations performed using the PENELOPE program (which is commonly used in medical physics) and to thin-target bremsstrahlung theory, as well. Comparisons suggest that the experimental dependence of thick-target bremsstrahlung on the atomic number of the target material may be slightly stronger than the results of the PENELOPE code suggest.

  19. Anomalous inverse bremsstrahlung heating of laser-driven plasmas

    Science.gov (United States)

    Kundu, Mrityunjay

    2016-05-01

    Absorption of laser light in plasma via electron-ion collision (inverse bremsstrahlung) is known to decrease with the laser intensity as I 0 -3/2 or with the electron temperature as T e -3/2 where Coulomb logarithm ln Λ = 0.5ln(1 + k 2 min/k 2 max) in the expression of electron-ion collision frequency v ei is assumed to be independent of ponderomotive velocity v 0 = E0/ω which is unjustified. Here k -1 min = v th/max(ω, ω p), and k -1 max = Z/v 2 th are maximum and minimum cut-off distances of the colliding electron from the ion, v th = √T e is its thermal velocity, ω, ω p are laser and plasma frequency. Earlier with a total velocity v = (v 2 0 + v 2 th)1/2 dependent ln Λ(v) it was reported that v ei and corresponding fractional laser absorption (α) initially increases with increasing intensity, reaches a maximum value, and then fall according to the conventional I 0 -3/2 scaling. This anomalous increase in v ei and α may be objected due to an artifact introduced in ln Λ(v) through k-1 min ∝ v. Here we show similar anomalous increase of v ei and α versus I 0 (in the low temperature and under-dense density regime) with quantum and classical kinetic models of v ei without using ln Λ, but a proper choice of the total velocity dependent inverse cut-off length kmax -1 ∝ v 2 (in classical case) or kmax ∝ v (in quantum case). For a given I 0 15 eV, anomalous growth of vei and a disappear. The total velocity dependent k max in kinetic models, as proposed here, may explain anomalous increase of a with I 0 measured in some earlier laser-plasma experiments. This work may be important to understand collisional absorption in the under-dense pre-plasma region due to low intensity pre-pulses and amplified spontaneous emission (ASE) pedestal in the context of laser induced inertial confinement fusion.

  20. Thermalisation and hard X-ray bremsstrahlung efficiency of self-interacting solar flare fast electrons

    CERN Document Server

    Galloway, R K; MacKinnon, A L; Brown, J C

    2010-01-01

    Most theoretical descriptions of the production of solar flare bremsstrahlung radiation assume the collision of dilute accelerated particles with a cold, dense target plasma, neglecting interactions of the fast particles with each other. This is inadequate for situations where collisions with this background plasma are not completely dominant, as may be the case in, for example, low-density coronal sources. We aim to formulate a model of a self-interacting, entirely fast electron population in the absence of a dense background plasma, to investigate its implications for observed bremsstrahlung spectra and the flare energy budget. We derive approximate expressions for the time-dependent distribution function of the fast electrons using a Fokker-Planck approach. We use these expressions to generate synthetic bremsstrahlung X-ray spectra as would be seen from a corresponding coronal source. We find that our model qualitatively reproduces the observed behaviour of some flares. As the flare progresses, the model's...

  1. Bremsstrahlung emission probability in the {alpha} decay of {sup 210}Po

    Energy Technology Data Exchange (ETDEWEB)

    Boie, Hans-Hermann

    2009-06-03

    A high-statistics measurement of bremsstrahlung emitted in the {alpha} decay of {sup 210}Po has been performed. The measured differential emission probabilities, which could be followed up to {gamma}-energies of {proportional_to} 500 keV, allow for the first time for a serious test of various model calculations of the bremsstrahlung accompanied {alpha} decay. It is shown that corrections to the {alpha}-{gamma} angular correlation due to the interference between the electric dipole and quadrupole amplitudes and due to the relativistic character of the process have to be taken into account. With the experimentally derived angular correlation the measured energydifferential bremsstrahlung emission probabilities show excellent agreement with the fully quantum mechanical calculation. (orig.)

  2. Impact of Nucleon-Nucleon Bremsstrahlung Rates Beyond One-Pion Exchange

    CERN Document Server

    Bartl, Alexander; Janka, Hans-Thomas; Schwenk, Achim

    2016-01-01

    Neutrino-pair production and annihilation through nucleon-nucleon bremsstrahlung is included in current supernova simulations by rates that are based on the one-pion-exchange approximation. Here we explore the consequences of bremsstrahlung rates based on a modern nuclear interactions for proto-neutron star cooling and the corresponding neutrino emission. We find that despite a reduction of the bremsstrahlung emission by a factor of 2-5 in the neutrinospheric region, models with the improved treatment exhibit only $\\lesssim$5% changes of the neutrino luminosities and an increase of $\\lesssim$0.7 MeV of the average energies of the radiated neutrino spectra, with the largest effects for the antineutrinos of all flavors and at late times. Overall, the proto-neutron star cooling evolution is slowed down modestly by $\\lesssim$0.5-1 s.

  3. Electron spectroscopy at the high-energy endpoint of electron-nucleus bremsstrahlung

    Energy Technology Data Exchange (ETDEWEB)

    Hillenbrand, Pierre-Michel [GSI Darmstadt (Germany); Univ. Giessen (Germany); Hagmann, Siegbert [GSI Darmstadt (Germany); Univ. Frankfurt (Germany); Banas, Dariusz [Univ. Kielce (Poland); Brandau, Carsten [Extreme Matter Institute Darmstadt (Germany); Univ. Giessen (Germany); Doerner, Reinhard [Univ. Frankfurt (Germany); De Filippo, Enrico [INFN Catania (Italy); Gumberidze, Alexandre [Extreme Matter Institute Darmstadt (Germany); Guo, Dalong [IMP Lanzhou (China); Univ. Beijing (China); Jakubassa-Amundsen, Doris [Univ. Muenchen (Germany); Lestinsky, Michael; Spillmann, Uwe [GSI Darmstadt (Germany); Litvinov, Yuri [GSI Darmstadt (Germany); Univ. Heidelberg (Germany); Mueller, Alfred; Schippers, Stefan [Univ. Giessen (Germany); Rothard, Hermann [CIRIL GANIL Caen (France); Surzhykov, Andrey [Helmholtz-Institut Jena (Germany); Trotsenko, Sergey [GSI Darmstadt (Germany); Helmholtz-Institut Jena (Germany); Voitkiv, Alexander [MPI-K Heidelberg (Germany); Yerokhin, Vladimir [Petersburg State Univ. (Russian Federation); Stoehlker, Thomas [GSI Darmstadt (Germany); Helmholtz-Institut Jena (Germany); Univ. Jena (Germany)

    2014-07-01

    The high-energy endpoint of electron-nucleus bremsstrahlung has been studied in inverse kinematics: For collisions U{sup 88+}+N{sub 2} → U{sup 88+}+[N{sub 2}{sup +}]{sup *} + e{sup -} + γ the energy distribution of electrons scattered under θ{sub e}{sup lab} = 0 {sup circle} with v{sub e} ∼ v{sub proj} was measured coincident with the bremsstrahlung photons emitted under various angles θ{sub γ}{sup lab}. The triple-differential cross sections provide a stringent test for the fully relativistic theory of electron-nucleus bremsstrahlung. Furthermore the studied process, also termed radiative electron capture to continuum RECC, was compared to the competing processes of non-radiative electron capture to continuum ECC and the electron loss to continuum ELC.

  4. ELBA, Bremsstrahlung Dose from Isotropic Electron Flux on Plane Al Shield

    International Nuclear Information System (INIS)

    1 - Description of problem or function: ELBA takes an incident isotropic electron flux with a given differential energy spectrum and calculates the dose rate received from Bremsstrahlung produced in a plane aluminium shield placed in front of the receiver. There is an option to also calculate the electron dose rate from the same source. 2 - Method of solution: The electron differential spectrum as a function of depth is inferred by assuming that electrons travel straight ahead and that distance travelled and energy are related by a range-energy relationship. The electron dose rate at a given depth is calculated by integrating, over energy and direction, the product of the electron flux, the stopping power, and the appropriate flux- to-dose rate conversion factor. The Bremsstrahlung source is assumed to be plane and isotropic at a given depth. This source is defined as the integral over energy and direction of the product of photon energy, the differential Bremsstrahlung spectrum from electrons of a given energy, and the electron flux differential spectrum. The differential Bremsstrahlung spectrum is derived from the Born approximation cross section multiplied by a correction factor. The Bremsstrahlung dose rate is obtained by integrating, over photon energy and slab volume, the product of the Bremsstrahlung source, photon energy flux-to-dose rate conversion factor, buildup factor, and attenuation kernel. The buildup factor assumed is a plane isotropic buildup factor generate by Monte Carlo calculations. The integrations are performed by evaluating the integrand at the midpoint of each integration step, multiplying by the step width, and summing the result. The incident electron spectrum, dose rate conversion factors, and range formula coefficients are input by the user. The buildup factor information is contained in three Data statements in subroutine BURP. 3 - Restrictions on the complexity of the problem: There are limitations on the dimensions of certain arrays

  5. Evaluation of bremsstrahlung contribution to photon transport in coupled photon-electron problems

    Science.gov (United States)

    Fernández, Jorge E.; Scot, Viviana; Di Giulio, Eugenio; Salvat, Francesc

    2015-11-01

    The most accurate description of the radiation field in x-ray spectrometry requires the modeling of coupled photon-electron transport. Compton scattering and the photoelectric effect actually produce electrons as secondary particles which contribute to the photon field through conversion mechanisms like bremsstrahlung (which produces a continuous photon energy spectrum) and inner-shell impact ionization (ISII) (which gives characteristic lines). The solution of the coupled problem is time consuming because the electrons interact continuously and therefore, the number of electron collisions to be considered is always very high. This complex problem is frequently simplified by neglecting the contributions of the secondary electrons. Recent works (Fernández et al., 2013; Fernández et al., 2014) have shown the possibility to include a separately computed coupled photon-electron contribution like ISII in a photon calculation for improving such a crude approximation while preserving the speed of the pure photon transport model. By means of a similar approach and the Monte Carlo code PENELOPE (coupled photon-electron Monte Carlo), the bremsstrahlung contribution is characterized in this work. The angular distribution of the photons due to bremsstrahlung can be safely considered as isotropic, with the point of emission located at the same place of the photon collision. A new photon kernel describing the bremsstrahlung contribution is introduced: it can be included in photon transport codes (deterministic or Monte Carlo) with a minimal effort. A data library to describe the energy dependence of the bremsstrahlung emission has been generated for all elements Z=1-92 in the energy range 1-150 keV. The bremsstrahlung energy distribution for an arbitrary energy is obtained by interpolating in the database. A comparison between a PENELOPE direct simulation and the interpolated distribution using the data base shows an almost perfect agreement. The use of the data base increases

  6. Complete gluon bremsstrahlung corrections to the process b -> s l+ l-

    OpenAIRE

    Asatryan, H. H.; Asatrian, H. M.; Greub, C.; M. Walker

    2002-01-01

    In a recent paper, we presented the calculation of the order (alpha_s) virtual corrections to b->s l+ l- and of those bremsstrahlung terms which are needed to cancel the infrared divergences. In the present paper we work out the remaining order(alpha_s) bremsstrahlung corrections to b->s l+ l- which do not suffer from infrared and collinear singularities. These new contributions turn out to be small numerically. In addition, we also investigate the impact of the definition of the charm quark ...

  7. Complete gluon bremsstrahlung corrections to the process b -> s l+ l-

    CERN Document Server

    Asatryan, H H; Greub, Christoph; Walker, M

    2002-01-01

    In a recent paper, we presented the calculation of the order (alpha_s) virtual corrections to b->s l+ l- and of those bremsstrahlung terms which are needed to cancel the infrared divergences. In the present paper we work out the remaining order(alpha_s) bremsstrahlung corrections to b->s l+ l- which do not suffer from infrared and collinear singularities. These new contributions turn out to be small numerically. In addition, we also investigate the impact of the definition of the charm quark mass on the numerical results.

  8. Bremsstrahlung from Electrons and Positrons in Peripheral Relativistic Heavy Ion Collisions

    OpenAIRE

    Hencken, Kai; Trautmann, Dirk; Baur, Gerhard

    1999-01-01

    We study the spectrum of the bremsstrahlung photons coming from the electrons and positrons, which are produced in the strong electromagnetic fields present in peripheral relativistic heavy ion collisions. We compare different approaches, making use of the exact pair production cross section in heavy ion collisions as well as the double equivalent photon approximation.

  9. Virtual-bremsstrahlung production in proton-proton scattering and proton-deuteron capture

    NARCIS (Netherlands)

    Messchendorp, Johannes Gerhardus

    1999-01-01

    The well-known coupling of the photon with the nucleon together with the fact that photons (or any electromagnetic (e.m.) probe) interact only relatively weakly with nucleons, make bremsstrahlung production an ideal tool to study details of the nucleon-nucleon interaction. In this thesis dilepton pr

  10. EFFECTS OF MESON-DECAY DIAGRAMS IN PROTON-PROTON BREMSSTRAHLUNG

    NARCIS (Netherlands)

    DEJONG, F; NAKAYAMA, K

    1995-01-01

    We investigate the effect of meson-decay diagrams on the proton-proton bremsstrahlung process. We explicitly include short-range correlations by calculating single- and double-scattering diagrams using an NN T-matrix interaction. We find that in general these diagrams interfere destructively with th

  11. Absolute intensity of internal bremsstrahlung from the electron capture decay of 125I

    International Nuclear Information System (INIS)

    The absolute intensity of the internal bremsstrahlung spectrum accompanying the electron capture decay of 125I has been measured and compared to the recent calculation of Suric et al. The measured intensity above the 1s end point is found to be (86±10)% of the calculated intensity

  12. THE BREMSSTRAHLUNG ISOCHROMAT SPECTRA OF D(0) TRANSITION-METAL OXIDES

    NARCIS (Netherlands)

    SORIANO, L; ABBATE, M; ALDERS, D; SANZ, JM

    1994-01-01

    We present and discuss the bremsstrahlung isochromat spectra (BIS) of four d0 transition-metal oxides, namely ZrO2, HfO2, Nb2O5, and Ta2O5. The spectra are related to the density of unoccupied states in the conduction band. They give directly the magnitude of the crystal-field splitting and the disp

  13. Bremsstrahlung from relativistic bare heavy ions: Nuclear and electronic contributions in amorphous and crystalline materials

    DEFF Research Database (Denmark)

    Jensen, Tue Vissing; Sørensen, Allan Hvidkjær

    2013-01-01

    A charged particle emits bremsstrahlung while traversing matter. We calculate the radiation cross section for bare heavy ions penetrating amorphous materials and single crystals at highly relativistic energies. The main component originates in scattering of the virtual photons of screened target...... in a pronounced directional dependence of the energy loss of bare heavy ions at extreme relativistic energies....

  14. Experimental bremsstrahlung yields for MeV proton bombardment of beryllium and carbon

    Energy Technology Data Exchange (ETDEWEB)

    Cohen, David D. [Institute for Environmental Research, Australian Nuclear Science and Technology Organisation, Private Mail Bag 1, Menai, NSW 2234 (Australia)], E-mail: dcz@ansto.gov.au; Stelcer, Eduard; Siegele, Rainer; Ionescu, Mihail; Prior, Michael [Institute for Environmental Research, Australian Nuclear Science and Technology Organisation, Private Mail Bag 1, Menai, NSW 2234 (Australia)

    2008-04-15

    Experimental bremsstrahlung yields for 2, 3 and 4 MeV protons on thin beryllium and carbon targets have been measured. The yields have been corrected for detector efficiency, self-absorption in the target and fitted to 9th order polynomials over the X-ray energy range 1-10 keV for easy comparison with theoretical calculations.

  15. Neutrino-pair emission in a strong magnetic field

    NARCIS (Netherlands)

    van Dalen, ENE; Dieperink, AEL; Sedrakian, A; Timmermans, RGE

    2000-01-01

    We study the neutrino emissivity of strongly magnetized neutron stars due to the charged and neutral current couplings of neutrinos to baryons in strong magnetic fields. The leading order neutral current process is the one-body neutrino-pair bremsstrahlung, which does not have an analogue in the zer

  16. Numerical test of polarization sum rules for the triply differential bremsstrahlung cross section in electron-nucleus encounters

    CERN Document Server

    Jakubassa-Amundsen, D H

    2016-01-01

    Inspired by the work of Pratt and coworkers on a sum rule for the polarization correlations in electron bremsstrahlung when the outgoing electron is not observed, we derive the corresponding sum rule for the elementary process of bremsstrahlung. This sum rule is valid for arbitrary electron wavefunctions provided the electron is emitted in the reaction plane. The numerical evaluation of this sum rule within the Dirac partial-wave theory for bare inert spin-zero nuclei and collision energies in the range of 1-10 MeV reveals violations for high nuclear charge. Such violations serve as a measure of the inaccuracies in the bremsstrahlung calculations.

  17. Measurement of gas Bremsstrahlung at the Pohang Light Source by using a CeF3 scintillator

    International Nuclear Information System (INIS)

    We have measured the gas Bremsstrahlung photon energy from the 2.5-GeV electron storage ring at the Pohang Light Source (PLS). Gas Bremsstrahlung was generated in the straight section of the beam-diagnosis beamline 1C1 with an effective length of 5.3 m. We present the measurement results for the Bremsstrahlung photon energy spectrum and the photon flux, which were obtained by using a CeF3 calorimeter. The calorimeter consisted of nine CeF3 blocks, each being 3.3 x 3.3 x 33 cm3, stacked into a 3 x 3 array. The Bremsstrahlung photon flux above 40 MeV was measured to be 218 s-1 at an electron beam current of 180 mA.

  18. Collimator and energy window optimization for ⁹⁰Y bremsstrahlung SPECT imaging: A SIMIND Monte Carlo study.

    Science.gov (United States)

    Roshan, Hoda Rezaei; Mahmoudian, Babak; Gharepapagh, Esmaeil; Azarm, Ahmadreza; Islamian, Jalil Pirayesh

    2016-02-01

    Treatment efficacy of radioembolization using Yttrium-90 ((90)Y) microspheres is assessed by the (90)Y bremsstrahlung single photon emission computed tomography (SPECT) imaging following radioembolization. The radioisotopic image has the potential of providing reliable activity map of (90)Y microspheres distribution. One of the main reasons of the poor image quality in (90)Y bremsstrahlung SPECT imaging is the continuous and broad energy spectrum of the related bremsstrahlung photons. Furthermore, collimator geometry plays an impressive role in the spatial resolution, sensitivity and image contrast. Due to the relatively poor quality of the (90)Y bremsstrahlung SPECT images, we intend to optimize the medium-energy (ME) parallel-hole collimator and energy window. The Siemens e.cam gamma camera equipped with a ME collimator and a voxelized phantom was simulated by the SImulating Medical Imaging Nuclear Detectors (SIMIND) program. We used the SIMIND Monte Carlo program to generate the (90)Y bremsstrahlung SPECT projection of the digital Jaszczak phantom. The phantom consist of the six hot spheres ranging from 9.5 to 31.8mm in diameter, which are used to evaluate the image contrast. In order to assess the effect of the energy window on the image contrast, three energy windows ranging from 60 to 160 KeV, 160 to 400 KeV, and 60 to 400 KeV were set on a (90)Y bremsstrahlung spectrum. As well, the effect of the hole diameter of a ME collimator on the image contrast and bremsstrahlung spectrum were investigated. For the fixed collimator and septa thickness values (3.28 cm and 1.14 mm, respectively), a hole diameter range (2.35-3.3mm) was chosen based on the appropriate balance between the spatial resolution and sensitivity. The optimal energy window for (90)Y bremsstrahlung SPECT imaging was extended energy window from 60 to 400 KeV. Besides, The optimal value of the hole diameter of ME collimator was obtained 3.3mm. Geometry of the ME parallel-hole collimator and energy

  19. Bayesian analysis of the effective charge from spectroscopic bremsstrahlung measurement in fusion plasmas

    Science.gov (United States)

    Krychowiak, M.; König, R.; Klinger, T.; Fischer, R.

    2004-11-01

    At the stellarator Wendelstein 7-AS (W7-AS) a spectrally resolving two channel system for the measurement of line-of-sight averaged Zeff values has been tested in preparation for its planned installation as a multichannel Zeff-profile measurement system on the stellarator Wendelstein 7-X (W7-X) which is presently under construction. The measurement is performed using the bremsstrahlung intensity in the wavelength region of ultraviolet to near infrared. The spectrally resolved measurement allows to eliminate signal contamination by line radiation. For statistical data analysis a procedure based on Bayesian probability theory has been developed. With this method it is possible to estimate the bremsstrahlung background in the measured signal and its error without the necessity to fit the spectral lines. For evaluation of the random error in Zeff the signal noise has been investigated. Furthermore, the linearity and behavior of the charge-coupled device detector at saturation has been analyzed.

  20. Experimental and analytical study of the bremsstrahlung radiation production at low energies

    International Nuclear Information System (INIS)

    The bremsstrahlung photon beam from an X-ray tube with chromium anode has been studied, for an electron energy of 60 Kev. In the experimental step, a new measurement method has been developed. This is based on the detection and measurement of the fluorescence produced when the photons from the tube impinge on targets which are used as calibrated flux monitors. The composition and physical characteristics of the targets are well-known. In the steps of experimental data treatment, an analytical study of the theoretical models describing thick target bremsstrahlung yield is performed. A factorization which accounts for the elemental physical processes is obtained, employing simple mathematical functions. The characteristic parameters found in the numerical fit process lead to results in good agreement with the experimental observations from other authors and predict theoretical exposure values in perfect agreement with the exposures measured for X-ray beams generated in several operating conditions. (author)

  1. Electron accelerator-based production of molybdenum-99: Bremsstrahlung and photoneutron generation from molybdenum vs. tungsten

    Science.gov (United States)

    Tsechanski, A.; Bielajew, A. F.; Archambault, J. P.; Mainegra-Hing, E.

    2016-01-01

    A new "one-stage" approach for production of 99Mo and other radioisotopes by means of an electron linear accelerator is described. It is based on using a molybdenum target both as a bremsstrahlung converter and as a radioisotope producing target for the production of 99Mo via the photoneutron reaction 100Mo(γ,n)99Mo. Bremsstrahlung characteristics, such as bremsstrahlung efficiency, angular distribution, and energy deposition for molybdenum targets were obtained by means of the EGSnrc Monte Carlo simulation code system. As a result of our simulations, it is concluded that a 60 MeV electron beam incident on a thick Mo target will have greater bremsstrahlung efficiency than the same thickness (in units of r0) W target, for target thickness z > 1.84r0, where r0 is the electron range. A 50 MeV electron beam incident on a Mo target will result in greater bremsstrahlung efficiency than the same thickness W target (in units of r0) for target thickness case: z ⩾ 2.0r0. It is shown for the one-stage approach with thicknesses of (1.84-2.0)r0, that the 99Mo-production bremsstrahlung efficiency of a molybdenum target is greater by ∼100% at 30 MeV and by ∼70% at 60 MeV compared to the values for tungsten of the same thickness (in units of the appropriate r0) in the traditional two-stage approach (W converter and separate 99Mo producing target). This advantage of the one-stage approach arises from the fact that the bremsstrahlung produced is attenuated only once from attenuation in the molybdenum converter/target. In the traditional, two-stage approach, the bremsstrahlung generated in the W-converter/target is attenuated both in the converter in the 99Mo-producing molybdenum target. The photoneutron production yield of molybdenum and tantalum (as a substitute for tungsten) target was calculated by means of the MCNP5 transport code. On the basis of these data, the specific activity for the one-stage approach of three enriched 100Mo-targets of a 2 cm diameter and

  2. Effect of Degenerated Particles on Internal Bremsstrahlung of Majorana Dark Matter

    CERN Document Server

    Okada, Hiroshi

    2014-01-01

    Gamma-ray generated by annihilation or decay of dark matter can be its smoking gun signature. In particular, gamma-ray coming from internal bremsstrahlung of dark matter is promising since it can be a leading emission of sharp gamma-ray. However if thermal production of Majorana dark matter is considered, the derived cross section for internal bremsstrahlung becomes too small to be observed by future gamma-ray experiments. We consider a framework to achieve an enhancement of the cross section by taking into account degenerated particles with dark matter. We find that the enhancement of about order one is possible without conflict with the dark matter relic density. Due to the enhancement, it would be tested by the future experiments such as GAMMA-400 and CTA.

  3. Determination of effective bremsstrahlung spectra and electron contamination for photon dose calculations

    International Nuclear Information System (INIS)

    A method is described for determining an effective, depth dose consistent bremsstrahlung spectra for high-energy photon beams using depth dose curves measured in water. A simple, analytical model with three parameters, together with the nominal accelerating potential is used to characterise the bremsstrahlung spectra. The model is used to compute weights for depth dose curves from monoenergetic photons. These monoenergetic depth doses, calculated with the convolution method from Monte Carlo generated point spread functions (PSF), are added to yield the pure photon depth dose distribution. The parameters of the analytical spectrum model are determined using an iterative technique to minimise the difference between calculated and measured depth dose curves. The influence from contaminant electrons is determined from the difference between the calculated and the measured depth dose. (author)

  4. Indigenous facility development for studying an elementary radiation process: atomic-field Bremsstrahlung

    International Nuclear Information System (INIS)

    An indigenous setup for studying the process of atomic-field Bremsstrahlung produced from the interaction of keV electrons with a solid or a gaseous target has been developed and described. The setup consists of a high-vacuum scattering chamber, a home-built keV electron gun with a replaceable tungsten filament cathode, an isolated floating high-voltage control unit, signal processing electronic modules and a data-acquisition system comprising of an IBM PC/XT 4-K multichannel analyser. The performance of the setup has been tested and used for accumulating data for Bremsstrahlung spectra from 7.0 keV electrons incident on thin Ag and Au targets. These spectra have been analyzed and discussed in light of the semiclassical and the quantum calculations. The agreement between experiment and theory is found to be satisfactory within the experimental uncertainty of the measurements. (author). 10 refs., 5 figs., 1 tab

  5. Investigation of the partner-potentials from supersymmetric quantum mechanics by bremsstrahlung

    International Nuclear Information System (INIS)

    With the explicit example of α + α scattering we emphasize the incompleteness of using just the on-shell properties in any inversion procedure. A deep, energy-independent and angular-momentum-independent effective local potential is constructed to reproduce the phase shifts from a single-configuration microscopic resonating-group method (RGM) calculation for α + α scattering up to E = 16 MeV. From this we derive its phase-shift-equivalent shallow supersymmetric partner-potentials by eliminating the bound states which are unphysical due to the Pauli principle. These deep and shallow potentials are used to calculate bremsstrahlung emission in α + α collision and compared with the results from RGM as a means to investigate their wave functions. While the bremsstrahlung cross sections from RGM and the deep potential resemble each other, those of the shallow potentials are distinctly different. (orig.)

  6. An instrument for the investigation of actinides with spin resolved photoelectron spectroscopy and bremsstrahlung isochromat spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Yu, S.-W. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Tobin, J. G. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Chung, B. W. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2011-01-01

    A new system for spin resolved photoelectron spectroscopy and bremsstrahlung isochromat spectroscopy has been built and commissioned at Lawrence Livermore National Laboratory for the investigation of the electronic structure of the actinides.Actinide materials are very toxic and radioactive and therefore cannot be brought to most general user facilities for spectroscopic studies. The technical details of the new system and preliminary data obtained therein will be presented and discussed.

  7. Self-absorption correction factor for a sample excited by the bremsstrahlung radiation

    CERN Document Server

    Mandal, A C; Mitra, D; Sarkar, M; Bhattacharya, D P

    2002-01-01

    A method of calculating the self-absorption correction factor for fluorescent X-rays from a sample excited by the bremsstrahlung has been described. As a typical example, the correction factors for K subalpha of Si and Cu for different tube voltages have been calculated. Polynomial fit of the correction factor against the tube voltage in the range 10-100 kV has been given for both the elements.

  8. The internal bremsstrahlung accompanying the β-dacay from 185W

    International Nuclear Information System (INIS)

    The internal bremsstrahlung (IB) spectrum accompanying the β-decay from 185W radionuclide has been measured. The obtained spectrum was analyzed into its constituting gamma lines taking into account all the proper corrections. The analyzed spectrum was compared with those theoretically calculated. The experimental results for the IB probability were found to be in good agreement with theoretical calculations especially with the shape corrected modified KUB theory of Nilsson up to 357.7 keV. (author)

  9. Monte Carlo simulation and analytical calculation of coherent Bremsstrahlung and its polarisation

    Energy Technology Data Exchange (ETDEWEB)

    Natter, F.A.; Grabmayr, P. E-mail: grabmayr@uni-tuebingen.de; Hehl, T.; Owens, R.O.; Wunderlich, S

    2003-12-01

    Spectral distributions for coherent and incoherent Bremsstrahlung produced by electrons on thin diamond radiators are calculated accurately by a Monte Carlo procedure. Realistic descriptions of the electron beam and the physical processes within the radiator have been implemented. Results are compared to measured data. A faster calculation at only a slight loss of precision is possible using analytical expressions which can be derived after simplifying assumptions.

  10. Investigation of Coulombic bremsstrahlung spectra of metallic targets for the photon energy region of 1-100keV.

    Science.gov (United States)

    Singh, Amrit; Dhaliwal, A S

    2016-09-01

    In the present paper, the formation of bremsstrahlung spectra by ordinary bremsstrahlung (OB) and polarization bremsstrahlung (PB) in metallic targets by (35)S beta particles has been investigated in the photon energy region of 1-100keV. From the experimental measurements and the theoretical results obtained from Elwert corrected (non-relativistic) Bethe Heitler (EBH) theory, modified Elwert factor (relativistic) (FmodBH) theories for OB and Avdonina and Pratt (FmodBH+PB) theory for total bremsstrahlung (BS) having the contribution of PB into OB, it has been found that the contribution of PB into BS in a target is limited to a low energy region only and also varies with the atomic number of target material. The FmodBH+PB theory is in agreement with the experimental results in low energy regions of the target, whereas at high energy region FmodBH is found to give better agreement. Further, the present experimental results indicate that the screening effects in the Coulombic bremsstrahlung process cannot be neglected in the high energy region, and the multiple scattering and secondary electron emissions effects in thick target are required to be taken into account in describing the bremsstrahlung process. PMID:27400163

  11. Studies on Neutron, Photon (Bremsstrahlung and Proton Induced Fission of Actinides and Pre-Actinides

    Directory of Open Access Journals (Sweden)

    H. Naik

    2015-08-01

    Full Text Available We present the yields of various fission products determined in the reactor neutron, 3.7-18.1 MeV quasi-mono energetic neutron, 8-80 MeV bremsstrahlung and 20-45 MeV proton induced fission of 232Th and 238U using radiochemical and off-line beta or gamma ray counting. The yields of the fission products in the bremsstrahlung induced fission natPb and 209Bi with 50- 70 MeV and 2.5 GeV based on off-line gamma ray spectrometric technique were also presented. From the yields of fission products, the mass chains yields were obtained using charge distribution correction. From the mass yield distribution, the peak-to-valley (P/V ratio was obtained. The role of excitation energy on the peak-to-valley ratio and fine structure such as effect of shell closure proximity and even-odd effect of mass yield distribution were examined. The higher yields of the fission products around A=133-134, 138-140 and 143-144 and their complementary products explained from the nuclear structure effect and role of standard I and II mode of asymmetric fission. In the neutron, photon (bremsstrahlung and proton induced fission, the asymmetric mass distribution for actinides (Th, U and symmetric distribution for pre-actinides (Pb, Bi were explained from different type of potential fission barrier

  12. Thermal Bremsstrahlung probing nuclear multifragmentation in nucleus-nucleus collisions around the Fermi energy

    International Nuclear Information System (INIS)

    The thermodynamical properties of nuclear matter at moderate temperatures and densities, in the vicinity of the predicted nuclear liquid-gas phase transition, are studied using as experimental probe the hard-photons (Eγ > 30 MeV) emitted in nucleus-nucleus collisions. Photon and charged-particle production in four different heavy-ion reactions (Ar36 + Au197, Ag107, Ni58, C12 at 60 A*MeV) is measured exclusively and inclusively coupling the TAPS photon spectrometer with two charged-particle and intermediate-mass-fragment detectors covering nearly 4π. We confirm that Bremsstrahlung emission in first-chance (off-equilibrium) proton-neutron collisions (pnγ) is the dominant origin of hard photons. We also firmly establish the existence of a thermal radiation component emitted in second-chance proton-neutron collisions. This thermal Bremsstrahlung emission takes place in semi-central and central nucleus-nucleus reactions involving heavy targets. We exploit this observation i) to demonstrate that thermal equilibrium is reached during the reaction, ii) to establish a new thermometer of nuclear matter based on Bremsstrahlung photons, iii) to derive the thermodynamical properties of the excited nuclear sources and, in particular, to establish a 'caloric curve' (temperature versus excitation energy), and iv) to assess the time-scales of the nuclear break-up process. (author)

  13. Dose calculation and measurement for bremsstrahlung at BL18U beamline of SSRF

    International Nuclear Information System (INIS)

    Background: Gas bremsstrahlung is one of the most important radiation sources that needs to be taken into consideration for shielding design of beamlines at the third generation synchrotron radiation light source. Shanghai Synchrotron Radiation Facility (SSRF) is one of the third generation synchrotron radiation light source in the world. The Protein Micro-crystallography Beamline (BL18U) is one of the commissioning beamlines and is a representative insertion device beamline at SSRF. Purpose: Estimation of radiation dose induced by scattering bremsstrahlung and photoneutrons at BL18U. Methods: Dose rate distribution induced by scattering bremsstrahlung and photoneutrons at BL18U are performed by Monte Carlo simulation code FLUKA. The radiation dose was analyzed with the variation of slits size, beam current at storage ring and the vacuum. Dose rate of photons and photoneutrons at the outside of the optical enclosure of BL18U were measured by using high sensitivity photon and neutron monitors. Results: The measurement results show that the reliability of the simulation. Conclusion: The simulation and measurement methods presented in this study can be applied to evaluate the dose rate level of other beamline stations at SSRF, and provide references to the shielding design for the following beamlines at SSRF in the near future. (authors)

  14. Bremsstrahlung-induced highly penetrating probes for nondestructive assay and defect analysis

    Science.gov (United States)

    Selim, F. A.; Wells, D. P.; Harmon, J. F.; Kwofie, J.; Spaulding, R.; Erickson, G.; Roney, T.

    2002-12-01

    Nondestructive assay and defect analysis probes based on bremsstrahlung-induced processes have been developed to identify elements and probe defects in large volume samples. Bremsstrahlung beams from (electron accelerators) with end-point energies both above and below neutron emission threshold have been used. Below neutron emission threshold these beams (from 6 MeV small pulsed linacs), which exhibit high penetration, create positrons via pair production inside the material and produce X-ray fluorescence (XRF) radiation. Chemical assays of heavy elements in thick samples up to 10 g/cm 2 thick are provided by energy dispersive XRF measurements. The pair-produced positrons annihilate within the material, thereby emitting 511 keV gamma radiation. Doppler broadening spectroscopy of the 511 keV radiation can be performed to characterize the material and measure defects in samples of any desired thickness. This technique has successfully measured induced strain due to tensile stress in steel samples of 0.64 cm thick. Bremsstrahlung beams above neutron emission threshold, from a 20 MeV pulsed electron linac, have also been used to produce residual nuclei in excited states via photonuclear reactions allowing the detection of heavy elements via their characteristic γ-rays. This can be developed into a technique to trace some heavy metals in large rocks and soils for environmental applications.

  15. Optimal design of Anger camera for bremsstrahlung imaging: Monte Carlo evaluation.

    Directory of Open Access Journals (Sweden)

    Stephan eWalrand

    2014-06-01

    Full Text Available A conventional Anger camera is not adapted to bremsstrahlung imaging and, as a result, even using a reduced energy acquisition window, geometric x-rays represent less than 15% of the recorded events. This increases noise, limits the contrast, and reduces the quantification accuracy.Monte Carlo simulations of energy spectra showed that a camera based on a 30mm-thick BGO crystal and equipped with a high energy pinhole collimator is well adapted to bremsstrahlung imaging. The total scatter contamination is reduced by a factor ten versus a conventional NaI camera equipped with a high energy parallel hole collimator enabling acquisition using an extended energy window ranging from 50 to 350 keV. By using the recorded event energy in the reconstruction method, shorter acquisition time and reduced orbit range will be usable allowing the design of a simplified mobile gantry. This is more convenient for use in a busy catheterization room. After injecting a safe activity, a fast SPECT could be performed without moving the catheter tip in order to assess the liver dosimetry and estimate the additional safe activity that could still be injected.Further long running time Monte Carlo simulations of realistic acquisitions will allow assessing the quantification capability of such system. Simultaneously, a dedicated bremsstrahlung prototype camera reusing PMT-BGO blocks coming from a retired PET system is currently under design for further evaluation.

  16. Integrated Bayesian Estimation of Zeff in the TEXTOR Tokamak from Bremsstrahlung and CX Impurity Density Measurements

    Science.gov (United States)

    Verdoolaege, G.; Von Hellermann, M. G.; Jaspers, R.; Ichir, M. M.; Van Oost, G.

    2006-11-01

    The validation of diagnostic date from a nuclear fusion experiment is an important issue. The concept of an Integrated Data Analysis (IDA) allows the consistent estimation of plasma parameters from heterogeneous data sets. Here, the determination of the ion effective charge (Zeff) is considered. Several diagnostic methods exist for the determination of Zeff, but the results are in general not in agreement. In this work, the problem of Zeff estimation on the TEXTOR tokamak is approached from the perspective of IDA, in the framework of Bayesian probability theory. The ultimate goal is the estimation of a full Zeff profile that is consistent both with measured bremsstrahlung emissivities, as well as individual impurity spectral line intensities obtained from Charge Exchange Recombination Spectroscopy (CXRS). We present an overview of the various uncertainties that enter the calculation of a Zeff profile from bremsstrahlung date on the one hand, and line intensity data on the other hand. We discuss a simple linear and nonlinear Bayesian model permitting the estimation of a central value for Zeff and the electron density ne on TEXTOR from bremsstrahlung emissivity measurements in the visible, and carbon densities derived from CXRS. Both the central Zeff and ne are sampled using an MCMC algorithm. An outlook is given towards possible model improvements.

  17. MAGNET

    CERN Multimedia

    by B. Curé

    2011-01-01

    The magnet operation was very satisfactory till the technical stop at the end of the year 2010. The field was ramped down on 5th December 2010, following the successful regeneration test of the turbine filters at full field on 3rd December 2010. This will limit in the future the quantity of magnet cycles, as it is no longer necessary to ramp down the magnet for this type of intervention. This is made possible by the use of the spare liquid Helium volume to cool the magnet while turbines 1 and 2 are stopped, leaving only the third turbine in operation. This obviously requires full availability of the operators to supervise the operation, as it is not automated. The cryogenics was stopped on 6th December 2010 and the magnet was left without cooling until 18th January 2011, when the cryoplant operation resumed. The magnet temperature reached 93 K. The maintenance of the vacuum pumping was done immediately after the magnet stop, when the magnet was still at very low temperature. Only the vacuum pumping of the ma...

  18. MAGNET

    CERN Multimedia

    Benoit Curé

    2010-01-01

    Operation of the magnet has gone quite smoothly during the first half of this year. The magnet has been at 4.5K for the full period since January. There was an unplanned short stop due to the CERN-wide power outage on May 28th, which caused a slow dump of the magnet. Since this occurred just before a planned technical stop of the LHC, during which access in the experimental cavern was authorized, it was decided to leave the magnet OFF until 2nd June, when magnet was ramped up again to 3.8T. The magnet system experienced a fault also resulting in a slow dump on April 14th. This was triggered by a thermostat on a filter choke in the 20kA DC power converter. The threshold of this thermostat is 65°C. However, no variation in the water-cooling flow rate or temperature was observed. Vibration may have been the root cause of the fault. All the thermostats have been checked, together with the cables, connectors and the read out card. The tightening of the inductance fixations has also been checked. More tem...

  19. MAGNET

    CERN Multimedia

    B. Curé

    2012-01-01

      Following the unexpected magnet stops last August due to sequences of unfortunate events on the services and cryogenics [see CMS internal report], a few more events and initiatives again disrupted the magnet operation. All the magnet parameters stayed at their nominal values during this period without any fault or alarm on the magnet control and safety systems. The magnet was stopped for the September technical stop to allow interventions in the experimental cavern on the detector services. On 1 October, to prepare the transfer of the liquid nitrogen tank on its new location, several control cables had to be removed. One cable was cut mistakenly, causing a digital input card to switch off, resulting in a cold-box (CB) stop. This tank is used for the pre-cooling of the magnet from room temperature down to 80 K, and for this reason it is controlled through the cryogenics control system. Since the connection of the CB was only allowed for a field below 2 T to avoid the risk of triggering a fast d...

  20. MAGNET

    CERN Multimedia

    B. Curé

    2012-01-01

      The magnet was energised at the beginning of March 2012 at a low current to check all the MSS safety chains. Then the magnet was ramped up to 3.8 T on 6 March 2012. Unfortunately two days later an unintentional switch OFF of the power converter caused a slow dump. This was due to a misunderstanding of the CCC (CERN Control Centre) concerning the procedure to apply for the CMS converter control according to the beam-mode status at that time. Following this event, the third one since 2009, a discussion was initiated to define possible improvement, not only on software and procedures in the CCC, but also to evaluate the possibility to upgrade the CMS hardware to prevent such discharge from occurring because of incorrect procedure implementations. The magnet operation itself was smooth, and no power cuts took place. As a result, the number of magnetic cycles was reduced to the minimum, with only two full magnetic cycles from 0 T to 3.8 T. Nevertheless the magnet suffered four stops of the cryogeni...

  1. The synergistic effect of bremsstrahlung photons and intense laser radiation on the structural properties of carbon nanotubes

    International Nuclear Information System (INIS)

    We present in this paper the influence of a synergistic radiation effect of both bremsstrahlung photons with maximum energy of 60 MeV and intense laser radiation (up to 60 KW cm−2) on the structural properties of carbon nanotubes (CNTs). The defect formation (damage) in CNTs under separate irradiations of 60 MeV bremsstrahlung photon or intense laser and their combined irradiations has been investigated by Raman spectroscopy. The experimental results show that (i) our obtained natural CNTs are multi-walled carbon nanotubes (MWCNTs) with a large number of structural defects, which are non-nanotube carbon impurities; (ii) the MWCNTs were not damaged by the irradiations of an intense laser and a bremsstrahlung photon beam with low electron fluency and the irradiation even leads to more purification/ordering; (iii) the reversible modification in non-irradiated and 60 MeV bremsstrahlung photon irradiated MWCNTs with variation of laser power density (LPD) have been received; (iv) the influence on the structural properties of MWCNTs induced by the combined irradiation was greater than the separate irradiation of a 60 MeV bremsstrahlung photon or intense laser radiation. The result also demonstrates that micro-Raman spectroscopy is a valuable, fast and non-destructive tool for the investigation of purification/ordering of CNTs

  2. Dynamical structure of magnetized dissipative accretion flow around black holes

    OpenAIRE

    Sarkar, Biplob; Das, Santabrata

    2016-01-01

    We study the global structure of optically thin, advection dominated, magnetized accretion flow around black holes. We consider the magnetic field to be turbulent in nature and dominated by the toroidal component. With this, we obtain the complete set of accretion solutions for dissipative flows where bremsstrahlung process is regarded as the dominant cooling mechanism. We show that rotating magnetized accretion flow experiences virtual barrier around black hole due to centrifugal repulsion t...

  3. On the bremsstrahlung background correction to the high-energy Compton spectroscopy

    Indian Academy of Sciences (India)

    S Mathur; B L Ahuja

    2005-07-01

    A methodology for bremsstrahlung (BS) background correction to extract a true Compton profile in high-energy Compton scattering experiments is presented. The BS background profiles for Hg, computed within the Born approximation, are estimated for different values of incident energy. It is seen for the first time that the BS background contribution in high-energy Compton profile experiments like those employing third generation synchrotron radiation sources comes out to be significant and non-linear. Further, it is found that the incorporation of BS correction in data reduction of such an experiment performed on Hg at 662 keV energy helps in reconciliation of theory and experiment.

  4. Pion mass effects on axion emission from neutron stars through NN bremsstrahlung processes

    International Nuclear Information System (INIS)

    The rates of axion emission by nucleon-nucleon bremsstrahlung are calculated with the inclusion of the full momentum contribution from a nuclear one pion exchange (OPE) potential. The contributions of the neutron-neutron (nn), proton-proton ( pp) and neutron-proton (np) processes in both the non-degenerate and degenerate limits are explicitly given. We find that the finite-momentum corrections to the emissivities are quantitatively significant for the non-degenerate regime and temperature-dependent, and should affect the existing axion mass bounds. The trend of these nuclear effects is to diminish the emissivities.

  5. Emerging Hawking-Like Radiation from Gravitational Bremsstrahlung Beyond the Planck Scale

    Science.gov (United States)

    Ciafaloni, Marcello; Colferai, Dimitri; Veneziano, Gabriele

    2015-10-01

    We argue that, as a consequence of the graviton's spin-2, its bremsstrahlung in trans-Planckian-energy (E ≫MP ) gravitational scattering at small deflection angle can be nicely expressed in terms of helicity-transformation phases and their transfer within the scattering process. The resulting spectrum exhibits deeply sub-Planckian characteristic energies of order MP2/E ≪MP (reminiscent of Hawking radiation), a suppressed fragmentation region, and a reduced rapidity plateau, in broad agreement with recent classical estimates.

  6. Emerging Hawking-Like Radiation from Gravitational Bremsstrahlung Beyond the Planck Scale

    CERN Document Server

    Ciafaloni, Marcello; Veneziano, Gabriele

    2015-01-01

    We argue that, as a consequence of the graviton's spin-2, its bremsstrahlung in trans-planckian-energy ($E\\gg M_P$) gravitational scattering at small deflection angle can be nicely expressed in terms of helicity-transformation phases and their transfer within the scattering process. The resulting spectrum exhibits deeply sub-planckian characteristic energies of order $M_P^2/E \\ll M_P$ (reminiscent of Hawking radiation), a suppressed fragmentation region, and a reduced rapidity plateau, in broad agreement with recent classical estimates.

