Bounds on the maximum attainable equilibrium spin polarization of protons at high energy in HERA

International Nuclear Information System (INIS)

Vogt, M.

2000-12-01

For some years HERA has been supplying longitudinally spin polarised electron and positron (e ± ) beams to the HERMES experiment and in the future longitudinal polarisation will be supplied to the II1 and ZEUS experiments. As a result there has been a development of interest in complementing the polarised e ± beams with polarised protons. In contrast to the case of e ± where spin flip due to synchrotron radiation in the main bending dipoles leads to self polarisation owing to an up-down asymmetry in the spin flip rates (Sokolov-Ternov effect), there is no convincing self polarisation mechanism for protons at high energy. Therefore protons must be polarised almost at rest in a source and then accelerated to the working energy. At HERA, if no special measures are adopted, this means that the spins must cross several thousand ''spin-orbit resonances''. Resonance crossing can lead to loss of polarisation and at high energy such effects are potentially strong since spin precession is very pronounced in the very large magnetic fields needed to contain the proton beam in HERA-p. Moreover simple models which have been successfully used to describe spin motion at low and medium energies are no longer adequate. Instead, careful numerical spin-orbit tracking simulations are needed and a new, mathematically rigorous look at the theoretical concepts is required. This thesis describes the underlying theoretical concepts, the computational tools (SPRINT) and the results of such a study. In particular strong emphasis is put on the concept of the invariant spin field and its non-perturbative construction. The invariant spin field is then used to define the amplitude dependent spin tune and to obtain numerical non-perturbative estimates of the latter. By means of these two key concepts the nature of higher order resonances in the presence of snakes is clarified and their impact on the beam polarisation is analysed. We then go on to discuss the special aspects of the HERA-p ring

Microscopic optical potential at medium energies

International Nuclear Information System (INIS)

Malecki, A.

1979-01-01

The problems concerning a microscopic optical model for the elastic nuclear collisions at medium energies are discussed. We describe the method for constructing the optical potential which makes use of the particular properties of quantum scattering in the eikonal limit. The resulting potential is expressed in terms of the nuclear wave functions and the nucleon-nucleon scattering amplitudes. This potential has a dynamic character since by including the effects of multiple scattering it allows for the possibility of intermediate excitations of the projectile and target nuclei. The use of the potential in the exact wave equation accounts for the most important mechanisms present in the collisions between composite particles. The microscopic optical model was successfully applied in the analysis of elastic scattering of protons and α-particles on atomic nuclei in the energy range of 300-1000 MeV/nucleon. The dynamic optical potential in this case represents a considerable improvement over the eikonal Glauber model and the static optical potential of Watson. The possibilities to extend the microscopic description of the proton-nucleus interaction by considering the spin dependence of the elementary amplitude and the Majorana exchange effects were investigated. (author)

Spin effects in high energy quark-quark scattering

International Nuclear Information System (INIS)

Goloskokov, S.V.; Selyugin, O.V.

1993-01-01

The spin amplitudes in high-energy quark-quark scattering at /t/>1 GeV 2 are analyzed. It is shown that the gluon contributions in the QCDα s 3 order lead to the spin-flip amplitude growing as s. This means the existence of the spin-flip part in pomeron exchange. The resulting T f is about few per cent of the spin-non-flip contribution. The factorization of the large-distance and high-energy effects in the spin-flip amplitude is obtained. 13 refs.; 2 figs.; 1 tab

Correlation functions of electronic and nuclear spins in a Heisenberg antiferromagnet semi-infinite medium

International Nuclear Information System (INIS)

Sarmento, E.F.

1981-01-01

Results are found for the dynamical correlation functions (or its corresponding Green's functions) among any combination including operator pairs of electronic and nuclear spins in an antiferromagnet semi-infinite medium, at low temperatures T [pt

Medium-Energy Particle experiments (MEPs) for the Exploration of energization and Radiation in Geospace (ERG) mission

Science.gov (United States)

Kasahara, S.; Yokota, S.; Mitani, T.; Asamura, K.; Hirahara, M.; Shibano, Y.; Yamamoto, K.; Takashima, T.

