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Sample records for high spin band

  1. High spin rotational bands in 65Zn

    Indian Academy of Sciences (India)

    B Mukherjee; S Muralithar; R P Singh; R Kumar; K Rani; R K Bhowmik

    2001-07-01

    The nucleus $^{65}_{30}$Zn was studied using the 52Cr(16O, 2)65Zn reaction at a beam energy of 65 MeV. The level scheme is extended up to an excitation energy of 10.57 MeV for spin-parity (41/2ħ) with several newly observed transitions placed in it.

  2. High-spin rotational bands in 123I

    DEFF Research Database (Denmark)

    Singh, Purnima; Singh, A.K.; Wilson, A.N.;

    2012-01-01

    High-spin states in I-123 were populated in the reaction Se-80(Ca-48,p4n)I-123 at a beam energy of 207 MeV and gamma-ray coincidence events were measured using the Gammasphere spectrometer. Three weakly populated, high-spin rotational bands have been discovered with characteristics similar to tho...

  3. High-sensitivity Q-band electron spin resonance imaging system with submicron resolution

    Science.gov (United States)

    Shtirberg, Lazar; Twig, Ygal; Dikarov, Ekaterina; Halevy, Revital; Levit, Michael; Blank, Aharon

    2011-04-01

    A pulsed electron spin resonance (ESR) microimaging system operating at the Q-band frequency range is presented. The system includes a pulsed ESR spectrometer, gradient drivers, and a unique high-sensitivity imaging probe. The pulsed gradient drivers are capable of producing peak currents ranging from ˜9 A for short 150 ns pulses up to more than 94 A for long 1400 ns gradient pulses. Under optimal conditions, the imaging probe provides spin sensitivity of ˜1.6 × 108 spins/√Hz or ˜2.7 × 106 spins for 1 h of acquisition. This combination of high gradients and high spin sensitivity enables the acquisition of ESR images with a resolution down to ˜440 nm for a high spin concentration solid sample (˜108 spins/μm3) and ˜6.7 μm for a low spin concentration liquid sample (˜6 × 105 spins/μm3). Potential applications of this system range from the imaging of point defects in crystals and semiconductors to measurements of oxygen concentration in biological samples.

  4. Observation of high-spin bands with large moments of inertia in 124Xe

    Science.gov (United States)

    Nag, Somnath; Singh, A. K.; Hagemann, G. B.; Sletten, G.; Herskind, B.; Døssing, T.; Ragnarsson, I.; Hübel, H.; Bürger, A.; Chmel, S.; Wilson, A. N.; Rogers, J.; Carpenter, M. P.; Janssens, R. V. F.; Khoo, T. L.; Kondev, F. G.; Lauritsen, T.; Zhu, S.; Korichi, A.; Stefanova, E. A.; Fallon, P.; Nyakó, B. M.; Timár, J.; Juhász, K.

    2016-09-01

    High-spin states in 124Xe have been populated using the 80Se(48Ca,4 n ) reaction at a beam energy of 207 MeV and high-multiplicity, γ -ray coincidence events were measured using the Gammasphere spectrometer. Six high-spin bands with large moments of inertia, similar to those observed in neighboring nuclei, have been observed. The experimental results are compared with calculations within the framework of the cranked Nilsson-Strutinsky model. It is suggested that the configurations of the bands involve excitations of protons across the Z =50 shell gap coupled to neutrons within the N =50 -82 shell or excited across the N =82 shell closure.

  5. Triaxial projected shell model description of high-spin band-structures in {sup 103,105}Rh isotopes

    Energy Technology Data Exchange (ETDEWEB)

    Bhat, G.H. [Department of Physics, University of Kashmir, Srinagar 190 006 (India); Sheikh, J.A., E-mail: sjaphysics@gmail.com [Department of Physics, University of Kashmir, Srinagar 190 006 (India); Department of Physics and Astronomy, University of Tennessee, Knoxville, TN 37996 (United States); Dar, W.A. [Department of Physics, University of Kashmir, Srinagar 190 006 (India); Jehangir, S. [Department of Physics, University of Kashmir, Srinagar 190 006 (India); Department of Physics, National Institute of Technology, Srinagar 190 006 (India); Palit, R., E-mail: palit@tifr.res.in [Department of Nuclear and Atomic Physics, Tata Institute of Fundamental Research, Colaba, Mumbai (India); Ganai, P.A. [Department of Physics, University of Kashmir, Srinagar 190 006 (India); Department of Physics, National Institute of Technology, Srinagar 190 006 (India)

    2014-11-10

    High-spin band structures in odd-proton {sup 103,105}Rh are investigated using the microscopic triaxial projected shell model approach. It is demonstrated that the observed band structures built on one- and three-quasiparticle states are reproduced reasonably well in the present work. Further, it is evident from the analysis of the projected wavefunctions that side-band in the low-spin regime is the normal γ-band built on the ground-state configuration. However, in the high-spin regime, the side band is shown to be highly mixed and ceases to be a γ-band. We provide a complete set of electromagnetic transition probabilities for the two bands and the experimental measurements are desirable to test the predictions of the present work.

  6. Systematical study of high-spin rotational bands in neutron-deficient Kr isotopes by the extended projected shell model

    Science.gov (United States)

    Wu, Xin-Yi; Ghorui, S. K.; Wang, Long-Jun; Kaneko, K.; Sun, Yang

    2017-01-01

    We analyze the high-spin structure of the even-even 72-80Kr isotopes using the Projected Shell Model (PSM). With the help of the Pfaffian formulas, we have vigorously extended the quasi-particle (qp) basis of the PSM code and applied in this mass region for the first time. We consider a sufficiently large multi-qp configuration space in order to describe high-spin rotational behavior. The results show that the calculation can reproduce most of the known rotational bands with positive- or negative-parity. Moreover, some side bands appearing in the near-yrast region are predicted. The main structure for each band is discussed in terms of multi-qp configurations. The variations in moment of inertia with spin are explained in terms of successive band crossings among the 2-qp, 4-qp, 6-qp, and 8-qp states. The B (E 2) transition probabilities in these bands are also calculated. To further understand the high-spin behavior of these neutron-deficient nuclei and to confirm predictions of the present work, good high-spin data, especially for B (E 2) transitions, are called for.

  7. Low-lying levels and high-spin band structures in sup 1 sup 0 sup 2 Rh

    CERN Document Server

    Gizon, J; Timar, J; Cata-Danil, G; Nyakó, B M; Zolnai, L; Boston, A J; Joss, D T; Paul, E S; Semple, A T; O'Brien, N J; Parry, C M; Bucurescu, D; Brant, S; Paar, V

    1999-01-01

    Levels in sup 1 sup 0 sup 2 Rh have been populated in the reaction sup 7 sup 0 Zn+ sup 3 sup 6 S at 130 MeV. The level structure of sup 1 sup 0 sup 2 Rh has been investigated using the EUROGAM II array. Low-lying states and four high-spin bands have been identified. The configurations of low-lying levels and two-quasiparticle bands are interpreted in the frame of the interacting boson-fermion-fermion model. The four observed band structures are also compared with cranked shell model calculations using a modified oscillator potential.

  8. High-spin structure of yrast-band in 78Kr

    Indian Academy of Sciences (India)

    P K Joshi; R Palit; H C Jain; S Nagaraj; J A Sheikh

    2001-07-01

    Lifetime of levels up to 22+, have been measured in 78Kr and an oblate shape is assigned to the ground state using the CSM and the configuration dependent shell correction calculations. Calculations further show that 78Kr is highly -soft nucleus. The experimental t values coupled with theoretical calculations indicate an oblate shape for 78Kr at low spins and triaxial shape at higher spins

  9. Band head spin assignment of Tl isotopes of superdeformed rotational bands

    Science.gov (United States)

    Goel, Alpana; Nair, Uma; Yadav, Archana

    2014-09-01

    The Variable Moment of Inertia (VMI) model is proposed for the assignment of band head spin of super deformed (SD) rotational bands, which in turn is helpful in the spin prediction of SD bands. The moment of inertia and stiffness parameter (C), were calculated by fitting the proposed transition energies. The calculated transition energies are highly dependent on the prescribed spins. The calculated and observed transition energies agree well when an accurate band head spin (I 0) is assigned. The results are in good agreement with other theoretical results reported in literature. In this paper, we have reported the band head spin value 16 rotational band of super deformed Tl isotopes.

  10. W-band EPR studies of high-spin nitrenes with large spin-orbit contribution to zero-field splitting

    Science.gov (United States)

    Akimov, Alexander; Masitov, Artem; Korchagin, Denis; Chapyshev, Sergei; Misochko, Eugenii; Savitsky, Anton

    2015-08-01

    First W-band 94 GHz EPR spectra of randomly oriented triplet, quintet, and septet nitrenes formed during the photolysis of 1,3,5-triazido-2,4,6-tribromobenzene in cryogenic matrices are reported. In comparison with conventional X-band 9 GHz electron paramagnetic resonance (EPR) spectroscopy, W-band EPR spectroscopy allows the detection and complete spectroscopic characterization of all paramagnetic species formed at different stages of the photolysis of aromatic polyazides. This type of spectroscopy is of paramount importance for experimental determination of the sign of the zero-field splitting (ZFS) parameters of high-spin molecules with large spin-orbit contribution to the ZFS, caused by the effect of heavy atoms. The study shows that triplet 1,3-diazido-2,4,6-tribromo-5-nitrenobenzene (T1) has DT = 1.369 cm-1, ET = 0.093 cm-1, and g = 2.0033, quintet 1-azido-2,4,6-tribromo-3,5-dinitrenobenzene (Q1) shows DQ = - 0.306 cm-1, EQ = 0.0137 cm-1, and g = 2.0070, and septet 2,4,6-tribromo-1,3,5-trinitrenobenzene (S1) has DS = - 0.203 cm-1, ES = 0, and g = 2.0073. The experimental ZFS parameters agree well with the results of density functional theory calculations at the PBE/Ahlrichs-DZ level of theory, showing that such calculations adequately describe the magnetic properties of bromine-containing high-spin nitrenes. Both experimental and theoretical data indicate that, in contrast to all known to date quintet dinitrenes, dinitrene Q1 has the negative sign of magnetic anisotropy due to the "heavy atom effect." This dinitrene along with septet trinitrene S1 possess the largest negative value of D among all known quintet and septet organic polyradicals.

  11. High-spin Band Structure in Odd-odd 170Re

    Institute of Scientific and Technical Information of China (English)

    WangHualei; ZhangYuhu; ZhouXiaohong; GuoYingxiang; LeiXiangguo; LiuMinliang; LuoPeng; XieChengying; SongLitao; YuHaiping; ZhengYong; GuoWentao; WenShuxian; ZhuLihua

    2003-01-01

    High-spin states in doubly odd 170Re nucleus have been investigated for the first time, through in-beam γ-ray spectroscopy, following the 142Nd(32S, 1p3n γ) 170Re reaction at 166 McV bombarding energy. The 32 Sbeam was provided by the tandem accelerator at the China Institute of Atomic Energy, Bcijing. The 142 Ndtarget is an enriched metallic foil of about 2.2 mg/cm2 thickness with a 7.0 mg/cm2 Pb backing to stop the recoiling nuclei. Measurement of X-γ, and γ-γ coincidences wcrc performed with 12 BGO(AC)HPGc detectors. A total of 150 million coincidence events wcrc recorded. The detector energies and cfficicncics wcrc calibrated

  12. W-band EPR studies of high-spin nitrenes with large spin-orbit contribution to zero-field splitting

    Energy Technology Data Exchange (ETDEWEB)

    Akimov, Alexander; Masitov, Artem; Korchagin, Denis; Chapyshev, Sergei; Misochko, Eugenii, E-mail: misochko@icp.ac.ru [Institute of Problems of Chemical Physics RAS, Chernogolovka (Russian Federation); Savitsky, Anton [Max-Planck Institute for Chemical Energy Conversion, Mulheim/Ruhr (Germany)

    2015-08-28

    First W-band 94 GHz EPR spectra of randomly oriented triplet, quintet, and septet nitrenes formed during the photolysis of 1,3,5-triazido-2,4,6-tribromobenzene in cryogenic matrices are reported. In comparison with conventional X-band 9 GHz electron paramagnetic resonance (EPR) spectroscopy, W-band EPR spectroscopy allows the detection and complete spectroscopic characterization of all paramagnetic species formed at different stages of the photolysis of aromatic polyazides. This type of spectroscopy is of paramount importance for experimental determination of the sign of the zero-field splitting (ZFS) parameters of high-spin molecules with large spin-orbit contribution to the ZFS, caused by the effect of heavy atoms. The study shows that triplet 1,3-diazido-2,4,6-tribromo-5-nitrenobenzene (T1) has D{sub T} = 1.369 cm{sup −1}, E{sub T} = 0.093 cm{sup −1}, and g = 2.0033, quintet 1-azido-2,4,6-tribromo-3,5-dinitrenobenzene (Q1) shows D{sub Q} = − 0.306 cm{sup −1}, E{sub Q} = 0.0137 cm{sup −1}, and g = 2.0070, and septet 2,4,6-tribromo-1,3,5-trinitrenobenzene (S1) has D{sub S} = − 0.203 cm{sup −1}, E{sub S} = 0, and g = 2.0073. The experimental ZFS parameters agree well with the results of density functional theory calculations at the PBE/Ahlrichs-DZ level of theory, showing that such calculations adequately describe the magnetic properties of bromine-containing high-spin nitrenes. Both experimental and theoretical data indicate that, in contrast to all known to date quintet dinitrenes, dinitrene Q1 has the negative sign of magnetic anisotropy due to the “heavy atom effect.” This dinitrene along with septet trinitrene S1 possess the largest negative value of D among all known quintet and septet organic polyradicals.

  13. Semiclassical spin transport in spin-orbit-coupled bands.

    Science.gov (United States)

    Culcer, Dimitrie; Sinova, Jairo; Sinitsyn, N A; Jungwirth, T; MacDonald, A H; Niu, Q

    2004-07-23

    Motivated by recent interest in novel spintronics effects, we develop a semiclassical theory of spin transport that is valid for spin-orbit coupled bands. Aside from the obvious convective term in which the average spin is transported at the wave packet group velocity, the spin current has additional contributions from the wave packet's spin and torque dipole moments. Electric field corrections to the group velocity and carrier spin contribute to the convective term. Summing all terms we obtain an expression for the intrinsic spin-Hall conductivity of a hole-doped semiconductor, which agrees with the Kubo formula prediction for the same quantity. We discuss the calculation of spin accumulation, which illustrates the importance of the torque dipole near the boundary of the system.

  14. Band head spin assignment of superdeformed bands in 86Zr

    Science.gov (United States)

    Dadwal, Anshul; Mittal, H. M.

    2016-11-01

    Two parameter expressions for rotational spectra viz. variable moment of inertia (VMI), ab formula and three parameter Harris ω 2 expansion are used to assign the band head spins (I 0) of four rotational superdeformed bands in 86Zr. The least-squares fitting method is employed to obtain the band head spins of these four bands in the A ∼ 80 mass region. Model parameters are extracted by fitting of intraband γ-ray energies, so as to obtain a minimum root-mean-square (rms) deviation between the calculated and the observed transition energies. The calculated transition energies are found to depend sensitively on the assigned spins. Whenever an accurate band head spin is assigned, the calculated transition energies are in agreement with the experimental transition energies. The dynamic moment of inertia is also extracted and its variation with rotational frequency is investigated. Since a better agreement of band head spin with experimental results is found using the VMI model, it is a more powerful tool than the ab formula and Harris ω 2 expansion.

  15. Influence of band interaction on the spin prediction of superdeformed rotational bands

    Science.gov (United States)

    Liu, S. X.; Xin, X. B.; Lei, Y. A.; Zeng, J. Y.

    2000-01-01

    The influence of band interaction on the spin predictions and the J (2) pattern of superdeformed (SD) bands are investigated. To make a reliable spin prediction using the best-fit method, the transitions with significant band mixing should be excluded from the least-squares fitting. Spin predictions for 15 SD bands in the A ~150 region are made. In particular, the spin of the lowest level of the first discovered high-spin SD band 152 Dy(1) is predicted to be I 0 = 26. A two-band mixing model is used to describe the irregular behaviour of J (2) with angular momentum. Two types of J (2) patterns are discussed. For the band-crossing case, the J (2) pattern in the band-crossing region is of a V (or inverse-V) type, which has been observed in both the A ~190 and 150 regions. For the band-mixing case characterized by a relatively weak band interaction, the J (2) pattern in the band-mixing region is of a W (or inverse-W) type, which was observed only in some SD bands in the A ~150 region.

  16. Topological flat bands from dipolar spin systems.

    Science.gov (United States)

    Yao, N Y; Laumann, C R; Gorshkov, A V; Bennett, S D; Demler, E; Zoller, P; Lukin, M D

    2012-12-28

    We propose and analyze a physical system that naturally admits two-dimensional topological nearly flat bands. Our approach utilizes an array of three-level dipoles (effective S=1 spins) driven by inhomogeneous electromagnetic fields. The dipolar interactions produce arbitrary uniform background gauge fields for an effective collection of conserved hard-core bosons, namely, the dressed spin flips. These gauge fields result in topological band structures, whose band gap can be larger than the corresponding bandwidth. Exact diagonalization of the full interacting Hamiltonian at half-filling reveals the existence of superfluid, crystalline, and supersolid phases. An experimental realization using either ultracold polar molecules or spins in the solid state is considered.

  17. Study of octupole-deformed K=1/2 bands in sup 2 sup 2 sup 7 Th High spin states

    CERN Document Server

    Hammond, N

    2002-01-01

    High spin states in sup 2 sup 2 sup 7 Th have been populated using the reaction sup 2 sup 2 sup 6 Ra(alpha,3n) sup 2 sup 2 sup 7 Th at a bombarding energy of 33 MeV. The high-spin rotational structures of this nucleus have been refined and extended. In addition, the linking of these structures with the low-spin states known from sup 2 sup 3 sup 1 U alpha decay has allowed a comprehensive decay scheme of this nucleus to be assembled for the first time. Four previously known rotational bands are interpreted as Coriolis-coupled K suppi = 1/2 sup + and K suppi = 1/2 sup - bands, in agreement with predictions using a reflection-asymmetric mean-field approach. The determination of decoupling parameters for these bands is consistent with the a(K suppi = 1/2 sup +) = -a(K suppi = 1/2 sup -) rigid-octupole-rotor expectation. A further rotational band is interpreted as having K suppi = 3/ sup - . Measured D sub 0 /Q sub 0 ratios are consistent with an interpolation, of the values given for neighbouring even-even nuclei...

  18. Spin alignment in superdeformed rotational bands

    Energy Technology Data Exchange (ETDEWEB)

    Stephens, F.S. (Lawrence Berkeley Lab., CA (USA). Nuclear Science Div.)

    1990-12-24

    Many superdeformed bands in different nuclei are found to have virtually identical moments of inertia and alignments that differ from each other by quantized amounts - multiples of 1/2 {Dirac h}. Pseudo spins represent the only source of quantized alignment that has been thought of to date. Additional puzzles in these bands are the absence of other larger effects on the moments of inertia, and a surprising number of alignments of 1 {Dirac h}. (orig.).

  19. Rotational bands terminating at maximal spin in the valence space

    Energy Technology Data Exchange (ETDEWEB)

    Ragnarsson, I.; Afanasjev, A.V. [Lund Institute of Technology (Sweden)

    1996-12-31

    For nuclei with mass A {le} 120, the spin available in {open_quotes}normal deformation configurations{close_quotes} is experimentally accessible with present detector systems. Of special interest are the nuclei which show collective features at low or medium-high spin and where the corresponding rotational bands with increasing spin can be followed in a continuous way to or close to a non-collective terminating state. Some specific features in this context are discussed for nuclei in the A = 80 region and for {sup 117,118}Xe.

  20. Pairing Correlations at High Spins

    Science.gov (United States)

    Ma, Hai-Liang; Dong, Bao-Guo; Zhang, Yan; Fan, Ping; Yuan, Da-Qing; Zhu, Shen-Yun; Zhang, Huan-Qiao; Petrache, C. M.; Ragnarsson, I.; Carlsson, B. G.

    The pairing correcting energies at high spins in 161Lu and 138Nd are studied by comparing the results of the cranked-Nilsson-Strutinsky (CNS) and cranked-Nilsson-Strutinsky-Bogoliubov (CNSB) models. It is concluded that the Coriolis effect rather than the rotational alignment effect plays a major role in the reduction of the pairing correlations in the high spin region. Then we proposed an average pairing correction method which not only better reproduces the experimental data comparing with the CNS model but also enables a clean-cut tracing of the configurations thus the full-spin-range discussion on the various rotating bands.

  1. Zero-magnetic-field spin-splitting and the warping in the valence band of highly p-doped asymmetric AlGaAs/GaAs quantum wells

    Energy Technology Data Exchange (ETDEWEB)

    Hirmer, Michael; Hirmer, M.; Schuh, D.; Wegscheider, W.; Korn, T.; Schueller, C. [Institut fuer Experimentelle Physik, Universitaet Regensburg, 93040 Regensburg (Germany)

    2011-07-01

    Zero-Magnetic-Field-Spin-Splitting (ZMFSS) in 2D quantum wells (QW) induced by the structure inversion asymmetry, and its control, are of major importance for both fundamental research and spintronic applications. In hole systems, the asymmetry leads to a ZMFSS of the heavy hole (HH) states in third order of the in-plane wave vector k. In our experiments, we focus on highly p-doped asymmetric AlGaAs/GaAs QW. We utilize electronic intersubband Raman measurements in backscattering geometry. In all samples we observe a low-energy spin-density excitation (SDE) with energies in the range of 0-3 meV. Samples with higher hole density show a two-component SDE. Comparing these excitation energies to 8 band k.p calculations of the valence subbands, the SDE can be interpreted as an intersubband excitation of the spin-split HH ground state, reflecting directly the ZMFSS. The two components can be attributed to different HH dispersions in different crystallographic directions, the so-called warping. We found that the observed spin splitting increases systematically with increasing hole density p, or by an external electric field. Measurements of the Shubnikov de Haas oscillations showed similar results.

  2. Magnetic properties of weakly exchange-coupled high spin Co(II) ions in pseudooctahedral coordination evaluated by single crystal X-band EPR spectroscopy and magnetic measurements.

    Science.gov (United States)

    Neuman, Nicolás I; Winkler, Elín; Peña, Octavio; Passeggi, Mario C G; Rizzi, Alberto C; Brondino, Carlos D

    2014-03-01

    We report single-crystal X-band EPR and magnetic measurements of the coordination polymer catena-(trans-(μ2-fumarato)tetraaquacobalt(II)), 1, and the Co(II)-doped Zn(II) analogue, 2, in different Zn:Co ratios. 1 presents two magnetically inequivalent high spin S = 3/2 Co(II) ions per unit cell, named A and B, in a distorted octahedral environment coordinated to four water oxygen atoms and trans coordinated to two carboxylic oxygen atoms from the fumarate anions, in which the Co(II) ions are linked by hydrogen bonds and fumarate molecules. Magnetic susceptibility and magnetization measurements of 1 indicate weak antiferromagnetic exchange interactions between the S = 3/2 spins of the Co(II) ions in the crystal lattice. Oriented single crystal EPR experiments of 1 and 2 were used to evaluate the molecular g-tensor and the different exchange coupling constants between the Co(II) ions, assuming an effective spin S′= 1/2. Unexpectedly, the eigenvectors of the molecular g-tensor were not lying along any preferential bond direction, indicating that, in high spin Co(II) ions in roughly octahedral geometry with approximately axial EPR signals, the presence of molecular pseudo axes in the metal site does not determine preferential directions for the molecular g-tensor. The EPR experiment and magnetic measurements, together with a theoretical analysis relating the coupling constants obtained from both techniques, allowed us to evaluate selectively the exchange coupling constant associated with hydrogen bonds that connect magnetically inequivalent Co(II) ions (|JAB(1/2)| = 0.055(2) cm(–1)) and the exchange coupling constant associated with a fumarate bridge connecting equivalent Co(II) ions (|JAA(1/2)| ≈ 0.25 (1) cm(–1)), in good agreement with the average J(3/2) value determined from magnetic measurements.

  3. Spins of Triaxial Superdeformed Bands in 86Zr

    Institute of Scientific and Technical Information of China (English)

    LIU Zu-Hua; YANG Chun-Xiang

    2000-01-01

    Transition energies of three triaxial superdeformed bands in 86Zr were fitted by the power-series expansion of spin I in odd powers of rotationalfrequeney ψ and by the two-parameter expression for rotational spectra. Level spins of these bands were assigned by means of the least-squares fits

  4. Spins of superdeformed rotational bands in Tl isotopes

    Energy Technology Data Exchange (ETDEWEB)

    Dadwal, Anshul; Mittal, H.M. [Dr. B.R. Ambedkar National Institute of Technology, Jalandhar (India)

    2017-01-15

    The two-parameter model defined for even-even nuclei viz. soft-rotor formula is used to assign the band-head spin of the 17 rotational bands in Tl isotopes. The least-squares fitting method is employed to obtain the spins of these bands in the A ∝ 190 mass region. The calculated transition energies are found to depend sensitively on the proposed spin. Whenever a correct spin assignment is made, the calculated and experimental transition energies coincide very well. The dynamic moment of inertia is also calculated and its variation with rotational frequency is explored. (orig.)

  5. Spins of superdeformed rotational bands in Tl isotopes

    Science.gov (United States)

    Dadwal, Anshul; Mittal, H. M.

    2017-01-01

    The two-parameter model defined for even-even nuclei viz. soft-rotor formula is used to assign the band-head spin of the 17 rotational bands in Tl isotopes. The least-squares fitting method is employed to obtain the spins of these bands in the A˜ 190 mass region. The calculated transition energies are found to depend sensitively on the proposed spin. Whenever a correct spin assignment is made, the calculated and experimental transition energies coincide very well. The dynamic moment of inertia is also calculated and its variation with rotational frequency is explored.

  6. Spins of superdeformed band in {sup 192}Hg

    Energy Technology Data Exchange (ETDEWEB)

    Lauritsen, T.; Khoo, T.L.; Henry, R.G. [and others

    1995-08-01

    Determination of the spins of SD states is the most important challenge in the study of superdeformation. Knowledge of the spin will provide crucial information on SD bands, in particular on the fascinating phenomenon of bands with identical energies and moments of inertia. Angular distribution coefficients of the {gamma}rays decaying out of the {sup 192}Hg SD band were determined using Eurogam data. These coefficients, as well as the spectral shape and multiplicity of the spectrum, are compared with the results of calculations, thereby providing a check on these calculations. From the measured decay multiplicity and the calculated average spin removed per photon (0.3 h), we deduce the average spin {bar I}{sub decay} removed by the {gamma} rays connecting SD and normal states. The spin I{sub SD} of the SD band from which the decay occurs is given by I{sub SD} = {bar I} decay + {bar I} ND, where {bar I} ND is the average spin removed by the normal yrast states. The state from which the major decay out of the SD band occurs is found to have spin 9.5 {plus_minus} 0.8 h. Since angular momentum is (quantized), this leads to a spin assignment of 9 or 10 h. The latter value is favored since the yrast band in the SD well must have only even spin values. This constitutes the first deduction of spin from data in the mass 150 and 190 regions. The spin of 10 h agrees with the spin which is inferred from a model, using the observed moment of inertia (Im){sup (2)}{omega}.

  7. Transition from spin accumulation into interface states to spin injection in silicon and germanium conduction bands

    Science.gov (United States)

    Jain, Abhinav; Rojas-Sanchez, Juan-Carlos; Cubukcu, Murat; Peiro, Julian; Le Breton, Jean-Christophe; Vergnaud, Céline; Augendre, Emmanuel; Vila, Laurent; Attané, Jean-Philippe; Gambarelli, Serge; Jaffrès, Henri; George, Jean-Marie; Jamet, Matthieu

    2013-04-01

    Electrical spin injection into semiconductors paves the way for exploring new phenomena in the area of spin physics and new generations of spintronic devices. However the exact role of interface states in the electrical spin injection mechanism from a magnetic tunnel junction into a semiconductor is still under debate. Here we demonstrate a clear transition from spin accumulation into interface states to spin injection in the conduction band of n-Si and n-Ge using a CoFeB/MgO tunnel contact. We observe spin signal amplification at low temperature due to spin accumulation into interface states followed by a clear transition towards spin injection in the conduction band from approximately 150 K up to room temperature. In this regime, the spin signal is reduced down to a value compatible with the standard spin diffusion model. More interestingly, in the case of germanium, we demonstrate a significant modulation of the spin signal by applying a back-gate voltage to the conduction channel. We also observe the inverse spin Hall effect in Ge by spin pumping from the CoFeB electrode. Both observations are consistent with spin accumulation in the Ge conduction band.

  8. New Method for Spin Assignment of Superdeformed Rotational Bands

    Institute of Scientific and Technical Information of China (English)

    MU Liang-Zhu; WU Chong-Shi

    2005-01-01

    A new method for spin assignment of superdeformed rotational bands is proposed and it turns out to be more efficient than other methods used before. The application is made to superdeformed bands in A ~ 190 and A ~ 150 mass regions. By analyzing the standard deviation of the fixed γ-ray energies of an SD band in different methods,the advantage of the present method over the other methods is presented. This method brings then a comprehensive interpretation of the methods used in spin assignment.

  9. New Method for Spin Assignment of Superdeformed Rotational Bands

    Science.gov (United States)

    Mu, Liang-Zhu; Wu, Chong-Shi

    2005-04-01

    A new method for spin assignment of superdeformed rotational bands is proposed and it turns out to be more efficient than other methods used before. The application is made to superdeformed bands in A~190 and A~150 mass regions. By analyzing the standard deviation of the fixed γ-ray energies of an SD band in different methods, the advantage of the present method over the other methods is presented. This method brings then a comprehensive interpretation of the methods used in spin assignment.

  10. High Spin States in 106Ag

    Institute of Scientific and Technical Information of China (English)

    ZHULi-hua; HEChuang-ye; WUXiao-guang; WANGZhi-min; WENShu-xian; LIGuang-sheng; ZHANGZhen-long; CUIXing-zhu; MENGRui; MARui-gang; YANGChun-xiang; M.M.Ndontchueng

    2003-01-01

    Nuclei in A≈110 exhibit a variety of fascinating phenomena at high spin states, such as single particle v.s. collective excitation, shape coexistence and transition, magnetic rotation, and especially the chiral doublet bands which originally predicted by theoretical calculation and recently observed in experiment.

  11. Ultrafast Band Engineering and Transient Spin Currents in Antiferromagnetic Oxides.

    Science.gov (United States)

    Gu, Mingqiang; Rondinelli, James M

    2016-04-29

    We report a dynamic structure and band engineering strategy with experimental protocols to induce indirect-to-direct band gap transitions and coherently oscillating pure spin-currents in three-dimensional antiferromagnets (AFM) using selective phononic excitations. In the Mott insulator LaTiO3, we show that a photo-induced nonequilibrium phonon mode amplitude destroys the spin and orbitally degenerate ground state, reduces the band gap by 160 meV and renormalizes the carrier masses. The time scale of this process is a few hundreds of femtoseconds. Then in the hole-doped correlated metallic titanate, we show how pure spin-currents can be achieved to yield spin-polarizations exceeding those observed in classic semiconductors. Last, we demonstrate the generality of the approach by applying it to the non-orbitally degenerate AFM CaMnO3. These results advance our understanding of electron-lattice interactions in structures out-of-equilibrium and establish a rational framework for designing dynamic phases that may be exploited in ultrafast optoelectronic and optospintronic devices.

  12. Properties of rotational bands at the spin limit in A {approximately} 50, A {approximately} 65 and A {approximately} 110 nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Janzen, V.P.; Andrews, H.R.; Ball, G.C. [Chalk River Labs., Ontario (Canada)] [and others

    1996-12-31

    There is now widespread evidence for the smooth termination of rotational bands in A {approx_equal} 110 nuclei at spins of 40-to-50{Dirac_h}s. The characteristics of these bands are compared to those of bands recently observed to high spin in {sup 64}Zn and {sup 48}Cr, studied with the 8{pi} {gamma}-ray spectrometer coupled to the Chalk River miniball charged-particle-detector array.

  13. Systematics of even-even T{sub z}= 1 nuclei in the A= 80 region: High-spin rotational bands in {sup 74}Kr, {sup 78}Sr, and {sup 82}Zr

    Energy Technology Data Exchange (ETDEWEB)

    Rudolph, D.; Baktash, C.; Gross, C.J.; Jin, H.; Yu, C.H. [Physics Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States); Rudolph, D. [Sektion Physik der Ludwig-Maximilians-Universitaet Muenchen, D-85748 Garching (Germany); Gross, C.J. [Oak Ridge Institute for Science and Education, Oak Ridge, Tennessee 37831 (United States); Satula, W. [Department of Physics, University of Tennessee, Knoxville, Tennessee 37996 (United States); Satula, W. [Joint Institute for Heavy Ion Research, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States); Satula, W. [Institute of Theoretical Physics, Warsaw University, PL-00681 Warsaw (Poland); Wyss, R. [The Royal Institute of Technology, Physics Department Frescati, S-104 05 Stockholm (Sweden); Birriel, I.; Saladin, J.X.; Winchell, D.F.; Wood, V.Q. [Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, Pennsylvania 15260 (United States); Devlin, M.; LaFosse, D.R.; Lerma, F.; Sarantites, D.G. [Chemistry Department, Washington University, St. Louis, Missouri 63130 (United States); Sylvan, G.N.; Tabor, S.L. [Department of Physics, Florida State University, Tallahassee, Florida 32306 (United States)

    1997-07-01

    High-spin states of T{sub z}=1 nuclei were studied with the reactions {sup 58}Ni({sup 28}Si,3{alpha}){sup 74}Kr, {sup 58}Ni({sup 28}Si,2{alpha}){sup 78}Sr, and {sup 58}Ni({sup 28}Si,2p2n){sup 82}Zr at 130 MeV beam energy. The Gammasphere array in conjunction with the 4{pi} charged-particle detector array Microball was used to detect {gamma} rays in coincidence with evaporated light charged particles. The known {pi}=+, {alpha}=0 yrast bands were extended to I=28{h_bar} at 20 MeV excitation energy. For all three nuclei, a number of positive- and negative-parity sidebands were established; altogether 15 new rotational bands were found. The data are discussed using the pairing-and-deformation self-consistent total Routhian surface (TRS) model: High-spin structures of {sup 74}Kr and {sup 78}Sr are governed by the shell gaps at large prolate deformation while {sup 82}Zr seems to exhibit shape coexistence. Nearly identical bands were established which may be explained as arising from the fp orbits acting as spectators at very elongated shapes. The experimental data in these T{sub z}=1 nuclei are in good agreement with predictions of the TRS model using conventional T=1 like-nucleon pairing correlations. {copyright} {ital 1997} {ital The American Physical Society}

  14. Experimental and theoretical investigation of the vibrational band structure of the 1 u5Π -1 g5Π high-spin system of C2

    Science.gov (United States)

    Bornhauser, P.; Visser, B.; Beck, M.; Knopp, G.; van Bokhoven, J. A.; Marquardt, R.; Radi, P. P.

    2017-03-01

    Vibrational levels of the recently observed high-spin transition (1 u5Π -1 g5Π ) of dicarbon [P. Bornhauser et al., J. Chem. Phys. 142, 094313 (2015)] are explored by applying non-linear double-resonant four-wave mixing and laser-induced fluorescence methods. The deperturbation of the d g3Π , υ = 8 and 1 g5Π , υ = 3 states results in accurate molecular constants for the υ = 3 "dark" quintet state. In addition, the spin-orbit interaction constant is determined and parameters for the upper Swan level d g3Π , υ = 8 are improved. The first excited vibrational state of 1 u5Π is observed by performing perturbation-assisted intersystem crossing via "gateway" states in the d g3Π , υ = 6 ˜1 g5Π ,υ = 0 system. The rotationally resolved spectra yield 11 transitions to 1 u5Π , υ = 1 that include four spin-substates. Data reduction results in accurate molecular constants of this vibrational level in the shallow potential energy surface of this state. Finally, υ = 1 and 2 of the lower quintet state (1 g5Π ) are measured by performing perturbation-assisted double-resonant excitation to the 1 u5Π , υ = 0 state and observing dispersed fluorescence. The obtained molecular constants are compared with high level ab initio computations at the multi-reference configuration interaction (MRCI) level of theory by using a large correlation consistent basis set or, alternatively, by applying the computationally less demanding method of explicitly correlated multi-reference configuration interaction (MRCI-F12). The spectroscopic accuracy of both methods is evaluated by comparison with the experimental findings.

  15. An investigation of pairing correlations in diabatic configurations at high spin and large deformation applications to the description of SD bands in sup 1 sup 4 sup 3 Eu

    CERN Document Server

    Axelsson, A; Nyberg, J

    2002-01-01

    The HFB cranked shell model is applied in an investigation of the selfconsistent pairing properties of the superdeformed (SD) bands in sup 1 sup 4 sup 3 Eu. Results from a fully pairing and deformation selfconsistent mesh calculation of the properties of the most intense SD band in sup 1 sup 4 sup 3 Eu are presented, as well as pairing selfconsistent calculations done at a fixed deformation close to the SD minimum for an excited SD configuration. The calculations are compared to unpaired calculations and to published experimental data. Fully diabatic configurations are studied and total energy surfaces are constructed for fixed values of the angular momentum. Other issues addressed include the development of the particle number distribution in the HFB wave function up to very high frequency, the consequences of using a fixed Fermi energy in high-spin calculations and the effects of the number of excited quasiparticles on the pairing properties of the superdeformed nucleus.

  16. Pseudo-spin band in the odd-odd nucleus sup 1 sup 7 sup 2 Lu

    CERN Document Server

    Venkova, T; Gast, W; Podsvirova, E O; Jäger, H M; Mihailescu, L; Bazzacco, D; Menegazzo, R; Lunardi, S; Alvarez, C R; Ur, C; Martínez, T; Angelis, G D; Axiotis, M; Napoli, D; Urban, W; Rzaca-Urban, T; Frauendorf, S

    2003-01-01

    High-spin states in the odd-odd nucleus sup 1 sup 7 sup 2 Lu have been populated in a sup 1 sup 7 sup 0 Er( sup 7 Li,5n) reaction and the emitted gamma-radiation was detected with the GASP array. Two sequences of a new identical band have been observed with the transition energies in the favoured and unfavoured sequences being identical within approx 3 keV at low spins and approx 1 keV at high spins over the whole observed spin range. An interpretation as a pseudo-spin singlet band of pi 1/2 sup - [541] x nu 1/2 sup - [420] configuration is proposed. It represents the best example of a pseudo-spin singlet band in normal deformed nuclei known until now.

  17. High frequency band crossings in ^168Lu.

    Science.gov (United States)

    Roux, D. G.; Li, Y.; Ma, W. C.; Amro, H.; Thompson, J.; Winger, J.; Hagemann, G.; Herskind, B.; Jensen, D.; Sletten, G.; Wilson, J.; Fallon, P.; Diamond, R.; Goergen, A.; Machiavelli, A.; Ward, D.; Hübel, H.; Domscheit, J.

    2003-10-01

    High spin states in ^168Lu were populated using the ^123Sb(^48Ca,3n) reaction at 203 MeV. The beam was provided by the 88" cyclotron at LBNL, and coincident gamma rays were detected with the Gammasphere spectrometer array. An analysis of the data which had been sorted into three- and four- dimensional histograms confirmed the four previously known (J.H.Ha et al. J. Phys. Soc. Japan 71 (2002) 1663-1671) pairs of signature partner bands and extended them to considerably higher spins (in one case up to a tentative 50 hbar). In addition, a new pair of signature partners, as well as a new doubly decoupled band were found. On the basis of the present data, the configuration of one of the known bands, previously assigned π d_3/2 øtimes ν i_13/2 was reassigned as π d_5/2 øtimes ν i_13/2. High frequency band crossings, beyond the first ν i_13/2 alignment, were observed for the first time. These results will be discussed with reference to Cranking Shell Model calculations.

  18. High-spin and low-spin states in Invar and related alloys

    Science.gov (United States)

    Moruzzi, V. L.

    1990-04-01

    Total-energy band calculations that show the coexistence of a high-spin and low-spin state in fcc transition metals and alloys are presented. The energy difference between the two states is shown to be a function of the electron concentration and to vanish at 8.6. At larger electron concentrations the low-temperature state is the high-spin state, and the thermal expansion is shown to pause at a system-dependent characteristic temperature. At lower electron concentrations the low-temperature state is the low-spin state, and enhanced thermal expansion is expected. An analysis that leads to a qualitative understanding of the thermal properties of Invar and that implies a connection with martensitic transformations and spin glasses in related alloys is presented. For Invar a magnetic collapse from the high-spin to the low-spin state at a pressure of 55 kbar is predicted.

  19. High Spin Structure in 106Pd

    Institute of Scientific and Technical Information of China (English)

    于蓓蓓; 竺礼华; 贺创业; 吴晓光; 郑云; 李广生; 王烈林; 姚顺和; 张彪; 徐川; 郝昕; 王建国; 顾龙; 张明

    2012-01-01

    The high spin states of 106pd have been populated through the 100Mo(11B, lp4n)106Pd reaction using a beam energy of 60 MeV provided by the Beijing HI-13 tandem accel- erator at China Institute of Atomic Energy. By analyzing the V-3' coincidence relation and DCO raios of transitions, 3 rotational bands with 13 new states and 22 new 7 transitions belonging to 106pd were constructed. Bands 2 and 3 with negative parity were supposed to build on the vh1l/297/2 and vh11/2ds/2 configuration, respectively.

  20. High-spin states populated in deep-inelastic reactions

    Energy Technology Data Exchange (ETDEWEB)

    Mohammadi, S. [University of Surrey, Guildford (United Kingdom). Dept. of Physics; University of Payam-Noor (Iran, Islamic Republic of). Dept. of Physics; Podolyak, Zs.; Gelletly, W.; Longdown, S.; Regan, P.H.; Valiente Dobon, J.-J.; Walker, P.M. [University of Surrey, Guildford (United Kingdom). Dept. of Physics; Angelis, G. de; Axiotis, M.; Farnea, E.; Gadea, A.; Kroell, Th.; Marginean, N.; Zhang, Y.H.; Martinez, T. [Istituto Nazionali di Fisica Nucleare, Legnaro (Italy). Laboratori Nazionali di Legnaro; Bazzacco, D.; Brandolini, F.; Lunardi, S.; Ur, C.A. [Istituto Nazionali di Fisica Nucleare, Padova (Italy). Dipt. di Fisica; Bizzeti, P.G. [Istituto Nazionali di Fisica Nucleare, Firenze (Italy). Dipt. di Fisica; Broda, R. [Niewodniczanski Institute of Nuclear Physics, Krakow (Poland); Bucurescu, D.; Ionescu-Bujor, M.; Iordachescu, A. [Institute of Physics and Nuclear Engineering, Bucharest (Romania); Medina, N.H. [Sao Paulo Univ., SP (Brazil). Inst. de Fisica. Lab. Pelletron; Quintana, B. [University of Salamanca (Spain); Rubio, B. [Instituto di Fisica Corpuscular, Valencia (Spain)

    2004-09-15

    High spin states in the neutron rich {sup 188}Os and {sup 190}Os nuclei have been populated using the {sup 82}Se + {sup 192}Os deep-inelastic reaction. The level schemes are extended up to spin I {approx_equal}21. The observed new structures are tentatively interpreted as fragments of rotational bands built on multi-quasiparticle configurations. (author)

  1. High-spin states in 75Kr

    Science.gov (United States)

    Chishti, A. A.; Gelletly, W.; Lister, C. J.; Mcneill, J. H.; Varley, B. J.; Love, D. J. G.; Skeppstedt, O.

    1989-09-01

    Levels in the 75Kr nucleus were populated in the inverse 24Mg( 54Fe, 2pn) 75Kr reaction at beam energies of 177 and 190 MeV. In the reaction study at 177 MeV, the γ-rays were detected in coincidence with neutrons and mass-75 nuclei and in the reaction at 190 MeV only γγ-coincidence data were collected. Using the γγ-neutron gated γγ- and Recoil-γγ-coincidence techniques, we were able to develop the level scheme up to spins ( {37+}/{2}) and ( {31-}/{2}) in the positive- and negative-parity bands, respectively. These spins are high enough to allow us to study alignment effects in this mass region. The signature splitting at low spin can be reproduced in a cranked shell model calculation assuming a quadrupole deformation β2 = 0.37 and a slightly triaxial ( γ≈ -10°) shape for positive-parity states but an axial shape for the negative-parity sequence. The spin alignment as a function of rotational frequency has been studied; in the positive-parity band alignment is observed at a rotational frequency of h̵ω ≈ 0.63 MeV and in the negative-parity band the alignment occurs at h̵ω ≈ 0.57 MeV. The observed alignment in both bands is associated with a pair of g{9}/{2} protons, and the difference in the alignment frequencies is thought to be due to differing intrinsic shapes.

  2. Longitudinal spin relaxation of donor-bound electrons in direct band-gap semiconductors

    Science.gov (United States)

    Linpeng, Xiayu; Karin, Todd; Durnev, M. V.; Barbour, Russell; Glazov, M. M.; Sherman, E. Ya.; Watkins, S. P.; Seto, Satoru; Fu, Kai-Mei C.

    2016-09-01

    We measure the donor-bound electron longitudinal spin-relaxation time (T1) as a function of magnetic field (B ) in three high-purity direct band-gap semiconductors: GaAs, InP, and CdTe, observing a maximum T1 of 1.4, 0.4, and 1.2 ms, respectively. In GaAs and InP at low magnetic field, up to ˜2 T, the spin-relaxation mechanism is strongly density and temperature dependent and is attributed to the random precession of the electron spin in hyperfine fields caused by the lattice nuclear spins. In all three semiconductors at high magnetic field, we observe a power-law dependence T1∝B-ν with 3 ≲ν ≲4 . Our theory predicts that the direct spin-phonon interaction is important in all three materials in this regime in contrast to quantum dot structures. In addition, the "admixture" mechanism caused by Dresselhaus spin-orbit coupling combined with single-phonon processes has a comparable contribution in GaAs. We find excellent agreement between high-field theory and experiment for GaAs and CdTe with no free parameters, however a significant discrepancy exists for InP.

  3. Structure of 72,74Se at high spin

    Indian Academy of Sciences (India)

    R Palit; H C Jain; P K Joshi; J A Sheikh

    2001-07-01

    Lifetimes of high spin states up to =22+ in the yrast positive parity bands have been measured to investigate the shape evolution with increasing spin in 72,74Se. The t values derived from these measurements indicate that prolate shape stabilizes for 72Se, while a triaxial shape develops for 74Se at higher spins. Comparison of the observed trend in t with spin for 72,74Se with that of the corresponding kryptones isotones emphasizes the stability provided by = 38 prolate shell gap even at high rotational frequency.

  4. A strategy to create spin-split metallic bands on silicon using a dense alloy layer.

    Science.gov (United States)

    Gruznev, Dimitry V; Bondarenko, Leonid V; Matetskiy, Andrey V; Yakovlev, Alexey A; Tupchaya, Alexandra Y; Eremeev, Sergey V; Chulkov, Evgeniy V; Chou, Jyh-Pin; Wei, Ching-Ming; Lai, Ming-Yu; Wang, Yuh-Lin; Zotov, Andrey V; Saranin, Alexander A

    2014-04-22

    To exploit Rashba effect in a 2D electron gas on silicon surface for spin transport, it is necessary to have surface reconstruction with spin-split metallic surface-state bands. However, metals with strong spin-orbit coupling (e.g., Bi, Tl, Sb, Pt) induce reconstructions on silicon with almost exclusively spin-split insulating bands. We propose a strategy to create spin-split metallic bands using a dense 2D alloy layer containing a metal with strong spin-orbit coupling and another metal to modify the surface reconstruction. Here we report two examples, i.e., alloying reconstruction with Na and Tl/Si(111)1 × 1 reconstruction with Pb. The strategy provides a new paradigm for creating metallic surface state bands with various spin textures on silicon and therefore enhances the possibility to integrate fascinating and promising capabilities of spintronics with current semiconductor technology.

  5. Probing the Spin-Polarized Electronic Band Structure in Monolayer Transition Metal Dichalcogenides by Optical Spectroscopy

    Science.gov (United States)

    Wang, Zefang; Zhao, Liang; Mak, Kin Fai; Shan, Jie

    2017-02-01

    We study the electronic band structure in the K/K' valleys of the Brillouin zone of monolayer WSe2 and MoSe2 by optical reflection and photoluminescence spectroscopy on dual-gated field-effect devices. Our experiment reveals the distinct spin polarization in the conduction bands of these compounds by a systematic study of the doping dependence of the A and B excitonic resonances. Electrons in the highest-energy valence band and the lowest-energy conduction band have antiparallel spins in monolayer WSe2, and parallel spins in monolayer MoSe2. The spin splitting is determined to be hundreds of meV for the valence bands and tens of meV for the conduction bands, which are in good agreement with first principles calculations. These values also suggest that both n- and p-type WSe2 and MoSe2 can be relevant for spin- and valley-based applications

  6. High-spin nuclear spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Diamond, R.M.

    1986-07-01

    High-spin spectroscopy is the study of the changes in nuclear structure, properties, and behavior with increasing angular momentum. It involves the complex interplay between collective and single-particle motion, between shape and deformation changes, particle alignments, and changes in the pairing correlations. A review of progress in theory, experimentation, and instrumentation in this field is given. (DWL)

  7. The spin polarized band structure of strained thin films of gadolinium

    Energy Technology Data Exchange (ETDEWEB)

    Waldfried, C.; Dowben, P.A. [Univ. of Nebraska, Lincoln, NE (United States); Vescovo, E. [Brookhaven National Lab., Upton, NY (United States). National Synchrotron Light Source

    1998-12-31

    The magnetic properties of strained thin films of gadolinium are characterized by a wave vector and thickness dependence of the exchange splitting. The spin-resolved band structure has been mapped by spin polarized photoemission, and provides considerable insight into the relationship between magnetism of local moment systems, and band structure.

  8. Spin-flip scattering and band structure mismatch effect on transport of pure spin across ferromagnetic semimetal/metal material interfaces

    Science.gov (United States)

    Pasanai, K.

    2016-03-01

    The tunneling conductance spectra of a ferromagnetic semimetal/metal junction, where there were electrons and holes with the same spin directions as the essential conducting particle, was theoretically studied based on a scattering approach in a ballistic regime. The main area of interest was to perform a high spin polarization by considering the effect of the interfacial scattering at the interface that was composed of normal and spin-flip scattering, the particle effective mass mismatch on the reflection and transmission probabilities, and spin polarization of conductance. It was found that the spin polarization of conductance decreased with increasing spin-flip scattering. Interestingly, the normal scattering can cause the spin polarization of the conductance to reach a maximum value in the presence of both kinds of scattering. When the particle effective mass mismatch was considered, the spin polarization of conductance was large when the electron effective mass in the valence band was smaller than that in the conduction band. However, in this calculation, the results of a ferromagnetic semimetal/metal junction behaved similarly to those of a ferromagnetic metal/metal junction.

  9. Spin assignment of the first discovered superdeformed band 152Dy(1)

    Institute of Scientific and Technical Information of China (English)

    雷奕安; 曾谨言

    1996-01-01

    Using the several criteria for the spin assignment of a rotational band based on very general argument,the spin of the lowest level observed in the yrast SD band 152Dy(1) is assigned to be I0=26(Eγ(I0+2→I0)=602.4keV),and it is demonstrated that spin assignments of I0≤25 as well as I-≥27 are in contradiction with these criteria.

  10. High-field spin dynamics of antiferromagnetic quantum spin chains

    DEFF Research Database (Denmark)

    Enderle, M.; Regnault, L.P.; Broholm, C.;

    2000-01-01

    The characteristic internal order of macroscopic quantum ground states in one-dimensional spin systems is usually not directly accessible, but reflected in the spin dynamics and the field dependence of the magnetic excitations. In high magnetic fields quantum phase transitions are expected. We...... present recent work on the high-field spin dynamics of the S = I antiferromagnetic Heisenberg chains NENP (Haldane ground state) and CsNiCl3 (quasi-1D HAF close to the quantum critical point), the uniform S = 1/2 chain CTS, and the spin-Peierls system CuGeO3. (C) 2000 Elsevier Science B,V. All rights...

  11. Spin-Polarized Electron Emission from Superlattices with Zero Conduction Band Offset

    Energy Technology Data Exchange (ETDEWEB)

    Clendenin, James E

    1998-11-09

    Electron spin polarization as high as 86% has been reproducibly obtained from strained Al{sub x}In{sub y}Ga{sub 1-x-y}As/GaAs superlattice with minimal conduction band offset at the heterointerfaces. The modulation doping of the SL provides high polarization and high quantum yield at the polarization maximum. The position of the maximum can be easily tuned to an excitation wavelength by choice of the SL composition. Further improvement of the emitter parameters can be expected with additional optimization of the SL structure parameters.

  12. High spin isomer beam line at RIKEN

    Energy Technology Data Exchange (ETDEWEB)

    Kishida, T.; Ideguchi, E.; Wu, H.Y. [Institute of Physical and Chemical Research, Saitama (Japan)] [and others

    1996-12-31

    Nuclear high spin states have been the subject of extensive experimental and theoretical studies. For the production of high spin states, fusion reactions are usually used. The orbital angular momentum brought in the reaction is changed into the nuclear spin of the compound nucleus. However, the maximum induced angular momentum is limited in this mechanism by the maximum impact parameter of the fusion reaction and by the competition with fission reactions. It is, therefore, difficult to populate very high spin states, and as a result, large {gamma}-detector arrays have been developed in order to detect subtle signals from such very high spin states. The use of high spin isomers in the fusion reactions can break this limitation because the high spin isomers have their intrinsic angular momentum, which can bring the additional angular momentum without increasing the excitation energy. There are two methods to use the high spin isomers for secondary reactions: the use of the high spin isomers as a target and that as a beam. A high spin isomer target has already been developed and used for several experiments. But this method has an inevitable shortcoming that only {open_quotes}long-lived{close_quotes} isomers can be used for a target: {sup 178}Hf{sup m2} (16{sup +}) with a half-life of 31 years in the present case. By developing a high spin isomer beam, the authors can utilize various short-lived isomers with a short half-life around 1 {mu}s. The high spin isomer beam line of RIKEN Accelerator Facility is a unique apparatus in the world which provides a high spin isomer as a secondary beam. The combination of fusion-evaporation reaction and inverse kinematics are used to produce high spin isomer beams; in particular, the adoption of `inverse kinematics` is essential to use short-lived isomers as a beam.

  13. Motion Analysis of Fiber Band in Compact Field of Compact Spinning

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The technological process of compact spinning and the compact procedure of fiber band in compact field are briefly illustrated. The motions of fiber band in compact field are discussed theoretically from which tilting angle of suction slot in profile tube, additional twists created by fiber band's rotating around its own axis and ultimate twists in compact yarn are deduced accordingly. The existence of additional twists is also verified through experiments.

  14. A high-spin organic diradical as a spin filter.

    Science.gov (United States)

    Shil, Suranjan; Bhattacharya, Debojit; Misra, Anirban; Klein, Douglas J

    2015-09-28

    Here, in this work we have designed a molecular bridge structure which can be used as a spin filter where the prototypical highly ferromagnetic m-phenylene connected bis(aminoxyl) diradical is used as a bridging fragment between two semi-infinitely widened gold (Au) electrodes along the [100] direction. A state-of-the-art non-equilibrium Green function's (NEGF) method coupled with the density functional theory (DFT) was carried out on this two-probe molecular bridge system to understand its electrical spin transport characteristics. The spin current at various bias voltages from 0.00 V to 4.00 V at intervals of 0.20 V for this Au-diradical-Au molecular junction is evaluated. We also quantify the bias-dependent spin injection coefficients (BDSIC) at different bias voltages and also the spin-filter efficiency at equilibrium, i.e., at zero bias voltage. Also plots of BDSIC vs. voltage, the up- and down-spin current vs. voltage (I-V) curves, and density of states (DOS) at zero bias voltage are evaluated.

  15. High-Spin States in ~(86)Sr

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    The previous works for high spins states of 86Sr were very scarce. In the past, the spin of highest level of 86Sr was 13 found by the reaction 84Kr(α, 2nγ)86Sr in 28 MeV. The current work updates the level scheme of 86Sr to get more information about high spin states in 86Sr.

  16. Predicting superdeformed rotational band-head spin in A ∼ 190 mass region using variable moment of inertia model

    Indian Academy of Sciences (India)

    V S Uma; Alpana Goel; Archana Yadav; A K Jain

    2016-01-01

    The band-head spin (0) of superdeformed (SD) rotational bands in ∼ 190 mass region is predicted using the variable moment of inertia (VMI) model for 66 SD rotational bands. The superdeformed rotational bands exhibited considerably good rotational property and rigid behaviour. The transition energies were dependent on the prescribed band-head spins. The ratio of transition energies over spin /2 (RTEOS) vs. angular momentum ( ) have confirmed the rigid behaviour, provided the band-head spin value is assigned correctly. There is a good agreement between the calculated and the observed transition energies. This method gives a very comprehensive interpretation for spin assignment of SD rotational bands which could help in designing future experiments for SD bands.

  17. Full-zone analysis of relativistic spin splitting at band anticrossings: The case of zinc-blende semiconductors

    DEFF Research Database (Denmark)

    Chantis, Athanasios N.; Christensen, Niels Egede; Svane, Axel

    2010-01-01

    We show that the band spin splitting caused by spin-orbit interaction in crystal structures with no inversion symmetry is strongly influenced by band anticrossing. The splitting is always enhanced for one of the anticrossing bands and suppressed for the other. There are two limiting cases. In the...

  18. Saturation recovery EPR and ELDOR at W-band for spin labels

    Science.gov (United States)

    Froncisz, Wojciech; Camenisch, Theodore G.; Ratke, Joseph J.; Anderson, James R.; Subczynski, Witold K.; Strangeway, Robert A.; Sidabras, Jason W.; Hyde, James S.

    2008-08-01

    A reference arm W-band (94 GHz) microwave bridge with two sample-irradiation arms for saturation recovery (SR) EPR and ELDOR experiments is described. Frequencies in each arm are derived from 2 GHz synthesizers that have a common time-base and are translated to 94 GHz in steps of 33 and 59 GHz. Intended applications are to nitroxide radical spin labels and spin probes in the liquid phase. An enabling technology is the use of a W-band loop-gap resonator (LGR) [J.W. Sidabras, R.R. Mett, W. Froncisz, T.G. Camenisch, J.R. Anderson, J.S. Hyde, Multipurpose EPR loop-gap resonator and cylindrical TE 011 cavity for aqueous samples at 94 GHz, Rev. Sci. Instrum. 78 (2007) 034701]. The high efficiency parameter (8.2 GW -1/2 with sample) permits the saturating pump pulse level to be just 5 mW or less. Applications of SR EPR and ELDOR to the hydrophilic spin labels 3-carbamoyl-2,2,5,5-tetra-methyl-3-pyrroline-1-yloxyl (CTPO) and 2,2,6,6,-tetramethyl-4-piperidone-1-oxyl (TEMPONE) are described in detail. In the SR ELDOR experiment, nitrogen nuclear relaxation as well as Heisenberg exchange transfer saturation from pumped to observed hyperfine transitions. SR ELDOR was found to be an essential method for measurements of saturation transfer rates for small molecules such as TEMPONE. Free induction decay (FID) signals for small nitroxides at W-band are also reported. Results are compared with multifrequency measurements of T1e previously reported for these molecules in the range of 2-35 GHz [J.S. Hyde, J.-J. Yin, W.K. Subczynski, T.G. Camenisch, J.J. Ratke, W. Froncisz, Spin label EPR T 1 values using saturation recovery from 2 to 35 GHz. J. Phys. Chem. B 108 (2004) 9524-9529]. The values of T1e decrease at 94 GHz relative to values at 35 GHz.

  19. Orientation selective DEER measurements on vinculin tail at X-band frequencies reveal spin label orientations

    Science.gov (United States)

    Abé, Christoph; Klose, Daniel; Dietrich, Franziska; Ziegler, Wolfgang H.; Polyhach, Yevhen; Jeschke, Gunnar; Steinhoff, Heinz-Jürgen

    2012-03-01

    Double electron electron resonance (DEER) spectroscopy has been established as a valuable method to determine distances between spin labels bound to protein molecules. Caused by selective excitation of molecular orientations DEER primary data also depend on the mutual orientation of the spin labels. For a doubly spin labeled variant of the cytoskeletal protein vinculin tail strong orientation selection can be observed already at X-band frequencies, which allows us to reduce the problem to the relative orientation of two molecular axes and the spin-spin axis parameterized by three angles. A full grid search of parameter space reveals that the DEER experiment introduces parameter-space symmetry higher than the symmetry of the spin Hamiltonian. Thus, the number of equivalent parameter sets is twice as large as expected and the relative orientation of the two spin labels is ambiguous. Except for this inherent ambiguity the most probable relative orientation of the two spin labels can be determined with good confidence and moderate uncertainty by global fitting of a set of five DEER experiments at different offsets between pump and observer frequency. The experiment provides restraints on the angles between the z axis of the nitroxide molecular frame and the spin-spin vector and on the dihedral between the two z axes. When using the same type of label at both sites, assignment of the angle restraints is ambiguous and the sign of the dihedral restraint is also ambiguous.

  20. Spin polarized surface resonance bands in single layer Bi on Ge(1 1 1)

    Science.gov (United States)

    Bottegoni, F.; Calloni, A.; Bussetti, G.; Camera, A.; Zucchetti, C.; Finazzi, M.; Duò, L.; Ciccacci, F.

    2016-05-01

    The spin features of surface resonance bands in single layer Bi on Ge(1 1 1) are studied by means of spin- and angle-resolved photoemission spectroscopy and inverse photoemission spectroscopy. We characterize the occupied and empty surface states of Ge(1 1 1) and show that the deposition of one monolayer of Bi on Ge(1 1 1) leads to the appearance of spin-polarized surface resonance bands. In particular, the C 3v symmetry, which Bi adatoms adopt on Ge(1 1 1), allows for the presence of Rashba-like occupied and unoccupied electronic states around the \\overline{\\text{M}} point of the Bi surface Brillouin zone with a giant spin-orbit constant |{α\\text{R}}| =≤ft(1.4+/- 0.1\\right) eV · Å.

  1. Spin-parity assignments and extension of the 02+ band in 158Er

    Directory of Open Access Journals (Sweden)

    Dinoko T S

    2013-12-01

    Full Text Available Low and medium spin collective structures in 158Er have been studied using the 150Sm(12C,4nγγ fusion-evaporation reaction at a beam energy of Elab = 65 MeV. A band built on the 02+ excitation has been established and extended to Jπ = 18+ from the analysis of γ-γ coincidence relationships, intensity arguments and DCO ratios. The 02+ band in 158Er presents a similar trend to the 02+ bands in the lighter N = 90 isotones but lies about 125 keV higher. This systematic trend supports a similar configuration for the 02+ bands in the N = 90 isotones.

  2. Ground Band and Excited Band of Spin-1 BEC in Cigar Shaped Laser Trap

    Institute of Scientific and Technical Information of China (English)

    PANG Wei; LI Zhi-Bing; BAO Cheng-Guang

    2007-01-01

    The wavefunctions that conserve the total spin are constructed for the fully condensed states and the states with one particle excited. A set of equations are deduced for the spatial longitudinal wavefunctions and the chemical potentials. These equations are solved numerically for 23Na and 87Rb condensates. The deformed trap shows significant effects on the spectrum. This implies that the spin effect of the spinor BEC are more easily detected in an optical trap of larger aspect ratio.

  3. Band structure and spin texture of Bi2Se3 3 d ferromagnetic metal interface

    Science.gov (United States)

    Zhang, Jia; Velev, Julian P.; Dang, Xiaoqian; Tsymbal, Evgeny Y.

    2016-07-01

    The spin-helical surface states in a three-dimensional topological insulator (TI), such as Bi2Se3 , are predicted to have superior efficiency in converting charge current into spin polarization. This property is said to be responsible for the giant spin-orbit torques observed in ferromagnetic metal/TI structures. In this work, using first-principles and model tight-binding calculations, we investigate the interface between the topological insulator Bi2Se3 and 3 d -transition ferromagnetic metals Ni and Co. We find that the difference in the work functions of the topological insulator and the ferromagnetic metals shift the topological surface states down about 0.5 eV below the Fermi energy where the hybridization of these surface states with the metal bands destroys their helical spin structure. The band alignment of Bi2Se3 and Ni (Co) places the Fermi energy far in the conduction band of bulk Bi2Se3 , where the spin of the carriers is aligned with the magnetization in the metal. Our results indicate that the topological surface states are unlikely to be responsible for the huge spin-orbit torque effect observed experimentally in these systems.

  4. Sub-picosecond time resolved infrared spectroscopy of high-spin state formation in Fe(II) spin crossover complexes

    DEFF Research Database (Denmark)

    Døssing, Anders Rørbæk; Wolf, Matthias M. N.; Gross, Ruth

    2008-01-01

      The photoinduced low-spin (S = 0) to high-spin (S = 2) transition of the iron(II) spin-crossover systems [Fe(btpa)](PF6)2 and [Fe(b(bdpa))](PF6)2 in solution have been studied for the first time by means of ultrafast transient infrared spectroscopy at room temperature. Negative and positive...... absorption cross sections. The simulated infrared difference spectra are dominated by an increase of the absorption cross section upon high-spin state formation in accordance with the experimental infrared spectra....... infrared difference bands between 1000 and 1065 cm-1 that appear within the instrumental system response time of 350 fs after excitation at 387 nm display the formation of the vibrationally unrelaxed and hot high-spin 5T2 state. Vibrational relaxation is observed and characterized by the time constants 9...

  5. Spin-orbital exchange of strongly interacting fermions in the p band of a two-dimensional optical lattice.

    Science.gov (United States)

    Zhou, Zhenyu; Zhao, Erhai; Liu, W Vincent

    2015-03-13

    Mott insulators with both spin and orbital degeneracy are pertinent to a large number of transition metal oxides. The intertwined spin and orbital fluctuations can lead to rather exotic phases such as quantum spin-orbital liquids. Here, we consider two-component (spin 1/2) fermionic atoms with strong repulsive interactions on the p band of the optical square lattice. We derive the spin-orbital exchange for quarter filling of the p band when the density fluctuations are suppressed, and show that it frustrates the development of long-range spin order. Exact diagonalization indicates a spin-disordered ground state with ferro-orbital order. The system dynamically decouples into individual Heisenberg spin chains, each realizing a Luttinger liquid accessible at higher temperatures compared to atoms confined to the s band.