  7. Monte Carlo 20 and 45 MeV Bremsstrahlung and dose-reduction calculations

    International Nuclear Information System (INIS)

    The SANDYL electron-photon coupled Monte Carlo code has been compared with previously published experimental bremsstrahlung data at 20.9 MeV electron energy. The code was then used to calculate forward-directed spectra, angular distributions and dose-reduction factors for three practical configurations. These are: 20 MeV electrons incident on 1 mm of W + 59 mm of Be, 45 MeV electrons of 1 mm of W and 45 MeV electrons on 1 mm of W + 147 mm of Be. The application of these results to flash radiography is discussed. 7 references, 12 figures, 1 table

  8. Interference Peak in the Spectrum of Bremsstrahlung on Two Amorphous Targets

    CERN Document Server

    Bondarenco, M V

    2014-01-01

    We investigate the interference pattern in the spectrum of non-dipole bremsstrahlung on two amorphous foils. Apart from suppression at lowest $\\omega$, the spectrum exhibits an enhancement adjacent to it. In classical electrodynamics, the net effect of suppression and enhancement proves to be zero. We study the location and the origin of the spectral features, comparing predictions of full Moli\\`ere averaging with those of the Gaussian averaging with Coulomb corrections to the rms multiple scattering angle. Comparison with experimental data, and with previous theoretical predictions is presented.

  9. Inverse bremsstrahlung stabilization of noise in the generation of ultrashort intense pulses by backward Raman amplification

    International Nuclear Information System (INIS)

    Inverse bremsstrahlung absorption of the pump laser beam in a backward Raman amplifier over the round-trip light transit time through the subcritical density plasma can more than double the electron temperature of the plasma and produce time-varying axial temperature gradients. The resulting increased Landau damping of the plasma wave and detuning of the resonance can act to stabilize the pump against unwanted amplification of Langmuir noise without disrupting nonlinear amplification of the femtosecond seed pulse. Because the heating rate increases with the charge state Z, only low-Z plasmas (hydrogen, helium, or helium-hydrogen mixtures) will maintain a low enough temperature for efficient operation

  10. Virtual- and bremsstrahlung corrections to b -> d l+ l- in the standard model

    OpenAIRE

    Asatrian, H. M.; Bieri, K.; Greub, C.; M. Walker

    2003-01-01

    We present the calculation of the virtual- and bremsstrahlung corrections of O(alpha_s) to the matrix elements . This is the missing piece in the NNLL results for various observables associated with the process B-> X_d l+ l-, like the branching ratio, the CP-rate asymmetry and the forward-backward asymmetry. This paper is an extension of analogous calculations done by some of us for the process B-> X_s l+ l-. As the contributions of the diagrams induced by the operators O_1^u and O_2^u with a...

  11. High-power vircator in the regime of warm bremsstrahlung X-ray pulses generation

    International Nuclear Information System (INIS)

    The article presents the results of 2D self-consistent calculations of electron beam dynamics in vircator cell alongside with the resulting spectra of the accompanying microwave radiation. Also presented are the results of 1D calculations of electron beam dynamics with consideration for dissipation at the anode foil alongside with the resulting spectra of X-ray radiation. Being presented are the results of the first experiments aimed at investigation of bremsstrahlung X-ray radiation of the vircator for thin (10 μm, Ta) and thick (100 μm, Ta) anode foil

  12. MAGNET

    CERN Multimedia

    B. Curé

    2012-01-01

      The magnet and its sub-systems were stopped at the beginning of the winter shutdown on 8th December 2011. The magnet was left without cooling during the cryogenics maintenance until 17th January 2012, when the cryoplant operation resumed. The magnet temperature reached 93 K. The vacuum pumping was maintained during this period. During this shutdown, the yearly maintenance was performed on the cryogenics, the vacuum pumps, the magnet control and safety systems, and the power converter and discharge lines. Several preventive actions led to the replacement of the electrovalve command coils, and the 20A DC power supplies of the magnet control system. The filters were cleaned on the demineralised water circuits. The oil of the diffusion pumps was changed. On the cryogenics, warm nitrogen at 343 K was circulated in the cold box to regenerate the filters and the heat exchangers. The coalescing filters have been replaced at the inlet of both the turbines and the lubricant trapping unit. The active cha...

  13. MAGNET

    CERN Multimedia

    Benoit Curé

    2010-01-01

    The magnet was successfully operated at the end of the year 2009 despite some technical problems on the cryogenics. The magnet was ramped up to 3.8 T at the end of November until December 16th when the shutdown started. The magnet operation met a few unexpected stops. The field was reduced to 3.5 T for about 5 hours on December 3rd due to a faulty pressure sensor on the helium compressor. The following day the CERN CCC stopped unintentionally the power converters of the LHC and the experiments, triggering a ramp down that was stopped at 2.7 T. The magnet was back at 3.8 T about 6 hours after CCC sent the CERN-wide command. Three days later, a slow dump was triggered due to a stop of the pump feeding the power converter water-cooling circuit, during an intervention on the water-cooling plant done after several disturbances on the electrical distribution network. The magnet was back at 3.8 T in the evening the same day. On December 10th a break occurred in one turbine of the cold box producing the liquid ...

  14. MAGNET

    CERN Multimedia

    B. Curé

    2011-01-01

    The CMS magnet has been running steadily and smoothly since the summer, with no detected flaw. The magnet instrumentation is entirely operational and all the parameters are at their nominal values. Three power cuts on the electrical network affected the magnet run in the past five months, with no impact on the data-taking as the accelerator was also affected at the same time. On 22nd June, a thunderstorm caused a power glitch on the service electrical network. The primary water cooling at Point 5 was stopped. Despite a quick restart of the water cooling, the inlet temperature of the demineralised water on the busbar cooling circuit increased by 5 °C, up to 23.3 °C. It was kept below the threshold of 27 °C by switching off other cooling circuits to avoid the trigger of a slow dump of the magnet. The cold box of the cryogenics also stopped. Part of the spare liquid helium volume was used to maintain the cooling of the magnet at 4.5 K. The operators of the cryogenics quickly restarted ...

  15. MAGNET

    CERN Multimedia

    B. Curé

    2013-01-01

      The magnet was operated without any problem until the end of the LHC run in February 2013, apart from a CERN-wide power glitch on 10 January 2013 that affected the CMS refrigerator, causing a ramp down to 2 T in order to reconnect the coldbox. Another CERN-wide power glitch on 15 January 2013 didn’t affect the magnet subsystems, the cryoplant or the power converter. At the end of the magnet run, the reconnection of the coldbox at 2.5 T was tested. The process will be updated, in particular the parameters of some PID valve controllers. The helium flow of the current leads was reduced but only for a few seconds. The exercise will be repeated with the revised parameters to validate the automatic reconnection process of the coldbox. During LS1, the water-cooling services will be reduced and many interventions are planned on the electrical services. Therefore, the magnet cryogenics and subsystems will be stopped for several months, and the magnet cannot be kept cold. In order to avoid unc...

  16. MAGNETS

    Science.gov (United States)

    Hofacker, H.B.

    1958-09-23

    This patent relates to nmgnets used in a calutron and more particularly to means fur clamping an assembly of magnet coils and coil spacers into tightly assembled relation in a fluid-tight vessel. The magnet comprises windings made up of an assembly of alternate pan-cake type coils and spacers disposed in a fluid-tight vessel. At one end of the tank a plurality of clamping strips are held firmly against the assembly by adjustable bolts extending through the adjacent wall. The foregoing arrangement permits taking up any looseness which may develop in the assembly of coils and spacers.

  17. Neutron–proton bremsstrahlung as a possible probe of high-momentum component in nucleon momentum distribution

    Directory of Open Access Journals (Sweden)

    Hui Xue

    2016-04-01

    Full Text Available Neutron-proton bremsstrahlung in intermediate energy nucleus–nucleus collisions is proposed as a possible probe to study the high-momentum component in nucleon momentum distribution of finite nucleus. Based on the Boltzmann–Uehling–Uhlenbeck (BUU transport model, the effects of high-momentum component on the production of bremsstrahlung photons in the reaction of C12+12C collisions at different incident beam energies are studied. It is found that the high-momentum component increases the high-energy bremsstrahlung photon production remarkably. Furthermore, the ratio of photon production at different incident beam energies is suggested as a potential observable to probe the high-momentum component in nucleon momentum distribution of finite nucleus.

  18. MAGNET

    CERN Multimedia

    B. Curé

    2011-01-01

    The magnet ran smoothly in the last few months until a fast dump occurred on 9th May 2011. Fortunately, this occurred in the afternoon of the first day of the technical stop. The fast dump was due to a valve position controller that caused the sudden closure of a valve. This valve is used to regulate the helium flow on one of the two current leads, which electrically connects the coil at 4.5 K to the busbars at room temperature. With no helium flow on the lead, the voltage drop and the temperatures across the leads increase up to the defined thresholds, triggering a fast dump through the Magnet Safety System (MSS). The automatic reaction triggered by the MSS worked properly. The helium release was limited as the pressure rise was just at the limit of the safety valve opening pressure. The average temperature of the magnet reached 72 K. It took four days to recover the temperature and refill the helium volumes. The faulty valve controller was replaced by a spare one before the magnet ramp-up resumed....

  19. Experimental investigation of synchrotron and Bremsstrahlung hazards at lithography beam line of Indus-2 SRS

    International Nuclear Information System (INIS)

    Radiation hazard at synchrotron radiation (SR) beam lines of Indus-2 Synchrotron Radiation Source (SRS) consists of synchrotron radiation (SR) and Bremsstrahlung radiation (BR). These hazards were quantified experimentally in Lithography beam line (BL-07) of Indus-2 SRS. Measurement was performed during the initial trial operation of the beam line. Transmission of SR through the beam line was optimized by providing bump to the electron beam, prior to the measurement. Thin window ion chamber was used for the SR measurement in the direct beam. Ion current obtained is converted to exposure rate using a calibration factor obtained w.r.t. 60Co source. Copper absorber of 6 mm thick was used for eliminating SR contribution during BR dose measurement. The exposure rates obtained are 3.83E05 R/h-mA and 0.042 R/h-mA for SR and BR respectively. Energy of Bremsstrahlung radiation was also experimentally evaluated using attenuation technique. Details of these measurement and results are presented in this paper. (author)

  20. Photoactivation of the p-nucleus {sup 92}Mo with bremsstrahlung at ELBE

    Energy Technology Data Exchange (ETDEWEB)

    Erhard, M; Grosse, E; Junghans, A R; Klug, J; Nair, C; Rusev, G; Schilling, K D; Schwengner, R; Wagner, A, E-mail: erhard@pd.infn.i [Institut f. Strahlenphysik, Forschungszentrum Dresden-Rossendorf, 01314 Dresden (Germany)

    2010-01-01

    In nuclear network calculations especially the p-nucleus {sup 92}Mo is frequently underproduced. Since experimental data of the photodisintegration of {sup 92}Mo so far do not exist, it was necessary to measure the reaction yields with the photoactivation method using the brems-strahlung facility ELBE at FZ Dresden-Rossendorf. Also the reaction {sup 100}Mo({gamma},n) could be tested while irradiating Mo samples of natural composition. The photon fluence was measured with nuclear resonance fluorescence (NRF) of strong and well-known transitions in {sup 11}B. As a normalization standard the photoactivation reaction {sup 197}Au({gamma},n) was used. For the 65 s half-life of {sup 91m}Mo a fast pneumatic delivery was used. The photoactivation yields of the ({gamma},p) and ({gamma},n) reactions are compared to yield integrals of the bremsstrahlung spectral shape folded with the cross sections derived from Hauser-Feshbach nuclear model calculations using the TALYS program and cross sections from earlier experiments.

  1. Photoactivation of the p-nucleus 92Mo with bremsstrahlung at ELBE

    Science.gov (United States)

    Erhard, M.; Grosse, E.; Junghans, A. R.; Klug, J.; Nair, C.; Rusev, G.; Schilling, K. D.; Schwengner, R.; Wagner, A.

    2010-01-01

    In nuclear network calculations especially the p-nucleus 92Mo is frequently underproduced. Since experimental data of the photodisintegration of 92Mo so far do not exist, it was necessary to measure the reaction yields with the photoactivation method using the brems-strahlung facility ELBE at FZ Dresden-Rossendorf. Also the reaction 100Mo(γ,n) could be tested while irradiating Mo samples of natural composition. The photon fluence was measured with nuclear resonance fluorescence (NRF) of strong and well-known transitions in 11B. As a normalization standard the photoactivation reaction 197Au(γ,n) was used. For the 65 s half-life of 91mMo a fast pneumatic delivery was used. The photoactivation yields of the (γ,p) and (γ,n) reactions are compared to yield integrals of the bremsstrahlung spectral shape folded with the cross sections derived from Hauser-Feshbach nuclear model calculations using the TALYS program and cross sections from earlier experiments.

  2. Effect of degenerate particles on internal bremsstrahlung of Majorana dark matter

    Science.gov (United States)

    Okada, Hiroshi; Toma, Takashi

    2015-11-01

    Gamma-rays induced by annihilation or decay of dark matter can be its smoking gun signature. In particular, gamma-rays generated by internal bremsstrahlung of Majorana and real scalar dark matter is promising since it can be a leading emission of sharp gamma-rays. However in the case of Majorana dark matter, its cross section for internal bremsstrahlung cannot be large enough to be observed by future gamma-ray experiments if the observed relic density is assumed to be thermally produced. In this paper, we introduce some degenerate particles with Majorana dark matter, and show they lead enhancement of the cross section. As a result, increase of about one order of magnitude for the cross section is possible without conflict with the observed relic density, and it would be tested by the future gamma-ray experiments such as GAMMA-400 and Cherenkov Telescope Array (CTA). In addition, the constraints of perturbativity, positron observation by the AMS experiment and direct search for dark matter are discussed.

  3. Bremsstrahlung from nuclear scattering at low energy near a resonance. Final report

    International Nuclear Information System (INIS)

    The understanding of almost all low-energy reaction processes depends upon a distorted wave Born approximation (DWBA) analysis. DWBA procedures, in turn, depend crucially upon a correct optical model description of the projectile-target elastic scattering process. An assumption that the potential is local together with measurements of the elastic scattering data at all energies (0 -infinity) would completely determine that potential, including its off-shell or short-range properties. However, one does not have the luxury of knowing the elastic scattering phase shifts for all energies nor are we so naive as to believe that the potential is completely local. Thus, an alternative approach is called for. The present proposal describes a program to contribute to the general understanding of nuclear reactions by determining as many of the off-shell properties of the proton-nucleus interaction as possible through the study of the proton-nucleus bremsstrahlung process. We seek to establish the limits of validity of a model independent analysis of these reactions in the neighborhood of a resonance or a breakup threshold, and to utilize the differences between this analysis and the data to elucidate those off-shell constraints which any valid proton-nucleus model interaction must satisfy. The bremsstrahlung process provides a method for determining the off-shell properties of the proton-nucleus potential, and the Brooklyn College program offers a unique opportunity to measure these crucial aspects of the low energy proton-nucleus interaction. 18 references

  4. Bremsstrahlung-induced highly penetrating probes for nondestructive assay and defect analysis

    CERN Document Server

    Selim, F A; Harmon, J F; Kwofie, J; Spaulding, R; Erickson, G; Roney, T

    2002-01-01

    Nondestructive assay and defect analysis probes based on bremsstrahlung-induced processes have been developed to identify elements and probe defects in large volume samples. Bremsstrahlung beams from (electron accelerators) with end-point energies both above and below neutron emission threshold have been used. Below neutron emission threshold these beams (from 6 MeV small pulsed linacs), which exhibit high penetration, create positrons via pair production inside the material and produce X-ray fluorescence (XRF) radiation. Chemical assays of heavy elements in thick samples up to 10 g/cm sup 2 thick are provided by energy dispersive XRF measurements. The pair-produced positrons annihilate within the material, thereby emitting 511 keV gamma radiation. Doppler broadening spectroscopy of the 511 keV radiation can be performed to characterize the material and measure defects in samples of any desired thickness. This technique has successfully measured induced strain due to tensile stress in steel samples of 0.64 cm...

  5. Limits for an inverse bremsstrahlung origin of the diffuse Galactic soft gamma-ray emission

    DEFF Research Database (Denmark)

    Pohl, M.

    1998-01-01

    RXTE, GINGA, and OSSE observations have revealed an intense low-energy gamma-ray continuum emission from the Galactic plane, which is commonly interpreted as evidence for the possible existence of a strong flux of low-energy cosmic ray electrons. In this Paper I discuss the scenario of a hadronic...... origin of the soft Galactic gamma-ray continuum through inverse bremsstrahlung. A flux of low-energy cosmic rays strong enough to produce the observed spectrum of gamma-rays implies substantial gamma-ray emission at a few MeV through nuclear de-excitation. It is shown that the existing limits on excess 3......-7 MeV emission from the Galactic plane, in concert with the constraints from pi(0)-decay gamma-ray emission at higher energies, are in serious conflict with an inverse bremsstrahlung origin of the Galactic soft gamma-ray emission for any physically plausible low-energy cosmic ray spectrum. While...

  6. A high-power vircator operating as an X-ray bremsstrahlung generator

    International Nuclear Information System (INIS)

    A vircator capable of generating high-power X-ray pulses due to the multiple transitions of electrons through a thin anode foil transparent to X radiation has been created and put into operation for the first time. The vircator is created on the basis of a direct-action electron accelerator supplied from an inductive energy storage operating with a plasma opening switch. Self-consistent two-dimensional simulations of the electron beam dynamics in the vircator chamber are performed, and the spectra of the generated microwave radiation are determined. Self-consistent one-dimensional simulations of the beam dynamics with allowance for electron scattering in the foil were also carried out, and the X-ray bremsstrahlung spectra were measured. Results are presented from the first experiments on the generation of X-ray bremsstrahlung in vircators with thin (10 μm) and thick (100 μm) tantalum anode foils. For a thin foil, the X-ray (Eγ > 30 keV) dose is eight times as high as that for a thick foil and the average photon energy is 30 keV (against 80 keV for a thick foil)

  7. MAGNET

    CERN Multimedia

    B. Curé

    MAGNET During the winter shutdown, the magnet subsystems went through a full maintenance. The magnet was successfully warmed up to room temperature beginning of December 2008. The vacuum was broken later on by injecting nitrogen at a pressure just above one atmosphere inside the vacuum tank. This was necessary both to prevent any accidental humidity ingress, and to allow for a modification of the vacuum gauges on the vacuum tank and maintenance of the diffusion pumps. The vacuum gauges had to be changed, because of erratic variations on the measurements, causing spurious alarms. The new type of vacuum gauges has been used in similar conditions on the other LHC experiments and without problems. They are shielded against the stray field. The lubricants of the primary and diffusion pumps have been changed. Several minor modifications were also carried out on the equipment in the service cavern, with the aim to ease the maintenance and to allow possible intervention during operation. Spare sensors have been bough...

  8. MAGNET

    CERN Multimedia

    Benoit Curé

    2010-01-01

    The magnet worked very well at 3.8 T as expected, despite a technical issue that manifested twice in the cryogenics since June. All the other magnet sub-systems worked without flaw. The issue in the cryogenics was with the cold box: it could be observed that the cold box was getting progressively blocked, due to some residual humidity and air accumulating in the first thermal exchanger and in the adsorber at 65 K. This was later confirmed by the analysis during the regeneration phases. An increase in the temperature difference between the helium inlet and outlet across the heat exchanger and a pressure drop increase on the filter of the adsorber were observed. The consequence was a reduction of the helium flow, first compensated by the automatic opening of the regulation valves. But once they were fully opened, the flow and refrigeration power reduced as a consequence. In such a situation, the liquid helium level in the helium Dewar decreased, eventually causing a ramp down of the magnet current and a field...

  9. MAGNET

    CERN Multimedia

    Benoit Curé.

    The magnet operation restarted end of June this year. Quick routine checks of the magnet sub-systems were performed at low current before starting the ramps up to higher field. It appeared clearly that the end of the field ramp down to zero was too long to be compatible with the detector commissioning and operations plans. It was decided to perform an upgrade to keep the ramp down from 3.8T to zero within 4 hours. On July 10th, when a field of 1.5T was reached, small movements were observed in the forward region support table and it was decided to fix this problem before going to higher field. At the end of July the ramps could be resumed. On July 28th, the field was at 3.8T and the summer CRAFT exercise could start. This run in August went smoothly until a general CERN wide power cut took place on August 3rd, due to an insulation fault on the high voltage network outside point 5. It affected the magnet powering electrical circuit, as it caused the opening of the main circuit breakers, resulting in a fast du...

  10. MAGNET

    CERN Multimedia

    B. Curé

    2013-01-01

    The magnet is fully stopped and at room temperature. The maintenance works and consolidation activities on the magnet sub-systems are progressing. To consolidate the cryogenic installation, two redundant helium compressors will be installed as ‘hot spares’, to avoid the risk of a magnet downtime in case of a major failure of a compressor unit during operation. The screw compressors, their motors, the mechanical couplings and the concrete blocks are already available and stored at P5. The metallic structure used to access the existing compressors in SH5 will be modified to allow the installation of the two redundant ones. The plan is to finish the installation and commissioning of the hot spare compressors before the summer 2014. In the meantime, a bypass on the high-pressure helium piping will be installed for the connection of a helium drier unit later during the Long Shutdown 1, keeping this installation out of the schedule critical path. A proposal is now being prepared for the con...

  11. Secondary bremsstrahlung and the energy-conservation aspects of kerma in photon-irradiated media

    Science.gov (United States)

    Kumar, Sudhir; Nahum, Alan E.

    2016-02-01

    Kerma, collision kerma and absorbed dose in media irradiated by megavoltage photons are analysed with respect to energy conservation. The user-code DOSRZnrc was employed to compute absorbed dose D, kerma K and a special form of kerma, K ncpt, obtained by setting the charged-particle transport energy cut-off very high, thereby preventing the generation of ‘secondary bremsstrahlung’ along the charged-particle paths. The user-code FLURZnrc was employed to compute photon fluence, differential in energy, from which collision kerma, K col and K were derived. The ratios K/D, K ncpt/D and K col/D have thereby been determined over a very large volumes of water, aluminium and copper irradiated by broad, parallel beams of 0.1 to 25 MeV monoenergetic photons, and 6, 10 and 15 MV ‘clinical’ radiotherapy qualities. Concerning depth-dependence, the ‘area under the kerma, K, curve’ exceeded that under the dose curve, demonstrating that kerma does not conserve energy when computed over a large volume. This is due to the ‘double counting’ of the energy of the secondary bremsstrahlung photons, this energy being (implicitly) included in the kerma ‘liberated’ in the irradiated medium, at the same time as this secondary bremsstrahlung is included in the photon fluence which gives rise to kerma elsewhere in the medium. For 25 MeV photons this ‘violation’ amounts to 8.6%, 14.2% and 25.5% in large volumes of water, aluminium and copper respectively but only 0.6% for a ‘clinical’ 6 MV beam in water. By contrast, K col/D and K ncpt/D, also computed over very large phantoms of the same three media, for the same beam qualities, are equal to unity within (very low) statistical uncertainties, demonstrating that collision kerma and the special type of kerma, K ncpt, do conserve energy over a large volume. A comparison of photon fluence spectra for the 25 MeV beam at a depth of  ≈51 g cm-2 for both very high and very low charged-particle transport cut

  12. Estimation of Electron Dose Delivered by a 0.4 MeV Accelerator from Bremsstrahlung Dose Measurements

    DEFF Research Database (Denmark)

    Karadjov, A. G.; Hansen, Jørgen-Walther

    1980-01-01

    Determination of a 0.4 MeV electron dose from a bremsstrahlung dose measurement using a converter-detector system is considered. The detector used is a Frickle dosimeter, and the converters are aluminum, copper and lead foils. Optimal converter thickness is ascertained experimentally for each mat...

  13. MAGNET

    CERN Multimedia

    Benoit Curé

    The magnet subsystems resumed operation early this spring. The vacuum pumping was restarted mid March, and the cryogenic power plant was restarted on March 30th. Three and a half weeks later, the magnet was at 4.5 K. The vacuum pumping system is performing well. One of the newly installed vacuum gauges had to be replaced at the end of the cool-down phase, as the values indicated were not coherent with the other pressure measurements. The correction had to be implemented quickly to be sure no helium leak could be at the origin of this anomaly. The pressure measurements have been stable and coherent since the change. The cryogenics worked well, and the cool-down went quite smoothly, without any particular difficulty. The automated start of the turbines had to be fine-tuned to get a smooth transition, as it was observed that the cooling power delivered by the turbines was slightly higher than needed, causing the cold box to stop automatically. This had no consequence as the cold box safety system acts to keep ...

  14. MAGNET

    CERN Multimedia

    B. Curé

    During the winter shutdown, the magnet subsystems went through a full maintenance. The magnet was successfully warmed up to room temperature beginning of December 2008. The vacuum was broken later on by injecting nitrogen at a pressure just above one atmosphere inside the vacuum tank. This was necessary both to prevent any accidental humidity ingress, and to allow for a modification of the vacuum gauges on the vacuum tank and maintenance of the diffusion pumps. The vacuum gauges had to be changed, because of erratic variations on the measurements, causing spurious alarms. The new type of vacuum gauges has been used in similar conditions on the other LHC experiments and without problems. They are shielded against the stray field. The lubricants of the primary and diffusion pumps have been changed. Several minor modifications were also carried out on the equipment in the service cavern, with the aim to ease the maintenance and to allow possible intervention during operation. Spare sensors have been bought. Th...

  15. Thick-target external-bremsstrahlung spectra of 147Pm and 35S β rays

    Science.gov (United States)

    Dhaliwal, A. S.; Powar, M. S.; Singh, M.

    1993-08-01

    External-bremsstrahlung spectra excited by soft β particles of 147Pm (Emaxβ=225 keV) and 35S (Emaxβ=167 keV) in targets of Al, Cu, Sn, and Pb have been studied. The experimental and theoretical results are compared in terms of the number of photons of energy k per m0c2 per unit photon yield to exclude the uncertainty in the source strength measurement and overcome the inherent inadequacy of the normalization procedure used by earlier workers. The results of present measurements for medium- and high-Z elements show better agreement with the theory of Tseng and Pratt [Phys. Rev. A 3, 1714 (1976)] than with Elwert's corrections [Ann. Phys. (N.Y.) 34, 78 (1939)] to the Bethe-Heitler theory [Proc. R. Soc. London Ser. A 14, 83 (1934)], particularly at the higher-energy ends. However, for low-Z elements, both theories are found to be adequate.

  16. Fermi LAT Search for Internal Bremsstrahlung Signatures from Dark Matter Annihilation

    CERN Document Server

    Bringmann, Torsten; Ibarra, Alejandro; Vogl, Stefan; Weniger, Christoph

    2012-01-01

    A commonly encountered obstacle in indirect searches for galactic dark matter is how to disentangle possible signals from astrophysical backgrounds. Given that such signals are most likely subdominant, the search for pronounced spectral features plays a key role for indirect detection experiments; monochromatic gamma-ray lines or similar features related to internal bremsstrahlung, in particular, provide smoking gun signatures. We perform a dedicated search for the latter in the data taken by the Fermi gamma-ray space telescope during its first 43 months. To this end, we use a new adaptive procedure to select optimal target regions that takes into account both standard and contracted dark matter profiles. The behaviour of our statistical method is tested by a bootstrap analysis of the full sky data and found to reproduce the theoretical expectations very well. The limits on the dark matter annihilation cross-section that we derive are stronger than what can be obtained from the observation of dwarf galaxies a...

  17. The Efficiency of Gravitational Bremsstrahlung Production in the Collision of Two Schwarzschild Black Holes

    CERN Document Server

    Aranha, R F; Soares, I Damião; Tonini, E V

    2008-01-01

    We examine the efficiency of gravitational bremsstrahlung production in the process of head-on collision of two boosted Schwarzschild black holes. We constructed initial data for the characteristic initial value problem in Robinson-Trautman spacetimes, that represent two instantaneously stationary Schwarzschild black holes in motion towards each other with the same velocity. The Robinson-Trautman equation was integrated for these initial data using a numerical code based on the Galerkin method. The final resulting configuration is a boosted black hole with Bondi mass greater than the sum of the individual mass of each initial black hole. Two relevant aspects of the process are presented. The first relates the efficiency $\\Delta$ of the energy extraction by gravitational wave emission to the mass of the final black hole. This relation is fitted by a distribution function of non-extensive thermostatistics with entropic parameter $q \\simeq 1/2$; the result extends and validates analysis based on the linearized t...

  18. Observation of intense radiation during thunderstorm and Monte Carlo simulation of bremsstrahlung generation

    International Nuclear Information System (INIS)

    Following Wilson's suggestion of electron acceleration by the electric fields in thunderclouds, a number of experiments were attempted to investigate whether or not energetic electrons and bremsstrahlung X-rays were generated by thunderstorm electric fields or lightning discharge processes. In recent years, enhanced radiation at high altitude has been detected in experiments using scintillation detectors on a jet and an artificial satellite, demonstrating that radiation is indeed associated with lightning activities. However there are few experimental reports of detection near the ground since Whitmire's investigation using thermoluminescent dosimeters (TLDs) in 1979. In winter, many thunderstorms occur on the west coast of Japan, and it has been suggested that gamma-ray dose may increase occasionally during winter thunderstorms. Recently, a gamma-ray dose enhancement which might be caused by the lightning activity was measured by TLDs and environmental radiation monitors around the site of the fast breeder reactor 'Monju', a nuclear power plant facing the Japan Sea. (author)

  19. Spatially resolved hard X-ray polarization in solar flares: effects of Compton scattering and bremsstrahlung

    CERN Document Server

    Jeffrey, Natasha

    2011-01-01

    This paper aims to study the polarization of hard X-ray (HXR) sources in the solar atmosphere, including Compton backscattering of photons in the photosphere (the albedo effect) and the spatial distribution of polarization across the source. HXR photon polarization and spectra produced via electron-ion bremsstrahlung are calculated from electron distributions typical for solar flares. Compton scattering and photoelectric absorption are then modelled using Monte Carlo simulations of photon transport in the photosphere. Polarization maps across HXR sources (primary and albedo components) for each of the modelled electron distributions are calculated at various source locations from the solar centre to the limb. We show that Compton scattering produces a distinct polarization variation across the albedo patch at peak albedo energies of 20-50 keV for all anisotropies modelled. The results show that there are distinct spatial polarization changes in both the radial and perpendicular to radial directions across the...

  20. Search for a 17 keV neutrino in the internal bremsstrahlung spectrum of 125I

    International Nuclear Information System (INIS)

    We have searched for evidence of the emission of a 17 keV neutrino in the internal bremsstrahlung (IB) spectrum accompanying the electron capture decay of 125I. The IB spectrum, recorded in a planar Ge detector, has 1.2x106 counts per keV at 17 keV below the 2p end point. We set an upper limit of 0.4% for the admixture of a 17 keV neutrino, at the 90% confidence level, and exclude a 0.8% admixture at the 99.6% confidence level. The QEC value is found to be 185.77±0.06 keV. We also find that the recent calculations of Suric et al., which employ relativistic self-consistent-field atomic wave functions, reproduce the shape and relative intensity of IB partial spectra within a few percent

  1. Study of the inner Bremsstrahlung following the electron-capture decay of 193 Pt

    International Nuclear Information System (INIS)

    We are measuring the inner Bremsstrahlung (I B) photons emitted in some of the electron-capture decays of 193 Pt. The source was prepared with highly pure metal Pt. It was irradiated with neutron for 52 days and let to cool down for eight months. The remaining activities were due to 193 Ptg (half-life 50 yr) and 192 Ir (half-life 74 d), the latter coming from (n, γ) reactions on a small content of Ir. We have used a radiochemistry method to reduce the Ir content of the source. The resulting Pt compound will be dissolved in a plastic scintillator disk. Most of the 192 Ir decays are β- and their signal in the plastic will be used as a veto for the I B-photon detector. We have performed simulations of the efficiency and absorption effects in the detection geometry. (author)

  2. On the formation of bremsstrahlung in an absorptive QED/QCD medium

    CERN Document Server

    Bluhm, Marcus; Gousset, Thierry; Aichelin, Joerg

    2012-01-01

    The radiative energy loss of a relativistic charge in a dense, absorptive medium can be affected significantly by damping phenomena. The effect is more pronounced for large energies of the charge and/or large damping of the radiation. This can be understood in terms of a competition between the formation time of bremsstrahlung and a damping time scale. Discussing this competition in detail for the absorptive QED and QCD medium, we identify the regions in energy and parameter space, in which either coherence or damping effects are of major importance for the radiation spectrum. We show that damping mechanisms lead to a stronger suppression of the spectrum than coherence effects. This might be visible experimentally in correlations between hadrons at large momenta.

  3. The interference effect of laser-assisted bremsstrahlung emission in Coulumb fields of two nuclei

    CERN Document Server

    Li, Ankang; Ren, Na; Wang, Pingxiao; Zhu, Wenjun; Li, Xiaoya; Hoehn, Ross; Kais, S

    2013-01-01

    In this paper, the spontaneous bremsstrahlung emission from an electron scattered by two fixed nuclei in an intense laser field is investigated in details based upon the Volkov state and the Dirac-Volkov propagator. It has been found that the fundamental harmonic spectrum from the electron radiation exhibits distinctive fringes, which is dependent not only upon the internucleus distance and orientation, but also upon the initial energy of the electron and the laser intensity. By analyzing the differential cross section, we are able to explain these effects in terms of interference among the electron scattering by the nuclei. These results could have promising applications in probing the atomic or molecular dressed potentials in intense laser fields.

  4. Bremsstrahlung x ray spectra of Jupiter and Saturn: Predictions for future planetary spacecraft

    International Nuclear Information System (INIS)

    Calculations of X ray spectra due to bremsstrahlung from precipitating auroral electrons at Jupiter and Saturn are presented. The model assumes that a field-aligned potential drop accelerates a primary beam of electrons into the atmosphere where a population of secondary electrons having a power law energy dependence is generated. The spectrum at Jupiter is normalized to the soft X ray observations of Metzger et al (1983) at the low-energy end and constrained at the high-energy end by UV auroral energy requirements. The spectrum at Saturn is constructed by analogy to the Jovian case allowing for variation of the beam energy, energy flux, and scale size of the Saturnian aurora. The resulting indicate that a significant flux of X rays is emanating from both planets which may serve as a basis for conducting planetary X ray astronomy as part of future spacecraft missions to the planets

  5. 42 MeV bremsstrahlung spectrum analysis by a photoactivation method

    Energy Technology Data Exchange (ETDEWEB)

    Calzado, A.; Vano, E.; Delgado, V.; Gonzalez, L. (Universidad Complutense de Madrid (Spain). Catedra de Fisica Medica; Junta de Energia Nuclear, Madrid (Spain). Inst. de Estudios Nucleares)

    1984-08-01

    The evaluation of 42 MeV, bremsstrahlung spectra from a clinical betatron by using the photoactivation method is described. Photonuclear reactions, mainly of the (..gamma.., n) type, are used as activation detectors. After measurements of photon-induced activities from residual nuclei are performed, the spectral distribution of photons is evaluated by solving the unfolding problem. The latter is carried out through the use of two independent methods, orthonormal expansion and Monte Carlo. In both cases prior conditions to the solution are imposed. Spectra evaluated by both methods and making use of two different size flattening filters are presented. An empirical method to estimate the 'effective' thickness of the Pt target is described.

  6. Groomed jets in heavy-ion collisions: sensitivity to medium-induced bremsstrahlung

    CERN Document Server

    Mehtar-Tani, Yacine

    2016-01-01

    We argue that contemporary jet substructure techniques might facilitate a more direct measurement of hard medium-induced gluon bremsstrahlung in heavy-ion collisions, and focus specifically on the "soft drop declustering" procedure that singles out the two leading jet substructures. Assuming coherent jet energy loss, we find an enhancement of the distribution of the energy fractions shared by the two substructures at small subjet energy caused by hard medium-induced gluon radiation. Departures from this approximation are discussed, in particular, the effects of colour decoherence and the contamination of the grooming procedure by soft background. Finally, we propose a complementary observable, that is the ratio of the two-pronged probability in Pb-Pb to proton-proton collisions and discuss its sensitivity to various energy loss mechanisms.

  7. Study on the dose distribution of 8-MeV bremsstrahlung in mantle field techniques

    International Nuclear Information System (INIS)

    The dose distribution within the patient was studied with 8-MeV bremsstrahlung from a linear accelerator during mantle field irradiation using molded shielding blocks. Doses and dose distributions in the different layers of a modified Alderson phantom were measured by means of film dosimetry and related to the dose in the central ray beam at the middle of the body. Dose distribution within unshielded regions perpendicular to the central ray beam generally being relatively homogeneous, the highest relative doses, amounting to ca. 115%, are found in the region of the mandibular angle and in the supraclavicular region; the dose to superficial lymph nodes at the supraclavicular region reaches 100% of the dose in the central ray beam. As a cause for these important doses near the surface of the body are discussed the extension of mantle fields as well as the increased exit dose of the opposed field and the oblique incidence of radiation. (orig.)

  8. Studies on inner bremsstrahlung from a few β-emitting isotopes

    International Nuclear Information System (INIS)

    Past experimental studies on the inner bremsstrahlung (IB) emission from the forbidden β transitions have shown marked deviations from the theoretical calculations of Lewis and Ford, Ford and Martin, Chang and Falkoff, Madansky and Gebhardt. In this paper we have re-analysed the data of IB emissions from four β-emitting isotopes, namely 89Sr, 141Ce, 111Ag and 99Tc, whose transitions are classified as forbidden. The raw experimental data already available in the literature are critically examined in the light of relevant statistics in order to arrive at meaningful conclusions. The unfolding of the IB spectra was done following the step-by-step procedure of Liden and Starfelt. The results obtained were different from those reported in the literature. (author)

  9. Determination of the anomalous scattering factors of high-Z atoms using bremsstrahlung radiation

    International Nuclear Information System (INIS)

    The anomalous scattering factors (f' and f'') of tungsten, gold and lead atoms have been determined using external bremsstrahlung (EB) photons. The EB photons are produced by the interaction of a beta particle from a beta source with a nickel target. These photons are allowed to pass through thin targets of tungsten, gold and lead. The transmitted photons have been measured by using a GMX-type HPGe detector coupled to an 8K multichannel analyser. The transmitted spectra show a sharp decrease in intensity at the K shell binding energies of the target atoms. The regions around the decreased portion have been used to determine the anomalous scattering factors. The experimentally measured values are compared with the available theoretical values.

  10. Determination of the anomalous scattering factors of high-Z atoms using bremsstrahlung radiation

    Energy Technology Data Exchange (ETDEWEB)

    Hosur, Savita B; Naik, L R; Badiger, N M [Department of Physics, Karnatak University, Dharwad 580003 (India)], E-mail: nagappa123@yahoo.co.in

    2009-02-14

    The anomalous scattering factors (f' and f'') of tungsten, gold and lead atoms have been determined using external bremsstrahlung (EB) photons. The EB photons are produced by the interaction of a beta particle from a beta source with a nickel target. These photons are allowed to pass through thin targets of tungsten, gold and lead. The transmitted photons have been measured by using a GMX-type HPGe detector coupled to an 8K multichannel analyser. The transmitted spectra show a sharp decrease in intensity at the K shell binding energies of the target atoms. The regions around the decreased portion have been used to determine the anomalous scattering factors. The experimentally measured values are compared with the available theoretical values.

  11. New exclusion limits for dark gauge forces from proton Bremsstrahlung in beam-dump data

    Energy Technology Data Exchange (ETDEWEB)

    Bluemlein, Johannes [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany); Brunner, Juergen [Aix-Marseille Univ. CNRS/IN2P3 (France). CPPM

    2013-11-15

    We re-analyze published proton beam dump data taken at the U70 accelerator at IHEP Serpukhov with the {nu}-calorimeter I experiment in 1989 to set mass-coupling limits for dark gauge forces. The corresponding data have been used for axion and light Higgs particle searches before. More recently, limits on dark gauge forces have been derived from this data set, considering a dark photon production from {pi}{sup 0}-decay. Here we determine extended mass and coupling exclusion bounds for dark gauge bosons ranging to masses m{sub {gamma}'} of 624 MeV at admixture parameters {epsilon}{approx_equal}10{sup -6} considering high-energy Bremsstrahlung of the U-boson of the initial proton beam and different detection mechanisms.

  12. Modeling Relativistic Electron Precipitation Bremsstrahlung X-Ray Intensities at 10-100 km Manned Vehicle Altitudes

    Science.gov (United States)

    Krause, L. Habsh; Gilchrist, B. E.; Nishikawa, Ken-Ichi

    2013-01-01

    Relativisitic electron precipitation (REP) events occur when beams or bunches of relativistic electrons of magnetospheric origin enter the Earth's atmosphere, typically at auroral latitudes. REP events are associated with a variety of space weather effects, including production of transitional and bremsstrahlung radiation, catalytic depletion of stratospheric ozone, and scintillation of transionospheric radio waves. This study examines the intensities of x-rays produced at airliner, manned balloon, and space reuseable launch vehicles (sRLVs). The monoenergetic beam is modeled in cylindrical symetry using the paraxial ray equation. Bremsstrahlung photon production is calculated using the traditional Sauter-Elwert cross-section, providing x-ray emission spectra differential in energy and angle. Attenuation is computed for a plane-stratified standard atmosphere, and the loss processes include photoionization, Rayleigh and Compton scattering, electron-positron pair production, and photonuclear interaction. Peak altitudes of electron energy deposition and bremsstrahlung x-ray production were calculated for beams of energies from 1 MeV through 100 MeV. The altitude peak of bremsstrahlung deposition was consistently and significantly lower that that of the electron deposition due to the longer mean free paths of x-rays compared to electrons within the atmosphere. For example, for a nadir-directed monoenergetic 5 MeV beam, the peak deposition altitude was calculated to be 42 km, but the resulting bremsstrahlung deposition peaked at 25 km. This has implications for crew and passenger safety, especially with the growth of the space tourism industry. A survey of results covering the 1-100 MeV spectrum for the three altitude ranges of interest will be presented.

  13. Bremsstrahlung in Mo and Pt targets produced by {sup 90}Sr beta particles in the photon energy region of 1-100 keV

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Amrit; Dhaliwal, A. S., E-mail: dhaliwalas@hotmail.com [Department of Physics, Sant Longowal Institute of Engineering and Technology, Longowal(Sangrur) -148106, Punjab (India)

    2015-08-28

    Bremsstrahlung spectra in thick targets of Mo and Pt, produced by beta emitter {sup 90}Sr (end point energy = 546 keV) have been studied in the photon energy range of 1-100 keV. The experimentally measured bremsstrahlung spectra measured with Si(Li) detector were compared with the theoretical spectral distributions calculated from Elwert corrected (non relativistic) Bethe-Heitler [EBH] theory, modified Elwert factor (relativistic) Bethe-Heitler (F{sub mod}BH) theory for ordinary bremsstrahlung (OB) and the modified Elwert factor (relativistic) Bethe-Heitler (F{sub mod}BH+PB) theory, which includes the polarization bremsstrahlung (PB) into total bremsstrahlung (BS). The present results indicate the correctness of F{sub mod}BH+PB theory in the low energy region, where the contributions of PB into BS are dominant, which is described in terms of stripped atom (SA) approximation. But at the middle and higher energy region of the bremsstrahlung spectrum, where the contribution of PB is negligible, the F{sub mod}BH theory is more close to the experimental results. Hence, it is clear that the production of PB in the low energy region, due to the dynamic response of the target atom suppresses the production of bremsstrahlung at higher energy ends.

  14. Bremsstrahlung in Mo and Pt targets produced by 90Sr beta particles in the photon energy region of 1-100 keV

    Science.gov (United States)

    Singh, Amrit; Dhaliwal, A. S.

    2015-08-01

    Bremsstrahlung spectra in thick targets of Mo and Pt, produced by beta emitter 90Sr (end point energy = 546 keV) have been studied in the photon energy range of 1-100 keV. The experimentally measured bremsstrahlung spectra measured with Si(Li) detector were compared with the theoretical spectral distributions calculated from Elwert corrected (non relativistic) Bethe-Heitler [EBH] theory, modified Elwert factor (relativistic) Bethe-Heitler (FmodBH) theory for ordinary bremsstrahlung (OB) and the modified Elwert factor (relativistic) Bethe-Heitler (FmodBH+PB) theory, which includes the polarization bremsstrahlung (PB) into total bremsstrahlung (BS). The present results indicate the correctness of FmodBH+PB theory in the low energy region, where the contributions of PB into BS are dominant, which is described in terms of stripped atom (SA) approximation. But at the middle and higher energy region of the bremsstrahlung spectrum, where the contribution of PB is negligible, the FmodBH theory is more close to the experimental results. Hence, it is clear that the production of PB in the low energy region, due to the dynamic response of the target atom suppresses the production of bremsstrahlung at higher energy ends.

  15. MAGNET

    CERN Multimedia

    Benoit Curé

    The cooling down to the nominal temperature of 4.5 K was achieved at the beginning of August, in conjunction with the completion of the installation work of the connection between the power lines and the coil current leads. The temperature gradient on the first exchanger of the cold box is now kept within the nominal range. A leak of lubricant on a gasket of the helium compressor station installed at the surface was observed and several corrective actions were necessary to bring the situation back to normal. The compressor had to be refilled with lubricant and a regeneration of the filters and adsorbers was necessary. The coil cool down was resumed successfully, and the cryogenics is running since then with all parameters being nominal. Preliminary tests of the 20kA coil power supply were done earlier at full current through the discharge lines into the dump resistors, and with the powering busbars from USC5 to UXC5 without the magnet connected. On Monday evening August 25th, at 8pm, the final commissionin...

  16. MAGNET

    CERN Multimedia

    Benoit Curé

    2013-01-01

    Maintenance work and consolidation activities on the magnet cryogenics and its power distribution are progressing according to the schedules. The manufacturing of the two new helium compressor frame units has started. The frame units support the valves, all the sensors and the compressors with their motors. This activity is subcontracted. The final installation and the commissioning at CERN are scheduled for March–April 2014. The overhauls of existing cryogenics equipment (compressors, motors) are in progress. The reassembly of the components shall start in early 2014. The helium drier, to be installed on the high-pressure helium piping, has been ordered and will be delivered in the first trimester of 2014. The power distribution for the helium compressors in SH5 on the 3.3kV network is progressing. The 3.3kV switches, between each compressor and its hot spare compressor, are being installed, together with the power cables for the new compressors. The 3.3kV electrical switchboards in SE5 will ...