2017-12-01

ERG (Exploration of energization and Radiation in Geospace) is the geospace exploration spacecraft, which was launched on 20 December 2016. The mission goal is to unveil the physics behind the drastic radiation belt variability during space storms. One of key observations is the measurement of ions and electrons in the medium-energy range (10-200 keV), since these particles excite EMIC, magnetosonic, and whistler waves, which are theoretically suggested to play significant roles in the relativistic electron acceleration and loss. Medium-Energy Particle experiments - electron analyser (MEP-e) measures the energy and the direction of each incoming electron in the range of 7 to 87 keV. The sensor covers 2π radian disk-like field-of-view with 16 detectors, and the solid angle coverage is achieved by using spacecraft spin motion. The electron energy is independently measured by an electrostatic analyser and avalanche photodiodes, enabling the significant background reduction. Medium-Energy Particle experiments - ion mass analyzer (MEP-i) measures the energy, mass, and charge state of the direction of each incoming ion in the medium-energy range (180 keV/q). MEP-i thus provides the velocity distribution functions of medium-energy ions (e.g., protons and oxygens), from which we can obtain significant information on local ion energization and pitch angle scattering in the inner magnetosphere. Heavy ion measurements can also play an important role to restrict global mass transport including the ionosphere and the plasmasheet. Here we show the technical approaches, data output, and highlights of initial observations.

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...

High energy spin isospin modes in nuclei

International Nuclear Information System (INIS)

Chanfray, G.; Ericson, M.

1984-01-01

The high energy response of nuclei to a spin-isospin excitation is investigated. We show the existence of a strong contrast between the spin transverse and spin longitudinal responses. The second one undergoes a shadow effect in the Δ region and displays the occurrence of the pionic branch

Spinning fluids in general relativity

Science.gov (United States)

Ray, J. R.; Smalley, L. L.

1982-01-01

General relativity field equations are employed to examine a continuous medium with internal spin. A variational principle formerly applied in the special relativity case is extended to the general relativity case, using a tetrad to express the spin density and the four-velocity of the fluid. An energy-momentum tensor is subsequently defined for a spinning fluid. The equations of motion of the fluid are suggested to be useful in analytical studies of galaxies, for anisotropic Bianchi universes, and for turbulent eddies.

Medium energy ion scattering (MEIS)

International Nuclear Information System (INIS)

Dittmann, K.; Markwitz, A.

2009-01-01

This report gives an overview about the technique and experimental study of medium energy ion scattering (MEIS) as a quantitative technique to determine and analyse the composition and geometrical structure of crystalline surfaces and near surface-layers by measuring the energy and yield of the backscattered ions. The use of a lower energy range of 50 to 500 keV accelerated ions impinging onto the target surface and the application of a high-resolution electrostatic energy analyser (ESA) makes medium energy ion scattering spectroscopy into a high depth resolution and surface-sensitive version of RBS with less resulting damage effects. This report details the first steps of research in that field of measurement technology using medium energetic backscattered ions detected by means of a semiconductor radiation detector instead of an ESA. The study of medium energy ion scattering (MEIS) has been performed using the 40 keV industrial ion implanter established at GNS Sciences remodelled with supplementary high voltage insulation for the ion source in order to apply voltages up to 45 kV, extra apertures installed in the beamline and sample chamber in order to set the beam diameter accurately, and a semiconductor radiation detector. For measurement purposes a beam of positive charged helium ions accelerated to an energy of about 80 keV has been used impinging onto target surfaces of lead implanted into silicon (PbSi), scandium implanted into aluminium (ScAl), aluminium foil (Al) and glassy carbon (C). First results show that it is possible to use the upgraded industrial implanter for medium energy ion scattering. The beam of 4 He 2+ with an energy up to 88 keV has been focussed to 1 mm in diameter. The 5 nA ion beam hit the samples under 2 x 10 -8 mbar. The results using the surface barrier detector show scattering events from the samples. Cooling of the detector to liquid nitrogen temperatures reduced the electronic noise in the backscattering spectrum close to zero. A

Energy efficient hybrid computing systems using spin devices

Science.gov (United States)