  6. Lifetime measurement of high spin states in {sup 75}Kr

    Energy Technology Data Exchange (ETDEWEB)

    Trivedi, T. [Department of Physics, University of Allahabad, Allahabad-211001 (India); Palit, R. [Tata Institute of Fundamental Research, Mumbai-400005 (India); Negi, D. [Inter University Accelerator Centre, New Delhi-110067 (India); Naik, Z. [Tata Institute of Fundamental Research, Mumbai-400005 (India); Yang, Y.-C. [Department of Physics, Shanghai Jiao Tong University, Shanghai 200240 (China); Sun, Y. [Department of Physics, Shanghai Jiao Tong University, Shanghai 200240 (China); Department of Physics and Astronomy, University of Tennessee, Knoxville, TN 37996 (United States); Sheikh, J.A. [Department of Physics and Astronomy, University of Tennessee, Knoxville, TN 37996 (United States); Physics Division, Oak Ridge National Laboratory, PO Box 2008, Oak Ridge, TN 37831 (United States); Department of Physics, University of Kashmir, Srinagar 190 006 (India); Dhal, A. [Department of Physics, Banaras Hindu University, Varanasi 221005 (India); Raju, M.K. [Department of Nuclear Physics, Andhra University, Visakhapatnam-530003 (India); Appannababu, S. [Department of Physics, MS University of Baroda, Vadodara-390002 (India); Kumar, S. [Department of Physics and Astrophysics, University of Delhi, Delhi-110007 (India); Choudhury, D. [Department of Physics, IIT Roorkee, Roorkee-247667 (India); Maurya, K. [Department of Physics, University of Allahabad, Allahabad-211001 (India); Mahanto, G.; Kumar, R.; Singh, R.P.; Muralithar, S. [Inter University Accelerator Centre, New Delhi-110067 (India); Jain, A.K. [Department of Physics, IIT Roorkee, Roorkee-247667 (India); Jain, H.C. [Tata Institute of Fundamental Research, Mumbai-400005 (India); Pancholi, S.C. [Inter University Accelerator Centre, New Delhi-110067 (India)

    2010-03-01

    The lifetimes of high spin states of {sup 75}Kr have been determined via {sup 50}Cr ({sup 28}Si, 2pn) {sup 75}Kr reaction in positive parity band using the Doppler-shift attenuation method. The transition quadrupole moments Q{sub t} deduced from lifetime measurements have been compared with {sup 75}Br. Experimental results obtained from lifetime measurement are interpreted in the framework of projected shell model.

  7. Multi Band Gap High Efficiency Converter (RAINBOW)

    Science.gov (United States)

    Bekey, I.; Lewis, C.; Phillips, W.; Shields, V.; Stella, P.

    1997-01-01

    The RAINBOW multi band gap system represents a unique combination of solar cells, concentrators and beam splitters. RAINBOW is a flexible system which can readily expand as new high efficiency components are developed.

  8. In-beam spectroscopy of medium- and high-spin states in $^{133}$Ce

    CERN Document Server

    Ayangeakaa, A D; Petrache, C M; Guo, S; Zhao, P W; Matta, J T; Nayak, B K; Patel, D; Janssens, R V F; Carpenter, M P; Chiara, C J; Kondev, F G; Lauritsen, T; Seweryniak, D; Zhu, S; Ghugre, S S; Palit, R

    2016-01-01

    Medium and high-spin states in $^{133}$Ce were investigated using the $^{116}$Cd($^{22}$Ne, $5n$) reaction and the Gammasphere array. The level scheme was extended up to an excitation energy of $\\sim22.8$ MeV and spin 93/2 . Eleven bands of quadrupole transitions and two new dipole bands are identified. The connections to low-lying states of the previously known, high-spin triaxial bands were firmly established, thus fixing the excitation energy and, in many cases, the spin parity of the levels. Based on comparisons with cranked Nilsson-Strutinsky calculations and tilted axis cranking covariant density functional theory, it is shown that all observed bands are characterized by pronounced triaxiality. Competing multiquasiparticle configurations are found to contribute to a rich variety of collective phenomena in this nucleus.

  9. HIGH-SPIN OCTUPOLE CORRELATIONS IN THE N=86, ND-146 AND SM-148 NUCLEI

    NARCIS (Netherlands)

    LIEDER, RM; BACELAR, JC; SINGH, PP; ALBER, D; BALABANSKI, D; GAST, W; GRAWE, H; HEBBINGHAUS, G; JONGMAN, [No Value; MOREK, T; NOORMAN, RF; RZACAURBAN, T; SCHNARE, H; THOMS, M; ZELL, O; NAZAREWICZ, W

    1991-01-01

    High-spin states in Nd-146 and Sm-148 have been populated using the C-13 + Xe-136 and Ne-22 + Te-130 compound nucleus reactions. Alternating parity bands built on the ground state are observed to spin I = (19) and I = (27) in Nd-146 and Sm-148 respectively. Analysis of the data done in terms of the

  10. Angle-resolved spin wave band diagrams of square antidot lattices studied by Brillouin light scattering

    Energy Technology Data Exchange (ETDEWEB)

    Gubbiotti, G.; Tacchi, S. [Istituto Officina dei Materiali del Consiglio Nazionale delle Ricerche (IOM-CNR), Sede di Perugia, c/o Dipartimento di Fisica e Geologia, Via A. Pascoli, I-06123 Perugia (Italy); Montoncello, F.; Giovannini, L. [Dipartimento di Fisica e Scienze della Terra, Università di Ferrara, Via G. Saragat 1, I-44122 Ferrara (Italy); Madami, M.; Carlotti, G. [Dipartimento di Fisica e Geologia, Università di Perugia, Via A. Pascoli, I-06123 Perugia (Italy); Ding, J.; Adeyeye, A. O. [Information Storage Materials Laboratory, Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117576 (Singapore)

    2015-06-29

    The Brillouin light scattering technique has been exploited to study the angle-resolved spin wave band diagrams of squared Permalloy antidot lattice. Frequency dispersion of spin waves has been measured for a set of fixed wave vector magnitudes, while varying the wave vector in-plane orientation with respect to the applied magnetic field. The magnonic band gap between the two most dispersive modes exhibits a minimum value at an angular position, which exclusively depends on the product between the selected wave vector magnitude and the lattice constant of the array. The experimental data are in very good agreement with predictions obtained by dynamical matrix method calculations. The presented results are relevant for magnonic devices where the antidot lattice, acting as a diffraction grating, is exploited to achieve multidirectional spin wave emission.

  11. Electronic band structure of Cu(2)O by spin density functional theory.

    Science.gov (United States)

    French, M; Schwartz, R; Stolz, H; Redmer, R

    2009-01-07

    The band structure of Cu(2)O is calculated using density functional theory in the generalized gradient approximation. By taking spin-orbit coupling into account the split between the Γ(7)(+) and the Γ(8)(+) valence band states is obtained as 128 meV. The highest valence band shows a noticeable nonparabolicity close to the Γ point. This is important for the quantitative description of excitons in this material, which is considered to be the best candidate for the confirmation that Bose-Einstein condensation also occurs in excitonic systems.

  12. Spin-split bands of metallic hydrogenated ZnO ( 10 1 ¯ 0 surface: First-principles study

    Directory of Open Access Journals (Sweden)

    Moh. Adhib Ulil Absor

    2016-02-01

    Full Text Available For spintronics applications, generation of significant spin transport is required, which is achieved by applying a semiconductor surface exhibiting metallic spin-split surface-state bands. We show that metallic spin-split surface-state bands are achieved on hydrogenated ZnO ( 10 1 ¯ 0 surface by using first-principles density-functional theory calculations. We find that these metallic surface-state bands with dominant Zn-s and p orbitals exhibit Rashba spin splitting with a strong anisotropic character. This finding makes spintronics devices using oxide electronics surface materials possible.

  13. Collectivity of high spin states in {sup 84}Zr

    Energy Technology Data Exchange (ETDEWEB)

    Lister, C.J.; Blumenthal, D.; Crowell, B. [and others

    1995-08-01

    {sup 84}Zr is one of the most extensively studied of the A {approximately} 80 rotors, both from theoretical and experimental approaches. It was predicted to be a good candidate to support superdeformation, and to show interesting spectroscopic properties including saturation of its shell-model space at lower spin. We performed an experiment using Gammasphere in its early implementation phase. The reaction of {sup 29}Si on {sup 58}Ni was used to strongly populate {sup 84}Zr at high spin. Thin and thick targets were used to allow the extraction of transitional matrix elements at very high spin, and to allow a sensitive search for superdeformed states. Data analysis is in progress. The large data set allowed us to extend the previously known bands considerably. Candidates for a staggered M1-band, found previously {sup 86}Zr, were located. To date, no evidence for superdeformed bands was found. Analysis was slowed by the relocation of all the participants in this experiment, but we hope to complete the lifetime analysis this year. This analysis has become especially topical, due to reported measurements of superdeformation in this region.

  14. g-factor Measurement of High Spin States in 83Y by TMF-IMPAD

    Science.gov (United States)

    Daqing, Yuan; Yongnan, Zheng; Dongmei, Zhou; Yi, Zuo; Enpeng, Du; Xiao, Duan; Chaohui, Wang; Qi, Luo; xiaoguang, Wu; Guangsheng, Li; Shuxian, Wen; Lihua, Zhu; Guoji, Xu; Zaochun, Gao; Yongshou, Chen; Shengyun, Zhu

    2006-11-01

    The g-factors of high spin states of the positive parity yrast rotational band up to spin I=41/2+ in 83Y have been measured by a transient-magnetic-field ion implantation perturbed angular distribution method. A positive peak structure of g-factor vs spin has been observed, which provides an experimental evidence for the g9/2 proton alignment followed by the g9/2 neutron alignment.

  15. High-Spin Cobalt Hydrides for Catalysis

    Energy Technology Data Exchange (ETDEWEB)

    Holland, Patrick L. [Univ. of Rochester, NY (United States)

    2013-08-29

    Organometallic chemists have traditionally used catalysts with strong-field ligands that give low-spin complexes. However, complexes with a weak ligand field have weaker bonds and lower barriers to geometric changes, suggesting that they may lead to more rapid catalytic reactions. Developing our understanding of high-spin complexes requires the use of a broader range of spectroscopic techniques, but has the promise of changing the mechanism and/or selectivity of known catalytic reactions. These changes may enable the more efficient utilization of chemical resources. A special advantage of cobalt and iron catalysts is that the metals are more abundant and cheaper than those currently used for major industrial processes that convert unsaturated organic molecules and biofeedstocks into useful chemicals. This project specifically evaluated the potential of high-spin cobalt complexes for small-molecule reactions for bond rearrangement and cleavage reactions relevant to hydrocarbon transformations. We have learned that many of these reactions proceed through crossing to different spin states: for example, high-spin complexes can flip one electron spin to access a lower-energy reaction pathway for beta-hydride elimination. This reaction enables new, selective olefin isomerization catalysis. The high-spin cobalt complexes also cleave the C-O bond of CO2 and the C-F bonds of fluoroarenes. In each case, the detailed mechanism of the reaction has been determined. Importantly, we have discovered that the cobalt catalysts described here give distinctive selectivities that are better than known catalysts. These selectivities come from a synergy between supporting ligand design and electronic control of the spin-state crossing in the reactions.

  16. Quantum distance and the Euler number index of the Bloch band in a one-dimensional spin model.

    Science.gov (United States)

    Ma, Yu-Quan

    2014-10-01

    We study the Riemannian metric and the Euler characteristic number of the Bloch band in a one-dimensional spin model with multisite spins exchange interactions. The Euler number of the Bloch band originates from the Gauss-Bonnet theorem on the topological characterization of the closed Bloch states manifold in the first Brillouin zone. We study this approach analytically in a transverse field XY spin chain with three-site spin coupled interactions. We define a class of cyclic quantum distance on the Bloch band and on the ground state, respectively, as a local characterization for quantum phase transitions. Specifically, we give a general formula for the Euler number by means of the Berry curvature in the case of two-band models, which reveals its essential relation to the first Chern number of the band insulators. Finally, we show that the ferromagnetic-paramagnetic phase transition in zero temperature can be distinguished by the Euler number of the Bloch band.

  17. Strongly correlated flat-band systems: The route from Heisenberg spins to Hubbard electrons

    Science.gov (United States)

    Derzhko, Oleg; Richter, Johannes; Maksymenko, Mykola

    2015-05-01

    On a large class of lattices (such as the sawtooth chain, the kagome and the pyrochlore lattices), the quantum Heisenberg and the repulsive Hubbard models may host a completely dispersionless (flat) energy band in the single-particle spectrum. The flat-band states can be viewed as completely localized within a finite volume (trap) of the lattice and allow for construction of many-particle states, roughly speaking, by occupying the traps with particles. If the flat-band happens to be the lowest-energy one, the manifold of such many-body states will often determine the ground-state and low-temperature physics of the models at hand even in the presence of strong interactions. The localized nature of these many-body states makes possible the mapping of this subset of eigenstates onto a corresponding classical hard-core system. As a result, the ground-state and low-temperature properties of the strongly correlated flat-band systems can be analyzed in detail using concepts and tools of classical statistical mechanics (e.g., classical lattice-gas approach or percolation approach), in contrast to more challenging quantum many-body techniques usually necessary to examine strongly correlated quantum systems. In this review, we recapitulate the basic features of the flat-band spin systems and briefly summarize earlier studies in the field. The main emphasis is made on recent developments which include results for both spin and electron flat-band models. In particular, for flat-band spin systems, we highlight field-driven phase transitions for frustrated quantum Heisenberg antiferromagnets at low temperatures, chiral flat-band states, as well as the effect of a slight dispersion of a previously strictly flat-band due to nonideal lattice geometry. For electronic systems, we discuss the universal low-temperature behavior of several flat-band Hubbard models, the emergence of ground-state ferromagnetism in the square-lattice Tasaki-Hubbard model and the related Pauli

  18. Determination of the 14N quadrupole coupling constant of nitroxide spin probes by W-band ELDOR-detected NMR

    Science.gov (United States)

    Florent, Marc; Kaminker, Ilia; Nagarajan, Vijayasarathi; Goldfarb, Daniella

    2011-06-01

    Nitroxide spin probe electron paramagnetic resonance (EPR) has proven to be a very successful method to probe local polarity and solvent hydrogen bonding properties at the molecular level. The g xx and the 14N hyperfine A zz principal values are the EPR parameters of the nitroxide spin probe that are sensitive to these properties and are therefore monitored experimentally. Recently, the 14N quadrupole interaction of nitroxides has been shown to be also highly sensitive to polarity and H-bonding (A. Savitsky et al., J. Phys. Chem. B 112 (2008) 9079). High-field electron spin echo envelope modulation (ESEEM) was used successfully to determine the P xx and P yy principal components of the 14N quadrupole tensor. The P zz value was calculated from the traceless character of the quadrupole tensor. We introduce here high-field (W-band, 95 GHz, 3.5 T) electron-electron double resonance (ELDOR)-detected NMR as a method to obtain the 14N P zz value directly, together with A zz. This is complemented by W-band hyperfine sublevel correlation (HYSCORE) measurements carried out along the g xx direction to determine the principal P xx and P yy components. Through measurements of TEMPOL dissolved in solvents of different polarities, we show that A zz increases, while | P zz| decreases with polarity, as predicted by Savitsky et al.

  19. Spin-orbit mechanism of predissociation in the Wulf band of ozone

    Science.gov (United States)

    Grebenshchikov, S. Yu.; Qu, Z.-W.; Zhu, H.; Schinke, R.

    2006-07-01

    Previously calculated resonance widths of the ground vibrational levels in the electronic states 1A″3 (A23) and 1A'3 (B23), which belong to the Wulf band system of ozone, are significantly smaller than observed experimentally. We demonstrate that predissociation is drastically enhanced by spin-orbit coupling between 1A″3/XA'1 and 1A'3/1A″3. Multistate quantum mechanical calculations using ab initio spin-orbit coupling matrix elements give linewidths of optically bright components of the right order of magnitude.

  20. Lifetimes of high-spin states in {sup 162}Yb

    Energy Technology Data Exchange (ETDEWEB)

    Carpenter, M.P.; Janssens, R.V.F.; Henry, R.G. [and others

    1995-08-01

    A measurement on lifetimes of high-spin states in the yrast and near-yrast rotational bands in {sup 162}Yb was carried out at ATLAS in order to determine the evolution of collectivity as a function of angular momentum using the {sup 126}Te({sup 40}Ar,4n){sup 162}Yb reaction at 170 MeV. Previous lifetime measurements in the {sup 164,166,168}Yb isotopes showed a dramatic decrease in the transition quadrupole moment Q{sub t} with increasing spin. It was suggested that this decrease in Q{sub t} is brought about by the rotationally-induced deoccupation of high-j configurations, mainly i{sub 13/2} neutrons. If this interpretation is correct, the heavier isotopes should have a larger decrease in Q{sub t} than the lighter mass nuclides due to the position of the Fermi surface in the i{sub 13/2} subshell. Indeed, {sup 160}Yb does not show a clear decrease in Q{sub t} at high spin. No high spin lifetime information exists for {sup 162}Yb, thus this experiment fills the gap of measured Q{sub t}`s in the light Yb series. The data is currently being analyzed.

  1. High Spin States in ^24Mg

    Science.gov (United States)

    Schwartz, J.; Lister, C. J.; Wuosmaa, A.; Betts, R. R.; Blumenthal, D.; Carpenter, M. P.; Davids, C. N.; Fischer, S. M.; Hackman, G.; Janssens, R. V. F.

    1996-05-01

    The ^12C(^16O,α)^24Mg reaction was used at 51.5MeV to populate high angular momentum states in ^24Mg. Gamma-rays de-exciting high spin states were detected in a 20 detector spectrometer (the AYE-ball) triggered by the ANL Fragment Mass Analyser (FMA). Channel selection, through detection of ^24Mg nuclei with the appropriate time of flight, was excellent. All the known decays from high spin states were seen in a few hours, with the exception of the 5.04 MeV γ-decay of the J^π=9^- state at 16.904 MeV footnote A.E.Smith et al., Phys. Lett. \\underlineB176, (1986)292. which could not be confirmed. The potential of the technique for studying the radiative decay of states with very high spin in light nuclei will be discussed.

  2. Nonlinear localized flat-band modes with spin-orbit coupling

    Science.gov (United States)

    Gligorić, G.; Maluckov, A.; Hadžievski, Lj.; Flach, Sergej; Malomed, Boris A.

    2016-10-01

    We report the coexistence and properties of stable compact localized states (CLSs) and discrete solitons (DSs) for nonlinear spinor waves on a flat-band network with spin-orbit coupling (SOC). The system can be implemented by means of a binary Bose-Einstein condensate loaded in the corresponding optical lattice. In the linear limit, the SOC opens a minigap between flat and dispersive bands in the system's band-gap structure, and preserves the existence of CLSs at the flat-band frequency, simultaneously lowering their symmetry. Adding on-site cubic nonlinearity, the CLSs persist and remain available in an exact analytical form, with frequencies that are smoothly tuned into the minigap. Inside of the minigap, the CLS and DS families are stable in narrow areas adjacent to the FB. Deep inside the semi-infinite gap, both the CLSs and DSs are stable too.

  3. Spin structure in high energy processes: Proceedings

    Energy Technology Data Exchange (ETDEWEB)

    DePorcel, L.; Dunwoodie, C. [eds.

    1994-12-01

    This report contains papers as the following topics: Spin, Mass, and Symmetry; physics with polarized Z{sup 0}s; spin and precision electroweak physics; polarized electron sources; polarization phenomena in quantum chromodynamics; polarized lepton-nucleon scattering; polarized targets in high energy physics; spin dynamics in storage rings and linear accelerators; spin formalism and applications to new physics searches; precision electroweak physics at LEP; recent results on heavy flavor physics from LEP experiments using 1990--1992 data; precise measurement of the left-right cross section asymmetry in Z boson production by electron-positron collisions; preliminary results on heavy flavor physics at SLD; QCD tests with SLD and polarized beams; recent results from TRISTAN at KEK; recent B physics results from CLEO; searching for the H dibaryon at Brookhaven; recent results from the compton observatory; the spin structure of the deuteron; spin structure of the neutron ({sup 3}HE) and the Bjoerken sum rule; a consumer`s guide to lattice QCD results; top ten models constrained by b {yields} sy; a review of the Fermilab fixed target program; results from the D0 experiment; results from CDF at FNAL; quantum-mechanical suppression of bremsstrahlung; report from the ZEUS collaboration at HERA; physics from the first year of H1 at HERA, and hard diffraction. These papers have been cataloged separately elsewhere.

  4. Observation of monolayer valence band spin-orbit effect and induced quantum well states in MoX2

    Science.gov (United States)

    Alidoust, Nasser; Bian, Guang; Xu, Su-Yang; Sankar, Raman; Neupane, Madhab; Liu, Chang; Belopolski, Ilya; Qu, Dong-Xia; Denlinger, Jonathan D.; Chou, Fang-Cheng; Hasan, M. Zahid

    2014-08-01

    Transition metal dichalcogenides transition metal dichalcogenides have attracted much attention recently due to their potential applications in spintronics and photonics because of the indirect to direct band gap transition and the emergence of the spin-valley coupling phenomenon upon moving from the bulk to monolayer limit. Here, we report high-resolution angle-resolved photoemission spectroscopy on MoSe2 single crystals and monolayer films of MoS2 grown on highly ordered pyrolytic graphite substrate. Our experimental results resolve the Fermi surface trigonal warping of bulk MoSe2, and provide evidence for the critically important spin-orbit split valence bands of monolayer MoS2. Moreover, we systematically image the formation of quantum well states on the surfaces of these materials, and present a theoretical model to account for these experimental observations. Our findings provide important insights into future applications of transition metal dichalcogenides in nanoelectronics, spintronics and photonics devices as they critically depend on the spin-orbit physics of these materials.

  5. US Greenwich High School Band in China

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    <正>A 229-member Greenwich High School (GHS) Band of Connecticut,the U. S.,organized and sent by the Chinese Cultural Exchange of the U. S.,visited Beijing,Xi’an,Shanghai and Suzhou from April 13 to 24 at the invitation of the CPAFFC.

  6. Blocking Effect and Underlying Physics of Identical Bands of Normally Deformed Nuclei at Low Spin

    Institute of Scientific and Technical Information of China (English)

    金太浩; 赵正姬; 曾谨言

    1994-01-01

    In the particle-number-conserving treatment of the cranked shell model Hamiltonian (blocking effect being taken into account exactly), the calculated even-odd differences in moments of inertia show large variation and depend sensitively on the location and Coriolis response of the blocked levels. The moments of inertia of the 170Yb, 171Lu [404] 7/2, [402] 5/2, [514] 9/2 and 171Yb [512] 5/2, [633] 7/2 bands at low spin are calculated and the experimental data are reproduced very well. No free parameter was involved in the calculation. The reason of the discrepancy between the observed "identical bands" at low spin and the BCS prediction is discussed.

  7. The effect of spin-orbit coupling in band structure of few-layer graphene

    Energy Technology Data Exchange (ETDEWEB)

    Sahdan, Muhammad Fauzi, E-mail: sahdan89@yahoo.co.id; Darma, Yudi, E-mail: sahdan89@yahoo.co.id [Department of Physics, Institut Teknologi Bandung, Jalan Ganesa 10, Bandung 40132 (Indonesia)

    2014-03-24

    Topological insulators are electronic materials that have a bulk band gap like an ordinary insulator but have protected conducting states on their edge or surface. This can be happened due to spin-orbit coupling and time-reversal symmetry. Moreover, the edge current flows through their edge or surface depends on its spin orientation and also it is robust against non-magnetic impurities. Therefore, topological insulators are predicted to be useful ranging from spintronics to quantum computation. Graphene was first predicted to be the precursor of topological insulator by Kane-Mele. They developed a Hamiltonian model to describe the gap opening in graphene. In this work, we investigate the band structure of few-layer graphene by using this model with analytical approach. The results of our calculations show that the gap opening occurs at K and K’ point, not only in single layer, but also in bilayer and trilayer graphene.

  8. High spin states in stable nucleus 84Sr

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    High spin states of 84Sr were populated through the reaction 70Zn(18O,4n)84Sr at 75 MeV beam energy.Measurement of excitation function,γ-γ coincidences,directional correlation from oriented state (DCO) ratios and γ-transition intensities were performed using eight anticompton HPGe detectors and one planar HPGe detector.Based on the measured results,a new level scheme of 84Sr was established in which 12 new states and nearly 30 new γ-transitions were identified in the present work.The positive-parity states of the new level scheme were compared with the results from calculations in the framework of the projected shell model (PSM).One negative-parity band was extended to spin Iπ=19-and it can be found that in the high spin states,the γ-transition energies show the nature of signature staggering.The negative-parity band levels are in good agreement with deformed configuration-mixing shell model (DCM) calculations.

  9. High spin spectroscopy of 139Pr

    Indian Academy of Sciences (India)

    S Chanda; Sarmishtha Bhattacharyya; Tumpa Bhattacharjee; S S Ghugre; Swapan Kumar Basu; S Muralithar; R P Singh; B Mukherjee; R K Bhowmik; S N Ray

    2001-07-01

    The high spin states in = 80 139Pr have been investigated by in-beam -spectroscopic techniques following the reaction 130Te (14N, 5) reaction at = 75 MeV, using a gamma detector array, consisting of seven 23% compton-suppressed high purity germanium detectors and a multiplicity ball of fourteen bismuth germanate elements. Based on – coincidence data, the level scheme of 139Pr has been considerably extended up to 7.2 MeV excitation. Tentative spin-parity assignments are done for the newly proposed levels on the basis of the DCO ratios corresponding to strong gates and the available information from the earlier light ion experiments.

  10. High-spin structure of N{approx_equal}Z nuclei around the A=72 region

    Energy Technology Data Exchange (ETDEWEB)

    Kelsall, N.S. [Department of Physics, University of York, YO10 5DD, York (United Kingdom); Svensson, C.E. [Department of Physics, University of Guelph, Guelph, Ontario (Canada); Fischer, S. [Department of Physics, DePaul University, IL 60614, Chicago (United States); Appelbe, D.E. [CLRC Daresbury Laboratory, WA4 4AD (United Kingdom); Austin, R.A.E.; Cameron, J.A. [Department of Physics, McMaster University, Hamilton, Ontario (Canada); Balamuth, D.P. [Department of Physics and Astronomy, University of Pennsylvania, PA 19104 (United States); Ball, G.C.; Hodgson, D.F. [TRIUMF Laboratory, 4004 Westbrook Mall, VT 2AS, Vancouver, BC (Canada); Carpenter, M.P.; Janssens, R.V.F.; Jenkins, D.G.; Lister, C.J. [Physics Division, Argonne National Laboratory, IL 60439, Argonne (United States); Clark, R.M.; Cromaz, M.; Deleplanque, M.A.; Diamond, R.M.; Fallon, P.; Lane, G.J.; Macchiavelli, A.O. [Nuclear Science Division, Lawrence Berkeley National Laboratory, CA 94720, Berkeley (United States); O' Leary, C.D.; Sarantities, D.G.; Stephens, F.S.; Schmidt, D.C.; Seweryniak, D.; Vetter, K.; Waddington, J.C.; Wadsworth, R.; Ward, D.; Wilson, A.N.; Afanasjev, A.V.; Frauendorf, S.; Ragnarsson, I.

    2004-04-01

    High-spin states have been studied in {sup 72}Kr and {sup 72}Br using the {sup 40}Ca+{sup 40}Ca and {sup 36}Ar+{sup 40}Ca reactions at 164 and 145 MeV, respectively. The properties and configurations of the high-spin bands observed have been interpreted using unpaired cranked Nilsson-Strutinsky (CNS), and for {sup 72}Kr, paired cranked relativistic Hartree-Bogoliubov (CRHB) calculations. In {sup 72}Kr a new band has been identified that has the properties expected for the doubly aligned S-band configuration. In {sup 72}Br the previously known bands have been extended to higher spin. This has lead to a re-interpretation of the configurations. (orig.)

  11. Large spin splitting of metallic surface-state bands at adsorbate-modified gold/silicon surfaces.

    Science.gov (United States)

    Bondarenko, L V; Gruznev, D V; Yakovlev, A A; Tupchaya, A Y; Usachov, D; Vilkov, O; Fedorov, A; Vyalikh, D V; Eremeev, S V; Chulkov, E V; Zotov, A V; Saranin, A A

    2013-01-01

    Finding appropriate systems with a large spin splitting of metallic surface-state band which can be fabricated on silicon using routine technique is an essential step in combining Rashba-effect based spintronics with silicon technology. We have found that originally poor structural and electronic properties of the Au/Si(111) √3 x √3 surface can be substantially improved by adsorbing small amounts of suitable species (e.g., Tl, In, Na, Cs). The resultant surfaces exhibit a highly-ordered atomic structure and spin-split metallic surface-state band with a momentum splitting of up to 0.052 Å(-1) and an energy splitting of up to 190 meV at the Fermi level. The family of adsorbate-modified Au/Si(111) √3 x √3 surfaces, on the one hand, is thought to be a fascinating playground for exploring spin-splitting effects in the metal monolayers on a semiconductor and, on the other hand, expands greatly the list of material systems prospective for spintronics applications.

  12. High-spin Mn wheels.

    Science.gov (United States)

    Manoli, Maria; Prescimone, Alessandro; Bagai, Rashmi; Mishra, Abhudaya; Murugesu, Muralee; Parsons, Simon; Wernsdorfer, Wolfgang; Christou, George; Brechin, Euan K

    2007-08-20

    The syntheses, structures, and magnetic properties of the complexes [MnIV4MnIII10MnII2O2(OCH3)12(tmp)8(O2CCH3)10].3Et2O (1.3Et2O), [MnIV2MnIII18MnII2O6(OCH3)14(O2CCH3)16(tmp)8(HIm)2].2CH3OH (2.2CH3OH), and [MnIV2MnIII18MnII2O6(OCH3)14(O2CCH3)16(Br-mp)8(HIm)2].2C6H14.5CH3OH (3.2C6H14.5CH3OH) are reported. The unusual wheel-like complexes were prepared by the treatment of [Mn3O(O2CCH3)6(HIm)3](O2CCH3) (HIm = imidazole) with 1,1,1-tris-(hydroxymethyl)propane (H3tmp) (1 and 2) or 2-(bromomethyl)-2-(hydroxymethyl)-1,3-propanediol (Br-mpH3) (3) in the presence of sodium methoxide (NaOCH3, 2, and 3) in CH3OH. Complex 1.3Et2O crystallizes in the triclinic space group P, while complexes 2.2CH3OH and 3.2C6H14.5CH3OH crystallize in the orthorhombic space group Pbca. Direct current magnetic susceptibility data, collected for 1-3 in the respective 1.8-300 K and 0.1-7 T temperature and magnetic-field ranges, afford spin ground-state values of S = 14 +/- 1 for complex 1 and S = 9 +/- 1 for complexes 2 and 3. Alternating current susceptibility measurements performed on all three complexes in the 1.8-10 K temperature range in a 3.5 G oscillating field at frequencies between 50 and 1000 Hz reveal out-of-phase chi"M signals below approximately 3 K. Single-crystal hysteresis loop and relaxation measurements confirm single-molecule magnetism behavior.

  13. Band-structure-dependent nonlinear giant magnetoresistance in Ni1-xFex dual spin valves

    Science.gov (United States)

    Banerjee, N.; Robinson, J. W. A.; Aziz, A.; Ali, M.; Hickey, B. J.; Blamire, M. G.

    2012-10-01

    Conventional giant magnetoresistance (GMR) in spin valves is current-independent, so the resistance of a device depends only on the relative orientation of the magnetic layers. In dual spin valves consisting of three ferromagnetic (FM) layers separated by nonmagnetic (NM) spacers (i.e., a FM1/NM/FM2/NM/FM1), GMR can be current-dependent if spin can accumulate in FM2 when outer FM1 layers are aligned antiparallel. Currently the underlying physics is poorly understood, although spin accumulation in FM2 is likely to depend on the gradient in the density of states at the Fermi energy of the ferromagnet. To investigate this hypothesis, we have measured a series of dual spin valves with Ni1-xFex as FM2 layers of varying composition. We show that both the magnitude and sign of the nonlinear GMR depend strongly on the Fe content and thus on the band structure of the ferromagnet FM2.

  14. High spin rate magnetic controller for nanosatellites

    Science.gov (United States)

    Slavinskis, A.; Kvell, U.; Kulu, E.; Sünter, I.; Kuuste, H.; Lätt, S.; Voormansik, K.; Noorma, M.

    2014-02-01

    This paper presents a study of a high rate closed-loop spin controller that uses only electromagnetic coils as actuators. The controller is able to perform spin rate control and simultaneously align the spin axis with the Earth's inertial reference frame. It is implemented, optimised and simulated for a 1-unit CubeSat ESTCube-1 to fulfil its mission requirements: spin the satellite up to 360 deg s-1 around the z-axis and align its spin axis with the Earth's polar axis with a pointing error of less than 3°. The attitude of the satellite is determined using a magnetic field vector, a Sun vector and angular velocity. It is estimated using an Unscented Kalman Filter and controlled using three electromagnetic coils. The algorithm is tested in a simulation environment that includes models of space environment and environmental disturbances, sensor and actuator emulation, attitude estimation, and a model to simulate the time delay caused by on-board calculations. In addition to the normal operation mode, analyses of reduced satellite functionality are performed: significant errors of attitude estimation due to non-operational Sun sensors; and limited actuator functionality due to two non-operational coils. A hardware-in-the-loop test is also performed to verify on-board software.

  15. High spin levels in /sup 151/Ho

    Energy Technology Data Exchange (ETDEWEB)

    Gizon, J.; Gizon, A.; Andre, S.; Genevey, J.; Jastrzebski, J.; Kossakowski, R.; Moszynski, M.; Preibisz, Z.

    1981-07-01

    We report here on the first study of the level structure of /sup 151/Ho. High spin levels in /sup 151/Ho have been populated in the /sup 141/Pr + /sup 16/O and /sup 144/Sm + /sup 12/C reactions. The level structure has been established up to 6,6 MeV energy and the spins and parities determined up to 49/2/sup -/. Most of the proposed level configurations can be explained by the coupling of h sub(11/2) protons to fsub(7/2) and/or hsub(9/2) neutrons. An isomer with 14 +- 3 ns half-life and a delayed gamma multiplicity equal to 17 +- 2 has been found. Its spin is larger than 57/2 h units.

  16. High spin levels in /sup 151/Ho

    Energy Technology Data Exchange (ETDEWEB)

    Gizon, J.; Gizon, A.; Andre, S.; Genevey, J.; Jastrzebski, J.; Kossakowski, R.; Moszynski, M.; Preibisz, Z.

    1981-07-01

    We report here on the first study of the level structure of /sup 151/Ho. High spin levels in /sup 151/Ho have been populated in the /sup 141/Pr + /sup 16/O and /sup 144/Sm + /sup 12/C reactions. The level structure has been established up to 6.6 MeV energy and the spins and parities determined up to 49/2/sup -/. Most of the proposed level configurations can be explained by the coupling of hsub(11/2) protons to fsub(7/2) and/or hsub(9/2) neutrons. An isomer with 14 +- 3 ns half-life and a delayed gamma multiplicity equal 17 +- 2 has been found. Its spin is larger than 57/2 h units.

  17. HIGH-SPIN STATES IN EU-148

    NARCIS (Netherlands)

    JONGMAN, [No Value; BACELAR, JCS; BALANDA, A; NOORMAN, RF; STEENBERGEN, T; DEVOIGT, MJA; NYBERG, J; SLETTEN, G; DIONISIO, J; VIEU, C; LAGRANGE, JM; PAUTRAT, M; Urban, W

    1995-01-01

    High-spin states in the odd-odd nucleus Eu-148, populated by a carbon-13 induced reaction on a lanthanum target, were investigated with several different tools of in-beam nuclear spectroscopy. The low-energy levels show collective excitations, interpreted as 3- octupole-phonon couplings to multi-par

  18. High-spin states in 128I

    Institute of Scientific and Technical Information of China (English)

    ZHENG Yun; ZHU Li-Hua; WU Xiao-Guang; LI Guang-Sheng; HAO Xin; WANG Lie-Lin; HE Chuang-Ye; LIU Ying; LI Xue-Qin; PAN Bo; WANG Lei; LI Zhong-Yu; DING Huai-Bo

    2009-01-01

    The high-spin states in 128I have been studied by using in-beam γ-ray spectroscopy with the 124Sn(7Li,3n)128I reaction at beam energies of 25, 28 and 42 MeV. A new level scheme including 20 new levels and 27 new γ-transitions for 128I has been established preliminarily.

  19. Structure change of 156Yb at high-spin states

    Institute of Scientific and Technical Information of China (English)

    HUA Hui; LI Zhong-Yu; WANG Shou-Yu; MENG Jie; LI Zhi-Huan; LI Xiang-Qing; XU Fu-Rong; LIU Hong-Liang; ZHANG Shuang-Quan; ZHOU Shan-Gui; YE Yan-Lin; JIANG Dong-Xing; ZHENG Tao; ZHU Li-Hua; WU Xiao-Guang; LI Guang-Sheng; HE Chuang-Ye; MA Li-Ying; LU Fei; FAN Feng-Ying; HAN Li-Ying; WANG He; XIAO Jun; LI Xue-Qin; CHEN Dong; FANG Xiao; LOU Jian-Lin; LIU Ying; HAO Xin; PAN Bo; LI Li-Hua

    2009-01-01

    High-spin states of 156Yb have been studied via the 144Sm(16O,4n)156Yb fusion-evaporation reaction at beam energy 102 MeV. The positive-parity yrast band and negative-parity cascade have been extended up to higher-spin states, respectively. The characteristics of the negative-parity sequence above the 25- state may related to the excitation from the nucleon in the Z = 64, N = 82 core. The E-GOS curve for the positive-parity yrast sequence in 156Yb indicate that this nucleus may undergo an evolution from quasivibrational to quasirotational structure with increasing angular momentum. The Cranked Woods-Saxon-Strutinsky calculations by means of Total-Routhian-Surface (TRS) methods has been made to understand this structure change.

  20. Entanglement between low- and high-lying atomic spin waves

    Science.gov (United States)

    Ding, D. S.; Wang, K.; Zhang, W.; Shi, S.; Dong, M. X.; Yu, Y. C.; Zhou, Z. Y.; Shi, B. S.; Guo, G. C.

    2016-11-01

    Establishing a quantum interface between different physical systems is of special importance for developing the practical versatile quantum networks. Entanglement between low- and high-lying atomic spin waves is essential for building up Rydberg-based quantum information engineering, which is also helpful to study the dynamics behavior of entanglement under external perturbations. Here, we report on the successful storage of a single photon as a high-lying atomic spin wave in a quantum regime. By storing a K-vector entanglement between a single photon and low-lying spin wave, we experimentally realize the entanglement between low- and high-lying atomic spin waves in two separated atomic systems. This makes our experiment a primary demonstration of Rydberg quantum memory of entanglement, representing a primary step toward the construction of a hybrid quantum interface.

  1. Orbital mapping of energy bands and the truncated spin polarization in three-dimensional Rashba semiconductors

    Science.gov (United States)

    Liu, Qihang; Zhang, Xiuwen; Waugh, J. A.; Dessau, D. S.; Zunger, Alex

    2016-09-01

    Associated with spin-orbit coupling (SOC) and inversion symmetry breaking, Rashba spin polarization opens an avenue for spintronic applications that was previously limited to ordinary magnets. However, spin-polarization effects in actual Rashba systems are far more complicated than what conventional single-orbital models would suggest. By studying via density functional theory and a multiorbital k .p model a three-dimensional bulk Rashba system (free of complications by surface effects), BiTeI, we find that the physical origin of the leading spin-polarization effects is SOC-induced hybridization between spin and multiple orbitals, especially those with nonzero orbital angular momenta. In this framework we establish a general understanding of the orbital mapping, common to the surface of topological insulators and the Rashba system. Consequently, the intrinsic mechanism of various spin-polarization effects—which pertain to all Rashba systems, even those with global inversion symmetry—is understood as a manifestation of the orbital textures. This finding suggests a route for designing high-spin-polarization materials by considering the atomic-orbital content.

  2. Spin Transport in High-Quality Suspended Graphene Devices

    NARCIS (Netherlands)

    Guimaraes, Marcos H. D.; Veligura, A.; Zomer, P. J.; Maassen, T.; Vera-Marun, I. J.; Tombros, N.; van Arees, B. J.; Wees, B.J. van

    2012-01-01

    We measure spin transport in high mobility suspended graphene (mu approximate to 10(5)cm(2)/(V s)), obtaining a (spin) diffusion coefficient of 0.1 m(2)/s and giving a lower bound on the spin relaxation time (tau(s) approximate to 150 ps) and spin relaxation length (lambda(s) = 4.7 mu m) for intrins

  3. Spin drift in highly doped n-type Si

    Science.gov (United States)

    Kameno, Makoto; Ando, Yuichiro; Shinjo, Teruya; Koike, Hayato; Sasaki, Tomoyuki; Oikawa, Tohru; Suzuki, Toshio; Shiraishi, Masashi

    2014-03-01

    A quantitative estimation of spin drift velocity in highly doped n-type silicon (Si) at 8 K is presented in this letter. A local two-terminal Hanle measurement enables the detection of a modulation of spin signals from the Si as a function of an external electric field, and this modulation is analyzed by using a spin drift-diffusion equation and an analytical solution of the Hanle-type spin precession. The analyses reveal that the spin drift velocity is linearly proportional to the electric field. The contribution of the spin drift effect to the spin signals is crosschecked by introducing a modified nonlocal four-terminal method.

  4. Spin drift in highly doped n-type Si

    Energy Technology Data Exchange (ETDEWEB)

    Kameno, Makoto; Ando, Yuichiro; Shinjo, Teruya [Graduate School of Engineering Science, Osaka University Osaka (Japan); Koike, Hayato; Sasaki, Tomoyuki; Oikawa, Tohru [Advanced Technology Development Center, TDK Cooperation, Chiba (Japan); Suzuki, Toshio [AIT, Akita Research Institute of Advanced Technology, Akita (Japan); Shiraishi, Masashi, E-mail: mshiraishi@kuee.kyoto-u.ac.jp [Graduate School of Engineering Science, Osaka University Osaka (Japan); Graduate School of Engineering, Kyoto University, Kyoto (Japan)

    2014-03-03

    A quantitative estimation of spin drift velocity in highly doped n-type silicon (Si) at 8 K is presented in this letter. A local two-terminal Hanle measurement enables the detection of a modulation of spin signals from the Si as a function of an external electric field, and this modulation is analyzed by using a spin drift-diffusion equation and an analytical solution of the Hanle-type spin precession. The analyses reveal that the spin drift velocity is linearly proportional to the electric field. The contribution of the spin drift effect to the spin signals is crosschecked by introducing a modified nonlocal four-terminal method.

  5. Dynamical Mean-Field Theory Plus Numerical Renormalization-Group Study of Spin-Orbital Separation in a Three-Band Hund Metal.

    Science.gov (United States)

    Stadler, K M; Yin, Z P; von Delft, J; Kotliar, G; Weichselbaum, A

    2015-09-25

    We show that the numerical renormalization group is a viable multi-band impurity solver for dynamical mean-field theory (DMFT), offering unprecedented real-frequency spectral resolution at arbitrarily low energies and temperatures. We use it to obtain a numerically exact DMFT solution to the Hund metal problem for a three-band model on a Bethe lattice at 1/3 filling. The ground state is a Fermi liquid. The one-particle spectral function undergoes a coherence-incoherence crossover with increasing temperature, with spectral weight being transferred from low to high energies. Further, it exhibits a strong particle-hole asymmetry. In the incoherent regime, the self-energy displays approximate power-law behavior for positive frequencies only. The spin and orbital spectral functions show "spin-orbital separation": spin screening occurs at much lower energies than orbital screening. The renormalization group flows clearly reveal the relevant physics at all energy scales.

  6. High spin spectroscopy in 34Cl

    Science.gov (United States)

    Bisoi, Abhijit; Sarkar, M. Saha; Sarkar, S.; Ray, S.; Pramanik, D.; Kshetri, R.; Nag, Somnath; Selvakumar, K.; Singh, P.; Goswami, A.; Saha, S.; Sethi, J.; Trivedi, T.; Naidu, B. S.; Donthi, R.; Nanal, V.; Palit, R.

    2014-02-01

    High spin states of 34Cl populated through 27Al(12C,αn)34Cl reaction at E(12C)=40 MeV, have been studied using the Indian National Gamma Array facility. The level scheme has been extended up to 10.6 MeV utilizing the results of intensity, directional correlation, and linear polarization measurements. Lifetimes of a few excited states have been estimated for the first time using the Doppler shift attenuation method. Large-basis shell-model calculations within the sd-pf space have been done to understand the microscopic origin of the excited states. Involvement of pf orbitals have been found to be essential to reproduce the negative-parity as well as high spin positive-parity states. Onset of collectivity manifested through short half-lives and large B (E2) values have been reproduced well in the calculations.

  7. High power evaluation of X-band high power loads

    CERN Document Server

    Matsumoto, Shuji; Syratchev, Igor; Riddone, Germana; Wuensch, Walter

    2010-01-01

    Several types of X-band high power loads developed for several tens of MW range were designed, fabricated and used for high power tests at X-band facility of KEK. Some of them have been used for many years and few units showed possible deterioration of RF performance. Recently revised-design loads were made by CERN and the high power evaluation was performed at KEK. In this paper, the main requirements are recalled, together with the design features. The high power test results are analysed and presented

  8. Spin- and valley-dependent electronic band structure and electronic heat capacity of ferromagnetic silicene in the presence of strain, exchange field and Rashba spin-orbit coupling

    Science.gov (United States)

    Hoi, Bui Dinh; Yarmohammadi, Mohsen; Kazzaz, Houshang Araghi

    2017-10-01

    We studied how the strain, induced exchange field and extrinsic Rashba spin-orbit coupling (RSOC) enhance the electronic band structure (EBS) and electronic heat capacity (EHC) of ferromagnetic silicene in presence of external electric field (EF) by using the Kane-Mele Hamiltonian, Dirac cone approximation and the Green's function approach. Particular attention is paid to investigate the EHC of spin-up and spin-down bands at Dirac K and K‧ points. We have varied the EF, strain, exchange field and RSOC to tune the energy of inter-band transitions and consequently EHC, leading to very promising features for future applications. Evaluation of EF exhibits three phases: Topological insulator (TI), valley-spin polarized metal (VSPM) and band insulator (BI) at given aforementioned parameters. As a new finding, we have found a quantum anomalous Hall phase in BI regime at strong RSOCs. Interestingly, the effective mass of carriers changes with strain, resulting in EHC behaviors. Here, exchange field has the same behavior with EF. Finally, we have confirmed the reported and expected symmetry results for both Dirac points and spins with the study of valley-dependent EHC.

  9. High-spin structure in 40K

    Science.gov (United States)

    Söderström, P.-A.; Recchia, F.; Nyberg, J.; Gadea, A.; Lenzi, S. M.; Poves, A.; Ataç, A.; Aydin, S.; Bazzacco, D.; Bednarczyk, P.; Bellato, M.; Birkenbach, B.; Bortolato, D.; Boston, A. J.; Boston, H. C.; Bruyneel, B.; Bucurescu, D.; Calore, E.; Cederwall, B.; Charles, L.; Chavas, J.; Colosimo, S.; Crespi, F. C. L.; Cullen, D. M.; de Angelis, G.; Désesquelles, P.; Dosme, N.; Duchêne, G.; Eberth, J.; Farnea, E.; Filmer, F.; Görgen, A.; Gottardo, A.; Grębosz, J.; Gulmini, M.; Hess, H.; Hughes, T. A.; Jaworski, G.; Jolie, J.; Joshi, P.; Judson, D. S.; Jungclaus, A.; Karkour, N.; Karolak, M.; Kempley, R. S.; Khaplanov, A.; Korten, W.; Ljungvall, J.; Lunardi, S.; Maj, A.; Maron, G.; Męczyński, W.; Menegazzo, R.; Mengoni, D.; Michelagnoli, C.; Molini, P.; Napoli, D. R.; Nolan, P. J.; Norman, M.; Obertelli, A.; Podolyak, Zs.; Pullia, A.; Quintana, B.; Redon, N.; Regan, P. H.; Reiter, P.; Robinson, A. P.; Şahin, E.; Simpson, J.; Salsac, M. D.; Smith, J. F.; Stézowski, O.; Theisen, Ch.; Tonev, D.; Unsworth, C.; Ur, C. A.; Valiente-Dobón, J. J.; Wiens, A.

    2012-11-01

    High-spin states of 40K have been populated in the fusion-evaporation reaction 12C(30Si,np)40K and studied by means of γ-ray spectroscopy techniques using one triple-cluster detector of the Advanced Gamma Tracking Array at the Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali di Legnaro. Several states with excitation energy up to 8 MeV and spin up to 10- have been discovered. These states are discussed in terms of J=3 and T=0 neutron-proton hole pairs. Shell-model calculations in a large model space have shown good agreement with the experimental data for most of the energy levels. The evolution of the structure of this nucleus is here studied as a function of excitation energy and angular momentum.

  10. High-spin structure in $^{40}$K

    CERN Document Server

    Söderström, P -A; Nyberg, J; Gadea, A; Lenzi, S M; Poves, A; Ataç, A; Aydin, S; Bazzacco, D; Bednarczyk, P; Bellato, M; Birkenbach, B; Bortolato, D; Boston, A J; Boston, H C; Bruyneel, B; Bucurescu, D; Calore, E; Cederwall, B; Charles, L; Chavas, J; Colosimo, S; Crespi, F C L; Cullen, D M; de Angelis, G; Désesquelles, P; Dosme, N; Duchêne, G; Eberth, J; Farnea, E; Filmer, F; Görgen, A; Gottardo, A; Grębosz, J; Gulmini, M; Hess, H; Hughes, T A; Jaworski, G; Jolie, J; Joshi, P; Judson, D S; Jungclaus, A; Karkour, N; Karolak, M; Kempley, R S; Khaplanov, A; Korten, W; Ljungvall, J; Lunardi, S; Maj, A; Maron, G; Męczyński, W; Mengoni, D; Michelagnoli, C; Molini, P; Napoli, D R; Nolan, P J; Norman, M; Obertelli, A; Podolyak, Zs; Pullia, A; Quintana, B; Redon, N; Regan, P H; Reiter, P; Robinson, A P; Şahin, E; Simpson, J; Salsac, M D; Smith, J F; Stézowski, O; Theisen, Ch; Tonev, D; Unsworth, C; Ur, C A; Valiente-Dobón, J J; Wiens, A

    2012-01-01

    High-spin states of $^{40}$K have been populated in the fusion-evaporation reaction $^{12}$C($^{30}$Si,np)$^{40}$K and studied by means of $\\gamma$-ray spectroscopy techniques using one AGATA triple cluster detector, at INFN - Laboratori Nazionali di Legnaro. Several new states with excitation energy up to 8 MeV and spin up to $10^-$ have been discovered. These new states are discussed in terms of J=3 and T=0 neutron-proton hole pairs. Shell-model calculations in a large model space have shown a good agreement with the experimental data for most of the energy levels. The evolution of the structure of this nucleus is here studied as a function of excitation energy and angular momentum.

  11. Complex band structures of transition metal dichalcogenide monolayers with spin-orbit coupling effects

    Science.gov (United States)

    Szczęśniak, Dominik; Ennaoui, Ahmed; Ahzi, Saïd

    2016-09-01

    Recently, the transition metal dichalcogenides have attracted renewed attention due to the potential use of their low-dimensional forms in both nano- and opto-electronics. In such applications, the electronic and transport properties of monolayer transition metal dichalcogenides play a pivotal role. The present paper provides a new insight into these essential properties by studying the complex band structures of popular transition metal dichalcogenide monolayers (MX 2, where M  =  Mo, W; X  =  S, Se, Te) while including spin-orbit coupling effects. The conducted symmetry-based tight-binding calculations show that the analytical continuation from the real band structures to the complex momentum space leads to nonlinear generalized eigenvalue problems. Herein an efficient method for solving such a class of nonlinear problems is presented and yields a complete set of physically relevant eigenvalues. Solutions obtained by this method are characterized and classified into propagating and evanescent states, where the latter states manifest not only monotonic but also oscillatory decay character. It is observed that some of the oscillatory evanescent states create characteristic complex loops at the direct band gap of MX 2 monolayers, where electrons can directly tunnel between the band gap edges. To describe these tunneling currents, decay behavior of electronic states in the forbidden energy region is elucidated and their importance within the ballistic transport regime is briefly discussed.

  12. 16th Workshop on High Energy Spin Physics

    CERN Document Server

    2016-01-01

    The Workshop will cover a wide range of spin phenomena at high and intermediate energies such as: recent experimental data on spin physics the nucleon spin structure and GPD's spin physics and QCD spin physics in the Standard Model and beyond T-odd spin effects polarization and heavy ion physics spin in gravity and astrophysics the future spin physics facilities spin physics at NICA polarimeters for high energy polarized beams acceleration and storage of polarized beams the new polarization technology related subjects The Workshop will be held in the Bogoliubov Laboratory of Theoretical Physics of the Joint Institute for Nuclear Research, 141980 Dubna, Moscow Region, Russia. The program of the workshop will include plenary and parallel (if necessary) sessions. Plenary sessions will be held in the Conference Hall. Parallel sections will take place in the same building. There will be invited talks (up to 40 min) and original reports (20 min). The invited speakers will present new experimental and theoretical re...

  13. High-energy band structure of gold

    DEFF Research Database (Denmark)

    Christensen, N. Egede

    1976-01-01

    The band structure of gold for energies far above the Fermi level has been calculated using the relativistic augmented-plane-wave method. The calculated f-band edge (Γ6-) lies 15.6 eV above the Fermi level is agreement with recent photoemission work. The band model is applied to interpret...

  14. Studies of magnetostriction and spin polarized band structures of rare earth intermetallics

    Science.gov (United States)

    Wallace, W. E.

    1979-01-01

    Anisotropic magnetostriction measurements of R6Fe23, R = (Tb, Dy, Ho, and Er) were carried out from 77 K to room temperature. Magnetic fields up to 2.1 Tesla were applied. All the compounds exhibited large magnetostrictions at 77 K, the largest effect being obtained for Tb6Fe23. Saturation magnetostriction values for the compounds were also determined for 77 K and room temperature. Results of the temperature dependence of magnetostriction for Er6Fe23 are in good agreement with Callen and Callen's single ion theory. Therefore, the main sources of magnetostriction in this compound is the Er ion. The spin-up and spin-down electronic energy bands, the density of states and the magnetic moments of YCo5, SmCo5, and GdCo5 were calculated by the spin polarized augmented plane wave technique. The calculations obtained show the origin of the moment, provide good estimates of its magnitude and variation, and the reasons for those variations. They also show the important role of partial charge transfer and of d-d electronic coupling. Calculations for LaNi5 and GdNi5 systems are discussed.

  15. Microscopic description of rotation: From ground states to the extremes of ultra-high spin

    CERN Document Server

    Afanasjev, A V

    2013-01-01

    Recent progress in the microscopic description of rotational properties within covariant density functional theory (CDFT) is presented. It is shown that it provides an accurate description of rotational bands both in the paired regime at low spin and in the unpaired regime at ultra-high spins. The predictive power of CDFT is verified by comparing the CDFT predictions for band crossing features in the $A\\geq 242$ actinides with new experimental data. In addition, possible role of the Coulomb antipairing effect for proton pairing is discussed.

  16. Identification of Bandhead Spin and Identical Bands for Odd-A Nuclei in A ~ 190 Superdeforrned Mass Region

    Institute of Scientific and Technical Information of China (English)

    A.S. Shalaby

    2004-01-01

    The dynamical moment of inertia is estimated with its even-power expansion of the rotational frequency and in accordance we determine the intermediate spins of the superdeformed (SD) rotational bands. Using Marquardt method of nonlinear least-squares routines, we determine the expansion coefficients by fitting the proposed dynamical moment of inertia with its recent experimental data of the SD nuclei in the A=190 mass region. The comparison between our theoretical and available experimental data for the dynamic moment of inertia and spin shows good agreements.Also, we have calculated the static moment of inertia at three alternative values of spin. The value of spin at which the two moments of inertia are nearly equals is to be regarded as a bandhead spin of the corresponding band. These studies are carried out for eighteen bands of odd-A nuclei of the superdeformed region 190, namely 189Hg(b1), 191 Hg(b1, b2,b3, b4), 193Hg(b2, b3, b5), 195Hg(b1, b2, b3, b4), 193Tl(b1, b2, b3, b5), 189Tl(b1), and 197Bi(b1). We also notice the occurrence of identical SD bands with near identical transition energies among the considered SD bands.

  17. High spin-filter efficiency and Seebeck effect through spin-crossover iron-benzene complex

    Science.gov (United States)

    Yan, Qiang; Zhou, Liping; Cheng, Jue-Fei; Wen, Zhongqian; Han, Qin; Wang, Xue-Feng

    2016-04-01

    Electronic structures and coherent quantum transport properties are explored for spin-crossover molecule iron-benzene Fe(Bz)2 using density functional theory combined with non-equilibrium Green's function. High- and low-spin states are investigated for two different lead-molecule junctions. It is found that the asymmetrical T-shaped contact junction in the high-spin state behaves as an efficient spin filter while it has a smaller conductivity than that in the low-spin state. Large spin Seebeck effect is also observed in asymmetrical T-shaped junction. Spin-polarized properties are absent in the symmetrical H-shaped junction. These findings strongly suggest that both the electronic and contact configurations play significant roles in molecular devices and metal-benzene complexes are promising materials for spintronics and thermo-spintronics.

  18. High Efficiency Ka-Band Spatial Combiner

    Directory of Open Access Journals (Sweden)

    D. Passi

    2014-12-01

    Full Text Available A Ka-Band, High Efficiency, Small Size Spatial Combiner (SPC is proposed in this paper, which uses an innovatively matched quadruple Fin Lines to microstrip (FLuS transitions. At the date of this paper and at the Author's best knowledge no such FLuS innovative transitions have been reported in literature before. These transitions are inserted into a WR28 waveguide T-junction, in order to allow the integration of 16 Monolithic Microwave Integrated Circuit (MMIC Solid State Power Amplifiers (SSPA's. A computational electromagnetic model using the finite elements method has been implemented. A mean insertion loss of 2 dB is achieved with a return loss better the 10 dB in the 31-37 GHz bandwidth.

  19. Spin, quadrupole moment, and deformation of the magnetic-rotational band head in (193)Pb

    CERN Document Server

    Balabanski, D L; Iordachescu, A; Bazzacco, D; Brandolini, F; Bucurescu, D; Chmel, S; Danchev, M; De Poli, M; Georgiev, G; Haas, H; Hubel, H; Marginean, N; Menegazzo, R; Neyens, G; Pavan, P; Rossi Alvarez, C; Ur, C A; Vyvey, K; Frauendorf, S

    2011-01-01

    The spectroscopic quadrupole moment of the T(1/2) = 9.4(5) ns isomer in (193)Pb at an excitation energy E(ex) = (2585 + x) keV is measured by the time-differential perturbed angular distribution method as vertical bar Q(s)vertical bar = 2.6(3) e b. Spin and parity I(pi) = 27/2(-) are assigned to it based on angular distribution measurements. This state is the band head of a magnetic-rotational band, described by the coupling of a neutron hole in the 1i(13/2) subshell with the (3s(1/2)(-2)1h(9/2)1i(13/2))(11-) proton excitation. The pairing-plus-quadrupole tilted-axis cranking calculations reproduce the measured quadrupole moment with a moderate oblate deformation epsilon(2) = -0.11, similar to that of the 11(-)proton intruder states, which occur in the even-even Pb nuclei in the region. This is the first direct measurement of a quadrupole moment and thus of the deformation of a magnetic-rotational band head.

  20. CdSe/CdTe interface band gaps and band offsets calculated using spin-orbit and self-energy corrections

    Energy Technology Data Exchange (ETDEWEB)

    Ribeiro, M. [Centro de Pesquisas Avancadas Wernher von Braun, Av. Alice de Castro P.N. Mattosinho 301, CEP 13098-392 Campinas, SP (Brazil); Ferreira, L.G. [Departamento de Fisica dos Materiais e Mecanica, Instituto de Fisica, Universidade de Sao Paulo, 05315-970 Sao Paulo, SP (Brazil); Fonseca, L.R.C. [Center for Semiconductor Components, State University of Campinas, R. Pandia Calogeras 90, 13083-870 Campinas, SP (Brazil); Ramprasad, R. [Department of Chemical, Materials and Biomolecular Engineering, Institute of Materials Science, University of Connecticut, 97 North Eagleville Road, Storrs, CT 06269 (United States)

    2012-09-20

    We performed ab initio calculations of the electronic structures of bulk CdSe and CdTe, and their interface band alignments on the CdSe in-plane lattice parameters. For this, we employed the LDA-1/2 self-energy correction scheme to obtain corrected band gaps and band offsets. Our calculations include the spin-orbit effects for the bulk cases, which have shown to be of importance for the equilibrium systems and are possibly degraded in these strained semiconductors. Therefore, the SO showed reduced importance for the band alignment of this particular system. Moreover, the electronic structure calculated along the transition region across the CdSe/CdTe interface shows an interesting non-monotonic variation of the band gap in the range 0.8-1.8 eV, which may enhance the absorption of light for corresponding frequencies at the interface between these two materials in photovoltaic applications.

  1. High spin polarization and the origin of unique ferromagnetic ground state in CuFeSb

    Science.gov (United States)

    Sirohi, Anshu; Singh, Chandan K.; Thakur, Gohil S.; Saha, Preetha; Gayen, Sirshendu; Gaurav, Abhishek; Jyotsna, Shubhra; Haque, Zeba; Gupta, L. C.; Kabir, Mukul; Ganguli, Ashok K.; Sheet, Goutam

    2016-06-01

    CuFeSb is isostructural to the ferro-pnictide and chalcogenide superconductors and it is one of the few materials in the family that are known to stabilize in a ferromagnetic ground state. Majority of the members of this family are either superconductors or antiferromagnets. Therefore, CuFeSb may be used as an ideal source of spin polarized current in spin-transport devices involving pnictide and the chalcogenide superconductors. However, for that the Fermi surface of CuFeSb needs to be sufficiently spin polarized. In this paper we report direct measurement of transport spin polarization in CuFeSb by spin-resolved Andreev reflection spectroscopy. From a number of measurements using multiple superconducting tips we found that the intrinsic transport spin polarization in CuFeSb is high (˜47%). In order to understand the unique ground state of CuFeSb and the origin of large spin polarization at the Fermi level, we have evaluated the spin-polarized band structure of CuFeSb through first principles calculations. Apart from supporting the observed 47% transport spin polarization, such calculations also indicate that the Sb-Fe-Sb angles and the height of Sb from the Fe plane are strikingly different for CuFeSb than the equivalent parameters in other members of the same family thereby explaining the origin of the unique ground state of CuFeSb.

  2. STUDY OF HIGH-SPIN STATES IN EU-150 AND EU-151

    NARCIS (Netherlands)

    JONGMAN, [No Value; BACELAR, JCS; VANPOL, J; NYBERG, J; SLETTEN, G; DIONISIO, JS; VIEU, C; LAGRANGE, JM; PAUTRAT, M; Urban, W

    1995-01-01

    High-spin states in Eu-150,Eu-151 were populated by the Xe-136(F-19, xn)Eu-155-xn reaction. Extensive e gamma-, gamma gamma-measurements led to new level schemes of Eu-150,Eu-151. Most observed excitations are interpreted as quasi-rotational bands built on top of multi-p-h states. Enhanced E1 decays

  3. A Theoretical Structure of High School Concert Band Performance

    Science.gov (United States)

    Bergee, Martin J.

    2015-01-01

    This study used exploratory (EFA) and confirmatory factor analysis (CFA) to verify a theoretical structure for high school concert band performance and to test that structure for viability, generality, and invariance. A total of 101 university students enrolled in two different bands rated two high school band performances (a "first"…

  4. High power Ka band TWT amplifier

    Energy Technology Data Exchange (ETDEWEB)

    Golkowski, C.; Ivers, J.D.; Nation, J.A.; Wang, P.; Schachter, L.

    1999-07-01

    Two high power 35 GHz TWT amplifiers driven by a relativistic pencil, 850 kV, 200A electron beam have been assembled and tested. The first had a dielectric slow wave structure and was primarily used to develop diagnostics, and to gain experience in working with high power systems in Ka band. The source of the input power for the amplifier was a magnetron producing a 30 kW, 200ns long pulse of which 10 kW as delivered to the experiment. The 30 cm long dielectric (Teflon) amplifier produced output power levels of about 1 MW with a gain of about 23 dB. These results are consistent with expectations from PIC code simulations for this arrangement. The second amplifier, which is a single stage disk loaded slow wave structure, has been designed. It consists of one hundred uniform cells with two sets of ten tapered calls at the ends to lower the reflection coefficient. The phase advance per cell is {pi}/2. The amplifier passband extends from 28 to 40 GHz. It is designed to increase the output power to about 20 MW. The amplifier is in construction and will be tested in the near future. Details of the design of both systems will be provided and initial results from the new amplifier presented.

  5. High-temperature MAS-NMR at high spinning speeds.

    Science.gov (United States)

    Kirchhain, Holger; Holzinger, Julian; Mainka, Adrian; Spörhase, Andreas; Venkatachalam, Sabarinathan; Wixforth, Achim; van Wüllen, Leo

    2016-09-01

    A low cost version to enable high temperature MAS NMR experiments at temperatures of up to 700°C and spinning speeds of up to 10kHz is presented. The method relies on inductive heating using a metal coated rotor insert. The metal coating is accomplished via a two step process involving physical vapor deposition and galvanization.

  6. Spin injection into high temperature superconductor

    CERN Document Server

    Severac, C H L

    2000-01-01

    DELTA M versus pulse length was measured. It showed two regions: above 100 mu s DELTA M is the same for both magnetic and non-magnetic material and can be attributed to heating. Below 100 mu s, DELTA M is only significant for the CMR samples. This is attributed to the injection of highly spin polarised carriers that are believed to reduce the order parameter over the whole sample, and hence l sub C and the magnetic moment of the sample. As part of a search for colossal magneto-resistance (CMR) materials with Curie temperature below the superconducting transition of YBCO, we made an investigation of the magnetic and electrical characteristics of Chromium doped LCMO. We found that the conduction mechanism which depends on the orbital order via the double-exchange mechanism, is decoupled from the ferromagnetic behaviour, which is related to spin order. Work on the injection of dc-current from half metallic CMR material into YBa sub 2 Cu sub 3 O sub 7 sub - subdelta (YBCO) showed a shift and a compression in the ...