  17. MAGNET

    CERN Multimedia

    B. Curé

    The first phase of the commissioning ended in August by a triggered fast dump at 3T. All parameters were nominal, and the temperature recovery down to 4.5K was carried out in two days by the cryogenics. In September, series of ramps were achieved up to 3 and finally 3.8T, while checking thoroughly the detectors in the forward region, measuring any movement of and around the HF. After the incident of the LHC accelerator on September 19th, corrective actions could be undertaken in the forward region. When all these displacements were fully characterized and repetitive, with no sign of increments in displacement at each field ramp, it was possible to start the CRAFT, Cosmic Run at Four Tesla (which was in fact at 3.8T). The magnet was ramped up to 18.16kA and the 3 week run went smoothly, with only 4 interruptions: due to the VIP visits on 21st October during the LHC inauguration day; a water leak on the cooling demineralized water circuit, about 1 l/min, that triggered a stop of the cooling pumps, and resulte...

  18. Applying the new gamma ray imager diagnostic to measurements of runaway electron Bremsstrahlung radiation in the DIII-D Tokamak (invited)

    Science.gov (United States)

    Cooper, C. M.; Pace, D. C.; Paz-Soldan, C.; Commaux, N.; Eidietis, N. W.; Hollmann, E. M.; Shiraki, D.

    2016-11-01

    A new gamma ray imager (GRI) is developed to probe the electron distribution function with 2D spatial resolution during runaway electron (RE) experiments at the DIII-D tokamak. The diagnostic is sensitive to 0.5-100 MeV gamma rays, allowing characterization of the RE distribution function evolution during RE growth and dissipation. The GRI consists of a lead "pinhole camera" mounted on the DIII-D midplane with 123 honeycombed tangential chords 20 cm wide that span the vessel interior. Up to 30 bismuth germanate (BGO) scintillation detectors capture RE bremsstrahlung radiation for Pulse Height Analysis (PHA) capable of discriminating up to 20 000 pulses per second. Digital signal processing routines combining shaping filters are performed during PHA to reject noise and record gamma ray energy. The GRI setup and PHA algorithms will be described and initial data from experiments will be presented. A synthetic diagnostic is developed to generate the gamma ray spectrum of a GRI channel given the plasma information and a prescribed distribution function. Magnetic reconstructions of the plasma are used to calculate the angle between every GRI sightline and orient and discriminate gamma rays emitted by a field-aligned RE distribution function.

  19. A Numerical Study of On-Axis Dose Rate from Ta and W Bremsstrahlung Converter Targets

    International Nuclear Information System (INIS)

    The bremsstrahlung converter target in radiographic accelerators is not, in general, considered a high-technology piece of equipment. In its essential form it is merely a solid plate of high-Z metal, usually tungsten (W) or tantalum (Ta); electrons go in, X-rays come out [1]. However, there are some important factors to keep in mind for this kind of target system. One is a constraint on the target itself: the proper thickness of material. Too little material reduces the probability that an electron will have a significant nuclear collision before exiting the plate. Too much material has a number of effects: small-angle scattering will occur to such an extent that bremsstrahlung photons will not be pointed in the forward direction. Electrons which small-angle scatter away and then back to the forward direction will have moved to larger radii as they traverse the target, increasing the effective source size. Electrons ''backscattered'' from the target --primaries or secondaries ejected from the upstream surface after sufficient angular scatter--exert a defocusing force on the incoming beam due to increased space charge at fixed (or even slightly reduced) current. Finally, a sufficiently thick target will begin to self-attenuate the X-ray photons produced in the upstream portion of the plate. A second constraint is obvious but is harder to accommodate when designing a radiographic accelerator system. The angular distribution of the incoming electron beam will change the forward dose. Just as electrons which have undergone small-angle scatter will no longer produce forward dose, electrons which have large angles before they ever enter the target cannot produce forward dose. Accurate prediction of dose requires incorporating the effect of the initial angle of the electron coming into the target material. The further step of controlling the angular distribution--which means keeping it as close to zero as possible--is difficult since it tends to drive important beam

  20. Thermal Bremsstrahlung probing nuclear multifragmentation in nucleus-nucleus collisions around the Fermi energy; Bremsstrahlung thermique comme sonde de la multifragmentation nucleaire dans les collisions noyau-noyau aux energies de Fermi

    Energy Technology Data Exchange (ETDEWEB)

    D' Enterria, D.G

    2000-05-15

    The thermodynamical properties of nuclear matter at moderate temperatures and densities, in the vicinity of the predicted nuclear liquid-gas phase transition, are studied using as experimental probe the hard-photons (E{sub {gamma}} > 30 MeV) emitted in nucleus-nucleus collisions. Photon and charged-particle production in four different heavy-ion reactions (Ar{sup 36} + Au{sup 197}, Ag{sup 107}, Ni{sup 58}, C{sup 12} at 60 A*MeV) is measured exclusively and inclusively coupling the TAPS photon spectrometer with two charged-particle and intermediate-mass-fragment detectors covering nearly 4{pi}. We confirm that Bremsstrahlung emission in first-chance (off-equilibrium) proton-neutron collisions (pn{gamma}) is the dominant origin of hard photons. We also firmly establish the existence of a thermal radiation component emitted in second-chance proton-neutron collisions. This thermal Bremsstrahlung emission takes place in semi-central and central nucleus-nucleus reactions involving heavy targets. We exploit this observation i) to demonstrate that thermal equilibrium is reached during the reaction, ii) to establish a new thermometer of nuclear matter based on Bremsstrahlung photons, iii) to derive the thermodynamical properties of the excited nuclear sources and, in particular, to establish a 'caloric curve' (temperature versus excitation energy), and iv) to assess the time-scales of the nuclear break-up process. (author)

  1. The luminescence of FSHA-800 type quartz - polymer optical fiber in the Bremsstrahlung gamma irradiation field

    International Nuclear Information System (INIS)

    Full text: The aim of investigations was the study of spectral and relaxation characteristics of radiation induced emission in the FSHA-800 type quartz-polymer optical fibres (OF) which are used as active media of Cherenkov's detectors in the CMS experiment (CERN). The part of OF with the length L turned in to ring of 5 cm of diameter was placed right of the way of a bunch of Bremsstrahlung gamma - rays. At the same time this OF was used for transportation of induced light which has been detected by EPP 2000C model Miniature Fiber Optic Spectrometer. The emission kinetics was measured by TDS 3032 model TEKTRONIX digital storage oscilloscope. Tungstate target plate being irradiated by electrons beam of MT-22C model microthrone (frequency of 400 Hz at a current of 7 μA) was as Bremsstrahlung gamma irradiation source (average energy of 7 MeV). For changing of irradiating dose rate the sample investigated was placed at the different distance from the target. The results of investigations The emission spectra are characterized by several bands with the maximum at 370, 420, 470, 520 and 670 nm. The transformation of the spectra take place for the different length of irradiating (L) of OF. The dose dependence of the observed emission depends on the irradiating length too. For the small value of L (0.5 m) the increasing of irradiation dose result in increasing of emission intensity. In the case of large L (5 m) we have opposite effect. The emission decay kinetics are characterized by (i) fast (time constant τ<1 μs) and slow (II) components (time constant τ- a few μs). The both spectra were measured at the irradiating dose of D=0.36 Mrad. The given curves are corrected on spectral sensitivity of the equipment. The nature of observed emission and its peculiarities are discussed in terms of existing models of radiation defect formation in the quartz glass. The influence of induced absorption on emission spectra transformation is considered. The authors express the

  2. Benchmarking of Monte Carlo simulation of bremsstrahlung from thick targets at radiotherapy energies

    Energy Technology Data Exchange (ETDEWEB)

    Faddegon, Bruce A.; Asai, Makoto; Perl, Joseph; Ross, Carl; Sempau, Josep; Tinslay, Jane; Salvat, Francesc [Department of Radiation Oncology, University of California at San Francisco, San Francisco, California 94143 (United States); Stanford Linear Accelerator Center, 2575 Sand Hill Road, Menlo Park, California 94025 (United States); National Research Council Canada, Institute for National Measurement Standards, 1200 Montreal Road, Building M-36, Ottawa, Ontario K1A 0R6 (Canada); Institut de Tecniques Energetiques, Universitat Politecnica de Catalunya and Centro de Investigacion Biomedica en Red en Bioingenieria, Biomateriales y Nanomedicina (CIBER-BBN), Diagonal 647, 08028 Barcelona (Spain); Stanford Linear Accelerator Center, 2575 Sand Hill Road, Menlo Park, California 94025 (United States); Facultat de Fisica (ECM), Universitat de Barcelona, Societat Catalana de Fisica (IEC), Diagonal 647, 08028 Barcelona (Spain)

    2008-10-15

    Several Monte Carlo systems were benchmarked against published measurements of bremsstrahlung yield from thick targets for 10-30 MV beams. The quantity measured was photon fluence at 1 m per unit energy per incident electron (spectra), and total photon fluence, integrated over energy, per incident electron (photon yield). Results were reported at 10-30 MV on the beam axis for Al and Pb targets and at 15 MV at angles out to 90 degree sign for Be, Al, and Pb targets. Beam energy was revised with improved accuracy of 0.5% using an improved energy calibration of the accelerator. Recently released versions of the Monte Carlo systems EGSNRC, GEANT4, and PENELOPE were benchmarked against the published measurements using the revised beam energies. Monte Carlo simulation was capable of calculation of photon yield in the experimental geometry to 5% out to 30 degree sign , 10% at wider angles, and photon spectra to 10% at intermediate photon energies, 15% at lower energies. Accuracy of measured photon yield from 0 to 30 degree sign was 5%, 1 s.d., increasing to 7% for the larger angles. EGSNRC and PENELOPE results were within 2 s.d. of the measured photon yield at all beam energies and angles, GEANT4 within 3 s.d. Photon yield at nonzero angles for angles covering conventional field sizes used in radiotherapy (out to 10 degree sign ), measured with an accuracy of 3%, was calculated within 1 s.d. of measurement for EGSNRC, 2 s.d. for PENELOPE and GEANT4. Calculated spectra closely matched measurement at photon energies over 5 MeV. Photon spectra near 5 MeV were underestimated by as much as 10% by all three codes. The photon spectra below 2-3 MeV for the Be and Al targets and small angles were overestimated by up to 15% when using EGSNRC and PENELOPE, 20% with GEANT4. EGSNRC results with the NIST option for the bremsstrahlung cross section were preferred over the alternative cross section available in EGSNRC and over EGS4. GEANT4 results calculated with the &apos

  3. Planar and axial coherent bremsstrahlung of type A from a 17-MeV electron beam in a diamond crystal

    International Nuclear Information System (INIS)

    Making use of the many-beam (one- and two-dimensional quantum treatment) formalism for transversely bound electrons moving through crystal lattices, we have computed planar and axial coherent bremsstrahlung (type A) spectra for 17-MeV electrons passing through a 10-μm thick diamond (C) crystal. We found that in the planar case the momentum transfer occurs in the direction perpendicular to the plane and results in a photon emission in the forward direction (electron-beam direction). In the axial case, the momentum transfer occurs in the plane perpendicular to the axis of interest. Only momentum transfers along the scan direction (electron transverse momentum direction) result in a photon emission in the forward direction. Two different scans have shown that the energies of the coherent bremsstrahlung peaks depend strongly on the direction of the electron transverse momentum but the intensities of the strongest peaks do not show any considerable change

  4. Radiation shielding considerations against gas bremsstrahlung for the BioXAS beamlines at the Canadian Light Source

    International Nuclear Information System (INIS)

    The BioXAS beamlines consist of an undulator beamline followed by two wiggler beamlines sharing the same insertion device. To contain gas bremsstrahlung in the primary optical enclosure (POE), three tungsten blocks are placed, one of which is common to all the three beamlines. A radiation shielding study is carried out for primary and secondary gas bremsstrahlung of the BioXAS beamlines. Dose rates behind the back wall, side wall and the top of the roof are obtained by calculating energy depositions in a water phantom, which surrounds the POE. Discussion is made regarding the adequacy of radiation shielding for the BioXAS beamlines, which will be built in the near future at the Canadian Light Source.

  5. The small contribution of molecular Bremsstrahlung radiation to the air-fluorescence yield of cosmic ray shower particles

    Science.gov (United States)

    Al Samarai, Imen; Deligny, Olivier; Rosado, Jaime

    2016-10-01

    A small contribution of molecular Bremsstrahlung radiation to the air-fluorescence yield in the UV range is estimated based on an approach previously developed in the framework of the radio-detection of showers in the gigahertz frequency range. First, this approach is shown to provide an estimate of the main contribution of the fluorescence yield due to the de-excitation of the C 3Πu electronic level of nitrogen molecules to the B 3Πg one amounting to Y[ 337 ] =(6.05 ± 1.50) MeV-1 at 800 hPa pressure and 293 K temperature conditions, which compares well to previous dedicated works and to experimental results. Then, under the same pressure and temperature conditions, the fluorescence yield induced by molecular Bremsstrahlung radiation is found to be Y[330-400]MBR = 0.10 MeV-1 in the wavelength range of interest for the air-fluorescence detectors used to detect extensive air showers induced in the atmosphere by ultra-high energy cosmic rays. This means that out of ≃175 photons with wavelength between 330 and 400 nm detected by fluorescence detectors, one of them has been produced by molecular Bremsstrahlung radiation. Although small, this contribution is not negligible in regards to the total budget of systematic uncertainties when considering the absolute energy scale of fluorescence detectors.

  6. Hydramite II screening tests of potential bremsstrahlung converter debris shield materials

    International Nuclear Information System (INIS)

    Results of a brief test series aimed at screening a number of potential bremsstrahlung converter debris shield materials are reported. These tests were run on Sandia National Laboratories' Hydramite II accelerator using a diode configuration which produces a pinched electron beam. The materials tested include: (1) laminated Kevlar 49/polyester and E-glass/polyester composites, (2) a low density laminated Kevlar 49 composite, and (3) two types of through-the-thickness reinforced Kevlar 49 composites. As expected, tests using laminated Kevlar 49/polyester shields showed that shield permanent set (i.e., permanent deflection) increased with increasing tantalum conversion foil thickness and decreased with increasing shield thickness. The through-the-thickness reinforced composites developed localized, but severe, back surface damage. The laminated composites displayed little back surface damage, although extensive internal matrix cracking and ply delaminations were generated. Roughly the same degree of permanent set was produced in shields made from the low density Kevlar 49 composite and the Kevlar 49/polyester. The E-glass reinforced shields exhibited relatively low levels of permanent set

  7. Search for 17-keV neutrinos in the internal bremsstrahlung spectrum of 125I

    International Nuclear Information System (INIS)

    We have conducted an experiment to search for the signature of a 17-keV neutrino in the internal bremsstrahlung (IB) spectrum of 125I. Gamma rays from a ∼ 100 mCi 125I point source were counted in a planar HPGe detector which is 16 mm in diameter and 10 mm in depth and which has a resolution of 560 eV at 122 keV. The source was counted for 61 d and the background for 17 d. At the start of the counting period the count rate was 650 s-1; the number of counts 17 keV below the 2p endpoint is 106 per keV. Data in the energy interval 120-150.5 keV were fitted with a theoretical spectrum calculated using nonrelativistic Hartree-Fock atomic wavefunctions. The preliminary fits reject the hypothesis of a 0.8% 17-keV neutrino at a confidence level of ≥ 98%. We are in the process of reanalyzing the data using recent relativistic theoretical shapes

  8. Hidden Photon Compton and Bremsstrahlung in White Dwarf Anomalous Cooling and Luminosity Functions

    CERN Document Server

    Chang, Chia-Feng

    2016-01-01

    We computed the contribution of the Compton and Bremsstrahlung processes with a hidden light $U(1)_D$ neutral boson $\\gamma_D$ to the white dwarf G117-B15A anomalous cooling rate, as well as the white dwarf luminosity functions (WDLF). We demonstrated that for a light mass of hidden photon ($m_{\\gamma_D} \\ll$ a few keV), compatible results are obtained for the recent Sloan Digital Sky Survey and the SuperCOSMOS Sky Survey observation, but the stringent limits would be imposed on the kinetic mixing $\\epsilon$. We performed $\\chi^2$-tests to acquire a quantitative assessment on the WDLF data in the context of our model, computed under the assumption of different kinetic mixing $\\epsilon$, the age of the oldest computed stars $T_D$, and a constant star formation rate $\\psi$. Then taken together, the WDLF analysis of 2$\\sigma$ confidence interval $\\epsilon = \\left( 0.37^{+0.35}_{-0.37}\\right) \\times 10^{-14}$ is barely consistent with the cooling rate analysis at 2$\\sigma$ regime $\\epsilon = \\left( 0.97^{+0.35}_{...

  9. Study of the inner Bremsstrahlung following the electron-capture decay of {sup 193} Pt

    Energy Technology Data Exchange (ETDEWEB)

    Chavez, J.Y.Z.; Cruz, M.T.F. da; Martins, M.N.; Santos, R.T. dos [Sao Paulo Univ., SP (Brazil). Inst. de Fisica; Zamboni, C.B.; Hamada, M.M.; Camargo, S.P. de; Medeiros, J.A.G. [Instituto de Pesquisas Energeticas e Nucleares (IPEN), Sao Paulo, SP (Brazil); Hindi, M.M. [Tennessee Technological Univ., Cookeville, TN (United States). Dept. of Physics

    1997-12-31

    We are measuring the inner Bremsstrahlung (I B) photons emitted in some of the electron-capture decays of {sup 193} Pt. The source was prepared with highly pure metal Pt. It was irradiated with neutron for 52 days and let to cool down for eight months. The remaining activities were due to {sup 193} Pt{sup g} (half-life 50 yr) and {sup 192} Ir (half-life 74 d), the latter coming from (n, {gamma}) reactions on a small content of Ir. We have used a radiochemistry method to reduce the Ir content of the source. The resulting Pt compound will be dissolved in a plastic scintillator disk. Most of the {sup 192} Ir decays are {beta}{sup -} and their signal in the plastic will be used as a veto for the I B-photon detector. We have performed simulations of the efficiency and absorption effects in the detection geometry. (author) 6 refs., 1 fig.; juan at if.usp.br; czamboni at net.ipen.br; hindi at hindi.physics.tntech.edu

  10. Virtual- and bremsstrahlung corrections to b -> d l+ l- in the standard model

    CERN Document Server

    Asatrian, H M; Greub, C; Walker, M

    2003-01-01

    We present the calculation of the virtual- and bremsstrahlung corrections of O(alpha_s) to the matrix elements . This is the missing piece in the NNLL results for various observables associated with the process B-> X_d l+ l-, like the branching ratio, the CP-rate asymmetry and the forward-backward asymmetry. This paper is an extension of analogous calculations done by some of us for the process B-> X_s l+ l-. As the contributions of the diagrams induced by the operators O_1^u and O_2^u with a u-quark running in the quark loop are strongly CKM suppressed, they were omitted in the analysis of B->X_s l+ l-. This is no longer possible for B-> X_d l+ l-, as the corresponding contributions are not suppressed. The main new work therefore consists of calculating the O(alpha_s) corrections to . In this paper we restrict ourselves to the range 0.05 X_d l+ l- as expansions in the small parameters s/m_b^2, z = m_c^2/m_b^2 and s/(4 m_c^2). In the phenomenological analysis at the end of the paper we discuss the impact of ...

  11. A proposed experiment to test the hydrodynamic interpretation of quantum mechanics using bremsstrahlung

    CERN Document Server

    Davidson, M P

    2003-01-01

    The mathematical expression for the electromagnetic current of a quantum particle describes an extended charge in the sense that it is non-vanishing over the volume of the wave packet or the Schroedinger wave for the particle. In the hydrodynamic model this charge current and associated density are interpreted as a physical reality. Coupling such a current to a classical electromagnetic field in the soft photon limit then results in a theory for radiation. It is shown that this predicts that bremsstrahlung is sometimes greatly suppressed when the force acting on the particle is due to a classical potential field and when the volume over which the force is active is small compared to the volume of the particle's wave packet. Solving the same problem using conventional quantum radiation theory gives a different result. Therefore it is possible to test this effect experimentally and either confirm or rule out a hydrodynamic model for Schroedinger wave mechanics. An experiment is proposed to make such a test. It ...

  12. X-rays from Proton Bremsstrahlung: Evidence from Fusion Reactors and Its Implication in Astrophysics

    CERN Document Server

    Luo, Nie

    2009-01-01

    In a fusion reactor, a proton and a neutron generated in previous reactions may again fuse with each other. Or they can in turn fuse with or be captured by an un-reacted deuteron. The average center-of-mass (COM) energy for such reaction is around 10 keV in a typical fusion reactor, but could be as low as 1 keV. At this low COM energy, the reacting nucleons are in an s-wave state in terms of their relative angular momentum. The single-gamma radiation process is thus strongly suppressed due to conservation laws. Instead the gamma ray released is likely to be accompanied by x-ray photons from a nuclear bremsstrahlung process. The x-ray thus generated has a continuous spectrum and peaks around a few hundred eV to a few keV. The average photon energy and spectrum properties of such a process are calculated with a semiclassical approach. The results give a peak near 1.1 keV for the proton-deuteron fusion and a power-to-the-minus-second law in the spectrum's high-energy limit. An analysis of some prior tokamak disc...

  13. Coherent bremsstrahlung and a new possibility to monitor collisions of beams at colliders

    Energy Technology Data Exchange (ETDEWEB)

    Kotkin, G.L. [Novosibirskij Gosudarstvennyj Univ. (Russian Federation); Serbo, V.G. [Novosibirskij Gosudarstvennyj Univ. (Russian Federation)

    1996-09-21

    We consider the coherent bremsstrahlung (CBS) at colliders with short bunches. CBS is radiation of particles of one bunch in the collective electromagnetic field of the oncoming bunch. It seems that CBS can be a potential tool for fast control over collisions and for measuring beam parameters. The bunch length {sigma}{sub z} can be found from the critical energy of the CBS spectrum E{sub c}{proportional_to}1/{sigma}{sub z}; the transverse bunch size {sigma} {sub perpendicular} {sub to} is related to the photon rate dN{sub {gamma}}{proportional_to}1/{sigma} {sub perpendicular} {sub to} {sup 2}. A specific dependence of dN{sub {gamma}} on the impact parameter between the beams allows for a fast control over the beam displacement. We present the main characteristics of CBS calculated for B and {phi} factories, LHC (in the p-p and Pb-Pb modes), RHIC, VEPP-2M and VEPP-4M. (orig.).

  14. A consistent meson-field-theoretical description of pp-bremsstrahlung

    CERN Document Server

    Eden, J A

    1996-01-01

    A parameter-free and relativistic extension of the RuhrPot meson-baryon model is used to define the dominant isoscalar meson-exchange currents. We compute pp-bremsstrahlung observables below the \\pi-production threshold using a relativistic hadronic current density that includes impulse, wave function re-orthonormalization, meson-recoil, \\bar{{\\rm N}}N creation and annihilation, \\rho\\pi\\gamma + \\omega\\pi\\gamma + \\rho\\eta\\gamma + \\omega\\eta\\gamma vector-meson decay and N\\Delta\\gamma(\\pi,\\rho) exchange currents. We obtain a good description of the available data. The N\\Delta\\gamma(\\pi) current is shown to dominate the large two-body contributions and closed-form expressions for various non-relativistic approximations are analyzed. An experimental sensitivity to the admixture of pseudo-scalar and pseudo-vector admixture of the NN\\pi interaction is demonstrated. We examine the Lorentz invariance of the NN\\rightleftharpoonsNN t-matrices and show a dominantly pseudo-vector NN\\pi coupling renders impulse approximati...

  15. Isentropic focusing of supersonic plasma jets for magnetized target fusion

    International Nuclear Information System (INIS)

    It is shown that high energy flux densities can be reached by the isentropic Prandtl-Meyer compression flow of a supersonic plasma jet in a convergent nozzle. The energy flux density thereby increases in proportion to M2/(γ-1) where M is the Mach number of the jet and γ the specific heat ratio. With an axial magnetic field set up inside the nozzle by the thermomagnetic Nernst effect, the jet is magnetically insulated from the nozzle wall, reducing the bremsstrahlung radiation and conveniently magnetizing the target plasma. A sufficiently large number of spherically arranged nozzles can then be used for the ignition and confinement of a magnetized thermonuclear target

  16. Spatially resolved hard X-ray polarization in solar flares: effects of Compton scattering and bremsstrahlung

    Science.gov (United States)

    Jeffrey, N. L. S.; Kontar, E. P.

    2011-12-01

    Aims: We study the polarization of hard X-ray (HXR) sources in the solar atmosphere, including Compton backscattering of photons in the photosphere (the albedo effect) and the spatial distribution of polarization across the source. Methods: HXR photon polarization and spectra produced via electron-ion bremsstrahlung emission are calculated from various electron distributions typical for solar flares. Compton scattering and photoelectric absorption are then modelled using Monte Carlo simulations of photon transport in the photosphere to study the observed (primary and albedo) sources. Polarization maps across HXR sources (primary and albedo components) for each of the modelled electron distributions are calculated at various source locations from the solar centre to the limb. Results: We show that Compton scattering produces a distinct polarization variation across the albedo patch at peak albedo energies of 20-50 keV for all anisotropies modelled. The results show that there are distinct spatial polarization changes in both the radial and perpendicular to radial directions across the extent of the HXR source at a given disk location. In the radial direction, the polarization magnitude and direction at specific positions along the HXR source will either increase or decrease with increased photon distribution directivity towards the photosphere. We also show how high electron cutoff energies influence the direction of polarization at above ~100 keV. Conclusions: Spatially resolved HXR polarization measurements can provide important information about the directivity and energetics of the electron distribution. Our results indicate the preferred angular resolution of polarization measurements required to distinguish between the scattered and primary components. We also show how spatially resolved polarization measurements could be used to probe the emission pattern of an HXR source, using both the magnitude and the direction of the polarization.

  17. Electron acceleration by cascading reconnection in the solar corona I Magnetic gradient and curvature effects

    CERN Document Server

    Zhou, X; Barta, M; Gan, W; Liu, S

    2015-01-01

    Aims: We investigate the electron acceleration in convective electric fields of cascading magnetic reconnection in a flaring solar corona and show the resulting hard X-ray (HXR) radiation spectra caused by Bremsstrahlung for the coronal source. Methods: We perform test particle calculation of electron motions in the framework of a guiding center approximation. The electromagnetic fields and their derivatives along electron trajectories are obtained by linearly interpolating the results of high-resolution adaptive mesh refinement (AMR) MHD simulations of cascading magnetic reconnection. Hard X-ray (HXR) spectra are calculated using an optically thin Bremsstrahlung model. Results: Magnetic gradients and curvatures in cascading reconnection current sheet accelerate electrons: trapped in magnetic islands, precipitating to the chromosphere and ejected into the interplanetary space. The final location of an electron is determined by its initial position, pitch angle and velocity. These initial conditions also influ...

  18. Neutrino Oscillation in Magnetized Gamma-Ray Burst Fireball

    OpenAIRE

    Sahu, Sarira; Fraija, Nissim; Keum, Yong-Yeon

    2009-01-01

    Neutrinos of energy about 5-20 MeV are produced due to the stellar collapse or merger events that trigger the Gamma-Ray Burst. Also low energy MeV neutrinos are produced within the fireball due to electron positron annihilation and nucleonic bremsstrahlung. Many of these neutrinos will propagate through the dense and relativistic magnetized plasma of the fireball. We have studied the possibility of resonant oscillation of $\

  19. Coronal Magnetic Fields Derived from Simultaneous Microwave and EUV Observations and Comparison with the Potential Field Model

    CERN Document Server

    Miyawaki, Shun; Shibasaki, Kiyoto; Shiota, Daikou; Nozawa, Satoshi

    2015-01-01

    We estimated the accuracy of coronal magnetic fields derived from radio observations by comparing them to potential field calculations and the DEM measurements using EUV observations. We derived line of sight component of the coronal magnetic field from polarization observations of the thermal bremsstrahlung in the NOAA active region 11150, observed around 3:00 UT on February 3, 2011 using the Nobeyama Radioheliograph at 17 GHz. Because the thermal bremsstrahlung intensity at 17 GHz includes both chromospheric and coronal components, we extracted only the coronal component by measuring the coronal emission measure in EUV observations. In addition, we derived only the radio polarization component of the corona by selecting the region of coronal loops and weak magnetic field strength in the chromosphere along the line of sight. The upper limit of the coronal longitudinal magnetic fields were determined as 100 - 210 G. We also calculated the coronal longitudinal magnetic fields from the potential field extrapola...

  20. Measuring fast electron spectra and laser absorption in relativistic laser-solid interactions using differential bremsstrahlung photon detectors

    CERN Document Server

    Scott, R H H; Perez, F; Streeter, M J V; Davies, J R; Schlenvoigt, H -P; Santos, J J; Hulin, S; Lancaster, K L; Baton, S D; Rose, S J; Norreys, P A

    2013-01-01

    A photon detector suitable for the measurement of bremsstrahlung spectra generated in relativistically-intense laser-solid interactions is described. The Monte Carlo techniques used to back-out the fast electron spectrum and laser energy absorbed into fast electrons are detailed. A relativistically-intense laser-solid experiment using frequency doubled laser light is used to demonstrate the effective operation of the detector. The experimental data was interpreted using the 3-spatial-dimension Monte Carlo code MCNPX (Pelowitz 2008), and the fast electron temperature found to be 125 keV.

  1. A search for bremsstrahlung solar axions using the Majorana low-background BEGe detector at Kimballton (MALBEK)

    CERN Document Server

    Abgrall, N; Avignone, F T; Barabash, A S; Bertrand, F E; Boswell, M; Brudanin, V; Busch, M; Caldwell, A S; Chan, Y-D; Christofferson, C D; Combs, D C; Cooper, R J; Creswick, R J; Detwiler, J A; Doe, P J; Efremenko, Yu; Egorov, V; Elliott, S R; Fast, J E; Finnerty, P; Giovanetti, G K; Goett, J; Green, M P; Gruszko, J; Guiseppe, V E; Gusev, K; Hegai, A; Henning, R; Hoppe, E W; Howard, S; Howe, M A; Keeter, K J; Kidd, M F; Knecht, A; Kochetov, O; Konovalov, S I; Kouzes, R T; LaFerriere, B D; Leon, J; Leviner, L E; Loach, J C; MacMullin, J; MacMullin, S; Marino, M G; Martin, R D; Mertens, S; Orrell, J L; O'Shaughnessy, C; Overman, N R; Phillips, D G; Poon, A W P; Pushkin, K; Radford, D C; Robertson, R G H; Ronquest, M C; Schubert, A G; Shanks, B; Shirchenko, M; Snavely, K J; Snyder, N; Steele, D; Suriano, A M; Thompson, J; Timkin, V; Varner, R L; Vasilyev, S; Vetter, K; Vorren, K; White, B R; Wilkerson, J F; Xu, W; Yakushev, E; Young, A R; Yu, C H; Yumatov, V

    2014-01-01

    A low-background, high-purity germanium detector has been used to search for evidence of low-energy, bremsstrahlung-generated solar axions. An upper bound of $1.36\\times 10^{-11}$ $(95\\% CL)$ is placed on the direct coupling of DFSZ model axions to electrons. The prospects for the sensitivity of the Majorana Demonstrator array of point-contact germanium detectors to solar axions are discussed in the context of the model-independent annual modulation due to the seasonal variation of the earth-sun distance.

  2. Inverse Bremsstrahlung Stabilization of Noise in the Generation of Ultra-short Intense Pulses by Backward Raman Amplification

    International Nuclear Information System (INIS)

    Inverse bremsstrahlung absorption of the pump laser beam in a backward Raman amplifier over the round-trip light transit time through the sub-critical density plasma can more than double the electron temperature of the plasma and produce time-varying axial temperature gradients. The resulting increased Landau damping of the plasma wave and detuning of the resonance can act to stabilize the pump against unwanted amplification of Langmuir noise without disrupting nonlinear amplification of the femtosecond seed pulse. Because the heating rate increases with the charge state Z, only low-Z plasmas (hydrogen, helium, or helium-hydrogen mixtures) will maintain a low enough temperature for efficient operation

  3. Monte-Carlo method simulation of the Bremsstrahlung mirror reflection experiment

    International Nuclear Information System (INIS)

    Full text: To detect gamma-ray mirror reflection on macroscopic smooth surface a search experiment at microtron MT-22S with 330 meter flying distance is in progress. Measured slip angles (i.e. angles between incident ray and reflector surface) don't exceed tens of micro-radian. Under such angles an effect of the reflection could be easily veiled due to negative background conditions. That is why the process needed to be simulated by Monte-Carlo method as accurate as possible and corresponding computer program was developed. A first operating mode of the MT-22S generates 13 MeV electrons that are incident on a Bremsstrahlung target. So energies of gamma-rays were simulated to be in the range of 0.01†12.5 MeV and be distributed by known Shift formula. When any gamma-quantum was incident on the reflector it resulted in following two cases. If its slip angle was more than the critical one, gamma-quantum was to be absorbed by the reflector and the program started to simulate next event. In the other case the program replaced incident gamma-quantum trajectory parameters by the reflected ones. The gamma-quantum trajectory behind the reflector was traced till its detector. Any gamma-quantum that got the detector was to be registered. As any simulated gamma-quantum was of random energy the critical slip angle of every simulated event was evaluated by the following formula: αcrit = eh/E √ZNAρ/πAm. Table values of the absorption coefficients were used for random simulation of gamma-quanta absorption in the air. And it was assumed that any gamma-quantum interaction with air resulted in its disappearance. Dependence of different flying distances (120 and 330 m), gap heights (10, 20 and 50 μ) of the gap collimator and inclinations (20 and 40 μrad) of the reflector's plane on detected gamma-quanta energy distribution and vertical angle one was studied with a help of the developed program

  4. Test of Compton camera components for prompt gamma imaging at the ELBE bremsstrahlung beam

    Science.gov (United States)

    Hueso-González, F.; Golnik, C.; Berthel, M.; Dreyer, A.; Enghardt, W.; Fiedler, F.; Heidel, K.; Kormoll, T.; Rohling, H.; Schöne, S.; Schwengner, R.; Wagner, A.; Pausch, G.

    2014-05-01

    In the context of ion beam therapy, particle range verification is a major challenge for the quality assurance of the treatment. One approach is the measurement of the prompt gamma rays resulting from the tissue irradiation. A Compton camera based on several position sensitive gamma ray detectors, together with an imaging algorithm, is expected to reconstruct the prompt gamma ray emission density map, which is correlated with the dose distribution. At OncoRay and Helmholtz-Zentrum Dresden-Rossendorf (HZDR), a Compton camera setup is being developed consisting of two scatter planes: two CdZnTe (CZT) cross strip detectors, and an absorber consisting of one Lu2SiO5 (LSO) block detector. The data acquisition is based on VME electronics and handled by software developed on the ROOT framework. The setup has been tested at the linear electron accelerator ELBE at HZDR, which is used in this experiment to produce bunched bremsstrahlung photons with up to 12.5 MeV energy and a repetition rate of 13 MHz. Their spectrum has similarities with the shape expected from prompt gamma rays in the clinical environment, and the flux is also bunched with the accelerator frequency. The charge sharing effect of the CZT detector is studied qualitatively for different energy ranges. The LSO detector pixel discrimination resolution is analyzed and it shows a trend to improve for high energy depositions. The time correlation between the pulsed prompt photons and the measured detector signals, to be used for background suppression, exhibits a time resolution of 3 ns FWHM for the CZT detector and of 2 ns for the LSO detector. A time walk correction and pixel-wise calibration is applied for the LSO detector, whose resolution improves up to 630 ps. In conclusion, the detector setup is suitable for time-resolved background suppression in pulsed clinical particle accelerators. Ongoing tasks are the quantitative comparison with simulations and the test of imaging algorithms. Experiments at proton

  5. Dose calculations using MARS for Bremsstrahlung beam stops and collimators in APS beamline stations.

    Energy Technology Data Exchange (ETDEWEB)

    Dooling, J.; Accelerator Systems Division (APS)

    2010-11-01

    The Monte Carlo radiation transport code MARS is used to model the generation of gas bremsstrahlung (GB) radiation from 7-GeV electrons which scatter from residual gas atoms in undulator straight sections within the Advanced Photon Source (APS) storage ring. Additionally, MARS is employed to model the interactions of the GB radiation with components along the x-ray beamlines and then determine the expected radiation dose-rates that result. In this manner, MARS can be used to assess the adequacy of existing shielding or the specifications for new shielding when required. The GB radiation generated in the 'thin-target' of an ID straight section will consist only of photons in a 1/E-distribution up to the full energy of the stored electron beam. Using this analytical model, the predicted GB power for a typical APS 15.38-m insertion device (ID) straight section is 4.59 x 10{sup -7} W/nTorr/mA, assuming a background gas composed of air (Z{sub eff} = 7.31) at room temperature (293K). The total GB power provides a useful benchmark for comparisons between analytical and numerical approaches. We find good agreement between MARS and analytical estimates for total GB power. The extended straight section 'target' creates a radial profile of GB, which is highly peaked centered on the electron beam. The GB distribution reflects the size of the electron beam that creates the radiation. Optimizing the performance of MARS in terms of CPU time per incident trajectory requires the use of a relatively short, high-density gas target (air); in this report, the target density is {rho}L = 2.89 x 10{sup -2} g/cm{sup 2} over a length of 24 cm. MARS results are compared with the contact dose levels reported in TB-20, which used EGS4 for radiation transport simulations. Maximum dose-rates in 1 cc of tissue phantom form the initial basis for comparison. MARS and EGS4 results are approximately the same for maximum 1-cc dose-rates and attenuation in the photon

  6. Modeling a one-dimensional bremsstrahlung and neutron imaging array for use on Sandia close-quote s Z machine

    International Nuclear Information System (INIS)

    Inertial confinement fusion is being studied on the Z facility at Sandia National Laboratories. Z is a large z-pinch machine which can provide 20 MA of current to z-pinch loads producing ∼1.8 MJ of soft x rays in less than 10 ns. Within the pinch region, decelerated electrons produce a strong source of bremsstrahlung radiation which varies from shot to shot. Additionally, a variety of inertial confinement fusion targets may produce fusion neutrons, the intensity and distribution of which depend on the temperature and density of the pinch. In this article, we describe the computer modeling behind the shielding design of a simple time-resolved, one-dimensional imaging array. This diagnostic will provide a time history for both the bremsstrahlung and neutron production as a function of height in the target. Calculations show that by building an array of scintillator fibers separated by long, thin tungsten collimator plates, a sampling rate of 0.254 mm at the target can be achieved. The corresponding channel-to-channel discrimination for such a design is shown to be better than 1000 ampersand as;1 for <4 MeV photons and 100 ampersand as;1 for 2.45 MeV neutrons. By coupling scintillator fibers to a fiber-optic streak camera system, the system time response is expected to be dominated by the scintillator response (∼1.2 ns). copyright 1999 American Institute of Physics

  7. Attenuation of bremsstrahlung from 90Sr-90Y, 147Pm and 204Tl in thick target compounds

    Science.gov (United States)

    Manjunatha, H. C.

    2014-11-01

    The external bremsstrahlung (EB) produced by beta particles such as from 90Sr-90Y, 147Pm and 204Tl in PbCl2, PbF2, Pb(NO3)2 and CdO were measured using NaI(Tl) crystal. The beta stopper technique is employed to measure the integral intensities above 100 keV energy in different absorber thicknesses. Attenuation of the external bremsstrahlung, excited by 90Sr-90Y, 147Pm and 204Tl beta-emitters in the same compounds has also been studied. The measured attenuation parameter is not constant with absorber thickness and it increases with increasing Zmod of the absorber. Whereas, the mass attenuation coefficient of gamma rays of equivalent energy is independent of the absorber thickness. This confirms that the attenuation of EB in an absorber does not conform to a single exponential law, unlike the absorption of monoenergetic gamma rays. Rather it may be a combination of a large number of exponential terms.

  8. Energy spectra of secondary neutrons produced by high-energy bremsstrahlung in carbon, nitrogen, oxygen and tissue

    International Nuclear Information System (INIS)

    The energy spectra of secondary neutrons produced when bremsstrahlung of end-point energy in the range 10-30 MeV is incident on oxygen, carbon and nitrogen have been calculated. Photonuclear reactions of the type (γ,n) and (γ,pn) have been included. The respective contributions of various nuclear reactions have been adjusted using the published values of experimentally determined cross-sections, or branching ratios, where these are available. Where no such information exists in the literature, the values have been empirically estimated. Agreement has been obtained between the calculated photoneutron spectra from C, N and O at various energies and the available experimentally-measured spectra. The photoneutron spectra from C,N and O have been combined in the right proportion (C5H40O18N) to compute the spectra of secondary neutrons from tissue irradiated with bremsstrahlung of end-point energy from 10-30 MeV. Mean neutron energies and kerma factors for these spectra have been calculated. (author)

  9. Angular distribution of Bremsstrahlung photons and of positrons for calculations of terrestrial gamma-ray flashes and positron beams

    CERN Document Server

    Koehn, Christoph

    2012-01-01

    Within thunderstorms electrons can gain energies of up to hundred(s) of MeV. These electrons can create X-rays and gamma-rays as Bremsstrahlung when they collide with air molecules. Here we calculate the distribution of angles between incident electrons and emitted photons as a function of electron and photon energy. We derive these doubly differential cross-sections by integrating analytically over the triply differential cross-sections derived by Bethe and Heitler; this is appropriate for light atoms like nitrogen and oxygen and for electron energies between 1 keV and 1 GeV. We also discuss some simplifying limit cases, and we derive some simple approximation for the most probable scattering angle. We also provide cross sections for the production of electron positron pairs from energetic photons when they interact with air molecules. This process is related to the Bremsstrahlung process by some physical symmetry. Therefore the results above can be transferred to predictions on the angles between incident p...

  10. The Small Contribution of Molecular Bremsstrahlung Radiation to the Air-Fluorescence Yield of Cosmic Ray Shower Particles

    CERN Document Server

    Samarai, I Al; Rosado, J

    2016-01-01

    A small contribution of molecular Bremsstrahlung radiation to the air-fluorescence yield in the UV range is estimated based on an approach previously developed in the framework of the radio-detection of showers in the gigahertz frequency range. First, this approach is shown to provide an estimate of the main contribution of the fluorescence yield due to the de-excitation of the C $^3\\Pi_{\\mathrm{u}}$ electronic level of nitrogen molecules to the B $^3\\Pi_{\\mathrm{g}}$ one amounting to $Y_{[337]}=(6.05\\pm 1.50)~$ MeV$^{-1}$ at 800 hPa pressure and 293 K temperature conditions, which compares well to previous dedicated works and to experimental results. Then, under the same pressure and temperature conditions, the fluorescence yield induced by molecular Bremsstrahlung radiation is found to be $Y_{[330-400]}^{\\mathrm{MBR}}=0.10~$ MeV$^{-1}$ in the wavelength range of interest for the air-fluorescence detectors used to detect extensive air showers induced in the atmosphere by ultra-high energy cosmic rays. This m...

  11. Role of medium modifications for neutrino-pair processes from nucleon-nucleon bremsstrahlung - Impact on the protoneutron star deleptonization

    CERN Document Server

    Fischer, Tobias

    2016-01-01

    In this article the neutrino-pair production from nucleon-nucleon (NN) bremsstrahlung is explored via medium-modifications of the strong interactions at the level of the one-pion exchange approximation. It governs the bulk part of the NN interaction at low densities relevant for the neutrino physics in core-collapse supernova studies. The resulting medium modified one-pion exchange rate for the neutrino-pair processes is implemented in simulations of core collapse supernovae in order to study the impact on the neutrino signal emitted from the deleptonization of the nascent proto-neutron star. Consequences for the nucleosynthesis of heavy elements of the material ejected from the PNS surface are discussed.

  12. Production of isotopes and isomers with irradiation of Z = 47–50 targets by 23-MeV bremsstrahlung

    Energy Technology Data Exchange (ETDEWEB)

    Karamian, S. A., E-mail: karamian@nrmail.jinr.ru [Joint Institute for Nuclear Research (Russian Federation); Carroll, J. J. [US Army Research Laboratory (United States); Aksenov, N. V.; Albin, Yu. A.; Belov, A. G.; Bozhikov, G. A.; Dmitriev, S. N.; Starodub, G. Ya. [Joint Institute for Nuclear Research (Russian Federation)

    2015-09-15

    The irradiations of Ag to Sn targets by bremsstrahlung generated with 23-MeV electron beams are performed at the MT-25 microtron. Gamma spectra of the induced activities have been measured and the yields of all detected radionuclides and isomers are carefully measured and analyzed. A regular dependence of yields versus changed reaction threshold is confirmed. Many isomers are detected and the suppression of the production probability is observed with growing product spin. Special peculiarities for the isomer-to-ground state ratios were deduced for the {sup 106m}Ag, {sup 108m}Ag, {sup 113m}In, {sup 115m}In, and {sup 123m}Sn isomers. The production of such nuclides as {sup 108m}Ag, {sup 115m}In, {sup 117g}In, and {sup 113m}Cd is of interest for applications, especially when economic methods are available.

  13. Higher-order corrections to electron-nucleus bremsstrahlung cross sections above a few MeV

    Science.gov (United States)

    Mangiarotti, A.; Martins, M. N.

    2016-08-01

    Despite the fact that the first calculations of nuclear bremsstrahlung cross sections were performed for relativistic electrons more than 80 years ago by Sauter, Bethe and Heitler, and Racah, a fully satisfactory solution to this problem is still missing up to the present day. Numerical approaches are impractical for electrons with energies above a few MeV because they require a prohibitively large number of partial waves. Analytic formulae need to describe simultaneously and accurately the interaction with the Coulomb field of the nucleus and the screening effect of the atomic electrons. In the present paper, a state-of-the-art analytic calculation will be discussed. In particular, higher-order corrections to the interaction with the Coulomb field of the nucleus, a subject seldom tackled in the past, are included and compared extensively with published data. The emerged difficulties will be highlighted, but unfortunately they can be overcome only with future large coordinated theoretical and experimental efforts.

  14. Channeling and coherent bremsstrahlung effects for relativistic positrons and electrons. [16 to 28 MeV, orientation

    Energy Technology Data Exchange (ETDEWEB)

    Walker, R. L.