Sharad, Mrigank

Emerging spin-devices like magnetic tunnel junctions (MTJ's), spin-valves and domain wall magnets (DWM) have opened new avenues for spin-based logic design. This work explored potential computing applications which can exploit such devices for higher energy-efficiency and performance. The proposed applications involve hybrid design schemes, where charge-based devices supplement the spin-devices, to gain large benefits at the system level. As an example, lateral spin valves (LSV) involve switching of nanomagnets using spin-polarized current injection through a metallic channel such as Cu. Such spin-torque based devices possess several interesting properties that can be exploited for ultra-low power computation. Analog characteristic of spin current facilitate non-Boolean computation like majority evaluation that can be used to model a neuron. The magneto-metallic neurons can operate at ultra-low terminal voltage of ˜20mV, thereby resulting in small computation power. Moreover, since nano-magnets inherently act as memory elements, these devices can facilitate integration of logic and memory in interesting ways. The spin based neurons can be integrated with CMOS and other emerging devices leading to different classes of neuromorphic/non-Von-Neumann architectures. The spin-based designs involve `mixed-mode' processing and hence can provide very compact and ultra-low energy solutions for complex computation blocks, both digital as well as analog. Such low-power, hybrid designs can be suitable for various data processing applications like cognitive computing, associative memory, and currentmode on-chip global interconnects. Simulation results for these applications based on device-circuit co-simulation framework predict more than ˜100x improvement in computation energy as compared to state of the art CMOS design, for optimal spin-device parameters.

Spin effects in medium-energy electron-3He scattering

International Nuclear Information System (INIS)

van den Brand, J.F.J.; Alarcon, R.; Bauer, T.

1998-01-01

New physics can be accessed by scattering polarized electrons from a polarized 3 He internal gas target. It is discussed how the asymmetries for the reactions 3 vector He(vector e,e'), 3 vector He(vector e,e'p), 3 vector He(vector e,e'n), 3 vector He(vector e,e'd), and 3 vector He(vector e,e'pn) may provide precise information on the S' and the D-wave parts of the 3 He ground-state wave function, the neutron form factors, and the role of spin-dependent reaction mechanism effects. The experiment uses up to 900 MeV (polarized) electrons from the AmPS storage ring in Amsterdam, Netherlands, in combination with large acceptance electron and hadron detectors. (orig.)

Rashba-Zeeman-effect-induced spin filtering energy windows in a quantum wire

International Nuclear Information System (INIS)

Xiao, Xianbo; Nie, Wenjie; Chen, Zhaoxia; Zhou, Guanghui; Li, Fei

2014-01-01

We perform a numerical study on the spin-resolved transport in a quantum wire (QW) under the modulation of both Rashba spin-orbit coupling (SOC) and a perpendicular magnetic field by using the developed Usuki transfer-matrix method in combination with the Landauer-Büttiker formalism. Wide spin filtering energy windows can be achieved in this system for unpolarized spin injection. In addition, both the width of energy window and the magnitude of spin conductance within these energy windows can be tuned by varying Rashba SOC strength, which can be apprehended by analyzing the energy dispersions and spin-polarized density distributions inside the QW, respectively. Further study also demonstrates that these Rashba-SOC-controlled spin filtering energy windows show a strong robustness against disorders. These findings may not only benefit to further understand the spin-dependent transport properties of a QW in the presence of external fields but also provide a theoretical instruction to design a spin filter device.

Rashba-Zeeman-effect-induced spin filtering energy windows in a quantum wire

Energy Technology Data Exchange (ETDEWEB)

Xiao, Xianbo, E-mail: xxb-11@hotmail.com; Nie, Wenjie [School of Computer, Jiangxi University of Traditional Chinese Medicine, Nanchang 330004 (China); Chen, Zhaoxia [School of Mechatronics Engineering, East China Jiaotong University, Nanchang 330013 (China); Zhou, Guanghui [Department of Physics and Key Laboratory for Low-Dimensional Quantum Structures and Manipulation (Ministry of Education), Hunan Normal University, Changsha 410081 (China); Li, Fei, E-mail: wltlifei@sina.com [Office of Scientific Research, Jiangxi University of Traditional Chinese Medicine, Nanchang 330004 (China)

2014-06-14

We perform a numerical study on the spin-resolved transport in a quantum wire (QW) under the modulation of both Rashba spin-orbit coupling (SOC) and a perpendicular magnetic field by using the developed Usuki transfer-matrix method in combination with the Landauer-Büttiker formalism. Wide spin filtering energy windows can be achieved in this system for unpolarized spin injection. In addition, both the width of energy window and the magnitude of spin conductance within these energy windows can be tuned by varying Rashba SOC strength, which can be apprehended by analyzing the energy dispersions and spin-polarized density distributions inside the QW, respectively. Further study also demonstrates that these Rashba-SOC-controlled spin filtering energy windows show a strong robustness against disorders. These findings may not only benefit to further understand the spin-dependent transport properties of a QW in the presence of external fields but also provide a theoretical instruction to design a spin filter device.