  7. Spin transfer torque in non-collinear magnetic tunnel junctions exhibiting quasiparticle bands: a non-equilibrium Green's function study

    Science.gov (United States)

    Jaya, Selvaraj Mathi

    2017-06-01

    A non-equilibrium Green's function formulation to study the spin transfer torque (STT) in non-collinear magnetic tunnel junctions (MTJs) exhibiting quasiparticle bands is developed. The formulation can be used to study the magnetoresistance and spin current too. The formulation is used to study the STT in model tunnel junctions exhibiting multiple layers and quasiparticle bands. The many body interaction that gives rise to quasiparticle bands is assumed to be a s - f exchange interaction at the electrode regions of the MTJ. The quasiparticle bands are obtained using a many body procedure and the single particle band structure is obtained using the tight binding model. The bias dependence of the STT as well as the influence of band occupancy and s - f exchange coupling strength on the STT are studied. We find from our studies that the band occupancy plays a significant role in deciding the STT and the s - f interaction strength too influences the STT significantly. Anomalous behavior in both the parallel and perpendicular components of the STT is obtained from our studies. Our results obtained for certain values of the band occupation are found to show the trend observed from the experimental measurements of STT.

  8. Silicon-based chalcogenide: Unexpected quantum spin Hall insulator with sizable band gap

    Science.gov (United States)

    Zhang, Run-wu; Zhang, Chang-wen; Ji, Wei-xiao; Li, Ping; Wang, Pei-ji; Li, Sheng-shi; Yan, Shi-shen

    2016-10-01

    Searching for two-dimensional (2D) silicon-based topological materials is imperative for the development of various innovative devices. Here, by using first-principles calculations, we discover the silicon-based chalcogenide Si2Te2 film to be a 2D quantum spin Hall (QSH) insulator with a fundamental band gap of 0.34 eV, which can be tunable under external strain. This nontrivial topological phase stems from band inversion between the Si-px,y and Te-px,y orbitals, demonstrated by a single pair of topologically protected helical edge states with Dirac point located in the bulk gap. Notably, the characteristic properties of edge states, such as the Fermi velocity and edge shape, can be engineered by edge modifications. Additionally, the BN sheet is an ideal substrate for the experimental realization of Si2Te2 films, without destroying its nontrivial topology. Our works open a meaningful route for designing topological spintronics devices based on 2D silicon-based films.

  9. BAND-STRUCTURE AND CLUSTER-MODEL CALCULATIONS OF LACOO(3) IN THE LOW-SPIN PHASE

    NARCIS (Netherlands)

    ABBATE, M; POTZE, R; SAWATZKY, GA; FUJIMORI, A

    1994-01-01

    We present band-structure and cluster-model calCulatiOns Of LaCoO3 in the low-spin phase. The purpose of these calculations is to contrast and complement the results and conclusions of recent spectroscopic studies. The total density of states (DOS) is compared to the photoemission spectrum; the agre

  10. Band renormalization and spin polarization of MoS{sub 2} in graphene/MoS{sub 2} heterostructures

    Energy Technology Data Exchange (ETDEWEB)

    Coy-Diaz, Horacio; Batzill, Matthias [Department of Physics, University of South Florida, Tampa, FL (United States); Bertran, Francois; Chen, Chaoyu; Avila, Jose; Rault, Julien; Le Fevre, Patrick; Asensio, Maria C. [Synchrotron SOLEIL, L' Orme des Merisiers, Gif sur Yvette (France)

    2015-12-15

    Transition metal dichalcogenides exhibit spin-orbit split bands at the K-point that become spin polarized for broken crystal inversion symmetry. This enables simultaneous manipulation of valley and spin degrees of freedom. While the inversion symmetry is broken for monolayers, we show here that spin polarization of the MoS{sub 2} surface may also be obtained by interfacing it with graphene, which induces a space charge region in the surface of MoS{sub 2}. Polarization induced symmetry breaking in the potential gradient of the space charge is considered to be responsible for the observed spin polarization. In addition to spin polarization we also observe a renormalization of the valence band maximum (VBM) upon interfacing of MoS{sub 2} with graphene. The energy difference between the VBM at the Γ-point and K-point shifts by ∝150 meV between the clean and graphene covered surface. (copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  11. A highly sensitive spin-valve transistor

    NARCIS (Netherlands)

    Erve, van 't O.M.J.; Vlutters, R.; Anil Kumar, P.S.; Kim, S.D.; Jansen, R.; Lodder, J.C.; Hadjipanayis, G.C.

    2001-01-01

    In this paper we present a spin-valve transistor made with a silicon on insulator wafer as emitter and a double sided polished Si wafer as collector. Using vacuum metal bonding we obtain a three terminal device in which a spin-valve layer is sandwiched between two Si wafers. We measure a 217% change

  12. Shape evolution at high spin states in Kr and Br isotopes

    Energy Technology Data Exchange (ETDEWEB)

    Trivedi, T. [Department of Pure and Physics, Guru Ghasidas Vishwavidyalaya, Bilaspur-495009 (India); Palit, R.; Naik, Z.; Jain, H. C. [Tata Institute of Fundamental Research, Mumbai-400005 (India); Negi, D.; Kumar, R.; Singh, R. P.; Muralithar, S.; Pancholi, S. C.; Bhowmik, R. K. [Inter University Accelerator Centre, New Delhi-110067 (India); Yang, Y.-C.; Sun, Y. [Department of Physics, Shanghai Jiao Tong University, Shanghai 200240 (China); Sheikh, J. A. [Department of Physics, University of Kashmir, Srinagar 190 006 (India); Raja, M. K. [Department of Nuclear Physics, Andhra University, Visakhapatnam-530003 (India); Kumar, S. [Department of Physics and Astrophysics, University of Delhi, Delhi-110007 (India); Choudhury, D. [Department of Physics, IIT Roorkee, Roorkee-247667 (India); Jain, A. K.; Mehrotra, I. [Department of Physics, University of Allahabad, Allahabad-211001 (India)

    2014-08-14

    The high spin states in A = 75, Kr and Br isotopes have been populated via fusion-evaporation reaction at an incident beam energy of 90 MeV. The de-exciting γ-rays were detected utilizing the Indian National Gamma Array (INGA). Lifetime of these excited high spin states were determined by Doppler-shift attenuation method. Experimental results obtained from lifetime measurement are interpreted in the frame work of projected shell-model to get better insight into the evolution of collectivity. Comparison of the calculations of the model with transitional quadrupole moments Q{sub t} of the positive and negative parity bands firmly established their configurations.

  13. High spin states in odd-odd {sup 132}Cs

    Energy Technology Data Exchange (ETDEWEB)

    Hayakawa, Takehito [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment; Lu, J.; Furuno, K. [and others

    1998-03-01

    Excited states with spin larger than 5 {Dirac_h} were newly established in the {sup 132}Cs nucleus via the {sup 124}Sn({sup 11}B,3n) reaction. Rotational bands built on the {nu}h{sub 11/2} x {pi}d{sub 5/2}, {nu}h{sub 11/2} x {pi}g{sub 7/2} and {nu}h{sub 11/2} x {pi}h{sub 11/2} configurations were observed up to spin I {approx} 16 {Dirac_h}. The {nu}h{sub 11/2} x {pi}h{sub 11/2} band shows inverted signature splitting below I < 14 {Dirac_h}. A dipole band was firstly observed in doubly odd Cs nuclei. (author)

  14. High-Tc spin superfluidity in antiferromagnets.

    Science.gov (United States)

    Bunkov, Yu M; Alakshin, E M; Gazizulin, R R; Klochkov, A V; Kuzmin, V V; L'vov, V S; Tagirov, M S

    2012-04-27

    We report the observation of the unusual behavior of induction decay signals in antiferromagnetic monocrystals with Suhl-Nakamura interactions. The signals show the formation of the Bose-Einstein condensation (BEC) of magnons and the existence of spin supercurrent, in complete analogy with the spin superfluidity in the superfluid (3)He and the atomic BEC of quantum gases. In the experiments described here, the temperature of the magnon BEC is a thousand times larger than in the superfluid (3)He. It opens a possibility to apply the spin supercurrent for various magnetic spintronics applications.

  15. Gate-controlled zero-magnetic-field spin splitting in the valence band of asymmetric AlGaAs/GaAs quantum wells

    Energy Technology Data Exchange (ETDEWEB)

    Hirmer, Michael; Hirmer, Marika; Schuh, Dieter; Wegscheider, Werner; Korn, Tobias; Schueller, Christian [Institut fuer Experimentelle und Angewandte Physik, Universitaet Regensburg (Germany)

    2010-07-01

    Zero-magnetic-field-spin-splitting (ZMFSS) in two-dimensional quantum wells (QW) induced by the structure inversion asymmetry, and its control, are of major importance for both fundamental research and spintronic applications, due to its influence on the dynamics and manipulation of the spin. In hole systems the asymmetry leads to a ZMFSS of the heavy hole (HH) states in third order of the in-plane wave vector k {sub parallel}. In our experiments, we focus on highly p-doped asymmetric 2D AlGaAs/GaAs quantum wells (QW). with different QW widths and spacer thicknesses and the manipulation of the Rashba spin splitting via top gates. We utilize electronic intersubband Raman measurements in backscattering geometry at 4.2 K. Using polarization selection rules, one can distinguish between charge-density excitation (CDE, polarized spectra) and spin-density excitation (SDE, depolarized spectra) in the Raman spectra. In all samples we observe a low-energy SDE with excitation energies in the range of 0-2 meV. Comparing these excitation energies to 8 band k.p calculations of the valence subbands, the SDE can be interpreted as an intersubband excitation of the spin-split HH ground state, reflecting directly the ZMFSS.

  16. High spin properties of 124Ba

    Indian Academy of Sciences (India)

    K Ilangovan; N Arunachalam

    2002-03-01

    The 124Ba nucleus is investigated on the basis of the method of statistical mechanics by assuming the nucleons to move in triaxially deformed Nilsson potential. The variation in the Fermi energies of protons and neutrons is studied as a function of spin and temperature. The Fermi energies determined as a function of angular momentum is used to study the dependence of shell correction on angular momentum using the Strutinsky smoothing procedure. The most important observation is that the shell correction is almost the same for all spins for 124Ba. The spin cutoff parameter and the single particle level density parameter are studied as a function of spin and temperature. Constant entropy lines drawn by plotting the excitation energy against angular momentum are found to be roughly at constant energy above the yrast line and are almost equally spaced. It is observed that no yrast traps are present for 124Ba.

  17. Lifetimes of High Spin States in an Odd-Proton Nucleus 129Cs

    Science.gov (United States)

    Wang, Lie-Lin; Zhu, Li-Hua; Lu, Jing-Bin; Wu, Xiao-Guang; Li, Guang-Sheng; Hao, Xin; Zheng, Yun; He, Chuang-Ye; Wang, Lei; Li, Xue-Qin; Liu, Ying; Pan, Bo; Zhao, Yan-Xin; Li, Zhong-Yu; Ding, Huai-Bo

    2010-02-01

    Lifetimes of high spin states in 129Cs are measured using the Doppler shift attenuation method. The high spin states of 129Cs are populated following the fusion evaporation reaction 124Sn(11B, 6n)129Cs at a beam energy of 65 MeV. The reduced transition probabilities B(E2) and the transition quadrupole moments Qt in the negative- and positive-parity bands are deduced. The experimental results indicate that the Qt values of the negative parity band are smaller than those of the positive parity bands, probably due to different γ-deformation driving effects of different proton orbitals. The Qt values exhibit a considerable increase near the band crossing region in these bands. This behavior demonstrates that nuclear shape changing results from the neutron or proton alignments. The signature splitting of the πh11/2 and πg7/2 bands shows the opposite changing trend after backbending due to the h11/2 neutron and h11/2 proton alignments, respectively.

  18. Shape evolution in 76,78Kr nuclei at high spins in tilted axis cranking Hartree–Fock–Bogoliubov approach

    Indian Academy of Sciences (India)

    A Ansari; P Sharma; U R Jakhar; H L Yadav

    2007-01-01

    A two-dimensional tilted axis cranking Hartree–Fock–Bogoliubov (CHFB) calculation is performed for 76Kr and 78Kr nuclei up to high spins = 30 employing a pairing-plus-quadrupole (PPQ) model interaction Hamiltonian. Intricate details of the evolution of single particle structures and shapes as a function of spin have been investigated. The results show the existence of energy levels with high quantum numbers lying close to the yrast line in both the nuclei. Such high states should exhibit isomeric characteristics due to the -selection rules for the -decays. Moreover, in 78Kr a new band with = 20–30 lying below the observed ground band is predicted.

  19. Polarization measurements and high-spin states in 8638Sr48

    Science.gov (United States)

    Kumar, Naveen; Kumar, Suresh; Kumar, V.; Mandal, S. K.; Palit, R.; Saha, S.; Sethi, J.; Trivedi, T.; Pancholi, S. C.; Srivastava, P. C.

    2016-11-01

    The high-spin states in 86Sr nucleus were populated using the 76Ge(13C, 3n) reaction at a beam energy of 45 MeV. The γ-γ and γ-γ-γ coincidence measurements were used to establish the level scheme up to 10.9 MeV excitation energy and spin Iπ =19+. In our preliminary results reported earlier, a positive-parity dipole (ΔI = 1) band based on the 6878-keV level having M1 γ-ray transitions was identified. In the present work, the γ-rays and their sequence have been established for this band. The band may have a magnetic rotational character. The spin-parity of the levels were assigned by measuring the Directional Correlations of the Oriented (DCO) nuclei and the polarization asymmetry. The polarization measurements were performed for the first time for the γ-ray transitions in this nucleus. The experimental band structures were compared with the shell-model calculations using two recent effective interactions, JUN45 and jj44b in the 1p3/2, 0f5/2, 1p1/2, 0g9/2 model space. From the Tilted-Axis Cranking (TAC) calculations, the 4-qp π(g9/2) 2 ⊗ ν(g9/2) - 2 configuration is suggested for the lower-part of the (ΔI = 1) band up to spin Iπ =16+ and the 6-qp π [(g9/2) 2(f5/2) 1(p1/2) 1 ] ⊗ ν(g9/2) - 2 configuration for the upper-part of the band.

  20. High-spin states in the vibrational nucleus {sup 114}Cd

    Energy Technology Data Exchange (ETDEWEB)

    Jungclaus, A. [Universidad Autonoma de Madrid, E-28049, Madrid (Spain); Instituto de Estructura de la Materia, Consejo Superior de Investigaciones Cientificas, E-28006, Madrid (Spain); Algora, A. [IFIC-Universidad de Valencia, E-46071, Valencia (Spain); Axiotis, M.; Gadea, A.; Martinez, T.; Napoli, D.R. [INFN, Laboratori Nazionali di Legnaro, I-35020, Legnaro (Italy); Borge, M.J.G.; Piqueras, I. [Instituto de Estructura de la Materia, Consejo Superior de Investigaciones Cientificas, E-28006, Madrid (Spain); Fernandez, M.A. [Universidad Autonoma de Madrid, E-28049, Madrid (Spain); Galindo, E.; Hausmann, M. [II. Physikalisches Institut, Universitaet Goettingen, D-37073, Goettingen (Germany); Lenzi, S.; Ur, C. [Dipartimento di Fisica dell' Universita and INFN, Sezione di Padova, I-35131, Padova (Italy); Schwengner, R. [Institut fuer Kern- und Hadronenphysik, Forschungszentrum Rossendorf, D-01314, Dresden (Germany)

    2004-04-01

    High-spin states of the neutron-rich vibrational nucleus {sup 114}Cd have been studied using the incomplete fusion reaction {sup 110}Pd({sup 7}Li,p2n) and the GASP spectrometer in conjunction with the ISIS Si ball. About 50 new states with excitation energies up to 7 MeV and angular momentum I {<=}(18 +) were observed and for many of them, spin and parity could be firmly assigned. The band-like structures in {sup 114}Cd are compared to the corresponding ones in the even-even neighbour {sup 112}Cd. (orig.)

  1. Description of multi-quasiparticle bands by the tilted axis cranking model 21.60.-n; High K rotational bands; Tilted axis cranking; Multi-quasiparticle configurations

    CERN Document Server

    Frauendorf, S

    2000-01-01

    The selfconsistent cranking approach is extended to the case of rotation about an axis which is tilted with respect to the principal axes of the deformed potential (Tilted Axis Cranking). Expressions for the energies and the intra bands electro-magnetic transition probabilities are given. The mean field solutions are interpreted in terms of quantal rotational states. The construction of the quasiparticle configurations and the elimination of spurious states is discussed. The application of the theory to high spin data is demonstrated by analyzing the multi-quasiparticle bands in the nuclides with N=102,103 and Z=71,72,73.

  2. High Spin Isomers and Super Heavy Elements (SHE) Synthesis

    Science.gov (United States)

    Popescu, Domitian G.

    2010-04-01

    To get closer to the SHE-Island the new radioactive beams are proposed for future fusion reaction. We suggest something different : to use the advantage of High Spin Isomer States, by tacking into account the importance of the G (spin-isospin cupling) suggested by Ripka 1.

  3. High Spins Beyond Rarita-Schwinger Framework

    CERN Document Server

    Kirchbach, M; Kirchbach, Mariana; Napsuciale, Mauro

    2004-01-01

    We explicitly construct in the Rarita-Schwinger representation space the operator of the squared Pauli-Lubanski vector and derive from it that the -15/4 m^{2} subspace (spin 3/2 in the rest frame), with well defined parity, is pinned down by the one sole equation, [\\epsilon_{\\alpha\\beta\\mu\\sigma}\\gamma_{5}\\gamma^{\\mu}p^{\\sigma} -m g_{\\alpha\\beta}]\\psi^{\\beta}=0. We argue that upon gauging the new equation leads to causal spin-3/2 propagation within an electromagnetic field, thus resolving the Velo-Zwanziger problem.

  4. Investigation of the high spin structure of Zr88

    Science.gov (United States)

    Saha, S.; Palit, R.; Sethi, J.; Biswas, S.; Singh, P.; Trivedi, T.; Choudhury, D.; Srivastava, P. C.

    2014-04-01

    High spin states of Zr88 were populated with Se80(C13, 5n) fusion evaporation reaction. A thin target as well as Au backed target were used in two different experiments for the present study. Excited levels of Zr88 have been observed up to spin ˜20ℏ and an excitation energy of ˜10 MeV. Spin and parity of most of the states have been determined from directional correlation and polarization measurements. The level scheme was substantially extended with the addition of a number of high spin states and transitions. The comparison of the measured levels of Zr88 with large shell model calculations based on the full unrestricted f5/2pg9/2 model space established the dominance of shell-model excitation up to the highest observed spin.

  5. High-spin organic molecules with dominant spin-orbit contribution and unprecedentedly large magnetic anisotropy

    Science.gov (United States)

    Misochko, Eugenii Ya.; Akimov, Alexander V.; Masitov, Artem A.; Korchagin, Denis V.; Yakushchenko, Igor K.; Chapyshev, Sergei V.

    2012-08-01

    High-spin organic molecules with dominant spin-orbit contribution to magnetic anisotropy are reported. Quintet 4-azido-3,5-dibromopyridyl-2,6-dinitrene (Q-1), quintet 2-azido-3,5-dibromopyridyl-4,6-dinitrene (Q-2), and septet 3,5-dibromopyridyl-2,4,6-trinitrene (S-1) were generated in solid argon matrices by ultraviolet irradiation of 2,4,6-triazido-3,5-dibromopyridine. The zero-field splitting (ZFS) parameters, derived from electron spin resonance spectra, show unprecedentedly large magnitudes of the parameters D: |DQ1| = 0.289, |DQ2| = 0.373, and |DS1| = 0.297 cm-1. The experimental ZFS parameters were successfully reproduced by density functional theory calculations, confirming that magnetic anisotropy of high-spin organic molecules can considerably be enhanced by the "heavy atom effect." In bromine-containing high-spin nitrenes, the spin-orbit term is dominant and governs both the magnitude and the sign of magnetic anisotropy. The largest negative value of D among septet trinitrenes is predicted for 1,3,5-trinitrenobenzene bearing three heavy atoms (Br) in positions 2, 4, and 6 of the benzene ring.

  6. Orbital mapping of energy bands and the truncated spin polarization in three-dimensional Rashba semiconductors

    CERN Document Server

    Liu, Qihang; Dessau, D S; Zunger, Alex

    2016-01-01

    Associated with spin-orbit coupling (SOC) and inversion symmetry breaking, Rashba spin polarization opens a new avenue for spintronic applications that was previously limited to ordinary magnets. However, spin polarization effects in actual Rashba systems are far more complicated than what conventional single-orbital models would suggest. By studying via first-principles DFT and a multi-orbital k.p model a 3D bulk Rashba system (free of complications by surface effects) we find that the physical origin of the leading spin polarization effects is SOC-induced hybridization between spin and multiple orbitals, especially those with nonzero orbital angular momenta. In this framework we establish a general understanding of the orbital mapping, common to the surface of topological insulators and Rashba system. Consequently, the intrinsic mechanism of various spin polarization effects, which pertain to all Rashba systems even those with global inversion symmetry, is understood as a manifestation of the orbital textur...

  7. Quasi 2D electronic states with high spin-polarization in centrosymmetric MoS2 bulk crystals

    Science.gov (United States)

    Gehlmann, Mathias; Aguilera, Irene; Bihlmayer, Gustav; Młyńczak, Ewa; Eschbach, Markus; Döring, Sven; Gospodarič, Pika; Cramm, Stefan; Kardynał, Beata; Plucinski, Lukasz; Blügel, Stefan; Schneider, Claus M.

    2016-06-01

    Time reversal dictates that nonmagnetic, centrosymmetric crystals cannot be spin-polarized as a whole. However, it has been recently shown that the electronic structure in these crystals can in fact show regions of high spin-polarization, as long as it is probed locally in real and in reciprocal space. In this article we present the first observation of this type of compensated polarization in MoS2 bulk crystals. Using spin- and angle-resolved photoemission spectroscopy (ARPES), we directly observed a spin-polarization of more than 65% for distinct valleys in the electronic band structure. By additionally evaluating the probing depth of our method, we find that these valence band states at the point in the Brillouin zone are close to fully polarized for the individual atomic trilayers of MoS2, which is confirmed by our density functional theory calculations. Furthermore, we show that this spin-layer locking leads to the observation of highly spin-polarized bands in ARPES since these states are almost completely confined within two dimensions. Our findings prove that these highly desired properties of MoS2 can be accessed without thinning it down to the monolayer limit.

  8. Quasi 2D electronic states with high spin-polarization in centrosymmetric MoS2 bulk crystals.

    Science.gov (United States)

    Gehlmann, Mathias; Aguilera, Irene; Bihlmayer, Gustav; Młyńczak, Ewa; Eschbach, Markus; Döring, Sven; Gospodarič, Pika; Cramm, Stefan; Kardynał, Beata; Plucinski, Lukasz; Blügel, Stefan; Schneider, Claus M

    2016-06-01

    Time reversal dictates that nonmagnetic, centrosymmetric crystals cannot be spin-polarized as a whole. However, it has been recently shown that the electronic structure in these crystals can in fact show regions of high spin-polarization, as long as it is probed locally in real and in reciprocal space. In this article we present the first observation of this type of compensated polarization in MoS2 bulk crystals. Using spin- and angle-resolved photoemission spectroscopy (ARPES), we directly observed a spin-polarization of more than 65% for distinct valleys in the electronic band structure. By additionally evaluating the probing depth of our method, we find that these valence band states at the point in the Brillouin zone are close to fully polarized for the individual atomic trilayers of MoS2, which is confirmed by our density functional theory calculations. Furthermore, we show that this spin-layer locking leads to the observation of highly spin-polarized bands in ARPES since these states are almost completely confined within two dimensions. Our findings prove that these highly desired properties of MoS2 can be accessed without thinning it down to the monolayer limit.

  9. High-speed spinning of ultra-high molecular weight polyethylene fibres

    NARCIS (Netherlands)

    Roukema, Mees

    1991-01-01

    This thesis deals with the spinning of ultra-high molecular weight polyethylene ( UHMWPE ) fibres at high speeds, and the effects of the spinning parameters on the fibre properties. Polyethylene fibres with strengths up to 7.2 GPa can be produced in a gel-spinning and hot-drawing procedure. In this

  10. High-speed spinning of ultra-high molecular weight polyethylene fibres

    NARCIS (Netherlands)

    Roukema, Mees

    1991-01-01

    This thesis deals with the spinning of ultra-high molecular weight polyethylene ( UHMWPE ) fibres at high speeds, and the effects of the spinning parameters on the fibre properties. Polyethylene fibres with strengths up to 7.2 GPa can be produced in a gel-spinning and hot-drawing procedure. In this

  11. High-spin states in the odd-odd nucleus sup 8 sup 0 Y

    CERN Document Server

    Bucurescu, D; Ionescu-Bujor, M; Iordachescu, A; Bazzacco, D; Brandolini, F; De Angelis, G; De Poli, M; Gadea, A; Lunardi, S; Marginean, N; Medina, N H; Napoli, D R; Pavan, P; Rossi-Alvarez, C; Spolaore, P

    2002-01-01

    The high-spin states of sup 8 sup 0 Y have been studied with the reactions sup 2 sup 4 Mg( sup 5 sup 8 Ni, pn gamma) at 180 MeV and sup 5 sup 8 Ni( sup 2 sup 4 Mg, pn gamma) at 77 MeV. Gamma-ray transitions in this nucleus have been unambiguously assigned by using the GASP detector array in conjunction with the recoil mass spectrometer CAMEL and the ISIS Silicon detector ball. These transitions have been arranged into several rotational bands extending up to an excitation energy of about 12 MeV and spin 24 Planck constant. The bands are discussed within the framework of the interacting boson-fermion-fermion and cranked shell models.

  12. High-spin states in the odd-odd nucleus {sup 80}Y

    Energy Technology Data Exchange (ETDEWEB)

    Bucurescu, D. E-mail: bucurescu@tandem.nipne.ro; Ur, C.A.; Ionescu-Bujor, M.; Iordachescu, A.; Bazzacco, D.; Brandolini, F.; De Angelis, G.; De Poli, M.; Gadea, A.; Lunardi, S.; Marginean, N.; Medina, N.H.; Napoli, D.R.; Pavan, P.; Rossi Alvarez, C.; Spolaore, P

    2002-07-01

    The high-spin states of {sup 80}Y have been studied with the reactions {sup 24}Mg({sup 58}Ni, pn{gamma}) at 180 MeV and {sup 58}Ni({sup 24}Mg, pn{gamma}) at 77 MeV. Gamma-ray transitions in this nucleus have been unambiguously assigned by using the GASP detector array in conjunction with the recoil mass spectrometer CAMEL and the ISIS Silicon detector ball. These transitions have been arranged into several rotational bands extending up to an excitation energy of about 12 MeV and spin 24 {Dirac_h}. The bands are discussed within the framework of the interacting boson-fermion-fermion and cranked shell models.

  13. High Precision Fiber SINS with Spin Technology

    Institute of Scientific and Technical Information of China (English)

    孙伟; 孙枫; 王大雪

    2013-01-01

    Fiber strapdown inertial navigation system (FSINS) is presently used in several applications related to marine navigation. However, the absolute position from FSINS contains the error that increases with time, which prevents its long-term use for the ship cruise. In order to improve the performance of FSINS based on our present inertial sensors, the spin technology was proposed in the system to mitigate the navigation errors and a prototype of the proposed system was developed in Navigation Lab. The prototype contains the IMU, temperature controller, rotating configuration, navigation and I/O electronics group, control and display, power supply subsystem and other modules. In the proposed spin technology, the IMU is rotated back and forth in azimuth through four orthogonal positions relative to the ship’s longitudinal axis. Experimental testing was conducted for the prototype in the laboratory and the results showed that the RFSINS’s navigation performance is improved 10 times.

  14. First Results on High-spin States in ^179Au

    Science.gov (United States)

    Mueller, W. F.; Bingham, C. R.; Reviol, W.; Riedinger, L. L.; Smith, B. H.; Wauters, J.; Ahmad, I.; Amro, H. A.; Blumenthal, D. J.; Carpenter, M. P.; Davids, C. N.; Fischer, S. M.; Hackman, G.; Henderson, D. J.; Janssens, R. V. F.; Khoo, T. L.; Lauritsen, T.; Lister, C. J.; Nisius, D. T.; Seweryniak, D.; Ma, W. C.

    1996-05-01

    High-spin states in ^179Au were studied for the first time in two experiments at the Argonne uc(atlas) facility. The ^144Sm(^40Ar,p4n)^179Au reaction at 207 MeV was used for the first experiment and ^124Te(^58Ni,p2n)^179Au at 255 MeV in the second. The setup in the first experiment consisted of the Fragment Mass Analyzer (uc(fma)) plus Parallel Plate Avalanche Counter (uc(ppac)) system and 10 Compton-suppressed Ge detectors (CSG's). From this run, several transitions from the yrast bands were established. The latter experiment utilized the uc(fma) + uc(ppac) system in conjunction with the uc(aye-ball) array of 19 Ge detectors (eight >70% efficient CSG's, nine 25% efficient CSG's, and two LEPS; one with Compton suppression) and a double sided silicon strip detector (uc(dssd).) The results from these experiments, including a level scheme, will be presented and discussed.

  15. First example of a high-level correlated calculation of the indirect spin-spin coupling constants involving tellurium

    DEFF Research Database (Denmark)

    Rusakov, Yury Yu; Krivdin, Leonid B.; Østerstrøm, Freja From;

    2013-01-01

    This paper documents a very first example of a high-level correlated calculation of spin-spin coupling constants involving tellurium taking into account relativistic effects, vibrational corrections and solvent effects for the medium sized organotellurium molecules. The 125Te-1H spin-spin coupling...... of spin-spin coupling constants involving tellurium, was developed. The SOPPA methods show much better performance as compared to 15 those of DFT, if relativistic effects calculated within the ZORA scheme are taken into account. Vibrational and solvent corrections are next to negligible, while...

  16. Angular dependence of dipole-dipole-Curie-spin cross-correlation effects in high-spin and low-spin paramagnetic myoglobin.

    Science.gov (United States)

    Pintacuda, Guido; Hohenthanner, Karin; Otting, Gottfried; Müller, Norbert

    2003-10-01

    The (15)N-HSQC spectra of low-spin cyano-met-myoglobin and high-spin fluoro-met-myoglobin were assigned and dipole-dipole-Curie-spin cross-correlated relaxation rates measured. These cross-correlation rates originating from the dipolar (1)H-(15)N interaction and the dipolar interaction between the (1)H and the Curie spin of the paramagnetic center contain long-range angular information about the orientation of the (1)H-(15)N bond with respect to the iron-(1)H vector, with information measurable up to 11 A from the metal for the low-spin complex, and between 10 to 25 A for the high-spin complex. Comparison of the experimental data with predictions from crystal structure data showed that the anisotropy of the magnetic susceptibility tensor in low spin cyano-met-myoglobin significantly influences the cross-correlated dipole-dipole-Curie-spin relaxation rates.

  17. HIGH-SPIN STATES IN CE-131

    NARCIS (Netherlands)

    PALACZ, M; SUJKOWSKI, Z; NYBERG, J; BACELAR, J; JONGMAN, J; HESSELINK, W; NASSER, J; PLOMPEN, A; WYSS, R

    1991-01-01

    Gamma ray spectra from the Sn-117(O-18, 4n)131Ce reaction have been studied with the NORDBALL array of 15 Compton-suppressed Ge detectors. States up to I = 51/2 h, E almost-equal-to 8 MeV are populated. Observed bands are interpreted in terms of quasiparticle configurations.

  18. High-spin structure of neutron-rich Dy isotopes

    Indian Academy of Sciences (India)

    A Ansari; H L Yadav; M Kaushik; U R Jakhar

    2003-06-01

    In view of recent experimental progress on production and spectroscopy of neutron-rich isotopes of Dy with mass number = 166 and 168, we have made theoretical investigations on the structure of high spin states of 164-170Dy isotopes in the cranked Hartree–Fock–Bogoliubov (CHFB) theory employing a pairing+quadrupole+hexadecapole model interaction. With the increase of neutron number the rotation alignment of the proton orbitals dominates the structure at high spins, which is clearly reflected in the spin dependence of the rotational g-factors. A particularly striking feature is the difference in the spin-dependent properties of 166Dy as compared to that of 164Dy.

  19. High-spin states in the {sup 97}Tc nucleus

    Energy Technology Data Exchange (ETDEWEB)

    Bucurescu, D.; Cata-Danil, G.; Cata-Danil, I.; Ivascu, M.; Marginean, N.; Rusu, C.; Stroe, L.; Ur, C.A. [National Institute of Physics and Nuclear Engineering, P.O. Box MG-6, Bucharest 76900 (Romania); Gadea, A. [INFN, Laboratori Nazionali di Legnaro, Legnaro (Italy)

    2003-04-01

    High-spin states in the {sup 97}Tc nucleus have been studied by in-beam {gamma}-ray spectroscopy with the reaction {sup 82}Se({sup 19}F,4n{gamma}) at 68 MeV incident energy. Excited states have been observed up to about 8 MeV excitation and spin 43/2{Dirac_h}. The observed level scheme is compared with results of shell model calculations. (orig.)

  20. High-spin states in the {sup 96}Tc nucleus

    Energy Technology Data Exchange (ETDEWEB)

    Bucurescu, D.; Cata-Danil, G.; Cata-Danil, I.; Ivascu, M.; Marginean, N.; Rusu, C.; Stroe, L.; Ur, C.A. [National Inst. of Physics and Nuclear Engineering, Bucharest (Romania); Gizon, A.; Gizon, J. [Inst. des Sciences Nucleaires, IN2P3-CNRS/UPJ, Grenoble (France); Nyako, B.; Timar, J.; Zolnai, L. [Inst. of Nuclear Research, Debrecen (Hungary); Boston, A.J.; Joss, D.T.; Paul, E.S.; Semple, A.T. [Oliver Lodge Lab., Liverpool Univ. (United Kingdom); Parry, C.M. [Dept. of Physics, York Univ., Heslington, York (United Kingdom)

    2001-03-01

    High-spin states in the {sup 96}Tc nucleus have been studied with the reactions {sup 82}Se({sup 19}F,5n{gamma}) at 68 MeV and Zn({sup 36}S,{alpha}pxn) at 130 MeV. Two {gamma}-ray cascades (irregular bandlike structures) have been observed up to an excitation energy of about 10 MeV and spin 21-22{Dirac_h}. (orig.)

  1. K-band high power latching switch

    Science.gov (United States)

    Mlinar, M. J.; Piotrowski, W. S.; Raue, J. E.

    1980-12-01

    A 19 GHz waveguide latching switch with a bandwidth of 1400 MHz and an exceptionally low insertion loss of 0.25 dB was demonstrated. The RF and driver ferrites are separate structures and can be optimized individually. This analysis for each structure is separately detailed. Basically, the RF section features a dual turnstile junction. The circulator consists of a dielectric tube which contains two ferrite rods, and a dielectric spacer separating the ferrite parts along the center of symmetry of the waveguide to form two turnstiles. This subassembly is indexed and locked in the center of symmetry of a uniform junction of three waveguides by the metallic transformers installed in the top and bottom walls of the housing. The switching junction and its actuating circuitry met all RF performance objectives and all shock and vibration requirements with no physical damage or performance degradation. It exceeds thermal requirements by operating over a 100 C temperature range (-44 C to +56 C) and has a high power handling capability allowing up to 100 W of CW input power.

  2. High-Spin Structure in Neutron-Rich 108Ru Nucleus

    Institute of Scientific and Technical Information of China (English)

    CHE Xing-Lai; J. O. Rasmussen; Y. X. Luo; W. C. Ma; ZHU Sheng-Jiang; J.H Hamilton; A.V.Ramayya; J.K.Hwang; U Yong-Nam; LI Ming-Liang; ZHENG Rang-Chen; I.Y.Lee

    2004-01-01

    High spin states in the neutron-rich 108Ru nucleus have been studied through measuring prompt γγ-ray coincidences following the spontaneous fission of 252Cf with the Gammasphere detector array. The yrast band has been confirmed. The one-phonon γ-vibrational band and the two-quasiparticle band based on the 5- level have been extended up to 13+ and 15-, respectively. In addition, two levels at 1644.8kev and 1826.5kev excitation energies are newly identified and proposed to be the members of a two-phonon γ-vibrational band. It is shown that the 108Ru nucleus has triaxial deformation with parametersβ2 ~ 0.29 and γγ = -22° from the total Routhian surface calculations. The observed band crossing in the yrast band is due to the alignment of a pair of h11/2 neutrons according to the cranked shell model calculations. The possible configuration for the two-quasiparticle band has been discussed.

  3. Band splitting and relative spin alignment in two-layer systems

    CERN Document Server

    Ovchinnikov, A A

    2002-01-01

    It is shown that the single-particle spectra of the low Hubbard zone in the two-layer correlated 2D-systems sharply differ in the case of different relative alignment of the layers spin systems. The behavior of the two-layer splitting in the Bi sub 2 Sr sub 2 CaCu sub 2 O sub 8 sub + subdelta gives all reasons for the hypothesis on the possible rearrangement of the F sub z -> AF sub z alignment configuration, occurring simultaneously with the superconducting transition. The effects of the spin alignment on the magnetic excitations spectrum, as the way for studying the spin structure of the two-layer systems, are discussed by the example of homogenous solutions for the effective spin models

  4. High-spin states and lifetime measurements in sup 1 sup 7 sup 1 Hf

    CERN Document Server

    Cullen, D M; Appelbe, D E; Wilson, A N; Paul, E S; Bergström, M H; Sharpey-Schafer, J F; Baktash, C; Frosch, I; Lee, I Y; Macchiavelli, A O; MacLeod, R W; Prevost, D; Theisen, C; Curien, D

    2000-01-01

    This paper describes the results of two complementary experiments which studied the properties of the well-deformed nucleus sup 1 sup 7 sup 1 Hf. The first experiment, with a thin self-supporting target, extended the rotational bands built upon the [633]7/2, [512]5/2 and [521]1/2 configurations up to spins of 73/2-85/2 Planck constant. The configurations of these bands and observed band crossings are discussed within the framework of the cranked-shell model. The second experiment employed a backed target in order to measure the lifetimes, by the Doppler Shift Attenuation method, and thereby establish deformations for some of the states in the collective rotational bands. The extracted deformations are found to be consistent with those predicted from theoretical Total Routhian Surface calculations. These deformations provide strong evidence that the high-spin states in sup 1 sup 7 sup 1 Hf, and perhaps more importantly, in the region where the high-K (K suppi=19/2 sup + and K suppi=23/2 sup -) isomeric states ...

  5. Investigation of optical band gap and device parameters of rubrene thin film prepared using spin coating technique

    Energy Technology Data Exchange (ETDEWEB)

    Tuğluoğlu, Nihat, E-mail: tugluo@gmail.com [Department of Technology, Sarayköy Nuclear Research and Training Center, 06983 Saray, Ankara (Turkey); Barış, Behzad; Gürel, Hatice [Department of Physics, Faculty of Arts and Sciences, Giresun University, Gazipaşa Campus, Giresun 28100 (Turkey); Karadeniz, Serdar [Department of Technology, Sarayköy Nuclear Research and Training Center, 06983 Saray, Ankara (Turkey); Yüksel, Ömer Faruk [Department of Physics, Faculty of Science, Selçuk University, Campus Konya 42075 (Turkey)

    2014-01-05

    Highlights: • Thin film of rubrene has been deposited by spin coating technique. • The band gap properties of the film were investigated in the range 200–700 nm. • The analysis of the absorption coefficient revealed indirect allowed transition. • The parameters such as barrier height and ideality factor were determined. -- Abstract: Rubrene thin film has been deposited by spin coating technique. The optical band gap properties of rubrene thin film have been investigated in the spectral range 200–700 nm. The results of the absorption coefficient (α) were analyzed in order to determine the optical band gap and Urbach energy of the film. The absorption spectra recorded in the UV–vis region shows two peaks at 250 nm and 300 nm. The analysis of the spectral behavior of the absorption coefficient (α) in the absorption region revealed indirect allowed transition with corresponding energy 2.31 eV. The value of Urbach energy (E{sub U}) was determined to be 1.169 eV. The current–voltage (I–V) characteristics and electrical conduction properties of rubrene/n-Si device fabricated by spin coating method have also been investigated. The I–V characteristic in dark was showed the rectification effect due to the formation of Schottky barrier at rubrene/silicon interface. From analyzing the I-V measurement for the device, the basic device parameters such as barrier height, ideality factor and series resistance were determined. At the low-voltage region, the current conduction in Au/rubrene/n-Si device is ohmic type. The charge transport phenomenon appears to be space charge limited current (SCLC) at higher-voltage regions.

  6. Identical high- K three-quasiparticle rotational bands

    Science.gov (United States)

    Kaur, Harjeet; Singh, Pardeep

    2016-12-01

    A comprehensive study of high- K three-quasiparticle rotational bands in odd- A nuclei indicates the similarity in γ -ray energies and dynamic moment of inertia Im^{(2)} . The extent of the identicality between the rotational bands is evaluated by using the energy factor method. For nuclei pairs exhibiting identical bands, the average relative change in the dynamic moment of inertia Im^{(2)} is also determined. The identical behaviour shown by these bands is attributed to the interplay of nuclear structure parameters: deformation and the pairing correlations. Also, experimental trend of the I(hbar) vs. hbar ω (MeV) plot for these nuclei pairs is shown to be in agreement with Tilted-Axis Cranking (TAC) model calculations.

  7. Ka-band MMIC microstrip array for high rate communications

    Science.gov (United States)

    Lee, R. Q.; Raquet, C. A.; Tolleson, J. B.; Sanzgiri, S. M.

    1991-01-01

    In a recent technology assessment of alternative communication systems for the space exploration initiative (SEI), Ka-band (18 to 40 GHz) communication technology was identified to meet the mission requirements of telecommunication, navigation, and information management. Compared to the lower frequency bands, Ka-band antennas offer higher gain and broader bandwidths; thus, they are more suitable for high data rate communications. Over the years, NASA has played an important role in monolithic microwave integrated circuit (MMIC) phased array technology development, and currently, has an ongoing contract with Texas Instrument (TI) to develop a modular Ka-band MMIC microstrip subarray (NAS3-25718). The TI contract emphasizes MMIC integration technology development and stipulates using existing MMIC devices to minimize the array development cost. The objective of this paper is to present array component technologies and integration techniques used to construct the subarray modules.

  8. A dual band high impedance antenna for RF Harvest applications

    Science.gov (United States)

    Medina, Andres J.

    A design for a compact dual band very high impedance antenna for RF Harvest applications is presented. The antenna is designed to present a very high input impedance at its feed point at 900 MHz and 1.8 GHz. The design incorporates the folding concept into a customized bowtie antenna to achieve high input impedance. The design methodology and simulations are presented, as well as a comparison of the measured results against the simulation results. A rectifier circuit and dual band matching network are also simulated and presented.

  9. Particle-number conserving analysis of the high-spin structure of $^{159}$Ho

    CERN Document Server

    Zhang, Zhen-Hua

    2016-01-01

    The high-spin rotational bands in odd-$Z$ nuclei $^{159}$Ho ($Z=67$) are investigated using the cranked shell model with the pairing correlations treated by a particle-number conserving method, in which the blocking effects are taken into account exactly. The experimental moments of inertia and alignments and their variations with the rotational frequency $\\hbar\\omega$ are reproduced very well by the calculations. The splitting between the signature partners of the yrast band $7/2^-[523]$ is discussed and the splitting of the excited band $7/2^+[404]$ above $\\hbar\\omega \\sim 0.30$~MeV is predicted due to the level crossing with $1/2^+[411]$. The calculated $B(E2)$ transition probabilities are also suggested for future experiments.

  10. Highly Efficient L-Band Fibre -DFB Lasers

    Institute of Scientific and Technical Information of China (English)

    Libin Fu; Morten Ibsen; David J. Richardson; David N. Payne

    2003-01-01

    A more than 12 mW highly efficient fibre-DFB laser operating at 1618.3 nm is fabricated and characterised. Its high-power, low-noise and single-polarisation characteristics make it very suitable WDM-source for L-band transmission.

  11. Simulation study of the high intensity S-Band photoinjector

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Xiongwei; Nakajima, Kazuhisa [High Energy Accelerator Research Organization, Tsukuba, Ibaraki (Japan)

    2001-10-01

    In this paper, we report the results of simulation study of the high intensity S-Band photoinjector. The aim of the simulation study is to transport high bunch charge with low emittance evolution. The simulation result shows that 7nC bunch with rms emittance 22.3 {pi} mm mrad can be outputted at the exit of photoinjector. (author)

  12. Spin-resolved photoelectron spectroscopy using femtosecond extreme ultraviolet light pulses from high-order harmonic generation

    Science.gov (United States)

    Plötzing, M.; Adam, R.; Weier, C.; Plucinski, L.; Eich, S.; Emmerich, S.; Rollinger, M.; Aeschlimann, M.; Mathias, S.; Schneider, C. M.

    2016-04-01

    The fundamental mechanism responsible for optically induced magnetization dynamics in ferromagnetic thin films has been under intense debate since almost two decades. Currently, numerous competing theoretical models are in strong need for a decisive experimental confirmation such as monitoring the triggered changes in the spin-dependent band structure on ultrashort time scales. Our approach explores the possibility of observing femtosecond band structure dynamics by giving access to extended parts of the Brillouin zone in a simultaneously time-, energy- and spin-resolved photoemission experiment. For this purpose, our setup uses a state-of-the-art, highly efficient spin detector and ultrashort, extreme ultraviolet light pulses created by laser-based high-order harmonic generation. In this paper, we present the setup and first spin-resolved spectra obtained with our experiment within an acquisition time short enough to allow pump-probe studies. Further, we characterize the influence of the excitation with femtosecond extreme ultraviolet pulses by comparing the results with data acquired using a continuous wave light source with similar photon energy. In addition, changes in the spectra induced by vacuum space-charge effects due to both the extreme ultraviolet probe- and near-infrared pump-pulses are studied by analyzing the resulting spectral distortions. The combination of energy resolution and electron count rate achieved in our setup confirms its suitability for spin-resolved studies of the band structure on ultrashort time scales.

  13. Spin orbit splitting in the valence bands of ZrS{sub x}Se{sub 2−x}: Angle resolved photoemission and density functional theory

    Energy Technology Data Exchange (ETDEWEB)

    Moustafa, Mohamed, E-mail: moustafa@physik.hu-berlin.de [Institut für Physik, Humboldt Universität zu Berlin, Newtonstr. 15, D-12489 Berlin (Germany); Faculty of Engineering, Pharos University in Alexandria, Canal El Mahmoudia Str., Alexandria (Egypt); Ghafari, Aliakbar; Paulheim, Alexander; Janowitz, Christoph; Manzke, Recardo [Institut für Physik, Humboldt Universität zu Berlin, Newtonstr. 15, D-12489 Berlin (Germany)

    2013-08-15

    Highlights: ► We performed high resolution ARPES on 1T–ZrS{sub x}Se{sub 2−x}. ► A characteristic splitting of the chalcogen p-derived VB along high symmetry directions was observed. ► The splitting size at the A point of the BZ is found to increase from 0.06 to 0.31 eV from ZrS{sub 2} towards ZrSe{sub 2}. ► Electronic structure calculations based on the DFT were performed using the model of TB–MBJ. ► The calculations show that the splitting is due to SO coupling of the valence bands. -- Abstract: Angle-resolved photoelectron spectroscopy using synchrotron radiation has been performed on 1T–ZrS{sub x}Se{sub 2−x}, where x varies from 0 to 2, in order to study the influence of the spin-orbit interaction in the valence bands. The crystals were grown by chemical vapour transport technique using Iodine as transport agent. A characteristic splitting of the chalcogen p-derived valence bands along high symmetry directions has been observed experimentally. The size of the splitting increases with the increase of the atomic number of the chalcogenide, e.g. at the A point of the Brillouin zone from 0.06 eV to 0.31 eV with an almost linear dependence with x, as progressing from ZrS{sub 2} towards ZrSe{sub 2}, respectively. Electronic structure calculations based on the density functional theory have been performed using the model of Tran–Blaha [1] and the modified version of the exchange potential proposed by Becke and Johnson [2] (TB–MBJ) both with and without spin-orbit (SO) coupling. The calculations show that the splitting is mainly due to spin-orbit coupling and the degeneracy of the valance bands is lifted.

  14. Renormalization of spin polarized itinerant electron bands in the normal state of a model ferromagnetic superconductor

    Institute of Scientific and Technical Information of China (English)

    Ma Lei; Huang Ai-Qun; Li Jun

    2011-01-01

    This paper studies the normal state properties of itinerant electrons in a toy model, which is constructed according to the model for coexisting ferromagnetism and superconductivity proposed by Suhl [Suhl H 2001 Phys. Rev. Lett. 87 167007]. In this theory with ferromagnetic ordering based on localized spins, the exchange interaction J between conduction electrons and localized spin is taken as the pairing glue for s-wave superconductivity. It shows that this J term will first renormalize the normal state single conduction electron structures substantially. It finds dramatically enhanced or suppressed magnetization of itinerant electrons for positive or negative J. Singlet Cooper pairing can be ruled out due to strong spin polarisation in the J > 0 case while a narrow window for s-wave superconductivity is opened around some ferromagnetic J.

  15. Formation and Stability of High-Spin Alkali Clusters

    Science.gov (United States)

    Schulz, C. P.; Claas, P.; Schumacher, D.; Stienkemeier, F.

    2004-01-01

    Helium nanodroplet isolation has been applied to agglomerate alkali clusters at temperatures of 380mK. The very weak binding to the surface of the droplets allows a selection of only weakly bound, high-spin states. Here we show that larger clusters of alkali atoms in high-spin states can be formed. The lack of strong bonds from pairing electrons makes these systems nonmetallic, vanderWaals like complexes of metal atoms. We find that sodium and potassium readily form such clusters containing up to 25atoms. In contrast, this process is suppressed for rubidium and cesium. Apparently, for these heavy alkalis, larger high-spin aggregates are not stable and depolarize spontaneously upon cluster formation.

  16. HIGH-ACCURACY BAND TO BAND REGISTRATION METHOD FOR MULTI-SPECTRAL IMAGES OF HJ-1A/B

    Institute of Scientific and Technical Information of China (English)

    Lu Hao; Liu Tuanjie; Zhao Haiqing

    2012-01-01

    Band-to-band registration accuracy is an important parameter of multispectral data.A novel band-to-band registration approach with high precision is proposed for the multi-spectral images of HJ-1A/B.Firstly,the main causes resulted in misregistration are analyzed,and a high-order polynomial model is proposed.Secondly,a phase fringe filtering technique is employed to Phase Correlation Method based on Singular Value Decomposition (SVD-PCM) for reducing the noise in phase difference matrix.Then,experiments are carried out to build nonlinear registration models,and images of green band and red band are aligned to blue band with an accuracy of 0.1 pixels,while near infrared band with an accuracy of 0.2 pixels.

  17. XVI Workshop on High Energy Spin Physics (D-SPIN2015)

    Science.gov (United States)

    Lednicky, Richard

    2016-02-01

    Dear Colleagues, Ladies and Gentlemen, on behalf of the Directorate of Joint Institute for Nuclear Research (JINR) it is a pleasure for me to welcome you here to Dubna for the 16th International Workshop on High Energy Spin Physics. It provides an opportunity to present and discuss the news accumulated during last year. Another important feature of this series of workshops has always been the participation of a large number of physicists from the former Soviet Union and Eastern European countries, for which long trips have previously been limited by financial (and earlier also by bureaucratic) reasons. It thus represents an important addition to the series of large International Symposia on spin physics held in even-numbered years in different countries, including the Symposium held in Dubna in 2012. JINR has a long-lasting tradition of experimental and theoretical studies of spin phenomena. The workshops on high energy spin physics started in Dubna in 1981 due to the initiative of L. Lapidus, an outstanding theoretical physicist. Since then, these meetings have been held in Dubna in every odd year and have become regular thanks to Anatoly Vasilievich Efremov, the chairman for many years. Recent years have brought a lot of new experimental results, and above all the discovery and determination of quantum characteristics of the Higgs boson at the Large Hadron Collider.

  18. Spin dynamics in highly frustrated pyrochlore magnets

    Science.gov (United States)

    Petit, Sylvain; Guitteny, Solène; Robert, Julien; Bonville, Pierre; Decorse, Claudia; Ollivier, Jacques; Mutka, Hannu; Mirebeau, Isabelle

    2015-01-01

    This paper aims at showing the complementarity between time-of-flight and triple-axis neutron scattering experiments, on the basis of two topical examples in the field of geometrical magnetic frustration. Rare earth pyrochlore magnets R2Ti2O7 (R is a rare earth) play a prominent role in this field, as they form model systems showing a rich variety of ground states, depending on the balance between dipolar, exchange interactions and crystal field. We first review the case of the XY antiferromagnet Er2 Ti2 O7. Here a transition towards a Néel state is observed, possibly induced by an order-by-disorder mechanism. Effective exchange parameters can be extracted from S(Q,ω). We then examine the case of the spin liquid Tb2 Ti2 O7. Recent experiments reveal a complex ground state characterized by "pinch points" and supporting a low energy excitation. These studies demonstrate the existence of a coupling between crystal field transitions and a transverse acoustic phonon mode.

  19. Electron Spin Pairing in High-Tc Superconductors

    Institute of Scientific and Technical Information of China (English)

    郭卫; 韩汝珊

    2001-01-01

    An electron pairing theory based on effective electron spin coupling mediated by antiferromagnetically correlated local moments is presented to account for high-Tc phenomena. We show that Kondo scattering and the suppression of the antiferromagnetic superexchange between Cu2+ moments lead to local triplet pairing, the mechanism underlying high-Tc superconductivity.

  20. High-Spin States and Level Structure in Stable Nucleus 84Sr

    CERN Document Server

    Shen, Shuifa; Han, Guangbing; Wen, Shuxian; Yan, Yupeng; Yan, Shiwei; Wu, Xiaoguang; Zhu, Lihua; Li, Guangsheng; He, Chuangye

    2011-01-01

    High-spin states of 84Sr were populated through the reaction 70Zn(18O, 4n)84Sr at 75 MeV beam energy. Measurement of excitation function, gamma-gamma coincidences, directional correlation of oriented states (DCO) ratios and gamma-transition intensities were performed using eight anticompton HPGe detectors and one planar HPGe detector. Based on the measured results, a new level scheme of 84Sr was established in which 12 new states and nearly 30 new gamma-transitions were identified in the present work. The positive-parity states of the new level scheme were compared with results from calculations in the framework of the projected shell model (PSM). One negative-parity band was extended to spin I=19 and it can be found that in the high-spin states the gamma-transition energies show the nature of signature staggering. The negative-parity band levels are in good agreement with the deformed configuration-mixing shell model (DCM) calculations.

  1. Necking Point in PET High-speed Fiber Spinning

    Institute of Scientific and Technical Information of China (English)

    王夏琴; 唐志廉

    2001-01-01

    Cross-over method is established to predict necking point for PET high- speed fiber spinning. Even slowly crystallizing polymers such as PET can crystallize on the spinline at sufficiently high spinning speed. The development of rtmning velocity, temperature, crystallinity and theological force is investigated for the take-up velocity over a range of 6 000 - 10 000 m/min. The position of necking point, temperature rise and abrupt increase of crystallinity move closer to the spinneret with the increase of take-up velocity,

  2. Effect of interfaces and the spin-orbit band on the band gaps of InAs/GaSb superlattices beyond the standard envelope-function approximation

    Science.gov (United States)

    Szmulowicz, F.; Haugan, H.; Brown, G. J.

    2004-04-01

    We develop a modified 8×8 envelope-function approximation (EFA) formalism for the noncommon-atom (NCA) superlattices (SL’s), incorporating the effect of anisotropic and other interface (IF) interactions that go beyond the standard EFA. The boundary conditions in the presence of IF interactions are used to set up a secular equation (including a transfer matrix derivation) whose physical transparency makes possible a number of valuable insights (possibility of IF bound states, analytic solutions, indirect gaps, etc.). We show that the heavy-hole spin-orbit IF coupling is very important due to the IF localization of the SO wave function components and the ability of the IF potential to potentially bind a hole at the IF’s, all of which pose convergence problems for perturbative solutions. With two adjustable parameter for the two possible IF’s, we find a very good agreement between experiment and theory for the band gaps of several sets of very long-infrared and midinfrared InAs/GaSb SL’s grown at several laboratories and by us. The band gaps as a function of GaSb and InAs widths are explained in terms of variations of the HH and conduction (C) band bandwidths. We show that the cut-off wavelengths can be reduced by increasing the GaSb layer width. Thus, a consistent application of the EFA method with the inclusion of well established IF effects can provide useful physical insights and possesses good predictive capacity in the design of NCA SL’s.

  3. Highly retrievable spin-wave-photon entanglement source.

    Science.gov (United States)

    Yang, Sheng-Jun; Wang, Xu-Jie; Li, Jun; Rui, Jun; Bao, Xiao-Hui; Pan, Jian-Wei

    2015-05-29

    Entanglement between a single photon and a quantum memory forms the building blocks for a quantum repeater and quantum network. Previous entanglement sources are typically with low retrieval efficiency, which limits future larger-scale applications. Here, we report a source of highly retrievable spin-wave-photon entanglement. Polarization entanglement is created through interaction of a single photon with an ensemble of atoms inside a low-finesse ring cavity. The cavity is engineered to be resonant for dual spin-wave modes, which thus enables efficient retrieval of the spin-wave qubit. An intrinsic retrieval efficiency up to 76(4)% has been observed. Such a highly retrievable atom-photon entanglement source will be very useful in future larger-scale quantum repeater and quantum network applications.

  4. Exploring THz band for high speed wireless communications

    DEFF Research Database (Denmark)

    Yu, Xianbin; Zhang, Hangkai; Jia, Shi;

    2016-01-01

    We overview recent trend in developing high speed wireless communication systems by exploring large bandwidth available in the THz band, and we also present our recent experimental achievements on 400 GHz wireless transmission with a data rate of up to 60 Gbit/s by using a uni-travelling carrier...

  5. Dual Band High Efficiency Power Amplifier Based on CRLH Lines

    Directory of Open Access Journals (Sweden)

    D. Segovia-Vargas

    2009-12-01

    Full Text Available In this paper we propose the use of Composite Right/Left Hand (CRLH and Extended Composite Right/Left Hand (ECRLH transmission lines for the design of dual band high efficiency power amplifiers working in CE class. The harmonic termination can be synthesized using the meta-lines is particularly suitable for CE class amplifiers, which have a termination not as sensitive to the third harmonic as F class amplifier. This paper presents the design procedure and the design equations. The nonlinear phase response of a CRLH and ECRLH transmission line has been utilized to design arbitrary dual-band amplifiers.

  6. Determination of the molecular structure of the short-lived light-induced high-spin state in the spin-crossover compound [Fe(6-mepy)3tren](PF6)2

    Science.gov (United States)

    Chakraborty, Pradip; Tissot, Antoine; Peterhans, Lisa; Guénée, Laure; Besnard, Céline; Pattison, Philip; Hauser, Andreas

    2013-06-01

    In the spin-crossover compound [Fe(6-mepy)3tren](PF6)2, (6-mepy)3tren = tris{4-[(6-methyl)-2-pyridyl]-3-aza-butenyl}amine, the high-spin state can be populated as a metastable state below the thermal transition temperature via irradiation into the metal to the ligand charge-transfer absorption band of the low-spin species. At 10 K, the lifetime of this metastable state is only 1 s. Despite this, it is possible to determine an accurate excited state structure by following the evolution of relevant structural parameters by synchrotron x-ray diffraction under continuous irradiation with increasing intensity. The difference in metal-ligand bond length between the high-spin and the low-spin states is found to be 0.192 Å, obtained from an analysis of the experimental data using the mean-field approximation to model cooperative effects.

  7. Datta-and-Das spin transistor controlled by a high-frequency electromagnetic field

    Science.gov (United States)

    Sheremet, A. S.; Kibis, O. V.; Kavokin, A. V.; Shelykh, I. A.

    2016-04-01

    We developed the theory of spin dependent transport through a spin-modulator device (so-called Datta-and-Das spin transistor) in the presence of a high-frequency electromagnetic field (dressing field). Solving the Schrödinger problem for dressed electrons, we demonstrated that the field drastically modifies the spin transport. In particular, the dressing field leads to renormalization of spin-orbit coupling constants that varies conductivity of the spin transistor. The present effect paves the way for controlling the spin-polarized electron transport with light in prospective spin-optronic devices.

  8. Spins in the vortices of a high-temperature superconductor

    DEFF Research Database (Denmark)

    Lake, B.; Aeppli, G.; Clausen, K.N.

    2001-01-01

    Neutron scattering is used to characterize the magnetism of the vortices for the optimally doped high-temperature superconductor La2-xSrxCuO4 (x = 0.163) in an applied magnetic field. As temperature is reduced, Low-frequency spin fluctuations first disappear with the loss of vortex mobility......, but then reappear. We find that the vortex state can be regarded as an inhomogeneous mixture of a superconducting spin fluid and a material containing a nearly ordered antiferromagnet. These experiments show that as for many other properties of cuprate superconductors, the important underlying microscopic forces...

  9. Gross shell structure at high spin in heavy nuclei

    CERN Document Server

    Deleplanque, M A; Pashkevich, V V; Chu, S Y; Unzhakova, A

    2004-01-01

    Experimental nuclear moments of inertia at high spins along the yrast line have been determined systematically and found to differ from the rigid-body values. The difference is attributed to shell effects and these have been calculated microscopically. The data and quantal calculations are interpreted by means of the semiclassical Periodic Orbit Theory. From this new perspective, features in the moments of inertia as a function of neutron number and spin, as well as their relation to the shell energies can be understood. Gross shell effects persist up to the highest angular momenta observed.

  10. Gross shell structure at high spin in heavy nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Deleplanque, Marie-Agnes; Frauendorf, Stefan; Pashkevich, Vitaly V.; Chu, S.Y.; Unzhakova, Anja

    2003-10-07

    Experimental nuclear moments of inertia at high spins along the yrast line have been determined systematically and found to differ from the rigid-body values. The difference is attributed to shell effect and these have been calculated microscopically. The data and quantal calculations are interpreted by means of the semiclassical Periodic Orbit Theory. From this new perspective, features in the moments of inertia as a function of neutron number and spin, as well as their relation to the shell energies can be understood. Gross shell effects persist up to the highest angular momenta observed.

  11. Nuclear Level Density at High Spin and Excitation Energy

    Institute of Scientific and Technical Information of China (English)

    A.N. Behkami; Z. Kargar

    2001-01-01

    The intensive studies of equilibrium processes in heavy-ion reaction have produced a need for information on nuclear level densities at high energies and spins. The Fermi gas level density is often used in investigation of heavy-ion reaction studies. Some papers have claimed that nuclear level densities might deviate substantially from the Fermi gas predications at excitations related to heavy-ion reactions. The formulae of calculation of the nuclear level density based on the theory of superconductivity are presented, special attention is paid to the dependence of the level density on the angular momentum. The spin-dependent nuclear level density is evaluated using the pairing interaction. The resulting level density for an average spin of 52h is evaluated for 155Er and compared with experimental data. Excellent agreement between experiment and theory is obtained.``

  12. High-spin molecular resonances in 12C + 12C

    Science.gov (United States)

    Uegaki, E.; Abe, Y.

    2016-05-01

    Resonances observed in the 12C + 12C collisions are studied with a molecular model. At high spins J = 10-18, a stable dinuclear configuration is found to be an equator-equator touching one. Firstly, normal modes have been solved around the equilibrium, with spin J and K-quantum number being specified for rotation of the whole system. Secondly, with respect to large centrifugal energy, Coriolis coupling has been diagonalized among low-lying 11 states of normal-mode excitations, which brings K-mixing. The analyses of decay widths and excitation functions have been done. The molecular ground state exhibits alignments of the orbital angular momentum and the 12C spins, while some of the molecular excited states exhibit disalignments with small widths. Those results are surprisingly in good agreement with the experiments, which will light up a new physical picture of the highspin 12C + 12C resonances.

  13. Nuclear structure of 216Ra at high spin

    Indian Academy of Sciences (India)

    S Muralithar; G Rodrigues; R P Singh; R K Bhowmik; P Mukherjee; B Sethi; I Mukherjee

    2012-09-01

    High-spin states of 216Ra ( = 88, = 128) have been investigated through 209Bi(10B, 3n) reaction at an incident beam energy of 55 MeV and 209Bi(11B, 4n) reaction at incident beam energies ranging from 65 to 78 MeV. Based on coincidence data, the level scheme for 216Ra has been considerably extended up to $∼ 33\\hbar$ spin and 7.2 MeV excitation energy in the present experiment with placement of 28 new -transitions over what has been reported earlier. Tentative spin-parity assignments are done for the newly proposed levels on the basis of the DCO ratios corresponding to strong gates. Empirical shell model calculations were carried out to provide an understanding of the underlying nuclear structure.

  14. High spin polarization and spin splitting in equiatomic quaternary CoFeCrAl Heusler alloy

    Energy Technology Data Exchange (ETDEWEB)

    Bainsla, Lakhan; Mallick, A.I. [Department of Physics, Indian Institute of Technology Bombay, Mumbai 400076 (India); Coelho, A.A. [Instituto de Física “Gleb Wataghin”, Universidade Estadual de Campinas-UNICAMP, SP 6165, Campinas 13 083-859, Sao Paulo (Brazil); Nigam, A.K. [DCMPMS, Tata Institute of Fundamental Research, Mumbai 4000052 (India); Varaprasad, B.S.D.Ch.S.; Takahashi, Y.K. [Magnetic Materials Unit, National Institute for Materials Science, Tsukuba 305-0047 (Japan); Alam, Aftab [Department of Physics, Indian Institute of Technology Bombay, Mumbai 400076 (India); Suresh, K.G., E-mail: suresh@phy.iitb.ac.in [Department of Physics, Indian Institute of Technology Bombay, Mumbai 400076 (India); Hono, K. [Magnetic Materials Unit, National Institute for Materials Science, Tsukuba 305-0047 (Japan)

    2015-11-15

    In this paper, we investigate CoFeCrAl alloy by means of ab-initio electronic structure calculations and various experimental techniques. The alloy is found to exist in the B2-type cubic Heusler structure, which is very similar to Y-type (or LiMgPdSn prototype) structure with space group F-43m (#216). Saturation magnetization (M{sub S}) of about 2 µ{sub B}/f.u. is observed at 8 K under ambient pressure, which is in good agreement with the Slater–Pauling rule. M{sub S} values are found to be independent of pressure, which is a prerequisite for half-metals. The ab-initio electronic structure calculations predict half-metallicity for the alloy with a spin slitting energy of 0.31 eV. Importantly, this system shows a high current spin polarization value of 0.67±0.02, as deduced from the point contact Andreev reflection measurements. Linear dependence of electrical resistivity with temperature indicates the possibility of reasonably high spin polarization at elevated temperatures (~150 K) as well. All these suggest that CoFeCrAl is a promising material for the spintronic devices. - Highlights: • The ab-initio calculations predict half-metallic nature for the alloy. • Saturation magnetization (M{sub S}) gives characteristics of half-metallic nature. • Current spin polarization (P) value of 0.67±0.02 is deduced from PCAR measurements. • Deduced P is higher than those obtained for many ternary and/or quaternary alloys. • Resistivity behavior gives signature of high P at elevated temperatures.