    1976-03-22

    Channeling of positrons in single crystals of silicon was observed in transmission and scattering measurements for incident energies from 16 to 28 MeV. In addition, the spectral dependence upon crystal orientation of the forward coherent bremsstrahlung produced by beams of 28-MeV positrons and electrons incident upon a 5 ..mu..m thick single crystal of silicon was measured with a NaI photon spectrometer. Effects of channeling and perhaps of the nonvalidity of the first Born approximation were observed for beam directions near the (111) axis of the crystal, and coherent peaks near 0.5 MeV were observed for a compound interference direction, in agreement with first-order theoretical calculations. 32 fig.

  15. Study of the K shell photoelectric parameters of Dy, Yb and W atoms using low energy Bremsstrahlung radiation

    Energy Technology Data Exchange (ETDEWEB)

    Hosur, S.B.; Naika, L.R.; Badiger, N.M. [Department of Studies in PhysicsKarnatak University, Dharwad - 580003 (India)

    2011-04-15

    Low energy external Bremsstrahlung (EB) photons were used to estimate the K shell photoelectric parameters; the K shell photoelectric cross section at the K edge, the K shell binding energy, the K shell jump ratio, the K shell jump factors, the Davisson-Kirchner ratio and the K shell oscillator strength for dysprosium (Dy), ytterbium (Yb) and tungsten (W) atoms. The EB photons are produced in the nickel (Ni) target by using the beta particles from a weak beta source of {sup 90}Sr-{sup 90}Y. These photons are made to fall on these elemental targets of our interest and the transmitted spectrum is measured using GMX 10P HPGe detector coupled to an 8K multichannel analyzer. The sharp decrease at the K edge in the measured spectrum is used to determine the K shell photoelectric parameters of these elements. The experimental results are in good agreement with the theoretical values. (authors)

  16. Study of the K shell photoelectric parameters of Dy, Yb and W atoms using low energy Bremsstrahlung radiation

    International Nuclear Information System (INIS)

    Low energy external Bremsstrahlung (EB) photons were used to estimate the K shell photoelectric parameters; the K shell photoelectric cross section at the K edge, the K shell binding energy, the K shell jump ratio, the K shell jump factors, the Davisson-Kirchner ratio and the K shell oscillator strength for dysprosium (Dy), ytterbium (Yb) and tungsten (W) atoms. The EB photons are produced in the nickel (Ni) target by using the beta particles from a weak beta source of 90Sr-90Y. These photons are made to fall on these elemental targets of our interest and the transmitted spectrum is measured using GMX 10P HPGe detector coupled to an 8K multichannel analyzer. The sharp decrease at the K edge in the measured spectrum is used to determine the K shell photoelectric parameters of these elements. The experimental results are in good agreement with the theoretical values. (authors)

  17. Observation of planar three-jet events in e+e- annihilation and evidence for gluon bremsstrahlung

    International Nuclear Information System (INIS)

    Topological distributions of charged and neutral hadrons from the reaction e+e%YI multihadrons are studied at √s of about 30 GeV. An excess of planar events is observed at a rate which cannot be explained by statistical fluctuations in the two-jet process. The planar events, mostly consisting of a slim jet on one side and a broader jet on the other, are shown actually to possess three-jet structure by demonstrating that the broader jet itself consists of two collinear jets in its own rest system. Detailed agreement between data and predictions is obtained if the process e+e- → q anti q g is taken into account. This strongly suggests gluon bremsstrahlung as the origin of the planar three-jet events. The data are consistent with a strong coupling constant αs (q2) of about 0.17. (orig.) 891 HSI/orig. 892 RDG

  18. Quantitative comparison of PET and Bremsstrahlung SPECT for imaging the in vivo yttrium-90 microsphere distribution after liver radioembolization.

    Directory of Open Access Journals (Sweden)

    Mattijs Elschot

    Full Text Available BACKGROUND: After yttrium-90 ((90Y microsphere radioembolization (RE, evaluation of extrahepatic activity and liver dosimetry is typically performed on (90Y Bremsstrahlung SPECT images. Since these images demonstrate a low quantitative accuracy, (90Y PET has been suggested as an alternative. The aim of this study is to quantitatively compare SPECT and state-of-the-art PET on the ability to detect small accumulations of (90Y and on the accuracy of liver dosimetry. METHODOLOGY/PRINCIPAL FINDINGS: SPECT/CT and PET/CT phantom data were acquired using several acquisition and reconstruction protocols, including resolution recovery and Time-Of-Flight (TOF PET. Image contrast and noise were compared using a torso-shaped phantom containing six hot spheres of various sizes. The ability to detect extra- and intrahepatic accumulations of activity was tested by quantitative evaluation of the visibility and unique detectability of the phantom hot spheres. Image-based dose estimates of the phantom were compared to the true dose. For clinical illustration, the SPECT and PET-based estimated liver dose distributions of five RE patients were compared. At equal noise level, PET showed higher contrast recovery coefficients than SPECT. The highest contrast recovery coefficients were obtained with TOF PET reconstruction including resolution recovery. All six spheres were consistently visible on SPECT and PET images, but PET was able to uniquely detect smaller spheres than SPECT. TOF PET-based estimates of the dose in the phantom spheres were more accurate than SPECT-based dose estimates, with underestimations ranging from 45% (10-mm sphere to 11% (37-mm sphere for PET, and 75% to 58% for SPECT, respectively. The differences between TOF PET and SPECT dose-estimates were supported by the patient data. CONCLUSIONS/SIGNIFICANCE: In this study we quantitatively demonstrated that the image quality of state-of-the-art PET is superior over Bremsstrahlung SPECT for the

  19. Studies of total bremsstrahlung in thick targets of Al, Ti, Sn and Pb for 90Sr beta particles in the photon energy region of 1-100 keV

    Science.gov (United States)

    Singh, Amrit; Dhaliwal, A. S.

    2016-02-01

    Total bremsstrahlung (BS) spectra in thick targets of Al, Ti, Sn and Pb produced by beta emitter 90Sr (End point energy=546 keV) are studied in the photon energy range of 1-100 keV. The experimentally measured BS spectra are compared with the theoretical spectral distributions calculated from Elwert corrected (non relativistic) Bethe-Heitler [EBH] theory, modified Elwert factor (relativistic) Bethe-Heitler [Fmod BH] theory for ordinary bremsstrahlung (OB) and the Avdonina and Pratt [Fmod BH+PB] theory, which include the contribution of polarization bremsstrahlung (PB) into OB. The present results are indicating the correctness of Fmod BH+PB theory in the low energy region, where PB dominates into the BS, but at the middle and higher photon energy region of the bremsstrahlung spectrum, the Fmod BH theory is more close to the experimental results. The description of the bremsstrahlung process in stripped atom (SA) approximation, which indicates the suppression of the bremsstrahlung at higher energy ends due to the production of PB in the low energy region, needs further considerations. Hence, the present measurements for BS for different target materials indicates that the considerations of the screening effects along with other secondary effects during the interaction of incident electrons with the target nuclei are important while describing the production of bremsstrahlung, particularly for the higher energy regions.

  20. Spatial configuration of a plasma bunch formed under gyromagnetic resonance in a magnetic mirror trap

    Science.gov (United States)

    Andreev, V. V.; Novitskii, A. A.; Umnov, A. M.; Chuprov, D. V.

    2016-06-01

    The spatial configuration of a relativistic plasma bunch generated under the gyromagnetic autoresonance and confined in a magnetic mirror trap has been studied experimentally and numerically. The characteristics of bremsstrahlung generated by the plasma bunch from the gas and chamber walls were investigated using X-ray spectroscopy and radiometry, which made it possible to determine the localization of the bunch and analyze the dynamics of its confinement.

  1. Kinetic modeling of Nernst effect in magnetized hohlraums

    Science.gov (United States)

    Joglekar, A. S.; Ridgers, C. P.; Kingham, R. J.; Thomas, A. G. R.

    2016-04-01

    We present nanosecond time-scale Vlasov-Fokker-Planck-Maxwell modeling of magnetized plasma transport and dynamics in a hohlraum with an applied external magnetic field, under conditions similar to recent experiments. Self-consistent modeling of the kinetic electron momentum equation allows for a complete treatment of the heat flow equation and Ohm's law, including Nernst advection of magnetic fields. In addition to showing the prevalence of nonlocal behavior, we demonstrate that effects such as anomalous heat flow are induced by inverse bremsstrahlung heating. We show magnetic field amplification up to a factor of 3 from Nernst compression into the hohlraum wall. The magnetic field is also expelled towards the hohlraum axis due to Nernst advection faster than frozen-in flux would suggest. Nonlocality contributes to the heat flow towards the hohlraum axis and results in an augmented Nernst advection mechanism that is included self-consistently through kinetic modeling.

  2. Magnetic ripple and the modeling of lower-hybrid current drive in tokamaks

    Energy Technology Data Exchange (ETDEWEB)

    Peysson, Y.; Arslanbekov, R.; Basiuk, V.; Carrasco, J.; Litaudon, X.; Moreau, D. [Association Euratom-CEA, Centre d`Etudes de Cadarache, 13 - Saint-Paul-lez-Durance (France). Dept. de Recherches sur la Fusion Controlee; Bizarro, J.P. [Instituto Superior Tecnico, Lisbon (Portugal). Lab. de Quimica Organica

    1996-01-01

    Using ray-tracing, a detailed investigation of the lower hybrid (LH) wave propagation in presence of toroidal magnetic field ripple is presented. By coupling ray tracing with a one-dimensional relativistic Fokker-Planck code, simulations of LH experiments have been performed for the Tore Supra tokamak. Taking into account magnetic ripple in LH simulations, a better agreement is found between numerical predictions and experimental observations, such as non-thermal Bremsstrahlung emission, current profile, ripple-induced power losses in local magnetic mirrors, when plasma conditions correspond to the ` `few passes` regime. (author). 47 refs.

  3. Magnetic ripple and the modeling of lower-hybrid current drive in tokamaks

    International Nuclear Information System (INIS)

    Using ray-tracing, a detailed investigation of the lower hybrid (LH) wave propagation in presence of toroidal magnetic field ripple is presented. By coupling ray tracing with a one-dimensional relativistic Fokker-Planck code, simulations of LH experiments have been performed for the Tore Supra tokamak. Taking into account magnetic ripple in LH simulations, a better agreement is found between numerical predictions and experimental observations, such as non-thermal Bremsstrahlung emission, current profile, ripple-induced power losses in local magnetic mirrors, when plasma conditions correspond to the ' 'few passes' regime. (author)

  4. Optimization of energy window for {sup 90}Y bremsstrahlung SPECT imaging for detection tasks using the ideal observer with model-mismatch

    Energy Technology Data Exchange (ETDEWEB)

    Rong Xing; Ghaly, Michael; Frey, Eric C. [Department of Radiology, Johns Hopkins University, Baltimore, Maryland 21287-0859 (United States)

    2013-06-15

    Purpose: In yttrium-90 ({sup 90}Y) microsphere brachytherapy (radioembolization) of unresectable liver cancer, posttherapy {sup 90}Y bremsstrahlung single photon emission computed tomography (SPECT) has been used to document the distribution of microspheres in the patient and to help predict potential side effects. The energy window used during projection acquisition can have a significant effect on image quality. Thus, using an optimal energy window is desirable. However, there has been great variability in the choice of energy window due to the continuous and broad energy distribution of {sup 90}Y bremsstrahlung photons. The area under the receiver operating characteristic curve (AUC) for the ideal observer (IO) is a widely used figure of merit (FOM) for optimizing the imaging system for detection tasks. The IO implicitly assumes a perfect model of the image formation process. However, for {sup 90}Y bremsstrahlung SPECT there can be substantial model-mismatch (i.e., difference between the actual image formation process and the model of it assumed in reconstruction), and the amount of the model-mismatch depends on the energy window. It is thus important to account for the degradation of the observer performance due to model-mismatch in the optimization of the energy window. The purpose of this paper is to optimize the energy window for {sup 90}Y bremsstrahlung SPECT for a detection task while taking into account the effects of the model-mismatch. Methods: An observer, termed the ideal observer with model-mismatch (IO-MM), has been proposed previously to account for the effects of the model-mismatch on IO performance. In this work, the AUC for the IO-MM was used as the FOM for the optimization. To provide a clinically realistic object model and imaging simulation, the authors used a background-known-statistically and signal-known-statistically task. The background was modeled as multiple compartments in the liver with activity parameters independently following a

  5. Optimization of energy window for 90Y bremsstrahlung SPECT imaging for detection tasks using the ideal observer with model-mismatch

    International Nuclear Information System (INIS)

    Purpose: In yttrium-90 (90Y) microsphere brachytherapy (radioembolization) of unresectable liver cancer, posttherapy 90Y bremsstrahlung single photon emission computed tomography (SPECT) has been used to document the distribution of microspheres in the patient and to help predict potential side effects. The energy window used during projection acquisition can have a significant effect on image quality. Thus, using an optimal energy window is desirable. However, there has been great variability in the choice of energy window due to the continuous and broad energy distribution of 90Y bremsstrahlung photons. The area under the receiver operating characteristic curve (AUC) for the ideal observer (IO) is a widely used figure of merit (FOM) for optimizing the imaging system for detection tasks. The IO implicitly assumes a perfect model of the image formation process. However, for 90Y bremsstrahlung SPECT there can be substantial model-mismatch (i.e., difference between the actual image formation process and the model of it assumed in reconstruction), and the amount of the model-mismatch depends on the energy window. It is thus important to account for the degradation of the observer performance due to model-mismatch in the optimization of the energy window. The purpose of this paper is to optimize the energy window for 90Y bremsstrahlung SPECT for a detection task while taking into account the effects of the model-mismatch. Methods: An observer, termed the ideal observer with model-mismatch (IO-MM), has been proposed previously to account for the effects of the model-mismatch on IO performance. In this work, the AUC for the IO-MM was used as the FOM for the optimization. To provide a clinically realistic object model and imaging simulation, the authors used a background-known-statistically and signal-known-statistically task. The background was modeled as multiple compartments in the liver with activity parameters independently following a Gaussian distribution; the

  6. Reconstruction of the Bremsstrahlung spectrum a medical linear accelerator from the gradient of the depth dose curve in a water container; Reconstruccion del espectro Bremsstrahlung emitido por un acelerador lineal medico a partir del gradiente de las curvas de dosisen profundidad en una cuba de agua

    Energy Technology Data Exchange (ETDEWEB)

    Juste, B.; Miro, R.; Verdu, G.; Diez, S.; Campayo, J. M.

    2010-07-01

    Determining the spectral distribution of the emitted photon medical linear accelerator (linac) used in radiotherapy treatment is extremely important for performing dosimetry calculations as to accurately calculate the therapeutic dose distributions. Since directly measure the spectrum is very complicated, this paper presents an indirect technique to accurately calculate the spectra of Bremsstrahlung photons emitted by linacs.

  7. Photoactivation of the p-nucleus {sup 92}Mo at the bremsstrahlung measurement place of ELBE; Photoaktivierung des p-Kerns {sup 92}Mo am Bremsstrahlungsmessplatz von ELBE

    Energy Technology Data Exchange (ETDEWEB)

    Erhard, Martin Andreas

    2010-02-26

    By the high intensity of the bremsstrahlung of up to 20 MeV to 10{sup 9} MeV{sup -1}cm{sup -2}s{sup -1} in the energy range up to 20 MeV in the framework of this thesis for the first time not only the ({gamma},n), but also the ({gamma},p) reactions could be studied on {sup 92}Mo at astrophysically relevant energies.

  8. A bremsstrahlung gamma-ray source based on stable ionization injection of electrons into a laser wakefield accelerator

    CERN Document Server

    Döpp, A; Thaury, C; Lifschitz, A; Sylla, F; Goddet, J-P; Tafzi, A; Iaquanello, G; Lefrou, T; Rousseau, P; Conejero, E; Ruiz, C; Phuoc, K Ta; Malka, V

    2016-01-01

    Laser wakefield acceleration permits the generation of ultra-short, high-brightness relativistic electron beams on a millimeter scale. While those features are of interest for many applications, the source remains constraint by the poor stability of the electron injection process. Here we present results on injection and acceleration of electrons in pure nitrogen and argon. We observe stable, continuous ionization-induced injection of electrons into the wakefield for laser powers exceeding a threshold of 7 TW. The beam charge scales approximately linear with the laser energy and is limited by beam loading. For 40 TW laser pulses we measure a maximum charge of almost 1 nC per shot, originating mostly from electrons of less than 10 MeV energy. The relatively low energy, the high charge and its stability make this source well-suited for applications such as non-destructive testing. Hence, we demonstrate the production of energetic radiation via bremsstrahlung conversion at 1 Hz repetition rate. In accordance wit...

  9. A bremsstrahlung gamma-ray source based on stable ionization injection of electrons into a laser wakefield accelerator

    Science.gov (United States)

    Döpp, A.; Guillaume, E.; Thaury, C.; Lifschitz, A.; Sylla, F.; Goddet, J.-P.; Tafzi, A.; Iaquanello, G.; Lefrou, T.; Rousseau, P.; Conejero, E.; Ruiz, C.; Ta Phuoc, K.; Malka, V.

    2016-09-01

    Laser wakefield acceleration permits the generation of ultra-short, high-brightness relativistic electron beams on a millimeter scale. While those features are of interest for many applications, the source remains constraint by the poor stability of the electron injection process. Here we present results on injection and acceleration of electrons in pure nitrogen and argon. We observe stable, continuous ionization-induced injection of electrons into the wakefield for laser powers exceeding a threshold of 7 TW. The beam charge scales approximately with the laser energy and is limited by beam loading. For 40 TW laser pulses we measure a maximum charge of almost 1 nC per shot, originating mostly from electrons of less than 10 MeV energy. The relatively low energy, the high charge and its stability make this source well-suited for applications such as non-destructive testing. Hence, we demonstrate the production of energetic radiation via bremsstrahlung conversion at 1 Hz repetition rate. In accordance with GEANT4 Monte-Carlo simulations, we measure a γ-ray source size of less than 100 μm for a 0.5 mm tantalum converter placed at 2 mm from the accelerator exit. Furthermore we present radiographs of image quality indicators.

  10. Optical time of flight studies of lithium plasma in double pulse laser ablation: Evidence of inverse Bremsstrahlung absorption

    Energy Technology Data Exchange (ETDEWEB)

    Sivakumaran, V.; Joshi, H. C.; Singh, R. K.; Kumar, Ajai, E-mail: ajai@ipr.res.in [Institute for Plasma Research, Bhat, Gandhinagar, Gujarat 382428 (India)

    2014-06-15

    The early stage of formation of lithium plasma in a collinear—double pulse laser ablation mode has been studied using optical time of flight (OTOF) spectroscopy as a function of inter-pulse delay time, the distance from the target surface and the fluence of the ablation lasers. The experimental TOF measurements were carried out for lithium neutral (670.8 nm and 610.3 nm), and ionic (548.4 nm and 478.8 nm) lines. These experimental observations have been compared with that for single pulse laser ablation mode. It is found that depending on the fluence and laser pulse shape of the first pre-ablation laser and the second main ablation laser, the plasma plume formation and its characteristic features can be described in terms of plume-plume or laser-plume interaction processes. Moreover, the enhancement in the intensity of Li neutral and ionic lines is observed when the laser-plume interaction is the dominant process. Here, we see the evidence of the role of inverse Bremsstrahlung absorption process in the initial stage of formation of lithium plasma in this case.

  11. Neutron-proton bremsstrahlung from intermediate energy heavy-ion reactions as a probe of the nuclear symmetry energy?

    International Nuclear Information System (INIS)

    Hard photons from neutron-proton bremsstrahlung in intermediate energy heavy-ion reactions are examined as a potential probe of the nuclear symmetry energy within a transport model. Effects of the symmetry energy on the yields and spectra of hard photons are found to be generally smaller than those due to the currently existing uncertainties of both the in-medium nucleon-nucleon cross sections and the photon production probability in the elementary process pn→pnγ. Very interestingly, nevertheless, the ratio of hard photon spectra R1/2(γ) from two reactions using isotopes of the same element is not only approximately independent of these uncertainties but also quite sensitive to the symmetry energy. For the head-on reactions of 132Sn + 124Sn and 112Sn + 112Sn at Ebeam/A=50 MeV, for example, the R1/2(γ) displays a rise up to 15% when the symmetry energy is reduced by about 20% at ρ=1.3ρ0 which is the maximum density reached in these reactions

  12. Electron elastic scattering and low-frequency bremsstrahlung on A@$C_{60}$: A model static approximation

    CERN Document Server

    Dolmatov, V K; Cooper, M B; Hunter, M E

    2015-01-01

    Electron elastic-scattering phase shifts and cross sections along with the differential and total cross sections and polarization of low-frequency bremsstrahlung upon low-energy electron collision with endohedral fullerenes $A$@C$_{60}$ are theoretically scrutinized versus the nature, size and spin of the encapsulated atom $A$. The case-study-atoms $A$ are N, Ar, Cr, Mn, Mo, Tc, Xe, Ba, and Eu. They are thoughtfully picked out of different rows of the periodic table. The study is performed in the framework of a model static approximation. There, both the encapsulated atom $A$ and C$_{60}$ cage are regarded as non-polarizable targets. The C$_{60}$ cage is modeled by an attractive spherical annular potential well. The study provides the most complete initial understanding of how the processes of interest might evolve upon electron collision with various $A$@C$_{60}$. Calculated results identify the most interesting and/or useful future measurements or more rigorous calculations of an electron+$A$@C$_{60}$ colli...

  13. Numerical investigation into the highly nonlinear heat transfer equation with bremsstrahlung emission in the inertial confinement fusion plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Habibi, M.; Oloumi, M.; Hosseinkhani, H.; Magidi, S. [Plasma and Fusion Research School, Nuclear Science and Technology Research Institute, Tehran (Iran, Islamic Republic of)

    2015-10-15

    A highly nonlinear parabolic partial differential equation that models the electron heat transfer process in laser inertial fusion has been solved numerically. The strong temperature dependence of the electron thermal conductivity and heat loss term (Bremsstrahlung emission) makes this a highly nonlinear process. In this case, an efficient numerical method is developed for the energy transport mechanism from the region of energy deposition into the ablation surface by a combination of the Crank-Nicolson scheme and the Newton-Raphson method. The quantitative behavior of the electron temperature and the comparison between analytic and numerical solutions are also investigated. For more clarification, the accuracy and conservation of energy in the computations are tested. The numerical results can be used to evaluate the nonlinear electron heat conduction, considering the released energy of the laser pulse at the Deuterium-Tritium (DT) targets and preheating by heat conduction ahead of a compression shock in the inertial confinement fusion (ICF) approach. (copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  14. The scattering of a bremsstrahlung radiation of electrons with energy 13 and 22 MeV from plane targets

    CERN Document Server

    Asatov, U T

    2002-01-01

    In the present work the characteristics of backward (90 sup d egbremsstrahlung radiation of electrons with energy 13 and 22 MeV with plane targets of different thickness from glass textolite, aluminium, iron, lead and their combination are investigated. The dependence of thickness of saturation of 'forward' scattered gamma radiation, a on angles of detection (theta sub s) and orientation (phi) of plane targets depending on a direction of probing beam was observed for the first time. For the first time, the numerical performances of beams of forward scattered gamma radiation from different targets were investigated and determined depending on their orientation and thickness. The new and corrected data on numerical performances of beams of the inverse scattered gamma radiation is obtained. The distinction in characteristics of beams of the scattered gamma radiation is s...

  15. CORONAL MAGNETIC FIELDS DERIVED FROM SIMULTANEOUS MICROWAVE AND EUV OBSERVATIONS AND COMPARISON WITH THE POTENTIAL FIELD MODEL

    Energy Technology Data Exchange (ETDEWEB)

    Miyawaki, Shun; Nozawa, Satoshi [Department of Science, Ibaraki University, Mito, Ibaraki 310-8512 (Japan); Iwai, Kazumasa; Shibasaki, Kiyoto [Nobeyama Solar Radio Observatory, National Astronomical Observatory of Japan, Minamimaki, Nagano 384-1305 (Japan); Shiota, Daikou, E-mail: shunmi089@gmail.com [Solar-Terrestrial Environment Laboratory, Nagoya University, Nagoya, Aichi 464-8601 (Japan)

    2016-02-10

    We estimated the accuracy of coronal magnetic fields derived from radio observations by comparing them to potential field calculations and the differential emission measure measurements using EUV observations. We derived line-of-sight components of the coronal magnetic field from polarization observations of the thermal bremsstrahlung in the NOAA active region 11150, observed around 3:00 UT on 2011 February 3 using the Nobeyama Radioheliograph at 17 GHz. Because the thermal bremsstrahlung intensity at 17 GHz includes both chromospheric and coronal components, we extracted only the coronal component by measuring the coronal emission measure in EUV observations. In addition, we derived only the radio polarization component of the corona by selecting the region of coronal loops and weak magnetic field strength in the chromosphere along the line of sight. The upper limits of the coronal longitudinal magnetic fields were determined as 100–210 G. We also calculated the coronal longitudinal magnetic fields from the potential field extrapolation using the photospheric magnetic field obtained from the Helioseismic and Magnetic Imager. However, the calculated potential fields were certainly smaller than the observed coronal longitudinal magnetic field. This discrepancy between the potential and the observed magnetic field strengths can be explained consistently by two reasons: (1) the underestimation of the coronal emission measure resulting from the limitation of the temperature range of the EUV observations, and (2) the underestimation of the coronal magnetic field resulting from the potential field assumption.

  16. Dynamical structure of magnetized dissipative accretion flow around black holes

    CERN Document Server

    Sarkar, Biplob

    2016-01-01

    We study the global structure of optically thin, advection dominated, magnetized accretion flow around black holes. We consider the magnetic field to be turbulent in nature and dominated by the toroidal component. With this, we obtain the complete set of accretion solutions for dissipative flows where bremsstrahlung process is regarded as the dominant cooling mechanism. We show that rotating magnetized accretion flow experiences virtual barrier around black hole due to centrifugal repulsion that can trigger the discontinuous transition of the flow variables in the form of shock waves. We examine the properties of the shock waves and find that the dynamics of the post-shock corona (PSC) is controlled by the flow parameters, namely viscosity, cooling rate and strength of the magnetic field, respectively. We separate the effective region of the parameter space for standing shock and observe that shock can form for wide range of flow parameters. We obtain the critical viscosity parameter that allows global accret...

  17. Double Compton and Cyclo-Synchrotron in Super-Eddington Disks, Magnetized Coronae, and Jets

    CERN Document Server

    McKinney, Jonathan C; Wielgus, Maciek; Narayan, Ramesh; Sadowski, Aleksander

    2016-01-01

    We present an extension to the general relativistic radiation magnetohydrodynamic code HARMRAD to account for emission and absorption by thermal cyclo-synchrotron, double Compton, bremsstrahlung, low-temperature OPAL opacities as well as Thomson and Compton scattering. We approximate the radiation field as a Bose-Einstein distribution and evolve it using the radiation number-energy-momentum conservation equations in order to track photon hardening. We perform various simulations to study how these extensions affect the radiative properties of magnetically-arrested disks accreting at Eddington to super-Eddington rates. We find that double Compton dominates bremsstrahlung in the disk within a radius of $r\\sim 15r_g$ (gravitational radii) at a hundred times the Eddington accretion rate, and within smaller radii at lower accretion rates. Double Compton and cyclo-synchrotron regulate radiation and gas temperatures in the corona, while cyclo-synchrotron regulates temperatures in the jet. Interestingly, as the accre...

  18. The significance of Bremsstrahlung SPECT/CT after yttrium-90 radioembolization treatment in the prediction of extrahepatic side effects

    Energy Technology Data Exchange (ETDEWEB)

    Ahmadzadehfar, Hojjat; Muckle, Marianne; Sabet, Amir; Biermann, Kim; Haslerud, Torjan; Biersack, Hans-Juergen; Ezziddin, Samer [University Hospital Bonn, Department of Nuclear Medicine, Bonn (Germany); Wilhelm, Kai [University Hospital Bonn, Department of Radiology, Bonn (Germany); Kuhl, Christiane [University Hospital Aachen, Department of Radiology, Aachen (Germany)

    2012-02-15

    Unwanted deposition of {sup 90}Y microspheres in organs other than the liver during radioembolization of liver tumours may cause severe side effects such as duodenal ulcer. The aim of this study was to evaluate the significance of posttherapy bremsstrahlung (BS) SPECT/CT images of the liver in comparison to planar and SPECT images in the prediction of radioembolization-induced extrahepatic side effects. A total of 188 radioembolization procedures were performed in 123 patients (50 women, 73 men) over a 2-year period. Planar, whole-body and BS SPECT/CT imaging were performed 24 h after treatment as a part of therapy work-up. Any focally increased extrahepatic accumulation was evaluated as suspicious. Clinical follow-up and gastroduodenoscopy served as reference standards. The studies were reviewed to evaluate whether BS SPECT/CT imaging was of benefit. In the light of anatomic data obtained from SPECT/CT, apparent extrahepatic BS in 43% of planar and in 52% of SPECT images proved to be in the liver and hence false-positive. The results of planar scintigraphy could not be analysed further since 12 images were not assessable due to high scatter artefacts. On the basis of the gastrointestinal (GI) complications and the results of gastroduodenoscopy, true-positive, true-negative, false-positive and false-negative results of BS SPECT and SPECT/CT imaging in the prediction of GI ulcers were determined. The sensitivity, specificity, positive and negative predictive values and the accuracy of SPECT and SPECT/CT in the prediction of GI ulcers were 13%, 88%, 8%, 92% and 82%, and 87%, 100%, 100%, 99% and 99%, respectively. Despite the low quality of BS images, BS SPECT/CT can be used as a reliable method to confirm the safe distribution of {sup 90}Y microspheres and in the prediction of GI side effects. (orig.)

  19. WE-E-18A-05: Bremsstrahlung of Laser-Plasma Interaction at KeV Temperature: Forward Dose and Attenuation Factors

    International Nuclear Information System (INIS)

    Purpose: To obtain an analytical empirical formula for the photon dose source term in forward direction from bremsstrahlung generated from laser-plasma accelerated electron beams in aluminum solid targets, with electron-plasma temperatures in the 10–100 keV energy range, and to calculate transmission factors for iron, aluminum, methacrylate, lead and concrete and air, materials most commonly found in vacuum chamber labs. Methods: Bremsstrahlung fluence is calculated from the convolution of thin-target bremsstrahlung spectrum for monoenergetic electrons and the relativistic Maxwell-Juettner energy distribution for the electron-plasma. Unattenuatted dose in tissue is calculated by integrating the photon spectrum with the mass-energy absorption coefficient. For the attenuated dose, energy dependent absorption coefficient, build-up factors and finite shielding correction factors were also taken into account. For the source term we use a modified formula from Hayashi et al., and we fitted the proportionality constant from experiments with the aid of the previously calculated transmission factors. Results: The forward dose has a quadratic dependence on electron-plasma temperature: 1 joule of effective laser energy transferred to the electrons at 1 m in vacuum yields 0,72 Sv per MeV squared of electron-plasma temperature. Air strongly filters the softer part of the photon spectrum and reduce the dose to one tenth in the first centimeter. Exponential higher energy tail of maxwellian spectrum contributes mainly to the transmitted dose. Conclusion: A simple formula for forward photon dose from keV range temperature plasma is obtained, similar to those found in kilovoltage x-rays but with higher dose per dissipated electron energy, due to thin target and absence of filtration

  20. Absolute sensitivity calibration of vacuum and extreme ultraviolet spectrometer systems and Z(eff) measurement based on bremsstrahlung continuum in HL-2A tokamak.

    Science.gov (United States)

    Zhou, Hangyu; Cui, Zhengying; Morita, Shigeru; Fu, Bingzhong; Goto, Motoshi; Sun, Ping; Dong, Chunfeng; Gao, Yadong; Xu, Yuan; Lu, Ping; Yang, Qingwei; Duan, Xuru

    2012-10-01

    A grazing-incidence flat-field extreme ultraviolet (EUV) spectrometer has been newly developed in HL-2A tokamak. Typical spectral lines are observed from intrinsic impurities of carbon, oxygen, iron, and extrinsic impurity of helium in the wavelength range of 20 Å-500 Å. Bremsstrahlung continuum is measured at different electron densities of HL-2A discharges to calibrate absolute sensitivity of the EUV spectrometer system and to measure effective ionic charge, Z(eff). The sensitivity of a vacuum ultraviolet (VUV) spectrometer system is also absolutely calibrated in overlapped wavelength range of 300 Å-500 Å by comparing the intensity between VUV and EUV line emissions. PMID:23126850

  1. Feasibility of bremsstrahlung dosimetry for direct dose estimation in patients undergoing treatment with {sup 90}Y-ibritumomab tiuxetan

    Energy Technology Data Exchange (ETDEWEB)

    Arrichiello, C.; Aloj, L.; Mormile, M.; D' Ambrosio, L.; Caraco, C.; De Martinis, F. [Istituto Nazionale per lo Studio e la Cura dei Tumori, Fondazione ' ' G. Pascale' ' , Nuclear Medicine Department, Napoli (Italy); Frigeri, F.; Arcamone, M.; Pinto, A. [Istituto Nazionale per lo Studio e la Cura dei Tumori, Fondazione ' ' G. Pascale' ' , Hematology-Oncology, Napoli (Italy); Stem Cells Transplantation Unit, Department of Hematology, Napoli (Italy); Lastoria, S. [Istituto Nazionale per lo Studio e la Cura dei Tumori, Fondazione ' ' G. Pascale' ' , Nuclear Medicine Department, Napoli (Italy); Istituto Nazionale per lo Studio e la Cura dei Tumori, Fondazione ' ' G. Pascale' ' , IRCCS, Napoli (Italy)

    2012-06-15

    on patient-specific dosimetry, the administered activity may be increased by an average factor of 2.4, indicating that most patients could be undertreated. The relative dosimetry approach based on planar imaging largely underestimates doses relative to reference values. Dosimetry based on planar bremsstrahlung imaging is not a dependable alternative to {sup 111}In dosimetry. (orig.)

  2. Neutrino emission in neutron matter from magnetic moment interactions

    CERN Document Server

    Jaikumar, P; Gale, C; Jaikumar, Prashanth; Gale, Charles

    2004-01-01

    Neutrino emission drives neutron star cooling for the first several hundreds of years after its birth. Given the low energy ($\\sim$ keV) nature of this process, one expects very few nonstandard particle physics contributions which could affect this rate. Requiring that any new physics contributions involve light degrees of freedom, one of the likely candidates which can affect the cooling process would be a nonzero magnetic moment for the neutrino. To illustrate, we compute the emission rate for neutrino pair bremsstrahlung in neutron-neutron scattering through photon-neutrino magnetic moment coupling. We also present analogous differential rates for neutrino scattering off nucleons and electrons that determine neutrino opacities in supernovae. Employing current upper bounds from collider experiments on the tau magnetic moment, we find that the neutrino emission rate can exceed the rate through neutral current electroweak interaction by a factor two, signalling the importance of new particle physics input to ...

  3. Characterisation of a MeV Bremsstrahlung x-ray source produced from a high intensity laser for high areal density object radiography

    Energy Technology Data Exchange (ETDEWEB)

    Courtois, C.; Compant La Fontaine, A.; Bazzoli, S.; Bourgade, J. L.; Gazave, J.; Lagrange, J. M.; Landoas, O.; Dain, L. Le; Pichoff, N. [CEA, DAM, DIF, F-91297 Arpajon (France); Edwards, R.; Aedy, C. [AWE Plc., Aldermaston, Reading RG7 4PR (United Kingdom); Mastrosimone, D.; Pien, G.; Stoeckl, C. [Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623 (United States)

    2013-08-15

    Results of an experiment to characterise a MeV Bremsstrahlung x-ray emission created by a short (<10 ps) pulse, high intensity (1.4 × 10{sup 19} W/cm{sup 2}) laser are presented. X-ray emission is characterized using several diagnostics; nuclear activation measurements, a calibrated hard x-ray spectrometer, and dosimeters. Results from the reconstructed x-ray energy spectra are consistent with numerical simulations using the PIC and Monte Carlo codes between 0.3 and 30 MeV. The intense Bremsstrahlung x-ray source is used to radiograph an image quality indicator (IQI) heavily filtered with thick tungsten absorbers. Observations suggest that internal features of the IQI can be resolved up to an external areal density of 85 g/cm{sup 2}. The x-ray source size, inferred by the radiography of a thick resolution grid, is estimated to be approximately 400 μm (full width half maximum of the x-ray source Point Spread Function)

  4. Measurement of the bremsstrahlung spectra generated from thick targets with =2–78 under the impact of 10 keV electrons

    Indian Academy of Sciences (India)

    Namita Yadav; Pragya Bhatt; Raj Singh; V S Subrahmanyam; R Shanker

    2010-04-01

    We present new experimental data on thick target bremsstrahlung spectra generated from the interaction of energetic electrons with bulk matter. The ‘photon yields’ in terms of double differential cross-sections (DDCS) are measured for pure elements of thick targets: Ti ( = 22), Ag ( = 47), W ( = 74) and Pt ( = 78) under the impact of 10 keV electrons. Comparison of DDCS obtained from the experimental data is made with those predicted by Monte-Carlo (MC) calculations using PENELOPE code. A close agreement between the experimental data and the MC calculations is found for all the four targets within the experimental error of 16%. Furthermore, the ratios of DDCS of bremsstrahlung photons emitted from Ag, W and Pt with those from Ti as a function of photon energy are examined with a relatively lower uncertainty of about 10% and they are compared with MC calculations. A satisfactory agreement is found between the experiment and the calculations within some normalizing factors. The variations of DDCS as a function of Z and of photon energy are also studied which show that the DDCS vary closely with Z; however, some deviations are observed for ‘tip’ photons emitted from high Z targets.

  5. ASCA View of the Supernova Remnant Gamma Cygni (G78.2+2.1) Bremsstrahlung X-ray Spectrum from Loss-flattened Electron Distribution

    CERN Document Server

    Uchiyama, Y; Aharonian, F A; Mattox, J R; Uchiyama, Yasunobu; Takahashi, Tadayuki; Aharonian, Felix; Mattox, John

    2002-01-01

    We perform X-ray studies of the shell-type supernova remnant (SNR) gamma-Cygni associated with the brightest EGRET unidentified source 3EG J2020+4017. In addition to the thermal emissions with characteristic temperature of kT = 0.5-0.9 keV, we found an extremely hard X-ray component from several clumps localized in the northern part of the remnant. This component is described by a power-law with a photon index of 0.8-1.5. Both the absolute flux and the spectral shape of the nonthermal X-rays cannot be explained by the synchrotron or inverse-Compton mechanisms. We argue that the unusually hard X-ray spectrum can be naturally interpreted in terms of nonthermal bremsstrahlung from Coulomb-loss-flattened electron distribution in dense environs with the gas density about 10 to 100 cm^-3 . For given spectrum of the electron population, the ratio of the bremsstrahlung X- and gamma-ray fluxes depends on the position of the ``Coulomb break'' in the electron spectrum. The bulk of gamma-rays detected by EGRET would come...

  6. Parametric interference effect in nonresonant spontaneous bremsstrahlung of an electron in the field of a nucleus and two pulsed laser waves

    Science.gov (United States)

    Lebed', A. A.; Padusenko, E. A.; Roshchupkin, S. P.; Dubov, V. V.

    2016-07-01

    Nonresonant spontaneous bremsstrahlung of an electron scattered by a nucleus in the field of two moderately strong pulsed waves is studied theoretically. The process is studied in detail within the interference kinematic region. This region is determined by scattering of particles in the same plane at predetermined angles, at which stimulated absorption and emission of photons of external pulsed waves by an electron occur in a correlated manner. It is shown that the probability of the partial process with correlated emission (absorption) by an electron of the equal number of photons of the both waves is of an order of the magnitude greater than the corresponding probability in any other scattering kinematics. The cross section of spontaneous bremsstrahlung in two pulsed waves may be two times greater than the cross section of a free-field process after summation over all stimulated processes of correlated emission and absorption. Obtained results may be experimentally verified, for example, by scientific facilities at sources of pulsed laser radiation (SLAC, FAIR, ELI, XCELS).

  7. Optimization of the image contrast in SPECT-CT bremsstrahlung imaging for Selective Internal Radiation Therapy of liver malignancies with Y-90 microspheres

    CERN Document Server

    Bonutti, Faustino; Magro, Giuseppe; Cecotti, Andrea; Della Schiava, Emanuele; Del Dò, Elena; Longo, Francesco; Herassi, Yassine; Bentayeb, Farida; Rossi, Marina; Ferretti, Guido; Geatti, Onelio; Padovani, Renato

    2015-01-01

    The quality of SPECT Bremsstrahlung images of patients treated with Y-90 is poor, mainly because of scattered radiation and collimator septa penetration. To minimize the latter effect, High Energy (HE) or Medium Energy (ME) collimators can be used. Scatter correction is not possible through the methods commonly used for the diagnostic radionuclides (Tc-99m, etc.) because the Bremsstrahlung radiation does not have distinct photopeaks, but a broad spectrum of energies ranging from zero to the maximum one detectable by the gamma-camera crystal is registered. Scatter radiation and collimator septa penetration affect the Contrast and the Contrast Recovery Coefficient (CRC) : our research focused on finding the best energy position for the acquisition window in order to maximize these parameters. To be guided in this finding, we first made a Monte Carlo (MC) simulation of a SPECT acquisition of a Y-90 cylindrical phantom and then we measured at different energies the Line Spread Function (LSF) of a linear Y-90 sour...

  8. Interacting Cosmic Rays with Molecular Clouds: A Bremsstrahlung Origin of Diffuse High Energy Emission from the Inner 2deg by 1deg of the Galactic Center

    CERN Document Server

    Yusef-Zadeh, F; Wardle, M; Tatischeff, V; Roberts, D; Cotton, W; Uchiyama, H; Nobukawa, M; Tsuru, T G; Heinke, C; Royster, M

    2012-01-01

    The high energy activity in the inner few degrees of the Galactic center is traced by diffuse radio, X-ray and gamma-ray emission. The physical relationship between different components of diffuse gas emitting at multiple wavelengths is a focus of this work. We first present radio continuum observations using Green Bank Telescope and model the nonthermal spectrum in terms of a broken power-law distribution of GeV electrons emitting synchrotron radiation. We show that the emission detected by Fermi is primarily due to nonthermal bremsstrahlung produced by the population of synchrotron emitting electrons in the GeV energy range interacting with neutral gas. The extrapolation of the electron population measured from radio data to low and high energies can also explain the origin of FeI 6.4 keV line and diffuse TeV emission, as observed with Suzaku, XMM-Newton, Chandra and the H.E.S.S. observatories. The inferred physical quantities from modeling multi-wavelength emission in the context of bremsstrahlung emission...

  9. Measurement of yields for the {sup 197}Au(γ,xn){sup 197-x}Au reactions induced by 2.5 GeV Bremsstrahlung

    Energy Technology Data Exchange (ETDEWEB)

    Hien, Nguyen Thi; Kim, Guinyun; Kim, Kwangsoo; Shahid, Muhammad; Zaman, Muhammah; Nadeem, Muhammad [Kyungpook National University, Daegu (Korea, Republic of); Khue, Pham Duc; Thanh, Kim Tien; Do, Nguyen Van [Vietnam Academy of Science and Technology, Hanoi (Viet Nam)

    2015-05-15

    Studies of high-energy nuclear reactions are of great important. It may help in deeper understanding of the reaction mechanisms and in extending of various fields of applications such as astrophysics, radiation physics, intense neutron source production and nuclear waste transmutation. The aim of the present work is to investigate the multineutron photonuclear on {sup 197}Au bombarded by 2.5 GeV Bremsstrahlung. Most of the photodisintegration products of gold with half-lives sufficient for the activity measurement. In this work, the necessary corrections were made in order to improve the accuracy of the experimental results The obtained experimental results are in good agreement with the calculated values. The yields for the {sup 197}Au(γ,xn){sup 197}-xAu reactions depend not only on the excitation energies but also on the number of neutrons ejected.

  10. Application of the photon-fluence scaling theorem to absorbed dose calorimetry for bremsstrahlung peak energy >1.02 MeV

    International Nuclear Information System (INIS)

    Application of the 'photon fluence scaling theorem' allows the ionization chamber to be placed at points in media where the photon fluence is the same, hence eliminating problems with energy response. The theorem is applicable to Compton scattered photons. For photon energies greater than 1.02 MeV, pair production alters the photon fluence in such a way as to invalidate the scaling theorem. In this report the effect of pair production is examined, so that a correction may be applied to the photon fluence scaling theorem. This correction extends application of the theorem for bremsstrahlung spectra up to at least 25 MeV peak energy. 10 refs., 4 tabs., 1 fig

  11. Measurement of isomeric-yield ratios of 109m,gPd and 115m,gCd with 50-, 60-, and 70-MeV bremsstrahlung

    Science.gov (United States)

    Rahman, Md. Shakilur; Lee, Manwoo; Kim, Kyung-Sook; Kim, Guinyun; Kim, Eunae; Cho, Moo-Hyun; Shvetshov, Valery; Khue, Pham Duc; Van Do, Nguyen

    2012-04-01

    The isomeric-yield ratios of 109m,gPd and 115m,gCd were measured by the activation method with uncollimated bremsstrahlung beams of 50-, 60-, and 70-MeV generated from an electron linear accelerator at Pohang Accelerator Laboratory. The induced activities in the irradiated foils were measured by the high-resolution γ-ray spectrometric system consisting of a high-purity germanium detector and a multichannel analyzer. The obtained isomeric-yield ratios in the formation of 109m,gPd and 115m,gCd are compared with the corresponding values found in the other experiments and the calculated values based on the statistical model code TALYS. The present results for 109m,gPd and 115m,gCd in this energy region are the first measurement.

  12. Influence of the transverse dimensions of colliding beams on processes of bremsstrahlung and production of e/sup +/e/sup -/ pairs

    Energy Technology Data Exchange (ETDEWEB)

    Kotkin, G.L.; Polityko, S.I.; Serbo, V.G.