Development of global medium-energy nucleon-nucleus optical model potentials

International Nuclear Information System (INIS)

Madland, D.G.; Sierk, A.J.

1997-01-01

The authors report on the development of new global optical model potentials for nucleon-nucleus scattering at medium energies. Using both Schroedinger and Dirac scattering formalisms, the goal is to construct a physically realistic optical potential describing nucleon-nucleus elastic scattering observables for a projectile energy range of (perhaps) 20 meV to (perhaps) 2 GeV and a target mass range of 16 to 209, excluding regions of strong nuclear deformation. They use a phenomenological approach guided by conclusions from recent microscopic studies. The experimental database consists largely of proton-nucleus elastic differential cross sections, analyzing powers, spin-rotation functions, and total reaction cross sections, and neutron-nucleus total cross sections. They will use this database in a nonlinear least-squares adjustment of optical model parameters in both relativistic equivalent Schroedinger (including relativistic kinematics) and Dirac (second-order reduction) formalisms. Isospin will be introduced through the standard Lane model and a relativistic generalization of that model

Lagrangian dynamics of spinning particles and polarized media in general relativity

International Nuclear Information System (INIS)

Bailey, Ian.

1980-01-01

The dynamic laws governing spinning multipole test particles and polarized media with internal spin are derived from both variational principles and the multipole formalism of extended bodies. The general form of the Lagrangian equations of motion is derived for a spinning multipole particle in given external fields. The author then considers the dynamics of a continuous medium with internal spin and multipole structure. From a four-dimensional action integral the field equations relating to fields generated by the medium to its bulk properties are derived, together with the balance laws expressing conservation of total four-momentum and spin. A natural splitting of the total energy-momentum tensor into matter and field parts is adopted that leads to a generalized Minkowski electromagnetic energy tensor. In both the electromagnetic and the gravitational field equations the source terms contain polarization contributions. It is shown that the multipole formalism may be used to formulate the same equations of motion, balance laws and decomposition of total energy-momentum as those resulting from variational principles

Joint energy and spinning reserve dispatching and pricing

International Nuclear Information System (INIS)

Rashidinejad, M.; Song, Y.-H.; Javidi Dasht-Bayaz, M.H.

2000-01-01

Unpredictable load demand variations, and also sudden generation interruption, may cause imbalance in power systems. To prevent any blackout and to reduce such total power imbalance, spinning reserve can provide electric power system ability to respond. Adequate amount of spinning reserve should be based on economy and risk as an optimal decision making. This paper uses Quadratic Programming (QP) method to solve Joint Energy and Spinning Reserve Dispatch (JESRD) problem and derives the optimal price of spinning reserve. In JESRD, Unserved Energy Cost (UEC) is considered as an Opportunity Cost of Spinning Reserve (OCSR). To distribute the System Reserve Requirements (SRR) among generation units, two different models, Fixed Reserve Percentage (FRP) or fixed allocation model and Non-Fixed Reserve Percentage (NFRP) or flexible allocation model has been investigated. Numerical results on a 5-bus test system and the 30-bus IEEE standard system, considering FRP and NFRP models are included. (author)

Medium energy measurements of N-N parameters. Progress in research, January 1, 1983-December 31, 1983

International Nuclear Information System (INIS)

1983-12-01

The aim of the experimental program is the determination of the nucleon-nucleon amplitudes at medium energy. Experiments described include D/sub SS/, D/sub LS/, D/sub SL/, D/sub LL/, and P for p-p elastic scattering, the measurement of polarization observables in ppvector → pvector π + nu and ppvector → ppvector π, and measurements of the spin rotation parameters for pvector d → pvector d elastic scattering at 496, 647, and 800 MeV. Also, progress on an energy dependent proton-carbon analyzing power fit is reported. Current approved LAMPF proposals are described and 1983 publications are listed

The nuclear spin response to intermediate energy protons and deuterons at low momentum transfer

International Nuclear Information System (INIS)

Baker, F.T.; Djalali, C.; Glashausser, C.; Lenske, H.; Love, W.G.; Tomasi-Gustafsson, E.; Wambach, J.