  15. High Temperature Spectrum for v3 Band of Carbon Dioxide

    Institute of Scientific and Technical Information of China (English)

    SONG Xiao-Shu; YANG Xiang-Dong; UO Yun-Dong; WANG Jun; CHENG Xin-Lu; LING-HU Rong Feng

    2007-01-01

    The total internal partition sums (TIPS) are calculated at the temperature up to 6000 K for 12C16O2. Using the calculated partition functions, we produce the line intensities of v3 band of 12C16O2 at several high temperatures.The results show that the calculated line intensities are in very good agreement with those of HITRAN database at the temperature up to 3000 K, which provides a strong support for the calculations of TIPS and line intensities at high temperature. Then the calculation is extended to further high temperature, and the simulated spectra of v3 band of 12C16O2 at 5000 and 6000 K are reported.

  16. Solution-state dynamics of sugar-connected spin probes in sucrose solution as studied by multiband (L-, X-, and W-band) electron paramagnetic resonance.

    Science.gov (United States)

    Fukui, Kôichi; Ito, Tomohiro; Tada, Mika; Aoyama, Masaaki; Sato, Shingo; Onodera, Jun ichi; Ohya, Hiroaki

    2003-07-01

    A multiband (L-band, 0.7GHz; X-band, 9.4GHz; and W-band, 94GHz) electron paramagnetic resonance (EPR) study was performed for two glycosidated spin probes, 4-(alpha,beta-D-glucopyranosyloxy)-TEMPO (Glc-TEMPO) and 4-(alpha,beta-D-lactopyranosyloxy)-TEMPO (Lac-TEMPO), and one non-glycosylated spin probe, 4-hydroxy-TEMPO (TEMPOL), where TEMPO=2,2,6,6-tetramethyl-1-piperidinyloxyl, to characterize fundamental hydrodynamic properties of sugar-connected spin probes. The linewidths of these spin probes were investigated in various concentrations of sucrose solutions (0-50wt%). The multiband approach has allowed full characterization of the linewidth parameters, providing insights into the molecular shapes of the spin probes in sucrose solution. The analysis based on the fast-motional linewidth theory has yielded anisotropy parameters of rho(x) approximately 2.6 and rho(y) approximately 0.9 for Glc-TEMPO, and rho(x) approximately 4.2 and rho(y) approximately 0.9 for Lac-TEMPO. These values indicate that the glycosidated spin probes have a prolate-type molecular shape elongated along the x-axis (NO(rad) axis) with Lac-TEMPO elongated more remarkably, consistent with their molecular structures. The interaction parameters k (the ratios of the effective hydrodynamic volumes to the real ones) corrected for the difference in molecular shape have been estimated and found to have the relation k(TEMPOL)spin probes can have stronger hydrogen bonding to water. Glycosidated spin probes are expected to be useful for probing sugar-involving interactions, which commonly occur in biological systems. Thus this study will provide an indispensable basis for such spin-probe studies.

  17. Spin dynamics of electron with high excess energy in GaAs investigated by the simplified circularly dichromatic pump-probe model

    Science.gov (United States)

    Teng, L. H.; Mu, L. J.; Wang, X.

    2014-03-01

    Time-resolved circularly polarized pump-probe spectroscopy is used to study the spin dynamics of electron with high excess energy in bulk GaAs at room temperature, an abnormal phenomenon that the curve taken from co-helicity circularly polarized pump-probe beam drops below the curve taken from cross-helicity circularly polarized pump-probe beam is observed. With both the spin-dependent band-filling and band-gap renormalization effects being taken into account, a simplified circularly dichromatic pump-probe model is further developed, the model can be used to fit the scanning experimental traces to retrieve the spin relaxation time, carrier recombination time, intensity coefficient of spin-dependent band-filling and band-gap renormalization effects, etc. With the parameters retrieved from the experimental data, the physical origin of the spectrum reversal can be explained in detail, both of the spin-dependent band-filling and band-gap renormalization effects contribute to the reversal spectrum.

  18. Inter-spin distance determination using L-band (1-2 GHz) non-adiabatic rapid sweep electron paramagnetic resonance (NARS EPR)

    Science.gov (United States)

    Kittell, Aaron W.; Hustedt, Eric J.; Hyde, James S.

    2012-08-01

    Site-directed spin-labeling electron paramagnetic resonance (SDSL EPR) provides insight into the local structure and motion of a spin probe strategically attached to a molecule. When a second spin is introduced to the system, macromolecular information can be obtained through measurement of inter-spin distances either by continuous wave (CW) or pulsed electron double resonance (ELDOR) techniques. If both methodologies are considered, inter-spin distances of 8-80 Å can be experimentally determined. However, there exists a region at the upper limit of the conventional X-band (9.5 GHz) CW technique and the lower limit of the four-pulse double electron-electron resonance (DEER) experiment where neither method is particularly reliable. The work presented here utilizes L-band (1.9 GHz) in combination with non-adiabatic rapid sweep (NARS) EPR to address this opportunity by increasing the upper limit of the CW technique. Because L-band linewidths are three to seven times narrower than those at X-band, dipolar broadenings that are small relative to the X-band inhomogeneous linewidth become observable, but the signal loss, due to the frequency dependence of the Boltzmann factor, has made L-band especially challenging. NARS has been shown to increase sensitivity by a factor of five, and overcomes much of this loss, making L-band distance determination more feasible [1]. Two different systems are presented, and distances of 18-30 Å have been experimentally determined at physiologically relevant temperatures. Measurements are in excellent agreement with a helical model and values determined by DEER.

  19. Observing bulk diamond spin coherence in high-purity nanodiamonds

    Science.gov (United States)

    Knowles, Helena S.; Kara, Dhiren M.; Atatüre, Mete

    2014-01-01

    Nitrogen-vacancy (NV) centres in diamond are attractive for research straddling quantum information science, nanoscale magnetometry and thermometry. Whereas ultrapure bulk diamond NVs sustain the longest spin coherence times among optically accessible spins, nanodiamond NVs exhibit persistently poor spin coherence. Here we introduce high-purity nanodiamonds accommodating record-long NV coherence times, >60 μs, observed through universal dynamical decoupling. We show that the main contribution to decoherence comes from nearby nitrogen impurities rather than surface states. We protect the NV spin free precession, essential to d.c. magnetometry, by driving solely these impurities into the motional narrowing regime. This extends the NV free induction decay time from 440 ns, longer than that in type Ib bulk diamond, to 1.27 μs, which is comparable to that in type IIa (impurity-free) diamond. These properties allow the simultaneous exploitation of both high sensitivity and nanometre resolution in diamond-based emergent quantum technologies.

  20. Dry spinning approach to continuous graphene fibers with high toughness.

    Science.gov (United States)

    Tian, Qishi; Xu, Zhen; Liu, Yingjun; Fang, Bo; Peng, Li; Xi, Jiabin; Li, Zheng; Gao, Chao

    2017-08-31

    Graphene fiber (GF) has emerged as a new carbonaceous fiber species since graphene-based liquid crystals were discovered. The growing performances of GFs in terms of their mechanical performance and their functionalities have assured their extensive applications in structural materials and functional textiles. To date, many spinning strategies utilizing coagulation baths have been applied in GF, which necessitates a complicated washing process. Dry spinning is a more convenient and green method for use with fibers in the chemical fiber industry, and should be a good option for GFs; however, this technique has never been used in a system of GF. In this research, first the dry spinning technique was used to fabricate continuous GFs and the dry spun GFs showed good toughness and flexibility. The dry spinnability of graphene oxide liquid crystals was achieved by choosing dispersive solvents with low surface tension and high volatility. The dry spun neat GFs possessed high toughness up to 19.12 MJ m(-3), outperforming the wet spun neat GFs. This dry spinning methodology facilitates the green fabrication of fibers of graphene and graphene-beyond two-dimensional nanomaterials, and it may also be extended to other printing technologies for complex graphene architectures.

  1. Inelastic neutron scattering study of spin excitations in the superconducting state of high temperature superconductors; Etude par diffusion inelastique de neutrons des excitations de spin dans la phase supraconductrice des supraconducteurs a haute temperature

    Energy Technology Data Exchange (ETDEWEB)

    Sidis, Y.; Pailhes, St.; Fauque, B.; Bourges, Ph. [CEA Saclay, Lab. Leon Brillouin, CNRS, 91 - Gif-sur-Yvette (France); Hinkov, V.; Ulrich, C.; Keimer, B. [Max-Planck-Institut fur Fertkorperforschung, Stuttgart (Germany); Capogna, L.; Ivanov, A. [Institut Laue-Langevin, 38 - Grenoble (France); Regnault, L.P. [CEA Grenoble, Dept. de Recherche Fondamentale sur la Matiere Condensee, 38 (France)

    2007-09-15

    Inelastic neutron scattering is a powerful technique that can measure magnetic correlations in a large momentum and energy range. In strongly correlated electronic systems, where spin, orbital, lattice and charge degrees of freedom are entangled, it is currently used to study the magnetic properties and shed light on their role in the appearance of the exotic electronic properties, such as unconventional superconductivity. In this article, we focus on the observation by inelastic neutron scattering technique of unconventional spin triplet collective modes in the superconducting state of high temperature superconducting cuprates and its interplay with anomalies in the charge excitation spectrum. The triplet spin mode is interpreted as a spin exciton, within a spin band model. Alternative scenarios based on localized or dual (itinerant localized) models are also mentioned. (authors)

  2. Banks of templates for all-sky narrow-band searches of gravitational waves from spinning neutron stars

    CERN Document Server

    Pisarski, Andrzej

    2013-01-01

    We construct efficient banks of templates suitable for all-sky narrow-band searches of almost monochromatic gravitational waves originating from spinning neutron stars in our Galaxy in data collected by interferometric detectors. We thus assume that both the position of the gravitational-wave source in the sky and the wave's frequency together with spindown parameters are unknown. In the construction we employ simplified model of the signal with constant amplitude and phase which is a linear function of unknown parameters. All our template banks enable usage of the fast Fourier transform algorithm in the computation of the maximum-likelihood $\\mathcal{F}$-statistic for nodes of the grids defining the bank and fulfill an additional constraint needed to resample the data to barycentric time efficiently. Our template banks are suitable for larger range of search parameters than the banks previously proposed and compared to them they have smaller thicknesses for certain values of search parameters.

  3. Island of high-spin isomers near N = 82

    Energy Technology Data Exchange (ETDEWEB)

    Pedersen, J.; Back, B.B.; Bernthal, F.M.; Bjornholm, S.; Borggreen, J.; Christensen, O.; Folkmann, F.; Herskind, B.; Khoo, T.L.; Neiman, M.; Puehlhofer, F.; Sletten, G.

    1977-10-17

    Experiments aimed at testing for the existence of yrast traps are reported. A search for delayed ..gamma.. radiation of lifetimes longer than approx. 10 ns and of high multiplicity has been performed by producing more than 100 compound nuclei between Ba and Pb in bombardments with /sup 40/Ar, /sup 50/Ti, and /sup 65/Cu projectiles. An island of high-spin isomers is found to exist in the region 64 < or approx. = Z > or approx. = 71 and N < or approx. = 82.

  4. High temperature resistant nanofiber by bubbfil-spinning

    Directory of Open Access Journals (Sweden)

    Li Ya

    2015-01-01

    Full Text Available Heat-resisting nanofibers have many potential applications in various industries, and the bubbfil spinning is the best candidate for mass-production of such materials. Polyether sulfone/zirconia solution with a bi-solvent system is used in the experiment. Experimental result reveals that polyether sulfone/zirconia nanofibers have higher resistance to high temperature than pure polyether sulfone fibers, and can be used as high-temperature-resistant filtration materials.

  5. Spin polarization in high density quark matter

    DEFF Research Database (Denmark)

    Bohr, Henrik; Panda, Prafulla K.; Providênci, Constanca

    2013-01-01

    We investigate the occurrence of a ferromagnetic phase transition in high density hadronic matter (e.g., in the interior of a neutron star). This could be induced by a four-fermion interaction analogous to the one which is responsible for chiral symmetry breaking in the Nambu-Jona-Lasinio model......, to which it is related through a Fierz transformation. Flavor SU(2) and flavor SU(3) quark matter are considered. A second-order phase transition is predicted at densities about 5 times the normal nuclear matter density. It is also found that in flavor SU(3) quark matter, a first-order transition from...

  6. On Spin Hamiltonian fits to Moessbauer spectra of high-spin Fe(II) porphyrinate systems

    Energy Technology Data Exchange (ETDEWEB)

    Schulz, Charles E., E-mail: cschulz@knox.edu [Knox College, Department of Physics (United States); Hu Chuanjiang, E-mail: scheidt.1@nd.edu; Scheidt, W. Robert [University of Notre Dame, Department of Chemistry and Biochemistry (United States)

    2006-06-15

    Fits to Moessbauer spectra of high-spin iron(II) porphyrinates have been applied to the Fe(II) model compounds octaethylporphyrin(1,2-dimethylimidazole) and tetra-paramethoxyporphyrin(1,2-dimethylimidazole). Moessbauer spectra have been measured on these compounds at 4.2 K in large applied fields. Spin Hamiltonians were used for fitting both the electronic and nuclear interactions. The fits are done by adjusting the Hamiltonian parameters to simultaneously minimize the total {chi}{sup 2} for three different applied fields. In order to get best fits, the EFG tensor need to be rotated relative to the ZFS tensor. A comparative sensitivity analysis of their Spin Hamiltonian parameters has also been done on the ZFS parameters D, and the EFG asymmetry parameter {eta}. The best fits suggest that both systems definitely have a negative quadrupole splitting, and that largest EFG component is tilted far from the z-axis of the ZFS tensor, which is likely to be near the heme normal.

  7. Kondo effect and spin quenching in high-spin molecules on metal substrates

    Science.gov (United States)

    Jacob, D.; Soriano, M.; Palacios, J. J.

    2013-10-01

    Using a state-of-the art combination of density functional theory and impurity solver techniques, we present a complete and parameter-free picture of the Kondo effect in the high-spin (S=3/2) coordination complex known as manganese phthalocyanine adsorbed on the Pb(111) surface. We calculate the correlated electronic structure and corresponding tunnel spectrum and find an asymmetric Kondo resonance, as recently observed in experiments. Contrary to previous claims, the Kondo resonance stems from only one of three possible Kondo channels with origin in the Mn 3d orbitals, its peculiar asymmetric shape arising from the modulation of the hybridization due to a strong coupling to the organic ligand. The spectral signature of the second Kondo channel is strongly suppressed as the screening occurs via the formation of a many-body singlet with the organic part of the molecule. Finally, a spin-1/2 in the 3d shell remains completely unscreened due to the lack of hybridization of the corresponding orbital with the substrate, hence leading to a spin-3/2 underscreened Kondo effect.

  8. Development of X-band accelerating structures for high gradients

    Institute of Scientific and Technical Information of China (English)

    S. Bini; M. G. Grimaldi; L. Romano; F. Ruffino; R. Parodi; V. Chimenti; A. Marcelli; L. Palumbo; B. Spataro; V. A. Dolgashev; S. Tantawi; A.D. Yeremian; Y. Higashi

    2012-01-01

    Short copper standing wave (SW) structures operating at an X-band frequency have been recently designed and manufactured at the Laboratori Nazionali di Frascati of the Istituto Nazionale di Fisica Nucleare (INFN) using the vacuum brazing technique.High power tests of the structures have been performed at the SLAC National Accelerator Laboratory.In this manuscript we report the results of these tests and the activity in progress to enhance the high gradient performance of the next generation of structures,particularly the technological characterization of high performance coatings obtained via molybdenum sputtering.

  9. Design of High Power Density Amplifiers: Application to Ka Band

    Science.gov (United States)

    Passi, Davide; Leggieri, Alberto; Di Paolo, Franco; Bartocci, Marco; Tafuto, Antonio

    2017-06-01

    Recent developments in the design of high-power-high-frequency amplifiers are assessed in this paper by the analysis and measurements of a high power density amplifier operating in the Ka Band. Design procedure is presented and a technical investigation is reported. The proposed device has shown over 23% of useful frequency bandwidth. It is an ensemble of 16 monolithic solid state power amplifiers that employees mixed technologies as spatial and planar combiners. Test performed have given maximum delivered power of 47.2 dBm.

  10. Lifetimes of High Spin Yrast States in Odd-Proton Nucleus 131Pr

    Institute of Scientific and Technical Information of China (English)

    李广生; 孟锐; 竺礼华; 张振龙; 王月; 王治民; 温书贤; 陆景彬; 赵广义; 李险峰; 文立军; 郑永南; 郑勇; 刘运祚; 袁观俊; 杨春祥

    2003-01-01

    Lifetimes of the high spin yrast states in the odd-proton-nucleus 131Pr have been determined by analysing the Doppler broadened line shapes for the de-exciting γ-rays following the 116Sn(19F, 4n) 131Pr reaction at a bombarding energy of 95 MeV. The transition quadrupole moments extracted from the measured lifetimes exhibit a considerable reduction near the rotational frequency of 0.42 MeV, at which the J(1) and J(2) moments of inertia indicate a band crossing. The experimental result demonstrates occurrence of the nuclear shape change induced by band crossing associated with the alignment of a pair of h11/2 protons.

  11. Spectroscopic quadrupole moments of high-spin isomers in {sup 193}Pb

    Energy Technology Data Exchange (ETDEWEB)

    Balabanski, D.L. [IKS, University of Leuven, Celestijnenlaan 200 D, B-3001, Leuven (Belgium); Faculty of Physics, St. Kliment Ohridski University of Sofia, BG-1164, Sofia (Bulgaria); Ionescu-Bujor, M.; Iordachescu, A.; Bucurescu, D. [National Institute for Physics and Nuclear Engineering, P.O. Box MG-6, Bucharest (Romania); Bazzacco, D.; Brandolini, F.; Menegazzo, R.; Pavan, P.; Rossi Alvarez, C. [Dipartimento di Fisica dell' Universita di Padova and INFN, Sezione di Padova, Padova (Italy); Chmel, S.; Huebel, H. [ISKP, Universitaet Bonn, D-53115, Bonn (Germany); Danchev, M. [Faculty of Physics, St. Kliment Ohridski University of Sofia, BG-1164, Sofia (Bulgaria); De Poli, M. [Laboratori Nazionali di Legnaro, INFN, Legnaro (Italy); Georgiev, G. [Grand Accelerateur National d' Ions Lourds, F-14076, Caen Cedex 5 (France); Haas, H. [Bereich Festkorperphysik, Hahn-Meitner Institut, D-14109, Berlin (Germany); Marginean, N. [National Institute for Physics and Nuclear Engineering, P.O. Box MG-6, Bucharest (Romania); Laboratori Nazionali di Legnaro, INFN, Legnaro (Italy); Neyens, G.; Vyvey, K. [IKS, University of Leuven, Celestijnenlaan 200 D, B-3001, Leuven (Belgium); Rainovski, G. [Faculty of Physics, St. Kliment Ohridski University of Sofia, BG-1164, Sofia (Bulgaria); Department of Physics, University of Liverpool, L69 7ZE, Liverpool (United Kingdom); Ur, C.A. [National Institute for Physics and Nuclear Engineering, P.O. Box MG-6, Bucharest (Romania); Dipartimento di Fisica dell' Universita di Padova and INFN, Sezione di Padova, Padova (Italy); Frauendorf, S.

    2004-04-01

    The quadrupole interaction of high-spin isomers in {sup 193}Pb implanted into solid Hg cooled at a temperature T=170 K has been investigated by the time-differential perturbed {gamma}-ray angular-distribution method. Spectroscopic quadrupole moment values of vertical stroke Q{sub s} vertical stroke =0.22(2) eb and 0.45(4) eb have been deduced for the 21/2{sup -} and 33/2{sup +} three-neutron states, respectively. A much higher value vertical stroke Q{sub s} vertical stroke =2.84(26) eb has been determined for the 29/2{sup -} isomer, the band head of a magnetic rotational band. (orig.)

  12. Photon strength functions in 177Lu: Study of scissors resonance in high-spin region

    Directory of Open Access Journals (Sweden)

    Bečvář F.

    2015-01-01

    Full Text Available The nucleus 177Lu is characteristic by an unusually high value of the thermal-neutron capturing state spin, J = 13/2, and by distinct low-energy rotational bands built on the 7/2+ ground state and the 9/2− level at 150 keV. The γ cascades connecting the capturing state with the members of these bands carry unique information about the role of identical M1 scissors-mode resonances, built according to Brink hypothesis assumingly on each energy level, even in conditions of fast nuclear rotation. With this motivation we measured a set of spectra of two-step γ cascades following the thermal neutron capture in 176Lu. The measurement was performed at neutron beam of the LWR-15 Reactor in Řež. From the analysis of these spectra the common parameters of the scissors resonances were deduced. The obtained results are discussed.

  13. Convergence of electronic bands for high performance bulk thermoelectrics.

    Science.gov (United States)

    Pei, Yanzhong; Shi, Xiaoya; LaLonde, Aaron; Wang, Heng; Chen, Lidong; Snyder, G Jeffrey

    2011-05-01

    Thermoelectric generators, which directly convert heat into electricity, have long been relegated to use in space-based or other niche applications, but are now being actively considered for a variety of practical waste heat recovery systems-such as the conversion of car exhaust heat into electricity. Although these devices can be very reliable and compact, the thermoelectric materials themselves are relatively inefficient: to facilitate widespread application, it will be desirable to identify or develop materials that have an intensive thermoelectric materials figure of merit, zT, above 1.5 (ref. 1). Many different concepts have been used in the search for new materials with high thermoelectric efficiency, such as the use of nanostructuring to reduce phonon thermal conductivity, which has led to the investigation of a variety of complex material systems. In this vein, it is well known that a high valley degeneracy (typically ≤6 for known thermoelectrics) in the electronic bands is conducive to high zT, and this in turn has stimulated attempts to engineer such degeneracy by adopting low-dimensional nanostructures. Here we demonstrate that it is possible to direct the convergence of many valleys in a bulk material by tuning the doping and composition. By this route, we achieve a convergence of at least 12 valleys in doped PbTe(1-x)Se(x) alloys, leading to an extraordinary zT value of 1.8 at about 850 kelvin. Band engineering to converge the valence (or conduction) bands to achieve high valley degeneracy should be a general strategy in the search for and improvement of bulk thermoelectric materials, because it simultaneously leads to a high Seebeck coefficient and high electrical conductivity.

  14. Substrate-supported large-band-gap quantum spin Hall insulator based on III-V bismuth layers

    Science.gov (United States)

    Padilha, J. E.; Janotti, A.; Fazzio, A.; da Silva, A. J. R.

    2016-11-01

    We show that III-V bismuth-based two-dimensional (2D) materials grown on an anion-terminated SrTe (111) substrate are 2D topological insulators. The III-Bi layers exhibit large nontrivial band gaps, ranging from 0.15 to 0.72 eV, depending on the passivation on the top surface, i.e., using hydrogen or halogens. We find that Γ -centered Dirac helical states, protected by time-reversal symmetry, appear at the edges of nanoribbon structures made of III-Bi layers on the SrTe substrate. The nontrivial character of the band gap is also determined by calculations of the Z2 invariant. We also find that the topological phase is maintained in the ultrathin quantum well heterostructures SrTe/III-Bi/SrTe, i.e., when the 2D materials are sandwiched between SrTe along the [111] direction, opening a new route for the fabrication of nanostructured devices based on 2D quantum spin Hall insulators.

  15. STUDY OF THE HIGH-SPIN STRUCTURE OF PM-146

    NARCIS (Netherlands)

    RZACAURBAN, T; DURELL, JL; PHILLIPS, WR; VARLEY, BJ; HESS, CP; PEARSON, CJ; VERMEER, WJ; VIEU, C; DIONISIO, JS; PAUTRAT, M; Urban, W

    1995-01-01

    Excited states in Pm-146 have been investigated through the Xe-136(N-15,5n) and the Nd-146(d,xn) compound-nucleus reactions. A level scheme extending up to 6.9 MeV of excitation energy and (I = 25HBAR) is proposed. Most of the high-spin levels are interpreted in terms of multi-particle-hole states b

  16. High-mobility ultrathin semiconducting films prepared by spin coating.

    Science.gov (United States)

    Mitzi, David B; Kosbar, Laura L; Murray, Conal E; Copel, Matthew; Afzali, Ali

    2004-03-18

    The ability to deposit and tailor reliable semiconducting films (with a particular recent emphasis on ultrathin systems) is indispensable for contemporary solid-state electronics. The search for thin-film semiconductors that provide simultaneously high carrier mobility and convenient solution-based deposition is also an important research direction, with the resulting expectations of new technologies (such as flexible or wearable computers, large-area high-resolution displays and electronic paper) and lower-cost device fabrication. Here we demonstrate a technique for spin coating ultrathin (approximately 50 A), crystalline and continuous metal chalcogenide films, based on the low-temperature decomposition of highly soluble hydrazinium precursors. We fabricate thin-film field-effect transistors (TFTs) based on semiconducting SnS(2-x)Se(x) films, which exhibit n-type transport, large current densities (>10(5) A cm(-2)) and mobilities greater than 10 cm2 V(-1) s(-1)--an order of magnitude higher than previously reported values for spin-coated semiconductors. The spin-coating technique is expected to be applicable to a range of metal chalcogenides, particularly those based on main group metals, as well as for the fabrication of a variety of thin-film-based devices (for example, solar cells, thermoelectrics and memory devices).

  17. High origin of the anterior band of the inferior glenohumeral ligament: MR arthrography with anatomic and histologic correlation in cadavers

    Energy Technology Data Exchange (ETDEWEB)

    Ramirez Ruiz, Francisco Alejandro [University of California and VA healthcare system, Department of Radiology, Musculoskeletal Division, San Diego, CA (United States); University of California and VA healthcare system, San Diego, CA (United States); Hospital Pablo Tobon Uribe, Departamento de Radiologia, Medellin (Colombia); Baranski Kaniak, Beatriz Cristina; Trudell, Debra; Resnick, Donald L. [University of California and VA healthcare system, Department of Radiology, Musculoskeletal Division, San Diego, CA (United States); Haghighi, Parviz [University of California and VA healthcare system, Department of Radiology, Musculoskeletal Division, San Diego, CA (United States); University of California San Diego, VA Healthcare System Dan Diego, Department of Pathology, San Diego, CA (United States)

    2012-05-15

    The anterior band of the inferior glenohumeral ligament has been described to arise from the anteroinferior labrum, but we have observed that in some persons its origin is from the anterior or anterosuperior labrum, creating diagnostic difficulties. Ten fresh unembalmed cadaveric shoulders underwent magnetic resonance arthrography (MRA) using a posterior approach with a 1.5 T GE magnet, with the following sequences: T1-weighted fast spin-echo in axial, coronal and sagittal planes, and T1 fat-suppressed spin-echo in the axial plane (TR/TE 600/20, section thickness 2.5 mm, 0.5 mm interslice space, number of signals acquired, two, field of view 12 x 12 cm, and matrix 512 x 256 pixels). Following imaging, the shoulders were frozen and later sectioned using a band saw into 3-mm sections corresponding to the axial imaging plane. Histological analysis was also performed to determine the origin of the anterior band. Four of the ten shoulders had an origin of the anterior band above or at the 3 o'clock position: one at the 1 o'clock position, two at the 2 o'clock position, and one at the 3 o'clock position. In another shoulder, the anterior band of the inferior glenohumeral ligament originated from the middle glenohumeral ligament, and in five other shoulders, the anterior band originated from the anteroinferior labrum as has been described in the literature. This finding is of clinical significance as a high origin of the anterior band of the inferior glenohumeral ligament leads to MR arthrographic finding that can simulate those of labral tears or detachments. (orig.)

  18. Decay out of the yrast and excited highly-deformed bands in the even-even nucleus {sup 134}Nd

    Energy Technology Data Exchange (ETDEWEB)

    Petrache, C.M.; Bazzacco, D.; Lunardi, S. [Sezione di Padova (Italy)] [and others

    1996-12-31

    The resolving power achieved by the new generation of {gamma}-ray detector arrays allows now to observe transitions with intensities of the order of {approximately}10{sup {minus}3} of the population of the final residual nucleus, making therefore feasible the study of the very weakly populated excited bands built on the superdeformed (SD) minimum or of the decay out of the SD bands. As a matter of fact, numerous excited SD bands have been observed in the different regions of superdeformation, which led to a deeper understanding of the single-particle excitation in the second minimum. The first experimental breakthrough in the study of the decay out process has been achieved in the odd-even {sup 133,135}Nd nuclei of the A=130 mass region. There, the observation of the discrete linking transitions has been favored by the relatively higher intensity of the highly-deformed (HD) bands ({approximately}10%), as well as by the small excitation energy with respect to the yrast line in the decay-out region ({approximately}1 MeV). No discrete linking transitions have been so far observed in the A=80, 150 mass regions. The present results suggest that the decay out of the HD bands in {sup 134}Nd is triggered by the crossing with the N=4 [402]5/2{sup +} Nilsson orbital, that has a smaller deformation than the corresponding N=6 intruder configuration. The crossing favours the mixing with the ND rotational bands strongly enhancing the decay-out process and weakening the in-band transition strength. The HD band becomes fragmented and looses part of its character. The intensity of the decay-out transitions increases when the spin of the HD state decreases, indicating enhanced ND amplitude in the wavefunction when going down the band. Lifetime measurements of the HD bands are crucial to further elucidate the decay-out process.

  19. High Frequency QPOs due to Black Hole Spin

    Science.gov (United States)

    Kazanas, Demos; Fukumura, K.

    2009-01-01

    We present detailed computations of photon orbits emitted by flares at the innermost stable circular orbit (ISCO) of accretion disks around rotating black holes. We show that for sufficiently large spin parameter, i.e. a > 0.94 M, flare a sufficient number of photons arrive at an observer after multiple orbits around the black hole, to produce an "photon echo" of constant lag, i.e. independent of the relative phase between the black hole and the observer, of T approximates 14 M. This constant time delay, then, leads to a power spectrum with a QPO at a frequency nu approximates 1/14M, even for a totally random ensemble of such flares. Observation of such a QPO will provide incontrovertible evidence for the high spin of the black hole and a very accurate, independent, measurement of its mass.

  20. High Frequency QPOs due to Black Hole Spin

    Science.gov (United States)

    Kazanas, Demos; Fukumura, K.

    2009-01-01

    We present detailed computations of photon orbits emitted by flares at the innermost stable circular orbit (ISCO) of accretion disks around rotating black holes. We show that for sufficiently large spin parameter, i.e. a > 0.94 M, flare a sufficient number of photons arrive at an observer after multiple orbits around the black hole, to produce an "photon echo" of constant lag, i.e. independent of the relative phase between the black hole and the observer, of T approximates 14 M. This constant time delay, then, leads to a power spectrum with a QPO at a frequency nu approximates 1/14M, even for a totally random ensemble of such flares. Observation of such a QPO will provide incontrovertible evidence for the high spin of the black hole and a very accurate, independent, measurement of its mass.

  1. High current gain silicon-based spin transistor

    CERN Document Server

    Dennis, C L; Ensell, G J; Gregg, J F; Thompson, S M

    2003-01-01

    A silicon-based spin transistor of novel operating principle has been demonstrated in which the current gain at room temperature is 1.4 (n-type) and 0.97 (p-type). This high current gain was obtained from a hybrid metal/semiconductor analogue to the bipolar junction transistor which functions by tunnel-injecting carriers from a ferromagnetic emitter into a diffusion driven silicon base and then tunnel-collecting them via a ferromagnetic collector. The switching of the magnetic state of the collector ferromagnet controls the collector efficiency and the current gain. Furthermore, the magnetocurrent, which is determined to be 98% (140%) for p-type (n-type) in -110 Oe, is attributable to the spin-polarized base diffusion current.

  2. A 3D-printed high power nuclear spin polarizer.

    Science.gov (United States)

    Nikolaou, Panayiotis; Coffey, Aaron M; Walkup, Laura L; Gust, Brogan M; LaPierre, Cristen D; Koehnemann, Edward; Barlow, Michael J; Rosen, Matthew S; Goodson, Boyd M; Chekmenev, Eduard Y

    2014-01-29

    Three-dimensional printing with high-temperature plastic is used to enable spin exchange optical pumping (SEOP) and hyperpolarization of xenon-129 gas. The use of 3D printed structures increases the simplicity of integration of the following key components with a variable temperature SEOP probe: (i) in situ NMR circuit operating at 84 kHz (Larmor frequencies of (129)Xe and (1)H nuclear spins), (ii) 3D printing dramatically reduces production time and expenses while allowing reproducibility and integration of "off-the-shelf" components and enables the concept of printing on demand. The utility of this SEOP setup is demonstrated here to obtain near-unity (129)Xe polarization values in a 0.5 L optical pumping cell, including ∼74 ± 7% at 1000 Torr xenon partial pressure, a record value at such high Xe density. Values for the (129)Xe polarization exponential build-up rate [(3.63 ± 0.15) × 10(-2) min(-1)] and in-cell (129)Xe spin-lattice relaxation time (T1 = 2.19 ± 0.06 h) for 1000 Torr Xe were in excellent agreement with the ratio of the gas-phase polarizations for (129)Xe and Rb (PRb ∼ 96%). Hyperpolarization-enhanced (129)Xe gas imaging was demonstrated with a spherical phantom following automated gas transfer from the polarizer. Taken together, these results support the development of a wide range of chemical, biochemical, material science, and biomedical applications.

  3. High Power High Efficiency Ka-Band Power Combiners for Solid-State Devices

    Science.gov (United States)

    Freeman, Jon C.; Wintucky, Edwin G.; Chevalier, Christine T.

    2006-01-01

    Wide-band power combining units for Ka-band are simulated for use as MMIC amplifier applications. Short-slot couplers as well as magic-tees are the basic elements for the combiners. Wide bandwidth (5 GHz) and low insertion (approx.0.2 dB) and high combining efficiencies (approx.90 percent) are obtained.

  4. Collective Band Structures in Neutron-Rich 108Mo Nucleus

    Institute of Scientific and Technical Information of China (English)

    DING Huai-Bo; WANG Jian-Guo; XU Qiang; ZHU Sheng-Jiang; J. H. Hamilton; A. V. Ramayya; J. K. Hwang; Y. X. Luo; J. O. Rasmussen; I. Y. Lee; CHE Xing-Lai

    2007-01-01

    High spin states in the neutron-rich 108Mo nucleus are studied by measuring prompt γ-rays following the spontaneous fission of 252Cf with a Gammasphere detector array. The ground-state band is confirmed, and the one-phonon γ-vibrational band is updated with spin up to 12 h. A new collective band with the band head level at 1422.4 keV is suggested as a two-phonon γ-vibrational band. Another new band is proposed as a two-quasi-proton excitation band. Systematic characteristics of the collective bands are discussed.

  5. Thermal destruction of spin-polaron bands in the narrow-gap correlated semiconductors FeGa3 and FeSb2

    Science.gov (United States)

    Storchak, Vyacheslav G.; Brewer, Jess H.; Lichti, Roger L.; Hu, Rongwei; Petrovic, Cedomir

    2012-05-01

    We report muon spin rotation spectra in the narrow-gap semiconductors FeGa3 and FeSb2 consistent with a narrow band of small spin polarons (SPs). The characteristic sizes obtained for these SPs are RFeGa3 ≈ 0.3-0.6 nm and RFeSb 2 ≈ 0.3 nm, respectively. Such SP states are expected to originate from the exchange correlations between localized and itinerant electrons. Our data suggest that SP bands are formed at low temperature, but are destroyed by thermal fluctuations above 10 K in FeGa3 and above 7 K in FeSb2. Formation of such SP band states can explain many of the low-temperature properties of these materials.

  6. Thermal Destruction of Spin-polaron Bands in the Narrow-gap Correlated Semiconductors FeGa3 and FeSb2

    Energy Technology Data Exchange (ETDEWEB)

    Petrovic C.; Storchak, V.G.; Brewer, J.S.; Lichti, R.L.; Hu, R.

    2012-04-05

    We report muon spin rotation spectra in the narrow-gap semiconductors FeGa{sub 3} and FeSb{sub 2} consistent with a narrow band of small spin polarons (SPs). The characteristic sizes obtained for these SPs are R{sub FeGa{sub 3}} {approx} 0.3-0.6 nm and R{sub FeSb{sub 2}} {approx} 0.3 nm, respectively. Such SP states are expected to originate from the exchange correlations between localized and itinerant electrons. Our data suggest that SP bands are formed at low temperature, but are destroyed by thermal fluctuations above 10 K in FeGa{sub 3} and above 7 K in FeSb{sub 2}. Formation of such SP band states can explain many of the low-temperature properties of these materials.

  7. Dark state adiabatic passage with branched networks and high-spin systems: spin separation and entanglement

    Directory of Open Access Journals (Sweden)

    Caitlin eBatey

    2015-09-01

    Full Text Available Adiabatic methods are potentially important for quantum information protocols because of their robustness against many sources of technical and fundamental noise. They are particularly useful for quantum transport, and in some cases elementary quantum gates. Here we explore the extension of a particular protocol, dark state adiabatic passage, where a spin state is transported across a branched network of initialised spins, comprising one `input' spin, and multiple leaf spins. We find that maximal entanglement is generated in systems of spin-half particles, or where the system is limited to one excitation.

  8. Ultrahigh Spin Structures in 157,158,159Er

    Institute of Scientific and Technical Information of China (English)

    MA Hai-Liang; DONG Bao-Guo; YAN Yu-Liang

    2008-01-01

    Rotational structures at ultrahigh spin in 157'158'159Er have been investigated with the configuration-dependent cranked Nilsson-Strutinsky approach. Configurations of observed bands are assigned and the corresponding deformations are given theoretically. The calculations suggest that one of ultrahigh spin bands in 158Er is triaxial highly deformed and the other is normal-deformed, while both ultrahigh spin bands in 157Er are suggested to be triaxial highly deformed. The possible ultrahigh spin bands in l59Er are predicted to be triaxial highly deformed and have shape coexistence in the same configuration. The configurations with two neutron holes in the Nosc=4 orbitals and two neutron holes in the h11/2 orbitals in 159Er are favoured for ultrahigh spin states but unfavoured for band termination, which is similar to ultrahigh spin bands in 157,158Er.

  9. High frequency spin torque oscillators with composite free layer spin valve

    Energy Technology Data Exchange (ETDEWEB)

    Natarajan, Kanimozhi; Arumugam, Brinda; Rajamani, Amuda

    2016-07-15

    We report the oscillations of magnetic spin components in a composite free layer spin valve. The associated Landau–Lifshitz–Gilbert–Slonczewski (LLGS) equation is studied by stereographically projecting the spin on to a complex plane and the spin components were found. A fourth order Runge–Kutta numerical integration on LLGS equation also confirms the similar trajectories of the spin components. This study establishes the possibility of a Spin Torque Oscillator in a composite free layer spin valve, where the exchange coupling is ferromagnetic in nature. In-plane and out-of-plane precessional modes of magnetization oscillations were found in zero applied magnetic field and the frequencies of the oscillations were calculated from Fast Fourier Transform of the components of magnetization. Behavior of Power Spectral Density for a range of current density is studied. Finally our analysis shows the occurrence of highest frequency 150 GHz, which is in the second harmonics for the specific choice of system parameters.

  10. High frequency spin torque oscillators with composite free layer spin valve

    Science.gov (United States)

    Natarajan, Kanimozhi; Arumugam, Brinda; Rajamani, Amuda

    2016-07-01

    We report the oscillations of magnetic spin components in a composite free layer spin valve. The associated Landau-Lifshitz-Gilbert-Slonczewski (LLGS) equation is studied by stereographically projecting the spin on to a complex plane and the spin components were found. A fourth order Runge-Kutta numerical integration on LLGS equation also confirms the similar trajectories of the spin components. This study establishes the possibility of a Spin Torque Oscillator in a composite free layer spin valve, where the exchange coupling is ferromagnetic in nature. In-plane and out-of-plane precessional modes of magnetization oscillations were found in zero applied magnetic field and the frequencies of the oscillations were calculated from Fast Fourier Transform of the components of magnetization. Behavior of Power Spectral Density for a range of current density is studied. Finally our analysis shows the occurrence of highest frequency 150 GHz, which is in the second harmonics for the specific choice of system parameters.

  11. Band anticrossing effects in highly mismatched semiconductor alloys

    Science.gov (United States)

    Wu, Junqiao

    The first five chapters of this thesis focus on studies of band anticrossing (BAC) effects in highly electronegativity-mismatched semiconductor alloys. The concept of bandgap bowing has been used to describe the deviation of the alloy bandgap from a linear interpolation. Bowing parameters as large as 2.5 eV (for ZnSTe) and close to zero (for AlGaAs and ZnSSe) have been observed experimentally. Recent advances in thin film deposition techniques have allowed the growth of semiconductor alloys composed of significantly different constituents with ever-improving crystalline quality (e.g., GaAs1-xNx and GaP1-xNx with x bandgap bowing (bowing parameters >14 eV). A band anticrossing model has been developed to explain these properties. The model shows that the predominant bowing mechanism in these systems is driven by the anticrossing interaction between the localized level associated with the minority component and the band states of the host. In this thesis I discuss my studies of the BAC effects in these highly mismatched semiconductors. It will be shown that the results of the physically intuitive BAC model can be derived from the Hamiltonian of the many-impurity Anderson model. The band restructuring caused by the BAC interaction is responsible for a series of experimental observations such as a large bandgap reduction, an enhancement of the electron effective mass, and a decrease in the pressure coefficient of the fundamental gap energy. Results of further experimental investigations of the optical properties of quantum wells based on these materials will be also presented. It will be shown that the BAC interaction occurs not only between localized states and conduction band states at the Brillouin zone center, but also exists over all of k-space. Finally, taking ZnSTe and ZnSeTe as examples, I show that BAC also occurs between localized states and the valence band states. Soft x-ray fluorescence experiments provide direct evidence of the BAC interaction in these

  12. Band anticrossing effects in highly mismatched semiconductor alloys

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Junqiao [Univ. of California, Berkeley, CA (United States)

    2002-01-01

    The first five chapters of this thesis focus on studies of band anticrossing (BAC) effects in highly electronegativity- mismatched semiconductor alloys. The concept of bandgap bowing has been used to describe the deviation of the alloy bandgap from a linear interpolation. Bowing parameters as large as 2.5 eV (for ZnSTe) and close to zero (for AlGaAs and ZnSSe) have been observed experimentally. Recent advances in thin film deposition techniques have allowed the growth of semiconductor alloys composed of significantly different constituents with ever- improving crystalline quality (e.g., GaAs1-xNx and GaP1-xNx with x ~< 0.05). These alloys exhibit many novel and interesting properties including, in particular, a giant bandgap bowing (bowing parameters > 14 eV). A band anticrossing model has been developed to explain these properties. The model shows that the predominant bowing mechanism in these systems is driven by the anticrossing interaction between the localized level associated with the minority component and the band states of the host. In this thesis I discuss my studies of the BAC effects in these highly mismatched semiconductors. It will be shown that the results of the physically intuitive BAC model can be derived from the Hamiltonian of the many-impurity Anderson model. The band restructuring caused by the BAC interaction is responsible for a series of experimental observations such as a large bandgap reduction, an enhancement of the electron effective mass, and a decrease in the pressure coefficient of the fundamental gap energy. Results of further experimental investigations of the optical properties of quantum wells based on these materials will be also presented. It will be shown that the BAC interaction occurs not only between localized states and conduction band states at the Brillouin zone center, but also exists over all of k-space. Finally, taking ZnSTe and ZnSeTe as examples, I show that BAC also

  13. Band anticrossing effects in highly mismatched semiconductor alloys

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Junqiao

    2002-09-09

    The first five chapters of this thesis focus on studies of band anticrossing (BAC) effects in highly electronegativity- mismatched semiconductor alloys. The concept of bandgap bowing has been used to describe the deviation of the alloy bandgap from a linear interpolation. Bowing parameters as large as 2.5 eV (for ZnSTe) and close to zero (for AlGaAs and ZnSSe) have been observed experimentally. Recent advances in thin film deposition techniques have allowed the growth of semiconductor alloys composed of significantly different constituents with ever- improving crystalline quality (e.g., GaAs{sub 1-x}N{sub x} and GaP{sub 1-x}N{sub x} with x {approx}< 0.05). These alloys exhibit many novel and interesting properties including, in particular, a giant bandgap bowing (bowing parameters > 14 eV). A band anticrossing model has been developed to explain these properties. The model shows that the predominant bowing mechanism in these systems is driven by the anticrossing interaction between the localized level associated with the minority component and the band states of the host. In this thesis I discuss my studies of the BAC effects in these highly mismatched semiconductors. It will be shown that the results of the physically intuitive BAC model can be derived from the Hamiltonian of the many-impurity Anderson model. The band restructuring caused by the BAC interaction is responsible for a series of experimental observations such as a large bandgap reduction, an enhancement of the electron effective mass, and a decrease in the pressure coefficient of the fundamental gap energy. Results of further experimental investigations of the optical properties of quantum wells based on these materials will be also presented. It will be shown that the BAC interaction occurs not only between localized states and conduction band states at the Brillouin zone center, but also exists over all of k-space. Finally, taking ZnSTe and ZnSeTe as examples, I show that BAC also occurs between

  14. Highly viscous fluid flow in a spinning and nutating cylinder

    Science.gov (United States)

    Herbert, T.

    1985-02-01

    Spin-stabilized projectiles with liquid payloads can experience a severe flight instability characterized by a rapid yaw angle growth and a simultaneous loss in spin rate. Laboratory experiments and field tests have shown that this instability originates from the internal fluid motion in the range of high viscosity. Evaluation of the experimental data and analysis of the equations for the fluid motion in a spinning and nutating cylinder suggest a theoretical approach in three major steps: (1) analysis of the steady viscous flow in an infinitely long cylinder, (2) hydrodynamic stability analysis of this basic flow, and (3) analysis of the end effects. The basic flow has been found in analytical form. At low Reynolds number, this flow agrees well with computational results for the center section of a cylinder of aspect ratio 4.3. The despin moment caused by this flow largely agrees with experimental data for a wide range of Reynolds numbers. Current work aims at the stability of this flow.

  15. Wide-Band, High-Quantum-Efficiency Photodetector

    Science.gov (United States)

    Jackson, Deborah; Wilson, Daniel; Stern, Jeffrey

    2007-01-01

    A design has been proposed for a photodetector that would exhibit a high quantum efficiency (as much as 90 percent) over a wide wavelength band, which would typically be centered at a wavelength of 1.55 m. This and similar photodetectors would afford a capability for detecting single photons - a capability that is needed for research in quantum optics as well as for the practical development of secure optical communication systems for distribution of quantum cryptographic keys. The proposed photodetector would be of the hot-electron, phonon-cooled, thin-film superconductor type. The superconducting film in this device would be a meandering strip of niobium nitride. In the proposed photodetector, the quantum efficiency would be increased through incorporation of optiA design has been proposed for a photodetector that would exhibit a high quantum efficiency (as much as 90 percent) over a wide wavelength band, which would typically be centered at a wavelength of 1.55 m. This and similar photodetectors would afford a capability for detecting single photons - a capability that is needed for research in quantum optics as well as for the practical development of secure optical communication systems for distribution of quantum cryptographic keys. The proposed photodetector would be of the hot-electron, phonon-cooled, thin-film superconductor type. The superconducting film in this device would be a meandering strip of niobium nitride. In the proposed photodetector, the quantum efficiency would be increased through incorporation of opti-

  16. High-resolution study of nuclear magnetic relaxation dispersion of purine nucleotides: effects of spin-spin coupling.

    Science.gov (United States)

    Kiryutin, Alexey; Ivanov, Konstantin; Yurkovskaya, Alexandra; Vieth, Hans-Martin

    2008-01-01

    By combining magnetic field cycling in the range from 0.1mT to 7T with high-resolution NMR detection the T(1) relaxation dispersion (nuclear magnetic relaxation dispersion (NMRD)) of protons in the nucleotides adenosine mono-phosphate and guanosine mono-phosphate was measured in a site-specific way. While at high field the individual spins have distinctly different T(1) times, their scalar spin-spin interaction fulfills at low field the condition of strong coupling and leads to convergence of their T(1) dispersion curves. In addition, the spin-spin coupling can lead to oscillatory components in the relaxation kinetics traceable to a coupling between spin polarization and coherence in the relaxation process. As a consequence the NMRD curves do not directly reflect the spectral density function of the motional processes, but the effects of motion and spin coupling must be separated for a reliable evaluation. A theoretical approach is described allowing such an analysis.

  17. Cation-induced band-gap tuning in organohalide perovskites: interplay of spin-orbit coupling and octahedra tilting.

    Science.gov (United States)

    Amat, Anna; Mosconi, Edoardo; Ronca, Enrico; Quarti, Claudio; Umari, Paolo; Nazeeruddin, Md K; Grätzel, Michael; De Angelis, Filippo

    2014-06-11

    Organohalide lead perovskites have revolutionized the scenario of emerging photovoltaic technologies. The prototype MAPbI3 perovskite (MA = CH3NH3(+)) has dominated the field, despite only harvesting photons above 750 nm (∼1.6 eV). Intensive research efforts are being devoted to find new perovskites with red-shifted absorption onset, along with good charge transport properties. Recently, a new perovskite based on the formamidinium cation ((NH2)2CH(+) = FA) has shown potentially superior properties in terms of band gap and charge transport compared to MAPbI3. The results have been interpreted in terms of the cation size, with the larger FA cation expectedly delivering reduced band-gaps in Pb-based perovskites. To provide a full understanding of the interplay among size, structure, and organic/inorganic interactions in determining the properties of APbI3 perovskites, in view of designing new materials and fully exploiting them for solar cells applications, we report a fully first-principles investigation on APbI3 perovskites with A = Cs(+), MA, and FA. Our results evidence that the tetragonal-to-quasi cubic structural evolution observed when moving from MA to FA is due to the interplay of size effects and enhanced hydrogen bonding between the FA cations and the inorganic matrix altering the covalent/ionic character of Pb-I bonds. Most notably, the observed cation-induced structural variability promotes markedly different electronic and optical properties in the MAPbI3 and FAPbI3 perovskites, mediated by the different spin-orbit coupling, leading to improved charge transport and red-shifted absorption in FAPbI3 and in general in pseudocubic structures. Our theoretical model constitutes the basis for the rationale design of new and more efficient organohalide perovskites for solar cells applications.

  18. One-hundred-three compound band-structure benchmark of post-self-consistent spin-orbit coupling treatments in density functional theory

    Science.gov (United States)

    Huhn, William P.; Blum, Volker

    2017-08-01

    We quantify the accuracy of different non-self-consistent and self-consistent spin-orbit coupling (SOC) treatments in Kohn-Sham and hybrid density functional theory by providing a band-structure benchmark set for the valence and low-lying conduction energy bands of 103 inorganic compounds, covering chemical elements up to polonium. Reference energy band structures for the PBE density functional are obtained using the full-potential (linearized) augmented plane wave code wien2k, employing its self-consistent treatment of SOC including Dirac-type p1 /2 orbitals in the basis set. We use this benchmark set to benchmark a computationally simpler, non-self-consistent all-electron treatment of SOC based on scalar-relativistic orbitals and numeric atom-centered orbital basis functions. For elements up to Z ≈50 , both treatments agree virtually exactly. For the heaviest elements considered (Tl, Pb, Bi, Po), the band-structure changes due to SOC are captured with a relative deviation of 11% or less. For different density functionals (PBE versus the hybrid HSE06), we show that the effect of spin-orbit coupling is usually similar but can be dissimilar if the qualitative features of the predicted underlying scalar-relativistic band structures do not agree. All band structures considered in this work are available online via the NOMAD repository to aid in future benchmark studies and methods development.

  19. High Resolution Photoacoustic Spectroscopy of the Oxygen A-Band

    Science.gov (United States)

    Cich, Matthew J.; Lunny, Elizabeth M.; Stroscio, Gautam; Bui, Thinh Quoc; Bray, Caitlin; Hogan, Daniel; Rupasinghe, Priyanka; Crawford, Timothy J.; Drouin, Brian; Miller, Charles; Long, David A.; Hodges, Joseph T.; Okumura, Mitchio

    2016-06-01

    NASA's Orbiting Carbon Observatory missions require spectroscopic parameterization of the Oxygen A-Band absorption (757-775 nm) with unprecedented detail to meet the objective of delivering space-based column CO2 measurements with an accuracy of better than 1 ppm, and spectroscopic parameters with accuracies at the 0.1% level. To achieve this it is necessary for line shape models to include deviations from the Voigt line shape, including the collisional effects of speed-dependence, line mixing (LM), and collision-induced absorption (CIA). LM and CIA have been difficult to quantify in FTIR and CRDS spectra which have been limited to lower pressure measurements. A photoacoustic spectrometer has been designed to study the pressure- dependence of the spectral line shape up to pressures of 5 atm, where LM and CIA contribute significantly to the A-Band absorption. This spectrometer has a high signal-to-noise (S/N) of about 10,000 and frequency accuracy of 2 MHz. In addition, temperature-dependent effects on the line shape are studied using PID-controlled cooled nitrogen flow/ heater system. The latest acquired spectra and analysis are reported here.

  20. New high-spin level schemes and excitation modes of {sup 117,118,119,120,122}Cd

    Energy Technology Data Exchange (ETDEWEB)

    Luo, Y.X. [Physics Department, Vanderbilt University, Nashville, TN 37235 (United States); Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Rasmussen, J.O., E-mail: jorasmussen@lbl.gov [Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Department of Chemistry, U.C. Berkeley, Berkeley, CA 94720 (United States); Nelson, C.S.; Hamilton, J.H.; Ramayya, A.V.; Hwang, J.K. [Physics Department, Vanderbilt University, Nashville, TN 37235 (United States); Liu, S.H. [Physics Department, Vanderbilt University, Nashville, TN 37235 (United States); Joint Institute for Heavy Ion Research, Oak Ridge, TN 37831 (United States); Goodin, C. [Physics Department, Vanderbilt University, Nashville, TN 37235 (United States); Stone, N.J. [Department of Physics, Oxford University, Oxford OX1 3PU (United Kingdom); Department of Physics and Astronomy, University of Tennessee, Knoxville, TN 37996 (United States); Zhu, S.J. [Physics Department, Vanderbilt University, Nashville, TN 37235 (United States); Department of Physics, Tsinghua University, Beijing 100084 (China); Brewer, N.T.; Li Ke [Physics Department, Vanderbilt University, Nashville, TN 37235 (United States); Lee, I.Y. [Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Ter-Akopian, G.M. [Flerov Laboratory for Nuclear Reactions, JINR, Dubna (Russian Federation); Daniel, A.V. [Physics Dept., Vanderbilt University, Nashville, TN 37235 (United States); Flerov Laboratory for Nuclear Reactions, JINR, Dubna (Russian Federation); Joint Inst. for Heavy Ion Research, Oak Ridge, TN 37831 (United States); Stoyer, M.A. [Lawrence Livermore National Lab., Livermore, CA 94550 (United States); Donangelo, R. [Facultad de Ingenieria, C.C.30, 11300 Montevideo (Uruguay); Ma, W.C. [Mississippi State Univ., Drawer 5167, Mississippi State, MS 39762 (United States); Cole, J.D. [Idaho National Laboratory, Bldg. IRCPL, MS2114, Idaho Falls, ID 83415 (United States)

    2012-01-15

    High-spin level schemes of {sup 117,118,119,120,122}Cd are expanded by analyzing our high-statistics triple- and higher-fold coincidence events of prompt fission {gamma} rays from {sup 252}Cf at Gammasphere. Spin/parity assignments were made based on new {gamma}-{gamma} angular correlation measurements and level systematics in the neighboring isotopes. Stretch-aligned band structures observed in low-lying levels in {sup 117,119,121}Cd are seen to weaken with increasing spins, with a quasi-rotational degree of freedom manifested at higher spins. The 5{sup -} levels in even-N{sup 118,120}Cd were tentatively interpreted as candidates of quadrupole-octupole (QOC) coupling. The model-independent spin versus Planck-Constant-Over-Two-Pi {omega} curves for even-N and odd-N Cd isotopes imply quasi-rotational alignment of an h{sub 11/2} neutron pair in the even-N Cd isotopes. The relative energies of the lowest 11/2{sup -}, 9/2{sup -}, 7/2{sup -}, and 15/2{sup -} levels in {sup 117}Cd and {sup 119}Cd suggest triaxial shapes based on Meyer-Ter-Vehn theory for these odd-N Cd nuclei. For the even-N Cd isotopes evidence of triaxiality may also be provided by the Shell Correction version of the Tilted Axis Cranking model (SCTAC).

  1. High-spin {gamma}-ray spectroscopy of {sup 124}Ba, {sup 124}Xe and {sup 125}Xe

    Energy Technology Data Exchange (ETDEWEB)

    Al-Khatib, Ali

    2008-08-18

    rotational bands loose collectivity and, finally, when all nucleons outside the core have their spins aligned, the bands terminate. In the framework of this thesis, extensive spectroscopic investigations of three nuclei of the A {proportional_to}125 region, {sup 124}Ba, {sup 124}Xe and {sup 125}Xe, have been performed. These nuclei have been studied with the largest spectrometers available, Euroball and Gammasphere. The previously known level schemes of these nuclei have been extended substantially, both in the low- and high-spin regions. Many new rotational bands could be established. Lifetimes have been measured for several of the long large-deformation bands. The rotational structures, shape co-existence and band termination at high spins have been investigated. (orig.)

  2. Reinvestigation of the high spin states in ^(161)Er and enhanced E1 transitions in the N=93 isotones

    Institute of Scientific and Technical Information of China (English)

    陈亮; 周厚兵; 丁兵; 王海霞; 郑勇; 竺礼华; 吴晓光; 周小红; 张玉虎; 柳敏良; 王世陶; 方永得; 滑伟; 强赟华; 李广顺

    2011-01-01

    High-spin states in 161Er have been studied experimentally using the 150Nd(16O, 5n) reaction at a beam energy of 86 MeV. The relatively enhanced E1 transitions between the 5/2+[642] and 3/2-[521] bands are observed in 161Er, and the B(E1) values are extra

  3. Decay of a narrow and high spin {sup 24}Mg + {sup 24}Mg resonance

    Energy Technology Data Exchange (ETDEWEB)

    Salsac, M.-D. [IPHC, Universite Louis Pasteur, CNRS-IN2P3, Strasbourg (France)], E-mail: marie-delphine.salsac@ires.in2p3.fr; Haas, F.; Courtin, S. [IPHC, Universite Louis Pasteur, CNRS-IN2P3, Strasbourg (France); Algora, A. [INR, Debrecen (Hungary); Beck, C. [IPHC, Universite Louis Pasteur, CNRS-IN2P3, Strasbourg (France); Beghini, S. [Universita di Padova and INFN, Padova (Italy); Behera, B.R. [INFN Laboratori Nazionali di Legnaro, Legnaro (Italy); Chapman, R. [University of the West of Scotland, Paisley (United Kingdom); Corradi, L. [INFN Laboratori Nazionali di Legnaro, Legnaro (Italy); Dombradi, Z. [INR, Debrecen (Hungary); Farnea, E. [Universita di Padova and INFN, Padova (Italy); Fioretto, E.; Gadea, A. [INFN Laboratori Nazionali di Legnaro, Legnaro (Italy); Jenkins, D.G. [University of York, York (United Kingdom); Latina, A. [INFN Laboratori Nazionali di Legnaro, Legnaro (Italy); Lebhertz, D. [IPHC, Universite Louis Pasteur, CNRS-IN2P3, Strasbourg (France); Lenzi, S. [Universita di Padova and INFN, Padova (Italy); Liang, X. [University of the West of Scotland, Paisley (United Kingdom); Marginean, N. [INFN Laboratori Nazionali di Legnaro, Legnaro (Italy); Montagnoli, G. [Universita di Padova and INFN, Padova (Italy)] (and others)

    2008-03-01

    The {sup 24}Mg + {sup 24}Mg reaction has been studied at the Legnaro Tandem at a CM bombarding energy of 45.7 MeV where a narrow and high spin resonance has been reported previously. The decay of the resonance into the inelastic and fusion-evaporation channels has been investigated. The ON and OFF resonance decay yields have been measured using, for the inelastic channels, the fragment spectrometer PRISMA and the {gamma} array CLARA, and, for the fusion-evaporation channels, the Si array EUCLIDES and the {gamma} array GASP. Strong resonant effects have been observed in the inelastic channels involving the 2{sub 1}{sup +} and 4{sub 1}{sup +} states of the {sup 24}Mg ground state band. Weaker effects are also seen in certain fusion-evaporation channels. The properties of the studied resonance are in agreement with molecular model predictions. It is also proposed that the narrow and high spin {sup 24}Mg + {sup 24}Mg resonance corresponds to the formation of a fast rotating and highly prolate deformed {sup 48}Cr after a Jacobi shape transition and just before fission.

  4. High-spin states and signature inversion in odd-odd 182Au

    Institute of Scientific and Technical Information of China (English)

    ZHANG; Yuhu; (

    2003-01-01

    [1]Bengtsson, R., Frisk, R. H., May, R. F. et al., Signature inversion: a fingerprint of triaxiality, Nucl. Phys. A, 1984, 415: 189-214.[2]Zhang, Y. H., Hayakawa, T., Oshima, M. et al., Signature inversion in the rotational bands of odd-odd 178Ir, High Energy Phys. & Nucl. Phys. (in Chinese), 2000, 24(1): 1123-1130.[3]Xu, F. R., Satula, W., Wyss, R., Quadrupole pairing interaction and signature inversion, Nucl. Phys. A, 2000, 669: 119-134.[4]Zhang, Y. H., Zhao, Q. Z., Zhang, S. Q. et al., Experimental study of high-spin states in odd-odd nuclei around 160-180 mass region, High Energy Phys. & Nucl. Phys. (in Chinese), 2000, 24(supp): 21-28.[5]Zhang, Y. H., Oshima, M., Toh, Y. et al., Rotational bands and signature inversion phenomena in πh9/2(*)Vi13/2 and πi13/2(*)Vi13/2 structures in odd-odd 176Ir, Eur. Phys. J. A, 2002, 13(4): 429-433.[6]Zhang, Y. H., Hayakawa, T., Oshima, M. et al., Search for signature inversion in the πi13/2(*)Vi13/2 band in odd-odd 178Ir, Chin. Phys. Lett., 2001, 18 (10):1323-1326.[7]Zhang, Y. H., Hayakawa, T., Oshima, M. et al., Configuration-dependent band structure in odd-odd 180Ir, Phys. Rev. C, 2002, 65: 014302-1-014302-15.[8]Ibrahim, F., Genevey, J., Cottereau, E. et al., Low-spin states of doubly odd 182Au, Eur. Phys. J. A, 2001, 10(2): 139-143.[9]Mueller, W. F., Jin, H. Q., Lewis, J. M. et al., High-spin structure in 181,183Au, Phys. Rev. C, 1999, 59(4): 2009-2032.[10]De Voigt, M. J. A., Kaczarowski, R., Riezebos, H. J. et al., Rotational bands in 181Pt, Nucl. Phys. A, 1990, 507: 447-471.[11]Popescu, D. G., Waddington, J. C., Cameron, J. A. et al., High-spin states and band structures in 182Pt, Phys. Rev. C, 1997, 55(3): 1175-1191.[12]Jin, H. Q., Riedinger, L. L., Bingham, C. R. et al., Effects of intruder states in 179Ir, Phys. Rev. C, 1996, 53(5): 2106-2125.[13]Hojman, D., Cardona, M. A., Napoli, D. R. et al., Signature inversion in Vi13/2(*)Vi13/2 structure in 178Ir, Eur. Phys

  5. Control in Highly Focused Top-Spinning. Brief Report.

    Science.gov (United States)

    Berkson, Gershon

    1998-01-01

    Three studies analyzed stimulus feedback and the concept of control with three children and two adults having autism. The first study explored feedback from spinning tops, while the second and third emphasized control of various stimuli including spinning tops. Results indicate that autistic individuals' common interest in spinning tops is…

  6. Cavity Enhanced Optical Vernier Spectroscopy, Broad Band, High Resolution, High Sensitivity

    CERN Document Server

    Gohle, Christoph; Schliesser, Albert; Udem, Thomas; Hänsch, Theodor W

    2007-01-01

    A femtosecond frequency comb provides a vast number of equidistantly spaced narrow band laser modes that can be simultaneously tuned and frequency calibrated with 15 digits accuracy. Our Vernier spectrometer utilizes all of theses modes in a massively parallel manner to rapidly record both absorption and dispersion spectra with a sensitivity that is provided by a high finesse broad band optical resonator and a resolution that is only limited by the frequency comb line width while keeping the required setup simple.

  7. Spin polarization, orbital occupation and band gap opening in vanadium dioxide: The effect of screened Hartree-Fock exchange

    KAUST Repository

    Wang, Hao

    2014-07-01

    The metal-insulator transition of VO2 so far has evaded an accurate description by density functional theory. The screened hybrid functional of Heyd, Scuseria and Ernzerhof leads to reasonable solutions for both the low-temperature monoclinic and high-temperature rutile phases only if spin polarization is excluded from the calculations. We explore whether a satisfactory agreement with experiment can be achieved by tuning the fraction of Hartree Fock exchange (α) in the density functional. It is found that two branches of locally stable solutions exist for the rutile phase for 12.5%≤α≤20%. One is metallic and has the correct stability as compared to the monoclinic phase, the other is insulating with lower energy than the metallic branch. We discuss these observations based on the V 3d orbital occupations and conclude that α=10% is the best possible choice for spin-polarized VO2 calculations. © 2014 Elsevier B.V. All rights reserved.