    1985-09-01

    For high energies of colliding e/sup +/e/sup -/, ep, and ..gamma..e beams in processes of bremsstrahlung and production of e/sup +/e/sup -/ pairs, an important role is played by impact parameters much greater than the transverse dimensions of the beams. This leads to a decrease of the number of observed events in comparison with the standard calculations. Exact formulas and a number of convenient approximate formulas are obtained for the number of events in an arbitrary reaction with allowance for the finite dimensions of the beams. Concrete calculations are given for production of e/sup +/e/sup -/ pairs.The deviations from the standard calculations for e/sup +/e/sup -/ collisions under the conditions of LEP, SLC, and VLEPP are 1, 4, and 15%, respectively, and for ..gamma..e collisions under the conditions of SLC and VLEPP they are 20 and 35%, respectively.

  13. Low temperature in-situ measurements of FVP-300 type quartz - quartz optical fiber transmission in the Bremsstrahlung gamma irradiation field

    International Nuclear Information System (INIS)

    The aim of investigations was the study of spectral and relaxation characteristics of radiation induced absorption in the FVP-300 type quartz-quartz optical fibres (OF) which are used both as detector of charged particles and as collector of the induced Cherenkov radiation. The part of OF with the length l m turned in to ring of 5 cm of diameter directly, in thermostat, was irradiated by a bunch of Bremsstrahlung gamma - rays. (T=77 K, P=170 R/s, W=32 min). At the same time the other part of OF was used for transportation of probing light which has been detected by EPP 2000 deg. C model Miniature Fiber Optic Spectrometer. Tungstate target plate being irradiated by electrons beam of MT-22C model microthrone (frequency of 400 Hz at a current of 7 μA) was as Bremsstrahlung gamma irradiation source (average energy of 7 MeV). The OF transmission has been measured before, in-situ, and after stopping of irradiation at the temperature of liquid nitrogen. The result obtained enable us to calculate induced absorption spectra. The results of investigations are as follows: 1. The induced absorption spectra are characterized by several bands with the maximum at 560, 340 and 260 nm. 2. The induced absorption growth kinetic in the same for all bands and carriers two-stage character. 3. The relaxation of the induced absorption at temperature of liquid nitrogen is found out in the OF investigated. The investigation kinetics with a high degree of accuracy coincides for absorption canters of 560 and 340 nm. The results of investigation are discussed in terms of existing models of radiation defect formation in the quartz glass and data of low temperature thermoglow (TG). The analysis carried out will allow to serene a nature of nonstationary losses in the OF being in fields of ionizing radiations

  14. Observation of material, thickness, and bremsstrahlung x-ray intensity dependent effects in moderate and high Z targets in a gamma and x-ray LIDAR experiment

    Science.gov (United States)

    Zhang, Xiaodong; Ayaz-Maierhafer, Birsen; Laubach, Mitchell A.; Hayward, Jason P.

    2015-06-01

    A high energy gamma and x-ray LIDAR system consisting of a fast pulse (~50 ps, FWHM) LINAC and a Cherenkov detection system was used to investigate response differences among materials, their thicknesses, and bremsstrahlung x-ray intensities. The energies and pulse width of electrons used to produce bremsstrahlung x-rays were set at 20 or 40 MeV and 50 ps FWHM duration, respectively. The Cherenkov detector was built with a fused silica glass optically coupled to a 51 mm fast timing photomultiplier tube, which has an intrinsic energy threshold of 340.7 keV for Compton backscattered gammas. Such a fast detection system yields a coincidence resolving time of 93 ps FWHM, which is equivalent to a depth resolving capability of about 3 cm FWHM. The thicknesses of iron and lead targets were varied from 1 in. to 7 in. with a step of 1 in., and the thicknesses of DU were varied from 1/3 in. to 1 in. with a step of 1/3 in. The experimental results show that iron targets tend to produce a factor of five less observed x-rays and gammas, with less energetic photoelectron frequency distributions, compared with DU and lead targets for the same beam intensity and target thicknesses. Additionally, the self-shielding effect causes the lead to yield more gammas than the DU considering the experimental observation point. For the setup used in this study, a charge per pulse in the range of 1-2.5 nC yields the best resolving capability between the DU and lead targets.

  15. A Comparison of Laser-induced Bremsstrahlung and Laser Compton Scattering for (γ, n) Photo-transmutation of Hazardous Nuclear Waste

    Energy Technology Data Exchange (ETDEWEB)

    Rehman, Haseeb ur; Lee, Jiyoung; Kim, Yonghee [KAIST, Daejeon (Korea, Republic of)

    2015-10-15

    This paper also presents sensitivity analysis to yield the maximum possible photo-transmutation rates. In general the possibility of radionuclide transmutation using photo-neutron reaction is evaluated in this work. In this paper a detailed methodology to calculate transmutation reaction rates using Laser Induced Bremsstrahlung (LIB) and Laser Compton Scattering (LCS) has been discussed. The methodology was validated by comparing the calculated reaction rates against published data in publically accessed literatures. In the second half of the paper, the authors present a novel concept to narrow down the LCS photon spectrum to an energy range that matches with the resonance region of a particular radionuclide. This is particularly useful considering hazardous waste is usually a mix of different isotopes. As such, being able to tune the LCS photon into any narrow energy range so as to selectively transmute any particular isotope of interest in the hazardous waste mixture would be very desirable. LCS spectrum is highly sensitive to the electron beam energy, laser power, laser luminosity and Compton backscattering angle. From the results it is quite evident that LCS is much better option for the radionuclide transmutation as reaction rates for the LCS is much higher than LIB method even for very small laser power. It can be seen even for the optimistic reaction rate calculations with Bremsstrahlung method reaction rate is much lower than LCS case for 10 Hz repetition rate. If repetition rate of laser 100 Hz then LIB reaction rate has the same order of the magnitude as the reaction rate via LCS. Higher Laser Powers can yield very high transmutation rates.

  16. Magnetism and magnetic materials

    CERN Document Server

    Coey, J M D

    2010-01-01

    Covering basic physical concepts, experimental methods, and applications, this book is an indispensable text on the fascinating science of magnetism, and an invaluable source of practical reference data. Accessible, authoritative, and assuming undergraduate familiarity with vectors, electromagnetism and quantum mechanics, this textbook is well suited to graduate courses. Emphasis is placed on practical calculations and numerical magnitudes - from nanoscale to astronomical scale - focussing on modern applications, including permanent magnet structures and spin electronic devices. Each self-contained chapter begins with a summary, and ends with exercises and further reading. The book is thoroughly illustrated with over 600 figures to help convey concepts and clearly explain ideas. Easily digestible tables and data sheets provide a wealth of useful information on magnetic properties. The 38 principal magnetic materials, and many more related compounds, are treated in detail

  17. Particle transport in magnetized media around black holes and associated radiation

    CERN Document Server

    Vieyro, Florencia L

    2012-01-01

    Galactic black hole coronae are composed of a hot, magnetized plasma. The spectral energy distribution produced in this component of X-ray binaries can be strongly affected by different interactions between locally injected relativistic particles and the matter, radiation and magnetic fields in the source. We study the non-thermal processes driven by the injection of relativistic particles into a strongly magnetized corona around an accreting black hole. We compute in a self-consistent way the effects of relativistic bremsstrahlung, inverse Compton scattering, synchrotron radiation, and the pair-production/annihilation of leptons, as well as hadronic interactions. Our goal is to determine the non-thermal broadband radiative output of the corona. The set of coupled kinetic equations for electrons, positrons, protons, and photons are solved and the resulting particle distributions are computed self-consistently. The spectral energy distributions of transient events in X-ray binaries are calculated, as well as t...

  18. A thermally stable heating mechanism for the intracluster medium: turbulence, magnetic fields and plasma instabilities

    CERN Document Server

    Kunz, M W; Cowley, S C; Binney, J J; Sanders, J S

    2010-01-01

    We consider the problem of self-regulated heating and cooling in galaxy clusters and the implications for cluster magnetic fields and turbulence. Viscous heating of a weakly collisional magnetised plasma is regulated by the pressure anisotropy with respect to the local direction of the magnetic field. The intracluster medium is a high-beta plasma, where pressure anisotropies caused by the turbulent stresses and the consequent local changes in the magnetic field will trigger very fast microscale instabilities. We argue that the net effect of these instabilities will be to pin the pressure anisotropies at a marginal level, controlled by the plasma beta parameter. This gives rise to local heating rates that turn out to be comparable to the radiative cooling rates. Furthermore, we show that a balance between this heating and Bremsstrahlung cooling is thermally stable, unlike the often conjectured balance between cooling and thermal conduction. Given a sufficient (and probably self-regulating) supply of turbulent ...

  19. A FOURIER-TRANSFORMED BREMSSTRAHLUNG FLASH MODEL FOR THE PRODUCTION OF X-RAY TIME LAGS IN ACCRETING BLACK HOLE SOURCES

    International Nuclear Information System (INIS)

    Accreting black hole sources show a wide variety of rapid time variability, including the manifestation of time lags during X-ray transients, in which a delay (phase shift) is observed between the Fourier components of the hard and soft spectra. Despite a large body of observational evidence for time lags, no fundamental physical explanation for the origin of this phenomenon has been presented. We develop a new theoretical model for the production of X-ray time lags based on an exact analytical solution for the Fourier transform describing the diffusion and Comptonization of seed photons propagating through a spherical corona. The resulting Green's function can be convolved with any source distribution to compute the associated Fourier transform and time lags, hence allowing us to explore a wide variety of injection scenarios. We show that thermal Comptonization is able to self-consistently explain both the X-ray time lags and the steady-state (quiescent) X-ray spectrum observed in the low-hard state of Cyg X-1. The reprocessing of bremsstrahlung seed photons produces X-ray time lags that diminish with increasing Fourier frequency, in agreement with the observations for a wide range of sources

  20. Vertical profile of the environmental gamma-ray in Kashiwazaki Kariwa area. Detection of bremsstrahlung X-ray generated by winter thunderstorms

    International Nuclear Information System (INIS)

    Cumulative dose measurements have been performed at the points from 1 m to 117 m above the ground on the arrester tower located at the site of the Kashiwazaki Kariwa nuclear power station using radiophotoluminescence glass dosimeter (RPLD) and thermoluminescence dosimeter (TLD). From the measurement results, the mean dose rates both from RPLD and TLD gradually decrease with height in summer season. On the other hand, the vertical profile of upper regions showed in the reverse attenuation in winter season. It was assumed that the increasing trend of dose rates with height is caused by some external radiation source peculiar to winter season. In this winter, many thunderstorms occurred and dose rates from both NaI(Tl) and ionization chamber (IC) detectors increased occasionally at monitoring stations. According to the Monte Carlo calculation of the behaviour of electrons and photons in the model thundercloud, it was suggested that bremsstrahlung X-rays generated at high altitude has been attributed to the radiation source. (author)

  1. Initial-state bremsstrahlung versus final-state hydrodynamic sources of azimuthal harmonics in p+A at RHIC and LHC

    International Nuclear Information System (INIS)

    Recent pT<2 GeV azimuthal correlation data from the Beam Energy Scan (BES) and d+Au runs at RHIC/BNL and, especially, the surprising similarity of 2ℓ=2,4,⋯-particle cummulant azimuthal n=2,3,4,5 harmonics, vn{2ℓ}(pT), in p+Pb and Pb+Pb at LHC have challenged the uniqueness of local equilibrium “perfect fluid” interpretations of those data. We report results derived in [1] on azimuthal harmonics arising from non-equilibrium initial-state non-abelian “wave interference” effects predicted by perturbative QCD gluon bremsstrahlung and sourced by Color Scintillation Arrays (CSA) of color antennas. CSA are naturally identified with multiple projectile and target beam jets produced in inelastic p+A reactions. We find a remarkable similarity between azimuthal harmonics sourced by initial state CSA and those predicted with final state perfect fluid models of high energy p+A reactions. The question of which mechanism dominates in p+A and A+A remains open at this time

  2. Electronic temperature measurement on the deca II plasma using the Bremsstrahlung; Mesure de la temperature electronique du plasma de deca II par etude du rayonnement de freinage

    Energy Technology Data Exchange (ETDEWEB)

    Dumas, A. [Commissariat a l' Energie Atomique, Fontenay-aux-Roses (France). Centre d' Etudes Nucleaires

    1967-06-01

    The electronic temperature of the DECA II machine's plasma is determined by studying the Bremsstrahlung. Two types of detectors are used for this measurement, a set scintillator-photo-multiplicator and a photoelectric effect detector with a massive silver target. The method used is the classical 'absorbent method', The absorbents used are thin formvar foils whose thickness is between 600 and 12 500 angstrom. The measurements done in two different working conditions of the DECA II machine have given: Te {approx_equal} 200 eV in the first case and Te {approx_equal} 70 eV in the second case. (author) [French] Nous avons determine la temperature electronique du plasma de la machine DECA II par l'etude du rayonnement de freinage. Pour cette mesure nous avons utilise deux types de detecteurs: des ensembles scintillateur-photomultiplicateur et un detecteur a effet photoelectrique a cible massive en argent. La methode utilisee pour cette mesure est la classique methode des absorbants. Nous avons utilise des feuilles de format tres mince (de 600 a 12 500 angstrom) comme absorbant. Les mesures faites dans deux regimes de travail differents de la machine DECA II nous ont conduit a: Te {approx_equal} 200 eV dans un cas et Te {approx_equal} eV dans l'autre cas. (auteur)

  3. Assay methods for U-238, Th-232, and Pb-210 in lead and calibration of Bi-210 bremsstrahlung emission from lead

    CERN Document Server

    Orrell, John L; Arnquist, Isaac J; Eggemeyer, Tere A; Glasgow, Brian D; Hoppe, Eric W; Keillor, Martin E; Morley, Shannon M; Myers, Allan W; Overman, Cory T; Shaff, Sarah M; Thommasson, Kimbrelle S

    2015-01-01

    Assay methods for measuring 238U, 232Th, and 210Pb concentrations in refined lead are presented. The 238U and 232Th concentrations are determined using isotope dilution inductively coupled plasma mass spectrometry (ID-ICP-MS) after anion exchange column separation of dissolved lead samples. The 210Pb concentration is inferred through {\\alpha}-spectroscopy of a daughter isotope, 210Po, after chemical precipitation separation on dissolved lead samples. Subsequent to the 210Po {\\alpha}-spectroscopy assay, a method for evaluating 210Pb concentrations in solid lead samples was developed via measurement of bremsstrahlung radiation from \\b{eta}-decay of a daughter isotope, 210Bi, by employing a 14-crystal array of high purity germanium (HPGe) detectors. Ten sources of refined lead were assayed. The 238U concentrations were <34 microBq/kg and the 232Th concentrations ranged <0.6-15 microBq/kg, as determined by the ICP-MS assay method. The 210Pb concentrations ranged from ~0.1-75 Bq/kg, as inferred by the 210Po ...

  4. Initial-State Bremsstrahlung versus Final-State Hydrodynamic Sources of Azimuthal Harmonics in p+A at RHIC and LHC

    CERN Document Server

    Gyulassy, Miklos; Vitev, Ivan; Biro, Tamas S

    2014-01-01

    Recent pT<2~GeV azimuthal correlation data from the Beam Energy Scan (BES) and D+Au runs at RHIC/BNL and, especially, the surprising similarity of azimuthal $v_n\\{2m\\}(p_T)$ ``transeverse flow'' harmonics in $p+Pb$ and $Pb+Pb$ at LHC have challenged the uniqueness of local equilibrium ``perfect fluid'' interpretations of those data. We report results at QM14 on azimuthal harmonics associated with initial-state non-abelian ``wave interference'' effects predicted by perturbative QCD gluon bremsstrahlung and sourced by Color Scintillation Arrays (CSA) of color antennas. CSA are naturally identified with multiple projectile and target beam jets produced in inelastic p+A reactions. We find a remarkable similarity between azimuthal harmonics sourced by initial state CSA and those predicted with final state perfect fluid models of high energy p+A reactions. The question of which mechanism dominates in $p+A$ and $A+A$ remains open at this time.

  5. Initial-state bremsstrahlung versus final-state hydrodynamic sources of azimuthal harmonics in p+A at RHIC and LHC

    Energy Technology Data Exchange (ETDEWEB)

    Gyulassy, M. [MTA WIGNER Research Centre for Physics, RMI, Budapest (Hungary); Department of Physics, Columbia University, New York, NY 10027 (United States); Levai, P. [MTA WIGNER Research Centre for Physics, RMI, Budapest (Hungary); Vitev, I. [Theoretical Division, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Biró, T.S. [MTA WIGNER Research Centre for Physics, RMI, Budapest (Hungary)

    2014-11-15

    Recent p{sub T}<2 GeV azimuthal correlation data from the Beam Energy Scan (BES) and d+Au runs at RHIC/BNL and, especially, the surprising similarity of 2ℓ=2,4,⋯-particle cummulant azimuthal n=2,3,4,5 harmonics, v{sub n}{2ℓ}(p{sub T}), in p+Pb and Pb+Pb at LHC have challenged the uniqueness of local equilibrium “perfect fluid” interpretations of those data. We report results derived in [1] on azimuthal harmonics arising from non-equilibrium initial-state non-abelian “wave interference” effects predicted by perturbative QCD gluon bremsstrahlung and sourced by Color Scintillation Arrays (CSA) of color antennas. CSA are naturally identified with multiple projectile and target beam jets produced in inelastic p+A reactions. We find a remarkable similarity between azimuthal harmonics sourced by initial state CSA and those predicted with final state perfect fluid models of high energy p+A reactions. The question of which mechanism dominates in p+A and A+A remains open at this time.

  6. The optical/UV excess of X-ray dim isolated neutron star:bremsstrahlung emission from a strange star plasma atmosphere

    CERN Document Server

    Wang, Weiyang; Tong, Hao; Ge, Mingyu; Li, Zhaosheng; Men, Yunpeng; Xu, Renxin

    2016-01-01

    X-ray dim isolated neutron stars (XDINSs) are characterized by Planckian spectra in X-ray bands, but show optical/ultraviolet(UV) excesses which are the measured photometry exceeding that extrapolated from X-ray spectra. To solve this problem, a radiative model of bremsstrahlung emission from a plasma atmosphere is constructed in the regime of strange (quark-cluster) star. The plasma atmosphere is supposed to be of two-temperature, formed and maintained by the ISM-accreted matter which is bound on a star's surface because of the so-called strangeness barrier. All the seven XDINS spectra could be well fitted by the radiative model, from optical/UV to X-ray bands. The fitted radiation radii of XDINSs are from 7 to 13 km, while the modelled electron temperatures are between 50 and 250 eV, except RX J0806.4$-$4123 with a radiation radius $\\sim 3$ km, indicating that this source could be a low-mass strange star candidate.

  7. Coherent Bremsstrahlung, Coherent Pair Production, Birefringence and Polarimetry in the 20-170 GeV energy range using aligned crystals

    CERN Document Server

    Apyan, A; Badelek, B; Ballestrero, S; Biino, C; Birol, I; Cenci, P; Connell, S H; Eichblatt, S; Fonseca, T; Freund, A; Gorini, B; Groess, R; Ispirian, K; Ketel, T; Kononets, Y V; López, A; Mangiarotti, A; Sellschop, J P Friedel; Shieh, M; Sona, P; Strakhovenko, V M; Uggerhøj, U; Uggerhøj, Erik; Van Rens, B; Velasco, M; Vilakazi, Z Z; Wessely, O; Ünel, G; Kononets, Yu V

    2008-01-01

    The processes of coherent bremsstrahlung (CB) and coherent pair production (CPP) based on aligned crystal targets have been studied in the energy range 20-170 GeV. The experimental arrangement allowed these phenomena as well as their polarization dependence to be evaluated under conditions where single-photon cross-sections could be measured. This proved very important as the theoretical description of CB and CPP is an area of active theoretical debate and development. The theoretical approach used in this paper predicts both the cross sections and polarization observables very well for the experimental conditions investigated, indicating that the understanding of CB and CPP is reliable up to energies of 170 GeV. A birefringence effect in CPP was studied and it was demonstrated this enabled new technologies for high energy photon beam optics, such as polarimeters (for both linear and circular polarization) and phase plates. We also present new results regarding the features of coherent high energy photon emis...

  8. Coherent Bremsstrahlung effect observed during STEM analysis of dopant distribution in silicon devices using large area silicon drift EDX detectors and high brightness electron source.

    Science.gov (United States)

    Pantel, R

    2011-11-01

    In this paper, during dopant analysis of silicon devices, we have observed a phenomenon generally neglected in EDX analysis: the coherent Bremsstrahlung (CB). We discussed the reason why and came to the conclusion that the analytical TEM used for these experiments presents a configuration and performances, which makes this equipment very sensitive to the CB effect. This is due to large collection solid angle and high counting rate of the four silicon drift EDX detectors (SDD), a high brightness electron source providing large probe current and moreover a geometry favorable to on axis crystal observations. We analyzed silicon devices containing Si [110] and Si [100] crystal areas at different energies (80-120-200keV). We also observed relaxed SiGe (27 and 40at% of Ge). The CB effect, whose intensity is maximum near zone axis beam alignment, manifests as characteristic broad peaks present in the X-ray spectrum background. The peak energies are predicted by a simple formula deduced for the CB models found in the literature and that we present simply. We evaluate also the CB peak intensities and discuss the importance of this effect on the detection and quantification traces of impurities. The CB peaks also give information on the analyzed crystal structure (measurement of the periodicity along the zone axis) and allow, in every particular experiment or system, to determine the median take off angle of the EDX detectors. PMID:21946001

  9. Neodymium Magnets.

    Science.gov (United States)

    Wida, Sam

    1992-01-01

    Uses extremely strong neodymium magnets to demonstrate several principles of physics including electromagnetic induction, Lenz's Law, domain theory, demagnetization, the Curie point, and magnetic flux lines. (MDH)

  10. Magnetic Levitation.

    Science.gov (United States)

    Rossing, Thomas D.; Hull, John R.

    1991-01-01

    Discusses the principles of magnetic levitation presented in the physics classroom and applied to transportation systems. Topics discussed include three classroom demonstrations to illustrate magnetic levitation, the concept of eddy currents, lift and drag forces on a moving magnet, magnetic levitation vehicles, levitation with permanent magnets…

  11. Magnetic Spinner

    Science.gov (United States)

    Ouseph, P. J.

    2006-01-01

    A science toy sometimes called the "magnetic spinner" is an interesting class demonstration to illustrate the principles of magnetic levitation. It can also be used to demonstrate Faraday's law and a horizontally suspended physical pendulum. The levitated part contains two circular magnets encased in a plastic housing. Each magnet stays…

  12. Magnetic Nanocapsules

    Institute of Scientific and Technical Information of China (English)

    Zhidong ZHANG

    2007-01-01

    A brief review on recent advances in the area of the magnetic nanocapsules is given. The most applicable nanoencapsulation procedures are introduced, which include: (1) physical techniques such as arc-discharge,evaporating, etc.; (2) chemical techniques such as chemical vapor deposition, solid-state reactions, etc. The structure and magnetic properties of various nanocapsules with different core/shell structures are studied in details, for possibly applications in magnetic recording, magnetic refrigerator, magnetic fluids, superconductors and medicine.

  13. Coherent Bremsstrahlung effect observed during STEM analysis of dopant distribution in silicon devices using large area silicon drift EDX detectors and high brightness electron source

    International Nuclear Information System (INIS)

    In this paper, during dopant analysis of silicon devices, we have observed a phenomenon generally neglected in EDX analysis: the coherent Bremsstrahlung (CB). We discussed the reason why and came to the conclusion that the analytical TEM used for these experiments presents a configuration and performances, which makes this equipment very sensitive to the CB effect. This is due to large collection solid angle and high counting rate of the four silicon drift EDX detectors (SDD), a high brightness electron source providing large probe current and moreover a geometry favorable to on axis crystal observations. We analyzed silicon devices containing Si [110] and Si [100] crystal areas at different energies (80–120–200 keV). We also observed relaxed SiGe (27 and 40 at% of Ge). The CB effect, whose intensity is maximum near zone axis beam alignment, manifests as characteristic broad peaks present in the X-ray spectrum background. The peak energies are predicted by a simple formula deduced for the CB models found in the literature and that we present simply. We evaluate also the CB peak intensities and discuss the importance of this effect on the detection and quantification traces of impurities. The CB peaks also give information on the analyzed crystal structure (measurement of the periodicity along the zone axis) and allow, in every particular experiment or system, to determine the median take off angle of the EDX detectors. -- Highlights: ► STEM EDX dopant distribution analysis (As and P) in Si devices is carried out. ► High brightness electron source and four EDX Silicon Drift detectors are used. ► The obtained signal dynamics (four decades) allows detection down to 0.01 at%. ► During silicon axis analysis coherent Bremmsstrahlung is observed. ► This effect is studied at different energies and Si crystal orientations.

  14. Dynamical structure of magnetized dissipative accretion flow around black holes

    Science.gov (United States)

    Sarkar, Biplob; Das, Santabrata

    2016-09-01

    We study the global structure of optically thin, advection dominated, magnetized accretion flow around black holes. We consider the magnetic field to be turbulent in nature and dominated by the toroidal component. With this, we obtain the complete set of accretion solutions for dissipative flows where bremsstrahlung process is regarded as the dominant cooling mechanism. We show that rotating magnetized accretion flow experiences virtual barrier around black hole due to centrifugal repulsion that can trigger the discontinuous transition of the flow variables in the form of shock waves. We examine the properties of the shock waves and find that the dynamics of the post-shock corona (PSC) is controlled by the flow parameters, namely viscosity, cooling rate and strength of the magnetic field, respectively. We separate the effective region of the parameter space for standing shock and observe that shock can form for wide range of flow parameters. We obtain the critical viscosity parameter that allows global accretion solutions including shocks. We estimate the energy dissipation at the PSC from where a part of the accreting matter can deflect as outflows and jets. We compare the maximum energy that could be extracted from the PSC and the observed radio luminosity values for several supermassive black hole sources and the observational implications of our present analysis are discussed.

  15. Neutrino emission in neutron matter from magnetic moment interactions

    International Nuclear Information System (INIS)

    Neutrino emission drives neutron star cooling for the first several hundreds of years after its birth. Given the low-energy (∼keV) nature of this process, one expects very few nonstandard particle-physics contributions which could affect this rate. Requiring that any new physics contributions involve light degrees of freedom, one of the likely candidates which can affect the cooling process would be a nonzero magnetic moment for the neutrino. To illustrate, we compute the emission rate for neutrino pair bremsstrahlung in neutron-neutron scattering through photon-neutrino magnetic moment coupling. We also present analogous differential rates for neutrino scattering off nucleons and electrons that determine neutrino opacities in supernovae. Employing current upper bounds from collider experiments on the τ magnetic moment, we find that the neutrino emission rate can exceed the rate through neutral current electroweak interaction by a factor 2, signaling the importance of new particle physics input to a standard calculation of relevance to neutron star cooling. However, astrophysical bounds on the neutrino magnetic moment imply smaller effects

  16. Development of an efficient scanning and purging magnet system for IMRT with narrow high energy photon beams

    Science.gov (United States)

    Andreassen, Björn; Svensson, Roger; Holmberg, Rickard; Danared, Håkan; Brahme, Anders

    2009-12-01

    Due to the clinical advantages of Intensity Modulated Radiation Therapy (IMRT) high flexibility and accuracy in intensity modulated dose delivery is desirable to really maximize treatment outcome. Although it is possible to deliver IMRT by using broad beams in combination with dynamic multileaf collimation the process is rather time consuming and inefficient. By using narrow scanned high energy photon beams the treatment outcome can be improved, the treatment time reduced and accurate 3D in vivo dose delivery monitoring is possible by PET-CT based dose delivery imaging of photo nuclear reactions in human tissues. Narrow photon beams can be produced by directing a low emittance high energy electron beam on a thin target, and then cleaning the therapeutic photon beam from transmitted high energy electrons, and photon generated charged leptons, with a dedicated purging magnet placed directly downstream of the target. To have an effective scanning and purging magnet system the purging magnet should be placed immediately after the bremsstrahlung target to deflect the transmitted electrons to an efficient electron stopper. In the static electron stopper the electrons should be safely collected independent of the desired direction of the therapeutic scanned photon beam. The SID (Source to Isocenter Distance) should preferably be short while retaining the ability to scan over a large area on the patient and consequently there are severe requirements both on the strength and the geometry of the scanning and purging magnets. In the present study an efficient magnet configuration with a purging and scanning magnet assembly is developed for electron energies in the 50-75 MeV range and a SID of 75 cm. For a bremsstrahlung target of 3 mm Be these electron energies produce a photon beam of 25-17 mm FWHM (Full Width Half Maximum) at a SID of 75 cm. The magnet system was examined both in terms of the efficiency in scanning the narrow bremsstrahlung beam and the deflection of

  17. Development of an efficient scanning and purging magnet system for IMRT with narrow high energy photon beams

    International Nuclear Information System (INIS)

    Due to the clinical advantages of Intensity Modulated Radiation Therapy (IMRT) high flexibility and accuracy in intensity modulated dose delivery is desirable to really maximize treatment outcome. Although it is possible to deliver IMRT by using broad beams in combination with dynamic multileaf collimation the process is rather time consuming and inefficient. By using narrow scanned high energy photon beams the treatment outcome can be improved, the treatment time reduced and accurate 3D in vivo dose delivery monitoring is possible by PET-CT based dose delivery imaging of photo nuclear reactions in human tissues. Narrow photon beams can be produced by directing a low emittance high energy electron beam on a thin target, and then cleaning the therapeutic photon beam from transmitted high energy electrons, and photon generated charged leptons, with a dedicated purging magnet placed directly downstream of the target. To have an effective scanning and purging magnet system the purging magnet should be placed immediately after the bremsstrahlung target to deflect the transmitted electrons to an efficient electron stopper. In the static electron stopper the electrons should be safely collected independent of the desired direction of the therapeutic scanned photon beam. The SID (Source to Isocenter Distance) should preferably be short while retaining the ability to scan over a large area on the patient and consequently there are severe requirements both on the strength and the geometry of the scanning and purging magnets. In the present study an efficient magnet configuration with a purging and scanning magnet assembly is developed for electron energies in the 50-75 MeV range and a SID of 75 cm. For a bremsstrahlung target of 3 mm Be these electron energies produce a photon beam of 25-17 mm FWHM (Full Width Half Maximum) at a SID of 75 cm. The magnet system was examined both in terms of the efficiency in scanning the narrow bremsstrahlung beam and the deflection of

  18. Model atmospheres and radiation of magnetic neutron stars. I - The fully ionized case

    Science.gov (United States)

    Shibanov, Iu. A.; Zavlin, V. E.; Pavlov, G. G.; Ventura, J.

    1992-01-01

    Model neutron star atmospheres are calculated for typical cooling stars with a strong magnetic field and effective temperatures of 10 exp 5 to 10 exp 6 K. The effect of anisotropic photon diffusion in two normal modes are examined under the assumption that the opacity is due solely to the bremsstrahlung and Thomson scattering processes under conditions of LTE that are expected to prevail at the temperatures and densities obtained. The main aspects of anisotropic photon diffusion, and an original procedure for calculating model atmospheres and emitted spectra are discussed. Representative calculated spectra are given, and it is found that the hard spectral excess characterizing the nonmagnetic case, while still present, becomes less prominent in the presence of magnetic fields in the range of 10 exp 11 to 10 exp 13 G.

  19. Photo-neutron reaction cross-sections for natMo in the bremsstrahlung end-point energies of 12-16 and 45-70 MeV

    Science.gov (United States)

    Naik, H.; Kim, G. N.; Kapote Noy, R.; Schwengner, R.; Kim, K.; Zaman, M.; Shin, S. G.; Gey, Y.; Massarczyk, R.; John, R.; Junghans, A.; Wagner, A.; Cho, M.-H.

    2016-07-01

    The natMo( γ, xn)90, 91, 99Mo reaction cross-sections were experimentally determined for the bremsstrahlung end-point energies of 12, 14, 16, 45, 50, 55, 60 and 70MeV by activation and off-line γ -ray spectrometric technique and using the 20MeV electron linac (ELBE) at the Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Dresden, Germany, and the 100MeV electron linac at the Pohang Accelerator Laboratory (PAL), Pohang, Korea. The natMo( γ, xn)88, 89, 90, 91, 99Mo reaction cross-sections as a function of photon energy were also calculated using the computer code TALYS 1.6. The flux-weighted average cross-sections were obtained from the literature data and the calculated values of TALYS based on mono-energetic photons and are found to be in general agreement with the present results. The flux-weighted average experimental and theoretical cross-sections for the natMo( γ, xn)88, 89, 90, 91, 99Mo reactions increase with the bremsstrahlung end-point energy, which indicates the role of excitation energy. After a certain energy, the individual natMo( γ, xn) reaction cross-sections decrease with the increase of bremsstrahlung energy due to opening of other reactions, which indicates sharing of energy in different reaction channels. The 100Mo( γ, n) reaction cross-section is important for the production of 99Mo , which is a probable alternative to the 98Mo(n, γ) and 235U(n, f ) reactions.

  20. Measurement of flux-weighted average cross-sections and isomeric yield ratios for 103Rh(γ,xn) reactions in the bremsstrahlung end-point energies of 55 and 60 MeV

    Science.gov (United States)

    Shakilur Rahman, Md.; Kim, Kwangsoo; Kim, Guinyun; Naik, Haladhara; Nadeem, Muhammad; Thi Hien, Nguyen; Shahid, Muhammad; Yang, Sung-Chul; Cho, Young-Sik; Lee, Young-Ouk; Shin, Sung-Gyun; Cho, Moo-Hyun; Woo Lee, Man; Kang, Yeong-Rok; Yang, Gwang-Mo; Ro, Tae-Ik

    2016-07-01

    We measured the flux-weighted average cross-sections and the isomeric yield ratios of 99m, g, 100m, g, 101m, g, 102m, gRh in the 103Rh( γ, xn) reactions with the bremsstrahlung end-point energies of 55 and 60MeV by the activation and the off-line γ-ray spectrometric technique, using the 100MeV electron linac at the Pohang Accelerator Laboratory (PAL), Korea. The flux-weighted average cross-sections were calculated by using the computer code TALYS 1.6 based on mono-energetic photons, and compared with the present experimental data. The flux-weighted average cross-sections of 103Rh( γ, xn) reactions in intermediate bremsstrahlung energies are the first time measurement and are found to increase from their threshold value to a particular value, where the other reaction channels open up. Thereafter, it decreases with bremsstrahlung energy due to its partition in different reaction channels. The isomeric yield ratios (IR) of 99m, g, 100m, g, 101m, g, 102m, gRh in the 103Rh( γ, xn) reactions from the present work were compared with the literature data in the 103Rh(d, x), 102-99Ru(p, x) , 103Rh( α, αn) , 103Rh( α, 2p3n) , 102Ru(3He, x), and 103Rh( γ, xn) reactions. It was found that the IR values of 102, 101, 100, 99Rh in all these reactions increase with the projectile energy, which indicates the role of excitation energy. At the same excitation energy, the IR values of 102, 101, 100, 99Rh are higher in the charged particle-induced reactions than in the photon-induced reaction, which indicates the role of input angular momentum.

  1. Magnetic Reconnection

    NARCIS (Netherlands)

    Schep, T. J.

    1994-01-01

    This lecture deals with the concept of magnetic field lines and with the conservation of magnetic flux. In high temperature fusion devices like tokamaks flux conservation can be violated and reconnection can occur at closed magnetic field lines. Reconnection processes lead to changes in the global t

  2. Superconducting magnets

    Energy Technology Data Exchange (ETDEWEB)

    1994-08-01

    This report discusses the following topics on superconducting magnets: D19B and -C: The next steps for a record-setting magnet; D20: The push beyond 10 T: Beyond D20: Speculations on the 16-T regime; other advanced magnets for accelerators; spinoff applications; APC materials development; cable and cabling-machine development; and high-{Tc} superconductor at low temperature.

  3. Exact Bremsstrahlung and effective couplings

    Science.gov (United States)

    Mitev, Vladimir; Pomoni, Elli

    2016-06-01

    We calculate supersymmetric Wilson loops on the ellipsoid for a large class of mathcal{N} = 2 SCFT using the localization formula of Hama and Hosomichi. From them we extract the radiation emitted by an accelerating heavy probe quark as well as the entanglement entropy following the recent works of Lewkowycz-Maldacena and Fiol-Gerchkovitz-Komargodski. Comparing our results with the mathcal{N} = 4 SYM ones, we obtain interpolating functions f ( g 2) such that a given mathcal{N} = 2 SCFT observable is obtained by replacing in the corresponding mathcal{N} = 4 SYM result the coupling constant by f ( g 2). These "exact effective couplings" encode the finite, relative renormalization between the mathcal{N} = 2 and the mathcal{N} = 4 gluon propagator and they interpolate between the weak and the strong coupling. We discuss the range of their applicability.

  4. Brane Bremsstrahlung in DBI Inflation

    CERN Document Server

    Brax, Philippe

    2010-01-01

    We consider the effect of trapped branes on the evolution of a test brane whose motion generates DBI inflation along a warped throat. The coupling between the inflationary brane and a trapped brane leads to the radiation of non-thermal particles on the trapped brane. We calculate the Gaussian spectrum of the radiated particles and their backreaction on the DBI motion of the inflationary brane. Radiation occurs for momenta lower than the speed of the test brane when crossing the trapped brane. The slowing down effect is either due to a parametric resonance when the interaction time is small compared to the Hubble time or a tachyonic resonance when the interaction time is large. In both cases the motion of the inflationary brane after the interaction is governed by a chameleonic potential,which tends to slow it down. We find that a single trapped brane can hardly slow down a DBI inflaton whose fluctuations lead to the Cosmic Microwave Background spectrum. A more drastic effect is obtained when the DBI brane enc...

  5. Exact Bremsstrahlung and effective couplings

    Energy Technology Data Exchange (ETDEWEB)

    Mitev, Vladimir [Mainz Univ. (Germany). Inst. fuer Physik, WA THEP; Humboldt-Univ. Berlin (Germany). Inst. fuer Mathematik und Inst. fuer Physik; Pomoni, Elli [DESY Hamburg (Germany). Theory Group; National Technical Univ., Athens (Greece). Physics Div.

    2015-11-15

    We calculate supersymmetric Wilson loops on the ellipsoid for a large class of N=2 SCFT using the localization formula of Hama and Hosomichi. From them we extract the radiation emitted by an accelerating heavy probe quark as well as the entanglement entropy following the recent works of Lewkowycz-Maldacena and Fiol-Gerchkovitz-Komargodski. Comparing our results with the N=4 SYM ones, we obtain interpolating functions f(g{sup 2}) such that a given N=2 SCFT observable is obtained by replacing in the corresponding N=4 SYM result the coupling constant by f(g{sup 2}). These ''exact effective couplings'' encode the finite, relative renormalization between the N = 2 and the N = 4 gluon propagator, they interpolate between the weak and the strong coupling. We discuss the range of their applicability.

  6. Exact Bremsstrahlung and effective couplings

    International Nuclear Information System (INIS)

    We calculate supersymmetric Wilson loops on the ellipsoid for a large class of N=2 SCFT using the localization formula of Hama and Hosomichi. From them we extract the radiation emitted by an accelerating heavy probe quark as well as the entanglement entropy following the recent works of Lewkowycz-Maldacena and Fiol-Gerchkovitz-Komargodski. Comparing our results with the N=4 SYM ones, we obtain interpolating functions f(g2) such that a given N=2 SCFT observable is obtained by replacing in the corresponding N=4 SYM result the coupling constant by f(g2). These ''exact effective couplings'' encode the finite, relative renormalization between the N = 2 and the N = 4 gluon propagator, they interpolate between the weak and the strong coupling. We discuss the range of their applicability.

  7. Exact Bremsstrahlung and Effective Couplings

    CERN Document Server

    Mitev, Vladimir

    2015-01-01

    We calculate supersymmetric Wilson loops on the ellipsoid for a large class of $\\mathcal{N}=2$ SCFT using the localization formula of Hama and Hosomichi. From them we extract the radiation emitted by an accelerating heavy probe quark as well as the entanglement entropy following the recent works of Lewkowycz-Maldacena and Fiol-Gerchkovitz-Komargodski. Comparing our results with the $\\mathcal{N}=4$ SYM ones, we obtain interpolating functions $f(g^2)$ such that a given $\\mathcal{N}=2$ SCFT observable is obtained by replacing in the corresponding $\\mathcal{N}=4$ SYM result the coupling constant by $f(g^2)$. These ``exact effective couplings'' encode the finite, relative renormalization between the $\\mathcal{N}=2$ and the $\\mathcal{N}=4$ gluon propagator, they interpolate between the weak and the strong coupling. We discuss the range of their applicability.

  8. Measurement of isomeric yield ratios in the photo-production of 133m,g;137m,gCe from natCe using 55-, 60-, and 65-MeV bremsstrahlung

    International Nuclear Information System (INIS)

    The isomeric yield ratios of 133m,gCe and 137m,gCe produced from the natCe(γ,xn) reactions were determined by using the activation and the off-line γ-ray spectrometric technique with the end-point bremsstrahlung energies of 55-, 60-, and 65-MeV at 100-MeV electron linac of the Pohang accelerator laboratory. The induced activities in the irradiated foils were measured by using an energy- and efficiency-calibrated HPGe detector coupled to a PC based multi-channel analyzer. The necessary corrections were made to improve the accuracy of the experimental results. The experimental results at bremsstrahlung energies of 55-, 60-, and 65-MeV were 0.324 ± 0.089, 0.331 ± 0.086, and 0.403 ± 0.089 for the 133m,gCe, and 0.210 ± 0.062, 0.221 ± 0.061, and 0.262 ± 0.061 for the 137m,gCe, respectively. The present results for natCe(γ,xn)133m,g;137m,gCe in this energy region were obtained for the first time which has no comparable literature data. The obtained isomeric yield ratios are compared with the calculated values based on the statistical model code TALYS 1.6

  9. Planetary Magnetism

    Science.gov (United States)

    Connerney, J. E. P.

    2007-01-01

    The chapter on Planetary Magnetism by Connerney describes the magnetic fields of the planets, from Mercury to Neptune, including the large satellites (Moon, Ganymede) that have or once had active dynamos. The chapter describes the spacecraft missions and observations that, along with select remote observations, form the basis of our knowledge of planetary magnetic fields. Connerney describes the methods of analysis used to characterize planetary magnetic fields, and the models used to represent the main field (due to dynamo action in the planet's interior) and/or remnant magnetic fields locked in the planet's crust, where appropriate. These observations provide valuable insights into dynamo generation of magnetic fields, the structure and composition of planetary interiors, and the evolution of planets.

  10. Quantum Magnetism

    CERN Document Server

    Barbara, Bernard; Sawatzky, G; Stamp, P. C. E

    2008-01-01

    This book is based on some of the lectures during the Pacific Institute of Theoretical Physics (PITP) summer school on "Quantum Magnetism", held during June 2006 in Les Houches, in the French Alps. The school was funded jointly by NATO, the CNRS, and PITP, and entirely organized by PITP. Magnetism is a somewhat peculiar research field. It clearly has a quantum-mechanical basis – the microsopic exchange interactions arise entirely from the exclusion principle, in conjunction with respulsive interactions between electrons. And yet until recently the vast majority of magnetism researchers and users of magnetic phenomena around the world paid no attention to these quantum-mechanical roots. Thus, eg., the huge ($400 billion per annum) industry which manufactures hard discs, and other components in the information technology sector, depends entirely on room-temperature properties of magnets - yet at the macroscopic or mesoscopic scales of interest to this industry, room-temperature magnets behave entirely classic...

  11. Magnet Systems

    Data.gov (United States)

    Federal Laboratory Consortium — Over the decades, Fermilab has been responsible for the design, construction, test and analysis of hundreds of conventional and superconducting accelerator magnets...

  12. MO-G-17A-06: Kernel Based Dosimetry for 90Y Microsphere Liver Therapy Using 90Y Bremsstrahlung SPECT/CT

    Energy Technology Data Exchange (ETDEWEB)

    Mikell, J; Siman, W; Kappadath, S [The University of Texas Graduate School of Biomedical Sciences at Houston, Houston, TX (United States); University of Texas MD Anderson Cancer Center, Houston, TX (United States); Mahvash, A [University of Texas MD Anderson Cancer Center, Houston, TX (United States); Mourtada, F [Christiana Care Hospital, Newark, DE (United States)

    2014-06-15

    Purpose: 90Y microsphere therapy in liver presents a situation where beta transport is dominant and the tissue is relatively homogenous. We compare voxel-based absorbed doses from a 90Y kernel to Monte Carlo (MC) using quantitative 90Y bremsstrahlung SPECT/CT as source distribution. Methods: Liver, normal liver, and tumors were delineated by an interventional radiologist using contrast-enhanced CT registered with 90Y SPECT/CT scans for 14 therapies. Right lung was segmented via region growing. The kernel was generated with 1.04 g/cc soft tissue for 4.8 mm voxel matching the SPECT. MC simulation materials included air, lung, soft tissue, and bone with varying densities. We report percent difference between kernel and MC (%Δ(K,MC)) for mean absorbed dose, D70, and V20Gy in total liver, normal liver, tumors, and right lung. We also report %Δ(K,MC) for heterogeneity metrics: coefficient of variation (COV) and D10/D90. The impact of spatial resolution (0, 10, 20 mm FWHM) and lung shunt fraction (LSF) (1,5,10,20%) on the accuracy of MC and kernel doses near the liver-lung interface was modeled in 1D. We report the distance from the interface where errors become <10% of unblurred MC as d10(side of interface, dose calculation, FWHM blurring, LSF). Results: The %Δ(K,MC) for mean, D70, and V20Gy in tumor and liver was <7% while right lung differences varied from 60–90%. The %Δ(K,MC) for COV was <4.8% for tumor and liver and <54% for the right lung. The %Δ(K,MC) for D10/D90 was <5% for 22/23 tumors. d10(liver,MC,10,1–20) awere <9mm and d10(liver,MC,20,1–20) awere <15mm; both agreed within 3mm to the kernel. d10(lung,MC,10,20), d10(lung,MC,10,1), d10(lung,MC,20,20), and d10(lung,MC,20,1) awere 6, 25, 15, and 34mm, respectively. Kernel calculations on blurred distributions in lung had errors > 10%. Conclusions: Liver and tumor voxel doses with 90Y kernel and MC agree within 7%. Large differences exist between the two methods in right lung. Research reported in this

  13. Magnetic Field

    DEFF Research Database (Denmark)

    Olsen, Nils

    2015-01-01

    he Earth has a large and complicated magnetic field, the major part of which is produced by a self-sustaining dynamo operating in the fluid outer core. Magnetic field observations provide one of the few tools for remote sensing the Earth’s deep interior, especially regarding the dynamics...... of the fluid flow at the top of the core. However, what is measured at or near the surface of the Earth is the superposition of the core field and fields caused by magnetized rocks in the Earth’s crust, by electric currents flowing in the ionosphere, magnetosphere, and oceans, and by currents induced...... in the Earth by time-varying external fields. These sources have their specific characteristics in terms of spatial and temporal variations, and their proper separation, based on magnetic measurements, is a major challenge. Such a separation is a prerequisite for remote sensing by means of magnetic field...