1997-01-01

Measurements of polarization transfer in the inelastic scattering of intermediate energy protons and deuterons have yielded a wealth of data on the spin response of nuclei. This work complements the well-known studies of Gamow-Teller strength in charge-exchange reactions. The emphasis here is on a consistent determination of the S=1, T=0 response, practical only with deuterons, and on the proper separation of S=0 and S=1 strength in proton spectra for appropriate comparison with sum rules. We concentrate on two nuclei, 40 Ca and 12 C, at momentum transfers below about 1 fm -1 and on excitations up to about 50 MeV. The continuum second random phase approximation provides the primary theoretical tool for calculating and interpreting the response in terms of properties of the nucleon-nucleon force inside the nuclear medium. The reaction mechanism is described by the DWIA, applied here to continuum proton scattering almost as rigorously as it is usually applied to low energy excitations. A new DWIA formalism for the description of spin observables in deuteron scattering is used. Comparison of the proton and deuteron data with each other and with RPA/DWIA calculations yields interesting insights into the current state of understanding of collectivity and the nuclear spin response. (orig.)

The inelastic scattering of medium energy {alpha} particles; Sur la diffusion inelastique des particules {alpha} a moyenne energie

Energy Technology Data Exchange (ETDEWEB)

Crut, M [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1960-07-01

The aim of this work is to find out what are the properties of the so-called 'anomalous states' in medium weight nuclei. These states preferentially excited in the inelastic scattering of medium energy charged particles have an excitation energy at about 4 MeV for nuclei with Z {<=} 29 and in the range 2-3 MeV for high Z nuclei. From a combination of angular distribution data in the elastic and inelastic scattering of 30 MeV {alpha} particles, and correlation data between inelastic {alpha} particles and deexcitation {gamma} rays, we show that for even-even nuclei, we can attribute spin 3 and parity minus to these 'anomalous states'. This is quite in agreement with the interpretation of these levels suggested by Lane as due to collective octupole oscillations. We give a resume of the theories used in the analysis of the data and a description of the experimental set-up. (author) [French] Le but de cette etude est de determiner les proprietes des niveaux dits 'anormalement excites' lors de la diffusion inelastique des particules chargees de moyenne energie sur des noyaux de masse moyenne et lourde. L'energie de ces niveaux est de l'ordre de 4 MeV pour les noyaux avec Z {<=} 29 et de 2 a 3 MeV pour les noyaux de Z plus eleve. De l'examen des courbes de distribution angulaire des particules {alpha} de 30 MeV diffusees elastiquement et inelastiquement, et de la correlation angulaire entre {alpha} excitant ces niveaux 'anormaux' et {gamma} de desexcitation, on deduit que, dans le cas des pair-pair, on peut attribuer a ces niveaux spin 3 et parite moins. Ceci renforce l'hypothese emise par Lane qui attribue ces niveaux a des oscillations octupolaires de la surface du noyau. On donne un apercu des theories utilisees dans l'analyse des resultats et une description des dispositifs experimentaux. (auteur)

In-medium scaling law and electron scattering from high-spin states in 208Pb

International Nuclear Information System (INIS)

Arias de Saavedra, F.; Lallena, A.M.

1994-01-01

The effects of the environment modifications in the structure of the low-lying high-spin states of 208 Pb are studied by analyzing how the in-medium scaling law works on the excitation energies, wave functions, and electron scattering form factors corresponding to these states. It is shown that the consideration of f π * in addition to the effective ρ-meson mass does not affect too much most of the states analyzed. However, some of them appear to be extremely sensitive to its inclusion in the residual nucleon-nucleon interaction. As a result, a value of m ρ * /m ρ ∼f π * /f π ∼0.91 gives a good description of the (e,e') form factors of these particular states without any quenching factor. This value is in agreement with the one found for 48 Ca in a similar analysis performed in a previous work

Spin-neurons: A possible path to energy-efficient neuromorphic computers

Energy Technology Data Exchange (ETDEWEB)

Sharad, Mrigank; Fan, Deliang; Roy, Kaushik [School of Electrical and Computer Engineering, Purdue University, West Lafayette, Indiana 47907 (United States)