  8. Organic spin clusters: macrocyclic-macrocyclic polyarylmethyl polyradicals with very high spin S = 5-13.

    Science.gov (United States)

    Rajca, Andrzej; Wongsriratanakul, Jirawat; Rajca, Suchada

    2004-06-02

    Synthesis and magnetic studies of a new class of organic spin clusters, possessing alternating connectivity of unequal spins, are described. Polyarylmethyl polyether precursors to the spin clusters, with linear and branched connectivity between calix[4]arene-based macrocycles, are prepared via modular, multistep syntheses. Their molecular connectivity and stereoisomerism are analyzed using NMR spectroscopy. The absolute masses (4-10 kDa) are determined by FABMS and GPC/MALS. Small angle neutron scattering (SANS) provides the radii of gyration of 1.2-1.8 nm. The corresponding polyradicals with 15, 22, and 36 triarylmethyls, which are prepared and studied as solutions in tetrahydrofuran-d(8), may be described as S' = 7/2, 1/2, 7/2 spin trimer (average S = 5-6), S' = 7/2, 1/2, 6/2, 1/2, 7/2 spin pentamer (average S = 7-9), and spin nonamer (average S = 11-13), respectively, as determined by SQUID magnetometry and numerical fits to linear combinations of the Brillouin functions. For spin trimer and pentamer, the quantitative magnetization data are fit to new percolation models, based upon random distributions of chemical defects and ferromagnetic vs antiferromagnetic couplings. The value of S = 13 is the highest for an organic molecule.

  9. High-spin research with HERA (High Energy-Resolution Array)

    Energy Technology Data Exchange (ETDEWEB)

    Diamond, R.M.

    1987-06-01

    The topic of this report is high spin research with the High Energy Resolution Array (HERA) at Lawrence Berkeley Laboratory. This is a 21 Ge detector system, the first with bismuth germanate (BGO) Compton suppression. The array is described briefly and some of the results obtained during the past year using this detector facility are discussed. Two types of studies are described: observation of superdeformation in the light Nd isotopes, and rotational damping at high spin and excitation energy in the continuum gamma ray spectrum.

  10. Spin States of Iron(III) in Highly Saddled Dodecaphenylporphyrin Complexes

    Energy Technology Data Exchange (ETDEWEB)

    Ohya, T., E-mail: ohyat@pharm.teikyo-u.ac.jp; Takeda, J.; Sato, M. [Teikyo University, Laboratory of Biophysics, Faculty of Pharmaceutical Sciences (Japan)

    2004-12-15

    Iron(III) complexes of highly saddled dodecaphenylporphyrin, Fe(DPP)X (X=Cl, Br or I) have been prepared and characterized by Moessbauer, UV-Vis and magnetic measurements. The Moessbauer spectra, recorded at temperatures from 5 to 300 K, contain two components A and B. Component A is attributed to iron(III) in a spin-admixed (S=3/2, 5/2) state. The UV-Vis spectra of solution samples of these complexes exhibit broad and red-shifted absorption bands. The effective magnetic moments derived from the molar magnetic susceptibilities measured by modified Gouy method at 298 K for X=Cl, Br and I are 5.52, 5.10 and 4.28 {mu}{sub B}, respectively.

  11. A novel high power X-band ferrite phase shifter.

    Science.gov (United States)

    Deng, G J; Huang, W H; Li, J W; Ba, T; Guo, L T; Jiang, Y

    2017-01-01

    A novel high power X-band ferrite phase shifter (PS) employing the structure of several waveguides connected in parallel is proposed. Each of the waveguides is a phase shift unit utilizing a dual-toroid structure. First, the phase shift unit is designed, manufactured, and tested. The results indicate that the power capacity reaches 115 kW. At this power, the maximum magnetic field strength of ferrite is 7.9 kA/m, beyond which the nonlinear effect of ferrite will occur. On this basis, the PS that consists of four units connected in parallel is designed. According to the threshold of ferrite, the power capacity of the PS can theoretically reach 430 kW. Limited by the maximum output power of the microwave source, the preliminary high-power test results demonstrate that the PS can operate properly at 270 kW. The PS exhibits an insertion loss of 0.82 dB and a maximum differential phase shift of approximately 300° at 9.3 GHz. The return loss of the PS is more than 16 dB from 9.0 to 9.5 GHz.

  12. High-resolution wide-band Fast Fourier Transform spectrometers

    CERN Document Server

    Klein, Bernd; Krämer, Ingo; Bell, Andreas; Meyer, Klaus; Güsten, Rolf

    2012-01-01

    We describe the performance of our latest generations of sensitive wide-band high-resolution digital Fast Fourier Transform Spectrometer (FFTS). Their design, optimized for a wide range of radio astronomical applications, is presented. Developed for operation with the GREAT far infrared heterodyne spectrometer on-board SOFIA, the eXtended bandwidth FFTS (XFFTS) offers a high instantaneous bandwidth of 2.5 GHz with 88.5 kHz spectral resolution and has been in routine operation during SOFIA's Basic Science since July 2011. We discuss the advanced field programmable gate array (FPGA) signal processing pipeline, with an optimized multi-tap polyphase filter bank algorithm that provides a nearly loss-less time-to-frequency data conversion with significantly reduced frequency scallop and fast sidelobe fall-off. Our digital spectrometers have been proven to be extremely reliable and robust, even under the harsh environmental conditions of an airborne observatory, with Allan-variance stability times of several 1000 se...

  13. High-pressure magic angle spinning nuclear magnetic resonance

    Science.gov (United States)

    Hoyt, David W.; Turcu, Romulus V. F.; Sears, Jesse A.; Rosso, Kevin M.; Burton, Sarah D.; Felmy, Andrew R.; Hu, Jian Zhi

    2011-10-01

    A high-pressure magic angle spinning (MAS) NMR capability, consisting of a reusable high-pressure MAS rotor, a high-pressure rotor loading/reaction chamber for in situ sealing and re-opening of the high-pressure MAS rotor, and a MAS probe with a localized RF coil for background signal suppression, is reported. The unusual technical challenges associated with development of a reusable high-pressure MAS rotor are addressed in part by modifying standard ceramics for the rotor sleeve by abrading the internal surface at both ends of the cylinder. In this way, not only is the advantage of ceramic cylinders for withstanding very high-pressure utilized, but also plastic bushings can be glued tightly in place so that other removable plastic sealing mechanisms/components and O-rings can be mounted to create the desired high-pressure seal. Using this strategy, sealed internal pressures exceeding 150 bars have been achieved and sustained under ambient external pressure with minimal loss of pressure for 72 h. As an application example, in situ13C MAS NMR studies of mineral carbonation reaction intermediates and final products of forsterite (Mg 2SiO 4) reacted with supercritical CO 2 and H 2O at 150 bar and 50 °C are reported, with relevance to geological sequestration of carbon dioxide.

  14. High-pressure magic angle spinning nuclear magnetic resonance

    Energy Technology Data Exchange (ETDEWEB)

    Hoyt, David W.; Turcu, Romulus V. F.; Sears, Jesse A.; Rosso, Kevin M.; Burton, Sarah D.; Felmy, Andrew R.; Hu, Jian Zhi

    2011-10-01

    A high-pressure magic angle spinning (MAS) NMR capability, consisting of a reusable high-pressure MAS rotor, a high-pressure rotor loading/reaction chamber for in situ sealing and re-opening of the high-pressure MAS rotor, and a MAS probe with a localized RF coil for background signal suppression, is reported. The unusual technical challenges associated with development of a reusable high-pressure MAS rotor are addressed in part by modifying standard ceramics for the rotor sleeve by abrading the internal surface at both ends of the cylinder. In this way, not only is the advantage of ceramic cylinders for withstanding very high-pressure utilized, but also plastic bushings can be glued tightly in place so that other removable plastic sealing mechanisms/components and O-rings can be mounted to create the desired high-pressure seal. Using this strategy, sealed internal pressures exceeding 150 bars have been achieved and sustained under ambient external pressure with minimal loss of pressure for 72 h. Finally, as an application example, in situ13C MAS NMR studies of mineral carbonation reaction intermediates and final products of forsterite (Mg2SiO4) reacted with supercritical CO2 and H2O at 150 bar and 50 °C are reported, with relevance to geological sequestration of carbon dioxide.

  15. Route toward high-speed nano-magnonics provided by pure spin currents

    Science.gov (United States)

    Divinskiy, B.; Demidov, V. E.; Demokritov, S. O.; Rinkevich, A. B.; Urazhdin, S.

    2016-12-01

    We study experimentally the possibility to utilize pulses of pure spin current, produced via the nonlocal spin injection mechanism, to generate short packets of spin waves propagating in nanoscale magnetic waveguides. Spatially and time-resolved micro-focus Brillouin light scattering spectroscopy measurements demonstrate that the excitation by spin current results in extremely fast transient response, enabling efficient generation of short spin-wave packets with duration down to a few nanoseconds. The proposed method opens a route for the implementation of high-speed magnonic systems for transmission and processing of information on the nanoscale.

  16. Shear jamming in highly strained granular system without shear banding

    Science.gov (United States)

    Zhao, Yiqiu; Barés, Jonathan; Zheng, Hu; Behringer, Robert

    2016-11-01

    Bi et al. have shown that, if sheared, a granular material can jam even if its packing fraction (ϕ) is lower than the critical isotropic jamming point ϕJ. They have introduced a new critical packing fraction value ϕS such that for ϕSjams if sheared. Nevertheless, the value of ϕS as a function of the shear profile or the strain necessary to observe jamming remain poorly understood because of the experimental complexity to access high strain without shear band. We present a novel 2D periodic shear apparatus made of 21 independent, aligned and mirrored glass rings. Each ring can be moved independently which permits us to impose any desired shear profile. The circular geometry allows access to any strain value. The forces between grains are measured using reflective photoelasticity. By performing different shear profiles for different packing fractions we explored the details of jamming diagram including the location of the yield surface. This work is supported by NSF No.DMR1206351, NASA No.NNX15AD38G and W. M. Keck Foundation.

  17. Reduction of collectivity at very high spins in 134Nd: Expanding the projected-shell-model basis up to 10-quasiparticle states

    Science.gov (United States)

    Wang, Long-Jun; Sun, Yang; Mizusaki, Takahiro; Oi, Makito; Ghorui, Surja K.

    2016-03-01

    Background: The recently started physics campaign with the new generation of γ -ray spectrometers, "GRETINA" and "AGATA," will possibly produce many high-quality γ rays from very fast-rotating nuclei. Microscopic models are needed to understand these states. Purpose: It is a theoretical challenge to describe high-spin states in a shell-model framework by the concept of configuration mixing. To meet the current needs, one should overcome the present limitations and vigorously extend the quasiparticle (qp) basis of the projected shell model (PSM). Method: With the help of the recently proposed Pfaffian formulas, we apply the new algorithm and develop a new PSM code that extends the configuration space to include up to 10-qp states. The much-enlarged multi-qp space enables us to investigate the evolutional properties at very high spins in fast-rotating nuclei. Results: We take 134Nd as an example to demonstrate that the known experimental yrast and the several negative-parity side bands in this nucleus could be well described by the calculation. The variations in moment of inertia with spin are reproduced and explained in terms of successive band crossings among the 2-qp, 4-qp, 6-qp, 8-qp, and 10-qp states. Moreover, the electric quadrupole transitions in these bands are studied. Conclusions: A pronounced decrease in the high-spin B (E 2 ) of 134Nd is predicted, which suggests reduction of collectivity at very high spins because of increased level density and complex band mixing. The possibility for a potential application of the present development in the study of highly excited states in warm nuclei is mentioned.

  18. TOPICAL REVIEW: Highly spin-polarized materials and devices for spintronics

    Directory of Open Access Journals (Sweden)

    Koichiro Inomata et al.

    2008-01-01

    Full Text Available The performance of spintronics depends on the spin polarization of the current. In this study half-metallic Co-based full-Heusler alloys and a spin filtering device (SFD using a ferromagnetic barrier have been investigated as highly spin-polarized current sources. The multilayers were prepared by magnetron sputtering in an ultrahigh vacuum and microfabricated using photolithography and Ar ion etching. We investigated two systems of Co-based full-Heusler alloys, Co2Cr1 ? xFexAl (CCFA(x and Co2FeSi1 ? xAlx (CFSA(x and revealed the structure and magnetic and transport properties. We demonstrated giant tunnel magnetoresistance (TMR of up to 220% at room temperature and 390% at 5 K for the magnetic tunnel junctions (MTJs using Co2FeSi0.5Al0.5 (CFSA(0.5 Heusler alloy electrodes. The 390% TMR corresponds to 0.81 spin polarization for CFSA(0.5 at 5 K. We also investigated the crystalline structure and local structure around Co atoms by x-ray diffraction (XRD and nuclear magnetic resonance (NMR analyses, respectively, for CFSA films sputtered on a Cr-buffered MgO (001 substrate followed by post-annealing at various temperatures in an ultrahigh vacuum. The disordered structures in CFSA films were clarified by NMR measurements and the relationship between TMR and the disordered structure was discussed. We clarified that the TMR of the MTJs with CFSA(0.5 electrodes depends on the structure, and is significantly higher for L21 than B2 in the crystalline structure. The second part of this paper is devoted to a SFD using a ferromagnetic barrier. The Co ferrite is investigated as a ferromagnetic barrier because of its high Curie temperature and high resistivity. We demonstrate the strong spin filtering effect through an ultrathin insulating ferrimagnetic Co-ferrite barrier at a low temperature. The barrier was prepared by the surface plasma oxidization of a CoFe2 film deposited on a MgO (001 single crystal substrate, wherein the spinel structure of CoFe2O4 (CFO

  19. STUDY OF HIGH-SPIN STATES IN THE NUCLEUS EU-149

    NARCIS (Netherlands)

    BACELAR, JC; JONGMAN, [No Value; NOORMAN, RF; DEVOIGT, MJA; NYBERG, J; SLETTEN, G; BERGSTROM, M; RYDE, H

    1994-01-01

    In-beam studies of high-spin states in Eu-149 are reported. The level scheme extends up to an excitation energy of 7.1 MeV and a spin of 55/2HBAR. This nucleus is weakly deformed and most of the high-spin structure is interpreted through its multi-particle-hole nature. Octupole-phonon vibrations cou

  20. High-spin states in boson models with applications to actinide nuclei

    CERN Document Server

    Kuyucak, S

    1995-01-01

    We use the 1/N expansion formalism in a systematic study of high-spin states in the sd and sdg boson models with emphasis on spin dependence of moment of inertia and E2 transitions. The results are applied to the high-spin states in the actinide nuclei ^{232}Th, ^{234-238}U, where the need for g bosons is especially acute but until now, no realistic calculation existed. We find that the d-boson energy plays a crucial role in description of the high-spin data.

  1. Complete protocol for slow-spinning high-resolution magic-angle spinning NMR analysis of fragile tissues.

    Science.gov (United States)

    André, Marion; Dumez, Jean-Nicolas; Rezig, Lamya; Shintu, Laetitia; Piotto, Martial; Caldarelli, Stefano

    2014-11-04

    High-resolution magic-angle spinning (HR-MAS) nuclear magnetic resonance (NMR) is an essential tool to characterize a variety of semisolid systems, including biological tissues, with virtually no sample preparation. The "non-destructive" nature of NMR is typically compromised, however, by the extreme centrifugal forces experienced under conventional HR-MAS frequencies of several kilohertz. These features limit the usefulness of current HR-MAS approaches for fragile samples. Here, we introduce a full protocol for acquiring high-quality HR-MAS NMR spectra of biological tissues at low spinning rates (down to a few hundred hertz). The protocol first consists of a carefully designed sample preparation, which yields spectra without significant spinning sidebands at low spinning frequency for several types of sample holders, including the standard disposable inserts classically used in HR-MAS NMR-based metabolomics. Suppression of broad spectral features is then achieved using a modified version of the recently introduced PROJECT experiment with added water suppression and rotor synchronization, which deposits limited power in the sample and which can be suitably rotor-synchronized at low spinning rates. The performance of the slow HR-MAS NMR procedure is demonstrated on conventional (liver tissue) and very delicate (fish eggs) samples, for which the slow-spinning conditions are shown to preserve the structural integrity and to minimize intercompartmental leaks of metabolites. Taken together, these results expand the applicability and reliability of HR-MAS NMR spectroscopy. These results have been obtained at 400 and 600 MHz and suggest that high-quality slow HR-MAS spectra can be expected at higher magnetic fields using the described protocol.

  2. An idiogram on pachytene bivalents with high resolution multiple bands of zebrafish (Danio rerio)

    Institute of Scientific and Technical Information of China (English)

    易梅生; 余其兴; 黄琳

    2002-01-01

    Well spread pachytene bivalents with high-resolution multiple bands of zebrafish were obtained after the testes were treated with alkaline hypotonic solution and high chloroform fixative solution. This might be the pattern with the largest number of multiple bands obtained from fish chromosomes so far published. Both the number and character of the bands in each bivalent were stable. According to the principles of ISCN (1978) and ISCN (1981), an idiogram of 599 bands was set up, and the detailed description of the landmark system and the band positions were given.

  3. Small sized high-gain PHEMT high-power amplifiers for X-band applications

    NARCIS (Netherlands)

    Hek, A.P. de; Hunneman, P.A.H.

    2000-01-01

    The development of two small sized broadband X-band high-power amplifiers is discussed. The amplifiers are realised with the help of the pseudomorphic HEMT technology of the Fraunhofer Institute for Applied Solid State Physics (FhG-IAF). With the help of this technology the feasibility of

  4. Small sized high-gain PHEMT high-power amplifiers for X-band applications

    NARCIS (Netherlands)

    Hek, A.P. de; Hunneman, P.A.H.

    2000-01-01

    The development of two small sized broadband X-band high-power amplifiers is discussed. The amplifiers are realised with the help of the pseudomorphic HEMT technology of the Fraunhofer Institute for Applied Solid State Physics (FhG-IAF). With the help of this technology the feasibility of integratin

  5. The Spin and Flavour Dependence of High-Energy Photoabsorption

    CERN Document Server

    Bass, S D

    1999-01-01

    We review the present data on high-energy, spin-dependent photoabsorption. We find a strong isotriplet term in $(\\sigma_A - \\sigma_P)$ which persists from $Q^2 \\sim 0.25$GeV$^2$ to high $Q^2$ polarised deep inelastic scattering. For $Q^2 \\sim 4$GeV$^2$ and $x$ between 0.01 and 0.12 the isotriplet part of $g_1$ behaves as $g_1^{(p-n)} \\sim x^{-{1 \\over 2}}$, in contrast to soft Regge theory which predicts that $g_1^{(p-n)}$ should converge as $x \\to 0$. The isotriplet, polarised structure function $2x g_1^{(p-n)}$ is significantly greater than the isotriplet, unpolarised structure function $F_2^{(p-n)}$ in this kinematic region. We analyse the low $Q^2$ photoabsorption data from E-143 and SMC and use this data to estimate the high-energy Regge contribution to the Drell-Hearn-Gerasimov sum-rule.

  6. Equilibrium of low- and high-spin states of Ni(II) complexes controlled by the donor ability of the bidentate ligands.

    Science.gov (United States)

    Ohtsu, Hideki; Tanaka, Koji

    2004-05-03

    Low-spin nickel(II) complexes containing bidentate ligands with modulated nitrogen donor ability, Py(Bz)2 or MePy(Bz)2 (Py(Bz)2 = N,N-bis(benzyl)-N-[(2-pyridyl)methyl]amine, MePy(Bz)2 = N,N-bis(benzyl)-N-[(6-methyl-2-pyridyl)methyl]amine), and a beta-diketonate derivative, tBuacacH (tBuacacH = 2,2,6,6-tetramethyl-3,5-heptanedione), represented as [Ni(Py(Bz)2)(tBuacac)](PF6) (1) and [Ni(MePy(Bz)2)(tBuacac)](PF6) (2) have been synthesized. In addition, the corresponding high-spin nickel(II) complexes having a nitrate ion, [Ni(Py(Bz)2)(tBuacac)(NO3)] (3) and [Ni(MePy(Bz)2)(tBuacac)(NO3)] (4), have also been synthesized for comparison. Complexes 1 and 2 have tetracoordinate low-spin square-planar structures, whereas the coordination environment of the nickel ion in 4 is a hexacoordinate high-spin octahedral geometry. The absorption spectra of low-spin complexes 1 and 2 in a noncoordinating solvent, dichloromethane (CH2Cl2), display the characteristic absorption bands at 500 and 540 nm, respectively. On the other hand, the spectra of a CH2Cl2 solution of high-spin complexes 3 and 4 exhibit the absorption bands centered at 610 and 620 nm, respectively. The absorption spectra of 1 and 2 in N,N-dimethylformamide (DMF), being a coordinating solvent, are quite different from those in CH2Cl2, which are nearly the same as those of 3 and 4 in CH2Cl2. This result indicates that the structures of 1 and 2 are converted from a low-spin square-planar to a high-spin octahedral configuration by the coordination of two DMF molecules to the nickel ion. Moreover, complex 1 shows thermochromic behavior resulting from the equilibrium between low-spin square-planar and high-spin octahedral structures in acetone, while complex 2 exists only as a high-spin octahedral configuration in acetone at any temperature. Such drastic differences in the binding constants and thermochromic properties can be ascribed to the enhancement of the acidity of the nickel ion of 2 by the steric effect of the o

  7. Electrically detected electron spin resonance in a high-mobility silicon quantum well.

    Science.gov (United States)

    Matsunami, Junya; Ooya, Mitsuaki; Okamoto, Tohru

    2006-08-11

    The resistivity change due to electron spin resonance (ESR) absorption is investigated in a high-mobility two-dimensional electron system formed in a Si/SiGe heterostructure. Results for a specific Landau level configuration demonstrate that the primary cause of the ESR signal is a reduction of the spin polarization, not the effect of electron heating. The longitudinal spin relaxation time T1 is obtained to be of the order of 1 ms in an in-plane magnetic field of 3.55 T. The suppression of the effect of the Rashba fields due to high-frequency spin precession explains the very long T1.

  8. Interplay between spin polarization and color superconductivity in high density quark matter

    DEFF Research Database (Denmark)

    Tsue, Yasuhiko; da Providência, João; Providência, Constança;

    2013-01-01

    Here, it is suggested that a four-point interaction of the tensor type may lead to spin polarization in quark matter at high density. It is found that the two-flavor superconducting phase and the spin polarized phase correspond to distinct local minima of a certain generalized thermodynamical...... potential. It follows that a transition from one to the other phase occurs, passing through true minima with both a spin polarization and a color superconducting gap. It is shown that the quark spin polarized phase is realized at rather high density, while the two-flavor color superconducting phase...

  9. Spin Hall effects in mesoscopic Pt films with high resistivity

    Science.gov (United States)

    Qin, Chuan; Luo, Yongming; Zhou, Chao; Cai, Yunjiao; Jia, Mengwen; Chen, Shuhan; Wu, Yizheng; Ji, Yi

    2016-10-01

    The energy efficiency of the spin Hall effects (SHE) can be enhanced if the electrical conductivity is decreased without sacrificing the spin Hall conductivity. The resistivity of Pt films can be increased to 150-300 µΩ · cm by mesoscopic lateral confinement, thereby decreasing the conductivity. The SHE and inverse spin Hall effects (ISHE) in these mesoscopic Pt films are explored at 10 K by using the nonlocal spin injection/detection method. All relevant physical quantities are determined in situ on the same substrate, and a quantitative approach is developed to characterize all processes effectively. Extensive measurements with various Pt thickness values reveal an upper limit for the Pt spin diffusion length: {λ\\text{pt}}   ⩽  0.8 nm. The average product of {λ\\text{pt}} and the Pt spin Hall angle {α\\text{H}} is substantial: {α\\text{H}}{λ\\text{pt}}   =  (0.142  ±  0.040) nm for 4 nm thick Pt, though a gradual decrease is observed at larger Pt thickness. The results suggest enhanced spin Hall effects in resistive mesoscopic Pt films.

  10. An experimental test of nuclear models at the N=Z line in the A{approx}70 region[High spin states

    Energy Technology Data Exchange (ETDEWEB)

    Kelsall, Nigel S

    2002-07-01

    Two experiments were performed to populate high-spin states in the N = Z nuclei {sup 70}Br and {sup 72}Kr and the N = Z + 1 nucleus {sup 73}Kr. A spectroscopanalysis has allowed high-spin states in {sup 70}Br to be experimentally observed for the first time in the present work. The previously known structure of {sup 72}Kr has been greatly extended and a second possible candidate for the continuation of the yrast band at high-spin has been observed. All three of the previously known rotational bands in {sup 73}Kr have been revised and greatly extended. The rotational frequency of the first band-crossing in {sup 72}Kr has been shown to be delayed with respect to its heavier neighbouring even-even isotopes. This delay is believed to be a spectroscopic signature of the presence of neutron-proton (np) pairing correlations. Exact deformed cranked shell model calculations which explicitly include both isovector (T = 1) and isoscalar (T = 0) np pairing correlations suggest that this observed delay in the crossing frequency could be caused by the presence of both T = 0 and T = 1 np pairing correlations. The rotational bands in {sup 73}Kr have been compared to extended Total Routhian Surface, Cranked Nilsson-Strutinsky and Cranked Relativistic Mean Field calculations. This comparison has shown that the extended TRS calculations may lack some important physics which is required for an accurate description of N {approx} Z nuclei. Neutron-proton pairing correlations seem to be the most likely candidate. In addition, the calculations predict an unusual band-crossing in the negative parity bands which may suggest the presence of T = 0 np pairing correlations. CNS calculations have been used to describe the high-spin rotational band which is believed to be built upon the 9{sup +} isomer in {sup 70}Br with reasonable success. The presence of T = 0 pairs at high-spin in this band is suggested by a mixing between the [2,2] and [3,3] configurations which would represent the scattering

  11. Six-band k•p calculation of spin-dependent interband tunneling in strained broken-gap heterostructures under a quantizing magnetic field

    Science.gov (United States)

    Zakharova, A.; Nilsson, K.; Chao, K. A.; Yen, S. T.

    2005-09-01

    We investigate spin-dependent interband magnetotunneling processes in strained broken-gap resonant tunneling structures made from InAs, AlSb, and GaSb, which are promising materials for quantum devices. InAs/AlSb/GaSb/InAs/AlSb/GaSb double-barrier structures grown on both InAs and GaSb are considered. Transmission coefficients for interband tunneling processes from individual eigenstates in the InAs emitter as well as current-voltage characteristics were calculated using a six-band k•p model and the scattering matrix method. We predict that due to lattice-mismatch induced strain, the interband tunneling current density for the structure grown on InAs can be one or two orders of magnitude less than that for the structure grown on GaSb. Furthermore, as a consequence of interband magnetotunneling, structures grown on different substrates yield different spin polarization of the tunneling current. It is obtained that the current spin polarization can be greater than 90%. These resonant tunneling structures can be used as spin filters in the rapidly growing field of spintronics.

  12. Hosting of surface states in spin-orbit induced projected bulk band gaps of W(1 1 0) and Ir(1 1 1)

    Science.gov (United States)

    Elmers, H. J.; Kutnyakhov, D.; Chernov, S. V.; Medjanik, K.; Fedchenko, O.; Zaporozhchenko-Zymakova, A.; Ellguth, M.; Tusche, C.; Viefhaus, J.; Schönhense, G.

    2017-06-01

    Spin-momentum locking of surface states has attracted great interest in recent years due to envisioned technological applications in the field of spintronics. Normal metal surfaces like W(1 1 0) and Ir(1 1 1) show surface states with energy dispersions and spin-polarization textures, which are reminiscent of topologically non-trivial surface states. In order to understand this phenomenon the connection of bulk and surface states has to be explored. Using time-of-flight momentum microscopy with soft x-ray excitation, we present a comprehensive analysis of the bulk bands of W and Ir. Surface states are determined by the same method with photon excitation in the vacuum ultraviolet region. The superposition of both spectral densities reveals the hosting of surface states within the gap structure of bulk bands projected on the surface Brillouin zone. Quantitative differences in the extension of experimental and theoretical local band gaps indicate an underestimation of electron correlation effects in theory.

  13. Spin-offs of high energy physics to society

    CERN Document Server

    Amaldi, Ugo

    2000-01-01

    Scientists are more and more frequently asked about the spin-offs of fundamental research. To answer effectively, it is important to organise the multiple aspects of knowledge and technology transfer in a coherent scheme. In this paper the spin-offs of particle physics to other fields of science and to industries are grouped in four streams: usable knowledge, people, methods and technologies. After treating these four items, with examples and suggestions of ways to improve the quality and quantity of the spin-offs, the pathways through which the results and the techniques of fundamental science percolate to society are discussed. (33 refs).

  14. Random Matrix Theory and Its Application to Decay out of Superdeformed Band

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    <正>The study of superdeformed (SD) bands is one of the most active fields of nuclear structure studies at high spin. The SD bands have been observed in many mass regions around A=20, 40, 80, 130, 150, 165,

  15. Toroidal high-spin isomers in light nuclei with N not equal to Z

    CERN Document Server

    Staszczak, Andrzej

    2014-01-01

    The combined considerations of both the bulk liquid-drop-type behavior and the quantized aligned rotation with cranked Skyrme-Hartree-Fock approach revealed previously that even-even, N=Z, toroidal high-spin isomeric states have general occurrences for light nuclei with A between 28 and 52. We find that in this mass region there are in addition N not equal to Z toroidal high-spin isomers when the single-particle shells for neutrons and protons occur at the same cranked frequency $\\hbar \\omega$. Examples of N not equal to Z toroidal high-spin isomers, $^{36}_{16}$S$_{20}$($I$=74$\\hbar$) and $^{40}_{18}$Ar$_{22}$($I$=80,102$\\hbar$), are located and examined. The systematic properties of these N not equal to Z toroidal high-spin isomers fall into the same regular (muti-particle)-(muti-hole) patterns as other N=Z toroidal high-spin isomers.

  16. Hyperfine rather than spin splittings dominate the fine structure of the B {sup 4}Σ{sup −}–X {sup 4}Σ{sup −} bands of AlC

    Energy Technology Data Exchange (ETDEWEB)

    Clouthier, Dennis J., E-mail: dclaser@uky.edu; Kalume, Aimable [Department of Chemistry, University of Kentucky, Lexington, Kentucky 40506-0055 (United States)

    2016-01-21

    Laser-induced fluorescence and wavelength resolved emission spectra of the B {sup 4}Σ{sup −}–X {sup 4}Σ{sup −} band system of the gas phase cold aluminum carbide free radical have been obtained using the pulsed discharge jet technique. The radical was produced by electron bombardment of a precursor mixture of trimethylaluminum in high pressure argon. High resolution spectra show that each rotational line of the 0-0 and 1-1 bands of AlC is split into at least three components, with very similar splittings and intensities in both the P- and R-branches. The observed structure was reproduced by assuming b{sub βS} magnetic hyperfine coupling in the excited state, due to a substantial Fermi contact interaction of the unpaired electron in the aluminum 3s orbital. Rotational analysis has yielded ground and excited state equilibrium bond lengths in good agreement with the literature and our own ab initio values. Small discrepancies in the calculated intensities of the hyperfine lines suggest that the upper state spin-spin constant λ′ is of the order of ≈0.025–0.030 cm{sup −1}.

  17. High temperature spin dynamics in linear magnetic chains, molecular rings, and segments by nuclear magnetic resonance

    Energy Technology Data Exchange (ETDEWEB)

    Adelnia, Fatemeh; Lascialfari, Alessandro [Dipartimento di Fisica, Università degli Studi di Milano and INSTM, Milano (Italy); Dipartimento di Fisica, Università degli Studi di Pavia and INSTM, Pavia (Italy); Mariani, Manuel [Dipartimento di Fisica e Astronomia, Università di Bologna, Bologna (Italy); Ammannato, Luca; Caneschi, Andrea; Rovai, Donella [Dipartimento di Chimica, Università degli Studi di Firenze and INSTM, Firenze (Italy); Winpenny, Richard; Timco, Grigore [School of Chemistry, The University of Manchester, Manchester (United Kingdom); Corti, Maurizio, E-mail: maurizio.corti@unipv.it; Borsa, Ferdinando [Dipartimento di Fisica, Università degli Studi di Pavia and INSTM, Pavia (Italy)

    2015-05-07

    We present the room temperature proton nuclear magnetic resonance (NMR) nuclear spin-lattice relaxation rate (NSLR) results in two 1D spin chains: the Heisenberg antiferromagnetic (AFM) Eu(hfac){sub 3}NITEt and the magnetically frustrated Gd(hfac){sub 3}NITEt. The NSLR as a function of external magnetic field can be interpreted very well in terms of high temperature spin dynamics dominated by a long time persistence of the decay of the two-spin correlation function due to the conservation of the total spin value for isotropic Heisenberg chains. The high temperature spin dynamics are also investigated in Heisenberg AFM molecular rings. In both Cr{sub 8} closed ring and in Cr{sub 7}Cd and Cr{sub 8}Zn open rings, i.e., model systems for a finite spin segment, an enhancement of the low frequency spectral density is found consistent with spin diffusion but the high cut-off frequency due to intermolecular anisotropic interactions prevents a detailed analysis of the spin diffusion regime.

  18. Frequency tuning of polarization oscillations: Toward high-speed spin-lasers

    Energy Technology Data Exchange (ETDEWEB)

    Lindemann, Markus, E-mail: markus.lindemann@rub.de; Gerhardt, Nils C.; Hofmann, Martin R. [Photonics and Terahertz Technology, Ruhr-University Bochum, 44780 Bochum (Germany); Pusch, Tobias; Michalzik, Rainer [Institute of Optoelectronics, Ulm University, 89081 Ulm (Germany)

    2016-01-25

    Spin-controlled vertical-cavity surface-emitting lasers (spin-VCSELs) offer a high potential to overcome several limitations of conventional purely charged-based laser devices. Presumably, the highest potential of spin-VCSELs lies in their ultrafast spin and polarization dynamics, which can be significantly faster than the intensity dynamics in conventional devices. Here, we experimentally demonstrate polarization oscillations in spin-VCSELs with frequencies up to 44 GHz. The results show that the oscillation frequency mainly depends on the cavity birefringence, which can be tuned by applying mechanical strain to the VCSEL structure. A tuning range of about 34 GHz is demonstrated. By measuring the polarization oscillation frequency and the birefringence governed mode splitting as a function of the applied strain simultaneously, we are able to investigate the correlation between birefringence and polarization oscillations in detail. The experimental findings are compared to numerical calculations based on the spin-flip model.

  19. High-resolution NMR of anisotropic samples with spinning away from the magic angle

    Energy Technology Data Exchange (ETDEWEB)

    Sakellariou, Dimitris; Meriles, Carlos A.; Martin, Rachel W.; Pines, Alexander

    2003-03-31

    High-resolution NMR of samples in the solid state is typically performed under mechanical sample spinning around an axis that makes an angle, called the magic angle, of 54.7 degrees with the static magnetic field. There are many cases in which geometrical and engineering constraints prevent spinning at this specific angle. Implementations of in-situ and ex-situ magic angle field spinning might be extremely demanding because of the power requirements or an inconvenient sample size or geometry. Here we present a methodology based on switched angle spinning between two angles, none of which is the magic angle, which provide both isotropic and anisotropic information. Using this method, named Projected Magic Angle Spinning, we were able to obtain resolved isotropic chemical shifts in spinning samples where the broadening is mostly inhomogeneous.

  20. A new high-spin isomer in {sup 195}Bi

    Energy Technology Data Exchange (ETDEWEB)

    Roy, T.; Mukherjee, G.; Rana, T.K.; Bhattacharya, Soumik; Asgar, Md.A.; Bhattacharya, C.; Bhattacharya, S.; Bhattacharyya, S.; Pai, H. [Variable Energy Cyclotron Centre, Kolkata (India); Madhavan, N.; Bala, I.; Gehlot, J.; Gurjar, R.K.; Jhingan, A.; Kumar, R.; Muralithar, S.; Nath, S.; Singh, R.P.; Varughese, T. [Inter University Acclerator Centre, New Delhi (India); Basu, K.; Bhattacharjee, S.S.; Ghugre, S.S.; Raut, R.; Sinha, A.K. [UGC-DAE-CSR Kolkata Centre, Kolkata (India); Palit, R. [Tata Institute of Fundamental Research, Department of Nuclear and Atomic Physics, Mumbai (India)

    2015-11-15

    A new high-spin isomer has been identified in {sup 195}Bi at the focal plane of the HYbrid Recoil mass Analyser (HYRA) used in the gas-filled mode. The fusion evaporation reactions {sup 169}Tm ({sup 30}Si, x n) {sup 193,} {sup 195}Bi were used with the beam energies on targets of 168 and 146MeV for 6n and 4n channels, respectively. The evaporation residues, separated from the fission fragments, and their decays were detected at the focal plane of HYRA using MWPC, Si-Pad and clover HPGe detectors. The half-life of the new isomer in {sup 195}Bi has been measured to be 1.6(1) μs. The configuration of the new isomer has been proposed and compared with the other isomers in this region. The Total Routhian Surface (TRS) calculations for the three-quasiparticle configurations corresponding to the new isomer suggest an oblate deformation for this isomeric state. The same calculations for different configurations in {sup 195}Bi and for the even-even {sup 194}Pb core indicate that the proton i{sub 13/2} orbital has a large shape driving effect towards oblate shape in these nuclei. (orig.)

  1. Observations of high spin states in {sup 179}Au

    Energy Technology Data Exchange (ETDEWEB)

    Carpenter, M.P.; Ahmad, I.; Blumenthal, D.J. [and others

    1995-08-01

    As part of a current study on the properties of the {pi} i{sub 13/2} intruder state in the A = 175-190 region, we conducted an experiment at ATLAS to observe high spin states in {sup 179}Au utilizing the reaction {sup 144}Sm({sup 40}Ar,p4n) at beam energies of 207 MeV and 215 MeV. To aid in the identification of {sup 179}Au, and to filter out the large amount of events from fission by-products, the Fragment Mass Analyzer was utilized in conjunction with ten Compton-suppression germanium detectors. In total, 11 x 10{sup 6} {gamma}-{gamma} and 4 x 10{sup 5} {gamma}-recoil events were collected. By comparing {gamma}-rays in coincidence with an A = 179 recoil mass gate and {gamma}-rays in coincidence with Au K{alpha} and K{beta} X-rays, ten {gamma}-rays were identified as belonging to {sup 179}Au. Based on {gamma}-ray coincidence relationships and on comparisons with neighboring odd-A Au nuclei, we constructed a tentative level scheme and assigned a rotational-like sequence to the {pi} i{sub 13/2} proton configuration.

  2. Spin-orbit contributions in high-spin nitrenes/carbenes: a hybrid CASSCF/MRMP2 study of zero-field splitting tensors.

    Science.gov (United States)

    Sugisaki, Kenji; Toyota, Kazuo; Sato, Kazunobu; Shiomi, Daisuke; Kitagawa, Masahiro; Takui, Takeji

    2010-10-04

    Zero-field splitting (ZFS) tensors (D tensors) of organic high-spin oligonitrenes/oligocarbenes up to spin-septet are quantitatively determined on the basis of quantum chemical calculations. The spin-orbit contributions, D(SO) tensors are calculated in terms of a hybrid CASSCF/MRMP2 approach, which was recently proposed by us. The spin-spin counterparts, D(SS) tensors are computed based on McWeeny-Mizuno's equation in conjunction with the RODFT spin densities. The present calculations show that more than 10% of ZFS arises from spin-orbit interactions in the high-spin nitrenes under study. Contributions of spin-bearing site-site interactions are estimated with the aid of a semi-empirical model for the D tensors and found to be ca. 5% of the D(SO) tensor. The analysis of intermediate states reveal that the largest contributions to the calculated D(SO) tensors are attributed to intra-site spin flip excitations and delocalized π and π* orbitals play an important role in the inter-site spin-orbit interactions.

  3. Resonantly pumped high power flat L-band erbium-doped superfluorescent fiber source.

    Science.gov (United States)

    Chen, Sheng-Ping; Liu, Ze-Jin; Li, Yi-Gang; Lu, Ke-Cheng; Zhou, Shou-Huan

    2008-01-07

    An all-single-mode-fiber L-band superfluorescent fiber source (SFS) with 1 W output power, 34.3 nm bandwidth (FWHM) and 54% optical conversion efficiency is constructed by seeding a high power erbium-doped fiber amplifier (EDFA) with a low power L-band ASE seed source to avoid parasitic lasing. The source is resonantly pumped by a high power C-band SFS peaked at 1545 nm.

  4. Optical-coupling nuclear spin maser under highly stabilized low static field

    Energy Technology Data Exchange (ETDEWEB)

    Yoshimi, A., E-mail: yoshimi@ribf.riken.jp [RIKEN Nishina Center (Japan); Inoue, T.; Uchida, M.; Hatakeyama, N.; Asahi, K. [Tokyo Institute of Technology, Department of Physics (Japan)

    2008-01-15

    A nuclear spin maser of a new type, that employs a feedback scheme based on optical nuclear spin detection, has been fabricated. The spin maser is operated at a low static field of 30 mG by using the optical detection method. The frequency stability and precision of the spin maser have been improved by a highly stabilized current source for the static magnetic field. An experimental setup to search for an electric dipole moment (EDM) in {sup 129}Xe atom is being developed.

  5. Ultra-broad band and dual-band highly efficient polarization conversion based on the three-layered chiral structure

    Science.gov (United States)

    Xu, Kai-kai; Xiao, Zhong-yin; Tang, Jing-yao; Liu, De-jun; Wang, Zi-hua

    2016-07-01

    In the paper, a novel three-layered chiral structure is proposed and investigated, which consists of a split-ring resonator sandwiched between two layers of sub-wavelength gratings. This designed structure can achieve simultaneously asymmetric transmission with an extremely broad bandwidth and high amplitude as well as multi-band 90° polarization rotator with very low dispersion. Numerical simulations adopted two kinds of softwares with different algorithms demonstrate that asymmetric parameter can reach a maximum of 0.99 and over than 0.8 from 4.6 to 16.8 GHz, which exhibit magnitude and bandwidth improvement over previous chiral metamaterials in microwave bands (S, C, X and Ku bands). Specifically, the reason of high amplitude is analyzed in detail based on the Fabry-perot like resonance. Subsequently, the highly efficient polarization conversion with very low dispersion between two orthogonal linearly polarized waves is also analyzed by the optical activity and ellipticity. Finally, the electric fields are also investigated and further demonstrate the correctness of the simulated and calculated results.

  6. Spin currents injected electrically and thermally from highly spin polarized Co{sub 2}MnSi

    Energy Technology Data Exchange (ETDEWEB)

    Pfeiffer, Alexander; Reeve, Robert M.; Kronenberg, Alexander; Jourdan, Martin; Kläui, Mathias, E-mail: klaeui@uni-mainz.de [Institut für Physik, Johannes Gutenberg-Universität Mainz, 55099 Mainz (Germany); Hu, Shaojie [Research Center for Quantum Nano-Spin Sciences, Kyushu University, 6-10-1 Hakozaki, Fukuoka 812-8581 (Japan); Kimura, Takashi [Research Center for Quantum Nano-Spin Sciences, Kyushu University, 6-10-1 Hakozaki, Fukuoka 812-8581 (Japan); Department of Physics, Kyushu University, 6-10-1 Hakozaki, Fukuoka 812-8581 (Japan)

    2015-08-24

    We demonstrate the injection and detection of electrically and thermally generated spin currents probed in Co{sub 2}MnSi/Cu lateral spin valves. Devices with different electrode separations are patterned to measure the non-local signal as a function of the electrode spacing and we determine a relatively high effective spin polarization α of Co{sub 2}MnSi to be 0.63 and the spin diffusion length of Cu to be 500 nm at room temperature. The electrically generated non-local signal is measured as a function of temperature and a maximum signal is observed for a temperature of 80 K. The thermally generated non-local signal is measured as a function of current density and temperature in a second harmonic measurement detection scheme. We find different temperature dependences for the electrically and thermally generated non-local signals, which allows us to conclude that the temperature dependence of the signals is not just dominated by the transport in the Cu wire, but there is a crucial contribution from the different generation mechanisms, which has been largely disregarded till date.

  7. Isolated Spin Qubits in SiC with a High-Fidelity Infrared Spin-to-Photon Interface

    Science.gov (United States)

    Christle, David J.; Klimov, Paul V.; de las Casas, Charles F.; Szász, Krisztián; Ivády, Viktor; Jokubavicius, Valdas; Ul Hassan, Jawad; Syväjärvi, Mikael; Koehl, William F.; Ohshima, Takeshi; Son, Nguyen T.; Janzén, Erik; Gali, Ádám; Awschalom, David D.

    2017-04-01

    The divacancies in SiC are a family of paramagnetic defects that show promise for quantum communication technologies due to their long-lived electron spin coherence and their optical addressability at near-telecom wavelengths. Nonetheless, a high-fidelity spin-photon interface, which is a crucial prerequisite for such technologies, has not yet been demonstrated. Here, we demonstrate that such an interface exists in isolated divacancies in epitaxial films of 3C-SiC and 4H-SiC. Our data show that divacancies in 4H-SiC have minimal undesirable spin mixing, and that the optical linewidths in our current sample are already similar to those of recent remote entanglement demonstrations in other systems. Moreover, we find that 3C-SiC divacancies have a millisecond Hahn-echo spin coherence time, which is among the longest measured in a naturally isotopic solid. The presence of defects with these properties in a commercial semiconductor that can be heteroepitaxially grown as a thin film on Si shows promise for future quantum networks based on SiC defects.

  8. Spiral spin state in high-temperature copper-oxide superconductors: Evidence from neutron scattering measurements

    DEFF Research Database (Denmark)

    Lindgård, Per-Anker

    2005-01-01

    An effective spiral spin phase ground state provides a new paradigm for the high-temperature superconducting cuprates. It accounts for the recent neutron scattering observations of spin excitations regarding both the energy dispersion and the intensities, including the "universal" rotation by 45...

  9. High-performance spinning device for DVD-based micromechanical signal transduction

    DEFF Research Database (Denmark)

    Hwu, En-Te; Chen, Ching-Hsiu; Bosco, Filippo

    2013-01-01

    Here we report a high-throughput spinning device for nanometric scale measurements of microstructures with instrumentation details and experimental results. The readout technology implemented in the designed disc-like device is based on a DVD data storage optical pick-up unit (OPU). With a spinning...

  10. Caring Climate, Empathy, and Student Social Behaviors in High School Band

    Science.gov (United States)

    Lalama, Susana M.

    2016-01-01

    The purpose of this study was to explore connections among perceived caring climate, empathy, and student social behaviors in high school bands. Nine high school band directors (N = 9 schools), along with their students (N = 203), completed an electronic questionnaire for variables of caring climate, cognitive empathy, affective empathy, social…

  11. High-power picosecond pulse delivery through hollow core photonic band gap fibers

    DEFF Research Database (Denmark)

    Michieletto, Mattia; Johansen, Mette Marie; Lyngsø, Jens Kristian;

    2015-01-01

    We demonstrated robust and bend insensitive fiber delivery of high power pulsed laser with diffraction limited beam quality for two different kind of hollow core photonic band gap fibers......We demonstrated robust and bend insensitive fiber delivery of high power pulsed laser with diffraction limited beam quality for two different kind of hollow core photonic band gap fibers...

  12. Differences in Myers-Briggs Personality Types among High School Band, Orchestra, and Choir Members

    Science.gov (United States)

    MacLellan, Christin Reardon

    2011-01-01

    The purpose of this study was to explore personality type differences among high school band, string orchestra, and choir students according to ensemble membership. Participants (N = 355) were high school students who had participated in their school's band, orchestra, or choir for 1 year or more. The author administered the Myers-Briggs Type…

  13. Low-cost high-efficient 10-Watt X-band high-power amplifier

    NARCIS (Netherlands)

    Bent, G. van der; Hek, A.P. de; Bessemoulin, A.; Vliet, F.E. van

    2009-01-01

    A high power X-band amplifier with an output power over 10 Watts and a Power Added Efficiency (PAE) in excess of 40 percent has been developed. The design was fabricated in a 0.25 μm pHEMT GaAs process (WIN Semiconductor PP25-01). The small die area in combination with a 6-inch wafer technology prov

  14. A density functional theory study of the zero-field splitting in high-spin nitrenes

    Science.gov (United States)

    Misochko, Eugenii Ya.; Korchagin, Denis V.; Bozhenko, Konstantin V.; Chapyshev, Sergei V.; Aldoshin, Sergei M.

    2010-08-01

    This work presents a detailed evaluation of the performance of density functional theory (DFT) for the prediction of zero-field splittings (ZFSs) in high-spin nitrenes. A number of well experimentally characterized triplet mononitrenes, quartet nitrenoradicals, quintet dinitrenes, and septet trinitrenes have been considered. Several DFT-based approaches for the prediction of ZFSs have been compared. It is shown that the unrestricted Kohn-Sham and the Pederson-Khanna approaches are the most successful for the estimation of the direct spin-spin (SS) interaction and the spin-orbit coupling (SOC) parts, respectively, to the final ZFS parameters. The most accurate theoretical predictions (within 10%) are achieved by using the PBE density functional in combination with the DZ, EPR-II, and TZV basis sets. For high-spin nitrenes constituted from light atoms, the contribution of the SOC part to ZFS parameters is quite small (7%-12%). By contrast, for chlorine-substituted septet trinitrenes, the contribution of the SOC part is small only to D value but, in the case of E value, it is as large as the SS part and has opposite sign. Due to this partial cancellation of two different contributions, SS and SOC, the resulting values of E in heavy molecules are almost two times smaller than those predicted by analysis of the widely used semiempirical one-center spin-spin interaction model. The decomposition of DSS into n-center (n =1-4) interactions shows that the major contribution to DSS results from the one-center spin-spin interactions. This fact indicates that the semiempirical SS interaction model accurately predicts the ZFS parameters for all types of high-spin nitrenes with total spin S =2 and 3, if their molecules are constructed from the first-row atoms.

  15. Spin fluctuations and high-temperature superconductivity in cuprates

    Science.gov (United States)

    Plakida, Nikolay M.

    2016-12-01

    To describe the cuprate superconductors, models of strongly correlated electronic systems, such as the Hubbard or t - J models, are commonly employed. To study these models, projected (Hubbard) operators have to be used. Due to the unconventional commutation relations for the Hubbard operators, a specific kinematical interaction of electrons with spin and charge fluctuations emerges. The interaction is induced by the intraband hopping with a coupling parameter of the order of the kinetic energy of electrons W which is much larger than the antiferromagnetic exchange interaction J induced by the interband hopping. This review presents a consistent microscopic theory of spin excitations and superconductivity for cuprates where these interactions are taken into account within the Hubbard operator technique. The low-energy spin excitations are considered for the t-J model, while the electronic properties are studied using the two-subband extended Hubbard model where the intersite Coulomb repulsion V and electron-phonon interaction are taken into account.

  16. Snakes and spin rotators for high energy accelerators

    Energy Technology Data Exchange (ETDEWEB)

    Lee, S.Y. (Indiana Univ., Bloomington, IN (USA). Dept. of Physics)

    1991-08-15

    A modification to the continuous family of snake and spin rotators, discovered by Steffen, is discussed. A compact snake configuration is found to have the advantages of requiring a smaller total integrated dipole magnet strength and a smaller transverse displacement for circulating particles. A split snake configuration has the advantage of allowing an entire experimental insertion region to be located between the two halves of the snake. Such configuration could serve as both a snake and a 90deg spin rotator for experiments requiring different helicity states. General properties of these snake configurations are discussed. (orig.).

  17. Problems and Progress in Covariant High Spin Description

    CERN Document Server

    Kirchbach, Mariana

    2016-01-01

    A universal description of particles with spins j greater or equal one , transforming in (j,0)+(0,j), is developed by means of representation specific second order differential wave equations without auxiliary conditions and in covariant bases such as Lorentz tensors for bosons, Lorentz-tensors with Dirac spinor components for fermions, or, within the basis of the more fundamental Weyl-Van-der-Waerden sl(2,C) spinor-tensors. At the root of the method, which is free from the pathologies suffered by the traditional approaches, are projectors constructed from the Casimir invariants of the spin-Lorentz group, and the group of translations in the Minkowski space time.

  18. Problems and Progress in Covariant High Spin Description

    Science.gov (United States)

    Kirchbach, Mariana; Banda Guzmán, Víctor Miguel

    2016-10-01

    A universal description of particles with spins j > 1, transforming in (j, 0) ⊕ (0, j), is developed by means of representation specific second order differential wave equations without auxiliary conditions and in covariant bases such as Lorentz tensors for bosons, Lorentz-tensors with Dirac spinor components for fermions, or, within the basis of the more fundamental Weyl- Van-der-Waerden sl(2,C) spinor-tensors. At the root of the method, which is free from the pathologies suffered by the traditional approaches, are projectors constructed from the Casimir invariants of the spin-Lorentz group, and the group of translations in the Minkowski space time.

  19. Observation of spin-polarized bands and domain-dependent Fermi arcs in polar Weyl semimetal MoT e2

    Science.gov (United States)

    Sakano, M.; Bahramy, M. S.; Tsuji, H.; Araya, I.; Ikeura, K.; Sakai, H.; Ishiwata, S.; Yaji, K.; Kuroda, K.; Harasawa, A.; Shin, S.; Ishizaka, K.

    2017-03-01

    We investigate the surface electronic structures of polar 1 T'-MoT e2 , the Weyl semimetal candidate realized through the nonpolar-polar structural phase transition, by utilizing the laser angle-resolved photoemission spectroscopy combined with first-principles calculations. Two kinds of domains with different surface band dispersions are observed from a single-crystalline sample. The spin-resolved measurements further reveal that the spin polarizations of the surface and the bulk-derived states show the different domain dependences, indicating the opposite bulk polarity. For both domains, some segmentlike band features resembling the Fermi arcs are clearly observed. The patterns of the arcs present the marked contrast between the two domains, respectively agreeing well with the slab calculation of (0 0 1) and (0 0 -1) surfaces. The present result strongly suggests that the Fermi arc connects the identical pair of Weyl nodes on one side of the polar crystal surface, whereas it connects between the different pairs of Weyl nodes on the other side.

  20. High-frequency manipulation of few-electron double quantum dots-toward spin qubits

    Science.gov (United States)

    Kodera, T.; van der Wiel, W. G.; Ono, K.; Sasaki, S.; Fujisawa, T.; Tarucha, S.

    2004-04-01

    We use a photon-assisted tunneling (PAT) technique to study the high-frequency response of one- and two-electron states in a semiconductor vertically coupled double-dot system. In particular, PAT associated with two-electron spin states in the spin-blockade regime is observed up to the absorption of 10 photons, indicating the preservation of long relaxation times and hence the robustness of our electron spin device under strong microwave irradiation. An alternative double-dot structure with greater flexibility in tuning the inter-dot coupling is presented and its transport characteristics are discussed. This structure is proposed for high-frequency control of two-electron spin states, as required for quantum computation schemes using electron spins in quantum dots.

  1. Fiber-wireless links supporting high-capacity W-band channels

    DEFF Research Database (Denmark)

    Vegas Olmos, Juan José; Tafur Monroy, Idelfonso

    2013-01-01

    , is seeding the need to use bands located at the millimeter-wave region (30-300 GHz), mainly because of its inherent broadband nature. In our lab, we have conducted extensive research on high-speed photonic-wireless links in the V-band (50-75GHz) and the W-band (75-110GHz). In this paper, we will present our...

  2. Theoretical studies of possible toroidal high-spin isomers in the light-mass region

    CERN Document Server

    Staszczak, Andrzej

    2015-01-01

    We review our theoretical knowledge of possible toroidal high-spin isomers in the light mass region in 28$\\le$$A$$\\le$52 obtained previously in cranked Skyrme-Hartree-Fock calculations. We report additional toroidal high-spin isomers in $^{56}$Ni with $I$=114$\\hbar$ and 140$\\hbar$, which follow the same (multi-particle)--(multi-hole) systematics as other toroidal high-spin isomers. We examine the production of these exotic nuclei by fusion of various projectiles on $^{20}$Ne or $^{28}$Si as an active target in time-projection-chamber (TCP) experiments.

  3. Research on Control System of Spindle Drive for High Speed Spinning Machine

    Institute of Scientific and Technical Information of China (English)

    魏建

    2001-01-01

    Through analyzing the principle of spindle drive of winding mechanism for high speed spinning machine,the article not only describes a kind of mode of spindle drive for take-up motion on the basis of control method of constant velocity winding, but also introduces the design technique of software and hardware for the control system of mechatronics of spindle drive mode for take- up motion on the basis of constant velocity winding for high speed spinning machine with single-chip microcomputer. The mathematical model to describe the spindle rotating speed is established. It is an important technology for high speed spinning machine and provides a feasible application way.

  4. Revisiting orbital-fluctuation-mediated superconductivity in LiFeAs: Nontrivial spin-orbit interaction effects on the band structure and superconducting gap function

    Science.gov (United States)

    Saito, Tetsuro; Yamakawa, Youichi; Onari, Seiichiro; Kontani, Hiroshi

    2015-10-01

    The precise gap structure in LiFeAs (Tc=18 K) given by ARPES studies offers significant information that helps us understand the pairing mechanism in iron-based superconductors. The most remarkable characteristic in the LiFeAs gap structure would be that "the largest gap emerges on the tiny hole-pockets around the Z point." This result has been naturally explained in terms of the orbital-fluctuation scenario [T. Saito et al., Phys. Rev. B 90, 035104 (2014)], 10.1103/PhysRevB.90.035104, whereas the opposite result is obtained by the spin-fluctuation scenario. In this paper, we study the gap structure in LiFeAs by taking the spin-orbit interaction (SOI) into account, motivated by the recent ARPES studies that revealed a significant SOI-induced modification of the Fermi surface topology. For this purpose, we construct two possible tight-binding models with finite SOI by referring the band structures given by different ARPES groups. In addition, we extend the gap equation for multiorbital systems with finite SOI, and calculate the gap functions by applying the orbital-spin fluctuation theory. On the basis of both SOI-induced band structures, the main characteristics of the gap structure in LiFeAs are naturally reproduced only in the presence of strong interorbital interactions between (dx z /y z-dx y) orbitals. Thus the experimental gap structure in LiFeAs is a strong evidence for the orbital-fluctuation pairing mechanism.

  5. MMIC for High-Efficiency Ka-BAnd GaN Power Amplifiers (2007043) Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This proposal addresses the need for high-efficiency, high-output power amplifiers operating in the Ka-band frequencies. For space communications, the power...

  6. Investigation of the high-spin rotational properties of the proton emitter $^{113}$Cs using a particle-number conserving method

    CERN Document Server

    Zhang, Zhen-Hua

    2016-01-01

    The recently observed two high-spin rotational bands in the proton emitter $^{113}$Cs are investigated using the cranked shell model with pairing correlations treated by a particle-number conserving method, in which the Pauli blocking effects are taken into account exactly. By using the configuration assignments of band 1 ($\\pi 3/2^+[422], \\alpha = -1/2$) and band 2 ($\\pi 1/2^+[420], \\alpha = 1/2$), the experimental moments of inertia and quasiparticle alignments can be well reproduced by the present calculations, which in turn strongly support these configuration assignments. Furthermore, by analyzing the occupation probability $n_\\mu$ of each cranked Nilsson level near the Fermi surface and the contribution of each orbital to the angular momentum alignments, the backbending mechanism of these two bands is also investigated.

  7. Nonadditivity in moments of inertia of high-K multiquasiparticle bands

    Institute of Scientific and Technical Information of China (English)

    ZHANG Zhen-Hua; WU Xi; LEI Yi-An; ZENG Jin-Yan

    2008-01-01

    The experimental high-K 2-and 3-quasiparticle bands of well deformed rare-earth nuclei are analyzed.It is found that there exists significant nonadditivity in moments of inertia(MOIs)for these bands.The microscopic mechanism of the rotatiohal bands is investigated by the particle number conserving(PNC)method in the frame of cranked shell model with pairing.in which the blocking effects are taken care of exactly.The experimental rotational frequency dependenEe of these bands is well reproduced in PNC calculations.The nonadditivity in MOIs originates from the destructive interference between Pauli blocking effects.

  8. Spin-polarized high-energy scattering of charged leptons on nucleons

    Energy Technology Data Exchange (ETDEWEB)

    Burkardt, Matthias; Nowak, Wolf-Dieter; MILLER, A.

    2009-01-01

    The proton is a composite object with spin one-half, understood to contain highly relativistic spin one-half quarks exchanging spin-one gluons, each possibly with significant orbital angular momenta. While their fundamental interactions are well described by Quantum ChromoDynamics (QCD), our standard theory of the strong interaction, nonperturbative calculations of the internal structure of the proton based directly on QCD are beginning to provide reliable results. Most of our present knowledge of the structure of the proton is based on experimental measurements interpreted within the rich framework of QCD. An area presently attracting intense interest, both experimental and theoretical, is the relationship between the spin of the proton and the spins and orbital angular momenta of its constituents. While remarkable progress has been made, especially in the last decade, the discovery and investigation of new concepts have revealed that much more remains to be learned. This progress i

  9. Generating highly polarized nuclear spins in solution using dynamic nuclear polarization

    DEFF Research Database (Denmark)

    Wolber, J.; Ellner, F.; Fridlund, B.;

    2004-01-01

    and other low-γ nuclei. Subsequent to the DNP process, the solid sample is dissolved rapidly with a warm solvent to create a solution of molecules with highly polarized nuclear spins. Two main applications are proposed: high-resolution liquid state NMR with enhanced sensitivity, and the use......A method to generate strongly polarized nuclear spins in solution has been developed, using Dynamic Nuclear Polarization (DNP) at a temperature of 1.2K, and at a field of 3.354T, corresponding to an electron spin resonance frequency of 94GHz. Trityl radicals are used to directly polarize 13C...

  10. Recent trends in high spin sensitivity magnetic resonance

    Science.gov (United States)

    Blank, Aharon; Twig, Ygal; Ishay, Yakir

    2017-07-01

    new ideas, show how these limiting factors can be mitigated to significantly improve the sensitivity of induction detection. Finally, we outline some directions for the possible applications of high-sensitivity induction detection in the field of electron spin resonance.

  11. High-spin states of 125Sb: Particle-core excitation coupling

    Institute of Scientific and Technical Information of China (English)

    LIU; Zhong; (

    2003-01-01

    [1]Fogelberg, B., Carle, P., Levels and transition probabilities in 120,122,124,126,128Sn studied in the decay of In isotopes, Nucl. Phys. A, 1979, 323: 205-252.[2]Broda, R., Mayer, R. H., Bearden, I. G. et al., Yrast isomers in tin nuclei from heavy ion collisions and the νh11/2 subshell filling, Phys. Rev. Lett., 1992, 68: 1671-1674.[3]Stone, C. A., Walters, W. B., Decay of 17-min (19/2)- 129mSb, Z. Phys. A, 1987, 328: 257-258.[4]Genevey, J., Pinston, J. A., Faust, H., New high-spin microsecond isomers in 131Sb, Eur. Phys. J., 2000, A9: 191-195.[5]Shroy, R. E., Gaigalas, A. K., Schatz, G. et al., High-spin states in odd-mass 113-119Sb: △J = 1 bands on 9/2+ proton-hole states, Phys. Rev. C, 1979, 19: 1324-1343.[6]Lunardi, S., Daly, P. J., Soramel, F. et al., Decay of (Vh11/2n)10+ and (πd5/2Vh11/2n)25/2+ isomers in even-A Sn and odd-A Sb nuclei, Z. Phys. A, 1987, 328: 487-492.[7]Piel, W. F. Jr., Chowdhury, P., Garg, U. et al., Collective structures in the odd-Z transitional nuclei 115,117I and 121,123Sb, Phys. Rev. C, 1985, 31: 456-464.[8]Katakura, J., Nuclear data sheets for A = 125. Nuclear Data Sheets, 1999, 86: 981-990.[9]Morinaga, H., Yamazaki, T., In-beam Gamma-ray Spectroscopy, Amsterdam: North-Holland Publishing Company, 1976, 324-332.[10]Zhang, C. T., Bhattacharyya, P., Daly, P. J. et al., Yrast excitations in A = 126-131 Te nuclei from deep inelastic 130Te + 64Ni reactions, Nucl. Phys. A, 1998, 628: 386-402.[11]Apt, K. E., Walters, W. B., Radioactive decay of 2.2-h 127Sn to levels of 127Sb, Phys. Rev. C, 1974, 9: 310-325.[12]Jonsson, N. -G., Backlin, A., Kantele, J. et al., Collective states in even Sn nuclei, Nucl. Phys. A, 1981, 371: 333-348.[13]Vanden, G., Berghe, H. K., Structure and electromagnetic properties of the odd-A antimony isotopes in a unified-model calculation, Nucl. Phys. A,1971, 163: 478-512.[14]Blomqvist, J., Kleinheinz, P., Daly, P. J., Atomic masses above 146Gd derived from a

  12. Effects of GFF Bands on Normal and High Strength Concrete Cylinders

    OpenAIRE

    Jayaprakash, J; Abdul Aziz Abdul Samad; Noridah Mohamad; K.K. Choong; M.J. Megat Azmi; H.A.B. Badorul

    2010-01-01

    This paper exemplifies the effects of externally confined Glass Fibre Fabric (GFF) bands on normal and high strength concrete cylinders. Twelve normal and high strength concrete cylinders were cast and tested in the laboratory environment under axial compression to failure. The experimental results show that the degree of confinement of discrete GFF confined high strength concrete cylinders was significantly better than normal strength concrete cylinders with GFF bands, however...

  13. High-spin states in /sup 86/Y

    Energy Technology Data Exchange (ETDEWEB)

    Bucurescu, D.; Constantinescu, G.; Cutiou, D.; Ivascu, M.; Zamfir, N.V.; Haliem, A.A. (Institutul Central de Fizica, Bucharest (Romania))

    1984-09-01

    The level scheme of /sup 86/Y was investigated by ..gamma..-ray spectroscopy with /sup 76/Ge(/sup 14/N, 4n) and /sup 73/Ge(/sup 16/O,p2n) reactions. New energy levels, spins and parities in the yrast sequence above the known isomeric 8+ states were indicated. The possible structure of these states is discussed in connection with an observed similarity with the yrast states in both odd and even-even neighbouring nuclei.