  14. Magnetic nanotubes

    Science.gov (United States)

    Matsui, Hiroshi; Matsunaga, Tadashi

    2010-11-16

    A magnetic nanotube includes bacterial magnetic nanocrystals contacted onto a nanotube which absorbs the nanocrystals. The nanocrystals are contacted on at least one surface of the nanotube. A method of fabricating a magnetic nanotube includes synthesizing the bacterial magnetic nanocrystals, which have an outer layer of proteins. A nanotube provided is capable of absorbing the nanocrystals and contacting the nanotube with the nanocrystals. The nanotube is preferably a peptide bolaamphiphile. A nanotube solution and a nanocrystal solution including a buffer and a concentration of nanocrystals are mixed. The concentration of nanocrystals is optimized, resulting in a nanocrystal to nanotube ratio for which bacterial magnetic nanocrystals are immobilized on at least one surface of the nanotubes. The ratio controls whether the nanocrystals bind only to the interior or to the exterior surfaces of the nanotubes. Uses include cell manipulation and separation, biological assay, enzyme recovery, and biosensors.

  15. Compression and Cavitation of Externally Applied Magnetic Field on a Hohlraum due to Non-Local Heat Flow Effects

    Science.gov (United States)

    Joglekar, Archis; Thomas, Alec; Ridgers, Chris; Kingham, Rob

    2015-11-01

    In this study, we present full-scale 2D kinetic modeling of externally imposed magnetic fields on hohlraums with laser heating. We observe magnetic field cavitation and compression due to thermal energy transport. Self-consistent modeling of the electron momentum equation allows for a complete treatment of the heat flow equation and Ohm's Law. A complete Ohm's Law contains magnetic field advection through the Nernst mechanism that arises due to the heat flow. Magnetic field amplification by a factor of 3 occurs due to magnetic flux pile-up from Nernst convection. The magnetic field cavitates towards the hohlraum axis over a 0.5 ns time scale due to Nernst convection. This results in significantly different magnetic field profiles and slower cavitation than can be expected due to the plasma bulk flow. Non-local electrons contribute to the heat flow down the density gradient resulting in an augmented Nernst convection mechanism that is included self-consistently through kinetic modeling. In addition to showing the prevalence of non-local heat flows, we show effects such as anomalous heat flow up the density gradient induced by inverse bremsstrahlung heating. This research was supported by the DOE through Grant No. DE SC0010621 and in part through computational resources and services provided by Advanced Research Computing at the University of Michigan, Ann Arbor.

  16. Electron Acceleration by Cascading Reconnection in the Solar Corona. I. Magnetic Gradient and Curvature Drift Effects

    Science.gov (United States)

    Zhou, X.; Büchner, J.; Bárta, M.; Gan, W.; Liu, S.

    2015-12-01

    We investigate the electron acceleration by magnetic gradient and curvature drift effects in cascading magnetic reconnection of a coronal current sheet via a test particle method in the framework of the guiding center approximation. After several Alfvén transit times, most of the electrons injected at the current sheet are still trapped in the magnetic islands. A small fraction of the injected electrons precipitate into the chromosphere. The acceleration of trapped electrons is dominated by the magnetic curvature drifts, which change the parallel momentum of the electron, and appears to be more efficient than the acceleration of precipitating electrons, which is dominated by the perpendicular momentum change caused by the magnetic gradient drifts. With the resulting trapped energetic electron distribution, the corresponding hard X-ray (HXR) radiation spectra are calculated using an optically thin Bremsstrahlung model. Trapped electrons may explain flare loop top HXR emission as well as the observed bright spots along current sheets trailing coronal mass ejections. The asymmetry of precipitating electrons with respect to the polarity inversion line may contribute to the observed asymmetry of footpoint emission.

  17. ELECTRON ACCELERATION BY CASCADING RECONNECTION IN THE SOLAR CORONA. I. MAGNETIC GRADIENT AND CURVATURE DRIFT EFFECTS

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, X.; Büchner, J.; Bárta, M. [Max Planck Institute for Solar System Research, Justus-von-Liebig-Weg 3, D-37077 Göttingen (Germany); Gan, W.; Liu, S. [Key Laboratory of Dark Matter and Space Astronomy, Purple Mountain Observatory, Chinese Academy of Sciences, Nanjing, 210008 (China)

    2015-12-10

    We investigate the electron acceleration by magnetic gradient and curvature drift effects in cascading magnetic reconnection of a coronal current sheet via a test particle method in the framework of the guiding center approximation. After several Alfvén transit times, most of the electrons injected at the current sheet are still trapped in the magnetic islands. A small fraction of the injected electrons precipitate into the chromosphere. The acceleration of trapped electrons is dominated by the magnetic curvature drifts, which change the parallel momentum of the electron, and appears to be more efficient than the acceleration of precipitating electrons, which is dominated by the perpendicular momentum change caused by the magnetic gradient drifts. With the resulting trapped energetic electron distribution, the corresponding hard X-ray (HXR) radiation spectra are calculated using an optically thin Bremsstrahlung model. Trapped electrons may explain flare loop top HXR emission as well as the observed bright spots along current sheets trailing coronal mass ejections. The asymmetry of precipitating electrons with respect to the polarity inversion line may contribute to the observed asymmetry of footpoint emission.

  18. Giant dipole resonance decay and bremsstrahlung emission as a source of high-energy gamma-rays in sup 1 sup 2 C+ sup 2 sup 4 sup , sup 2 sup 6 Mg and sup 1 sup 2 C+ sup 5 sup 8 sup , sup 6 sup 4 Ni reactions at 6-11 MeV/u

    CERN Document Server

    Kicinska-Habior, M; Maj, A; Kelly, M P; Schagen, J P S; Snover, K A

    1999-01-01

    It is shown that in the mass-asymmetric reactions, sup 1 sup 2 C+ sup 2 sup 4 sup , sup 2 sup 6 Mg and sup 1 sup 2 C+ sup 5 sup 8 sup , sup 6 sup 4 Ni, at E sub p /A = 6-11 MeV/u, the two types of gamma-ray emission, statistical GDR decay and bremsstrahlung radiation, may be disentangled using angular distribution measurements. The analyzed data give information on the GDR built on excited states as well as on the bremsstrahlung process. The extracted GDR parameters and bremsstrahlung parameters for sup 1 sup 2 C+ sup 2 sup 4 sup , sup 2 sup 6 Mg are in general in agreement with the systematics. However, the inverse slope parameter, E sub 0 , depends on gamma-ray energy and as a result the bremsstrahlung cross-section at low and high E subgamma energies is lower than expected for constant E sub 0 value.

  19. General Relativistic Magnetohydrodynamic Simulations of the Hard State as a Magnetically-Dominated Accretion Flow

    CERN Document Server

    Fragile, P Chris

    2008-01-01

    (Abridged) We present one of the first physically-motivated two-dimensional general relativistic magnetohydrodynamic (GRMHD) numerical simulations of a radiatively-cooled black-hole accretion disk. The fiducial simulation combines a total-energy-conserving formulation with a radiative cooling function, which includes bremsstrahlung, synchrotron, and Compton effects. By comparison with other simulations we show that in optically thin advection-dominated accretion flows, radiative cooling can significantly affect the structure, without necessarily leading to an optically thick, geometrically thin accretion disk. We further compare the results of our radiatively-cooled simulation to the predictions of a previously developed analytic model for such flows. For the very low stress parameter and accretion rate found in our simulated disk, we closely match a state called the "transition" solution between an outer advection-dominated accretion flow and what would be a magnetically-dominated accretion flow (MDAF) in th...

  20. Lunar magnetism

    Science.gov (United States)

    Hood, L. L.; Sonett, C. P.; Srnka, L. J.

    1984-01-01

    Aspects of lunar paleomagnetic and electromagnetic sounding results which appear inconsistent with the hypothesis that an ancient core dynamo was the dominant source of the observed crustal magnetism are discussed. Evidence is summarized involving a correlation between observed magnetic anomalies and ejecta blankets from impact events which indicates the possible importance of local mechanisms involving meteoroid impact processes in generating strong magnetic fields at the lunar surface. A reply is given to the latter argument which also presents recent evidence of a lunar iron core.

  1. Measurement of isomeric ratios for {sup 89g,m}Zr, {sup 91g,m}Mo, and {sup 97g,m}Nb in the bremsstrahlung end-point energies of 16 and 45-70 MeV

    Energy Technology Data Exchange (ETDEWEB)

    Naik, H.; Goswami, A. [Radiochemistry Division, Bhabha Atomic Research Centre, Mumbai (India); Kim, G.N.; Kim, K.; Zaman, M. [Kyungpook National University, Department of Physics, Daegu (Korea, Republic of); Schwengner, R.; Massarczyk, R.; John, R.; Junghans, A.; Wagner, A. [Institute of Radiation Physics, Dresden (Germany); Yang, S.C. [Kyungpook National University, Department of Physics, Daegu (Korea, Republic of); Korea Atomic Energy Research Institute, Nuclear Data Center, Dajeon (Korea, Republic of); Shin, S.G.; Kye, Y.U.; Cho, M.H. [Pohang University of Science and Technology, Division of Advanced Nuclear Engineering, Pohang (Korea, Republic of)

    2016-03-15

    The independent isomeric yield ratios of {sup 89g,m}Zr from the {sup nat}Zr(γ,xn) reactions and those of {sup 91g,} {sup m}Mo and {sup 97g,m}Nb from the {sup nat}Mo(γ,x) reactions with the bremsstrahlung end-point energy of 45-70 MeV were determined by an off-line γ -ray spectrometric technique using the 100 MeV electron linac at the Pohang Accelerator Laboratory, Korea. The isomeric yield ratios of {sup 89g,m}Zr and {sup 97g,m}Nb from the {sup nat}Zr(γ, xn) and {sup nat}Mo(γ,x) reactions at the bremsstrahlung end-point energy of 16MeV were also determined by the same technique using the 20MeV electron linac at Helmholtz-Zentrum Dresden-Rossendorf, Germany. The measured isomeric yield ratios of {sup 89g,m}Zr, {sup 91g,m}Mo, and {sup 97g,m}Nb were compared with literature data to examine the role of the Giant Dipole Resonance (GDR). The isomeric yield ratios of the {sup 89g,m}Zr, {sup 91g,m}Mo, and {sup 97g,m}Nb from the above reactions were also calculated by using the computer code TALYS 1.6 and compared with the experimental data to examine the validity of the theoretical model for independent isomeric yield ratio calculations. (orig.)

  2. Quantum magnetism

    CERN Document Server

    Richter, Johannes; Farnell, Damian; Bishop, Raymod

    2004-01-01

    The investigation of magnetic systems where quantum effects play a dominant role has become a very active branch of solid-state-physics research in its own right. The first three chapters of the "Quantum Magnetism" survey conceptual problems and provide insights into the classes of systems considered, namely one-dimensional, two-dimensional and molecular magnets. The following chapters introduce the methods used in the field of quantum magnetism, including spin wave analysis, exact diagonalization, quantum field theory, coupled cluster methods and the Bethe ansatz. The book closes with a chapter on quantum phase transitions and a contribution that puts the wealth of phenomena into the context of experimental solid-state physics. Closing a gap in the literature, this volume is intended both as an introductory text at postgraduate level and as a modern, comprehensive reference for researchers in the field.

  3. Magnetic monopoles

    International Nuclear Information System (INIS)

    In this talk on magnetic monopoles, first the author briefly reviews some historical background; then, the author describes what several different types of monopoles might look like; and finally the author discusses the experimental situation. 81 references

  4. Magnetic monopoles

    Energy Technology Data Exchange (ETDEWEB)

    Fryberger, D.

    1984-12-01

    In this talk on magnetic monopoles, first the author briefly reviews some historical background; then, the author describes what several different types of monopoles might look like; and finally the author discusses the experimental situation. 81 references.

  5. Magnetism. Blowing magnetic skyrmion bubbles.

    Science.gov (United States)

    Jiang, Wanjun; Upadhyaya, Pramey; Zhang, Wei; Yu, Guoqiang; Jungfleisch, M Benjamin; Fradin, Frank Y; Pearson, John E; Tserkovnyak, Yaroslav; Wang, Kang L; Heinonen, Olle; te Velthuis, Suzanne G E; Hoffmann, Axel

    2015-07-17

    The formation of soap bubbles from thin films is accompanied by topological transitions. Here we show how a magnetic topological structure, a skyrmion bubble, can be generated in a solid-state system in a similar manner. Using an inhomogeneous in-plane current in a system with broken inversion symmetry, we experimentally "blow" magnetic skyrmion bubbles from a geometrical constriction. The presence of a spatially divergent spin-orbit torque gives rise to instabilities of the magnetic domain structures that are reminiscent of Rayleigh-Plateau instabilities in fluid flows. We determine a phase diagram for skyrmion formation and reveal the efficient manipulation of these dynamically created skyrmions, including depinning and motion. The demonstrated current-driven transformation from stripe domains to magnetic skyrmion bubbles could lead to progress in skyrmion-based spintronics. PMID:26067256

  6. THERMAL EQUILIBRIA OF OPTICALLY THIN, MAGNETICALLY SUPPORTED, TWO-TEMPERATURE, BLACK HOLE ACCRETION DISKS

    International Nuclear Information System (INIS)

    We obtained thermal equilibrium solutions for optically thin, two-temperature black hole accretion disks incorporating magnetic fields. The main objective of this study is to explain the bright/hard state observed during the bright/slow transition of galactic black hole candidates. We assume that the energy transfer from ions to electrons occurs via Coulomb collisions. Bremsstrahlung, synchrotron, and inverse Compton scattering are considered as the radiative cooling processes. In order to complete the set of basic equations, we specify the magnetic flux advection rate instead of β = pgas/pmag. We find magnetically supported (low-β), thermally stable solutions. In these solutions, the total amount of the heating via the dissipation of turbulent magnetic fields goes into electrons and balances the radiative cooling. The low-β solutions extend to high mass accretion rates (∼>α2M-dotEdd) and the electron temperature is moderately cool (Te ∼ 108-109.5 K). High luminosities (∼>0.1LEdd) and moderately high energy cutoffs in the X-ray spectrum (∼50-200 keV) observed in the bright/hard state can be explained by the low-β solutions.

  7. Magnetic monopoles and dipoles

    CERN Multimedia

    Dominguez, Daniel

    2016-01-01

    Conventional bar magnets are also called ‘magnetic dipoles’ because they have two magnetic poles (a “North” and a “South” magnetic pole, like the Earth). In theory, “magnetic monopoles” could exist that act like an isolated “magnetic charge”, i.e. either a “North” or a “South” magnetic pole.

  8. Magnetism Materials and Applications

    CERN Document Server

    Trémolet de Lacheisserie, Étienne; Schlenker, Michel

    2005-01-01

    This book treats permanent magnet (hard) materials, magnetically soft materials for low-frequency applications and for high-frequency electronics, magnetostrictive materials, superconductors, magnetic-thin films and multilayers, and ferrofluids. Chapters are dedicated to magnetic recording, the role of magnetism in magnetic resonance imaging (MRI), and instrumentation for magnetic measurements.   

  9. Designing a magnet for magnetic refrigeration

    Energy Technology Data Exchange (ETDEWEB)

    Bjoerk, R.

    2010-03-15

    This thesis investigates the design and optimization of a permanent magnet assembly for use in a magnetic refrigeration device. The heart of magnetic refrigeration is the adiabatic temperature change in the magnetocaloric material which is caused by the magnetic field. In order to design an ideal magnet assembly the magnetocaloric materials and the refrigeration process itself and their properties and performance as a function of magnetic field are investigated. For the magnetocaloric materials it is the magnetization, specific heat capacity and adiabatic temperature that are investigated as functions of the magnetic field. Following this the process utilized by a magnetic refrigerator to provide cooling is investigated using a publicly available one dimensional numerical model. This process is called active magnetic regeneration (AMR). The aim is to determine the performance of the AMR as a function of the magnetic field in order to learn the properties of the optimal magnet assembly. The performance of the AMR as a function of the synchronization and width of the magnetic field with respect to the AMR cycle, the ramp rate and maximum value of the magnetic field are investigated. Other published magnet designs used in magnetic refrigeration devices are also evaluated, using a figure of merit based on the properties of the investigated magnetocaloric materials, to learn the properties of the best magnet designs to date. Following this investigation the Halbach cylinder, which is a hollow permanent magnet cylinder with a rotating remanent flux density, is investigated in detail as it forms the basis of many magnet designs used in magnetic refrigeration. Here the optimal dimensions of a Halbach cylinder, as well as analytical calculations of the magnetic field for a Halbach cylinder of infinite length, are presented. Once it has been determined which properties are desirable for a magnet used in magnetic refrigeration the design of a new magnet is described. This is

  10. USE OF SUPERCONDUCTING MAGNETS IN MAGNETIC SEPARATION

    OpenAIRE

    Parker, M.

    1984-01-01

    A review is given assessing the potential for superconducting high-field magnet systems in magnetic separation. Particular attention is given to the advantages of the reciprocating canister approach to high gradient magnetic separation and to the use of quadrupole magnets in open gradient magnetic separation.

  11. Magnetic guns with cylindrical permanent magnets

    DEFF Research Database (Denmark)

    Vokoun, David; Beleggia, Marco; Heller, Luděk

    2012-01-01

    The motion of a cylindrical permanent magnet (projectile) inside a tubular permanent magnet, with both magnets magnetized axially, illustrates nicely the physical principles behind the operation of magnetic guns. The force acting upon the projectile is expressed semi-analytically as derivative...

  12. Random magnetism

    International Nuclear Information System (INIS)

    The 'ingredients' which control a phase transition in well defined systems as well as in random ones (e.q. random magnetic systems) are listed and discussed within a somehow unifying perspective. Among these 'ingredients' the couplings and elements responsible for the cooperative phenomenon, the topological connectivity as well as possible topological incompatibilities, the influence of new degrees of freedom, the order parameter dimensionality, the ground state degeneracy and finally the 'quanticity' of the system are found. The general trends, though illustrated in magnetic systems, essentially hold for all phase transitions, and give a basis for connection of this area with Field theory, Theory of dynamical systems, etc. (Author)

  13. Magnetic Catalysis vs Magnetic Inhibition

    CERN Document Server

    Fukushima, Kenji

    2012-01-01

    We discuss the fate of chiral symmetry in an extremely strong magnetic field B. We investigate not only quark fluctuations but also neutral meson effects. The former would enhance the chiral-symmetry breaking at finite B according to the Magnetic Catalysis, while the latter would suppress the chiral condensate once B exceeds the scale of the hadron structure. Using a chiral model we demonstrate how neutral mesons are subject to the dimensional reduction and the low dimensionality favors the chiral-symmetric phase. We point out that this effect, the Magnetic Inhibition, can be a feasible explanation for recent lattice-QCD data indicating the decreasing behavior of the chiral-restoration temperature with increasing B.

  14. Permanent magnet array for the magnetic refrigerator

    Science.gov (United States)

    Lee, S. J.; Kenkel, J. M.; Pecharsky, V. K.; Jiles, D. C.

    2002-05-01

    Recent research into the development of magnetic refrigeration (MR) operating at room temperature has shown that it can provide a reliable, energy-efficient cooling system. To enhance the cooling power of the magnetic refrigerator, it is required to use a magnetic refrigerant material with large magnetocaloric effect (MCE) at the appropriate temperature. Most advanced magnetic refrigerant materials show largest MCE at high applied magnetic fields generated by a superconducting magnet. For application of MCE to air conditioners or household refrigerators, it is essential to develop a permanent magnet array to form a compact, strong, and energy-efficient magnetic field generator. Generating a magnetic field well above the remanence of a permanent magnet material is hard to achieve through conventional designs. A permanent magnet array based on a hollow cylindrical flux source is found to provide an appropriate geometry and magnetic field strength for MR applications.

  15. Magnetic Design of Superconducting Magnets

    CERN Document Server

    Todesco, E

    2014-01-01

    In this paper we discuss the main principles of magnetic design for superconducting magnets (dipoles and quadrupoles) for particle accelerators. We give approximated equations that govern the relation between the field/gradient, the current density, the type of superconductor (Nb−Ti or Nb3Sn), the thickness of the coil, and the fraction of stabilizer. We also state the main principle controlling the field quality optimization, and discuss the role of iron. A few examples are given to show the application of the equations and their validity limits.

  16. Magnetic Fluids: Biomedical Applications and Magnetic Fractionation

    OpenAIRE

    Rheinländer, Thomas; Kötitz, Róman; Weitschies, Werner; Semmler, Wolfhard

    2000-01-01

    In addition to engineering applications, magnetic fluids containing magnetic nanoparticles are being increasingly applied to biomedical purposes. Besides the well established use of magnetic particles for biological separation or as contrast agents for magnetic resonance imaging, magnetic particles are also being tested for the inductive heat treatment of tumors or as markers for the quantification of biologically active substances. The properties of magnetic nanoparticles usually exhibit a b...

  17. Neutron Scattering studies of magnetic molecular magnets

    International Nuclear Information System (INIS)

    This work deals with inelastic neutron scattering studies of magnetic molecular magnets and focuses on their magnetic properties at low temperature and low energies. Several molecular magnets (Mn12, V15, Ni12, Mn4, etc.) are reviewed. Inelastic neutron scattering is shown to be a perfectly suited spectroscopy tool to -a) probe magnetic energy levels in such systems and -b) provide key information to understand the quantum tunnel effect of the magnetization in molecular spin clusters. (author)

  18. Studies of an extractor geometry magnetically insulated ion diode with an exploding metal film anode plasma

    International Nuclear Information System (INIS)

    Magnetically insulated diodes (MIDs) are of interest as ion sources for inertial confinement fusion. The authors examined several issues that are of concern with MIDs, including ion turn-on delay and anode plasma production, and diode impedance history and particle current scaling with the applied magnetic field and gas spacing. The LION pulsed power generator (1.5 MV, 4 Ω, 40 ns pulse length) was used to power an extractor geometry magnetically insulated (radical magnetic field) ion beam diode. The diode was studied with three anode configurations. In the first, with epoxy-filled-groove (epoxy) anodes, scaling of the ion and electron currents with the gap and the magnetic field was examined. He found that the observed ion current is consistent with a diode model that has been successful with barrel geometry MIDs. The electron leakage current scaled proportionally to 1/Bd2, where d is the anode-cathode gap spacing and B is the magnetic field strength. Studies of ion beam propagation in vacuum showed that space charge non-neutrality near the magnetic field coils caused the beam to expand initially. Later in the ion pulse (20 to 30 ns), the beam expansion became much less severe. The second anode configuration utilized an electron collector protruding above an epoxy anode surface. With the collector, he observed less bremsstrahlung across the active anode region. The last anode configuration studied was the exploding metal film active anode plasma source (EMFAAPS). Current from the accelerator was directed by an electron collector or a plasma opening switch through a thin aluminum film, which exploded to form the anode plasma

  19. Designing a magnet for magnetic refrigeration

    DEFF Research Database (Denmark)

    Bjørk, Rasmus

    permanent magnet cylinder with a rotating remanent flux density, is investigated in detail as it forms the basis of many magnet designs used in magnetic refrigeration. Here the optimal dimensions of a Halbach cylinder, as well as analytical calculations of the magnetic field for a Halbach cylinder...... design must have alternating regions of high and low magnetic field. As a basis for the magnet design the concentric Halbach cylinder design is chosen. This design is then optimized by employing several developed optimization schemes that lower the flux density in a specific region and lower the amount...... of magnet material used in a given magnet assembly. These schemes are applied to a numerical model of the magnet design. Afterwards the magnet design is dimensioned and segmented to allow construction. This design has been constructed and the flux density measured. Finally, the magnetic forces internally...

  20. Tuning the Magnetic Transport of an Induction LINAC using Emittance

    Energy Technology Data Exchange (ETDEWEB)

    Houck, T L; Brown, C G; Ong, M M; Paul, A C; Wargo, P E; Zentler, J M

    2006-08-11

    The Lawrence Livermore National Laboratory Flash X-Ray (FXR) machine is a linear induction accelerator used to produce a nominal 18 MeV, 3 kA, 65 ns pulse width electron beam for hydrodynamic radiographs. A common figure of merit for this type of radiographic machine is the x-ray dose divided by the spot area on the bremsstrahlung converter where a higher FOM is desired. Several characteristics of the beam affect the minimum attainable x-ray spot size. The most significant are emittance (chaotic transverse energy), chromatic aberration (energy variation), and beam motion (transverse instabilities and corkscrew motion). FXR is in the midst of a multi-year optimization project to reduce the spot size. This paper describes the effort to reduce beam emittance by adjusting the fields of the transport solenoids and position of the cathode. If the magnetic transport is not correct, the beam will be mismatched and undergo envelope oscillations increasing the emittance. We measure the divergence and radius of the beam in a drift section after the accelerator by imaging the optical transition radiation (OTR) and beam envelope on a foil. These measurements are used to determine an emittance. Relative changes in the emittance can be quickly estimated from the foil measurements allowing for an efficient, real-time study. Once an optimized transport field is determined, the final focus can be adjusted and the new x-ray spot measured. A description of the diagnostics and analysis is presented.

  1. magnetic horn

    CERN Multimedia

    Neutrinos and antineutrinos are ideal for probing the weak force because it is effectively the only force they feel. How were they made? Protons fired into a metal target produce a tangle of secondary particles. A magnetic horn like this one, invented by Simon Van der Meer, selected pions and focused them into a sharp beam. Pions decay into muons and neutrinos or antineutrinos. The muons were stopped in a wall of 3000 tons of iron and 1000 tons of concrete, leaving the neutrinos or antineutrinos to reach the Gargamelle bubble chamber. A simple change of magnetic field direction on the horn flipped between focusing positively- or negatively-charged pion beams, and so between neutrinos and antineutrinos.

  2. Planetary magnetism

    International Nuclear Information System (INIS)

    Experimental data on magnetic fields of planets are surveyed. The magnetic fields of the Earth, Jupiter, Mars, Mercury, Venus, and the Moon are considered in detail. A similarity of the physical models of both the planets of the Earth group and the giant planets was revealed. The fields of the planets and of the Earth are compared in the scheme of the precession dynamo and in the kinematic scheme. Proceeding from the assumption that the Poincare forces and their ratio to other forces are model-similar in the cores of all the planets, the values of Hsub(i)/Hsub(E) are calculated, where Hsub(i) and Hsub(E) are the field strengths of the i-th planet and that of the Earth. The experimental data on the dynamic compression of the Mercury confirm the calculations made. It is concluded that the problem of the origin and moving forces of the terrestrial magnetic field may be resolved only within the framework of comparative planetology

  3. MAGNET / INFRASTRUCTURE

    CERN Multimedia

    D. Campi

    The final fast discharge of the Magnet took place on 3rd of November. The Coil reached a temperature of 70K by internal energy dissipation. By injecting a current of 200 A room temperature was reached on the 23rd November. During the heating of the coil un-connecting of the first magnet connectors on YBO was started to give the earliest possible access to the assembly groups and to continue the installation of the muon chambers. The removal of the pumping lines and the disconnection of the vacuum system was instead done as soon as the room temperature was reached: more precisely from the 4 to the 18 December. The disconnection of the transfer line from the cold box and the completion of the removal of the control cables of the vacuum system and cryogenics was done at last. In January 2007 the disconnection of MCS-MSS, CDS, vacuum racks and their cable trays was also achieved. After coil disconnection the effort of the magnet team has been mainly devoted in optimizing the lowering and reassembly of the a...

  4. Magnetic Reconnection

    Energy Technology Data Exchange (ETDEWEB)

    Masaaki Yamada, Russell Kulsrud and Hantao Ji

    2009-09-17

    We review the fundamental physics of magnetic reconnection in laboratory and space plasmas, by discussing results from theory, numerical simulations, observations from space satellites, and the recent results from laboratory plasma experiments. After a brief review of the well-known early work, we discuss representative recent experimental and theoretical work and attempt to interpret the essence of significant modern findings. In the area of local reconnection physics, many significant findings have been made with regard to two- uid physics and are related to the cause of fast reconnection. Profiles of the neutral sheet, Hall currents, and the effects of guide field, collisions, and micro-turbulence are discussed to understand the fundamental processes in a local reconnection layer both in space and laboratory plasmas. While the understanding of the global reconnection dynamics is less developed, notable findings have been made on this issue through detailed documentation of magnetic self-organization phenomena in fusion plasmas. Application of magnetic reconnection physics to astrophysical plasmas is also brie y discussed.

  5. Magnetic semiconductors

    Energy Technology Data Exchange (ETDEWEB)

    Bihler, Christoph

    2009-04-15

    In this thesis we investigated in detail the properties of Ga{sub 1-x}Mn{sub x}As, Ga{sub 1-x}Mn{sub x}P, and Ga{sub 1-x}Mn{sub x}N dilute magnetic semiconductor thin films with a focus on the magnetic anisotropy and the changes of their properties upon hydrogenation. We applied two complementary spectroscopic techniques to address the position of H in magnetic semiconductors: (i) Electron paramagnetic resonance, which provides direct information on the symmetry of the crystal field of the Mn{sup 2+} atoms and (ii) x-ray absorption fine structure analysis which allows to probe the local crystallographic neighborhood of the absorbing Mn atom via analysing the fine structure at the Mn K absorption edge. Finally, we discussed the obstacles that have to be overcome to achieve Curie temperatures above the current maximum in Ga{sub 1-x}Mn{sub x}As of 185 K. Here, we outlined in detail the generic problem of the formation of precipitates at the example of Ge:MN. (orig.)

  6. MHD simulations of magnetized laser-plasma interaction for laboratory astrophysics

    Science.gov (United States)

    Khiar, Benjamin; Ciardi, Andrea; Vinci, Tommaso; Revet, Guilhem; Fuchs, Julien; Higginson, Drew

    2015-11-01

    Laser-driven plasmas coupled with externally applied strong, steady-state, magnetic fields have applications that range from ICF to astrophysical studies of jet collimation, accretion shock dynamics in young stars and streaming instabilities in space plasmas. We have recently included the modelling of laser energy deposition in our three-dimensional, resistive two-temperature MHD code GORGON. The model assumes linear inverse-bremsstrahlung absorption and the laser propagation is done in the geometrical optics approximation. We present full scale numerical simulations of actual experiments performed on the ELFIE installation at LULI, including plasma generated from single and multiple laser plasmas embedded in a magnetic field of strength up to 20 T, and experiments and astrophysical simulations that have shown the viability of poloidal magnetic fields to directly result in the collimation of outflows and the formation of jets in astrophysical accreting systems, such as in young stellar objects. The authors acknowledge the support from the Ile-de-France DIM ACAV, from the LABEX Plas@par and from the ANR grant SILAMPA.

  7. An optimized magnet for magnetic refrigeration

    OpenAIRE

    Bjørk, Rasmus; Bahl, Christian Robert Haffenden; Smith, Anders; Christensen, Dennis; Pryds, Nini

    2014-01-01

    A magnet designed for use in a magnetic refrigeration device is presented. The magnet is designed by applying two general schemes for improving a magnet design to a concentric Halbach cylinder magnet design and dimensioning and segmenting this design in an optimum way followed by the construction of the actual magnet. The final design generates a peak value of 1.24 T, an average flux density of 0.9 T in a volume of 2 L using only 7.3 L of magnet, and has an average low flux density of 0.08 T ...

  8. Properties of carbon-based structures synthesized in nuclear reactions induced by bremsstrahlung γ quanta with threshold energy of 10 MeV at helium pressure of 1.1 kbar

    Science.gov (United States)

    Didyk, A. Yu.; Wiśniewski, R.

    2016-07-01

    Helium gas with an initial pressure of about 1.1 kbar inside a high-pressure chamber (HeHPC) has been irradiated by bremsstrahlung γ quanta with a threshold energy of 10 MeV for 1.0 × 105 s produced by an electron-beam current of 22-24 μA. After opening the HeHPC, the residual pressure of helium is equal to 430 bar. Synthesized black foils with a variety of other objects are found inside the HeHPC. They are located on the inner surfaces of the reaction chamber made of high-purity copper (99.99%), the entrance the window of γ quanta made of beryllium bronze and a copper container of nuclear and chemical reaction products. Elemental analysis with the use of scanning electron microscopy and X-ray microprobe analysis has revealed that the foils contain predominantly carbon and small quantities of other elements from carbon to iron. The results are in good agreement with the cycle of investigations of the authors devoted to the γ-quanta irradiation of dense hydrogen and helium gases in the presence (absence) of metals in a reaction chamber.

  9. Damage diagnosis for bremsstrahlung converter target of Dragon-I linear induction accelerator%神龙一号直线感应加速器X光转换靶破坏诊断

    Institute of Scientific and Technical Information of China (English)

    禹海军; 朱隽; 江孝国; 王远; 陈楠; 张振涛; 戴文华; 刘承俊

    2011-01-01

    The electron beam generated by the Dragon- I linear induction accelerator strikes the bremsstrahlung converter target to generate X-ray and causes tantalum target damage and hydrodynamic expansion, which results in target density decreasing for successive pulses.The time varying target density was measured by applying a low energy X-ray with energy about 450 kev and spot diameter of 1 to 4 mm along with an intensified charge coupled derice(ICCD) camera.The experiment results show that the target density is basically unchanged for 1 μs after beam-target interaction, and no particle ejected from the front side of the target is found at the same time.%利用能量约450 keV、焦斑直径1~4 mm的低能X光对神龙一号直线感应加速器束靶作用后钽靶的破坏进行诊断,利用增强型电荷耦合器件(ICCD)对诊断过程记录,得到束靶作用后数μs时间内钽靶材料密度的变化.结果表明:在束靶作用后约1μs内靶材料密度基本没有变化,且该时间段内ICCD相机没有观察到有靶前钽靶材料的微粒喷射.

  10. Physics of magnetism and magnetic materials

    CERN Document Server

    Buschow, K H J

    2003-01-01

    In this book, the fundamentals of magnetism are treated, starting at an introductory level. The origin of magnetic moments, the response to an applied magnetic field, and the various interactions giving rise to different types of magnetic ordering in solids are presented and many examples are given. Crystalline-electric-field effects are treated at a level that is sufficient to provide the basic knowledge necessary in understanding the properties of materials in which these effects play a role. Itinerant-electron magnetism is presented on a similar basis. Particular attention has been given to magnetocrystalline magnetic anisotropy and the magnetocaloric effect. Also, the usual techniques for magnetic measurements are presented. About half of the book is devoted to magnetic materials and the properties that make them suitable for numerous applications. The state of the art is presented of permanent magnets, high-density recording materials, soft-magnetic materials, Invar alloys and magnetostrictive materials....

  11. Associated Particle Tagging (APT) in Magnetic Spectrometers

    Energy Technology Data Exchange (ETDEWEB)

    Jordan, David V.; Baciak, James E.; Stave, Sean C.; Chichester, David; Dale, Daniel; Kim, Yujong; Harmon, Frank

    2012-10-16

    Summary In Brief The Associated Particle Tagging (APT) project, a collaboration of Pacific Northwest National Laboratory (PNNL), Idaho National Laboratory (INL) and the Idaho State University (ISU)/Idaho Accelerator Center (IAC), has completed an exploratory study to assess the role of magnetic spectrometers as the linchpin technology in next-generation tagged-neutron and tagged-photon active interrogation (AI). The computational study considered two principle concepts: (1) the application of a solenoidal alpha-particle spectrometer to a next-generation, large-emittance neutron generator for use in the associated particle imaging technique, and (2) the application of tagged photon beams to the detection of fissile material via active interrogation. In both cases, a magnetic spectrometer momentum-analyzes charged particles (in the neutron case, alpha particles accompanying neutron generation in the D-T reaction; in the tagged photon case, post-bremsstrahlung electrons) to define kinematic properties of the relevant neutral interrogation probe particle (i.e. neutron or photon). The main conclusions of the study can be briefly summarized as follows: Neutron generator: • For the solenoidal spectrometer concept, magnetic field strengths of order 1 Tesla or greater are required to keep the transverse size of the spectrometer smaller than 1 meter. The notional magnetic spectrometer design evaluated in this feasibility study uses a 5-T magnetic field and a borehole radius of 18 cm. • The design shows a potential for 4.5 Sr tagged neutron solid angle, a factor of 4.5 larger than achievable with current API neutron-generator designs. • The potential angular resolution for such a tagged neutron beam can be less than 0.5o for modest Si-detector position resolution (3 mm). Further improvement in angular resolution can be made by using Si-detectors with better position resolution. • The report documents several features of a notional generator design incorporating the

  12. Magnetic helicity and cosmological magnetic field

    OpenAIRE

    Semikoz, V. B.; Sokoloff, D. D.

    2004-01-01

    The magnetic helicity has paramount significance in nonlinear saturation of galactic dynamo. We argue that the magnetic helicity conservation is violated at the lepton stage in the evolution of early Universe. As a result, a cosmological magnetic field which can be a seed for the galactic dynamo obtains from the beginning a substantial magnetic helicity which has to be taken into account in the magnetic helicity balance at the later stage of galactic dynamo.

  13. Magnetic fluids - suspensions of magnetic dipoles and their magnetic control

    CERN Document Server

    Odenbach, S

    2003-01-01

    Suspensions of magnetic nanoparticles exhibit normal liquid behaviour coupled with superparamagnetic properties. This leads to the possibility to control the properties and the flow of these liquids with moderate magnetic fields. The magnetic control enables various experiments in fluid mechanics and gives rise to the development of numerous technical and medical applications. Ferrofluids and their general properties will be introduced and, as examples for the magnetic control of their flow and properties, thermomagnetic convection and magnetoviscous effects will be discussed in some detail.

  14. Magnetic balltracking: Tracking the photospheric magnetic flux

    CERN Document Server

    Attie, R

    2014-01-01

    Context: One aspect of understanding the dynamics of the quiet Sun is to quantify the evolution of the flux within small-scale magnetic features. These features are routinely observed in the quiet photosphere and were given various names, such as pores, knots, magnetic patches. Aims: This work presents a new algorithm for tracking the evolution of the broad variety of small-scale magnetic features in the photosphere, with a precision equal to the instrumental resolution. Methods: We have developed a new technique to track the evolution of the individual magnetic features from magnetograms, called "magnetic balltracking". It quantifies the flux of the tracked features, and it can track the footpoints of magnetic field lines inferred from magnetic field extrapolation. The algorithm can detect and quantify flux emergence, as well as flux cancellation. Results: The capabilities of magnetic balltracking are demonstrated with the detection and the tracking of two cases of magnetic flux emergence that lead to the br...

  15. Thin Magnetically Soft Wires for Magnetic Microsensors

    Directory of Open Access Journals (Sweden)

    Arcady Zhukov

    2009-11-01

    Full Text Available Recent advances in technology involving magnetic materials require development of novel advanced magnetic materials with improved magnetic and magneto-transport properties and with reduced dimensionality. Therefore magnetic materials with outstanding magnetic characteristics and reduced dimensionality have recently gained much attention. Among these magnetic materials a family of thin wires with reduced geometrical dimensions (of order of 1–30 μm in diameter have gained importance within the last few years. These thin wires combine excellent soft magnetic properties (with coercivities up to 4 A/m with attractive magneto-transport properties (Giant Magneto-impedance effect, GMI, Giant Magneto-resistance effect, GMR and an unusual re-magnetization process in positive magnetostriction compositions exhibiting quite fast domain wall propagation. In this paper we overview the magnetic and magneto-transport properties of these microwires that make them suitable for microsensor applications.

  16. Magnetic Storms

    Science.gov (United States)

    Tsurutani, Bruce T.; Gonzalez, Walter D.

    1998-01-01

    One of the oldest mysteries in geomagnetism is the linkage between solar and geomagnetic activity. The 11-year cycles of both the numbers of sunspots and Earth geomagnetic storms were first noted by Sabine. A few years later, speculation on a causal relationship between flares and storms arose when Carrington reported that a large magnetic storm followed the great September 1859 solar flare. However, it was not until this century that a well-accepted statistical survey on large solar flares and geomagnetic storms was performed, and a significant correlation between flares and geomagnetic storms was noted. Although the two phenomena, one on the Sun and the other on the Earth, were statistically correlated, the exact physical linkage was still an unknown at this time. Various hypotheses were proposed, but it was not until interplanetary spacecraft measurements were available that a high-speed plasma stream rich in helium was associated with an intense solar flare. The velocity of the solar wind increased just prior to and during the helium passage, identifying the solar ejecta for the first time. Space plasma measurements and Skylab's coronagraph images of coronal mass elections (CMES) from the Sun firmly established the plasma link between the Sun and the Earth. One phenomenon associated with magnetic storms is brilliant "blood" red auroras, as shown.

  17. MAGNETIC WOVEN FABRICS - PHYSICAL AND MAGNETIC PROPERTIES

    Directory of Open Access Journals (Sweden)

    GROSU Marian C

    2015-05-01

    Full Text Available A coated material is a composite structure that consists of at least two components: base material and coating layer. The purpose of coating is to provide special properties to base material, with potential to be applied in EMI shielding and diverse smart technical fields. This paper reports the results of a study about some physical and magnetic properties of coated woven fabrics made from cotton yarns with fineness of 17 metric count. For this aim, a plain woven fabric was coated with a solution hard magnetic polymer based. As hard magnetic powder, barium hexaferrite (BaFe12O19 was selected. The plain woven fabric used as base has been coated with five solutions having different amounts of hard magnetic powder (15% - 45% in order to obtain five different magnetic woven fabrics. A comparison of physical properties regarding weight (g/m2, thickness (mm, degree of charging (% and magnetic properties of magnetic woven samples were presented. Saturation magnetizing (emu/g, residual magnetizing (emu/g and coercive force (kA/m of pure hard magnetic powder and woven fabrics have been studied as hysteresis characteristics. The magnetic properties of the woven fabrics depend on the mass percentage of magnetic powder from coating solution. Also, the residual magnetism and coercive field of woven fabrics represents only a part of bulk barium hexafferite residual magnetism and coercive field.

  18. Magnetic Nano-structures

    Institute of Scientific and Technical Information of China (English)

    姚永德

    2004-01-01

    Fabrication of magnetic nano-structures with dots array and wires has been paid attention recently due to the application of high-density magnetic recording. In this study, we fabricated the magnetic dots array and wires through several ways that ensure the arrangement of magnetic dots and wires to be the structures we designed. Their magnetic properties are studied experimentally.

  19. Magnetic quantum dots and magnetic edge states

    International Nuclear Information System (INIS)

    Starting with defining the magnetic edge state in a magnetic quantum dot, which becomes quite popular nowadays conjunction with a possible candidate for a high density memory device or spintronic materials, various magnetic nano-quantum structures are reviewed in detail. We study the magnetic edge states of the two dimensional electron gas in strong perpendicular magnetic fields. We find that magnetic edge states are formed along the boundary of the magnetic dot, which is formed by a nonuniform distribution of magnetic fields. These magnetic edge states circulate either clockwise or counterclockwise, depending on the number of missing flux quanta, and exhibit quite different properties, as compared to the conventional ones which are induced by electrostatic confinements in the quantum Hall system. We also find that a close relation between the quantum mechanical eigenstates and the classical trajectories in the magnetic dot. When a magnetic dot is located inside a quantum wire, the edge-channel scattering mechanism by the magnetic quantum dot is very different from that by electrostatic dots. Here, the magnetic dot is formed by two different magnetic fields inside and outside the dot. We study the ballistic edge-channel transport and magnetic edge states in this situation. When the inner field is parallel to the outer one, the two-terminal conductance is quantized and shows the features of a transmission barrier and a resonator. On the other hand, when the inner field is reversed, the conductance is not quantized and all channels can be completely reflected in some energy ranges. The difference between the above two cases results from the distinct magnetic confinements. We also describe successfully the edge states of magnetic quantum rings and others in detail

  20. Magnetism of Carbonados

    Science.gov (United States)

    Kletetschka, G.; Taylor, P. T.; Wasilewski, P. J.

    2000-01-01

    Origin of Carbonado is not clear. Magnetism of Carbonado comes from the surface, indicating contemporary formation of both the surface and magnetic carriers. The interior of carbonado is relatively free of magnetic phases.

  1. MRI (Magnetic Resonance Imaging)

    Science.gov (United States)

    ... Procedures Medical Imaging MRI (Magnetic Resonance Imaging) MRI (Magnetic Resonance Imaging) Share Tweet Linkedin Pin it More sharing options ... 8 MB) Also available in Other Language versions . Magnetic Resonance Imaging (MRI) is a medical imaging procedure for making ...

  2. Magnetic nanoparticle motion in external magnetic field

    International Nuclear Information System (INIS)

    A set of equations describing the motion of a free magnetic nanoparticle in an external magnetic field in a vacuum, or in a medium with negligibly small friction forces is postulated. The conservation of the total particle momentum, i.e. the sum of the mechanical and the total spin momentum of the nanoparticle is taken into account explicitly. It is shown that for the motion of a nanoparticle in uniform magnetic field there are three different modes of precession of the unit magnetization vector and the director that is parallel the particle easy anisotropy axis. These modes differ significantly in the precession frequency. For the high-frequency mode the director points approximately along the external magnetic field, whereas the frequency and the characteristic relaxation time of the precession of the unit magnetization vector are close to the corresponding values for conventional ferromagnetic resonance. On the other hand, for the low-frequency modes the unit magnetization vector and the director are nearly parallel and rotate in unison around the external magnetic field. The characteristic relaxation time for the low-frequency modes is remarkably long. This means that in a rare assembly of magnetic nanoparticles there is a possibility of additional resonant absorption of the energy of alternating magnetic field at a frequency that is much smaller compared to conventional ferromagnetic resonance frequency. The scattering of a beam of magnetic nanoparticles in a vacuum in a non-uniform external magnetic field is also considered taking into account the precession of the unit magnetization vector and director. - Highlights: • There are three different modes of the unit magnetization vector precession for a free magnetic nanoparticle in uniform external magnetic field. • The high-frequency mode is similar to the conventional ferromagnetic resonance. The frequencies of the low-frequency modes can be two orders of magnitude lower. • The characteristic relaxation

  3. Magnetic Propeller for Uniform Magnetic Field Levitation

    OpenAIRE

    Krinker, Mark; Bolonkin, Alexander

    2008-01-01

    Three new approaches to generating thrust in uniform magnetic fields are proposed. The first direction is based on employing Lorentz force acting on partial magnetically shielded 8-shaped loop with current in external magnetic field, whereby a net force rather than a torque origins. Another approach, called a Virtual Wire System, is based on creating a magnetic field having an energetic symmetry (a virtual wire), with further superposition of external field. The external field breaks the symm...