  14. Paramagnetic properties of the low- and high-spin states of yeast cytochrome c peroxidase

    Energy Technology Data Exchange (ETDEWEB)

    Vanwetswinkel, Sophie; Nuland, Nico A. J. van; Volkov, Alexander N., E-mail: ovolkov@vub.ac.be [Vrije Universiteit Brussel, Jean Jeener NMR Centre, Structural Biology Brussels (Belgium)

    2013-09-15

    Here we describe paramagnetic NMR analysis of the low- and high-spin forms of yeast cytochrome c peroxidase (CcP), a 34 kDa heme enzyme involved in hydroperoxide reduction in mitochondria. Starting from the assigned NMR spectra of a low-spin CN-bound CcP and using a strategy based on paramagnetic pseudocontact shifts, we have obtained backbone resonance assignments for the diamagnetic, iron-free protein and the high-spin, resting-state enzyme. The derived chemical shifts were further used to determine low- and high-spin magnetic susceptibility tensors and the zero-field splitting constant (D) for the high-spin CcP. The D value indicates that the latter contains a hexacoordinate heme species with a weak field ligand, such as water, in the axial position. Being one of the very few high-spin heme proteins analyzed in this fashion, the resting state CcP expands our knowledge of the heme coordination chemistry in biological systems.

  15. Development of high-pressure, high-field and multifrequency electron spin resonance system.

    Science.gov (United States)

    Sakurai, T; Taketani, A; Tomita, T; Okubo, S; Ohta, H; Uwatoko, Y

    2007-06-01

    The electron spin resonance (ESR) system which covers the magnetic field region up to 16 T, the quasicontinuous frequency region from 60 to 700 GHz, the temperature region from 1.8 to 4.2 K, and the hydrostatic pressure region up to 1.1 GPa has been developed. This is the first pulsed high-field and multifrequency ESR system with the pressure region over 1 GPa as far as we know. Transmission ESR spectra under hydrostatic pressure can be obtained by combining a piston-cylinder-type pressure cell and the pulsed magnetic field ESR apparatus. The pressure cell consists of a NiCrAl cylinder and sapphire or zirconia inner parts. The use of sapphire or zirconia as inner parts enables us to observe ESR under pressure because these inner parts have high transmittance for the electromagnetic wave with millimeter and submillimeter wavelengths. We have successfully applied this system for the pressure dependence measurements of an isolated spin system NiSnCl(6)6H(2)O up to 1.1 GPa. It was found that the single ion anisotropy parameter D of this compound strongly depends on pressure. The parameter D is approximately proportional to the pressure up to 0.75 GPa, and the relation between D and the pressure can be used for the pressure calibration of this high-field and high-pressure ESR system.

  16. High Performance Ka Band Power Amplifiers for Future EVA Radio Applications Project

    Data.gov (United States)

    National Aeronautics and Space Administration — In this proposal, AlphaSense, Inc. and the University of Washington detail the development of a novel, high performance Ka band power amplifier for EVA radio...

  17. High-power X- and Ka-band Gallium Nitride Amplifiers with Exceptional Efficiency Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Achieving very high-power amplification with maximum efficiency at X- and Ka-band is challenging using solid-state technology. Gallium Arsenide (GaAs) has been the...

  18. High Power Combiner/Divider Design for Dual Band RF Power Amplifiers

    OpenAIRE

    Flattery, Kyle; Amin, Shoaib; Rönnow, Daniel; Mahamat, Yaya; Eroglu, Abdullah

    2015-01-01

    Design of low loss with an enhanced thermal profile power divider/combiner for high power dual-band Radio Frequency (RF) power amplifier applications is given. The practical implementation, low loss and substrate characteristics make this type of combiner ideal for high power microwave applications.  The combiner operational frequencies are chosen to operate at 900 MHz and 2.14 GHz, which are common frequencies for concurrent dual band RF power amplifiers. The analytical results are verified ...

  19. Even-parity spin-triplet paired states by combined effect of Hund's rule and correlations in two-band Hubbard model: a brief overview

    Science.gov (United States)

    Zegrodnik, Michał

    2015-02-01

    Universal aspects of the Hund's rule induced spin-triplet pairing are analysed within the two-band Hubbard model on a square lattice. According to our calculations, this pairing mechanism in conjunction with the correlation effect can result in stability of the paired phase in the so-called purely repulsive interactions regime, in which there is no effectively attractive interaction. Furthermore, even though all of the interaction terms are of intrasite character, the pairing contains both intra- and inter-site components. In effect, the gap parameter has a mixture of s-wave and extended s-wave symmetries. The calculations have been carried out with the use of the Statistically Consistent Gutzwiller Approximation developed by us in recent years.

  20. A model for shear-band formation and high-explosive initiation in a hydrodynamics code

    Energy Technology Data Exchange (ETDEWEB)

    Kerrisk, J.F.

    1996-03-01

    This report describes work in progress to develop a shear band model for MESA-2D. The object of this work is (1) to predict the formation of shear bands and their temperature in high explosive (HE) during a MESA-2D calculation, (2) to then assess whether the HE would initiate, and (3) to allow a detonation wave initiated from a shear band to propagate. This requires developing a model that uses average cell data to estimate the size and temperature of narrow region (generally much narrower than the cell size) that is undergoing shear within the cell. The shear band temperature (rather than the average cell temperature) can be used to calculate the flow stress of the material in the cell or to calculate heat generation from reactive materials. Modifications have been made to MESA-2D to calculate shear band size and temperature, and to initiate HE detonation when conditions warrant. Two models have been used for shear-band size and temperature calculation, one based on an independent estimate of the shear band width and a second based on the temperature distribution around the shear band. Both models have been tested for calculations in which shear band formation occurs in steel. A comparison of the measured and calculated local temperature rise in a shear band has been made. A model for estimating the time to initiation of the HE based on the type of HE and the temperature distribution in a shear band has also been added to MESA-2D. Calculations of conditions needed to initiate HE in projectile-impact tests have been done and compared with experimental data. Further work is d to test the model.

  1. Linear Polarization Measurements for High-Spin States in 146Gd

    CERN Document Server

    Krishichayan,; Basu, S K; Bhowmik, R K; Chakraborty, A; Chaturvedi, L; Dhal, A; Garg, U; Ghugre, S S; Goswami, R; Jhingan, A; Madhvan, N; Rao, P V Madhusudhana; Mukhopadhyay, S; Muralithar, S; Nath, S; Pattabiraman, N S; Ray, S; Saha, S; Sarkar, M Saha; Sarkar, S; Singh, R; Singh, R P; Sinha, A K; Sinha, R K; Sugathan, P; Yogi, B K

    2013-01-01

    A {\\gamma}-ray linear polarization measurement has been performed to directly determine the parities for the levels in 146Gd nucleus. High-spin states in this nucleus were populated in a reaction 115In + 34S at 140 MeV incident energy. Linearly polarized {\\gamma} - rays emitted from oriented states were measured using a Compton polarimeter consisting of an array of 8 Compton-suppressed Clover detectors. Unambiguous assignments of the spin and parity have been made for most of the observed levels and changes made in the previously reported spin-parity assignments for a few levels. Shell model calculations performed with judicious truncation over the {\\pi}(gdsh) valence space interpret the structure of only the low-lying levels up to J{\\pi} = 19+ and 9-. N = 82 neutron-core breaking is found to be essential for high spin states with excitation energies Ex > 7 MeV.

  2. STRUCTURE EVOLUTION OF POLYMER CHAINS FOR NECKING FORMATION IN HIGH-SPEED FIBER SPINNING PROCESS

    Institute of Scientific and Technical Information of China (English)

    Hong Zheng; Wei Yu; Hong-bin Zhang; Chi-xing Zhou

    2006-01-01

    Finite element method is used to simulate the high-speed melt spinning process, based on the equation system proposed by Doufas et al. Calculation predicts a neck-like deformation, as well as the related profiles of velocity, diameter, temperature, chain orientation, and crystallinity in the fiber spinning process. Considering combined effects on the process such as flow-induced crystallization, viscoelasticity, filament cooling, air drag, inertia, surface tension and gravity, the simulated material flow behaviors are consistent with those observed for semi-crystalline polymers under various spinning conditions. The structure change of polymer coils in the necking region described by the evolution of conformation tensor is also investigated. Based on the relaxation mechanism of macromolecules in flow field different types of morphology change of polymer chains before and in the neck are proposed, giving a complete prospect of structure evolution and crystallization of semi-crystalline polymer in the high speed fiber spinning process.

  3. Production of High Performance Bioinspired Silk Fibers by Straining Flow Spinning.

    Science.gov (United States)

    Madurga, Rodrigo; Gañán-Calvo, Alfonso M; Plaza, Gustavo R; Guinea, Gustavo V; Elices, Manuel; Pérez-Rigueiro, José

    2017-04-10

    In the last years, there has been an increasing interest in bioinspired approaches for different applications, including the spinning of high performance silk fibers. Bioinspired spinning is based on the natural spinning system of spiders and worms and requires combining changes in the chemical environment of the proteins with the application of mechanical stresses. Here we present the novel straining flow spinning (SFS) process and prove its ability to produce high performance fibers under mild, environmentally friendly conditions, from aqueous protein dopes. SFS is shown to be an extremely versatile technique which allows controlling a large number of processing parameters. This ample set of parameters allows fine-tuning the microstructure and mechanical behavior of the fibers, which opens the possibility of adapting the fibers to their intended uses.

  4. Coherent manipulation of an ensemble of nuclear spins in diamond for high precision rotation sensing

    Science.gov (United States)

    Jaskula, Jean-Christophe; Saha, Kasturi; Ajoy, Ashok; Cappellaro, Paola

    2016-05-01

    Gyroscopes find wide applications in everyday life from navigation and inertial sensing to rotation sensors in hand-held devices and automobiles. Current devices, based on either atomic or solid-state systems, impose a choice between long-time stability and high sensitivity in a miniaturized system. We are building a solid-state spin gyroscope associated with the Nitrogen-Vacancy (NV) centers in diamond take advantage of the efficient optical initialization and measurement offered by the NV electronic spin and the stability and long coherence time of the nuclear spin, which is preserved even at high defect density. In addition, we also investigate electro-magnetic noise monitoring and feedback schemes based on the coupling between the NV electronic and nuclear spin to achieve higher stability.

  5. New high spin states and isomers in the {sup 208}Pb and {sup 207}Pb nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Broda, R.; Wrzesinski, J.; Pawlat, T. [and others

    1996-12-31

    The two most prominent examples of the heavy doubly closed shell (DCS) nuclei, {sup 208}Pb and {sup 132}Sn, are not accessible by conventional heavy-ion fusion processes populating high-spin states. This experimental difficulty obscured for a long time the investigation of yrast high-spin states in both DCS and neighboring nuclei and consequently restricted the study of the shell model in its most attractive regions. Recent technical development of multidetector gamma arrays opened new ways to exploit more complex nuclear processes which populate the nuclei of interest with suitable yields for gamma spectroscopy and involve population of moderately high spin states. This new possibility extended the range of accessible spin values and is a promising way to reach new yrast states. Some of these states are expected to be of high configurational purity and can be a source of important shell model parameters which possibly can be used later to check the validity of the spherical shell model description at yet higher spin and higher excitation energy. The nuclei in the closest vicinity of {sup 132}Sn are produced in spontaneous fission and states with spin values up to I=14 can be reached in fission gamma spectroscopy studies with the presently achieved sensitivity of gamma arrays. New results on yrast states in the {sup 134}Te and {sup 135}I nuclei populated in fission of the {sup 248}Cm presented at this conference illustrate such application of the resolving power offered by modern gamma techniques.

  6. Doping dependence of spin excitations and its correlations with high-temperature superconductivity in iron pnictides.

    Science.gov (United States)

    Wang, Meng; Zhang, Chenglin; Lu, Xingye; Tan, Guotai; Luo, Huiqian; Song, Yu; Wang, Miaoyin; Zhang, Xiaotian; Goremychkin, E A; Perring, T G; Maier, T A; Yin, Zhiping; Haule, Kristjan; Kotliar, Gabriel; Dai, Pengcheng

    2013-01-01

    High-temperature superconductivity in iron pnictides occurs when electrons and holes are doped into their antiferromagnetic parent compounds. Since spin excitations may be responsible for electron pairing and superconductivity, it is important to determine their electron/hole-doping evolution and connection with superconductivity. Here we use inelastic neutron scattering to show that while electron doping to the antiferromagnetic BaFe₂As₂ parent compound modifies the low-energy spin excitations and their correlation with superconductivity (100 meV), hole-doping suppresses the high-energy spin excitations and shifts the magnetic spectral weight to low-energies. In addition, our absolute spin susceptibility measurements for the optimally hole-doped iron pnictide reveal that the change in magnetic exchange energy below and above T(c) can account for the superconducting condensation energy. These results suggest that high-T(c) superconductivity in iron pnictides is associated with both the presence of high-energy spin excitations and a coupling between low-energy spin excitations and itinerant electrons.

  7. Valence band structure of binary chalcogenide vitreous semiconductors by high-resolution XPS

    Energy Technology Data Exchange (ETDEWEB)

    Kozyukhin, S., E-mail: sergkoz@igic.ras.ru [Russian Academy of Science, Institute of General and Inorganic Chemistry (Russian Federation); Golovchak, R. [Lviv Scientific Research Institute of Materials of SRC ' Carat' (Ukraine); Kovalskiy, A. [Lehigh University, Department of Materials Science and Engineering (United States); Shpotyuk, O. [Lviv Scientific Research Institute of Materials of SRC ' Carat' (Ukraine); Jain, H. [Lehigh University, Department of Materials Science and Engineering (United States)

    2011-04-15

    High-resolution X-ray photoelectron spectroscopy (XPS) is used to study regularities in the formation of valence band electronic structure in binary As{sub x}Se{sub 100-x}, As{sub x}S{sub 100-x}, Ge{sub x}Se{sub 100-x} and Ge{sub x}S{sub 100-x} chalcogenide vitreous semiconductors. It is shown that the highest occupied energetic states in the valence band of these materials are formed by lone pair electrons of chalcogen atoms, which play dominant role in the formation of valence band electronic structure of chalcogen-rich glasses. A well-expressed contribution from chalcogen bonding p electrons and more deep s orbitals are also recorded in the experimental valence band XPS spectra. Compositional dependences of the observed bands are qualitatively analyzed from structural and compositional points of view.

  8. EPR studies on branched high-spin arylnitrenes.

    Science.gov (United States)

    Chapyshev, Sergei V; Korchagin, Denis V; Budyka, Mikhail F; Gavrishova, Tatiana N; Neuhaus, Patrik; Sander, Wolfram

    2012-08-06

    The UV (λ>305 nm) photolysis of triazide 3 in 2-methyl-tetrahydrofuran glass at 7 K selectively produces triplet mononitrene 4 (g=2.003, D(T)=0.92 cm(-1), E(T)=0 cm(-1)), quintet dinitrene 6 (g=2.003, D(Q)=0.204 cm(-1), E(Q)=0.035 cm(-1)), and septet trinitrene 8 (g=2.003, D(S)=-0.0904 cm(-1), E(S) =-0.0102 cm(-1)). After 45 min of irradiation, the major products are dinitrene 6 and trinitrene 8 in a ratio of ∼1:2, respectively. These nitrenes are formed as mixtures of rotational isomers each of which has slightly different magnetic parameters D and E. The best agreement between the line-shape spectral simulations and the experimental electron paramagnetic resonance (EPR) spectrum is obtained with the line-broadening parameters Γ(E(Q))=180 MHz for dinitrene 6 and Γ(E(S))=330 MHz for trinitrene 8. According to these line-broadening parameters, the variations of the angles Θ in rotational isomers of 6 and 8 are expected to be about ±1 and ±3°, respectively. Theoretical estimations of the magnetic parameters obtained from PBE/DZ(COSMO)//UB3LYP/6-311+G(d,p) calculations overestimate the E and D values by 1 and 8 %, respectively. Despite the large distances between the nitrene units and the extended π systems, the zero field splitting (zfs) parameters D are found to be close to those in quintet dinitrenes and septet trinitrenes, where the nitrene centers are attached to the same aryl ring. The large D values of branched septet nitrenes are due to strong negative one-center spin-spin interactions in combination with weak positive two-center spin-spin interactions, as predicted by theoretical considerations. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. High-Power Ka-Band Window and Resonant Ring

    Energy Technology Data Exchange (ETDEWEB)

    Jay L. Hirshfield

    2006-11-29

    A stand-alone 200 MW rf test station is needed for carrying out development of accelerator structures and components for a future high-gradient multi-TeV collider, such as CLIC. A high-power rf window is needed to isolate the test station from a structure element under test. This project aimed to develop such a window for use at a frequency in the range 30-35 GHz, and to also develop a high-power resonant ring for testing the window. During Phase I, successful conceptual designs were completed for the window and the resonant ring, and cold tests of each were carried out that confirmed the designs.

  10. A Minimized MIMO-UWB Antenna with High Isolation and Triple Band-Notched Functions

    Science.gov (United States)

    Kong, Yuanyuan; Li, Yingsong; Yu, Kai

    2016-11-01

    A compact high isolation MIMO-UWB antenna with triple frequency rejection bands is proposed for UWB communication applications. The proposed MIMO-UWB antenna consists of two identical UWB antennas and each antenna element has a semicircle ring shaped radiation patch fed by a bend microstrip feeding line for covering the UWB band, which operates from 2.85 GHz to 11.79 GHz with an impedance bandwidth of 122.1 %. By etching a L-shaped slot on the ground plane, and embedding an "anchor" shaped stub into the patch and integrating an open ring under the semicircle shaped radiation patch, three notch bands are realized to suppress WiMAX (3.3-3.6 GHz), WLAN(5.725-5.825 GHz) and uplink of X-band satellite (7.9-8.4 GHz) signals. The high isolation with S21<-20 dB in most UWB band is obtained by adding a protruded decoupling structure. The design procedure of the MIMO-UWB antenna is given in detail. The proposed MIMO-UWB antenna is simulated, fabricated and measured. Experimental results demonstrate that the proposed MIMO-UWB antenna has a stable gain, good impedance match, high isolation, low envelope correlation coefficient and good radiation pattern at the UWB operating band and it can provide three designated notch bands.

  11. Vortical fluid and $\\Lambda$ spin correlations in high-energy heavy-ion collisions

    CERN Document Server

    Pang, Long-Gang; Wang, Qun; Wang, Xin-Nian

    2016-01-01

    Fermions become polarized in a vortical fluid due to spin-vorticity coupling. The spin polarization density is proportional to the local fluid vorticity at the next-to-leading order of a gradient expansion in a quantum kinetic theory. Spin correlations of two $\\Lambda$-hyperons can therefore reveal the vortical structure of the dense matter in high-energy heavy-ion collisions. We employ a (3+1)D viscous hydrodynamic model with event-by-event fluctuating initial conditions from A MultiPhase Transport (AMPT) model to calculate the vorticity distributions and $\\Lambda$ spin correlations. The azimuthal correlation of the transverse spin is shown to have a cosine form plus an offset due to a circular structure of the transverse vorticity around the beam direction and global spin polarization. The longitudinal spin correlation shows a structure of vortex-pairing in the transverse plane due to the convective flow of hot spots in the radial direction. The dependence on colliding energy, rapidity, centrality and sensi...

  12. First-principles study of spin-polarized electronic band structures in ferromagnetic Zn1-xTMxS (TM = Fe, Co and Ni)

    KAUST Repository

    Saeed, Yasir

    2010-10-01

    We report a first-principles study of structural, electronic and magnetic properties of crystalline alloys Zn1-xTMxS (TM = Fe, Co and Ni) at x = 0.25. Structural properties are computed from the total ground state energy convergence and it is found that the cohesive energies of Zn 1-xTMxS are greater than that of zincblende ZnS. We also study the spin-polarized electronic band structures, total and partial density of states and the effect of TM 3d states. Our results exhibit that Zn 0.75Fe0.25S, Zn0.75Co0.25S and Zn0.75Ni0.25S are half-metallic ferromagnetic with a magnetic moment of 4μB, 3μB and 2μB, respectively. Furthermore, we calculate the TM 3d spin-exchange-splitting energies Δx (d), Δx (x-d), exchange constants N0α and N0β, crystal field splitting (ΔEcrystEt2g-Eeg), and find that p-d hybridization reduces the local magnetic moment of TM from its free space charge value. Moreover, robustness of Zn1-xTMxS with respect to the variation of lattice constants is also discussed. © 2010 Elsevier B.V. All rights reserved.

  13. High-spin level structure of the neutron-rich nucleus 91Y

    CERN Document Server

    He, Xiao-Feng; Fang, Yong-De; Liu, Min-Liang; Zhang, Yu-Hu; Wang, Kai-Long; Wang, Jian-Guo; Guo, Song; Qiang, Yun-Hua; Zheng, Yong; Zhang, Ning-Tao; Li, Guang-Shun; Gao, Bing-Shui; Wu, Xiao-Guang; He, Chuang-Ye; Zheng, Yun

    2015-01-01

    High-spin level structure of the neutron-rich nucleus 91Y has been reinvestigated via the 82Se(13C, p3n)91Y reaction. A newly constructed level scheme including several key levels clarifies the uncertainties in the earlier studies. These levels are characterized by the breaking of the Z=38 and N=56 subshell closures, which involves in the spin-isospin dependent central force and tensor force.

  14. Micro/Nanometer-scale fiber with highly ordered structures by mimicking the spinning process of silkworm.

    Science.gov (United States)

    Chae, Su-Kyoung; Kang, Edward; Khademhosseini, Ali; Lee, Sang-Hoon

    2013-06-11

    A new method for the microfluidic spinning of ultrathin fibers with highly ordered structures is proposed by mimicking the spinning mechanism of silkworms. The self-aggregation is driven by dipole-dipole attractions between polar polymers upon contact with a low-polarity solvent to form fibers with nanostrands. The induction of Kelvin-Helmholtz instabilities at the dehydrating interface between two miscible fluids generates multi-scale fibers in a single microchannel.

  15. On the calculation of high-spin states in the full configuration-interaction formalism

    Energy Technology Data Exchange (ETDEWEB)

    Bendazzoli, Gian Luigi [Dipartimento di Chimica Fisica e Inorganica, Universita di Bologna, Viale Risorgimento 4, I-40136 Bologna (Italy); Deguilhem, Benjamin; Evangelisti, Stefano; Gadea, Florent Xavier; Leininger, Thierry [Universite de Toulouse et CNRS, Laboratoire de Chimie et Physique Quantiques, 118, Route de Narbonne, F-31062 Toulouse Cedex (France); Monari, Antonio [Dipartimento di Chimica Fisica e Inorganica, Universita di Bologna, Viale Risorgimento 4, I-40136 Bologna (Italy)], E-mail: amonari@ms.fci.unibo.it

    2008-06-02

    A modified electronic Hamiltonian that allows the calculations of high-spin eigenfunctions in the S{sub z}=0 manifold, is presented. In this formalism the low-spin states are shifted in energy while all the states having a multiplicity larger than a given value are kept untouched. This formalism has been applied to a test calculations of the lowest quintet state of the helium dimer and of the quintet state of the tetrahedral Li{sub 4} cluster.

  16. Probing spin frustration in high-symmetry magnetic nanomolecules by inelastic neutron scattering

    DEFF Research Database (Denmark)

    Garlea, V.O.; Nagler, S.E.; Zarestky, J.L.;

    2006-01-01

    Low temperature inelastic neutron scattering studies have been performed to characterize the low energy magnetic excitation spectrum of the magnetic nanomolecule {Mo(72)Fe(30)}. This unique highly symmetric cluster features spin frustration and is one of the largest discrete magnetic molecules st...... of the temperature dependence of the observed neutron scattering are explained by a quantum model of the frustrated spin cluster. However, no satisfactory theoretical explanation is yet available for the observed magnetic field dependence....

  17. High-spin states in the sup 9 sup 7 Tc nucleus

    CERN Document Server

    Bucurescu, D; Cata-Danil, I; Ivascu, M; Marginean, N; Rusu, C; Stroe, L; Ur, C A; Gadea, A

    2003-01-01

    High-spin states in the sup 9 sup 7 Tc nucleus have been studied by in-beam gamma-ray spectroscopy with the reaction sup 8 sup 2 Se( sup 1 sup 9 F,4n gamma) at 68 MeV incident energy. Excited states have been observed up to about 8 MeV excitation and spin 43/2 Planck constant. The observed level scheme is compared with results of shell model calculations. (orig.)

  18. Tailoring the spin waves band structure of 1D magnonic crystals consisting of L-shaped iron/permalloy nanowires

    Science.gov (United States)

    Gubbiotti, G.; Silvani, R.; Tacchi, S.; Madami, M.; Carlotti, G.; Yang, Z.; Adeyeye, A. O.; Kostylev, M.

    2017-03-01

    We have investigated both experimentally and numerically the magnonic band structure of arrays of closely spaced Fe/permalloy nanowires (NWs) with an L-shape cross-section using the Brillouin light scattering technique and GPU-based micromagnetic simulations. NWs consist of a 340 nm wide and 10 nm thick permalloy layer covered by a 170 nm wide Fe overlayer. The thickness of the latter was varied in the range from 0 to 10 nm in order to analyze its influence on the magnonic band structure. We found that both the frequency and the spatial profile of the most intense and dispersive mode, can be efficiently tuned by the presence of the thin Fe NW overlayer. In particular, by increasing the Fe thickness, one observes a substantial frequency increase, while the spatial profile of the mode narrows and moves to the permalloy NW portion not covered by Fe. In addition, the presence of the Fe overlayer causes a significant increase of the number of detected modes and a change of their intensity in the Brillouin spectra as a function of the Bloch wave number. These results show that it is possible to engineer the band structure of magnonic crystals consisting of bi-layered, L-shaped, NWs by a careful control of the overlayer thickness.

  19. Design and Validation of High Date Rate Ka-Band Software Defined Radio for Small Satellite

    Science.gov (United States)

    Xia, Tian

    2016-01-01

    The Design and Validation of High Date Rate Ka- Band Software Defined Radio for Small Satellite project will develop a novel Ka-band software defined radio (SDR) that is capable of establishing high data rate inter-satellite links with a throughput of 500 megabits per second (Mb/s) and providing millimeter ranging precision. The system will be designed to operate with high performance and reliability that is robust against various interference effects and network anomalies. The Ka-band radio resulting from this work will improve upon state of the art Ka-band radios in terms of dimensional size, mass and power dissipation, which limit their use in small satellites.

  20. Calibration for Relative Interior Orientation Relationship and Band-to-band Registration with High Accuracy of ZY-3 Multi-spectral Image

    Directory of Open Access Journals (Sweden)

    LI Qijun

    2016-06-01

    Full Text Available Using high accuracy match points extracted between the multi-spectral images that obtained at the same time,a position model of the CCD chips of the ZY-3 multi-spectral camera was proposed. Relative interior orientation relationship parameters were calculated and accurate band-to-band automatic registration of ZY-3 multi-spectral image was achieved based on the position model. The experimental result indicates that the band-to-band automatic registration accuracy of ZY-3 multi-spectral image is better than 0.3 pixels with the proposed method.

  1. X-ray Absorption Spectroscopic Studies of High-Spin Nonheme (Alkylperoxo)iron(III) Intermediates

    Energy Technology Data Exchange (ETDEWEB)

    Shan,X.; Rohde, J.; Koehntop, K.; Zhou, Y.; Bukowski, M.; Costas, M.; Fujisawa, K.; Que, Jr., L.

    2007-01-01

    The reactions of iron(II) complexes [Fe(Tpt-Bu,i-Pr)(OH)] (1a, Tpt-Bu,i-Pr = hydrotris(3-tert-butyl-5-isopropyl-1-pyrazolyl)borate), [Fe(6-Me2BPMCN)(OTf)2] (1b, 6-Me2BPMCN = N,N'-bis((2-methylpyridin-6-yl)methyl)-N,N'-dimethyl-trans-1,2-diaminocyclohexane), and [Fe(L8Py2)(OTf)](OTf) (1c, L8Py2 = 1,5-bis(pyridin-2-ylmethyl)-1,5-diazacyclooctane) with tert-BuOOH give rise to high-spin FeIII-OOR complexes. X-ray absorption spectra (XAS) of these high-spin species show characteristic features, distinct from those of low-spin Fe-OOR complexes. These include (1) an intense 1s {yields} 3d preedge feature, with an area around 20 units, (2) an edge energy, ranging from 7122 to 7126 eV, that is affected by the coordination environment, and (3) a 1.86-1.96 Angstroms Fe-OOR bond, compared to the 1.78 Angstroms Fe-OOR bond in low-spin complexes. These unique features likely arise from a flexible first coordination sphere in those complexes. The difference in Fe-OOR bond length may rationalize differences in reactivity between low-spin and high-spin FeIII-OOR species.

  2. Fabrication of highly aligned fibrous scaffolds for tissue regeneration by centrifugal spinning technology

    Energy Technology Data Exchange (ETDEWEB)

    Loordhuswamy, Amalorpava Mary [Department of Textile Technology, Anna University, Chennai 600025 (India); Krishnaswamy, Venkat Raghavan; Korrapati, Purna Sai [Department of Biomaterials, CSIR-Central Leather Research Institute, Chennai 600020 (India); Thinakaran, Senthilram [Department of Textile Technology, Anna University, Chennai 600025 (India); Rengaswami, Giri Dev Venkateshwarapuram, E-mail: vrgiridev@yahoo.com [Department of Textile Technology, Anna University, Chennai 600025 (India)

    2014-09-01

    Centrifugal spinning (C-Spin) is an emerging technology which uses centrifugal force to produce ultrafine fibers. Being a voltage free technique it can overcome the limitations of electrospinning. Owing to the unique characteristic features such as high surface area to volume ratio, porosity, mechanical strength and fiber alignment, centrifugal spun (C-spun) fibrous mat has a wide range of scope in various biomedical applications. Higher degree of fiber alignment can be effortlessly achieved by the C-Spin process. In order to prove the versatility of C-Spin system with respect to fiber alignment, Polycaprolactone (PCL) and gelatin were spun taking them as model polymers. The morphological analysis revealed that highly aligned ultrafine fibers with smooth surface are achieved by C-Spinning. Hydrophilicity, porosity and mechanical property results confirm that the C-spun mat is more suitable for tissue engineering applications. In vitro and in vivo experiments proved that the scaffolds are biocompatible and can be efficiently used as a wound dressing material. - Highlights: • Highly aligned PCL/gelatin fibrous scaffolds were prepared by C-Spinning system. • Degree of fiber alignment was influenced by the proportion of gelatin in the blends. • Direction of cell growth was parallel to the direction of fiber alignment. • C-Spun matrices can efficiently accelerate faster wound healing.

  3. Symmetrization driven spin transition in ɛ-FeOOH at high pressure

    Science.gov (United States)

    Gleason, A. E.; Quiroga, C. E.; Suzuki, A.; Pentcheva, R.; Mao, W. L.

    2013-10-01

    Structural and electronic spin transitions in high-pressure ε-FeOOH are studied using a combination of high pressure X-ray emission spectroscopy (XES), X-ray diffraction (XRD) and density functional theory (DFT) calculations. Using XES, a high- to low-spin transition in trivalent iron is found in ε-FeOOH on compression between 40 and 60 GPa. This is accompanied by a sudden discontinuity in unit cell volume at 53(±2) GPa, obtained from XRD data collected over the same compression range. These results are consistent with DFT calculations using an on-site Coulomb repulsion term (GGA+U), which predict a spin transition in ε-FeOOH at 64.8 GPa. A second order phase transition from P21nm to Pnnm is predicted from DFT at ∼43 GPa and evidenced in the XRD data from the anisotropic stiffening of the lattice parameters around the spin transition. In addition, the DFT results give evidence that the spin collapse is assisted by symmetrization of hydrogen bonds during the transition from P21nm to Pnnm. As the presence of hydrogen, even in small quantities, can affect phase relations, melting temperature, rheology, and other key properties of the Earth's mantle, our study unveils a connection between water (hydroxyl) content and the spin-transition pressure of Fe3+ in the Earth's mantle.

  4. Performance of high-resolution X-band radar for rainfall measurement in The Netherlands

    Directory of Open Access Journals (Sweden)

    C. Z. van de Beek

    2010-02-01

    Full Text Available This study presents an analysis of 195 rainfall events gathered with the X-band weather radar SOLIDAR and a tipping bucket rain gauge network near Delft, The Netherlands, between May 1993 and April 1994. The aim of this paper is to present a thorough analysis of a climatological dataset using a high spatial (120 m and temporal (16 s resolution X-band radar. This makes it a study of the potential for high-resolution rainfall measurements with non-polarimetric X-band radar over flat terrain. An appropriate radar reflectivity – rain rate relation is derived from measurements of raindrop size distributions and compared with radar – rain gauge data. The radar calibration is assessed using a long-term comparison of rain gauge measurements with corresponding radar reflectivities as well as by analyzing the evolution of the stability of ground clutter areas over time. Three different methods for ground clutter correction as well as the effectiveness of forward and backward attenuation correction algorithms have been studied. Five individual rainfall events are discussed in detail to illustrate the strengths and weaknesses of high-resolution X-band radar and the effectiveness of the presented correction methods. X-band radar is found to be able to measure the space-time variation of rainfall at high resolution, far greater than what can be achieved by rain gauge networks or a typical operational C-band weather radar. On the other hand, SOLIDAR can suffer from receiver saturation, wet radome attenuation as well as signal loss along the path. During very strong convective situations the signal can even be lost completely. In combination with several rain gauges for quality control, high resolution X-band radar is considered to be suitable for rainfall monitoring over relatively small (urban catchments. These results offer great prospects for the new high resolution polarimetric doppler X-band radar IDRA.

  5. High broad-band photoresponsivity of mechanically formed InSe-graphene van der Waals heterostructures.

    Science.gov (United States)

    Mudd, Garry W; Svatek, Simon A; Hague, Lee; Makarovsky, Oleg; Kudrynskyi, Zakhar R; Mellor, Christopher J; Beton, Peter H; Eaves, Laurence; Novoselov, Kostya S; Kovalyuk, Zakhar D; Vdovin, Evgeny E; Marsden, Alex J; Wilson, Neil R; Patanè, Amalia

    2015-07-01

    High broad-band photoresponsivity of mechanically formed InSe-graphene van der Waals heterostructures is achieved by exploiting the broad-band transparency of graphene, the direct bandgap of InSe, and the favorable band line up of InSe with graphene. The photoresponsivity exceeds that for other van der Waals heterostructures and the spectral response extends from the near-infrared to the visible spectrum. © 2015 The Authors. Published by WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. A high-field adiabatic fast passage ultracold neutron spin flipper for the UCNA experiment

    Energy Technology Data Exchange (ETDEWEB)

    Holley, A. T.; Pattie, R. W.; Young, A. R. [Department of Physics, North Carolina State University, Raleigh, North Carolina 27695 (United States); Broussard, L. J. [Department of Physics, Duke University, Durham, North Carolina 27708 (United States); Davis, J. L.; Ito, T. M.; Lyles, J. T. M.; Makela, M.; Morris, C. L.; Mortensen, R.; Saunders, A. [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Hickerson, K.; Mendenhall, M. P. [W. K. Kellogg Radiation Laboratory, California Institute of Technology, Pasadena, California 91125 (United States); Liu, C.-Y. [Department of Physics, Indiana University, Bloomington, Indiana 47405 (United States); Mammei, R. R. [Department of Physics, Virginia Tech, Blacksburg, Virginia 24061 (United States); Rios, R. [Department of Physics, Idaho State University, Pocatello, Idaho 83209 (United States)

    2012-07-15

    The UCNA collaboration is making a precision measurement of the {beta} asymmetry (A) in free neutron decay using polarized ultracold neutrons (UCN). A critical component of this experiment is an adiabatic fast passage neutron spin flipper capable of efficient operation in ambient magnetic fields on the order of 1 T. The requirement that it operate in a high field necessitated the construction of a free neutron spin flipper based, for the first time, on a birdcage resonator. The design, construction, and initial testing of this spin flipper prior to its use in the first measurement of A with UCN during the 2007 run cycle of the Los Alamos Neutron Science Center's 800 MeV proton accelerator is detailed. These studies determined the flipping efficiency of the device, averaged over the UCN spectrum present at the location of the spin flipper, to be {epsilon}=0.9985(4).

  7. Ferrimagnetic and Long Period Antiferromagnetic Phases in High Spin Heisenberg Chains with D-Modulation

    Science.gov (United States)

    Hida, Kazuo

    2007-02-01

    The ground state properties of the high spin Heisenberg chains with alternating single site anisotropy are investigated by means of the numerical exact daigonaization and DMRG method. It is found that the ferrimagnetic state appears between the Haldane phase and period doubled Néel phase for the integer spin chains. On the other hand, the transition from the Tomonaga-Luttinger liquid state into the ferrimagnetic state takes place for the half-odd-integer spin chains. In the ferrimagnetic phase, the spontaneous magnetization varies continuously with the modulation amplitude of the single site anisotropy. Eventually, the magnetization is locked to fractional values of the saturated magnetization. These fractional values satisfy the Oshikawa-Yamanaka-Affleck condition. The local spin profile is calculated to reveal the physical nature of each state. In contrast to the case of frustration induced ferrimagnetism, no incommensurate magnetic superstructure is found.

  8. Circular Piezoelectric Accelerometer for High Band Width Application

    DEFF Research Database (Denmark)

    Hindrichsen, Christian Carstensen; Larsen, Jack; Lou-Møller, Rasmus

    2009-01-01

    is used as the sensing material on top of the silicon membrane. Accelerations in the out of plane direction induce a force on the seismic mass bending the membrane and a potential difference is measured in the out of plane direction of the stressed PZT. A resonance frequency of 23.50 kHz, a charge......An uniaxial bulk-micromachined piezoelectric MEMS accelerometer intended for high bandwidth application is fabricated and characterized. A circular seismic mass (radius = 1200 ¿m) is suspended by a 20 ¿m thick annular silicon membrane (radius = 1800 ¿m). A 24 ¿m PZT screen printed thick film...

  9. Isospin symmetry at high spin studied via nucleon knockout from isomeric states

    OpenAIRE

    2016-01-01

    One-neutron knockout reactions have been performed on a beam of radioactive 53Co in a high-spin isomeric state. The analysis is shown to yield highly-selective population of high-spin states in an exotic nucleus with a significant cross section, and hence represents a technique that is applicable to the planned new generation of fragmentation-based radioactive beam facilities. Additionally, the relative cross sections among the excited states can be predicted to a high level of accuracy when ...

  10. A dual-mode microwave resonator for double electron-electron spin resonance spectroscopy at W-band microwave frequencies

    Science.gov (United States)

    Tkach, Igor; Sicoli, Giuseppe; Höbartner, Claudia; Bennati, Marina

    2011-04-01

    We present a dual-mode resonator operating at/near 94 GHz (W-band) microwave frequencies and supporting two microwave modes with the same field polarization at the sample position. Numerical analysis shows that the frequencies of both modes as well as their frequency separation can be tuned in a broad range up to GHz. The resonator was constructed to perform pulsed ELDOR experiments with a variable separation of "pump" and "detection" frequencies up to Δ ν = 350 MHz. To examine its performance, test ESE/PELDOR experiments were performed on a representative biradical system.

  11. High-order moments of spin-orbit energy in a multielectron configuration

    Science.gov (United States)

    Na, Xieyu; Poirier, M.

    2016-07-01

    In order to analyze the energy-level distribution in complex ions such as those found in warm dense plasmas, this paper provides values for high-order moments of the spin-orbit energy in a multielectron configuration. Using second-quantization results and standard angular algebra or fully analytical expressions, explicit values are given for moments up to 10th order for the spin-orbit energy. Two analytical methods are proposed, using the uncoupled or coupled orbital and spin angular momenta. The case of multiple open subshells is considered with the help of cumulants. The proposed expressions for spin-orbit energy moments are compared to numerical computations from Cowan's code and agree with them. The convergence of the Gram-Charlier expansion involving these spin-orbit moments is analyzed. While a spectrum with infinitely thin components cannot be adequately represented by such an expansion, a suitable convolution procedure ensures the convergence of the Gram-Charlier series provided high-order terms are accounted for. A corrected analytical formula for the third-order moment involving both spin-orbit and electron-electron interactions turns out to be in fair agreement with Cowan's numerical computations.

  12. Spin Seebeck effect and spin Hall magnetoresistance at high temperatures for a Pt/yttrium iron garnet hybrid structure

    Science.gov (United States)

    Wang, Shuanhu; Zou, Lvkuan; Zhang, Xu; Cai, Jianwang; Wang, Shufang; Shen, Baogen; Sun, Jirong

    2015-10-01

    Based on unique experimental setups, the temperature dependences of the longitudinal spin Seebeck effect (LSSE) and spin Hall magnetoresistance (SMR) of the Pt/yttrium iron garnet (Pt/YIG) hybrid structure are determined in a wide temperature range up to the Curie temperature of YIG. From a theoretical analysis of the experimental relationship between the SMR and temperature, the spin mixing conductance of the Pt/YIG interface is deduced as a function of temperature. Adopting the deduced spin mixing conductance, the temperature dependence of the LSSE is well reproduced based on the magnon spin current theory. Our research sheds new light on the controversy about the theoretical models for the LSSE.

  13. K-band high power latching switch. [communication satellite system

    Science.gov (United States)

    Mlinar, M. J.; Piotrowski, W. S.; Raue, J. E.

    1980-01-01

    A 19 GHz waveguide latching switch with a bandwidth of 1400 MHz and an exceptionally low insertion loss of 0.25 dB was demonstrated. The RF and driver ferrites are separate structures and can be optimized individually. This analysis for each structure is separately detailed. Basically, the RF section features a dual turnstile junction. The circulator consists of a dielectric tube which contains two ferrite rods, and a dielectric spacer separating the ferrite parts along the center of symmetry of the waveguide to form two turnstiles. This subassembly is indexed and locked in the center of symmetry of a uniform junction of three waveguides by the metallic transformers installed in the top and bottom walls of the housing. The switching junction and its actuating circuitry met all RF performance objectives and all shock and vibration requirements with no physical damage or performance degradation. It exceeds thermal requirements by operating over a 100 C temperature range (-44 C to +56 C) and has a high power handling capability allowing up to 100 W of CW input power.

  14. Highly stable atomic vector magnetometer based on free spin precession.

    Science.gov (United States)

    Afach, S; Ban, G; Bison, G; Bodek, K; Chowdhuri, Z; Grujić, Z D; Hayen, L; Hélaine, V; Kasprzak, M; Kirch, K; Knowles, P; Koch, H-C; Komposch, S; Kozela, A; Krempel, J; Lauss, B; Lefort, T; Lemière, Y; Mtchedlishvili, A; Naviliat-Cuncic, O; Piegsa, F M; Prashanth, P N; Quéméner, G; Rawlik, M; Ries, D; Roccia, S; Rozpedzik, D; Schmidt-Wellenburg, P; Severjins, N; Weis, A; Wursten, E; Wyszynski, G; Zejma, J; Zsigmond, G

    2015-08-24

    We present a magnetometer based on optically pumped Cs atoms that measures the magnitude and direction of a 1 μT magnetic field. Multiple circularly polarized laser beams were used to probe the free spin precession of the Cs atoms. The design was optimized for long-time stability and achieves a scalar resolution better than 300 fT for integration times ranging from 80 ms to 1000 s. The best scalar resolution of less than 80 fT was reached with integration times of 1.6 to 6 s. We were able to measure the magnetic field direction with a resolution better than 10 μrad for integration times from 10 s up to 2000 s.

  15. Nuclear structure and high-spin states of 137Pr

    Science.gov (United States)

    Dragulescu, E.; Ivascu, M.; Petrache, C.; Popescu, D.; Semenescu, G.; Gurgu, I.; Ionescu-Bujor, M.; Iordachescu, A.; Pascovici, G.; Meyer, R. A.; Lopac, V.; Brant, S.; Paar, V.; Vorkapić, D.; Vretenar, D.

    1992-10-01

    Levels in 137Pr were populated in the 126Te( 14N, 3n) and 122Sn( 19F, 4n) reactions and the subsequent radiation was studied using in-beam γ-ray spectroscopy methods including γ-ray excitation-function, angular-distribution, γγ( t) coincidence and γ( t) measurements. A level scheme with new states up to spin {35}/{2} belonging to 137Pr is given. The lifetime of the {11}/{21} state at 563.4 keV has been determined as T {1}/{2} = 2.66±0.07 μ s. The calculation of low-lying levels in 137Pr performed in IBFM has been compared to experimental data.

  16. Devices and process for high-pressure magic angle spinning nuclear magnetic resonance

    Science.gov (United States)

    Hoyt, David W; Sears, Jr., Jesse A; Turcu, Romulus V.F.; Rosso, Kevin M; Hu, Jian Zhi

    2014-04-08

    A high-pressure magic angle spinning (MAS) rotor is detailed that includes a high-pressure sample cell that maintains high pressures exceeding 150 bar. The sample cell design minimizes pressure losses due to penetration over an extended period of time.

  17. A high-resolution, four-band SAR testbed with real-time image formation

    Energy Technology Data Exchange (ETDEWEB)

    Walker, B.; Sander, G.; Thompson, M.; Burns, B.; Fellerhoff, R.; Dubbert, D.

    1996-03-01

    This paper describes the Twin-Otter SAR Testbed developed at Sandia National Laboratories. This SAR is a flexible, adaptable testbed capable of operation on four frequency bands: Ka, Ku, X, and VHF/UHF bands. The SAR features real-time image formation at fine resolution in spotlight and stripmap modes. High-quality images are formed in real time using the overlapped subaperture (OSA) image-formation and phase gradient autofocus (PGA) algorithms.

  18. Spin blockade and coherent dynamics of high-spin states in a three-electron double quantum dot

    Science.gov (United States)

    Chen, Bao-Bao; Wang, Bao-Chuan; Cao, Gang; Li, Hai-Ou; Xiao, Ming; Guo, Guang-Can; Jiang, Hong-Wen; Hu, Xuedong; Guo, Guo-Ping

    2017-01-01

    Asymmetry in a three-electron double quantum dot (DQD) allows spin blockade, when spin-3/2 (quadruplet) states and spin-1/2 (doublet) states have different charge configurations. We have observed this DQD spin blockade near the (1,2)-(2,1) charge transition using a pulsed-gate technique and a charge sensor. We, then, use this spin blockade to detect Landau-Zener-Stückelberg interference and coherent oscillations between the spin quadruplet and doublet states. Such studies add to our understandings of coherence and control properties of three-spin states in a double dot, which, in turn, would benefit explorations into various qubit encoding schemes in semiconductor nanostructures.

  19. Promising ferrimagnetic double perovskite oxides towards high spin polarization at high temperature

    Directory of Open Access Journals (Sweden)

    Si-Da Li

    2013-01-01

    Full Text Available We predict through our first-principles calculations that four double perovskite oxides of Bi2ABO6 (AB = FeMo, MnMo, MnOs, CrOs are half-metallic ferrimagnets. Our calculated results shows that the four optimized structures have negative formation energy, from -0.42 to -0.26 eV per formula unit, which implies that they could probably be realized. In the case of Bi2FeMoO6, the half-metallic gap and Curie temperature are predicted to reach to 0.71 eV and 650 K, respectively, which indicates that high spin polarization could be kept at high temperatures far beyond room temperature. It is believed that some of them could be synthesized soon and would prove useful for spintronic applications.

  20. Performance of high-resolution X-band radar for rainfall measurement in The Netherlands

    Directory of Open Access Journals (Sweden)

    C. Z. van de Beek

    2009-09-01

    Full Text Available This study presents an analysis of 195 rainfall events gathered with the X-band weather radar SOLIDAR and a tipping bucket rain gauge network near Delft, The Netherlands, between May 1993 and April 1994. The high spatial (120 m and temporal (16 s resolution of the radar combined with the extent of the database make this study a climatological analysis of the potential for high-resolution rainfall measurement with non-polarimetric X-band radar over completely flat terrain. An appropriate radar reflectivity – rain rate relation is derived from measurements of raindrop size distributions and compared with radar – rain gauge data. The radar calibration is assessed using a long-term comparison of rain gauge measurements with corresponding radar reflectivities as well as by analyzing the evolution of the stability of ground clutter areas over time. Three different methods for ground clutter correction as well as the effectiveness of forward and backward attenuation correction algorithms have been studied. Five individual rainfall events are discussed in detail to illustrate the strengths and weaknesses of high-resolution X-band radar and the effectiveness of the presented correction methods. X-band radar is found to be able to measure the space-time variation of rainfall at high resolution, far greater than can be achieved by rain gauge networks or a typical operational C-band weather radar. On the other hand, SOLIDAR can suffer from receiver saturation, wet radome attenuation as well as signal loss along the path. During very strong convective situations the signal can even be lost completely. In combination with several rain gauges for quality control, high resolution X-band radar is considered to be suitable for rainfall monitoring over relatively small (urban catchments. These results offer great prospects for the new high resolution polarimetric doppler X-band radar IDRA.

  1. Enhancement of M1 Transition Rates at High Spin in 90Mo

    Institute of Scientific and Technical Information of China (English)

    WU Xiao-Guang; YANG Chun-Xiang; LI Guang-Sheng; PENG Zhao-Hua; WEN Shu-Xian; HAN Guang-Bing; LI Cheng-Po; LU Shao-Jun; WU Shao-Yong; YUAN Guan-Jun

    2001-01-01

    High spin states in 90Mo have been populated through the 59Co (35C1,2p2n) 90Mo reaction at a beam energy of116 Me V. Level lifetimes of the positive-parity decay sequence are measured by using the Doppler shift attenuationmethod. It is observed that the M1 transition strengths show a substantial enhancement at high spin. Thisbehaviour may be related to occupation of high Ω orbitals by a pair of g9/2 protons. A deformed, oblate, shapeis suggested above the 13+ state.

  2. GW quasiparticle band gap of the hybrid organic-inorganic perovskite CH$_3$NH$_3$PbI$_3$: Effect of spin-orbit interaction, semicore electrons, and self-consistency

    OpenAIRE

    Filip, Marina R.; Giustino, Feliciano

    2014-01-01

    We study the quasiparticle band gap of the hybrid organic-inorganic lead halide perovskite CH$_3$NH$_3$PbI$_3$, using many-body perturbation theory based on the $GW$ approximation. We perform a systematic analysis of the band gap sensitivity to relativistic spin-orbit effects, to the description of semicore Pb-5$d$ and I-4$d$ electrons, and to the starting Kohn-Sham eigenvalues. We find that the inclusion of semicore states increases the calculated band gap by 0.2 eV, and self-consistency on ...

  3. High-κ TiO2 thin film prepared by sol-gel spin-coating method

    Science.gov (United States)

    Kumar, Arvind; Mondal, Sandip; Rao, K. S. R. Koteswara

    2015-06-01

    High-k TiO2 thin film on p-type silicon substrate was fabricated by a combined sol-gel and spin coating method. Thus deposited titania film had anatase phase with a small grain size of 16 nm and surface roughness of ≅ 0.6 nm. The oxide capacitance (Cox), flat band capacitance (CFB), flat band voltage (VFB), oxide trapped charge (Qot), calculated from the high frequency (1 MHz) C-V curve were 0.47 nF, 0.16 nF, - 0.91 V, 4.7x10-12 C, respectively. As compared to the previous reports, a high dielectric constant of 94 at 1 MHz frequency was observed in the devices investigated here and an equivalent oxide thickness (EOT) was 4.1 nm. Dispersion in accumulation capacitance shows a linear relationship with AC frequencies. Leakage current density was found in acceptable limits (2.1e-5 A/cm2 for -1 V and 5.7e-7 A/cm2 for +1 V) for CMOS applications.

  4. 旋转方形散射体对三角晶格磁振子晶体带结构的优化∗%Spin-wave band gaps created by rotating square ro ds in triangular lattice magnonic crystals

    Institute of Scientific and Technical Information of China (English)

    胡晓颖; 郭晓霞; 胡文弢; 呼和满都拉; 郑晓霞; 荆丽丽

    2015-01-01

    用改进的平面波展开法数值计算了正方形散射体三角排列的二维磁振子晶体当散射体旋转时的带结构。结果显示,同样的填充率下,旋转正方柱散射体可以在新的频率范围内打开更多的带隙,或者使低频带隙加宽。说明旋转散射体可以有效地优化带隙。%Recently, magnonic crystals which are the magnetic counterparts of photonic crystals or phononic crystals are becoming a hot area of research. In this paper, band structure of two-dimensional magnotic crystal composed of square rods triangularly arranged are calculated by using the plane-wave expansion method. Spin-wave band structures of two-dimensional magnonic crystal composed of Fe triangularly arranged Fe in an EuO matrix. The results show that when the filling ratio f =0.4, only two absolute band gaps can be found in the case of θ =0◦. The first gap appears between the first band and the second band, the second gap between the sixth band and the seventh band. However, the number of band gaps can be improved by rotating the square rods through θ =25◦, there are eight absolute band gaps that can be found. The first gap appears between the first band and the second band, the fifth gap between the sixth band and the seventh band. The new band gaps can be found, the second gap appears between the third band and the fourth band, the third gap between the fourth band and the fifth band, the fourth gap between the fifth band and the sixth band, the sixth gap between the seventh band and the eighth band, the seventh gap between the eighth band and the ninth band, the eighth gap between the ninth band and the tenth band. These results show that it is possible to create spin-wave gaps by rotating square rods in a two-dimensional magnotic crystal. The numerical results of the normalized gap width ∆Ω/Ωg of the first gap between the first band and the second band always changes with filling fraction f and rotational angles θ. When f

  5. A High Efficiency 1kWatt GaN Amplifier for P-Band Pulsed Applications Project

    Data.gov (United States)

    National Aeronautics and Space Administration — An improved efficiency amplifier for high power pulse applications at P-Band will be investigated that will support space based RADAR systems. Current P-Band pulsed...

  6. A High Efficiency 1kWatt GaN amplifier for P-Band pulsed applications Project

    Data.gov (United States)

    National Aeronautics and Space Administration — An improved efficiency amplifier for high power pulse applications at P-Band will be investigated that will support space based RADAR systems. Current P-Band pulsed...

  7. Femtosecond time-resolved optical and Raman spectroscopy of photoinduced spin crossover: temporal resolution of low-to-high spin optical switching.

    Science.gov (United States)

    Smeigh, Amanda L; Creelman, Mark; Mathies, Richard A; McCusker, James K

    2008-10-29

    A combination of femtosecond electronic absorption and stimulated Raman spectroscopies has been employed to determine the kinetics associated with low-spin to high-spin conversion following charge-transfer excitation of a FeII spin-crossover system in solution. A time constant of tau = 190 +/- 50 fs for the formation of the 5T2 ligand-field state was assigned based on the establishment of two isosbestic points in the ultraviolet in conjunction with changes in ligand stretching frequencies and Raman scattering amplitudes; additional dynamics observed in both the electronic and vibrational spectra further indicate that vibrational relaxation in the high-spin state occurs with a time constant of ca. 10 ps. The results set an important precedent for extremely rapid, formally forbidden (DeltaS = 2) nonradiative relaxation as well as defining the time scale for intramolecular optical switching between two electronic states possessing vastly different spectroscopic, geometric, and magnetic properties.

  8. High resolution x-ray fluorescence spectroscopy - a new technique for site- and spin-selectivity

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Xin [Univ. of California, Davis, CA (United States). Dept. of Applied Science

    1996-12-01

    X-ray spectroscopy has long been used to elucidate electronic and structural information of molecules. One of the weaknesses of x-ray absorption is its sensitivity to all of the atoms of a particular element in a sample. Through out this thesis, a new technique for enhancing the site- and spin-selectivity of the x-ray absorption has been developed. By high resolution fluorescence detection, the chemical sensitivity of K emission spectra can be used to identify oxidation and spin states; it can also be used to facilitate site-selective X-ray Absorption Near Edge Structure (XANES) and site-selective Extended X-ray Absorption Fine Structure (EXAFS). The spin polarization in K fluorescence could be used to generate spin selective XANES or spin-polarized EXAFS, which provides a new measure of the spin density, or the nature of magnetic neighboring atoms. Finally, dramatic line-sharpening effects by the combination of absorption and emission processes allow observation of structure that is normally unobservable. All these unique characters can enormously simplify a complex x-ray spectrum. Applications of this novel technique have generated information from various transition-metal model compounds to metalloproteins. The absorption and emission spectra by high resolution fluorescence detection are interdependent. The ligand field multiplet model has been used for the analysis of K{alpha} and K{beta} emission spectra. First demonstration on different chemical states of Fe compounds has shown the applicability of site selectivity and spin polarization. Different interatomic distances of the same element in different chemical forms have been detected using site-selective EXAFS.

  9. Crossover of high and low spin states in transition metal complexes

    CERN Document Server

    Raebiger, Hannes; Yasuhara, Hiroshi

    2012-01-01

    The stability of high vs. low spin states of transition metal complexes has been interpreted by ligand field theory, which is a perturbation theory of the electron-electron interaction. The present first principles calculation of a series of five cobalt complexes shows that the electron-electron interaction energy difference between the two states (i) exhibits the opposite trend to the total energy difference as the ligand nuclear charge varies, and (ii) is three or four orders of magnitude greater than the total energy difference. A new interpretation of the crossover of high and low spin states is given in terms of the chemical bonding.

  10. IBFA description of high-spin positive-parity states in Rh isotopes

    Science.gov (United States)

    Bucurescu, D.; Cǎta, G.; Cutoiu, D.; Constantinescu, G.; Ivascu, M.; Zamfir, N. V.

    1985-09-01

    Properties of the odd-mass Rh isotopes are investigated in the framework of the interacting boson-fermion approximation (IBFA) model in which the odd proton movea in the 1 g{9}/{2} and 2 d{5}/{2} orbitals. Lifetimes of some high-spin positive-parity states in 99Rh obtained by the recoil-distance method with the 88Sr( 14N, 3n) reaction are also reported. Calculated excitation energies and electromagnetic properties of the high-spin positive-parity states are compared with experiment and an acceptable agreement is obtained.

  11. IBFA description of high-spin positive-parity states in Rh isotopes

    Energy Technology Data Exchange (ETDEWEB)

    Bucurescu, D.; Cata, G.; Cutoiu, D.; Constantinescu, G.; Ivascu, M.; Zamfir, N.V.

    1985-09-30

    Properties of the odd-mass Rh isotopes are investigated in the framework of the interacting boson-fermion approximation (IBFA) model in which the odd proton moves in the 1gsub(9/2) and 2dsub(5/2) orbitals. Lifetimes of some high-spin positive-parity states in /sup 99/Rh obtained by the recoil-distance method with the /sup 88/Sr(/sup 14/N,3n) reaction are also reported. Calculated excitation energies and electromagnetic properties of the high-spin positive-parity states are compared with experiment and an acceptable agreement is obtained.

  12. An auto-balancer device for high spin-drying frequencies (LoWash Project)

    OpenAIRE

    Clerc Christian; Carbonelli Alexandre; Augez Romain

    2015-01-01

    Auto-balancing or active control balancing can be efficient solutions for high speed rotors with changing out-of-balance loads like washing machines in spin-drying mode. In the LoWash EU project, Vibratec is in charge to design, to build and to validate a balancing system for reducing the vibrations at high spin-drying speeds. The system is based on two trolleys rolling in a ring linked to the drum. The trolley shape allows a ring cross section optimization and they are equipped with a mechan...

  13. Active Microwave Technologies Using Ultra-High efficiency P-Band and L -Band Power Amplifiers Project

    Data.gov (United States)

    National Aeronautics and Space Administration — AlGaN/GaN devices on SiC substrates will be utilized to achieve Power Added Efficiencies (PAE) in excess of 85%. These wide band-gap solid-state semiconductors...

  14. High-Spin Isomeric States in Nuclear Reactions Induced by He Isotopes

    Science.gov (United States)

    Chuvilskaya, Tatjana; Shirokova, Alla

    2010-11-01

    The high-spin states production in nuclear reactions is reviewed. The analysis of various experiments, our estimates and calculations reveal that in different compound nucleus energy regions maximal relative yield of high-spin states can be realized by different projectiles: at low energies -- by neutrons, in ˜ 20 -- 50 MeV region -- by α-particles, at higher energies -- by heavy ions. It was predicted [1] that there are energy ranges in which neutron-rich radioactive ions (^6,8He, for example) are favorable. σm/σg (the ratio between the yields of high-spin Jm and low-spin Jg metastable states of a nucleus in one and the same reaction) e.g. the isomeric cross-section ratio is a very good indicator of high-spin states production capability of a nuclear reaction. These experiments demonstrate that maximal values of isomeric cross-section ratios (up to 30) are obtained in α-particle induced reactions. Experiment with ^6He beam [2] confirms the predictions of the work [1] concerning the prospects of neutron-rich radioactive-ion beams in high-spin states population. The results of calculations of the isomeric cross section ratios using the code EMPIRE-II-18 approach to statistical theory of nuclear reactions demonstrate rather good agreement with the experimental data. Due to that these prediction power of these calculation is confirmed. The results of widespread calculations of the isomeric cross-section ratios of the reactions with ^6,8He are presented. [1] T.V.Chvilskaya et al., AIP-Conference Proceedings ENAM-98 1998. V. 455. P. 482. [2] P.A.DeYoung et al., Phys.Rev.C. 2000. V. 62. P.047601.

  15. Rotor Design for High Pressure Magic Angle Spinning Nuclear Magnetic Resonance

    Energy Technology Data Exchange (ETDEWEB)

    Turcu, Romulus VF; Hoyt, David W.; Rosso, Kevin M.; Sears, Jesse A.; Loring, John S.; Felmy, Andrew R.; Hu, Jian Z.

    2013-01-01

    High pressure magic angle spinning (MAS) nuclear magnetic resonance (NMR) with a sample spinning rate exceeding 2.1 kHz and pressure greater than 165 bar has never been realized. In this work, a new sample cell design is reported, suitable for constructing cells of different sizes. Using a 7.5 mm high pressure MAS rotor as an example, internal pressure as high as 200 bar at a sample spinning rate of 6 kHz is achieved. The new high pressure MAS rotor is re-usable and compatible with most commercial NMR set-ups, exhibiting low 1H and 13C NMR background and offering maximal NMR sensitivity. As an example of its many possible applications, this new capability is applied to determine reaction products associated with the carbonation reaction of a natural mineral, antigorite ((Mg,Fe2+)3Si2O5(OH)4), in contact with liquid water in water-saturated supercritical CO2 (scCO2) at 150 bar and 50 deg C. This mineral is relevant to the deep geologic disposal of CO2, but its iron content results in too many sample spinning sidebands at low spinning rate. Hence, this chemical system is a good case study to demonstrate the utility of the higher sample spinning rates that can be achieved by our new rotor design. We expect this new capability will be useful for exploring solid-state, including interfacial, chemistry at new levels of high-pressure in a wide variety of fields.

  16. Rotor design for high pressure magic angle spinning nuclear magnetic resonance

    Science.gov (United States)

    Turcu, Romulus V. F.; Hoyt, David W.; Rosso, Kevin M.; Sears, Jesse A.; Loring, John S.; Felmy, Andrew R.; Hu, Jian Zhi

    2013-01-01

    High pressure magic angle spinning (MAS) nuclear magnetic resonance (NMR) with a sample spinning rate exceeding 2.1 kHz and pressure greater than 165 bar has never been realized. In this work, a new sample cell design is reported, suitable for constructing cells of different sizes. Using a 7.5 mm high pressure MAS rotor as an example, internal pressure as high as 200 bar at a sample spinning rate of 6 kHz is achieved. The new high pressure MAS rotor is re-usable and compatible with most commercial NMR set-ups, exhibiting low 1H and 13C NMR background and offering maximal NMR sensitivity. As an example of its many possible applications, this new capability is applied to determine reaction products associated with the carbonation reaction of a natural mineral, antigorite ((Mg,Fe2+)3Si2O5(OH)4), in contact with liquid water in water-saturated supercritical CO2 (scCO2) at 150 bar and 50 °C. This mineral is relevant to the deep geologic disposal of CO2, but its iron content results in too many sample spinning sidebands at low spinning rate. Hence, this chemical system is a good case study to demonstrate the utility of the higher sample spinning rates that can be achieved by our new rotor design. We expect this new capability will be useful for exploring solid-state, including interfacial, chemistry at new levels of high-pressure in a wide variety of fields.

  17. Data analysis of gravitational-wave signals from spinning neutron stars. V. A narrow-band all-sky search

    CERN Document Server

    Astone, Pia; Jaranowski, Piotr; Królak, Andrzej; Pietka, Maciej

    2010-01-01

    We present theory and algorithms to perform an all-sky coherent search for periodic signals of gravitational waves in narrow-band data of a detector. Our search is based on a statistic, commonly called the $\\mathcal{F}$-statistic, derived from the maximum-likelihood principle in Paper I of this series. We briefly review the response of a ground-based detector to the gravitational-wave signal from a rotating neuron star and the derivation of the $\\mathcal{F}$-statistic. We present several algorithms to calculate efficiently this statistic. In particular our algorithms are such that one can take advantage of the speed of fast Fourier transform (FFT) in calculation of the $\\mathcal{F}$-statistic. We construct a grid in the parameter space such that the nodes of the grid coincide with the Fourier frequencies. We present interpolation methods that approximately convert the two integrals in the $\\mathcal{F}$-statistic into Fourier transforms so that the FFT algorithm can be applied in their evaluation. We have impl...

  18. Magnetism and the spin state in cubic perovskite CaCo O3 synthesized under high pressure

    Science.gov (United States)

    Xia, Hailiang; Dai, Jianhong; Xu, Yuanji; Yin, Yunyu; Wang, Xiao; Liu, Zhehong; Liu, Min; McGuire, Michael A.; Li, Xiang; Li, Zongyao; Jin, Changqing; Yang, Yifeng; Zhou, Jianshi; Long, Youwen

    2017-07-01

    Cubic SrCo O3 with an intermediate spin state can only be stabilized by high pressure and high temperature (HPHT) treatment. It is metallic and ferromagnetic with the highest Curie temperature of the transition-metal perovskites. The chemical substitution by Ca on Sr sites would normally lower crystal symmetry from cubic to orthorhombic as seen in the perovskite family of Ca M O3 (M =M4 + of transition metals, G e4 + , S n4 + , and Z r4 + ) at room temperature. This structural change narrows the bandwidth, so as to further enhance the Curie temperature as the crossover to the localized electronic state is approached. We report a successful synthesis of the perovskite CaCo O3 with a HPHT treatment. Surprisingly, CaCo O3 crystallizes in a simple cubic structure that remains stable down to 20 K, the lowest temperature in the structural study. The new perovskite has been thoroughly characterized by a suite of measurements including transport, magnetization, specific heat, thermal conductivity, and thermoelectric power. Metallic CaCo O3 undergoes two successive magnetic transitions at 86 K and 54 K as temperature decreases. The magnetization at 5 K is compatible with the intermediate spin state t4e1 of C o4 + at the octahedral site. The thermal expansion of the Co-O bond length indicates that the population of high spin state t3e2 increases for T >100 K . The shortest Co-O bond length in cubic CaCo O3 is responsible for delocalizing electrons in the π*-band and itinerant-electron ferromagnetism at T <54 K . A comprehensive comparison between SrCo O3 and CaCo O3 and the justification of their physical properties by first-principles calculation have also been made in this report. Partially filled π* and σ* bands would make CaCo O3 suitable to study the Hund's coupling effect in a metal.

  19. NLTE Analysis of High Resolution H-band Spectra. I. Neutral Silicon

    CERN Document Server

    Zhang, Junbo; Pan, Kaike; Prieto, Carlos Allende; Liu, Chao

    2016-01-01

    We investigated the reliability of our silicon atomic model and the influence of non-local thermodynamical equilibrium (NLTE) on the formation of neutral silicon (Si I) lines in the near-infrared (near-IR) H-band. We derived the differential Si abundances for 13 sample stars with high-resolution H-band spectra from the Apache Point Observatory Galactic Evolution Experiment (APOGEE), as well as from optical spectra, both under local thermodynamical equilibrium (LTE) and NLTE conditions. We found that the differences between the Si abundances derived from the H-band and from optical lines for the same stars are less than 0.1 dex when the NLTE effects included, and that NLTE reduces the line-to-line scatter in the H-band spectra for most sample stars. These results suggest that our Si atomic model is appropriate for studying the formation of H-band Si lines. Our calculations show that the NLTE corrections of the Si I H-band lines are negative, i.e. the final Si abundances will be overestimated in LTE. The correc...

  20. High-fidelity transfer and storage of photon states in a single nuclear spin

    Science.gov (United States)

    Yang, Sen; Wang, Ya; Rao, D. D. Bhaktavatsala; Hien Tran, Thai; Momenzadeh, Ali S.; Markham, M.; Twitchen, D. J.; Wang, Ping; Yang, Wen; Stöhr, Rainer; Neumann, Philipp; Kosaka, Hideo; Wrachtrup, Jörg

    2016-08-01

    Long-distance quantum communication requires photons and quantum nodes that comprise qubits for interaction with light and good memory capabilities, as well as processing qubits for the storage and manipulation of photons. Owing to the unavoidable photon losses, robust quantum communication over lossy transmission channels requires quantum repeater networks. A necessary and highly demanding prerequisite for these networks is the existence of quantum memories with long coherence times to reliably store the incident photon states. Here we demonstrate the high-fidelity (˜98%) coherent transfer of a photon polarization state to a single solid-state nuclear spin that has a coherence time of over 10 s. The storage process is achieved by coherently transferring the polarization state of a photon to an entangled electron-nuclear spin state of a nitrogen-vacancy centre in diamond. The nuclear spin-based optical quantum memory demonstrated here paves the way towards an absorption-based quantum repeater network.

  1. Theoretical Design of High-spin Organic Molecules with Heterocycles as Ferromagnetic Coupling Units

    Institute of Scientific and Technical Information of China (English)

    WANG Li-min; ZHANG Jing-ping; WANG Rong-shun

    2003-01-01

    Novel stable high spin molecules possessing three different arranged fashions are designed with -*N-N< as a spin-containing(SC) fragment, phenylene as an end group and various aromatic molecules, such as benzene(1), 2,6-pyridine(2), 3,5-pyridine(3), pyridazine(4), 4,6-pyrimidine(5), 2,6-pyrimidine(6), pyrazine(7) and triazine(8), as a ferromagnetic coupling(FC) unit. The effects of the different coupling units on the spin multiplicities of the ground states and their stabilities were investigated by means of AM1-CI approach. It has been found that the spin densities on the two atoms of the SC fragment are different from delocalization results in the specific stability of -*N-N<. In these molecules, the stabilities of the triplet states decrease when the distance between the atoms of central SC(-N-) increases. It is shown that the heterocycles as the coupling units have influence on the stabilities of the high-spin ground states. That the heteroatom lying in m-phenyl can improve ferromagnetic coupling, while the heteroatom lying in o-phenyl or p-phenyl is not in favor of the ferromagnetic coupling.

  2. Effects of Spin on High-energy Radiation from Accreting Black Holes

    Science.gov (United States)

    O' Riordan, Michael; Pe'er, Asaf; McKinney, Jonathan C.

    2016-11-01

    Observations of jets in X-ray binaries show a correlation between radio power and black hole spin. This correlation, if confirmed, points toward the idea that relativistic jets may be powered by the rotational energy of black holes. In order to examine this further, we perform general relativistic radiative transport calculations on magnetically arrested accretion flows, which are known to produce powerful jets via the Blandford-Znajek (BZ) mechanism. We find that the X-ray and γ-ray emission strongly depend on spin and inclination angle. Surprisingly, the high-energy power does not show the same dependence on spin as the BZ jet power, but instead can be understood as a redshift effect. In particular, photons observed perpendicular to the spin axis suffer little net redshift until originating from close to the horizon. Such observers see deeper into the hot, dense, highly magnetized inner disk region. This effect is largest for rapidly rotating black holes due to a combination of frame dragging and decreasing horizon radius. While the X-ray emission is dominated by the near horizon region, the near-infrared (NIR) radiation originates at larger radii. Therefore, the ratio of X-ray to NIR power is an observational signature of black hole spin.

  3. Fabrication of highly aligned fibrous scaffolds for tissue regeneration by centrifugal spinning technology.

    Science.gov (United States)

    Loordhuswamy, Amalorpava Mary; Krishnaswamy, Venkat Raghavan; Korrapati, Purna Sai; Thinakaran, Senthilram; Rengaswami, Giri Dev Venkateshwarapuram

    2014-09-01

    Centrifugal spinning (C-Spin) is an emerging technology which uses centrifugal force to produce ultrafine fibers. Being a voltage free technique it can overcome the limitations of electrospinning. Owing to the unique characteristic features such as high surface area to volume ratio, porosity, mechanical strength and fiber alignment, centrifugal spun (C-spun) fibrous mat has a wide range of scope in various biomedical applications. Higher degree of fiber alignment can be effortlessly achieved by the C-Spin process. In order to prove the versatility of C-Spin system with respect to fiber alignment, Polycaprolactone (PCL) and gelatin were spun taking them as model polymers. The morphological analysis revealed that highly aligned ultrafine fibers with smooth surface are achieved by C-Spinning. Hydrophilicity, porosity and mechanical property results confirm that the C-spun mat is more suitable for tissue engineering applications. In vitro and in vivo experiments proved that the scaffolds are biocompatible and can be efficiently used as a wound dressing material.

  4. Flat-band voltage shift in metal-gate/high-k/Si stacks

    Institute of Scientific and Technical Information of China (English)

    Huang An-Ping; Zheng Xiao-Hu; Xiao Zhi-Song; Yang Zhi-Chao; Wang Mei; Paul K.Chu; Yang Xiao-Dong

    2011-01-01

    In metal-gate/high-k stacks adopted by the 45 nn technology node,the flat-band voltage (Vfb) shift remains one of the most critical challenges,particularly the flat-band voltage roll-off (Vfy roll-off) phenomenon in p-channel metaloxide-semiconductor (pMOS) devices with an ultrathin oxide layer. In this paper,recent progress on the investigation of the Vfb shift and the origin of the Vfb roll-off in the metal-gate/high-k pMOS stacks are reviewed. Methods that can alleviate the Vfb shift phenomenon are summarized and the future research trend is described.

  5. Band structure and phonon properties of lithium fluoride at high pressure

    Energy Technology Data Exchange (ETDEWEB)

    Panchal, J. M., E-mail: amitjignesh@yahoo.co.in [Government Engineering College, Gandhinagar 382028, Gujarat (India); Department of Physics, University School of Sciences, Gujarat University, Ahmedabad 380009, Gujarat (India); Joshi, Mitesh [Government Polytechnic for Girls, Athwagate, Surat395001, Gujarat (India); Gajjar, P. N., E-mail: pngajjar@rediffmail.com [Department of Physics, University School of Sciences, Gujarat University, Ahmedabad 380009, Gujarat (India)

    2016-05-23

    High pressure structural and electronic properties of Lithium Fluoride (LiF) have been studied by employing an ab-initio pseudopotential method and a linear response scheme within the density functional theory (DFT) in conjunction with quasi harmonic Debye model. The band structure and electronic density of states conforms that the LiF is stable and is having insulator behavior at ambient as well as at high pressure up to 1 Mbar. Conclusions based on Band structure, phonon dispersion and phonon density of states are outlined.

  6. Modeling the Multi-band Afterglow of GRB 130831A: Evidence for a Spinning-down Magnetar Dominated by Gravitational Wave Losses?

    Science.gov (United States)

    Zhang, Q.; Huang, Y. F.; Zong, H. S.

    2016-06-01

    The X-ray afterglow of GRB 130831A shows an “internal plateau” with a decay slope of ˜0.8, followed by a steep drop at around 105 s with a slope of ˜6. After the drop, the X-ray afterglow continues with a much shallower decay. The optical afterglow exhibits two segments of plateaus separated by a luminous optical flare, followed by a normal decay with a slope basically consistent with that of the late-time X-ray afterglow. The decay of the internal X-ray plateau is much steeper than what we expect in the simplest magnetar model. We propose a scenario in which the magnetar undergoes gravitational-wave-driven r-mode instability, and the spin-down is dominated by gravitational wave losses up to the end of the steep plateau, so that such a relatively steep plateau can be interpreted as the internal emission of the magnetar wind and the sharp drop can be produced when the magnetar collapses into a black hole. This scenario also predicts an initial X-ray plateau lasting for hundreds of seconds with an approximately constant flux which is compatible with observation. Assuming that the magnetar wind has a negligible contribution in the optical band, we interpret the optical afterglow as the forward shock emission by invoking the energy injection from a continuously refreshed shock following the prompt emission phase. It is shown that our model can basically describe the temporal evolution of the multi-band afterglow of GRB 130831A.

  7. A high-precision K-band LFMCW radar for range measurement

    Science.gov (United States)

    Jia, Yingzhuo; Chen, Xiuwei; Zou, Yongliao

    2016-11-01

    K-band LFMCW radar may be applied in high-precision range measurement, if its range resolution is made be close to mm magnitude, good performance is not only needed in hardware design, algorithm selection and optimization is but also needed. In K-band LFMCW radar system, CZT algorithm is modified according to practical radar echo signal, its simulation model is built in the System Generator tool software, the corresponding algorithm is implemented in FPGA. K-band LFMCW radar may be applied in range measurement of great volume storage tank, the outfield experiment was done according to application, experiment result shows that range measurement precision may reach mm magnitude, the system can meet the requirement of remote high-precision measurement.

  8. High-Q band edge mode of plasmonic crystals studied by cathodoluminescence

    Science.gov (United States)

    Honda, Masahiro; Yamamoto, Naoki

    2014-02-01

    We have investigated the quality factor (Q-factor) of the band edge modes in the plasmonic crystal by a cathodoluminescence technique. We have found that the Q-factor at the Γ point depends on the terrace width (D)/period (P) ratio of the plasmonic crystal. The finite-difference time-domain methods predict that the band edge mode at D/P = 3/4 has a high-Q-factor (Q ˜ 250 by Palik's permittivity data and Q ˜ 530 by Johnson and Christy's data). The beam-scan spectral images allowed us to visualize the standing surface plasmon polariton waves at the band edge energies, and a high-Q-factor of ˜200 was observed at D/P ˜ 3/4.

  9. High-Q band edge mode of plasmonic crystals studied by cathodoluminescence

    Energy Technology Data Exchange (ETDEWEB)

    Honda, Masahiro; Yamamoto, Naoki, E-mail: nyamamot@phys.titech.ac.jp [Department of Physics, Tokyo Institute of Technology, Tokyo 152-8551 (Japan)

    2014-02-24

    We have investigated the quality factor (Q-factor) of the band edge modes in the plasmonic crystal by a cathodoluminescence technique. We have found that the Q-factor at the Γ point depends on the terrace width (D)/period (P) ratio of the plasmonic crystal. The finite-difference time-domain methods predict that the band edge mode at D/P = 3/4 has a high-Q-factor (Q ∼ 250 by Palik's permittivity data and Q ∼ 530 by Johnson and Christy's data). The beam-scan spectral images allowed us to visualize the standing surface plasmon polariton waves at the band edge energies, and a high-Q-factor of ∼200 was observed at D/P ∼ 3/4.

  10. Design of high gradient, high repetition rate damped C -band rf structures

    Science.gov (United States)

    Alesini, David; Bellaveglia, Marco; Bini, Simone; Gallo, Alessandro; Lollo, Valerio; Pellegrino, Luigi; Piersanti, Luca; Cardelli, Fabio; Migliorati, Mauro; Mostacci, Andrea; Palumbo, Luigi; Tocci, Simone; Ficcadenti, Luca; Pettinacci, Valerio

    2017-03-01

    The gamma beam system of the European Extreme Light Infrastructure-Nuclear Physics project foresees the use of a multibunch train colliding with a high intensity recirculated laser pulse. The linac energy booster is composed of 12 traveling wave C -band structures, 1.8 m long with a field phase advance per cell of 2 π /3 and a repetition rate of 100 Hz. Because of the multibunch operation, the structures have been designed with a dipole higher order mode (HOM) damping system to avoid beam breakup (BBU). They are quasiconstant gradient structures with symmetric input couplers and a very effective damping of the HOMs in each cell based on silicon carbide (SiC) rf absorbers coupled to each cell through waveguides. An optimization of the electromagnetic and mechanical design has been done to simplify the fabrication and to reduce the cost of the structures. In the paper, after a review of the beam dynamics issues related to the BBU effects, we discuss the electromagnetic and thermomechanic design criteria of the structures. We also illustrate the criteria to compensate the beam loading and the rf measurements that show the effectiveness of the HOM damping.

  11. Results from EDGES High-band. I. Constraints on Phenomenological Models for the Global 21 cm Signal

    Science.gov (United States)

    Monsalve, Raul A.; Rogers, Alan E. E.; Bowman, Judd D.; Mozdzen, Thomas J.

    2017-09-01

    We report constraints on the global 21 cm signal due to neutral hydrogen at redshifts 14.8≥slant z≥slant 6.5. We derive our constraints from low-foreground observations of the average sky brightness spectrum conducted with the EDGES High-band instrument between 2015 September 7 and October 26. Observations were calibrated by accounting for the effects of antenna beam chromaticity, antenna and ground losses, signal reflections, and receiver parameters. We evaluate the consistency between the spectrum and phenomenological models for the global 21 cm signal. For tanh-based representations of the ionization history during the epoch of reionization, we rule out, at ≥slant 2σ significance, models with duration of up to {{Δ }}z=1 at z≈ 8.5 and higher than {{Δ }}z=0.4 across most of the observed redshift range under the usual assumption that the 21 cm spin temperature is much larger than the temperature of the cosmic microwave background during reionization. We also investigate a “cold” intergalactic medium (IGM) scenario that assumes perfect Lyα coupling of the 21 cm spin temperature to the temperature of the IGM, but that the latter is not heated by early stars or stellar remants. Under this assumption, we reject tanh-based reionization models of duration {{Δ }}z≲ 2 over most of the observed redshift range. Finally, we explore and reject a broad range of Gaussian models for the 21 cm absorption feature expected in the First Light era. As an example, we reject 100 mK Gaussians with duration (full width at half maximum) {{Δ }}z≤slant 4 over the range 14.2≥slant z≥slant 6.5 at ≥slant 2σ significance.

  12. NLTE Analysis of High Resolution H-band Spectra. II. Neutral Magnesium

    CERN Document Server

    Zhang, Junbo; Pan, Kaike; Prieto, Carlos Allende; Liu, Chao

    2016-01-01

    Aiming at testing the validity of our magnesium atomic model and investigating the effects of non-local thermodynamical equilibrium (NLTE) on the formation of the H-band neutral magnesium lines, we derive the differential Mg abundances from selected transitions for 13 stars either adopting or relaxing the assumption of local thermodynamical equilibrium (LTE). Our analysis is based on high-resolution and high signal-to-noise ratio H-band spectra from the Apache Point Observatory Galactic Evolution Experiment (APOGEE) and optical spectra from several instruments. The absolute differences between the Mg abundances derived from the two wavelength bands are always less than 0.1 dex in the NLTE analysis, while they are slightly larger for the LTE case. This suggests that our Mg atomic model is appropriate for investigating the NLTE formation of the H-band Mg lines. The NLTE corrections for the Mg I H-band lines are sensitive to the surface gravity, becoming larger for smaller log g values, and strong lines are more...

  13. X-Ray Absorption Spectroscopic Studies of High-Spin Nonheme (Alkylperoxo)Iron(III) Intermediates

    Energy Technology Data Exchange (ETDEWEB)

    Shan, X.; Rohde, J.-U.; Koehntop, K.D.; Zhou, Y.; Bukowski, M.R.; Costas, M.; Fujisawa, K.; Que, L.; Jr.

    2009-06-04

    The reactions of iron(II) complexes [Fe(Tp{sup t-Bu,i-Pr})(OH)] (1a, Tp{sup t-Bu,i-Pr} = hydrotris(3-tert-butyl-5-isopropyl-1-pyrazolyl)borate), [Fe(6-Me{sub 2}BPMCN)(OTf){sub 2}] (1b, 6-Me{sub 2}BPMCN = N,N'-bis((2-methylpyridin-6-yl)methyl)-N,N'-dimethyl-trans-1,2-diaminocyclohexane), and [Fe(L{sup 8}Py{sub 2})(OTf)](OTf) (1c, L{sup 8}Py{sub 2} = 1,5-bis(pyridin-2-ylmethyl)-1,5-diazacyclooctane) with tert-BuOOH give rise to high-spin Fe{sup III}-OOR complexes. X-ray absorption spectra (XAS) of these high-spin species show characteristic features, distinct from those of low-spin Fe-OOR complexes (Rohde, J.-U.; et al. J. Am. Chem. Soc. 2004, 126, 16750--16761). These include (1) an intense 1s {yields} 3d preedge feature, with an area around 20 units, (2) an edge energy, ranging from 7122 to 7126 eV, that is affected by the coordination environment, and (3) a 1.86--1.96 {angstrom} Fe-OOR bond, compared to the 1.78 {angstrom} Fe-OOR bond in low-spin complexes. These unique features likely arise from a flexible first coordination sphere in those complexes. The difference in Fe-OOR bond length may rationalize differences in reactivity between low-spin and high-spin Fe{sup III}-OOR species.

  14. Universality, maximum radiation, and absorption in high-energy collisions of black holes with spin.

    Science.gov (United States)

    Sperhake, Ulrich; Berti, Emanuele; Cardoso, Vitor; Pretorius, Frans

    2013-07-26

    We explore the impact of black hole spins on the dynamics of high-energy black hole collisions. We report results from numerical simulations with γ factors up to 2.49 and dimensionless spin parameter χ=+0.85, +0.6, 0, -0.6, -0.85. We find that the scattering threshold becomes independent of spin at large center-of-mass energies, confirming previous conjectures that structure does not matter in ultrarelativistic collisions. It has further been argued that in this limit all of the kinetic energy of the system may be radiated by fine tuning the impact parameter to threshold. On the contrary, we find that only about 60% of the kinetic energy is radiated for γ=2.49. By monitoring apparent horizons before and after scattering events we show that the "missing energy" is absorbed by the individual black holes in the encounter, and moreover the individual black-hole spins change significantly. We support this conclusion with perturbative calculations. An extrapolation of our results to the limit γ→∞ suggests that about half of the center-of-mass energy of the system can be emitted in gravitational radiation, while the rest must be converted into rest-mass and spin energy.

  15. Spin-polarized high-energy scattering of charged leptons on nucleons

    Energy Technology Data Exchange (ETDEWEB)

    Burkardt, M. [New Mexico State Univ., Las Cruces, NM (United States). Dept. of Physics; Miller, C.A. [TRIUMF, Vancouver, BC (Canada); Nowak, W.D. [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany)

    2009-08-15

    The proton is a composite object with spin one-half, understood to contain highly relativistic spin one-half quarks exchanging spin-one gluons, each possibly with significant orbital angular momenta. While their fundamental interactions are well described by Quantum ChromoDynamics (QCD), our standard theory of the strong interaction, nonperturbative calculations of the internal structure of the proton based directly on QCD are beginning to provide reliable results. Most of our present knowledge of the structure of the proton is based on experimental measurements interpreted within the rich framework of QCD. An area presently attracting intense interest, both experimental and theoretical, is the relationship between the spin of the proton and the spins and orbital angular momenta of its constituents. While remarkable progress has been made, especially in the last decade, the discovery and investigation of new concepts have revealed that much more remains to be learned. This progress is reviewed and an outlook for the future is offered. (orig.)

  16. High-Fidelity Microwave Control of Single-Atom Spin Qubits in Silicon

    Science.gov (United States)

    2014-07-08

    systems, the value of a bit is obtained by measuring a low-voltage (0) or high-voltage (1) at the terminals of a transistor. In order to measure our...time TH2 . In bulk experiments, this measurement is realised by detecting the magnetisation of the spins after the πx pulse. Magnetisation will be...current values for the separate states N↑ and N↓ (see Figure 2.10b). From these we can extract the electrical fidelity in measuring a spin-up (Fe

  17. Excitation Spectrum of Spin-1 Bosonic Atoms in an Optical Lattice with High Filling Factors

    Institute of Scientific and Technical Information of China (English)

    HOU Jing-Min

    2007-01-01

    The Green's function and the higher-order correlation functions of spin-1 cold atoms in an optical lattice are defined.Because we consider the problem of spin-1 Bose condensed atoms in an optical lattice with high filling factors,I.e.,the number density of Bose condensed atoms no is large,the fluctuation of them can be neglected and we take mean-field approximation for the higher-order terms.The excitation spectra for both the polar case and the ferromagnetic case are obtained and analyzed.

  18. Ka-Band TWT High-Efficiency Power Combiner for High-Rate Data Transmission

    Science.gov (United States)

    Wintucky, Edwin G.; Simons, Rainee; Vaden, Karl R.; Lesny, Gary G.; Glass, Jeffrey L.

    2007-01-01

    A four-port magic-T hybrid waveguide junction serves as the central component of a high-efficiency two-way power combiner circuit for transmitting a high-rate phase-modulated digital signal at a carrier frequency in the Ka-band (between 27 and 40 GHz). This power combiner was developed to satisfy a specific requirement to efficiently combine the coherent outputs of two traveling-wavetube (TWT) amplifiers that are typically characterized by power levels on the order of 100 W or more. In this application, the use of a waveguide-based power combiner (instead of a coaxial-cable- or microstrip-based power combiner, for example) is dictated by requirements for low loss, high power-handling capability, and broadband response. Combiner efficiencies were typically 90 percent or more over both the linear and saturated output power regions of operation of the TWTs . Figure 1 depicts the basic configuration of the magic-T hybrid junction. The coherent outputs of the two TWTs enter through ports 1 and 4. As a result of the orientations of the electromagnetic fields, which also provides a needed high port-to-port isolation, of these two input signals and the interior design of the magic-T junction, the input powers are divided so as to add in phase at one output port (port 2), and to be opposite in phase and hence cancel each other at the opposite coplanar output port (port 3). The net result is that the output power at port 2 is essentially double that of the output of one TWT, minus the power lost in the magic-T hybrid junction. Optimum performance as a high-efficiency power combiner thus requires a balance of both power and phase at the input ports of the magic-T. Replicas of this two-way combiner can be arranged in a binary configuration to obtain a 2n-way (where n is an integer) combiner. For example, Figure 2 illustrates the use of three two-way combiners to combine the outputs of four TWTs.

  19. High precision beam momentum determination in a synchrotron using a spin resonance method

    CERN Document Server

    Goslawski, P; Gebel, R; Hartmann, M; Kacharava, A; Lehrach, A; Lorentz, B; Maier, R; Mielke, M; Papenbrock, M; Prasuhn, D; Stassen, R; Stein, H J; Stockhorst, H; Ströher, H; Wilkin, C

    2009-01-01

    In order to measure the mass of the eta meson with high accuracy using the d+p -> 3He+eta reaction, the momentum of the circulating deuteron beam in the Cooler Synchrotron COSY of the Forschungszentrum Juelich has to be determined with unprecedented precision. This has been achieved by studying the spin dynamics of the polarized deuteron beam. By depolarizing the beam through the use of an artificially induced spin resonance, it was possible to evaluate its momentum p with a precision of dp/p < 10-4 for a momentum of roughly 3 GeV/c. Different possible sources of error in the application of the spin resonance method are discussed in detail and its possible use during a standard experiment is considered.

  20. Spin polarization in high density quark matter under a strong external magnetic field

    CERN Document Server

    Tsue, Yasuhiko; Providencia, Constanca; Yamamura, Masatoshi; Bohr, Henrik

    2016-01-01

    In high density quark matter under a strong external magnetic field, possible phases are investigated by using the Nambu-Jona-Lasinio model with axial vector-type four-point interaction or tensor-type four-point interaction between quarks. In the axial vector-type interaction, it is shown that a quark spin polarized phase is realized in all region of the quark chemical potential under a strong external magnetic field within the lowest Landau level approximation. Each phase is characterized by the chiral condensate or dynamical quark mass. On the other hand, in the tensor-type interaction, it is also shown that the quark spin polarized phase does not appear even if there exists the strong external magnetic field. However, if the anomalous magnetic moment of quark is taken into account, it may be possible to realize the quark spin polarized phase.

  1. High spin polarization in CoFeMnGe equiatomic quaternary Heusler alloy

    Energy Technology Data Exchange (ETDEWEB)

    Bainsla, Lakhan [Department of Physics, Indian Institute of Technology Bombay, Mumbai 400076 (India); Magnetic Materials Unit, National Institute for Materials Science, Tsukuba 305-0047 (Japan); Suresh, K. G., E-mail: suresh@phy.iitb.ac.in [Department of Physics, Indian Institute of Technology Bombay, Mumbai 400076 (India); Nigam, A. K. [Department of Condensed Matter and Materials Science, Tata Institute of Fundamental Research, Mumbai 400005 (India); Manivel Raja, M. [Defence Metallurgical Research Laboratory, Hyderabad 500058 (India); Varaprasad, B. S. D. Ch. S.; Takahashi, Y. K.; Hono, K. [Magnetic Materials Unit, National Institute for Materials Science, Tsukuba 305-0047 (Japan)

    2014-11-28

    We report the structure, magnetic property, and spin polarization of CoFeMnGe equiatomic quaternary Heusler alloy. The alloy was found to crystallize in the cubic Heusler structure (prototype LiMgPdSn) with considerable amount of DO{sub 3} disorder. Thermal analysis result indicated the Curie temperature is about 750 K without any other phase transformation up to melting temperature. The magnetization value was close to that predicted by the Slater-Pauling curve. Current spin polarization of P = 0.70 ± 0.01 was deduced using point contact andreev reflection measurements. The temperature dependence of electrical resistivity has been fitted in the temperature range of 5–300 K in order to check for the half metallic behavior. Considering the high spin polarization and Curie temperature, this material appears to be promising for spintronic applications.

  2. Wild Band Edges: The Role of Bandgap Grading and Band-Edge Fluctuations in High-Efficiency Chalcogenide Devices: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Repins, Ingrid; Mansfield, Lorelle; Kanevce, Ana; Jensen, Soren A.; Kuciauskas, Darius; Glynn, Stephen; Barnes, Teresa; Metzger, Wyatt; Burst, James; Jiang, Chun-Sheng; Dippo, Patricia; Harvey, Steve; Teeter, Glenn; Perkins, Craig; Egaas, Brian; Zakutayev, Andriy; Alsmeier, J.-H.; Lussky, T.; Korte, L.; Wilks, R. G.; Bar, M.; Yan, Y.; Lany, Stephan; Zawadzki, Pawel; Park, Ji-Sang; Wei, Suhuai

    2016-06-16

    Band-edge effects -- including grading, electrostatic fluctuations, bandgap fluctuations, and band tails -- affect chalcogenide device efficiency. These effects now require more careful consideration as efficiencies increase beyond 20%. Several aspects of the relationships between band-edge phenomena and device performance for NREL absorbers are examined. For Cu(In,Ga)Se2 devices, recent increases in diffusion length imply changes to optimum bandgap profile. The origin, impact, and modification of electrostatic and bandgap fluctuations are also discussed. The application of the same principles to devices based on CdTe, kesterites, and emerging absorbers (Cu2SnS3, CuSbS2), considering differences in materials properties and defect formation energies, is examined.

  3. Wild Band Edges: The Role of Bandgap Grading and Band-Edge Fluctuations in High-Efficiency Chalcogenide Devices

    Energy Technology Data Exchange (ETDEWEB)

    Repins, Ingrid; Mansfield, Lorelle; Kanevce, Ana; Jensen, Soren A.; Kuciauskas, Darius; Glynn, Stephen; Barnes, Teresa; Metzger, Wyatt; Burst, James; Jiang, Chun-Sheng; Dippo, Patricia; Harvey, Steve; Teeter, Glenn; Perkins, Craig; Egaas, Brian; Zakutayev, Andriy; Alsmeier, J.-H.; Lussky, T.; Korte, L.; Wilks, R. G.; Bar, M.; Yan, Y.; Lany, Stephan; Zawadzki, Pawel; Park, Ji-Sang; Wei, Suhuai

    2016-11-21

    Band-edge effects - including grading, electrostatic fluctuations, bandgap fluctuations, and band tails - affect chalcogenide device efficiency. These effects now require more careful consideration as efficiencies increase beyond 20%. Several aspects of the relationships between band-edge phenomena and device performance for NREL absorbers are examined. For Cu(In, Ga)Se2 devices, recent increases in diffusion length imply changes to the optimum bandgap profile. The origin, impact, and modification of electrostatic and bandgap fluctuations are also discussed. The application of the same principles to devices based on CdTe, kesterites, and emerging absorbers (Cu2SnS3, CuSbS2), considering differences in materials properties, is examined.

  4. Site-specific spin crossover in F e2Ti O4 post-spinel under high pressure up to nearly a megabar

    Science.gov (United States)

    Xu, W. M.; Hearne, G. R.; Layek, S.; Levy, D.; Itié, J.-P.; Pasternak, M. P.; Rozenberg, G. Kh.; Greenberg, E.

    2017-07-01

    X-ray diffraction studies to ˜90 GPa at room temperature show that F e2Ti O4 ferrous inverse spinel undergoes the following sequence of structural transitions: cubic (F d 3 ¯m ) →˜8 GPa tetragonal (I 41/a m d ) →˜16 GPa orthorhombic (C m c m ) →˜55 GPa orthorhombic (P m m a ) , at the indicated onset transition pressures. Within the Cmcm phase, site-specific spin crossover is initiated and involves only highly distorted octahedral sites constituting ˜25 % of all Fe locations. This is manifest as a steeper volume decrease of Δ V /V0˜3.5 % beyond ˜40 GPa and an emergent diamagnetic component discerned in 57Fe Mössbauer spectroscopy at variable cryogenic temperatures. A subsequent C m c m →P m m a Fe/Ti disorder-order reconfiguration is facilitated at sixfold coordinated (octahedral) sites. The rest of the high-spin Fe in sixfold and eightfold coordinated sites (˜75 % abundance) in the Pmma phase exhibit average saturation internal magnetic fields of Hh f˜42 T to ˜90 GPa , typical of spin-only (orbitally quenched) Fermi-contact values. By contrast, average Hh f˜20 T values, signifying unquenched orbital moments, occur below the 40 -45 GPa spin-crossover initiation regime in the Cmcm phase. Therefore, site-specific spin crossover invokes a cooperative lattice response and polyhedral distortions at the rest of the high-spin Fe sites, translating to 3 d level (sub-band) changes and consequential orbital moment quenching. Near ˜90 GPa , F e2Ti O4 is a partially spin-converted chemically ordered Pmma post-spinel having a persistent charge gap of ˜100 meV . Despite structural symmetry changes, partial spin crossover and lattice compressibility, resulting in a ˜33 % total reduction in unit-cell volume and corresponding 3 d bandwidth broadening, strong electron correlations persist at high densification.

  5. Synchrotron-based rotationally resolved high-resolution FTIR spectroscopy of azulene and the unidentified infrared bands of astronomy.

    Science.gov (United States)

    Albert, Sieghard; Lerch, Philippe; Quack, Martin

    2013-10-07

    Chasing the unidentified IR bands: The first rotationally resolved high-resolution infrared spectrum of azulene is reported using synchrotron Fourier transform infrared spectroscopy including a rovibrational analysis of the out-of-plane fundamental ν44. Comparison of azulene, naphthalene, indole, and biphenyl infrared bands leads to coincidences with UIR bands at 12.8 μm with naphthalene and at 13.55 and 14.6 μm with biphenyl bands, but excluding azulene as a strong absorber.

  6. Spin polarization versus color–flavor locking in high-density quark matter

    DEFF Research Database (Denmark)

    Tsue, Yasuhiko; da Providência, João; Providência, Constança;

    2015-01-01

    It is shown that spin polarization with respect to each flavor in three-flavor quark matter occurs instead of color–flavor locking at high baryon density by using the Nambu–Jona-Lasinio model with four-point tensor-type interaction. Also, it is indicated that the order of phase transition between...

  7. Effect of high-frequency excitation on natural frequencies of spinning discs

    DEFF Research Database (Denmark)

    Hansen, Morten Hartvig

    2000-01-01

    The effect of high-frequency, non-resonant parametric excitation on the low-frequency response of spinning discs is considered. The parametric excitation is obtained through a non-constant rotation speed, where the frequency of the pulsating overlay is much higher than the lowest natural frequenc...

  8. Preliminary experimental investigation of a complex dual-band high power microwave source

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Xiaoping, E-mail: zhangxiaoping@nudt.edu.cn; Li, Yangmei; Li, Zhiqiang; Zhong, Huihuang; Qian, Baoliang [College of Optoelectronic Science and Engineering, National University of Defense Technology, Changsha 410073 (China)

    2015-10-15

    In order to promote the power conversion efficiency of a magnetically insulated transmission line oscillator (MILO) and obtain microwaves in dual bands, an axially extracted C-band virtual cathode oscillator (VCO) with multiple resonant cavities is introduced to partially utilize the load current of an S-band MILO. The formed novel dual-band high power microwave source called MILO and VCO is investigated with simulation and experimentally. A dual-band radiation antenna is designed to effectively radiate microwaves generated by the MILO and the VCO, respectively, while avoiding them being influenced by the microwave reflection and diffraction. The preliminary experimental results measured by the dual-band diagnostic system show that both the MILO and the VCO operate normally under repeated shots. A microwave of 2.1 GHz, 1.70 GW is generated from the MILO and a 0.37 GW microwave at frequencies of 4.1 GHz and 3.8 GHz is generated from the VCO under the condition of about 440 kV and 35 kA. Compared with a single MILO (10.6%), a MILO and VCO achieves higher total power and efficiency (13.4%) in both S and C bands, indicating that the load current of the MILO partially couples into the beam-wave interaction in the VCO and then contributes to the output microwaves. However, more works are needed regarding the spectrum purification of the VCO and promotion of the output power of both the MILO and the VCO.

  9. Compact printed high rejection triple band-notch UWB antenna with multiple wireless applications

    Directory of Open Access Journals (Sweden)

    Manish Sharma

    2016-09-01

    Full Text Available In this paper, small printed urn-shape triple notch ultra-wideband (UWB monopole antenna with diverse wireless applications is presented. Notch bands include WiMAX (IEEE802.16 3.30–3.80 GHz, WLAN IEEE802.11a/h/j/n (5.15–5.35 GHz, 5.25–5.35 GHz, 5.47–5.725 GHz, 5.725–5.825 GHz, and X-band downlink satellite system (7.25–7.75 GHz and other multiple wireless services as close range radar (8–12 GHz in X-band & satellite communication (12–18 GHz in Ku-band. By including T-shape stub and etching two C-shaped slots on the radiating patch, triple band-notch function is obtained with measured high band rejection (VSWR = 16.54 at 3.60 GHz, VSWR = 22.35 at 5.64 GHz and VSWR = 6.38 at 7.64 GHz and covers a wide useable fractional bandwidth of 154.56% (2.49–19.41 GHz. In short the antenna offers triple band-notch UWB systems as a compact multifunctional antenna to reduce the number of antennas installed in wireless devices for accessing multiple wireless networks with wide radiation pattern.

  10. Performance of high-resolution X-band radar for rainfall measurement in the Netherlands

    NARCIS (Netherlands)

    Beek, van de C.Z.; Leijnsel, H.; Stricker, J.N.M.; Uijlenhoet, R.; Russchenberg, H.W.J.

    2010-01-01

    This study presents an analysis of 195 rainfall events gathered with the X-band weather radar SOLIDAR and a tipping bucket rain gauge network near Delft, The Netherlands, between May 1993 and April 1994. The aim of this paper is to present a thorough analysis of a climatological dataset using a high

  11. Performance of high-resolution X-band radar for rainfall measurement in The Netherlands

    NARCIS (Netherlands)

    Van de Beek, C.Z.; Leijnse, H.; Stricker, J.N.M.; Uijlenhoet, R.; Russchenberg, H.W.J.

    2010-01-01

    This study presents an analysis of 195 rainfall events gathered with the X-band weather radar SOLIDAR and a tipping bucket rain gauge network near Delft, The Netherlands, between May 1993 and April 1994. The aim of this paper is to present a thorough analysis of a climatological dataset using a high

  12. The K Band Luminosity Functions of Galaxies in High Redshift Clusters

    CERN Document Server

    Ellis, S C

    2004-01-01

    K band luminosity functions (LFs) of three, massive, high redshift clusters of galaxies are presented. The evolution of K*, the characteristic magnitude of the LF, is consistent with purely passive evolution, and a redshift of forma tion z = 1.5-2.

  13. The Effectiveness of a Unit Study-Technology Approach within the High School Band Rehearsal Setting

    Science.gov (United States)

    Gustafson-Hinds, Melissa A.

    2010-01-01

    The purpose of this research study was to investigate the usefulness of implementing a Comprehensive Musicianship (CMP)--Unit Study within a high school band rehearsal setting, using music technology as a supplementary tool. While previous studies have emphasized the many benefits of Comprehensive Musicianship, it is not clear how such an approach…

  14. Probe-Fed Stacked Microstrip Patch Antenna for High-Resolution Polarimetric C-Band SAR

    DEFF Research Database (Denmark)

    Granholm, Johan; Skou, Niels

    2000-01-01

    The paper describes a C-band, dual-linear polarization wideband antenna for use in the next-generation of the Danish high-resolution, airborne polarimetric synthetic aperture radar (SAR) system, EMISAR. The design and performance of a probe-fed, stacked microstrip patch element, operating from 4...

  15. EDITORIAL: New materials with high spin polarization: half-metallic Heusler compounds

    Science.gov (United States)

    Felser, Claudia; Hillebrands, Burkard

    2007-03-01

    , with emphasis on new rational design of Heusler compounds and advanced characterization tools. This volume of Journal of Physics D: Applied Physics summarizes the latest research results obtained in the Research Unit and presents it to the scientific public as a cluster of refereed papers. Half-metallic ferromagnets are an impressive example for the rational design of new materials based on computational physics. The paper of Kandpal et al demonstrates how a detailed understanding of the electronic structure, especially from the viewpoint of the properties of the minority band gap and the peculiar magnetic behaviour, enables us to predict new half-metallic compounds. A high interface quality and a well ordered compound are the preconditions to realize the predicted half-metallic properties. Wurmehl et al have carefully studied the surface and bulk structure of the classical Heusler compound CCFA using a combination of characterization methods. A deposition process of epitaxial thin films of CCFA was described by Conca et al. Kallmayer et al have correlated the structural properties of thin magnetron sputtered films determined by x-ray diffraction with details of the x-ray magnetic circular dichroism (XMCD) spectra. From the value of the magnetic moment located at the Cr atom and features of the Co absorption spectra, they conclude that the buffer layers lead to an improvement of local atomic order. A highlight of this Cluster Issue is the spin resolved photoemission result of Cinchetti and co-workers. A careful in situ preparation of the sample surface of CCFA leads to values for the room temperature spin polarization up to 45% at the Fermi level, the highest value measured so far at the surface region of a full Heusler compound at room temperature. Co2FeSi (CFS) is the half-metal Heusler compound with the highest Curie temperature reported so far [4]. Schneider et al report the deposition of well ordered thin Co2FeSi films by RF magnetron sputtering. The thickness

  16. Empirical determination of the energy band gap narrowing in highly doped n+ silicon

    Science.gov (United States)

    Yan, Di; Cuevas, Andres

    2013-07-01

    Highly doped regions in silicon devices should be analyzed using Fermi-Dirac statistics, taking into account energy band gap narrowing (BGN). An empirical expression for the BGN as a function of dopant concentration is derived here by matching the modeled and measured thermal recombination current densities J0 of a broad range of n+ dopant concentration profiles prepared by phosphorus diffusion. The analysis is repeated with Boltzmann statistics in order to determine a second empirical expression for the apparent energy band gap narrowing, which is found to be in good agreement with previous work.

  17. Assessment of bird populations in a high quality savanna/woodland: a banding approach

    Science.gov (United States)

    Wilmore, Sandra L.; Glowacki, Gary A.; Grundel, Ralph

    2005-01-01

    Between 1999 and 2004, Save the Dunes Conservation Fund's Miller Woods Bird Banding Program monitored migrating and breeding bird populations within a high quality black oak, dry-mesic sand savanna/woodland with ridge and swale topography. The objectives of this program were to collect consistent and reliable demographic and abundance data on the bird populations, to investigate long-term population trends, and to contribute to improved land management decisions at regional and national scales. The technique employed involved capturing birds in mist nets that were deployed for set periods of time at 17 net sites in two banding areas in Miller Woods.

  18. High capacity hybrid optical fiber-wireless links in 75–300GHz band

    DEFF Research Database (Denmark)

    Cavalcante, Lucas Costa Pereira; Vegas Olmos, Juan José; Tafur Monroy, Idelfonso

    2014-01-01

    , is seeding the need to use bands located at the millimeter-wave region (30–300 GHz), mainly because of its inherent broadband nature. In our lab, we have conducted extensive research on high-speed photonic-wireless links in the W-band (75–110GHz). In this paper, we will present our latest findings...... and experimental results on the specific 81–86GHz sub-band. These include photonic generation of millimeter-wave carriers and transmission performance of broadband signals on different types of fibers and span lengths. We will also present our current work, where we propose an analysis framework that offers...... a multidimensional view of crucial parameters for millimeter-wave link design in the range of 75 GHz to 300 GHz....

  19. Simultaneous multi-channel CMW-band and MMW-band UWB monocycle pulse generation using FWM effect in a highly nonlinear photonic crystal fiber.

    Science.gov (United States)

    Zhang, Fangzheng; Wu, Jian; Fu, Songnian; Xu, Kun; Li, Yan; Hong, Xiaobin; Shum, Ping; Lin, Jintong

    2010-07-19

    We propose and experimentally demonstrate a scheme to simultaneously realize multi-channel centimeter wave (CMW) band and millimeter wave (MMW) band ultra-wideband (UWB) monocycle pulse generation using four wave mixing (FWM) effect in a highly nonlinear photonic crystal fiber (HNL-PCF). Two lightwaves carrying polarity-reversed optical Gaussian pulses with appropriate time delay and another lightwave carrying a 20 GHz clock signal are launched into the HNL-PCF together. By filtering out the FWM idlers, two CMW-band UWB monocycle signals and two MMW-band UWB monocycle signals at 20 GHz are obtained simultaneously. Experimental measurements of the generated UWB monocycle pulses at individual wavelength, which comply with the FCC regulations, verify the feasibility and flexibility of proposed scheme for use in practical UWB communication systems.

  20. High-Performance Solid-State W-Band Power Amplifiers

    Science.gov (United States)

    Gaier, Todd; Samoska, Lorene; Wells, Mary; Ferber, Robert; Pearson, John; Campbell, April; Peralta, Alejandro; Swift, Gerald; Yocum, Paul; Chung, Yun

    2003-01-01

    The figure shows one of four solid-state power amplifiers, each capable of generating an output power greater than or equal to 240 mW over one of four overlapping frequency bands from 71 to 106 GHz. (The bands are 71 to 84, 80 to 92, 88 to 99, and 89 to 106 GHz.) The amplifiers are designed for optimum performance at a temperature of 130 K. These amplifiers were developed specifically for incorporation into frequency-multiplier chains in local oscillators in a low-noise, far-infrared receiving instrument to be launched into outer space to make astrophysical observations. The designs of these amplifiers may also be of interest to designers and manufacturers of terrestrial W-band communication and radar systems. Each amplifier includes a set of six high-electron-mobility transistor (HEMT) GaAs monolithic microwave integrated-circuit (MMIC) chips, microstrip cavities, and other components packaged in a housing made from A-40 silicon-aluminum alloy. This alloy was chosen because, for the original intended spacecraft application, it offers an acceptable compromise among the partially competing requirements for high thermal conductivity, low mass, and low thermal expansion. Problems that were solved in designing the amplifiers included designing connectors and packages to fit the available space; designing microstrip signal-power splitters and combiners; matching of impedances across the frequency bands; matching of the electrical characteristics of those chips installed in parallel power-combining arms; control and levelling of output power across the bands; and designing the MMICs, microstrips, and microstrip cavities to suppress tendencies toward oscillation in several modes, both inside and outside the desired frequency bands.

  1. Fabricating Aluminum Bronze Rotating Band for Large-Caliber Projectiles by High Velocity Arc Spraying

    Science.gov (United States)

    Wu, Bin; Fang, Ling-hui; Chen, Xiao-lei; Zou, Zhi-qiang; Yu, Xu-hua; Chen, Gang

    2014-02-01

    The necessity of finding new rotating band materials and developing corresponding joining technologies for large-caliber projectiles has been revealed by the recent increase in the ballistic performance of high loads. In this paper, aluminum bronze coatings were fabricated by the high velocity arc spraying (HVAS) technique. Microstructure and microhardness of the prepared coatings were investigated. Ring-on-disk dry sliding wear tests were conducted in an ambient condition to examine the tribological behavior of the coatings. Quasi-static engraving processes of rotating bands made of as-sprayed aluminum bronze coating and bulk copper were studied using rate-controlled push test methodology on an MTS 810 Material Testing System. The results show that the as-sprayed aluminum bronze coatings have a dense microstructure with porosity of about 1.6%. Meanwhile, the as-sprayed coating presents a higher microhardness than pure copper. The friction coefficient of coatings is about 0.2-0.3 in the steady state. Tribological mechanisms of the as-sprayed coatings were discussed. The engraving test results show that the aluminum bronze rotating band presents high bonding strength and good plasticity. The HVAS aluminum bronze coating should be a possible substitute for the state-of-the-art copper rotating band.

  2. Atmospheric and Fog Effects on Ultra-Wide Band Radar Operating at Extremely High Frequencies.

    Science.gov (United States)

    Balal, Nezah; Pinhasi, Gad A; Pinhasi, Yosef

    2016-05-23

    The wide band at extremely high frequencies (EHF) above 30 GHz is applicable for high resolution directive radars, resolving the lack of free frequency bands within the lower part of the electromagnetic spectrum. Utilization of ultra-wideband signals in this EHF band is of interest, since it covers a relatively large spectrum, which is free of users, resulting in better resolution in both the longitudinal and transverse dimensions. Noting that frequencies in the millimeter band are subjected to high atmospheric attenuation and dispersion effects, a study of the degradation in the accuracy and resolution is presented. The fact that solid-state millimeter and sub-millimeter radiation sources are producing low power, the method of continuous-wave wideband frequency modulation becomes the natural technique for remote sensing and detection. Millimeter wave radars are used as complementary sensors for the detection of small radar cross-section objects under bad weather conditions, when small objects cannot be seen by optical cameras and infrared detectors. Theoretical analysis for the propagation of a wide "chirped" Frequency-Modulated Continuous-Wave (FMCW) radar signal in a dielectric medium is presented. It is shown that the frequency-dependent (complex) refractivity of the atmospheric medium causes distortions in the phase of the reflected signal, introducing noticeable errors in the longitudinal distance estimations, and at some frequencies may also degrade the resolution.

  3. Spin electronics

    CERN Document Server

    Buhrman, Robert; Daughton, James; Molnár, Stephan; Roukes, Michael

    2004-01-01

    This report is a comparative review of spin electronics ("spintronics") research and development activities in the United States, Japan, and Western Europe conducted by a panel of leading U.S. experts in the field. It covers materials, fabrication and characterization of magnetic nanostructures, magnetism and spin control in magnetic nanostructures, magneto-optical properties of semiconductors, and magnetoelectronics and devices. The panel's conclusions are based on a literature review and a series of site visits to leading spin electronics research centers in Japan and Western Europe. The panel found that Japan is clearly the world leader in new material synthesis and characterization; it is also a leader in magneto-optical properties of semiconductor devices. Europe is strong in theory pertaining to spin electronics, including injection device structures such as tunneling devices, and band structure predictions of materials properties, and in development of magnetic semiconductors and semiconductor heterost...

  4. Probing Shell Correction at High Spin by Neutron Emission of Doubly Magic Nuclei 208pb and 132Sn

    Institute of Scientific and Technical Information of China (English)

    YEWei

    2005-01-01

    Shell effects in particle emission for two doubly magic nuclei 132Sn and 208pb were studied in the framework of Smoluchowski equation taking into account temperature and spin-dependent shell correction. It is shown that the shelle ffects in the emission of pre-scission neutrons are sensitive to the spin dependence of the shell correction at a moderate excitation energy. Therefore, we propose to use neutron multiplicity as an observable to probe the shell correction at high spins.

  5. Probing Shell Correction at High Spin by Neutron Emission of Doubly Magic Nuclei 208pb and 132Sn

    Institute of Scientific and Technical Information of China (English)

    YE Wei

    2005-01-01

    Shell effects in particle emission for two doubly magic nuclei 132 Sn and 208 Pb were studied in the framework of Smoluchowski equation taking into account temperature and spin-dependent shell correction. It is shown that the shell effects in the enission of pre-scission neutrons are sensitive to the spin dependence of the shell correction at a moderate excitation energy. Therefore, we propose to use neutron multiplicity as an observable to probe the shell correction at high spins.

  6. High Magnetic Field-Induced Formation of Banded Microstructures in Lamellar Eutectic Alloys During Directional Solidification

    Science.gov (United States)

    Li, Xi; Fautrelle, Yves; Gagnoud, Annie; Ren, Zhongming; Moreau, Rene

    2016-08-01

    The influences of high magnetic field (up to 12 T) on the morphology of Pb-Sn and Al-Al2Cu lamellar eutectics during directional solidification were investigated. The experimental results indicate that, along with a decrease in eutectic spacing, the banded structure forms at lower growth speeds under high magnetic field and the band spacing decreases as the magnetic field increases. Moreover, the application of a magnetic field enriches the Cu solute in the liquid ahead of the liquid/solid interface during directional solidification of an Al-Al2Cu eutectic alloy. The effects of high magnetic field on the eutectic points of non-ferromagnetic alloys and the stress acting on the eutectic lamellae during directional solidification have been studied. Both thermodynamic evaluation and DTA measurements reveal that the high magnetic field has a negligible effect on the eutectic points of non-ferromagnetic alloys. However, the high magnetic field caused an increase of the nucleation temperature and undercooling. The numerical results indicate that a considerable stress is produced on the eutectic lamellae during directional solidification under high magnetic field. The formation of a banded structure in a lamellar eutectic during directional solidification under high magnetic field may be attributed to both the buildup of the solute in the liquid ahead of the liquid/solid interface and the stress acting on the eutectic lamellae.

  7. A high efficiency C-band internally-matched harmonic tuning GaN power amplifier

    Science.gov (United States)

    Lu, Y.; Zhao, B. C.; Zheng, J. X.; Zhang, H. S.; Zheng, X. F.; Ma, X. H.; Hao, Y.; Ma, P. J.

    2016-09-01

    In this paper, a high efficiency C-band gallium nitride (GaN) internally-matched power amplifier (PA) is presented. This amplifier consists of 2-chips of self-developed GaN high-electron mobility transistors (HEMTs) with 16 mm total gate width on SiC substrate. New harmonic manipulation circuits are induced both in the input and output matching networks for high efficiency matching at fundamental and 2nd-harmonic frequency, respectively. The developed amplifier has achieved 72.1% power added efficiency (PAE) with 107.4 W output power at 5 GHz. To the best of our knowledge, this amplifier exhibits the highest PAE in C-band GaN HEMT amplifiers with over 100 W output power. Additionally, 1000 hours' aging test reveals high reliability for practical applications.

  8. Charge and spin correlations in high temperature superconductors

    Science.gov (United States)

    Hayden, Stephen

    2013-03-01

    The cuprate high temperatures superconductors are characterised by numerous competing, and in some cases, co-existing broken symmetries. A important question is to what extent such additional ordered states exist for compositions with high superconducting transition temperatures. I will discuss high-energy X-ray diffraction measurements which show that a charge density wave state (CDW) develops at zero field in the normal state of superconducting YBa2Cu3O6.67 (Tc = 67 K). This material has a hole doping of 0.12 per copper and a well-ordered oxygen chain superstructure. Below Tc, the application of a magnetic field suppresses superconductivity and enhances the CDW. We find that the CDW and superconductivity are competing orders with similar energy scales, and the high-Tc superconductivity forms from a pre-existing CDW environment. Our results provide a mechanism for the formation of small Fermi surface pockets which can explain the negative Hall and Seebeck effects and the Tc plateau in this material. Work performed in collaboration with J. Chang, E. Blackburn, A. T. Holmes, N. B. Christensen, J. Larsen, J. Mesot, Ruixing Liang, D. A. Bonn, W. N. Hardy, A. Watenphul, M. v. Zimmermann and E. M. Forgan.

  9. Spin-dependent electron transmission through ultra-thin magnetic layers: towards highly discriminative, compact spin detectors

    Energy Technology Data Exchange (ETDEWEB)

    Van der Sluijs, A.M.; Drouhin, H.J.; Lampel, G.; Lassailly, Y.; Marliere, C. [Ecole Polytechnique, 91 - Palaiseau (France)

    1994-10-01

    At low energy, a longitudinally spin-polarized electron beam impinges on an ultrathin, self-supported ferromagnetic target, consisting of a 1 nm-thick cobalt film sandwiched between 21 and 2 nm-thick gold layers, and which is magnetized perpendicularly to the surface. The current transmitted by the target depends on the spin of the electrons. Cesium deposition on both sides of the target increases the transmission ratio from about 1 x 10{sup -5} up to 3 x 10{sup -4} and also increases the transmission spin-asymmetry from 15 to about 40%. Such a structure is well suited to the construction of convenient and compact spin-detectors. (authors). 4 figs., 9 refs.

  10. A Coherent Compton Backscattering High Gain FEL using an X-Band Microwave Undulator

    Energy Technology Data Exchange (ETDEWEB)

    Tantawi, S.; Dolgashev, V.; Nantista, C.; /SLAC; Pellegrini, C.; Rosenzweig, J.; Travish, G.; /UCLA

    2005-12-14

    High power microwave sources at X-Band, delivering 400 to 500 of megawatts for about 400 ns, have been recently developed. These sources can power a microwave undulator with short period and large gap, and can be used in short wavelength FELs reaching the nm region at a beam energy of about 1 GeV. We present here an experiment designed to demonstrate that microwave undulators have the field quality needed for high gain FELs.

  11. Effects of Spin on High-Energy Radiation from Accreting Black Holes

    CERN Document Server

    Riordan, Michael O'; McKinney, Jonathan C

    2016-01-01

    Observations of jets in X-ray binaries show a correlation between radio power and black hole spin. This correlation, if confirmed, points towards the idea that relativistic jets may be powered by the rotational energy of black holes. In order to examine this further, we perform general-relativistic radiative transport calculations on magnetically arrested accretion flows, which are known to produce powerful jets via the Blandford-Znajek (BZ) mechanism. We find that the X-ray and gamma-ray emission strongly depend on spin and inclination angle. Surprisingly, the high-energy power does not show the same dependence on spin as the BZ jet power, but instead can be understood as a redshift effect. In particular, photons observed perpendicular to the spin axis suffer little net redshift until originating from close to the horizon. Such observers see deeper into the hot, dense, highly-magnetized inner disk region. This effect is largest for rapidly rotating black holes due to a combination of frame dragging and decre...

  12. Convergence of valence bands for high thermoelectric performance for p-type InN

    Science.gov (United States)

    Li, Hai-Zhu; Li, Ruo-Ping; Liu, Jun-Hui; Huang, Ming-Ju

    2015-12-01

    Band engineering to converge the bands to achieve high valley degeneracy is one of effective approaches for designing ideal thermoelectric materials. Convergence of many valleys in the valence band may lead to a high Seebeck coefficient, and induce promising thermoelectric performance of p-type InN. In the current work, we have systematically investigated the electronic structure and thermoelectric performance of wurtzite InN by using the density functional theory combined with semiclassical Boltzmann transport theory. Form the results, it can be found that intrinsic InN has a large Seebeck coefficient (254 μV/K) and the largest value of ZeT is 0.77. The transport properties of p-type InN are better than that of n-type one at the optimum carrier concentration, which mainly due to the large Seebeck coefficient for p-type InN, although the electrical conductivity of n-type InN is larger than that of p-type one. We found that the larger Seebeck coefficient for p-type InN may originate from the large valley degeneracy in the valence band. Moreover, the low minimum lattice thermal conductivity for InN is one key factor to become a good thermoelectric material. Therefore, p-type InN could be a potential material for further applications in the thermoelectric area.

  13. E- and W-band high-capacity hybrid fiber-wireless link

    DEFF Research Database (Denmark)

    Vegas Olmos, Juan José; Pang, Xiaodan; Tafur Monroy, Idelfonso

    2014-01-01

    In this paper we summarize the work conducted in our group in the area of E- and W-band optical high-capacity fiber-wireless links. We present performance evaluations of E- and W-band mm-wave signal generation using photonic frequency upconversion employing both VCSELs and ECLs, along with transm......In this paper we summarize the work conducted in our group in the area of E- and W-band optical high-capacity fiber-wireless links. We present performance evaluations of E- and W-band mm-wave signal generation using photonic frequency upconversion employing both VCSELs and ECLs, along...... with transmission over different type of optical fibers and for a number of values for the wireless link distance. Hybrid wireless-optical links can be composed of mature and resilient technology available off-the-shelf, and provide functionalities that can add value to optical access networks, specifically...... in mobile backhaul/fronthaul applications, dense distributed antenna systems and fiber-over-radio scenarios....

  14. Analysis of several high-resolution infrared bands of spiropentane, C5H8

    Energy Technology Data Exchange (ETDEWEB)

    Maki, Arthur G.; Price, Joseph E.; Harzan, J.; Nibler, Joseph W.; Weber, Alfons; Masiello, Tony; Blake, Thomas A.

    2015-06-01

    he high-resolution infrared absorption spectrum of spiropentane (C5H8) has been measured from 200 to 4000 cm 1, and a detailed analysis is presented for eight bands in the region from 700 to 2200 cm 1. Two fundamental perpendicular bands were analyzed, m22 and m24 near 1050 and 780 cm 1, respectively, along with two fundamental parallel bands, m14 and m16 near 1540 and 990 cm1, respectively. Two other fundamentals, m17 and m23, are seen as intense overlapping bands near 880 cm*1 and are Coriolis-coupled, producing a complex mixture in which only P-branch transitions could be tentatively assigned for m17. In addition, three binary combination bands were fit at about 1570, 2082, and 2098 cm*1 which are assigned as either 2m24 or m5 + m16 in the first case, m4 + m22 in the second case, and 2m22 in the latter case. The two l-type resonance constants, q+ and q*, were determined for each of the two perpendicular fundamentals m22 and m24. Those two constants were also responsible for splittings observed in the K = 3 levels of m24. For the ground state the order of the split K = 2 B1/B2 levels has been reversed from that reported previously, based on the measurements and assignments for the m24 band. Rovibrational parameters deduced from the analyses are compared with those obtained from density functional Gaussian calculations at the anharmonic level.

  15. Experimental Studies of W-Band Accelerator Structures at High Field

    Energy Technology Data Exchange (ETDEWEB)

    Hill, Marc E

    2001-02-09

    A high-gradient electron accelerator is desired for high-energy physics research, where frequency scalings of breakdown and trapping of itinerant beamline particles dictates operation of the accelerator at short wavelengths. The first results of design and test of a high-gradient mm-wave linac with an operating frequency at 91.392 GHz (W-band) are presented. A novel approach to particle acceleration is presented employing a planar, dielectric lined waveguide used for particle acceleration. The traveling wave fields in the planar dielectric accelerator (PDA) are analyzed for an idealized structure, along with a circuit equivalent model used for understanding the structure as a microwave circuit. Along with the W-band accelerator structures, other components designed and tested are high power rf windows, high power attenuators, and a high power squeeze-type phase shifter. The design of the accelerator and its components where eased with the aide of numerical simulations using a finite-difference electromagnetic field solver. Manufacturing considerations of the small, delicate mm-wave components and the steps taken to reach a robust fabrication process are detailed. These devices were characterized under low power using a two-port vector network analyzer to verify tune and match, including measurements of the structures' fields using a bead-pull. The measurements are compared with theory throughout. Addition studies of the W-band structures were performed under high power utilizing a 11.424 GHz electron linac as a current source. Test results include W-band power levels of 200 kW, corresponding to fields in the PDA of over 20 MV/m, a higher gradient than any collider. Planar accelerator devices naturally have an rf quadrupole component of the accelerating field. Presented for the first time are the measurements of this effect.

  16. Perpendicular spin transfer torque magnetic random access memories with high spin torque efficiency and thermal stability for embedded applications (invited)

    Energy Technology Data Exchange (ETDEWEB)

    Thomas, Luc, E-mail: luc.thomas@headway.com; Jan, Guenole; Zhu, Jian; Liu, Huanlong; Lee, Yuan-Jen; Le, Son; Tong, Ru-Ying; Pi, Keyu; Wang, Yu-Jen; Shen, Dongna; He, Renren; Haq, Jesmin; Teng, Jeffrey; Lam, Vinh; Huang, Kenlin; Zhong, Tom; Torng, Terry; Wang, Po-Kang [TDK-Headway Technologies, Inc., Milpitas, California 95035 (United States)

    2014-05-07

    Magnetic random access memories based on the spin transfer torque phenomenon (STT-MRAMs) have become one of the leading candidates for next generation memory applications. Among the many attractive features of this technology are its potential for high speed and endurance, read signal margin, low power consumption, scalability, and non-volatility. In this paper, we discuss our recent results on perpendicular STT-MRAM stack designs that show STT efficiency higher than 5 k{sub B}T/μA, energy barriers higher than 100 k{sub B}T at room temperature for sub-40 nm diameter devices, and tunnel magnetoresistance higher than 150%. We use both single device data and results from 8 Mb array to demonstrate data retention sufficient for automotive applications. Moreover, we also demonstrate for the first time thermal stability up to 400 °C exceeding the requirement of Si CMOS back-end processing, thus opening the realm of non-volatile embedded memory to STT-MRAM technology.

  17. PARTICLE-HOLE NATURE OF THE LIGHT HIGH-SPIN TOROIDAL ISOMERS

    Energy Technology Data Exchange (ETDEWEB)

    Staszczak, A. [Maria Curie-Sklodowska University, Poland; Wong, Cheuk-Yin [ORNL

    2015-01-01

    Nuclei under non-collective rotation with a large angular momentum above some threshold can assume a toroidal shape. In our previous work, we showed by using cranked Skyrme Hartree Fock approach that even even, N = Z, high-K, toroidal isomeric states may have general occurrences for light nuclei with 28 < A < 52. We present here some additional results and systematics on the particle-hole nature of these high-spin toroidal isomers.

  18. Properties of neutron-rich hafnium high-spin isomers

    CERN Document Server

    Tungate, G; Walker, P M; Neyens, G; Billowes, J; Flanagan, K; Koester, U H; Litvinov, Y

    It is proposed to study highly-excited multi-quasiparticle isomers in neutron-rich hafnium (Z=72) isotopes. Long half-lives have already been measured for such isomers in the storage ring at GSI, ensuring their accessibility with ISOL production. The present proposal focuses on:\\\\ (i) an on-line experiment to measure isomer properties in $^{183}$Hf and $^{184}$Hf, and\\\\ (ii) an off-line molecular breakup test using REXTRAP, to provide Hf$^{+}$ beams for future laser spectroscopy and greater sensitivity for the future study of more neutron-rich isotopes.

  19. Wide Frequency Band Active Damping Strategy for DFIG System High Frequency Resonance

    DEFF Research Database (Denmark)

    Song, Yipeng; Blaabjerg, Frede

    2016-01-01

    As a popular renewable power generation solution, the Doubly Fed Induction Generator (DFIG) based wind power system may suffer from High Frequency Resonance (HFR) caused by the impedance interaction between the DFIG system and the parallel compensated weak network. A wide frequency band active...... damping strategy for DFIG system HFR, including a high-pass filter and a virtual resistance, is proposed in this paper. The advantages of this active damping strategy are, 1) no resonance frequency detection unit is required, thus the control complexity can be decreased; 2) no active damping parameters...... adjustment is needed within certain wide frequency band, thus the robustness of the proposed active damping strategy can be improved. The parameter design of the high-pass filter cutoff frequency and the virtual resistance are theoretically analyzed with the purpose of satisfactory active damping. A 7.5 k...

  20. DSP/FPGA Design for a High-Speed Programmable S-Band Space Transceiver

    Science.gov (United States)

    Janicik, Jeffrey; Friedman, Assi

    2013-01-01

    Traditional command uplink receivers are very limited in performance capability, take a long time to acquire, cannot operate on both uplink bands (NASA & AFSCN), and only support low-rate communications. As a result, transceivers end up on many programs critical paths, even though they should be a standard purchased spacecraft subsystem. Also, many missions are impacted by the low effective uplink throughput. In order to tackle these challenges, a transceiver was developed that will provide on-site frequency agility, support of high uplink rates, and operation on both NASA and AFSCN frequency bands. The device is a low-power, high-reliability, and high-performance digital signal processing (DSP) demodulator for an on-orbit programmable command receiver.

  1. High-frequency homogenization of zero frequency stop band photonic and phononic crystals

    CERN Document Server

    Antonakakis, Tryfon; Guenneau, Sebastien

    2013-01-01

    We present an accurate methodology for representing the physics of waves, for periodic structures, through effective properties for a replacement bulk medium: This is valid even for media with zero frequency stop-bands and where high frequency phenomena dominate. Since the work of Lord Rayleigh in 1892, low frequency (or quasi-static) behaviour has been neatly encapsulated in effective anisotropic media. However such classical homogenization theories break down in the high-frequency or stop band regime. Higher frequency phenomena are of significant importance in photonics (transverse magnetic waves propagating in infinite conducting parallel fibers), phononics (anti-plane shear waves propagating in isotropic elastic materials with inclusions), and platonics (flexural waves propagating in thin-elastic plates with holes). Fortunately, the recently proposed high-frequency homogenization (HFH) theory is only constrained by the knowledge of standing waves in order to asymptotically reconstruct dispersion curves an...