  4. Magnetic resonance angiography

    Science.gov (United States)

    MRA; Angiography - magnetic resonance ... Kwong RY. Cardiovascular Magnetic Resonance Imaging. In: Bonow RO, Mann DL, Zipes DP, Libby P, eds. Braunwald's Heart Disease: A Textbook of Cardiovascular Medicine . ...

  5. Low-Dose-Rate Computed Tomography System Utilizing 25 mm/s-Scan Silicon X-ray Diode and Its Application to Iodine K-Edge Imaging Using Filtered Bremsstrahlung Photons

    Science.gov (United States)

    Matsushita, Ryo; Sato, Eiichi; Yanbe, Yutaka; Chiba, Hiraku; Maeda, Tomoko; Hagiwara, Osahiko; Matsukiyo, Hiroshi; Osawa, Akihiro; Enomoto, Toshiyuki; Watanabe, Manabu; Kusachi, Shinya; Sato, Shigehiro; Ogawa, Akira; Onagawa, Jun

    2013-03-01

    A low-dose-rate X-ray computed tomography (CT) system is useful for reducing absorbed dose for patients. The CT system with a tube current of sub-mA was developed using a silicon X-ray diode (Si-XD). The Si-XD is a high-sensitivity Si photodiode (PD) selected for detecting X-ray photons, and the X-ray sensitivity of the Si-XD was twice as high as that of Si-PD cerium-doped yttrium aluminum perovskite [YAP(Ce)]. X-ray photons are directly detected using the Si-XD without a scintillator, and the photocurrent from the diode is amplified using current-voltage and voltage-voltage amplifiers. The output voltage is converted into logical pulses using a voltage-frequency converter with a maximum frequency of 500 kHz, and the frequency is proportional to the voltage. The pulses from the converter are sent to the differentiator with a time constant of 500 ns to generate short positive pulses for counting, and the pulses are counted using a counter card. Tomography is accomplished by repeated linear scans and rotations of an object, and projection curves of the object are obtained by the linear scan. The exposure time for obtaining a tomogram was 5 min at a scan step of 0.5 mm and a rotation step of 3.0°. The tube current and voltage were 0.55 mA and 60 kV, respectively, and iodine K-edge CT was carried out using filtered bremsstrahlung X-ray spectra with a peak energy of 38 keV.

  6. X-ray Polarization Signatures of Compton Scattering in Magnetic Cataclysmic Variables

    CERN Document Server

    McNamara, Aimee; Wu, Kinwah

    2008-01-01

    Compton scattering within the accretion column of magnetic cataclysmic variables (mCVs) can induce a net polarization in the X-ray emission. We investigate this process using Monte Carlo simulations and find that significant polarization can arise as a result of the stratified flow structure in the shock-ionized column. We find that the degree of linear polarization can reach levels up to ~8% for systems with high accretion rates and low white-dwarf masses, when viewed at large inclination angles with respect to the accretion column axis. These levels are substantially higher than previously predicted estimates using an accretion column model with uniform density and temperature. We also find that for systems with a relatively low-mass white dwarf accreting at a high accretion rate, the polarization properties may be insensitive to the magnetic field, since most of the scattering occurs at the base of the accretion column where the density structure is determined mainly by bremsstrahlung cooling instead of cy...

  7. Integrated magnetic transformer assembly

    DEFF Research Database (Denmark)

    2014-01-01

    The present invention relates to an integrated magnetics transformer assembly comprising a first magnetically permeable core forming a first substantially closed magnetic flux path and a second magnetically permeable core forming a second substantially closed magnetic flux path. A first input...... inductor winding is wound around a first predetermined segment of the first magnetically permeable core and a second input inductor winding is wound around a first predetermined segment of the second magnetically permeable core. The integrated magnetics transformer assembly further comprises a first output......-winding of the first output inductor winding and the first half-winding of the second output inductor winding are configured to produce aligned, i.e. in the same direction, magnetic fluxes through the first substantially closed magnetic flux path. The integrated magnetics transformer assembly is well- suited for use...

  8. An optimized magnet for magnetic refrigeration

    DEFF Research Database (Denmark)

    Bjørk, Rasmus; Bahl, Christian Robert Haffenden; Smith, Anders;

    2010-01-01

    of the actual magnet. The final design generates a peak value of 1.24 T, an average flux density of 0.9 T in a volume of 2 L using only 7.3 L of magnet, and has an average low flux density of 0.08 T also in a 2 L volume. The working point of all the permanent magnet blocks in the design is very close...... to the maximum energy density. The final design is characterized in terms of a performance parameter, and it is shown that it is one of the best performing magnet designs published for magnetic refrigeration....

  9. Magnetic domains the analysis of magnetic microstructures

    CERN Document Server

    Hubert, Alex

    1998-01-01

    The book gives a systematic and comprehensive survey of the complete area of magnetic microstructures. It reaches from micromagnetism of nanoparticles to complex structures of extended magnetic materials. The book starts with a comprehensive evaluation of traditional and modern experimental methods for the observation of magnetic domains and continues with the treatment of important methods for the theoretical analysis of magnetic microcstructures. A survey of the necessary techniques in materials characterization is given. The book offers an observation and analysis of magnetic domains in all

  10. Environmental magnetism

    CERN Document Server

    Thompson, Roy

    1986-01-01

    The scientist will be forced, in the unenthusiastic words of one of my scientific colleagues, 'to slosh about in the primordial ooze known as inter-disciplinary studies'. John Passmore Man's responsibility for nature The present text has arisen from some thirteen years advances in our perception, appraisal and creative use of collaboration between the two authors. During that of order in natural systems. Out of this can come period, upwards of a dozen postgraduates in enhanced insight into processes, structures and Edinburgh, the New University of Ulster and Liver­ systems interactions on all temporal and spatial scales pool have been closely involved in exploring many of and at all integrative levels from subatomic to cosmic. the applications of magnetic measurements described In the environment, elements of order are often in the second half of the book. Much of the text is difficult to appraise and analyse, not only because of based on their work, both published and unpublished. intrinsic complexity, but ...

  11. Magnetic multilayer structure

    Energy Technology Data Exchange (ETDEWEB)

    Herget, Philipp; O' Sullivan, Eugene J.; Romankiw, Lubomyr T.; Wang, Naigang; Webb, Bucknell C.

    2016-07-05

    A mechanism is provided for an integrated laminated magnetic device. A substrate and a multilayer stack structure form the device. The multilayer stack structure includes alternating magnetic layers and diode structures formed on the substrate. Each magnetic layer in the multilayer stack structure is separated from another magnetic layer in the multilayer stack structure by a diode structure.

  12. Magnetic effects in electrochemistry

    Directory of Open Access Journals (Sweden)

    NEBOJSA D. NIKOLIC

    2005-05-01

    Full Text Available The effect of imposed magnetic fields onto the electrodeposition of magnetic (nickel and non – magnetic (copper metals was analysed. Also, magnetic properties of electrochemically obtained nanocontacts were examined. An effort to establish a possible correlation between the morphologies of the nanocontacts and the effect of the very large ballistic magnetoresistance (BMR effect was made.

  13. Superconducting magnets 1992

    International Nuclear Information System (INIS)

    This report discusses the following topics on Superconducting Magnets; SSC Magnet Industrialization; Collider Quadrupole Development; A Record-Setting Magnet; D20: The Push Beyond 10T; Nonaccelerator Applications; APC Materials Development; High-Tc at Low Temperature; Cable and Cabling-Machine Development; and Analytical Magnet Design

  14. A Magnetic Paradox

    Science.gov (United States)

    Arndt, Ebe

    2006-01-01

    Two recent articles in this journal described how an air core solenoid connected to an ac power source may restore the magnetization of a bar magnet with an alternating magnetic field (see Figs. 1 and 2). Although we are quite accustomed to using a constant magnetic field in an air core solenoid to remagnetize a ferromagnet, it is puzzling that we…

  15. Magnetic confinement

    Energy Technology Data Exchange (ETDEWEB)

    Batistoni, Paola; De Marco, Francesco; Pieroni, Leonardo (ed.)

    2005-07-01

    The Frascati Tokamak Upgrade (FTU) is a compact, high-magnetic-field tokamak capable of operating at density and magnetic field values similar to, or even encompassing, those of International Thermonuclear Experimental Reactor (ITER) and therefore provides a unique opportunity to explore physics issues that are directly relevant to ITER. During 2004 the experimental activities were focussed on fully exploiting the lower hybrid system (for generating and controlling the plasma current) and the electron cyclotron heating system (joint experiment with the Institute of Plasma Physics of the National Research Council, Milan). With all four gyrotrons in operation, full electron cyclotron power was achieved up to a record level of 1.5 MW. By simultaneously injecting lower hybrid waves, to tailor the plasma current radial profile, and electron cyclotron waves, to heat the plasma centre, good confinement regimes with internal transport barriers were obtained at the highest plasma density values ever achieved for this operation regime (n {approx}1.5X10{sup 20}m{sup -3}). Specific studies were devoted to optimising the coupling of lower hybrid waves to the plasma (by real-time control of the plasma position) and to generating current by electron cyclotron current drive. The new scanning CO{sub 2} interferometer (developed by the Reversed Field Experiment Consortium) for high spatial and time resolution (1 cm/50 {mu}s) density profile measurements was extensively used. The Thomson scattering diagnostic was upgraded and enabled observation of scattered signals associated with the Confinement background plasma dynamics. As for theoretical studies on the dynamics of turbulence in plasmas, the transition from Bohm-like scaling to gyro-Bohm scaling of the local plasma diffusivity was demonstrated on the basis of a generalised four wave model (joint collaboration with Princeton Plasma Physics Laboratory and the University of California at Irvine). The transition from weak to strong

  16. High gradient magnetic separation

    International Nuclear Information System (INIS)

    In a process in which magnetic material is trapped in a filter disposed in a magnetic field, and is unloaded by passing a fluid through the filter in the absence of the initial magnetic field, the magnetic field is first reduced to an intermediate value to allow unloading of the more weakly magnetic particles, the more strongly magnetic particles being retained and subsequently unloaded by further reduction of the magnetic field. Stage by stage reduction of the magnetic field during unloading allows separation of different species from the mixture. As an example the method can be applied to the separation of uranium compounds from mine ores. The uranium compounds are magnetic, while most of the other constituents of the ore are non-magnetic. The starting material is a suspension of the ore. Water is used for unloading. The filter material in this case is stainless steel balls. (author)

  17. Magnetic Damping For Maglev

    OpenAIRE

    Zhu, S; Cai, Y.; Rote, D.M.; S.S. Chen

    1998-01-01

    Magnetic damping is one of the important parameters that control the response and stability of maglev systems. An experimental study to measure magnetic damping directly is presented. A plate attached to a permanent magnet levitated on a rotating drum was tested to investigate the effect of various parameters, such as conductivity, gap, excitation frequency, and oscillation amplitude, on magnetic damping. The experimental technique is capable of measuring all of the magnetic damping coefficie...

  18. Magnetic Damping For Maglev

    Directory of Open Access Journals (Sweden)

    S. Zhu

    1998-01-01

    Full Text Available Magnetic damping is one of the important parameters that control the response and stability of maglev systems. An experimental study to measure magnetic damping directly is presented. A plate attached to a permanent magnet levitated on a rotating drum was tested to investigate the effect of various parameters, such as conductivity, gap, excitation frequency, and oscillation amplitude, on magnetic damping. The experimental technique is capable of measuring all of the magnetic damping coefficients, some of which cannot be measured indirectly.

  19. Magnetic Induced Axion Mass

    CERN Document Server

    Campanelli, L

    2006-01-01

    We study the effect of a uniform magnetic field on the dynamics of axions. In particular, we show that the Peccei-Quinn symmetry is explicitly broken by the presence of an external magnetic field. This breaking is induced by the non-conservation of the magnetic helicity and generates an electromagnetic contribution to the axion mass. We compute the magnetic axion mass in one loop approximation, with no restriction on the intensity of the magnetic field, and including thermal effects.

  20. Ultrafast Magnetization Dynamics

    OpenAIRE

    Woodford, S.

    2008-01-01

    This thesis addresses ultrafast magnetization dynamics from a theoretical perspective. The manipulation of magnetization using the inverse Faraday effect has been studied, as well as magnetic relaxation processes in quantum dots. The inverse Faraday effect – the generation of a magnetic field by nonresonant, circularly polarized light – offers the possibility to control and reverse magnetization on a timescale of a few hundred femtoseconds. This is important both for the technological advant...

  1. Permanent magnet system of alpha magnetic spectrometer

    Institute of Scientific and Technical Information of China (English)

    陈和生

    2000-01-01

    Alpha magnetic spectrometer (AMS) is the first large magnetic spectrometer in space. Its precursor flight was completed successfully in June 1998. The key part of AMS is the permanent magnet system, which was built by the Institute of Electric Engineering, the Institute of High Energy Physics and the Chinese Academy of Launch Vehicle Technology. This system includes a permanent magnet made of high grade NdFeB and a support structure. The unique design of the permanent magnet based on the magic ring fulfills the severe requirements on the magnetic field leakage and the dipole moment for space experiments. The permanent magnet weighs about 2 tons, and provides a geometric acceptance of 0.6 m2·sr and an analyzing power BL2 of 0.135 T·m2. It works up to 40℃ without demagnetization. The main structure is a thin double shell, which undergoes the strong magnetic force and torque of the permanent magnet, as well as the large load during launching and landing. The permanent magnet system fulfills the requirem

  2. Permanent magnet system of alpha magnetic spectrometer

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Alpha magnetic spectrometer (AMS) is the first large magnetic spectrometer in space. Its precursor flight was completed successfully in June 1998. The key part of AMS is the permanent magnet system, which was built by the Institute of Electric Engineering, the Institute of High Energy Physics and the Chinese Academy of Launch Vehicle Technology. This system includes a permanent magnet made of high grade NdFeB and a support structure. The unique design of the permanent magnet based on the magic ring fulfills the severe requirements on the magnetic field leakage and the dipole moment for space experiments. The permanent magnet weighs about 2 tons, and provides a geometric acceptance of 0.6 m2 ·sr and an analyzing power BL2 of 0.135 T·m2. It works up to 40℃ without demagnetization. The main structure is a thin double shell, which undergoes the strong magnetic force and torque of the permanent magnet, as well as the large load during launching and landing. The permanent magnet system fulfills the requirements from AMS, and satisfies the strict safety standards of NASA.

  3. Advanced Magnetic Nanostructures

    CERN Document Server

    Sellmyer, David

    2006-01-01

    Advanced Magnetic Nanostructures is devoted to the fabrication, characterization, experimental investigation, theoretical understanding, and utilization of advanced magnetic nanostructures. Focus is on various types of 'bottom-up' and 'top-down' artificial nanostructures, as contrasted to naturally occurring magnetic nanostructures, such as iron-oxide inclusions in magnetic rocks, and to structures such as perfect thin films. Chapter 1 is an introduction into some basic concepts, such as the definitions of basic magnetic quantities. Chapters 2-4 are devoted to the theory of magnetic nanostructures, Chapter 5 deals with the characterization of the structures, and Chapters 6-10 are devoted to specific systems. Applications of advanced magnetic nanostructures are discussed in Chapters11-15 and, finally, the appendix lists and briefly discusses magnetic properties of typical starting materials. Industrial and academic researchers in magnetism and related areas such as nanotechnology, materials science, and theore...

  4. Magnetic infrasound sensor

    Science.gov (United States)

    Mueller, Fred M.; Bronisz, Lawrence; Grube, Holger; Nelson, David C.; Mace, Jonathan L.

    2006-11-14

    A magnetic infrasound sensor is produced by constraining a permanent magnet inside a magnetic potential well above the surface of superconducting material. The magnetic infrasound sensor measures the position or movement of the permanent magnet within the magnetic potential well, and interprets the measurements. Infrasound sources can be located and characterized by combining the measurements from one or more infrasound sensors. The magnetic infrasound sensor can be tuned to match infrasound source types, resulting in better signal-to-noise ratio. The present invention can operate in frequency modulation mode to improve sensitivity and signal-to-noise ratio. In an alternate construction, the superconductor can be levitated over a magnet or magnets. The system can also be driven, so that time resolved perturbations are sensed, resulting in a frequency modulation version with improved sensitivity and signal-to-noise ratio.

  5. Multifunctionality in molecular magnetism.

    Science.gov (United States)

    Pinkowicz, Dawid; Czarnecki, Bernard; Reczyński, Mateusz; Arczyński, Mirosław

    2015-01-01

    Molecular magnetism draws from the fundamental ideas of structural chemistry and combines them with experimental physics resulting in one of the highest profile current topics, namely molecular materials that exhibit multifunctionality. Recent advances in the design of new generations of multifunctional molecular magnets that retain the functions of the building blocks and exhibit non-trivial magnetic properties at higher temperatures provide promising evidence that they may be useful for the future construction of nanoscale devices. This article is not a complete review but is rather an introduction into thefascinating world of multifunctional solids with magnetism as the leitmotif. We provide a subjective selection and discussion of the most inspiring examples of multifunctional molecular magnets: magnetic sponges, guest-responsive magnets, molecular magnets with ionic conductivity, photomagnets and non-centrosymmetric and chiral magnets.

  6. Magnetic balltracking: Tracking the photospheric magnetic flux

    Science.gov (United States)

    Attie, R.; Innes, D. E.

    2015-02-01

    Context. One aspect of understanding the dynamics of the quiet Sun is to quantify the evolution of the flux within small-scale magnetic features. These features are routinely observed in the quiet photosphere and were given various names, such as pores, knots, magnetic patches. Aims: This work presents a new algorithm for tracking the evolution of the broad variety of small-scale magnetic features in the photosphere, with a precision equal to the instrumental resolution. Methods: We have developed a new technique to track the evolution of the individual magnetic features from magnetograms, called "magnetic balltracking". It quantifies the flux of the tracked features, and it can track the footpoints of magnetic field lines inferred from magnetic field extrapolation. The algorithm can detect and quantify flux emergence, as well as flux cancellation. Results: The capabilities of magnetic balltracking are demonstrated with the detection and the tracking of two cases of magnetic flux emergence that lead to the brightening of X-ray loops. The maximum emerged flux ranges from 1018 Mx to 1019 Mx (unsigned flux) when the X-ray loops are observed. Movies associated to Figs. 6 and 18 are available in electronic form at http://www.aanda.org

  7. Magnetic measurements of the XLS magnets

    International Nuclear Information System (INIS)

    The magnets designed and built for Phase 1 (200MeV) of the XLS (X-Ray Lithography Source) project have all been measured and characterized. In this paper, the measurement system designed and utilized for the Phase 1 180 degree dipole magnets is reviewed. Hall probe measurements of the two dipole magnets, with a field of 1.1 Tesla at 1200 amperes, are discussed and presented. Phase 2 (700MeV) of this project includes replacement of the two room temperature dipole magnets with superconducting dipoles (3.9Tesla). 3 figs., 1 tab

  8. Magnetic measurements of the XLS magnets

    Energy Technology Data Exchange (ETDEWEB)

    Solomon, L.; Galayda, J.; Sylvester, C.

    1991-01-01

    The magnets designed and built for Phase 1 (200MeV) of the XLS (X-Ray Lithography Source) project have all been measured and characterized. In this paper, the measurement system designed and utilized for the Phase 1 180 degree dipole magnets is reviewed. Hall probe measurements of the two dipole magnets, with a field of 1.1 Tesla at 1200 amperes, are discussed and presented. Phase 2 (700MeV) of this project includes replacement of the two room temperature dipole magnets with superconducting dipoles (3.9Tesla). 3 figs., 1 tab.

  9. Magnetic measurements of the XLS magnets

    International Nuclear Information System (INIS)

    The magnets designed and built for Phase 1 (200 MeV) of the XLS (X-Ray Lithography Source) project have all been measured and characterized. In this paper, the measurement system designed and utilized for the Phase 1 180 degree dipole magnets is reviewed. Hall probe measurements of the two dipole magnets, with a field of 1.1 Tesla at 1,200 amperes, are discussed and presented. Phase 2 (700 MeV) of this project includes replacement of the two room temperature dipole magnets with superconducting dipoles (3.9 Tesla)

  10. Tamper resistant magnetic stripes

    Science.gov (United States)

    Naylor, Richard Brian; Sharp, Donald J.

    1999-01-01

    This invention relates to a magnetic stripe comprising a medium in which magnetized particles are suspended and in which the encoded information is recorded by actual physical rotation or alignment of the previously magnetized particles within the flux reversals of the stripe which are 180.degree. opposed in their magnetic polarity. The magnetized particles are suspended in a medium which is solid, or physically rigid, at ambient temperatures but which at moderately elevated temperatures, such as 40.degree. C., is thinable to a viscosity permissive of rotation of the particles therein under applications of moderate external magnetic field strengths within acceptable time limits.

  11. Multilayered Magnetic Gelatin Membrane Scaffolds

    Science.gov (United States)

    Samal, Sangram K.; Goranov, Vitaly; Dash, Mamoni; Russo, Alessandro; Shelyakova, Tatiana; Graziosi, Patrizio; Lungaro, Lisa; Riminucci, Alberto; Uhlarz, Marc; Bañobre-López, Manuel; Rivas, Jose; Herrmannsdörfer, Thomas; Rajadas, Jayakumar; De Smedt, Stefaan; Braeckmans, Kevin; Kaplan, David L.; Dediu, V. Alek

    2016-01-01

    A versatile approach for the design and fabrication of multilayer magnetic scaffolds with tunable magnetic gradients is described. Multilayer magnetic gelatin membrane scaffolds with intrinsic magnetic gradients were designed to encapsulate magnetized bioagents under an externally applied magnetic field for use in magnetic-field-assisted tissue engineering. The temperature of the individual membranes increased up to 43.7 °C under an applied oscillating magnetic field for 70 s by magnetic hyperthermia, enabling the possibility of inducing a thermal gradient inside the final 3D multilayer magnetic scaffolds. On the basis of finite element method simulations, magnetic gelatin membranes with different concentrations of magnetic nanoparticles were assembled into 3D multilayered scaffolds. A magnetic-gradient-controlled distribution of magnetically labeled stem cells was demonstrated in vitro. This magnetic biomaterial–magnetic cell strategy can be expanded to a number of different magnetic biomaterials for various tissue engineering applications. PMID:26451743

  12. Magnetic viscosity studies in hard magnetic materials

    International Nuclear Information System (INIS)

    The magnetic viscosity behavior has been studied in several hard magnets with different magnetization reversal mechanisms including barium ferrite powders, Cu-Mn-Al, ferrite magnets, Nd-Fe-B, and SmCo5, Sm2(Co,Fe,Cu,Zr)17. The measurements were made with a vibrating sample magnetometer for times up to 60 s and a SQUID magnetometer for longer times in the range of 60--2300 s. For most of the samples the magnetization was found to vary logarithmically with time. The field and temperature dependence of the magnetic viscosity coefficient S was studied. Here, S was found to vary with the applied field and it usually peaked around the coercive field Hc. The measured values of Smax at 10 K range from 0.004 to 1.853 emu/g for Cu-Mn-Al and Sm2(Co,Fe,Cu,Zr)17, respectively. The magnetic viscosity coefficient was used together with the magnetic susceptibility to determine the activation volume

  13. Active Magnetic Bearings – Magnetic Forces

    DEFF Research Database (Denmark)

    Kjølhede, Klaus

    2006-01-01

    of the magnetic forces are led by using different experimental tests: (I) by using hall sensors mounted directly on the poles (precise measurements of the magnetic flux) and by an auxiliary system, composed of strain gages and flexible beams attached to the rotor; (II) by measuring the input current and bearing......Parameter identification procedures and model validation are major steps towards intelligent machines supported by active magnetic bearings (AMB). The ability of measuring the electromagnetic bearing forces, or deriving them from measuring the magnetic flux, strongly contributes to the model...... of the work is the characterization of magnetic forces by using two experimental different experimental approaches. Such approaches are investigated and described in details. A special test rig is designed where the 4 poles - AMB is able to generate forces up to 1900 N. The high precision characterization...

  14. ISR magnet power supplies

    CERN Multimedia

    1970-01-01

    At the left, for the main magnets, the 18 kV switchgear is in the foreground and at the rear are cubicles with rectifiers and filters. At the right, rear, are rectifiers for pole face windings and auxiliary magnets.

  15. Boulder Magnetic Observatory

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — These data are vector and scalar component values of the Earth's magnetic field for 2004 recorded at the Boulder Magnetic Observatory in Colorado. Vector values are...

  16. An integrated magnetics component

    DEFF Research Database (Denmark)

    2013-01-01

    The present invention relates to an integrated magnetics component comprising a magnetically permeable core comprising a base member extending in a horizontal plane and first, second, third and fourth legs protruding substantially perpendicularly from the base member. First, second, third and...... fourth output inductor windings are wound around the first, second, third and fourth legs, respectively. A first input conductor of the integrated magnetics component has a first conductor axis and extends in-between the first, second, third and fourth legs to induce a first magnetic flux through a first...... flux path of the magnetically permeable core. A second input conductor of the integrated magnetics component has a second coil axis extending substantially perpendicularly to the first conductor axis to induce a second magnetic flux through a second flux path of the magnetically permeable core...

  17. Magnetic Graphene Nanohole Superlattices

    CERN Document Server

    Yu, Decai; Liu, Miao; Liu, Wei; Liu, Feng

    2008-01-01

    We investigate the magnetic properties of nano-holes (NHs) patterned in graphene using first principles calculations. We show that superlattices consisting of a periodic array of NHs form a new family of 2D crystalline "bulk" magnets whose collective magnetic behavior is governed by inter-NH spin-spin interaction. They exhibit long-range magnetic order well above room temperature. Furthermore, magnetic semiconductors can be made by doping magnetic NHs into semiconducting NH superlattices. Our findings offer a new material system for fundamental studies of spin-spin interaction and magnetic ordering in low dimensions, and open up the exciting opportunities of making engineered magnetic materials for storage media and spintronics applications.

  18. Magnetic field mapper

    Science.gov (United States)

    Masters, R. M.; Stenger, F. J.

    1969-01-01

    Magnetic field mapper locates imperfections in cadmium sulphide solar cells by detecting and displaying the variations of the normal component of the magnetic field resulting from current density variations. It can also inspect for nonuniformities in other electrically conductive materials.

  19. Magnetic Separation in Romania

    OpenAIRE

    Rezlescu, Nicolae; Bradu, Elena-Brandusa; Iacob, Gheorghe; Badescu, Vasile; Iacob, Lavinia

    1986-01-01

    The utilization of the magnetic separators of foreign and Romanian source is presented and the most important achievements in research, engineering design and manufacturing activity concerning the magnetic separation in Romania are reviewed.

  20. Magnetic Separation in Czechoslovakia

    OpenAIRE

    Hencl, Vladimir

    1991-01-01

    The use of magnetic separation in various mineral processing facilities in Czechoslovakia is described. The manufacture of assorted types of magnetic separation machines is highlighted. Potential applications and research and development activities are discussed.

  1. Project Magnet 1996

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Project Magnet data include low altitude, high density individual track line surveys, high altitude vector data and regional magnetic anomaly grids.

  2. Active magnetic regenerator

    Science.gov (United States)

    Barclay, John A.; Steyert, William A.

    1982-01-01

    The disclosure is directed to an active magnetic regenerator apparatus and method. Brayton, Stirling, Ericsson, and Carnot cycles and the like may be utilized in an active magnetic regenerator to provide efficient refrigeration over relatively large temperature ranges.

  3. The magnetic genome project

    Science.gov (United States)

    Sanvito, Stefano

    2015-03-01

    Magnetic materials underpin a vast and diverse range of modern technologies, going from data storage to energy production and use. However, the choice of magnets for mainstream applications is limited to a few dozens and the development of a new high-performance magnetic compound is a long and often unpredictable process. Here we describe a systematic pathway to the discovery of novel magnetic materials for multiple applications, which demonstrates an unprecedented throughput and speed up in the discovery process. We have constructed a massive electronic structures library for Heusler alloys containing 236,856 materials. We have then extracted those magnetic compounds with specific electronic properties, such as half-metallicity and large magnetization density, and finally established whether these can be fabricated at thermodynamical equilibrium. Based on our analysis we have identified 249 stable new intermetallic Heuslers, including 21 new magnets. Our work paves the way for large scale design of novel magnetic materials at unprecedented speed.

  4. Magnetic induction hyperthermia

    Science.gov (United States)

    Nikiforov, V. N.

    2007-09-01

    A review of physical principles and experimental data on magnetic hyperthermia are presented. The main principles of magnetic hyperthermia are considered. Results of its application in the therapy of oncology diseases are presented.

  5. Magnetism basics and applications

    CERN Document Server

    Stefanita, Carmen-Gabriela

    2012-01-01

    This textbook is aimed at engineering students who are likely to come across magnetics applications in their professional practice. Whether designing lithography equipment containing ferromagnetic brushes, or detecting defects in aeronautics, some basic knowledge of 21st century magnetism is needed. From the magnetic tape on the pocket credit card to the read head in a personal computer, people run into magnetism in many products. Furthermore, in a variety of disciplines tools of the trade exploit magnetic principles, and many interdisciplinary laboratory research areas cross paths with magnetic phenomena that may seem mysterious to the untrained mind. Therefore, this course offers a broad coverage of magnetism topics encountered more often in this millenium, revealing key concepts on which many practical applications rest. Some traditional subjects in magnetism are discussed in the first half of the book, followed by areas likely to spark the curiosity of those more interested in today’s technological achi...

  6. Magnetic actuators and sensors

    CERN Document Server

    Brauer, John R

    2014-01-01

    An accessible, comprehensive guide on magnetic actuators and sensors, this fully updated second edition of Magnetic Actuators and Sensors includes the latest advances, numerous worked calculations, illustrations, and real-life applications. Covering magnetics, actuators, sensors, and systems, with updates of new technologies and techniques, this exemplary learning tool emphasizes computer-aided design techniques, especially magnetic finite element analysis, commonly used by today's engineers. Detailed calculations, numerous illustrations, and discussions of discrepancies make this text an inva

  7. Solar Magnetic Helicity

    Institute of Scientific and Technical Information of China (English)

    ZHANG Hongqi

    2011-01-01

    Helicities is topologically a measure of the structural complexity of the corresponding fields. The magnetic helicity can be separated into two kinds. One is the self helicity, which relates to the magnetic flux tubes twisted themselves. This helicity may be used to analyze the twisted magnetic flux loops. Another one is the mutual helicity, which relates to the different magnetic flux tubes linked to each other.

  8. Magnetic fusion technology

    CERN Document Server

    Dolan, Thomas J

    2014-01-01

    Magnetic Fusion Technology describes the technologies that are required for successful development of nuclear fusion power plants using strong magnetic fields. These technologies include: ? magnet systems, ? plasma heating systems, ? control systems, ? energy conversion systems, ? advanced materials development, ? vacuum systems, ? cryogenic systems, ? plasma diagnostics, ? safety systems, and ? power plant design studies. Magnetic Fusion Technology will be useful to students and to specialists working in energy research.

  9. Axial Halbach Magnetic Bearings

    Science.gov (United States)

    Eichenberg, Dennis J.; Gallo, Christopher A.; Thompson, William K.

    2008-01-01

    Axial Halbach magnetic bearings have been investigated as part of an effort to develop increasingly reliable noncontact bearings for future high-speed rotary machines that may be used in such applications as aircraft, industrial, and land-vehicle power systems and in some medical and scientific instrumentation systems. Axial Halbach magnetic bearings are passive in the sense that unlike most other magnetic bearings that have been developed in recent years, they effect stable magnetic levitation without need for complex active control.

  10. Magnetic Pulse Welding Technology

    OpenAIRE

    Ahmad K. Jassim

    2011-01-01

    In this paper, the benefits of using Magnetic Pulse machine which is belong to Non-conventional machine instead of conventional machine. Magnetic Pulse Technology is used for joining dissimilar metals, and for forming and cutting metals. It is a non contact technique. Magnetic field is used to generate impact magnetic pressure for welding and forming the work piece by converted the electrical energy to mechanical energy. It is enable us to design previously not possible by weld...

  11. Magnetic Force Microscopy

    NARCIS (Netherlands)

    Abelmann, Leon

    2010-01-01

    Principle of MFM: In magnetic force microscopy (MFM), the magnetic stray field above a very flat specimen, or sample, is detected by placing a small magnetic element, the tip, mounted on a cantilever spring very close to the surface of the sample (Figure 1). Typical dimensions are a cantilever lengt

  12. Magnetic polarizability of pion

    Science.gov (United States)

    Luschevskaya, E. V.; Solovjeva, O. E.; Teryaev, O. V.

    2016-10-01

    We explore the energy dependence of π mesons off the background Abelian magnetic field on the base of quenched SU(3) lattice gauge theory and calculate the magnetic dipole polarizability of charged and neutral pions for various lattice volumes and lattice spacings. The contribution of the magnetic hyperpolarizability to the neutral pion energy has been also found.

  13. Magnetism in meteorites

    Science.gov (United States)

    Herndon, J. M.; Rowe, M. W.

    1974-01-01

    An overview is presented of magnetism in meteorites. A glossary of magnetism terminology followed by discussion of the various techniques used for magnetism studies in meteorites are included. The generalized results from use of these techniques by workers in the field are described. A brief critical analysis is offered.

  14. Nanochemistry and magnetism

    Science.gov (United States)

    Buchachenko, A. L.

    2009-10-01

    An analysis of magnetism of nanochemical systems opens up new ways to creating ferromagnets from diamagnetic substances and new principles for constructing molecular ferromagnets, hybrid magnetic materials, and monomolecular magnets on the basis of high-spin molecules and complexes. Their use in spin computing is considered.

  15. Iron dominated magnets

    Energy Technology Data Exchange (ETDEWEB)

    Fischer, G.E.

    1985-07-01

    These two lectures on iron dominated magnets are meant for the student of accelerator science and contain general treatments of the subjects design and construction. The material is arranged in the categories: General Concepts and Cost Considerations, Profile Configuration and Harmonics, Magnetic Measurements, a few examples of ''special magnets'' and Materials and Practices. Extensive literature is provided.

  16. Magnetic Resonance Imaging (MRI)

    Science.gov (United States)

    ... How Can I Help a Friend Who Cuts? Magnetic Resonance Imaging (MRI) KidsHealth > For Teens > Magnetic Resonance Imaging (MRI) Print A A A Text Size What's ... Exam Safety Getting Your Results What Is MRI? Magnetic resonance imaging (MRI) is a type of safe, painless testing ...

  17. Iron dominated magnets

    International Nuclear Information System (INIS)

    These two lectures on iron dominated magnets are meant for the student of accelerator science and contain general treatments of the subjects design and construction. The material is arranged in the categories: General Concepts and Cost Considerations, Profile Configuration and Harmonics, Magnetic Measurements, a few examples of ''special magnets'' and Materials and Practices. Extensive literature is provided

  18. Magnetic hyperthermia with hard-magnetic nanoparticles

    Science.gov (United States)

    Kashevsky, Bronislav E.; Kashevsky, Sergey B.; Korenkov, Victor S.; Istomin, Yuri P.; Terpinskaya, Tatyana I.; Ulashchik, Vladimir S.

    2015-04-01

    Recent clinical trials of magnetic hyperthermia have proved, and even hardened, the Ankinson-Brezovich restriction as upon magnetic field conditions applicable to any site of human body. Subject to this restriction, which is harshly violated in numerous laboratory and small animal studies, magnetic hyperthermia can relay on rather moderate heat source, so that optimization of the whole hyperthermia system remains, after all, the basic problem predetermining its clinical perspectives. We present short account of our complex (theoretical, laboratory and small animal) studies to demonstrate that such perspectives should be related with the hyperthermia system based on hard-magnetic (Stoner-Wohlfarth type) nanoparticles and strong low-frequency fields rather than with superparamagnetic (Brownian or Neél) nanoparticles and weak high-frequency fields. This conclusion is backed by an analytical evaluation of the maximum absorption rates possible under the field restriction in the ideal hard-magnetic (Stoner-Wohlarth) and the ideal superparamagnetic (single relaxation time) systems, by theoretical and experimental studies of the dynamic magnetic hysteresis in suspensions of movable hard-magnetic particles, by producing nanoparticles with adjusted coercivity and suspensions of such particles capable of effective energy absorption and intratumoral penetration, and finally, by successful treatment of a mice model tumor under field conditions acceptable for whole human body.

  19. Magnetic hyperthermia with hard-magnetic nanoparticles

    International Nuclear Information System (INIS)

    Recent clinical trials of magnetic hyperthermia have proved, and even hardened, the Ankinson-Brezovich restriction as upon magnetic field conditions applicable to any site of human body. Subject to this restriction, which is harshly violated in numerous laboratory and small animal studies, magnetic hyperthermia can relay on rather moderate heat source, so that optimization of the whole hyperthermia system remains, after all, the basic problem predetermining its clinical perspectives. We present short account of our complex (theoretical, laboratory and small animal) studies to demonstrate that such perspectives should be related with the hyperthermia system based on hard-magnetic (Stoner–Wohlfarth type) nanoparticles and strong low-frequency fields rather than with superparamagnetic (Brownian or Neél) nanoparticles and weak high-frequency fields. This conclusion is backed by an analytical evaluation of the maximum absorption rates possible under the field restriction in the ideal hard-magnetic (Stoner–Wohlarth) and the ideal superparamagnetic (single relaxation time) systems, by theoretical and experimental studies of the dynamic magnetic hysteresis in suspensions of movable hard-magnetic particles, by producing nanoparticles with adjusted coercivity and suspensions of such particles capable of effective energy absorption and intratumoral penetration, and finally, by successful treatment of a mice model tumor under field conditions acceptable for whole human body. - Highlights: • Hard-magnetic nanoparticles are shown superior for hyperthetmia to superparamagnetic. • Optimal system parameters are found from magnetic reversal model in movable particle. • Penetrating suspension of HM particles with aggregation-independent SAR is developed. • For the first time, mice with tumors are healed in AC field acceptable for human body

  20. Magnetic hyperthermia with hard-magnetic nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Kashevsky, Bronislav E., E-mail: bekas@itmo.by [A.V Luikov Heat and Mass Transfer Institute, Belarus Academy of Sciences, P. Brovka str. 15, Minsk 220072 (Belarus); Kashevsky, Sergey B.; Korenkov, Victor S. [A.V Luikov Heat and Mass Transfer Institute, Belarus Academy of Sciences, P. Brovka str. 15, Minsk 220072 (Belarus); Istomin, Yuri P. [N. N. Alexandrov National Cancer Center of Belarus, Lesnoy-2, Minsk 223040 (Belarus); Terpinskaya, Tatyana I.; Ulashchik, Vladimir S. [Institute of Physiology, Belarus Academy of Sciences, Akademicheskaya str. 28, Minsk 220072 (Belarus)

    2015-04-15

    Recent clinical trials of magnetic hyperthermia have proved, and even hardened, the Ankinson-Brezovich restriction as upon magnetic field conditions applicable to any site of human body. Subject to this restriction, which is harshly violated in numerous laboratory and small animal studies, magnetic hyperthermia can relay on rather moderate heat source, so that optimization of the whole hyperthermia system remains, after all, the basic problem predetermining its clinical perspectives. We present short account of our complex (theoretical, laboratory and small animal) studies to demonstrate that such perspectives should be related with the hyperthermia system based on hard-magnetic (Stoner–Wohlfarth type) nanoparticles and strong low-frequency fields rather than with superparamagnetic (Brownian or Neél) nanoparticles and weak high-frequency fields. This conclusion is backed by an analytical evaluation of the maximum absorption rates possible under the field restriction in the ideal hard-magnetic (Stoner–Wohlarth) and the ideal superparamagnetic (single relaxation time) systems, by theoretical and experimental studies of the dynamic magnetic hysteresis in suspensions of movable hard-magnetic particles, by producing nanoparticles with adjusted coercivity and suspensions of such particles capable of effective energy absorption and intratumoral penetration, and finally, by successful treatment of a mice model tumor under field conditions acceptable for whole human body. - Highlights: • Hard-magnetic nanoparticles are shown superior for hyperthetmia to superparamagnetic. • Optimal system parameters are found from magnetic reversal model in movable particle. • Penetrating suspension of HM particles with aggregation-independent SAR is developed. • For the first time, mice with tumors are healed in AC field acceptable for human body.

  1. Magnetism: a supramolecular function

    Energy Technology Data Exchange (ETDEWEB)

    Decurtins, S.; Pellaux, R.; Schmalle, H.W. [Zurich Univ., Inst. fuer Anorganische Chemie, Zurich (Switzerland)

    1996-11-01

    The field of molecule-based magnetism has developed tremendously in the last few years. Two different extended molecular - hence supramolecular -systems are presented. The Prussian-blue analogues show some of the highest magnetic ordering temperature of any class of molecular magnets, T{sub c} = 315 K, whereas the class of transition-metal oxalate-bridged compounds exhibits a diversity of magnetic phenomena. Especially for the latter compounds, the elastic neutron scattering technique has successfully been proven to trace the magnetic structure of these supramolecular and chiral compounds. (author) 18 figs., 25 refs.

  2. Magnetic nanocomposite sensor

    KAUST Repository

    Alfadhel, Ahmed

    2016-05-06

    A magnetic nanocomposite device is described herein for a wide range of sensing applications. The device utilizes the permanent magnetic behavior of the nanowires to allow operation without the application of an additional magnetic field to magnetize the nanowires, which simplifies miniaturization and integration into microsystems. In5 addition, the nanocomposite benefits from the high elasticity and easy patterning of the polymer-based material, leading to a corrosion-resistant, flexible material that can be used to realize extreme sensitivity. In combination with magnetic sensor elements patterned underneath the nanocomposite, the nanocomposite device realizes highly sensitive and power efficient flexible artificial cilia sensors for flow measurement or tactile sensing.

  3. Magnetic volumetric hologram memory with magnetic garnet.

    Science.gov (United States)

    Nakamura, Yuichi; Takagi, Hiroyuki; Lim, Pang Boey; Inoue, Mitsuteru

    2014-06-30

    Holographic memory is a promising next-generation optical memory that has a higher recording density and a higher transfer rate than other types of memory. In holographic memory, magnetic garnet films can serve as rewritable holographic memory media by use of magneto-optical effect. We have now demonstrated that a magnetic hologram can be recorded volumetrically in a ferromagnetic garnet film and that the signal image can be reconstructed from it for the first time. In addition, multiplicity of the magnetic hologram was also confirmed; the image could be reconstructed from a spot overlapped by other spots.

  4. Magnetism and metallurgy of soft magnetic materials

    CERN Document Server

    Chen, Chih-Wen

    2011-01-01

    Soft magnetic materials are economically and technologically the most important of all magnetic materials. In particular, the development of new materials and novel applications for the computer and telecommunications industries during the past few decades has immensely broadened the scope and altered the nature of soft magnetic materials. In addition to metallic substances, nonmetallic compounds and amorphous thin films are coming increasingly important. This thorough, well-organized volume - on of the most comprehensive treatments available - offers a coherent, logical presentation of the p

  5. Magnetic field synthesis for microwave magnetics

    Science.gov (United States)

    Morgenthaler, F. R.

    1982-04-01

    The Microwave and Quantum Magnetics Group of the M.I.T. Department of Electrical Engineering and Computer Science undertook a two-year research program directed at developing synthesis procedures that allow magnetostatic and/or magnetoelastic modes to be specially tailored for microwave signal processing applications that include magnetically tunable filters and limiters as well as delay lines that are either linearly dispersive or nondispersive over prescribed bandwidths. Special emphasis was given to devices employing thin films of yttrium iron garnet (YIG) that are blessed with spatially nonuniform dc magnetic fields.

  6. Benchmarking atomic physics models for magnetically confined fusion plasma physics experiments

    International Nuclear Information System (INIS)

    In present magnetically confined fusion devices, high and intermediate Z impurities are either puffed into the plasma for divertor radiative cooling experiments or are sputtered from the high Z plasma facing armor. The beneficial cooling of the edge as well as the detrimental radiative losses from the core of these impurities can be properly understood only if the atomic physics used in the modeling of the cooling curves is very accurate. To this end, a comprehensive experimental and theoretical analysis of some relevant impurities is undertaken. Gases (Ne, Ar, Kr, and Xe) are puffed and nongases are introduced through laser ablation into the FTU tokamak plasma. The charge state distributions and total density of these impurities are determined from spatial scans of several photometrically calibrated vacuum ultraviolet and x-ray spectrographs (3 - 1600 Angstrom), the multiple ionization state transport code transport code (MIST) and a collisional radiative model. The radiative power losses are measured with bolometery, and the emissivity profiles were measured by a visible bremsstrahlung array. The ionization balance, excitation physics, and the radiative cooling curves are computed from the Hebrew University Lawrence Livermore atomic code (HULLAC) and are benchmarked by these experiments. (Supported by U.S. DOE Grant No. DE-FG02-86ER53214 at JHU and Contract No. W-7405-ENG-48 at LLNL.) copyright 1999 American Institute of Physics

  7. Benchmarking atomic physics models for magnetically confined fusion plasma physics experiments

    Science.gov (United States)

    May, M. J.; Finkenthal, M.; Soukhanovskii, V.; Stutman, D.; Moos, H. W.; Pacella, D.; Mazzitelli, G.; Fournier, K.; Goldstein, W.; Gregory, B.