  2. Theoretical Design of High-spin Organic Molecules with-. N-S-as a Spin-containing Fragment and Heterocycle as End Groups

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Novel stable high-spin molecules possessing three different arranging fashions were designed with -(.) N-S-as a spin-containing (SC) fragment, an aromatic group, such as benzene (1), pyridine (2), pyridazine (3), pyrimidine (4), pyrazine (5) or triazine (6) as end groups (EG), and phenyl as a ferromagnetic coupling (FC) unit.The effects of different EG on the spin multiplicities of the ground states and their stabilities were investigated by means of the AM1-CI approach. All the investigated molecules corresponded to the FC and possessed high-spin ground states. The spin on the two atoms of the SC fragment was not in agreement with the delocalization results in the specific stability of -(.) N-S-. In those molecules, the stabilities of the triplet states decreased when the distance between the atoms of central SC fragments (-N-) increased. The stabilities of the triplet states of compounds 1a-n, 1b-n and 1c-n, with heterocycles as EG were higher than those of the triplet states of those compounds with phenyl as EG. Furthermore, the stabilities of the triplet states of the compounds with pyrimidine and triazine as EG were higher than those with pyridine, pyridazine or pyrazine as EG.

  3. High-Efficiency Resonant RF Spin Rotator with Broad Phase Space Acceptance for Pulsed Polarized Cold Neutron Beams

    CERN Document Server

    Seo, P -N; Bowman, J D; Chupp, T E; Crawford, C; Dabaghyan, M; Dawkins, M; Freedman, S J; Gentile, T; Gericke, M T; Gillis, R C; Greene, G L; Hersman, F W; Jones, G L; Kandes, M; Lamoreaux, S; Lauss, B; Leuschner, M B; Mahurin, R; Mason, M; Mei, J; Mitchell, G S; Nann, H; Page, S A; Penttila, S I; Ramsay, W D; Bacci, A Salas; Santra, S; Sharma, M; Smith, T B; Snow, W M; Wilburn, W S; Zhu, H

    2007-01-01

    We have developed a radio-frequency resonant spin rotator to reverse the neutron polarization in a 9.5 cm x 9.5 cm pulsed cold neutron beam with high efficiency over a broad cold neutron energy range. The effect of the spin reversal by the rotator on the neutron beam phase space is compared qualitatively to RF neutron spin flippers based on adiabatic fast passage. The spin rotator does not change the kinetic energy of the neutrons and leaves the neutron beam phase space unchanged to high precision. We discuss the design of the spin rotator and describe two types of transmission-based neutron spin-flip efficiency measurements where the neutron beam was both polarized and analyzed by optically-polarized 3He neutron spin filters. The efficiency of the spin rotator was measured to be 98.0+/-0.8% on resonance for neutron energies from 3.3 to 18.4 meV over the full phase space of the beam. As an example of the application of this device to an experiment we describe the integration of the RF spin rotator into an app...

  4. The spin temperature of high-redshift damped Lyman-$\\alpha$ systems

    CERN Document Server

    Kanekar, N; Smette, A; Ellison, S L; Ryan-Weber, E V; Momjian, E; Briggs, F H; Lane, W M; Chengalur, J N; Delafosse, T; Grave, J; Jacobsen, D; de Bruyn, A G

    2013-01-01

    We report results from a programme aimed at investigating the temperature of neutral gas in high-redshift damped Lyman-$\\alpha$ absorbers (DLAs). This involved (1) HI 21cm absorption studies of a large DLA sample, (2) VLBI studies to measure the low-frequency quasar core fractions, and (3) optical/ultraviolet spectroscopy to determine DLA metallicities and velocity widths. Including literature data, our sample consists of 37 DLAs with estimates of the spin temperature $T_s$ and the covering factor. We find a strong $4\\sigma$) difference between the $T_s$ distributions in high-z (z>2.4) and low-z (z1 sub-sample. Since z>1 DLAs have angular diameter distances comparable to or larger than those of the background quasars, they have similar efficiency in covering the quasars. Low covering factors in high-z DLAs thus cannot account for the observed redshift evolution in spin temperatures. (Abstract abridged.)

  5. High-Density Physical Random Number Generator Using Spin Signals in Multidomain Ferromagnetic Layer

    Directory of Open Access Journals (Sweden)

    Sungwoo Chun

    2015-01-01

    Full Text Available A high-density random number generator (RNG based on spin signals in a multidomain ferromagnetic layer in a magnetic tunnel junction (MTJ is proposed and fabricated. Unlike conventional spin-based RNGs, the proposed method does not require one to control an applied current, leading to a time delay in the system. RNG demonstrations are performed at room temperature. The randomness of the bit sequences generated by the proposed RNG is verified using the FIPS 140-2 statistical test suite provided by the NIST. The test results validate the effectiveness of the proposed RNGs. Our results suggest that we can obtain high-density, ultrafast RNGs if we can achieve high integration on the chip.

  6. Revisiting spin-lattice relaxation time measurements for dilute spins in high-resolution solid-state NMR spectroscopy

    Science.gov (United States)

    Fu, Riqiang; Li, Jun; Cui, Jingyu; Peng, Xinhua

    2016-07-01

    Numerous nuclear magnetic resonance (NMR) measurements of spin-lattice relaxation times (T1S) for dilute spins such as 13C have led to investigations of the motional dynamics of individual functional groups in solid materials. In this work, we revisit the Solomon equations and analyze how the heteronuclear cross relaxation between the dilute S (e.g. 13C) and abundant I (e.g. 1H) spins affects the measured T1S values in solid-state NMR in the absence of 1H saturation during the recovery time. It is found theoretically that at the beginning of the S spin magnetization recovery, the existence of non-equilibrium I magnetization introduces the heteronuclear cross relaxation effect onto the recovery of the S spin magnetization and confirmed experimentally that such a heteronuclear cross relaxation effect results in the recovery overshoot phenomena for the dilute spins when T1S is on the same order of T1H, leading to inaccurate measurements of the T1S values. Even when T1S is ten times larger than T1H, the heteronuclear cross relaxation effect on the measured T1S values is still noticeable. Furthermore, this cross relaxation effect on recovery trajectory of the S spins can be manipulated and even suppressed by preparing the initial I and S magnetization, so as to obtain the accurate T1S values. A sample of natural abundance L-isoleucine powder has been used to demonstrate the T1S measurements and their corresponding measured T1C values under various experimental conditions.

  7. Observation of a Collective Oblate Band in 137Ce

    Institute of Scientific and Technical Information of China (English)

    ZHU Sheng-Jiang; Jon Myang-Gil; WEN Shu-Xian; WU Xiao-Guang; LIU Xiang-An; ZHU Ling-Yan; LI Ming; GAN Cui-Yun; M. Sakhaee; YANG Li-Ming; ZHANG Zheng; JIANG Zhuo; LONG Gui-Lu

    2000-01-01

    High spin states in 137 Ce have been studied by using the heavy-ion induced reaction 124Sn(18 O, 5n) carried out at China Institute of Atomic Energy. Partial level scheme with spin up to (43/2-), including a high spin collective rotational band observed for the first time, has been established. The collective band shows the properties similar to those oblate bands with γ ~-60° in neighboring nuclei and probably originates from the five quasi-particle configuration νs1/2 [vh11/2]2 π97/2 πh11/2. The characteristics of this oblate band have been discussed.

  8. Theoretical design of high-spin biradical molecules with heterocycles as coupling unit

    Institute of Scientific and Technical Information of China (English)

    WANG Li-min; CHU De-qing; ZHANG Jing-ping; WANG Rong-shun

    2006-01-01

    Computational studies of a class of potentially stable high-spin biradicals that two-atom-three-electron spin centers SC units connected by heterocycles FC and phenyl EG were described. The geometry and character of the spin exchange interaction were obtained by means of UB3LYP/6-31G*. The results show that the molecules possessing three different arranged fashions are designed with—·N—S as SC fragment,pyridine as FC and phenyl as EG,the spin densities on the two atoms of the SC fragment are different from the delocalization results in the specific stability of—·N—S. In these molecules,the stabilities of the triplet states decrease when the distance between the atoms of central SC (—N—) increases. Molecules with—·N—S as SC fragment,pyridine,pyrazine and triazine as FC and phenyl as EG are designed,the stability of triplet states for the molecule with pyridine as FC is the highest,and that for the molecule with pyrazine as FC is the lowest. Molecules with—·N—S,— ··N—O and—·N—NH as SC fragment,pyridine as FC and phenyl as EG are designed,the stability of triplet states for the molecule with—·N—S as SC is the highest,that for the molecule with—·N—NH as SC is the lowest.

  9. FERROELECTRIC SWITCH FOR A HIGH-POWER Ka-BAND ACTIVE PULSE COMPRESSOR

    Energy Technology Data Exchange (ETDEWEB)

    Hirshfield, Jay L. [Omega-P, Inc.

    2013-12-18

    Results are presented for design of a high-power microwave switch for operation at 34.3 GHz, intended for use in an active RF pulse compressor. The active element in the switch is a ring of ferroelectric material, whose dielectric constant can be rapidly changed by application of a high-voltage pulse. As envisioned, two of these switches would be built into a pair of delay lines, as in SLED-II at SLAC, so as to allow 30-MW μs-length Ka-band pulses to be compressed in time by a factor-of-9 and multiplied in amplitude to generate 200 MW peak power pulses. Such high-power pulses could be used for testing and evaluation of high-gradient mm-wave accelerator structures, for example. Evaluation of the switch design was carried out with an X-band (11.43 GHz) prototype, built to incorporate all the features required for the Ka-band version.

  10. High-Performance transparent Meta-surface for C-/X-Band Lens Antenna Application

    Science.gov (United States)

    Cai, Tong; Wang, Guangming

    2017-01-01

    A novel strategy of designing high-performance transparent meta-surfaces is proposed by using an ABBA system. The ABBA element provides a new freedom to largely enhance the transmission of a transmissive meta-surface and suppress the fluctuations in the transmission amplitude by tuning the coupling among cascaded layers. Dual-band operating property is straightforwardly performed by employing the polarization-control principle. A well-designed transparent meta-surface, operating at f 1=6.5 GHz and f 2=10.5 GHz, consists of 13×17 ABBA elements with parabolic phase distributions along different dimensions. Perfect focusing effects with the same focal length and small reflection are unambiguously observed at both frequencies under excitation of differently-polarized waves, indicating strong phase compensating capacities and high efficiencies of the meta-lens. For practical application, a dual-band lens antenna (LA) is implemented by launching the carefully-designed meta-lens with a self-made Vivaldi antenna. Numerical and experimental results coincide well, indicating that the proposed LA advances in many aspects such as high radiation gain of 18.7 dB at f 1 and 23 dB at f 2, competitive aperture efficiencies better than 30% and also a simple fabrication process based on a standard printed-circuit-board (PCB) technology. The finding opens up a new avenue to design high-performance meta-surfaces operating in multi-band or achieving integrated functionalities.

  11. Ferroelectric switch for a high-power Ka-band active pulse compressor

    Energy Technology Data Exchange (ETDEWEB)

    Hirshfield, Jay L. [Omega-P, Inc., New Haven, CT (United States)

    2013-12-18

    Results are presented for design of a high-power microwave switch for operation at 34.3 GHz, intended for use in an active RF pulse compressor. The active element in the switch is a ring of ferroelectric material, whose dielectric constant can be rapidly changed by application of a high-voltage pulse. As envisioned, two of these switches would be built into a pair of delay lines, as in SLED-II at SLAC, so as to allow 30-MW μs-length Ka-band pulses to be compressed in time by a factor-of-9 and multiplied in amplitude to generate 200 MW peak power pulses. Such high-power pulses could be used for testing and evaluation of high-gradient mm-wave accelerator structures, for example. Evaluation of the switch design was carried out with an X-band (11.43 GHz) prototype, built to incorporate all the features required for the Ka-band version.

  12. High resolution investigation of the v3 band of trifluoromethyliodide (CF3I)

    Science.gov (United States)

    Willaert, F.; Roy, P.; Manceron, L.; Perrin, A.; Kwabia-Tchana, F.; Appadoo, D.; McNaughton, D.; Medcraft, C.; Demaison, J.

    2015-09-01

    The high-resolution absorption spectrum of trifluoromethyliodide (CF3I), an alternative gas to chlorofluorocarbons but with potential greenhouse effects, has been recorded at 0.001 cm-1 resolution in the 200-350 cm-1 region with the Bruker IFS125HR Fourier transform spectrometer at synchrotron SOLEIL. Due to the spectral congestion and the presence of numerous hot bands, the spectra have been recorded at the AILES Beamline facility at SOLEIL either at room temperature using a 150 m optical path length cell or at 163 K using the new LISA-SOLEIL cryogenic cell and at the Australian synchrotron using a flow cooling cell. This enables a detailed analysis of the v3 band at 286.29712(3) cm-1 of CF3I. The results of previous microwave measurements in the v3 = 1 and v6 = 1 vibrational states (Walters and Whiffen, 1983; Wahi, 1987) were combined with those of the present infrared analysis of the v3 band to obtain an improved set of parameters for the v3 = 1 (C-I stretching) and v6 = 1 (I-C-F bending) interacting vibrational states accounting for the Coriolis resonance coupling the v3 = 1 energy levels with those of the dark v6 = 1 state (located at ∼261.5 or at ∼267.6 cm-1). Finally, a first investigation of the 2v3 - v3 hot band is also performed.

  13. Banded applications are highly effective in minimising herbicide migration from furrow-irrigated sugar cane.

    Science.gov (United States)

    Oliver, Danielle P; Anderson, Jenny S; Davis, Aaron; Lewis, Stephen; Brodie, Jon; Kookana, Rai

    2014-01-01

    Runoff from farm fields is a common source of herbicide residues in surface waters in many agricultural industries around the world. In Queensland, Australia, the runoff of PSII inhibitor herbicides (in particular diuron and atrazine) is a major concern due to their potential impact on the Great Barrier Reef. This study compared the conventional practice of broadcast application of herbicides in sugarcane production across the whole field with the banded application of particular herbicides onto raised beds only using a shielded sprayer. This study found that the application of two moderately soluble herbicides, diuron and atrazine, to only the raised beds decreased the average total load of both herbicides moving off-site by >90% compared with the conventional treatment. This was despite the area being covered with the herbicides by the banded application being only 60% less than with the conventional treatment. The average total amount of atrazine in drainage water was 7.5% of the active ingredient applied in the conventional treatment compared with 1.8% of the active ingredient applied in the banded application treatment. Similarly, the average total amount of diuron in drainage water was 4.6% of that applied in the conventional treatment compared with 0.9% of that applied in the banded application treatment. This study demonstrates that the application of diuron and atrazine to raised beds only is a highly effective way of minimising migration of these herbicides in drainage water from furrow irrigated sugarcane.

  14. Using Measurements of Fill Factor at High Irradiance to Deduce Heterobarrier Band Offsets: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Olson, J. M.; Steiner, M. A.; Kanevce, A.

    2011-07-01

    Using a 2D device simulation tool, we examine the high irradiance behavior of a single junction, GaAs concentrator cell as a function of the doping in the back surface confinement layer. The confinement layer is designed to be a barrier for both holes and electrons in the base of the solar cell. For a p-type base we show that the FF of the cell at high concentrations is a strong function of both the magnitude of the valence band offset and the doping level in the barrier. In short, for a given valence band offset (VBO), there is a critical barrier doping, below which the FF drops rapidly with lower doping. This behavior is confirmed experimentally for a GaInP/GaAs double heterostructure solar cell where the critical doping concentration (at 500 suns) in the back surface confinement layer is ~1e18 cm-3 for a VBO of 300 meV.

  15. Impact of the Electronic Band Structure in High-Harmonic Generation Spectra of Solids

    Science.gov (United States)

    Tancogne-Dejean, Nicolas; Mücke, Oliver D.; Kärtner, Franz X.; Rubio, Angel

    2017-02-01

    An accurate analytic model describing the microscopic mechanism of high-harmonic generation (HHG) in solids is derived. Extensive first-principles simulations within a time-dependent density-functional framework corroborate the conclusions of the model. Our results reveal that (i) the emitted HHG spectra are highly anisotropic and laser-polarization dependent even for cubic crystals; (ii) the harmonic emission is enhanced by the inhomogeneity of the electron-nuclei potential; the yield is increased for heavier atoms; and (iii) the cutoff photon energy is driver-wavelength independent. Moreover, we show that it is possible to predict the laser polarization for optimal HHG in bulk crystals solely from the knowledge of their electronic band structure. Our results pave the way to better control and optimize HHG in solids by engineering their band structure.

  16. Impact of the electronic band structure in high-harmonic generation spectra of solids

    CERN Document Server

    Tancogne-Dejean, Nicolas; Kärtner, Franz X; Rubio, Angel

    2016-01-01

    An accurate analytic model describing high-harmonic generation (HHG) in solids is derived. Extensive first-principles simulations within a time-dependent density-functional framework corroborate the conclusions of the model. Our results reveal that: (i) the emitted HHG spectra are highly anisotropic and laser-polarization dependent even for cubic crystals, (ii) the harmonic emission is enhanced by the inhomogeneity of the electron-nuclei potential, the yield is increased for heavier atoms, and (iii) the cutoff photon energy is driver-wavelength independent. Moreover, we show that it is possible to predict the laser polarization for optimal HHG in bulk crystals solely from the knowledge of their electronic band structure. Our results pave the way to better control and optimize HHG in solids by engineering their band structure.

  17. Structure of high-spin states in A {approx} 60 region

    Energy Technology Data Exchange (ETDEWEB)

    Nakada, Hitoshi [Chiba Univ. (Japan); Furutaka, K.; Hatsukawa, Y. [and others

    1998-03-01

    High-spin states in the proton-rich Cu-Zn nuclei are investigated by the experiments at JAERI. New levels and {gamma}-rays are identified by the particle-{gamma}-{gamma} coincidence, and J{sup P} assignments are made via the DCO ratio analysis. Yrast sequences are observed up to J {approx} 18 for {sup 62}Zn, and {sup 64}Zn, J {approx} 27/2 for {sup 61}Cu and J {approx} 23/2 for {sup 63}Cu. Though we cannot settle new J{sup P} values for {sup 61,63}Zn, their yrast sequence is also extended. In {sup 64}Zn, a doublet of {gamma}-rays is discovered at 1315 keV, clarifying the similarity in the level scheme between {sup 62}Zn and {sup 64}Zn. We reproduce the yrast levels by a shell-model calculation, by which structure of the high-spin states is further studied. A parity change in the yrast sequence is established, in which the unique-parity orbit 0g{sub 9/2} plays an essential role; one nucleon excitation to g{sub 9/2} gains high angular momentum with low seniority, at the cost of the single-parity energy. Second parity-change is also suggested by the calculation. Such parity change seems characteristic to spherical or nearly spherical nuclei. In {sup 61}Cu, concentration of the {gamma}-ray intensity is observed. This happens because a stretched 3-quasiparticle configuration including 0g{sub 9/2} is relatively stable, similarly to some isomers. Thus, by studying the structure of the high-spin states of the A {approx} 60 nuclei, we have clarified the role of unique-parity orbit in high-spin states, which may be generic to spherical and nearly spherical nuclei. (J.P.N.)

  18. Spin Generation Via Bulk Spin Current in Three Dimensional Topological Insulators

    Science.gov (United States)

    Peng, Xingyue

    To date, charge transport and spin generation in three-dimensional topological insulators (3D TIs) are primarily modeled as a single-surface phenomenon. We propose a new mechanism of spin generation where the role of the insulating yet topologically non-trivial bulk becomes explicit: an external electric field creates a transverse pure spin current through the bulk of a 3D TI, which transports spins between the top and bottom surfaces and leads to spin accumulation on both. The surface spin density and charge current are then proportional to the spin relaxation time, which for a sufficiently high disorder level can be extended by nonmagnetic scattering analogous to the Dyakonov-Perel spin relaxation mechanism. This new spin generation mechanism suggests a distinct and practical strategy for the enhancement of surface spin polarization by increasing nonmagnetic impurity concentration. Numerical results obtained by coherent potential approximation (CPA) based on a 4-band lattice model confirm that this spin generation mechanism originates from the unique topological connection of the top and bottom surfaces and is absent in other two dimensional systems such as graphene, even though they possess a similar Dirac cone-type dispersion.

  19. Experience Operating an X-band High-Power Test Stand at CERN

    CERN Document Server

    Catalan-Lasheras, N; Doebert, S; Farabolini, W; Kovermann, J; McMonagle, G; Rey, S; Syratchev, I; Timeo, L; Wuensch, W; Woolley, B; Tagg, J

    2014-01-01

    CERN has constructed and is operating a klystron-based X-band test stand, called Xbox-1, dedicated to the high-gradient testing of prototype accelerating structures for CLIC and other applications such as FELs. The test stand has now been in operation for a year and significant progress has been made in understanding the system, improving its reliability, upgrading hardware and implementing automatic algorithms for conditioning the accelerating structures.

  20. Gamma Vibrational Bands and Chiral Doublet Bands in A≈100 Neutron-rich Nuclei

    Institute of Scientific and Technical Information of China (English)

    ZHU Sheng-jiang; DING Huai-bo; J.H.Hamilton; A.V.Ramayya; CHE Xing-lai; J.K.Hwang; Y.X.Luo; J.O.Rasmussen; K.Li; WANG Jian-guo; XU Qiang; GU Long; YANG Yun-yi; S.Frauendorf; V.Dimitrov

    2009-01-01

    The level structures of neutron-rich ~(105)Mo,~(106)Mo,~(108)Mo and 110Ru nuclei in A≈100 region have been carefully investigated by coincidence measurements of the prompt γ-rays populated in the spontaneous fission of ~(252)Cf with the Gammasphere detector array.In 105Mo,one-phonon K =9/2 and two-phonon K=13/2 γ-vibrational bands have been identified.In ~(108)Mo,one-phonon γ-vibrational band is expanded and two-phonon γ-vibrational band has been identified.Two similar sets of bands in ~(106)Mo and ~(110)Ru are observed to high spins,which have been proposed as the soft chiral γ-vibrational bands.The characteristics for these γ-vibrational bands and chiral doublet bands have been discussed.

  1. Puncture initial data for black-hole binaries with high spins and high boosts

    Science.gov (United States)

    Ruchlin, Ian; Healy, James; Lousto, Carlos O.; Zlochower, Yosef

    2017-01-01

    We solve the Hamiltonian and momentum constraints of general relativity for two black holes with nearly extremal spins and relativistic boosts in the puncture formalism. We use a non-conformally-flat ansatz with an attenuated superposition of two Lorentz-boosted, conformally Kerr or conformally Schwarzschild 3-metrics and their corresponding extrinsic curvatures. We compare evolutions of these data with the standard Bowen-York conformally flat ansatz (technically limited to intrinsic spins χ =S /MADM2=0.928 and boosts P /MADM=0.897 ), finding, typically, an order of magnitude smaller burst of spurious radiation and agreement with inspiral and merger. As a first case study, we evolve two equal-mass black holes from rest with an initial separation of d =12 M and spins χi=Si/mi2=0.99 , compute the waveforms produced by the collision, the energy and angular momentum radiated, and the recoil of the final remnant black hole. We find that the black-hole trajectories curve at close separations, leading to the radiation of angular momentum. We also study orbiting nonspinning and moderate-spin black-hole binaries and compare these with standard Bowen-York data. We find a substantial reduction in the nonphysical initial burst of radiation which leads to cleaner waveforms. Finally, we study the case of orbiting binary black-hole systems with spin magnitude χi=0.95 in an aligned configuration and compare waveform and final remnant results with those of the SXS Collaboration [54 A. H. Mroue et al., Phys. Rev. Lett. 111, 241104 (2013)., 10.1103/PhysRevLett.111.241104], finding excellent agreement. This represents the first moving puncture evolution of orbiting and spinning black holes exceeding the Bowen-York limit. Finally, we study different choices of the initial lapse and lapse evolution equation in the moving puncture approach to improve the accuracy and efficiency of the simulations.

  2. High spin structure of {sup 35}Cl and the sd-fp shell gap

    Energy Technology Data Exchange (ETDEWEB)

    Kshetri, Ritesh [Saha Institute of Nuclear Physics, 1/AF Bidhan Nagar, Kolkata 700064 (India); Saha Sarkar, M. [Saha Institute of Nuclear Physics, 1/AF Bidhan Nagar, Kolkata 700064 (India)]. E-mail: maitrayee.sahasarkar@saha.ac.in; Ray, Indrani [Saha Institute of Nuclear Physics, 1/AF Bidhan Nagar, Kolkata 700064 (India); Banerjee, P. [Saha Institute of Nuclear Physics, 1/AF Bidhan Nagar, Kolkata 700064 (India); Sarkar, S. [Department of Physics, Bengal Engineering and Science University, Shibpur, Howrah 711103 (India); Raut, Rajarshi [Saha Institute of Nuclear Physics, 1/AF Bidhan Nagar, Kolkata 700064 (India); Goswami, A. [Saha Institute of Nuclear Physics, 1/AF Bidhan Nagar, Kolkata 700064 (India); Chatterjee, J.M. [Saha Institute of Nuclear Physics, 1/AF Bidhan Nagar, Kolkata 700064 (India); Chattopadhyay, S. [Saha Institute of Nuclear Physics, 1/AF Bidhan Nagar, Kolkata 700064 (India); Datta Pramanik, U. [Saha Institute of Nuclear Physics, 1/AF Bidhan Nagar, Kolkata 700064 (India); Mukherjee, A. [Saha Institute of Nuclear Physics, 1/AF Bidhan Nagar, Kolkata 700064 (India); Dey, C.C. [Saha Institute of Nuclear Physics, 1/AF Bidhan Nagar, Kolkata 700064 (India); Bhattacharya, S. [Saha Institute of Nuclear Physics, 1/AF Bidhan Nagar, Kolkata 700064 (India); Dasmahapatra, B. [Saha Institute of Nuclear Physics, 1/AF Bidhan Nagar, Kolkata 700064 (India); Bhowal, Samit [Department of Physics, Surendranath Evening College, Kolkata 700009 (India); Gangopadhyay, G. [University of Calcutta, 92, Acharya Prafulla Chandra Road, Kolkata 700009 (India); Datta, P. [Anandamohan College, 102/1, Raja Rammohan Sarani, Kolkata 700009 (India); Jain, H.C. [Tata Institute of Fundamental Research, Mumbai 400005 (India); Bhowmik, R.K. [Inter-University Accelerator Centre, Aruna Asaf Ali Marg, New Delhi 110067 (India); Muralithar, S.; Singh, R.P.; Kumar, R. [Inter-University Accelerator Centre, Aruna Asaf Ali Marg, New Delhi 110067 (India)

    2007-01-15

    The high spin states of {sup 35}Cl have been studied by in-beam {gamma}-spectroscopy following the fusion-evaporation reaction {sup 12}C({sup 28}Si,{alpha}p){sup 35}Cl at E{sub lab}=70 and 88 MeV, using the Indian National Gamma (Clover) Array (INGA). Lifetimes of six new excited states have been estimated for the first time. To understand the underlying structure of the levels and transition mechanisms, experimental results have been compared with those from the large basis cross-shell shell model calculations. Involvement of orbitals from fp shell and squeezing of the sd-fp shell gap seem to be essential for reliable reproduction of high spin states.

  3. High-performance spinning device for DVD-based micromechanical signal transduction

    Science.gov (United States)

    Hwu, En-Te; Chen, Ching-Hsiu; Bosco, Filippo G.; Wang, Wei-Min; Ko, Hsien-Chen; Hwang, Ing-Shouh; Boisen, Anja; Huang, Kuang-Yuh

    2013-04-01

    Here we report a high-throughput spinning device for nanometric scale measurements of microstructures with instrumentation details and experimental results. The readout technology implemented in the designed disc-like device is based on a DVD data storage optical pick-up unit (OPU). With a spinning mechanism, this device can simultaneously measure surface topography, mechanical deflections and resonance frequencies of several microfabricated beams at a high speed. In biochemical sensing applications, the OPU can measure bending changes of functionalized microcantilevers, providing a statistically robust and label-free bio-detection analysis of multiple compounds. The signal-to-noise ratio (S/N) is demonstrated from statistical measurements as 1.2 with arginine detection at 750 nM concentration. Practically, the OPU can measure up to 480 individual cantilever sensors per second with nanometer resolution. The opto-mechanical optimization of the device design and settings for biochemical detection are described.

  4. Mass measurements and implications for the energy of the high-spin isomer in 94Ag

    CERN Document Server

    Kankainen, A; Batist, L; Eliseev, S; Eronen, T; Hager, U; Hakala, J; Jokinen, A; Moore, I D; Novikov, Yu N; Pentillä, H; Popov, A; Rahaman, S; Rinta-Antila, S; Rissanen, J; Saastamoinen, A; Seliverstov, D M; Sonoda, T; Vorobjev, G; Weber, C; Äystö, J

    2008-01-01

    Nuclides in the vicinity of 94Ag have been studied with the Penning trap mass spectrometer JYFLTRAP at IGISOL. The masses of the two-proton decay daughter 92Rh and the beta-decay daughter 94Pd of the high-spin isomer in 94Ag have been measured and the masses of 93Pd and 94Ag have been deduced. When combined with the data from the one-proton or two-proton decay experiments, the results lead to contradictory mass excess values for the high-spin isomer in 94Ag, -46370(170) keV or -44970(100) keV, corresponding to excitation energies of 6960(400) keV or 8360(370) keV, respectively.

  5. Critical parameters and universal amplitude ratios of two-dimensional spin-S Ising models using high- and low-temperature expansions

    CERN Document Server

    Butera, P

    2003-01-01

    For the study of Ising models of general spin S on the square lattice, we have combined our recently extended high-temperature expansions with the low-temperature expansions derived some time ago by Enting, Guttmann and Jensen. We have computed for the first time various critical parameters and improved the estimates of others. Moreover the properties of hyperscaling and of universality (spin S independence) of exponents and of various dimensionless amplitude combinations have been verified accurately. Assuming the validity of the lattice-lattice scaling, from our estimates of critical amplitudes for the square lattice we have also obtained estimates of the corresponding amplitudes for the spin S Ising model on the triangular, honeycomb, and kagome` lattices.

  6. Improved Wetland Classification Using Eight-Band High Resolution Satellite Imagery and a Hybrid Approach

    Directory of Open Access Journals (Sweden)

    Charles R. Lane

    2014-12-01

    Full Text Available Although remote sensing technology has long been used in wetland inventory and monitoring, the accuracy and detail level of wetland maps derived with moderate resolution imagery and traditional techniques have been limited and often unsatisfactory. We explored and evaluated the utility of a newly launched high-resolution, eight-band satellite system (Worldview-2; WV2 for identifying and classifying freshwater deltaic wetland vegetation and aquatic habitats in the Selenga River Delta of Lake Baikal, Russia, using a hybrid approach and a novel application of Indicator Species Analysis (ISA. We achieved an overall classification accuracy of 86.5% (Kappa coefficient: 0.85 for 22 classes of aquatic and wetland habitats and found that additional metrics, such as the Normalized Difference Vegetation Index and image texture, were valuable for improving the overall classification accuracy and particularly for discriminating among certain habitat classes. Our analysis demonstrated that including WV2’s four spectral bands from parts of the spectrum less commonly used in remote sensing analyses, along with the more traditional bandwidths, contributed to the increase in the overall classification accuracy by ~4% overall, but with considerable increases in our ability to discriminate certain communities. The coastal band improved differentiating open water and aquatic (i.e., vegetated habitats, and the yellow, red-edge, and near-infrared 2 bands improved discrimination among different vegetated aquatic and terrestrial habitats. The use of ISA provided statistical rigor in developing associations between spectral classes and field-based data. Our analyses demonstrated the utility of a hybrid approach and the benefit of additional bands and metrics in providing the first spatially explicit mapping of a large and heterogeneous wetland system.

  7. Development of III-Sb Quantum Dot Systems for High Efficiency Intermediate Band Solar Cells

    Energy Technology Data Exchange (ETDEWEB)

    Huffaker, Diana [Univ. of California, Los Angeles, CA (United States); Hubbard, Seth [Rochester Inst. of Technology, NY (United States); Norman, Andrew [National Renewable Energy Lab. (NREL), Golden, CO (United States)

    2015-07-31

    This project aimed to develop solar cells that can help reduce cost per watt. This work focused on developing solar cells that utilize quantum dot (QD) nanomaterials to provide multijunction solar cell efficiency at the cost of single junction solar cell. We focused on a novel concept known as intermediate band solar cells (IBSC) where an additional energy band is inserted in a single solar cell to accommodate sub-bandgap photons absorption which otherwise are lost through transmission. The additional energy band can be achieved by growing QDs within a solar cell p-n junction. Though numerous studies have been conducted to develop such QD systems, very small improvements in solar energy conversion efficiency have been reported. This is mainly due to non-optimal material parameters such as band gap, band offset etc. In this work, we identified and developed a novel QD material system that meets the requirements of IBSC more closely than the current state-of-the-art technology. To achieve these goals, we focused on three important areas of solar cell design: band structure calculations of new materials, efficient device design for high efficiency, and development of new semiconductor materials. In this project, we focused on III-Sb materials as they possess a wide range of energy bandgaps from 0.2 eV to 2eV. Despite the difficulty involved in realizing these materials, we were successfully developed these materials through a systematic approach. Materials studied in this work are AlAsSb (Aluminum Arsenide Antimonide), InAlAs (Indium Aluminum Arsenide) and InAs (Indium Arsenide). InAs was used to develop QD layers within AlAsSb and InAlAs p-n junctions. As the QDs have very small volume, up to 30 QD layers been inserted into the p-n junction to enhance light absorption. These QD multi-stack devices helped in understanding the challenges associated with the development of quantum dot solar cells. The results from this work show that the quantum dot solar cells indeed

  8. Structure of nearly degenerate dipole bands in {sup 108}Ag

    Energy Technology Data Exchange (ETDEWEB)

    Sethi, J. [Tata Institute of Fundamental Research, Colaba, Mumbai 400 005 (India); Palit, R., E-mail: palit@tifr.res.in [Tata Institute of Fundamental Research, Colaba, Mumbai 400 005 (India); Saha, S.; Trivedi, T. [Tata Institute of Fundamental Research, Colaba, Mumbai 400 005 (India); Bhat, G.H.; Sheikh, J.A. [Department of Physics, University of Kashmir, Srinagar 190 006 (India); Datta, P. [Ananda Mohan College, Kolkata 700009 (India); Carroll, J.J. [US Army Research Laboratory, Adelphi, MD 20783 (United States); Chattopadhyay, S. [Saha Institute of Nuclear Physics, Kolkata 700064 (India); Donthi, R. [Tata Institute of Fundamental Research, Colaba, Mumbai 400 005 (India); Garg, U. [University of Notre Dame, Notre Dame, IN 46556 (United States); Jadhav, S.; Jain, H.C. [Tata Institute of Fundamental Research, Colaba, Mumbai 400 005 (India); Karamian, S. [Joint Institute for Nuclear Research, Dubna 141980 (Russian Federation); Kumar, S. [University of Delhi, Delhi 110007 (India); Litz, M.S. [US Army Research Laboratory, Adelphi, MD 20783 (United States); Mehta, D. [Panjab University, Chandigarh 160014 (India); Naidu, B.S. [Tata Institute of Fundamental Research, Colaba, Mumbai 400 005 (India); Naik, Z. [Sambalpur University, Sambalpur 143005 (India); Sihotra, S. [Panjab University, Chandigarh 160014 (India); and others

    2013-08-09

    The high spin negative parity states of {sup 108}Ag have been investigated with the {sup 11}B + {sup 100}Mo reaction at 39 MeV beam energy using the INGA facility at TIFR, Mumbai. From the γ–γ coincidence analysis, an excited negative parity band has been established and found to be nearly degenerate with the ground state band. The spin and parity of the levels are assigned using angular correlation and polarization measurements. This pair of degenerate bands in {sup 108}Ag is studied using the recently developed microscopic triaxial projected shell model approach. The observed energy levels and the ratio of the electromagnetic transition probabilities of these bands in this isotope are well reproduced by the present model. Further, it is shown that the partner band has a different quasiparticle structure as compared to the yrast band.

  9. Synthesis and spectroscopic characterization of high-spin mononuclear iron(II) p-semiquinonate complexes.

    Science.gov (United States)

    Baum, Amanda E; Park, Heaweon; Lindeman, Sergey V; Fiedler, Adam T

    2014-12-01

    Two mononuclear iron(II) p-semiquinonate (pSQ) complexes have been generated via one-electron reduction of precursor complexes containing a substituted 1,4-naphthoquinone ligand. Detailed spectroscopic and computational analysis confirmed the presence of a coordinated pSQ radical ferromagnetically coupled to the high-spin Fe(II) center. The complexes are intended to model electronic interactions between (semi)quinone and iron cofactors in biology.

  10. Synthesis and Spectroscopic Characterization of High-Spin Mononuclear Iron(II) p-Semiquinonate Complexes

    OpenAIRE

    Baum, Amanda E.; Park, Heaweon; Lindeman, Sergey V.; Fiedler, Adam T.

    2014-01-01

    Two mononuclear iron(II) p-semiquinonate (pSQ) complexes have been generated via one-electron reduction of precursor complexes containing a substituted 1,4-naphthoquinone ligand. Detailed spectroscopic and computational analysis confirmed the presence of a coordinated pSQ radical ferromagnetically coupled to the high-spin FeII center. The complexes are intended to model electronic interactions between (semi)quinone and iron cofactors in biology.

  11. High-dimensional Gaussian fields with isotropic increments seen through spin glasses

    CERN Document Server

    Klimovsky, Anton

    2011-01-01

    We study the free energy of a particle in (arbitrary) high-dimensional Gaussian random potentials with isotropic increments. We prove a computable saddle-point variational representation in terms of a Parisi-type functional for the free energy in the infinite-dimensional limit. The proofs are based on the techniques developed in the course of the rigorous analysis of the Sherrington-Kirkpatrick model with vector spins.

  12. High Resolution Magic Angle Spinning Nuclear Magnetic Resonance (HRMAS NMR) for Studies of Reactive Fabrics

    Science.gov (United States)

    2015-11-01

    Magnetic Resonance (HRMAS NMR) for Studies of Reactive Fabrics 5a. CONTRACT NUMBER W911SR-11-C-0047 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER...ECBC-TR-1326 HIGH RESOLUTION MAGIC ANGLE SPINNING NUCLEAR MAGNETIC RESONANCE (HRMAS NMR) FOR STUDIES OF REACTIVE FABRICS David J. McGarvey...unlimited. 13. SUPPLEMENTARY NOTES 14. ABSTRACT An analytical chemistry method is described for measuring the reactivity and permeation of

  13. Chiral vibrations and collective bands in 104Mo

    Science.gov (United States)

    Musangu, Brooks; Wang, E. H.; Zachary, C. J.; Eldridge, J. H.; Hamilton, J. H.; Ramayya, A. V.; Rasmussen, J. O.; Luo, Y. X.; Ter-Akopian, G. M.; Oganessian, Yu. Ts.; Zhu, S. J.

    2016-09-01

    High spin states of the neutron-rich 104Mo nucleus which is known to be triaxial have been reinvestigated by analyzing the γ-rays in the spontaneous fission of 252Cf with Gammasphere. Both γ- γ- γ and γ- γ- γ- γ coincidence data were analyzed. A new ΔI=1 band has been discovered. The new band is proposed to have a tentative 5- band head and form a class of chiral doublets with another 4- band previously found by our group. Angular correlation measurements have been performed to determine spin and parity of the 4- chiral band head. The energies of the two sets of chiral bands are very similar to the chiral bands observed in 106Mo, e.g. the two 5- levels in 104Mo are at 2211.9 and 2276.8 keV with ΔE=65 keV and in 106Mo, 1952.4 and 2090.6 keV with ΔE=138 keV. Now at every spin 5-, 6-, 7-, 8-, the separation energies of the same spin states are about a factor of two smaller than in 106Mo. This indicates even better agreement with expectations for two sets of chiral bands. Furman Advantage, Furman University.

  14. High Performance Ka-band Phase Shifters for Space Telecommunications Project

    Data.gov (United States)

    National Aeronautics and Space Administration — We propose a novel MEMS-based digital phase shifter targeted for Ka-band operation, but scalable down to X-band and up to W-band. This novel phase shifter will...

  15. Unconventional normal-state spin dynamics in underdoped high-Tc cuprates as a fingerprint of spiral correlations of localized spins and dual localized/itinerant nature of spin fluctuations

    Science.gov (United States)

    Onufrieva, F.

    2017-03-01

    The paper is motivated by the observation of unusual and not well understood spin dynamics in low- and moderately doped high-Tc cuprates as well as by the discovery in these materials of a static incommensurate order for doping exceeding the insulator-metal boundary in the phase diagram. We develop a microscopic approach that allows us to treat accurately the quantum fluctuations in the spiral state developing upon doping the Mott-Neel insulator. We show that the spiral order of localized spins induces an off-diagonal order of mobile charges and a gap Δ ∝|Q | in their spectrum (Q is the spiral incommensurability wave vector defined with respect to QAF). Due to the dynamic spin-charge interaction the latter gap produces a feedback effect consisting in the appearence of a gap in the coherent spin excitation spectrum. As a result, the characteristic energy ωc=Δ appears, in the spin excitation spectra. It separates two components with qualitatively different behavior-above ωc, spin excitations are magnonlike and have an upward dispersion, below it, they are of the relaxation type and have a slight downward dispersion. The form of the dispersion is close to the form observed experimentally (by inelastic neutron scattering), which can be characterized as OPEN-hour-glass shaped or Y -shaped. There is no qualitative difference between the spin dynamics in the normal and SC states as far as doping is relatively low. There is no resonance. Other important features, including the incommensurability and uniaxial anisotropy of the low-energy spin excitations and the doping dependencies of the characteristic energy and wave vectors, are also close to those observed experimentally in low-doped cuprates. We show that the static spiral state becomes unstable at the critical doping nc. We show also that adopting the hypothesis about the presence of finite-energy spiral correlations in the paramagnetic state above nc and based on the results obtained for the static spiral state

  16. High-pressure, high-temperature magic angle spinning nuclear magnetic resonance devices and processes for making and using same

    Science.gov (United States)

    Hu, Jian Zhi; Hu, Mary Y.; Townsend, Mark R.; Lercher, Johannes A.; Peden, Charles H. F.

    2015-10-06

    Re-usable ceramic magic angle spinning (MAS) NMR rotors constructed of high-mechanic strength ceramics are detailed that include a sample compartment that maintains high pressures up to at least about 200 atmospheres (atm) and high temperatures up to about least about 300.degree. C. during operation. The rotor designs minimize pressure losses stemming from penetration over an extended period of time. The present invention makes possible a variety of in-situ high pressure, high temperature MAS NMR experiments not previously achieved in the prior art.

  17. High-pressure, high-temperature magic angle spinning nuclear magnetic resonance devices and processes for making and using same

    Energy Technology Data Exchange (ETDEWEB)

    Hu, Jian Zhi; Hu, Mary Y.; Townsend, Mark R.; Lercher, Johannes A.; Peden, Charles H. F.

    2015-10-06

    Re-usable ceramic magic angle spinning (MAS) NMR rotors constructed of high-mechanic strength ceramics are detailed that include a sample compartment that maintains high pressures up to at least about 200 atmospheres (atm) and high temperatures up to about least about 300.degree. C. during operation. The rotor designs minimize pressure losses stemming from penetration over an extended period of time. The present invention makes possible a variety of in-situ high pressure, high temperature MAS NMR experiments not previously achieved in the prior art.

  18. High Power Test on an x-Band Slotted-Iris Accelerator Structure at NLCTA

    CERN Document Server

    Adolphsen, C; Fandos, R; Grudiev, A; Heikkinen, S; Laurent, L; Rodríguez, José Alberto; Taborelli, M; Wuensch, W

    2007-01-01

    The CLIC study group at CERN has built two X-band HDS (Hybrid Damped Structure) accelerating structures for high-power testing in NLCTA at SLAC. These accelerating structures are novel with respect to their rf-design and their fabrication technique. The eleven-cell constant impedance structures, one made out of copper and one out of molybdenum, are assembled from clamped high-speed milled quadrants. They feature the same heavy higher-order-mode damping as nominal CLIC structures achieved by slotted irises and radial damping waveguides for each cell. The X-band accelerators are exactly scaled versions of structures tested at 30 GHz in the CLIC test facility, CTF3. The results of the X-band tests are presented and compared to those at 30 GHz to determine frequency scaling, and are compared to the extensive copper data from the NLC structure development program to determine material dependence and make a basic validation of the HDS design. INTRODUCTION

  19. High-speed gel-spinning of ultra-high molecular weight polyethylene

    NARCIS (Netherlands)

    Pennings, A.J.; Hooft, R.J. van der; Postema, A.R.; Hoogsteen, W.; Brinke, G. ten

    1986-01-01

    This communication is concerned with the gel-spinning of ultrahigh molecular weight polyethylene (UHMWPE) at speeds up to 1500 m/min. It was found that 5 wt% solutions of UHMWPE in paraffin oil could be extruded through a conical die at a rate of 100 m/min. without the appearance of filament irregul

  20. High-efficiency Resonant rf Spin Rotator with Broad Phase Space Acceptance for Pulsed Polarized Cold Neutron Beams

    Energy Technology Data Exchange (ETDEWEB)

    Seo, P. -N. [Los Alamos National Laboratory (LANL); Barron-Palos, L. [Arizona State University; Bowman, J. D. [Los Alamos National Laboratory (LANL); Chupp, T. E. [University of Michigan; Crawford, C. [University of Tennessee, Knoxville (UTK); Dabaghyan, M. [University of New Hampshire; Dawkins, M. [Indiana University; Freedman, S. J. [University of California; Gentile, T. R. [National Institute of Standards and Technology (NIST); Gericke, M. T. [University of Manitoba, Canada; Gillis, R. C. [University of Manitoba, Canada; Greene, G. L. [University of Tennessee, Knoxville (UTK) & Oak Ridge National Laboratory (ORNL); Hersman, F. W. [University of New Hampshire; Jones, G. L. [Hamilton College, New York; Kandes, M. [University of Michigan; Lamoreaux, S. [Los Alamos National Laboratory (LANL); Lauss, B. [University of California, Berkeley; Leuschner, M. B. [Indiana University; Mahurin, R. [University of Tennessee, Knoxville (UTK); Mason, M. [University of New Hampshire; Mei, J. [Indiana University; Mitchell, G. S. [Los Alamos National Laboratory (LANL); Nann, H. [Indiana University; Page, S. A. [University of Manitoba, Canada; Penttila, S. I. [Los Alamos National Laboratory (LANL); Ramsay, W. D. [University of Manitoba & TRIUMF, Canada; Salas Bacci, A. [Los Alamos National Laboratory (LANL); Santra, S. [Indiana University; Sharma, M. [University of Michigan; Smith, T. B. [University of Dayton, Ohio; Snow, W. [Indiana University; Wilburn, W. S. [Los Alamos National Laboratory (LANL); Zhu, H. [University of New Hampshire

    2008-01-01

    High precision fundamental neutron physics experiments have been proposed for the intense pulsed spallation neutron beams at JSNS, LANSCE, and SNS to test the standard model and search for new physics. Certain systematic effects in some of these experiments have to be controlled at the few ppb level. The NPD Gamma experiment, a search for the small parity-violating {gamma}-ray asymmetry A{sub Y} in polarized cold neutron capture on parahydrogen, is one example. For the NPD Gamma experiment we developed a radio-frequency resonant spin rotator to reverse the neutron polarization in a 9.5 cm x 9.5 cm pulsed cold neutron beam with high efficiency over a broad cold neutron energy range. The effect of the spin reversal by the rotator on the neutron beam phase space is compared qualitatively to rf neutron spin flippers based on adiabatic fast passage. We discuss the design of the spin rotator and describe two types of transmission-based neutron spin-flip efficiency measurements where the neutron beam was both polarized and analyzed by optically polarized {sup 3}He neutron spin filters. The efficiency of the spin rotator was measured at LANSCE to be 98.8 {+-} 0.5% for neutron energies from 3 to 20 meV over the full phase space of the beam. Systematic effects that the rf spin rotator introduces to the NPD Gamma experiment are considered.

  1. High Efficiency Ka-Band Solid State Power Amplifier Waveguide Power Combiner

    Science.gov (United States)

    Wintucky, Edwin G.; Simons, Rainee N.; Chevalier, Christine T.; Freeman, Jon C.

    2010-01-01

    A novel Ka-band high efficiency asymmetric waveguide four-port combiner for coherent combining of two Monolithic Microwave Integrated Circuit (MMIC) Solid State Power Amplifiers (SSPAs) having unequal outputs has been successfully designed, fabricated and characterized over the NASA deep space frequency band from 31.8 to 32.3 GHz. The measured combiner efficiency is greater than 90 percent, the return loss greater than 18 dB and input port isolation greater than 22 dB. The manufactured combiner was designed for an input power ratio of 2:1 but can be custom designed for any arbitrary power ratio. Applications considered are NASA s space communications systems needing 6 to 10 W of radio frequency (RF) power. This Technical Memorandum (TM) is an expanded version of the article recently published in Institute of Engineering and Technology (IET) Electronics Letters.

  2. Lifetimes of high-spin states in {sup 180-184}Pt

    Energy Technology Data Exchange (ETDEWEB)

    Carpenter, M.P.; Ahmad, I.; Crowell, B. [and others

    1995-08-01

    Over the past few years, lifetimes were measured, using the recoil distance method, to investigate shape-coexistence and shape transitions in the even mass {sup 182-186}Pt isotopes. In all three cases, one observes a sharp increase in the transition quadrupole moment, Q{sub t}, at low frequencies followed by a rapid and significant decline in the backbending region. It was shown that the initial increase in the Q{sub t} can be explained in terms of the mixing at low spins of two bands of very different deformation, and the decline in the backbending region is brought about by mixing between the ground and a two-quasiparticle band. No lifetime information exists for these nuclei above the backbend, and there is some contention whether or not the backbend is due to the alignment of h{sub 9/2} protons, i{sub 13/2} neutrons or the near simultaneous alignment of both. Nilsson-Strutinsky calculations indicate very different shapes for the nuclei after the backbend, depending on which orbitals align. Thus, lifetime information on the states above the backbend should help determine which interpretation is correct. In order to determine the lifetimes of states in the even mass {sup 180-184}Pt nuclei above the backbend, we performed a recent experiment at Gammasphere using a {sup 64}Ni beam on Pb backed Sn targets in order to populate the nucleus of interest via a 4n reaction. At the time of the experiment, thirty-six Ge detectors were available for use in Gammasphere and approximately 100 x 10{sup 6} 3-fold and higher events were taken for each nucleus. Currently, angle-sorted matrices were created from the data, and spectra representing the ground bands show well developed lineshapes for transitions above the backbend. A full lineshape analysis of the data will begin shortly.

  3. Wide Frequency Band Active Damping Strategy for DFIG System High Frequency Resonance

    DEFF Research Database (Denmark)

    Song, Yipeng; Blaabjerg, Frede

    2016-01-01

    As a popular renewable power generation solution, the Doubly Fed Induction Generator (DFIG) based wind power system may suffer from High Frequency Resonance (HFR) caused by the impedance interaction between the DFIG system and the parallel compensated weak network. A wide frequency band active...... damping strategy for DFIG system HFR, including a high-pass filter and a virtual resistance, is proposed in this paper. The advantages of this active damping strategy are, 1) no resonance frequency detection unit is required, thus the control complexity can be decreased; 2) no active damping parameters...

  4. W-Band Free Electron Laser for High Gradient Structure Research

    Science.gov (United States)

    Lidia, S. M.; Whittum, D. H.; Donohue, J. T.

    1997-05-01

    We discuss the use of a free electron laser in support of material stress studies of W-band high-gradient accelerating structures. We propose the use of the linear induction accelerator LELIA (CEA/CESTA, France) to generate a 1-kiloamp, 80-ns FWHM electron pulse. We present a design for a helical FEL TE_11 amplifier that will generate high peak power (100's MW) at 93 GHz. We support our design with analytical estimates of gain, and with numerical simulations of power and phase development.

  5. Microstructure-Fibre-Based Optical Parametric Amplification in Telecom Band with Ultra-High Gain Slope

    Institute of Scientific and Technical Information of China (English)

    ZHANG Wei; XIAO Li; ZHANG Lei; HUANG Yi-Dong; PENG Jiang-De

    2006-01-01

    @@ We report a microstructure-fibre-based parametric amplification experiment in telecom band with ultra-high gain slope. A peak on-off gain of 52.3 dB is achieved using 25 m high nonlinear microstructure fibre (MF) and only 5.3 W pump power. The parametric gain slope is up to 580dBW-1 km-1. From the experimental data, the linear coefficient of the MF is estimated to be about 66. 7 W-1 km-1. The experiment shows the great potential of MFs in practical fibre parametric amplifiers.

  6. GDR Feeding of the Highly-Deformed Band in 42Ca

    CERN Document Server

    Kmiecik, M; Styczen, J; Bednarczyk, P; Brekiesz, M; Grebosz, J; Lach, M; Meczynski, W; Zieblinski, M; Zuber, K; Bracco, A; Camera, F; Benzoni, G; Million, B; Leoni, S; Wieland, O; Herskind, B; Curien, D; Dubray, N; Dudek, J; Schunck, N; Mazurek, K

    2004-01-01

    The gamma-ray spectra from the decay of the GDR in the compound nucleus reaction 18O+28Si at bombarding energy of 105 MeV have been measured in an experiment using the EUROBALL IV and HECTOR arrays. The obtained experimental GDR strength function is highly fragmented, with a low energy (10 MeV) component, indicating a presence of a large deformation and Coriolis effects. In addition, the preferential feeding of the highly-deformed band in 42Ca by this GDR low energy component is observed.

  7. Efficient operation of a high-power {ital X}-band traveling wave tube amplifier

    Energy Technology Data Exchange (ETDEWEB)

    Wang, P.; Xu, Z.; Ivers, J.D.; Nation, J.A.; Naqvi, S.; Schachter, L. [Cornell University, Ithaca, New York 14853 (United States)

    1999-10-01

    We report experimental results demonstrating 54{percent} power conversion efficiency (43{percent} energy conversion efficiency), from a two-stage {ital X}-band traveling wave tube amplifier designed for high-power operation. The first stage of the amplifier is a 12-cm-long Boron Nitride dielectric section used to modulate the electron beam. The second stage consists of a long high-phase-velocity bunching section followed by a short low-phase-velocity output section. Output powers of up to 78 MW with narrow spectrum width were obtained with {approximately}700 kV, {approximately}200 A beam. {copyright} {ital 1999 American Institute of Physics.}

  8. High-field magnetic phase transitions and spin excitations in magnetoelectric LiNiPO4

    DEFF Research Database (Denmark)

    Toft-Petersen, Rasmus; Jensen, Jens; Jensen, Thomas Bagger Stibius;

    2011-01-01

    The magnetically ordered phases and spin dynamics of magnetoelectric LiNiPO4 have been studied in fields up to 17.3 T along the c axis. Using neutron diffraction, we show that a previously proposed linearly polarized incommensurate (IC) structure exists only for temperatures just below the Neel......, the spiral structure is found to lock in to a period of five crystallographic unit cells along the b axis. Based on the neutron-diffraction data, combined with detailed magnetization measurements along all three crystallographic axes, we establish the magnetic phase diagrams for fields up to 17.3 T along c...... the linear and elliptical polarization of the IC structure, and that a generalization of the spin-wave theory, assuming the random-phase approximation, accounts for the inelastic scattering data obtained in the commensurable uniform phase at fields below 12 T as well as those obtained in the high-field IC...

  9. High spin-polarization in ultrathin Co{sub 2}MnSi/CoPd multilayers

    Energy Technology Data Exchange (ETDEWEB)

    Galanakis, I., E-mail: galanakis@upatras.gr

    2015-03-01

    Half-metallic Co{sub 2}MnSi finds a broad spectrum of applications in spintronic devices either in the form of thin films or as spacer in multilayers. Using state-of-the-art ab-initio electronic structure calculations we exploit the electronic and magnetic properties of ultrathin Co{sub 2}MnSi/CoPd multilayers. We show that these heterostructures combine high values of spin-polarization at the Co{sub 2}MnSi spacer with the perpendicular magnetic anisotropy of binary compounds such as CoPd. Thus they could find application in spintronic/magnetoelectronic devices. - Highlights: • Ab-initio study of ultrathin Co{sub 2}MnSi/CoPd multilayers. • Large values of spin-polarization at the Fermi are retained. • Route for novel spintronic/magnetoelectronic devices.

  10. Dynamics of one-dimensional Heisenberg spin glasses in the high-field limit

    Science.gov (United States)

    Boukahil, A.; Huber, D. L.

    1994-08-01

    This paper reports the results of a study of the distribution and localization of the magnon modes in one-dimensional Heisenberg spin glasses with nearest-neighbor interactions. The analysis is limited to high fields and frequencies near the precession frequency. Both symmetric and asymmetric distributions of exchange interactions of the form P(J)~||J||-α (α<1) are treated in detail. The results of approximate calculations based on the coherent-exchange approximation are shown to be in good agreement with numerical data obtained by applying mode-counting techniques to arrays of 107 spins. Particular emphasis is placed on the qualitative differences in the behavior that arise depending on whether the average values of J-1 and J-2 are zero, nonzero, or infinite.

  11. Spin polarization in high density quark matter under a strong external magnetic field

    DEFF Research Database (Denmark)

    Tsue, Yasuhiko; Da Providência, João; Providência, Constança

    2016-01-01

    In high density quark matter under a strong external magnetic field, possible phases are investigated by using the two-flavor Nambu-Jona-Lasinio (NJL) model with tensor-type four-point interaction between quarks, as well as the axial-vector-type four-point interaction. In the tensor......-type interaction under the strong external magnetic field, it is shown that a quark spin polarized phase is realized in all regions of the quark chemical potential under consideration within the lowest Landau level approximation. In the axial-vector-type interaction, it is also shown that the quark spin polarized...... phase appears in the wide range of the quark chemical potential. In both the interactions, the quark mass in zero and small chemical potential regions increases which indicates that the chiral symmetry breaking is enhanced, namely the magnetic catalysis occurs....

  12. Finding new superconductors: the spin-fluctuation gateway to high Tc and possible room temperature superconductivity.

    Science.gov (United States)

    Pines, David

    2013-10-24

    We propose an experiment-based strategy for finding new high transition temperature superconductors that is based on the well-established spin fluctuation magnetic gateway to superconductivity in which the attractive quasiparticle interaction needed for superconductivity comes from their coupling to dynamical spin fluctuations originating in the proximity of the material to an antiferromagnetic state. We show how lessons learned by combining the results of almost three decades of intensive experimental and theoretical study of the cuprates with those found in the decade-long study of a strikingly similar family of unconventional heavy electron superconductors, the 115 materials, can prove helpful in carrying out that search. We conclude that, since Tc in these materials scales approximately with the strength of the interaction, J, between the nearest neighbor local moments in their parent antiferromagnetic state, there may not be a magnetic ceiling that would prevent one from discovering a room temperature superconductor.

  13. Single Spin Asymmetries in High Energy Reactions and Nonperturbative QCD Effects

    CERN Document Server

    Dorokhov, A E; Nowak, W -D

    2009-01-01

    We discuss some experimental and theoretical results on single spin asymmetries (SSA) in high energy lepton-hadron and hadron-hadron reactions. In particular, recent results on meson SSA obtained by HERMES are considered in detail. We also discuss the SSA results obtained recently by COMPASS, as well as those from BRAHMS, PHENIX and STAR. Special attention is paid to a possible nonperturbative QCD mechanism that might be responsible for the observed meson SSA. This mechanism originates from the spin-flip quark-gluon chromomagnetic interaction induced by the complex topological structure of the QCD vacuum. We argue that in semi-inclusive deep-inelastic scattering a large SSA is expected not only for mesons but also for baryons due to strong nonperturbative final state interactions between $ud$-diquark and $u$-quark in the fragmenting proton.

  14. Observation of high spin levels in 131Cs from 131Ba decay

    Indian Academy of Sciences (India)

    M Sainath; Dwaraka Rani Rao; K Venkataramaniah; P C Sood

    2003-12-01

    The - and conversion electron spectra following 131Ba -decay are investigated, using HPGe detector and mini-orange electron spectrometer. Attention is particularly focussed on identifying weak transitions associated with low energy high spin levels in 131Cs level scheme earlier inferred in reaction studies but not yet observed in 131Ba decay. Our experiment identifies 15 new gammas and 6 new conversion lines in this decay. Internal conversion coefficients and multipolarities of several transitions are determined. Five new levels (3 with =7/2+ and one each with =9/2+ and 11/2-) are introduced in the 131Cs level scheme based on our observations taken together with the results from reaction studies. Spin-parity assignments to a few other levels are also suggested.

  15. Extreme deformations and clusterization at high spin in the A ~ 40 mass region

    Science.gov (United States)

    Ray, Debisree; Afanasjev, Anatoli

    2015-10-01

    Recent revival of the interest to the study of superdeformation and clusterization in light nuclei has motivated us to undertake the study of extreme deformations in the A ~ 32 - 50 N ~ Z nuclei. Unfortunately, at spin zero the predicted structures with extreme deformation are located at high excitation energies which prevents their experimental observation. On the other hand, the rotation brings such structures closer to the yrast line and, in principle, makes their observation possible with future generation of facilities such as GRETA. Thus, the systematic study of the extremely deformed structures and clusterization has been performed in the framework of cranked relativistic mean field theory. The major features of such structures, the spins at which they become yrast and the possiblities of their experimental observation will be discussed in this presentation. This work has been supported by the U.S. Department of Energy under the Grant DE-FG02-07ER41459.

  16. Simulating a High-Spin Black Hole-Neutron Star Binary

    Science.gov (United States)

    Derby, John; Lovelace, Geoffrey; Duez, Matt; Foucart, Francois; Simulating Extreme Spacetimes (SXS) Collaboration

    2017-01-01

    During their first observing run (fall 2015) Advanced LIGO detected gravitational waves from merging black holes. In its future observations LIGO could detect black hole neutron star binaries (BHNS). It is important to have numerical simulations to predict these waves, to help find as many of these waves as possible and to estimate the sources properties, because at times near merger analytic approximations fail. Also, numerical models of the disk formed when the black hole tears apart the neutron star can help us learn about these systems' potential electromagnetic counterparts. One area of the parameter space for BHNS systems that is particularly challenging is simulations with high black hole spin. I will present results from a new BHNS simulation that has a black hole spin of 90% of the theoretical maximum. We are part of SXS but not all.

  17. Electron Spin Pairing and the Phase Diagram of High-Tc Superconductors

    Institute of Scientific and Technical Information of China (English)

    GUO Wei; HAN Ru-Shan

    2001-01-01

    The origin of the instability of the normal state of electrons in the superconducting copper oxides is shown by the K-J model, in which the superexchange (K) between local moments and the Kondo exchange ( J) between electron and local moment are considered. The suppression of superexchange via impurity doping may induce effective spin coupling between electrons and triplet pairing (S = 1, Sz = 0). The spin pairing theory explains the phase diagram of high-To superconductors, especially the superconducting transition temperature Tc, the pseudogap temperature T* and the magnetic crossover temperature Tn as a function of the doped hole concentration. The universal expression for the empirical law of the superconducting transition temperature is derived from the theory.

  18. Equation-of-motion coupled cluster method for the description of the high spin excited states

    Science.gov (United States)

    Musiał, Monika; Lupa, Łukasz; Kucharski, Stanisław A.

    2016-04-01

    The equation-of-motion (EOM) coupled cluster (CC) approach in the version applicable for the excitation energy (EE) calculations has been formulated for high spin components. The EE-EOM-CC scheme based on the restricted Hartree-Fock reference and standard amplitude equations as used in the Davidson diagonalization procedure yields the singlet states. The triplet and higher spin components require separate amplitude equations. In the case of quintets, the relevant equations are much simpler and easier to solve. Out of 26 diagrammatic terms contributing to the R1 and R2 singlet equations in the case of quintets, only R2 operator survives with 5 diagrammatic terms present. In addition all terms engaging three body elements of the similarity transformed Hamiltonian disappear. This indicates a substantial simplification of the theory. The implemented method has been applied to the pilot study of the excited states of the C2 molecule and quintet states of C and Si atoms.

  19. Probing the dynamics of high-viscosity entangled polymers under shear using Neutron Spin Echo spectroscopy

    Science.gov (United States)

    Kawecki, M.; Gutfreund, P.; Adlmann, F. A.; Lindholm, E.; Longeville, S.; Lapp, A.; Wolff, M.

    2016-09-01

    Neutron Spin Echo spectroscopy provides unique insight into molecular and submolecular dynamics as well as intra- and inter-molecular interactions in soft matter. These dynamics may change drastically under shear flow. In particular in polymer physics a stress plateau is observed, which might be explained by an entanglement-disentanglement transition. However, such a transition is difficult to identify directly by experiments. Neutron Spin Echo has been proven to provide information about entanglement length and degree by probing the local dynamics of the polymer chains. Combining shear experiments and neutron spin echo is challenging since, first the beam polarisation has to be preserved during scattering and second, Doppler scattered neutrons may cause inelastic scattering. In this paper we present a new shear device adapted for these needs. We demonstrate that a high beam polarisation can be preserved and present first data on an entangled polymer solution under shear. To complement the experiments on the dynamics we present novel SANS data revealing shear- induced conformational changes in highly entangled polymers.

  20. Realization of the Haldane-Kane-Mele Model in a System of Localized Spins

    Science.gov (United States)

    Kim, Se Kwon; Ochoa, Héctor; Zarzuela, Ricardo; Tserkovnyak, Yaroslav

    2016-11-01

    We study a spin Hamiltonian for spin-orbit-coupled ferromagnets on the honeycomb lattice. At sufficiently low temperatures supporting the ordered phase, the effective Hamiltonian for magnons, the quanta of spin-wave excitations, is shown to be equivalent to the Haldane model for electrons, which indicates the nontrivial topology of the band and the existence of the associated edge state. At high temperatures comparable to the ferromagnetic-exchange strength, we take the Schwinger-boson representation of spins, in which the mean-field spinon band forms a bosonic counterpart of the Kane-Mele model. The nontrivial geometry of the spinon band can be inferred by detecting the spin Nernst effect. A feasible experimental realization of the spin Hamiltonian is proposed.