    1999-01-01

    In present magnetically confined fusion devices, high and intermediate Z impurities are either puffed into the plasma for divertor radiative cooling experiments or are sputtered from the high Z plasma facing armor. The beneficial cooling of the edge as well as the detrimental radiative losses from the core of these impurities can be properly understood only if the atomic physics used in the modeling of the cooling curves is very accurate. To this end, a comprehensive experimental and theoretical analysis of some relevant impurities is undertaken. Gases (Ne, Ar, Kr, and Xe) are puffed and nongases are introduced through laser ablation into the FTU tokamak plasma. The charge state distributions and total density of these impurities are determined from spatial scans of several photometrically calibrated vacuum ultraviolet and x-ray spectrographs (3-1600 Å), the multiple ionization state transport code transport code (MIST) and a collisional radiative model. The radiative power losses are measured with bolometery, and the emissivity profiles were measured by a visible bremsstrahlung array. The ionization balance, excitation physics, and the radiative cooling curves are computed from the Hebrew University Lawrence Livermore atomic code (HULLAC) and are benchmarked by these experiments. (Supported by U.S. DOE Grant No. DE-FG02-86ER53214 at JHU and Contract No. W-7405-ENG-48 at LLNL.)

  8. A new model for the X-ray continuum of the magnetized accreting pulsars

    CERN Document Server

    Farinelli, R; Bozzo, E; Becker, P A

    2016-01-01

    Accreting highly magnetized pulsars in binary systems are among the brightest X-ray emitters in our Galaxy. Although a number of high statistical quality broad-band (0.1-100 keV) X-ray observations are available, the spectral energy distribution of these sources is usually investigated by adopting pure phenomenological models, rather than models linked to the physics of accretion. In this paper, a detailed spectral study of the X-ray emission recorded from the high-mass X-ray binary pulsars Cen X-3, 4U 0115+63, and Her X-1 is carried out by using BeppoSAX and joined Suzaku+NuStar data, together with an advanced version of the compmag model. The latter provides a physical description of the high energy emission from accreting pulsars, including the thermal and bulk Comptonization of cyclotron and bremsstrahlung seed photons along the neutron star accretion column. The compmag model is based on an iterative method for solving second-order partial differential equations, whose convergence algorithm has been impr...

  9. Magnetically responsive enzyme powders

    Energy Technology Data Exchange (ETDEWEB)

    Pospiskova, Kristyna, E-mail: kristyna.pospiskova@upol.cz [Regional Centre of Advanced Technologies and Materials, Palacky University, Slechtitelu 11, 783 71 Olomouc (Czech Republic); Safarik, Ivo, E-mail: ivosaf@yahoo.com [Regional Centre of Advanced Technologies and Materials, Palacky University, Slechtitelu 11, 783 71 Olomouc (Czech Republic); Department of Nanobiotechnology, Institute of Nanobiology and Structural Biology of GCRC, Na Sadkach 7, 370 05 Ceske Budejovice (Czech Republic)

    2015-04-15

    Powdered enzymes were transformed into their insoluble magnetic derivatives retaining their catalytic activity. Enzyme powders (e.g., trypsin and lipase) were suspended in various liquid media not allowing their solubilization (e.g., saturated ammonium sulfate and highly concentrated polyethylene glycol solutions, ethanol, methanol, 2-propanol) and subsequently cross-linked with glutaraldehyde. Magnetic modification was successfully performed at low temperature in a freezer (−20 °C) using magnetic iron oxides nano- and microparticles prepared by microwave-assisted synthesis from ferrous sulfate. Magnetized cross-linked enzyme powders were stable at least for two months in water suspension without leakage of fixed magnetic particles. Operational stability of magnetically responsive enzymes during eight repeated reaction cycles was generally without loss of enzyme activity. Separation of magnetically modified cross-linked powdered enzymes from reaction mixtures was significantly simplified due to their magnetic properties. - Highlights: • Cross-linked enzyme powders were prepared in various liquid media. • Insoluble enzymes were magnetized using iron oxides particles. • Magnetic iron oxides particles were prepared by microwave-assisted synthesis. • Magnetic modification was performed under low (freezing) temperature. • Cross-linked powdered trypsin and lipase can be used repeatedly for reaction.

  10. Magnetically responsive enzyme powders

    International Nuclear Information System (INIS)

    Powdered enzymes were transformed into their insoluble magnetic derivatives retaining their catalytic activity. Enzyme powders (e.g., trypsin and lipase) were suspended in various liquid media not allowing their solubilization (e.g., saturated ammonium sulfate and highly concentrated polyethylene glycol solutions, ethanol, methanol, 2-propanol) and subsequently cross-linked with glutaraldehyde. Magnetic modification was successfully performed at low temperature in a freezer (−20 °C) using magnetic iron oxides nano- and microparticles prepared by microwave-assisted synthesis from ferrous sulfate. Magnetized cross-linked enzyme powders were stable at least for two months in water suspension without leakage of fixed magnetic particles. Operational stability of magnetically responsive enzymes during eight repeated reaction cycles was generally without loss of enzyme activity. Separation of magnetically modified cross-linked powdered enzymes from reaction mixtures was significantly simplified due to their magnetic properties. - Highlights: • Cross-linked enzyme powders were prepared in various liquid media. • Insoluble enzymes were magnetized using iron oxides particles. • Magnetic iron oxides particles were prepared by microwave-assisted synthesis. • Magnetic modification was performed under low (freezing) temperature. • Cross-linked powdered trypsin and lipase can be used repeatedly for reaction

  11. Tunneling magnetic force microscopy

    Science.gov (United States)

    Burke, Edward R.; Gomez, Romel D.; Adly, Amr A.; Mayergoyz, Isaak D.

    1993-01-01

    We have developed a powerful new tool for studying the magnetic patterns on magnetic recording media. This was accomplished by modifying a conventional scanning tunneling microscope. The fine-wire probe that is used to image surface topography was replaced with a flexible magnetic probe. Images obtained with these probes reveal both the surface topography and the magnetic structure. We have made a thorough theoretical analysis of the interaction between the probe and the magnetic fields emanating from a typical recorded surface. Quantitative data about the constituent magnetic fields can then be obtained. We have employed these techniques in studies of two of the most important issues of magnetic record: data overwrite and maximizing data-density. These studies have shown: (1) overwritten data can be retrieved under certain conditions; and (2) improvements in data-density will require new magnetic materials. In the course of these studies we have developed new techniques to analyze magnetic fields of recorded media. These studies are both theoretical and experimental and combined with the use of our magnetic force scanning tunneling microscope should lead to further breakthroughs in the field of magnetic recording.

  12. Molecule-based magnets

    Indian Academy of Sciences (India)

    J V Yakhmi

    2009-06-01

    The conventional magnetic materials used in current technology, such as, Fe, Fe2O3, Cr2O3, SmCo5, Nd2Fe14B etc are all atom-based, and their preparation/processing require high temperature routes. Employing self-assembly methods, it is possible to engineer a bulk molecular material with long-range magnetic order, mainly because one can play with the weak intermolecular interactions. Since the first successful synthesis of molecular magnets in 1986, a large variety of them have been synthesized, which can be categorized on the basis of the chemical nature of the magnetic units involved: organic-, metal-based systems, heterobimetallic assemblies, or mixed organic–inorganic systems. The design of molecule-based magnets has also been extended to the design of poly-functional molecular magnets, such as those exhibiting second-order optical nonlinearity, liquid crystallinity, or chirality simultaneously with long-range magnetic order. Solubility, low density and biocompatibility are attractive features of molecular magnets. Being weakly coloured, unlike their opaque classical magnet ‘cousins’ listed above, possibilities of photomagnetic switching exist. Persistent efforts also continue to design the ever-elusive polymer magnets towards applications in industry. While providing a brief overview of the field of molecular magnetism, this article highlights some recent developments in it, with emphasis on a few studies from the author’s own lab.

  13. Magnetic bearing and motor

    Science.gov (United States)

    Studer, Philip A. (Inventor)

    1983-01-01

    A magnetic bearing assembly (10) has an intermediate rotatable section (33) having an outer cylindrical member (30) coaxially suspended by a torsion wire (72) around an axially polarized cylindrical magnet (32). Axial alignment between the pole faces (40-43) of the intermediate section (33) and end surfaces (50-53) of opposed end bells (20, 22) provides a path of least reluctance across intervening air gaps (60-63) for the magnetic flux emanating from magnet (32). Radial dislocation increases the reluctance and creates a radial restoring force. Substitution of radially polarized magnets 107 fixed to a magnetically permeable cylinder (32') and insertion of pairs of armature coil windings (109-112) between the cylinder pair (33') provides an integral magnetic bearing and torsion motor (100) able to provide arcuately limited rotational drive.

  14. Magnetism in lanthanide superlattices

    DEFF Research Database (Denmark)

    Goff, J.P.; Sarthour, R.S.; McMorrow, D.F.;

    2000-01-01

    Neutron diffraction studies of heavy rare-earth superlattices have revealed the stabilization of novel magnetic phases chat are not present in bulk materials. The most striking result is the propagation of the magnetic ordering through nonmagnetic spacer materials. Here we describe some recent X......-ray magnetic resonant scattering studies of light rare-earth superlattices, which illuminate the mechanism of interlayer coupling, and provide access to different areas of Physics. such as the interplay between superconductivity and magnetism. Magnetic X-ray diffraction is found to be particularly well suited...... to the study of the modulated magnetic structures in superlattices, and provides unique information on the conduction-electron spin-density wave responsible for the propagation of magnetic order. (C) 2000 Elsevier Science B.V. All rights reserved....

  15. Magnetically recoverable nanocatalysts

    KAUST Repository

    Polshettiwar, Vivek

    2011-05-11

    A broad overview on magnetically recoverable nanocatalysts is presented and the use of magnetic nanomaterials as catalysts is discussed. Magnetic materials are used as organocatalysts and their applications range to challenging reactions, such as hydroformylation and olefin metathesis. Magnetic nanomaterials are also being used in environmental applications, such as for photo- and biocatalysis and for the adsorption and removal of pollutants from air and water. These materials show great promise as enantioselective catalysts, which are used extensively for the synthesis of medicines, drugs, and other bioactive molecules. By functionalizing these materials using chiral ligands, a series of chiral nanocatalysts can be designed, offering great potential to reuse these otherwise expensive catalyst systems. Characterization of magnetic catalysts is often a challenging task, and NMR characterization of these catalysts is difficult because the magnetic nature of the materials interferes with the magnetic field of the spectrometer.

  16. Magnetic Propeller for Uniform Magnetic Field Levitation

    CERN Document Server

    Krinker, Mark

    2008-01-01

    Three new approaches to generating thrust in uniform magnetic fields are proposed. The first direction is based on employing Lorentz force acting on partial magnetically shielded 8-shaped loop with current in external magnetic field, whereby a net force rather than a torque origins. Another approach, called a Virtual Wire System, is based on creating a magnetic field having an energetic symmetry (a virtual wire), with further superposition of external field. The external field breaks the symmetry causing origination of a net force. Unlike a wire with current, having radial energetic symmetry, the symmetry of the Virtual Wire System is closer to an axial wire. The third approach refers to the first two. It is based on creation of developed surface system, comprising the elements of the first two types. The developed surface approach is a way to drastically increase a thrust-to-weight ratio. The conducted experiments have confirmed feasibility of the proposed approaches.

  17. Magnetization arrangement of hard magnetic phases and mechanism of magnetization and reversal magnetization of nano-composite magnets

    Institute of Scientific and Technical Information of China (English)

    LIU Xin-cai; XIE Ren; PAN Jing

    2009-01-01

    During the process of directional solidification, laser remelting/solidification in the layer on sintered magnets, die-upsetting of cast magnets, or die-upsetting of nano-composites, the arrangements of the easy-magnetization-axes of the hard magnetic phases (Nd_2Fe_(14)B, SmCo_5 or Sm_2Co_(17) type) in their designed directions have been studied. In Fe-Pt nano-composite magnets, attempts have been taken to promote phase transformation from disordered, soft magnetic A1 to ordered, hard magnetic L_(10) FePt phase at reduced temperatures. The dependence of the magnetization and reversal magnetization processes on the microstructures, involving the morphology and three critical sizes of particles of the FePt nano-composite magnets, are summarized. With the decrease of the nominal thickness of the anisotropic FePt film epitaxially grown on the single crystal MgO (001) substrate, the reversal magnetization process firstly changes from full domain wall displacement to partial magnetic wall pinning related to the morphology change, where the coercive force increases abruptly. The reversal magnetization process secondly changes from magnetic wall pinning to incoherent magnetization rotation associated with the particles being below the first critical size at which multi-domain particles turn into single domain ones, where the coercive force is still increased. And the reversal magnetization mode thirdly changes from incoherent to coherent rotation referred to the second critical size, where the increase of the coercive force keeps on. However, when the particle size decreases to approach the third critical size where the particles turn into the supperparamagnetic state, the coercive force begins to decrease due to the interplay of the size effect and the incomplete ordering induced by the size effect. Meanwhile, due to the size effect, Curie temperature of the ultra-small FePt particles reduces.

  18. Magnetic Excitations and Magnetic Ordering in Praseodymium

    DEFF Research Database (Denmark)

    Houmann, Jens Christian Gylden; Chapellier, M.; Mackintosh, A. R.;

    1975-01-01

    The dispersion relations for magnetic excitons propagating on the hexagonal sites of double-hcp Pr provide clear evidence for a pronounced anisotropy in the exchange. The energy of the excitations decreases rapidly as the temperature is lowered, but becomes almost constant below about 7 K......, in agreement with a random-phase-approximation calculation. No evidence of magnetic ordering has been observed above 0.4 K, although the exchange is close to the critical value necessary for an antiferromagnetic state....

  19. MAGNETIC CIRCUIT EQUIVALENT OF THE SYNCHRONOUS MOTOR WITH INCORPORATED MAGNETS

    OpenAIRE

    Fyong Le Ngo; G. I. Gul’kov

    2015-01-01

    Magnetic circuitry computation is one of the central stages of designing a synchronous motor with incorporated magnets, which can be performed by means of a simplified method of the magnetic-circuits equivalent modeling. The article studies the magnetic circuit of the motor with the rotor-incorporated magnets, which includes four sectors: constant magnets with the field pole extension made of magnetically soft steel, magniflux dispersion sections containing air barriers and steel bridges; the...

  20. Review and comparison of magnet designs for magnetic refrigeration

    OpenAIRE

    Bjørk, Rasmus; Bahl, Christian Robert Haffenden; Smith, Anders; Pryds, Nini

    2014-01-01

    One of the key issues in magnetic refrigeration is generating the magnetic field that the magnetocaloric material must be subjected to. The magnet constitutes a major part of the expense of a complete magnetic refrigeration system and a large effort should therefore be invested in improving the magnet design. A detailed analysis of the efficiency of different published permanent magnet designs used in magnetic refrigeration applications is presented in this paper. Each design is analyzed base...

  1. Magnetic-seeding filtration

    Energy Technology Data Exchange (ETDEWEB)

    DePaoli, D.W.; Tsouris, C. [Oak Ridge National Lab., TN (United States); Yiacoumi, Sotira

    1997-10-01

    Magnetic-seeding filtration is a technology under development for the enhanced removal of magnetic and non-magnetic particulates from liquids. This process involves the addition of a small amount of magnetic seed particles (such as naturally occurring iron oxide) to a waste suspension, followed by treatment with a magnetic filter. Non-magnetic and weakly magnetic particles are made to undergo nonhomogeneous flocculation with the seed particles, forming flocs of high magnetic susceptibility that are readily removed by a conventional high-gradient magnetic filter. This technology is applicable to a wide range of liquid wastes, including groundwater, process waters, and tank supernatants. Magnetic-seeding filtration may be used in several aspects of treatment, such as (1) removal of solids, particularly those in the colloidal size range that are difficult to remove by conventional means; (2) removal of contaminants by precipitation processes; and (3) removal of contaminants by sorption processes. Waste stream characteristics for which the technology may be applicable include (1) particle sizes ranging from relatively coarse (several microns) to colloidal particles, (2) high or low radiation levels, (3) broad-ranging flow rates, (4) low to moderate solids concentration, (5) cases requiring high decontamination factors, and (6) aqueous or non-aqueous liquids. At this point, the technology is at the bench-scale stage of development; laboratory studies and fundamental modeling are currently being employed to determine the capabilities of the process.

  2. Magnetism in Medicine

    Science.gov (United States)

    Schenck, John

    2000-03-01

    For centuries physicians, scientists and others have postulated an important role, either as a cause of disease or as a mode of therapy, for magnetism in medicine. Although there is a straightforward role in the removal of magnetic foreign bodies, the majority of the proposed magnetic applications have been controversial and have often been attributed by mainstream practitioners to fraud, quackery or self-deception. Calculations indicate that many of the proposed methods of action, e.g., the field-induced alignment of water molecules or alterations in blood flow, are of negligible magnitude. Nonetheless, even at the present time, the use of small surface magnets (magnetotherapy) to treat arthritis and similar diseases is a widespread form of folk medicine and is said to involve sales of approximately one billion dollars per year. Another medical application of magnetism associated with Mesmer and others (eventually known as animal magnetism) has been discredited, but has had a culturally significant role in the development of hypnotism and as one of the sources of modern psychotherapy. Over the last two decades, in marked contrast to previous applications of magnetism to medicine, magnetic resonance imaging or MRI, has become firmly established as a clinical diagnostic tool. MRI permits the non-invasive study of subtle biological processes in intact, living organisms and approximately 150,000,000 diagnostic studies have been performed since its clinical introduction in the early 1980s. The dramatically swift and widespread acceptance of MRI was made possible by scientific and engineering advances - including nuclear magnetic resonance, computer technology and whole-body-sized, high field superconducting magnets - in the decades following World War Two. Although presently used much less than MRI, additional applications, including nerve and muscle stimulation by pulsed magnetic fields, the use of magnetic forces to guide surgical instruments, and imaging utilizing

  3. Remanent magnetism at Mars

    Science.gov (United States)

    Curtis, S. A.; Ness, N. F.

    1988-01-01

    It is shown that a strong case can be made for an intrinsic magnetic field of dynamo origin for Mars earlier in its history. The typical equatorial magnetic field intensity would have been equal to about 0.01-0.1 gauss. The earlier dynamo activity is no longer extant, but a significant remanent magnetic field may exist. A highly non-dipole magnetic field could result from the remanent magnetization of the surface. Remanent magnetization may thus play an important role in the Mars solar wind interactions, in contrast to Venus with its surface temperatures above the Curie point. The anomalous characteristics of Mars'solar wind interaction compared to that of Venus may be explicable on this basis.

  4. Passive magnetic bearing system

    Science.gov (United States)

    Post, Richard F.

    2014-09-02

    An axial stabilizer for the rotor of a magnetic bearing provides external control of stiffness through switching in external inductances. External control also allows the stabilizer to become a part of a passive/active magnetic bearing system that requires no external source of power and no position sensor. Stabilizers for displacements transverse to the axis of rotation are provided that require only a single cylindrical Halbach array in its operation, and thus are especially suited for use in high rotation speed applications, such as flywheel energy storage systems. The elimination of the need of an inner cylindrical array solves the difficult mechanical problem of supplying support against centrifugal forces for the magnets of that array. Compensation is provided for the temperature variation of the strength of the magnetic fields of the permanent magnets in the levitating magnet arrays.

  5. Superconducting accelerator magnet design

    International Nuclear Information System (INIS)

    Superconducting dipoles, quadrupoles and correction magnets are necessary to achieve the high magnetic fields required for big accelerators presently in construction or in the design phase. Different designs of superconducting accelerator magnets are described and the designs chosen at the big accelerator laboratories are presented. The most frequently used cosθ coil configuration is discussed in detail. Approaches for calculating the magnetic field quality including coil end fields are presented. Design details of the cables, coils, mechanical structures, yokes, helium vessels and cryostats including thermal radiation shields and support structures used in superconducting magnets are given. Necessary material properties are mentioned. Finally, the main results of magnetic field measurements and quench statistics are presented. (orig.)

  6. Magnetic heat pumping

    Science.gov (United States)

    Brown, G. V. (Inventor)

    1983-01-01

    The method employs ferromagnetic or ferromagnetic elements, preferably of rare-earth based material, for example gadolinium, and preferably employs a regenerator. The steps comprise controlling the temperature and applied magnetic field of the element to cause the state of the element as represented on a temperature-magnetic entropy diagram repeatedly to traverse a loop. The loop may have a first portion of concurrent substantially isothermal or constant temperature and increasing applied magnetic field, a second portion of lowering temperature and constant applied magnetic field, a third portion of isothermal and decreasing applied magnetic field, and a fourth portion of increasing temperature and constant applied magnetic field. Other loops may be four sided, with, for example, two isotherms and two adiabats (constant entropy portions.

  7. The First Magnetic Fields

    CERN Document Server

    Widrow, Lawrence M; Schleicher, Dominik; Subramanian, Kandaswamy; Tsagas, Christos G; Treumann, Rudolf A

    2011-01-01

    We review current ideas on the origin of galactic and extragalactic magnetic fields. We begin by summarizing observations of magnetic fields at cosmological redshifts and on cosmological scales. These observations translate into constraints on the strength and scale magnetic fields must have during the early stages of galaxy formation in order to seed the galactic dynamo. We examine mechanisms for the generation of magnetic fields that operate prior during inflation and during subsequent phase transitions such as electroweak symmetry breaking and the quark-hadron phase transition. The implications of strong primordial magnetic fields for the reionization epoch as well as the first generation of stars is discussed in detail. The exotic, early-Universe mechanisms are contrasted with astrophysical processes that generate fields after recombination. For example, a Biermann-type battery can operate in a proto-galaxy during the early stages of structure formation. Moreover, magnetic fields in either an early genera...

  8. Magnetic tension in cosmology

    CERN Document Server

    Tsagas, C G

    2001-01-01

    The vector nature of magnetic fields and the general relativistic geometrical interpretation of gravity lead to a unique coupling between magnetism and spacetime curvature, by effectively transferring the field properties into the spacetime itself. The key magnetic property appears to be the tension of the field lines. Combined with geometry, the magnetic tension triggers a range of rather unexpected effects with profound implications. The field suppresses or boosts density fluctuations depending on the strength of the curvature deformation. It can act as an effective cosmological constant or mimic a time-decaying quintessence. Moreover, even weak magnetic fields become key players when the curvature is strong. For instance, a seed field could halt the accelerated phase in certain inflationary models. The magnetic tension also damps gravity waves and shows an intriguing tendency to smooth out spatial curvature distortions. We describe the nature and the range of these effects and discuss their potential impli...

  9. Magnetic and viscoelastic response of elastomers with hard magnetic filler

    International Nuclear Information System (INIS)

    Magnetic elastomers (MEs) based on a silicone matrix and magnetically hard NdFeB particles have been synthesized and their magnetic and viscoelastic properties have been studied depending on the size and concentration of magnetic particles and the magnetizing field. It has been shown that magnetic particles can rotate in soft polymer matrix under applied magnetic field, this fact leading to some features in both magnetic and viscoelastic properties. In the maximum magnetic field used magnetization of MEs with smaller particles is larger while the coercivity is smaller due to higher mobility of the particles within the polymer matrix. Viscoelastic behavior is characterized by long relaxation times due to restructuring of the magnetic filler under the influence of an applied mechanical force and magnetic interactions. The storage and loss moduli of magnetically hard elastomers grow significantly with magnetizing field. The magnetic response of the magnetized samples depends on the mutual orientation of the external magnetic field and the internal sample magnetization. Due to the particle rotation within the polymer matrix, the loss factor increases abruptly when the magnetic field is turned on in the opposite direction to the sample magnetization, further decreasing with time. Moduli versus field dependences have minimum at non-zero field and are characterized by a high asymmetry with respect to the field direction. (paper)

  10. Waveform control pulse magnetization for HTS bulk magnet

    Science.gov (United States)

    Ida, Tetsuya; Shigeuchi, Koji; Okuda, Sayo; Watasaki, Masahiro; Izumi, Mitsuru

    2016-03-01

    For the past 10 years, we have studied high-temperature superconducting (HTS) bulk magnets for use in electromagnetic rotating machines. If the magnetic field effectively magnetizes the HTS bulk, then the size of the motor and generator can be reduced without a reduction in output. We showed that the melt-textured Gd-Ba-Cu-O HTS bulk effectively traps a high magnetic field using waveform control pulse magnetization (WCPM). WCPM makes it possible to generate any pulsed magnetic field waveform by appropriately changing the duty ratio of the pulse width modulation. By chopping so that the pulsed magnetic field has a period of about 1ms, the WCPM technology enables active control of the rise time and suppresses magnetic flux motion that decreases magnetization efficiency. This method is also useful for any HTS bulk magnet, and the high magnetic flux density is trapped in the HTS bulk by a single pulse magnetic field. We developed a magnetizer that has a feedback system from the penetrated magnetic flux density to realize WCPM. In this research, using only a single pulse magnetic field of WCPM method at 77K, an HTS bulk with a 45mm diameter and 19mm thickness trapped a maximum magnetic field of 1.63T, which is more than 90% of the trapped magnetic flux density by FC magnetization. This result suggests that the pulse magnetizing method can replace the conventional field-cooled method and promote the practical use of HTS magnets for electromagnetic power applications.

  11. Magnetic Spring Device

    OpenAIRE

    Hassam, A. B.; Rodgers, J. C.

    2009-01-01

    A cylindrical system is proposed that will store magnetic energy in a localized azimuthal field that can then be quickly released on Alfvenic timescales, accompanied by the formation of a flowing Z-pinch plasma. The magnetized plasma is MHD in character and will have unilateral axial momentum with Alfvenic speeds. Conventional plasma gun injectors (Marshall type) have a limited parameter space of operation. The "magnetic spring" momentum injector differs from Marshall guns in that it has an a...

  12. Magnetic latching solenoid

    Science.gov (United States)

    Marts, D.J.; Richardson, J.G.; Albano, R.K.; Morrison, J.L. Jr.

    1995-11-28

    This invention discloses a D.C. magnetic latching solenoid that retains a moving armature in a first or second position by means of a pair of magnets, thereby having a zero-power requirement after actuation. The first or second position is selected by reversing the polarity of the D.C. voltage which is enough to overcome the holding power of either magnet and transfer the armature to an opposite position. The coil is then de-energized. 2 figs.

  13. Magnetic conditioning in superfluid

    Energy Technology Data Exchange (ETDEWEB)

    Caspi, S.

    1988-08-01

    Improvements in superconducting magnet technology have reduced to a handful the number of training quenches typical of dipole magnets. The number of training quenches in long (17 m) and short (1--2 m) SSC magnets are now about the same (operating at 6.6 tesla and 4.4 K). Yet the steps necessary to totally eliminate training are in the future RandD plans for magnet construction and conductor motion prevention. The accepted hypothesis is that Lorentz forces and poor mechanical properties of superconducting cables are the cause of conductor motion. Conductor motion reduces the stored energy in the cable by converting it into heat. The small amount of heat generated (millijoules) during motion is usually enough to quench the magnet when it is close to short sample. During training, the magnet performance normally improves with the number of quenches. It is not the quench itself that improves magnet performance but rather the fact that once conductor motion has occurred it will probably not repeat itself unless subjected to higher forces. Conditioning is a process that enables the magnet to reduce its stored energy without causing a premature quench. During the conditioning process the magnet is further cooled from its operating temperature of 4.4 K to 1.8 K by converting He I into He II. As a result the magnet is placed in a state where it has excess stability as well as excellent heat transfer capabilities. Although this does not eliminate motion, if the magnet is now cycled to /approximately/10% above its operating field at 4.4 K (which is above short sample) the excess stability should be enough to prevent quenching and reduce the probability of conductor motion and training once the magnet has been warmed back up to its operating temperature of 4.4 K. 3 refs., 5 figs.

  14. SPS : the magnet system

    CERN Multimedia

    CERN Neyrac Films

    1974-01-01

    English version. Part of a series of films about the SPS. This one ois from May 1974 to December 1974. Roy Billinge, Vince Hatton explain about magnet system. Technical requirements, accuracy checks, installation, magnetic measurements, mechanical measurements. Discussion of a particular problem which can come from variation in the thickness of the vacuum chambers. Dipoles, quadrapoles and other speciality magnets. Necessity for close international cooperation to coordinate the work. Nice meeting sequence at end. (calculator on the table.)

  15. Magnetizing the universe

    OpenAIRE

    Subramanian, Kandaswamy

    2008-01-01

    The origin of cosmic magnetism is an issue of fundamental importance in astrophysics. We review here some of the ideas of how large scale magnetic fields in the universe, particularly in galaxies and galaxy clusters could arise. The popular paradigm involves the generation of a seed magnetic field followed by turbulent dynamo amplification of the seed field. We first outline various seed field generation mechanisms including Biermann batteries. These in general give a field much smaller than ...

  16. Magnetic Electrochemical Finishing Machining

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    How to improve the finishing efficiency and surface roughness have been all along the objective of research in electrochemical polishing. However, the research activity, i.e. during electrochemical polishing, directly introduce the magnetic field to study how the magnetic field influences on the finishing efficiency, quality and the electrochemical process in the field of finishing machining technology, is insufficient. When introducing additional magnetic field in the traditional electrochemical pol...

  17. Magnets in prosthetic dentistry.

    Science.gov (United States)

    Riley, M A; Walmsley, A D; Harris, I R

    2001-08-01

    Magnetic retention is a popular method of attaching removable prostheses to either retained roots or osseointegrated implants. This review chronicles the development of magnets in dentistry and summarizes future research in their use. The literature was researched by using the Science Citation Index and Compendex Web from 1981 to 2000. Articles published before 1981 were hand researched from citations in other publications. Articles that discussed the use of magnets in relation to prosthetic dentistry were selected.

  18. Magnetic Spring Device

    CERN Document Server

    Hassam, A B

    2009-01-01

    A cylindrical system is proposed that will store magnetic energy in a localized azimuthal field that can then be quickly released on Alfvenic timescales, accompanied by the formation of a flowing Z-pinch plasma. The magnetized plasma is MHD in character and will have unilateral axial momentum with Alfvenic speeds. Conventional plasma gun injectors (Marshall type) have a limited parameter space of operation. The "magnetic spring" momentum injector differs from Marshall guns in that it has an already stored strong magnetic field before release. The resulting parameter space is much broader. There are possible applications to momentum injectors for fusion and to plasma and rail guns.

  19. Covariant Magnetic Connection Hypersurfaces

    CERN Document Server

    Pegoraro, F

    2016-01-01

    In the single fluid, nonrelativistic, ideal-Magnetohydrodynamic (MHD) plasma description magnetic field lines play a fundamental role by defining dynamically preserved "magnetic connections" between plasma elements. Here we show how the concept of magnetic connection needs to be generalized in the case of a relativistic MHD description where we require covariance under arbitrary Lorentz transformations. This is performed by defining 2-D {\\it magnetic connection hypersurfaces} in the 4-D Minkowski space. This generalization accounts for the loss of simultaneity between spatially separated events in different frames and is expected to provide a powerful insight into the 4-D geometry of electromagnetic fields when ${\\bf E} \\cdot {\\bf B} = 0$.

  20. Covariant magnetic connection hypersurfaces

    Science.gov (United States)

    Pegoraro, F.

    2016-04-01

    > In the single fluid, non-relativistic, ideal magnetohydrodynamic (MHD) plasma description, magnetic field lines play a fundamental role by defining dynamically preserved `magnetic connections' between plasma elements. Here we show how the concept of magnetic connection needs to be generalized in the case of a relativistic MHD description where we require covariance under arbitrary Lorentz transformations. This is performed by defining 2-D magnetic connection hypersurfaces in the 4-D Minkowski space. This generalization accounts for the loss of simultaneity between spatially separated events in different frames and is expected to provide a powerful insight into the 4-D geometry of electromagnetic fields when .

  1. Magnetism v.5

    CERN Document Server

    Suhl, Harry

    1973-01-01

    Magnetism, Volume V: Magnetic Properties of Metallic Alloys deals with the magnetic properties of metallic alloys and covers topics ranging from conditions favoring the localization of effective moments to the s-d model and the Kondo effect, along with perturbative, scattering, and Green's function theories of the s-d model. Asymptotically exact methods used in addressing the Kondo problem are also described.Comprised of 12 chapters, this volume begins with a review of experimental results and phenomenology concerning the formation of local magnetic moments in metals, followed by a Har

  2. Magnetic Nernst effect

    Science.gov (United States)

    Brechet, Sylvain D.; Ansermet, Jean-Philippe

    2015-09-01

    The thermodynamics of irreversible processes in continuous media predicts the existence of a magnetic Nernst effect that results from a magnetic analog to the Seebeck effect in a ferromagnet and magnetophoresis occurring in a paramagnetic electrode in contact with the ferromagnet. Thus, a voltage that has DC and AC components is expected across a Pt electrode as a response to the inhomogeneous magnetic induction field generated by magnetostatic waves of an adjacent YIG slab subject to a temperature gradient. The voltage frequency and dependence on the orientation of the applied magnetic induction field are quite distinct from that of spin pumping.

  3. Manufacturing the MFTF magnet

    Energy Technology Data Exchange (ETDEWEB)

    Dalder, E.N.C.; Hinkle, R.E.; Hodges, A.J.

    1980-10-13

    The Mirror Fusion Test Facility (MFTF) is a large mirror program experiment for magnetic fusion energy. It will combine and extend the near-classical plasma confinement achieved in 2XIIB with advanced neutral-beam and magnet technologies. The product of ion density and confinement time will be improved more than an order of magnitude, while the superconducting magnet weight will be extrapolated from 15 tons in Baseball II to 375 tons in MFTF. Recent reactor studies show that the MFTF will traverse much of the distance in magnet technology towards the reactor regime.

  4. Magnetic Structure of Erbium

    DEFF Research Database (Denmark)

    Gibbs, D.; Bohr, Jakob; Axe, J. D.;

    1986-01-01

    We present a synchrotron x-ray scattering study of the magnetic phases of erbium. In addition to the magnetic scattering located at the fundamental wave vector τm we also observe scattering from magnetoelastically induced charge modulations at the fundamental wave vector, at twice the fundamental......, and at positions split symmetrically about the fundamental. As the temperature is lowered below 52 K the charge and magnetic scattering display a sequence of lock-in transitions to rational wave vectors. A spin-slip description of the magnetic structure is presented which explains the wave vectors...

  5. Magnetic S-parameter

    DEFF Research Database (Denmark)

    Sannino, Francesco

    2010-01-01

    We propose a direct test of the existence of gauge duals for nonsupersymmetric asymptotically free gauge theories developing an infrared fixed point by computing the S-parameter in the electric and dual magnetic description. In particular we show that at the lower bound of the conformal window...... the magnetic S-parameter, i.e. the one determined via the dual magnetic gauge theory, assumes a simple expression in terms of the elementary magnetic degrees of freedom. The results further support our recent conjecture of the existence of a universal lower bound on the S parameter and indicates...

  6. Optimal magnetic attitude control

    DEFF Research Database (Denmark)

    Wisniewski, Rafal; Markley, F.L.

    1999-01-01

    Magnetic torquing is attractive as means of control for small satellites. The actuation principle is to use the interaction between the earth's magnetic field and a magnetic field generated by a coil set in the satellite. This control principle is inherently time-varying, and difficult to use...... because control torques can only be generated perpendicular to the local geomagnetic field vector. This has been a serious obstacle for using magnetorquer based control for three-axis stabilization of a low earth orbit satellite. The problem of controlling the spacecraft attitude using only magnetic...

  7. LHCb experiment magnets

    CERN Multimedia

    Maximilien Brice

    2004-01-01

    The leading members of the LHCb magnet project, from left to right: Pierre-Ange Giudici, who organized and supervised the industrial production of the coils; Marcello Losasso, who performed the 3D calculations to optimise the magnetic field; Olivier Jamet, responsible for the 3D design; Jean Renaud, in charge of the magnet assembly, and Wilfried Flegel, project leader. The LHCb detector will investigate matter-antimatter differences in B mesons at the LHC. The coils of the detector's huge dipole magnet are seen here in April 2004.

  8. Engineering magnetism in semiconductors

    Directory of Open Access Journals (Sweden)

    Tomasz Dietl

    2006-11-01

    Full Text Available Transition metal doped III-V, II-VI, and group IV compounds offer an unprecedented opportunity to explore ferromagnetism in semiconductors. Because ferromagnetic spin-spin interactions are mediated by holes in the valence band, changing the Fermi level using co-doping, electric fields, or light can directly manipulate the magnetic ordering. Moreover, engineering the Fermi level position by co-doping makes it possible to modify solubility and self-compensation limits, affecting magnetic characteristics in a number of surprising ways. The Fermi energy can even control the aggregation of magnetic ions, providing a new route to self-organization of magnetic nanostructures in a semiconductor host.

  9. Manufacturing the MFTF magnet

    International Nuclear Information System (INIS)

    The Mirror Fusion Test Facility (MFTF) is a large mirror program experiment for magnetic fusion energy. It will combine and extend the near-classical plasma confinement achieved in 2XIIB with advanced neutral-beam and magnet technologies. The product of ion density and confinement time will be improved more than an order of magnitude, while the superconducting magnet weight will be extrapolated from 15 tons in Baseball II to 375 tons in MFTF. Recent reactor studies show that the MFTF will traverse much of the distance in magnet technology towards the reactor regime

  10. Magnetic flocculation and filtration

    Energy Technology Data Exchange (ETDEWEB)

    Yiacoumi, Sotira; Chin, Ching-Ju; Yin, Tung-Yu [Georgia Inst. of Tech., Atlanta, GA (United States). School of Civil and Environmental Engineering; Tsouris, C., DePaoli, D.W.; Chattin, M.R.; Spurrier, M. [Oak Ridge National Lab., TN (United States)

    1996-10-01

    A model is available in predicting flocculation frequencies between particles of various properties under the influence of a magnetic field. This model provides a basic understanding of fundamental phenomena, such as particle-particle and particle-collector interactions, occurring in HGMF (high gradient magnetic field), and will be extended to describe experimental data of particle flocculation and filtration and predict the performance of high- gradient magnetic filters. It is also expected that this model will eventually lead to a tool for design and optimization of magnetic filters for environmental, metallurgical, biochemical, and other applications.

  11. Biomaterials and magnetism

    Indian Academy of Sciences (India)

    D Bahadur; Jyotsnendu Giri

    2003-06-01

    Magnetism plays an important role in different applications of health care. Magnetite (Fe34) is biocompatible and therefore is one of the most extensively used biomaterials for different applications ranging from cell separation and drug delivery to hyperthermia. Other than this, a large number of magnetic materials in bulk as well as in the form of nano particles have been exploited for a variety of medical applications. In this review, we summarize the salient features of clinical applications, where magnetic biomaterials are used. Magnetic intracellular hyperthermia for cancer therapy is discussed in detail.

  12. Nano-mechanical magnetization reversal

    OpenAIRE

    Kovalev, Alexey A.; Bauer, Gerrit E. W.; Brataas, Arne

    2004-01-01

    The dynamics of the ferromagnetic order parameter in thin magnetic films is strongly affected by the magnetomechanical coupling at certain resonance frequencies. By solving the equation of motion of the coupled mechanical and magnetic degrees of freedom we show that the magnetic-field induced magnetization switching can be strongly accelerated by the lattice and illustrate the possibility of magnetization reversal by mechanical actuation.

  13. Radial Halbach Magnetic Bearings

    Science.gov (United States)

    Eichenberg, Dennis J.; Gallo, Christopher A.; Thompson, William K.

    2009-01-01

    Radial Halbach magnetic bearings have been investigated as part of an effort to develop increasingly reliable noncontact bearings for future high-speed rotary machines that may be used in such applications as aircraft, industrial, and land-vehicle power systems and in some medical and scientific instrumentation systems. Radial Halbach magnetic bearings are based on the same principle as that of axial Halbach magnetic bearings, differing in geometry as the names of these two types of bearings suggest. Both radial and axial Halbach magnetic bearings are passive in the sense that unlike most other magnetic bearings that have been developed in recent years, they effect stable magnetic levitation without need for complex active control. Axial Halbach magnetic bearings were described in Axial Halbach Magnetic Bearings (LEW-18066-1), NASA Tech Briefs, Vol. 32, No. 7 (July 2008), page 85. In the remainder of this article, the description of the principle of operation from the cited prior article is recapitulated and updated to incorporate the present radial geometry. In simplest terms, the basic principle of levitation in an axial or radial Halbach magnetic bearing is that of the repulsive electromagnetic force between (1) a moving permanent magnet and (2) an electric current induced in a stationary electrical conductor by the motion of the magnetic field. An axial or radial Halbach bearing includes multiple permanent magnets arranged in a Halbach array ("Halbach array" is defined below) in a rotor and multiple conductors in the form of wire coils in a stator, all arranged so the rotary motion produces an axial or radial repulsion that is sufficient to levitate the rotor. A basic Halbach array (see Figure 1) consists of a row of permanent magnets, each oriented so that its magnetic field is at a right angle to that of the adjacent magnet, and the right-angle turns are sequenced so as to maximize the magnitude of the magnetic flux density on one side of the row while

  14. Magnetically coupled magnet-spring oscillators

    Energy Technology Data Exchange (ETDEWEB)

    Donoso, G; Ladera, C L; Martin, P [Departamento de Fisica, Universidad Simon BolIvar, Apdo. 89000, Caracas 1086 (Venezuela, Bolivarian Republic of)], E-mail: clladera@usb.ve, E-mail: pmartin@usb.ve

    2010-05-15

    A system of two magnets hung from two vertical springs and oscillating in the hollows of a pair of coils connected in series is a new, interesting and useful example of coupled oscillators. The electromagnetically coupled oscillations of these oscillators are experimentally and theoretically studied. Its coupling is electromagnetic instead of mechanical, and easily adjustable by the experimenter. The coupling of this new coupled oscillator system is determined by the currents that the magnets induce in two coils connected in series, one to each magnet. It is an interesting case of mechanical oscillators with field-driven coupling, instead of mechanical coupling. Moreover, it is both a coupled and a damped oscillating system that lends itself to a detailed study and presentation of many properties and phenomena of such a system of oscillators. A set of experiments that validates the theoretical model of the oscillators is presented and discussed.

  15. Ultrafast magnetization dynamics in diluted magnetic semiconductors

    Energy Technology Data Exchange (ETDEWEB)

    Morandi, O [INRIA Nancy Grand-Est and Institut de Recherche en Mathematiques Avancees, 7 rue Rene Descartes, F-67084 Strasbourg (France); Hervieux, P-A; Manfredi, G [Institut de Physique et Chimie des Materiaux de Strasbourg, 23 rue du Loess, F-67037 Strasbourg (France)], E-mail: morandi@dipmat.univpm.it

    2009-07-15

    We present a dynamical model that successfully explains the observed time evolution of the magnetization in diluted magnetic semiconductor quantum wells after weak laser excitation. Based on the pseudo-fermion formalism and a second-order many-particle expansion of the exact p-d exchange interaction, our approach goes beyond the usual mean-field approximation. It includes both the sub-picosecond demagnetization dynamics and the slower relaxation processes that restore the initial ferromagnetic order in a nanosecond timescale. In agreement with experimental results, our numerical simulations show that, depending on the value of the initial lattice temperature, a subsequent enhancement of the total magnetization may be observed within the timescale of a few hundred picoseconds.

  16. Magnetic microemulsions based on magnetic ionic liquids.

    Science.gov (United States)

    Klee, Andreas; Prevost, Sylvain; Kunz, Werner; Schweins, Ralf; Kiefer, Klaus; Gradzielski, Michael

    2012-11-28

    Microemulsions with magnetic properties were formed by employing a magnetic room temperature ionic liquid (MRTIL) as polar phase, cyclohexane as oil, and an appropriate mixture of ionic surfactant and decanol as a cosurfactant. By means of small-angle neutron scattering (SANS) and electric conductivity the microemulsion structure could be confirmed, where the classical structural sequence of oil-continuous-bicontinuous-polar phase continuous is observed with increasing ratio [polar phase]/[oil]. Accordingly a maximum of the structural size is observed at about equal volumes of oil and MRTIL contained. Therefore this system is structurally the same as normal microemulsions but with the magnetic properties added to it by the incorporation into the systems formulation. PMID:23060241

  17. Magnetic Particle inspection by DC and AC magnetization current

    International Nuclear Information System (INIS)

    Dry magnetic particle inspection was performed to detect the surface defects of the steel billets. The detectability was evaluated according to magnetizing current, temperature, and amount of the magnetic particles on material. We selected a certain set of steel compositions for target materials. Their magnetic properties are measured with B-H hysteresis graph. Results of the magnetic particle inspection(MPI) by direct magnetizing current was compared with results of the finite element method calculations, which were verified by measurement of the magnetic leakage flux above the surface of material. For square rod materials, the magnetic flux density at the corner was about 30% of that at the face center with sufficiently large direct magnetizing current, while it is about 70% with alternating magnetizing current. Alternating magnetizing current generates rather uniform magnetic flux density running from the center to the corner except for the region of about 10 mm extending from the corner.

  18. Science in a Box. Magnets IV: Magnet Earth.

    Science.gov (United States)

    Blizard, Elizabeth B.

    1992-01-01

    Presents low-cost learning activities to help teach elementary students about the earth's magnetic field. One project has students make a model of the earth's magnetic field. Another has them experiment with magnetism. (SM)

  19. Magnetic Properties and Intergranular Action in Bonded Hybrid Magnets

    Institute of Scientific and Technical Information of China (English)

    Hua Zhenghe; Li Shandong; Han Zhida; Wang Dunhui; Zhong Wei; Gu Benxi; Lu Mu; Zhang Jianrong; Du Youwei

    2007-01-01

    Magnetic properties and intergranular action in bonded hybrid magnets, based on NdFeB and strontium ferrite powders were investigated. The long-range magnetostatic interaction and short-range exchange coupling interaction existed simultaneously in bonded hybrid magnets, and neither of them could be neglected. Some magnetic property parameters of hybrid magnets could be approximately obtained by adding the hysteresis loops of two magnets pro rata.

  20. Solid state magnetism

    CERN Document Server

    Crangle, John

    1991-01-01

    Solid state magnetism is important and attempts to understand magnetic properties have led to an increasingly deep insight into the fundamental make up of solids. Both experimental and theoretical research into magnetism continue to be very active, yet there is still much ground to cover before there can be a full understanding. There is a strong interplay between the developments of materials science and of magnetism. Hundreds of new materials have been dis­ covered, often with previously unobserved and puzzling magnetic prop­ erties. A large and growing technology exists that is based on the magnetic properties of materials. Very many devices used in everyday life involve magnetism and new applications are being invented all the time. Under­ standing the fundamental background to the applications is vital to using and developing them. The aim of this book is to provide a simple, up-to-date introduction to the study of solid state magnetism, both intrinsic and technical. It is designed to meet the needs a...