2013-12-21

Recent years have witnessed growing interest in the field of brain-inspired computing based on neural-network architectures. In order to translate the related algorithmic models into powerful, yet energy-efficient cognitive-computing hardware, computing-devices beyond CMOS may need to be explored. The suitability of such devices to this field of computing would strongly depend upon how closely their physical characteristics match with the essential computing primitives employed in such models. In this work, we discuss the rationale of applying emerging spin-torque devices for bio-inspired computing. Recent spin-torque experiments have shown the path to low-current, low-voltage, and high-speed magnetization switching in nano-scale magnetic devices. Such magneto-metallic, current-mode spin-torque switches can mimic the analog summing and “thresholding” operation of an artificial neuron with high energy-efficiency. Comparison with CMOS-based analog circuit-model of a neuron shows that “spin-neurons” (spin based circuit model of neurons) can achieve more than two orders of magnitude lower energy and beyond three orders of magnitude reduction in energy-delay product. The application of spin-neurons can therefore be an attractive option for neuromorphic computers of future.

Medium properties and total energy coupling in underground explosions

International Nuclear Information System (INIS)

Kurtz, S.R.

1975-01-01

A phenomenological model is presented that allows the direct calculation of the effects of variations in medium properties on the total energy coupling between the medium and an underground explosion. The model presented is based upon the assumption that the shock wave generated in the medium can be described as a spherical blast wave at early times. The total energy coupled to the medium is then simply the sum of the kinetic and internal energies of this blast wave. Results obtained by use of this model indicate that the energy coupling is more strongly affected by the medium's porosity than by its water content. These results agree well with those obtained by summing the energy deposited by the blast wave as a function of range

Experimental study of high spin states in low-medium mass nuclei by use of charge particle induced reactions

International Nuclear Information System (INIS)

Alenius, N.G.

1975-01-01

For the test of nuclear models the study of the properties of nuclear states of high angular momentum is especially important, because such states can often be given very simple theoretical descriptions. High spin states are easily populated by use of reactions initiated by alpha particles or heavy ions. In this thesis a number of low-medium mass nuclei have been studied, with emphasis on high spin states. (Auth.)

Theoretical studies in medium-energy nuclear and hadronic physics

International Nuclear Information System (INIS)

Horowitz, C.J.; Macfarlane, M.H.; Matsui, T.; Serot, B.D.

1993-01-01

A proposal for theoretical nuclear physics research is made for the period April 1, 1993 through March 31, 1996. Research is proposed in the following areas: relativistic many-body theory of nuclei and nuclear matter, quasifree electroweak scattering and strange quarks in nuclei, dynamical effects in (e,e'p) scattering at large momentum transfer, investigating the nucleon's parton sea with polarized leptoproduction, physics of ultrarelativistic nucleus endash nucleus collisions, QCD sum rules and hadronic properties, non-relativistic models of nuclear reactions, and spin and color correlations in a quark-exchange model of nuclear matter. Highlights of recent research, vitae of principal investigators, and lists of publications and invited talks are also given. Recent research dealt primarily with medium-energy nuclear physics, relativistic theories of nuclei and the nuclear response, the nuclear equation of state under extreme conditions, the dynamics of the quark endash gluon plasma in relativistic heavy-ion collisions, and theories of the nucleon endash nucleon force

Medium energy inelastic proton-nucleus scattering with spin dependent NN interaction

International Nuclear Information System (INIS)

Ahmad, I.; Auger, J.P.

1981-12-01

The previously proposed effective profile expansion method for the Glauber multiple scattering model calculation has been extended to the case of proton-nucleus inelastic scattering with spin dependent NN interaction. Using the method which turns out to be computationally simple and of relatively wider applicability, a study of sensitivity of proton-nucleus inelastic scattering calculation to the sometimes neglected momentum transfer dependence of the NN scattering amplitude has been made. We find that the calculated polarization is particularly sensitive in this respect. (author)

Heavy quark energy loss in nuclear medium

International Nuclear Information System (INIS)

Zhang, Benr-Wei; Wang, Enke; Wang, Xin-Nian

2003-01-01

Multiple scattering, modified fragmentation functions and radiative energy loss of a heavy quark propagating in a nuclear medium are investigated in perturbative QCD. Because of the quark mass dependence of the gluon formation time, the medium size dependence of heavy quark energy loss is found to change from a linear to a quadratic form when the initial energy and momentum scale are increased relative to the quark mass. The radiative energy loss is also significantly suppressed relative to a light quark due to the suppression of collinear gluon emission by a heavy quark

Summary of the 9th international symposium on high energy spin-physics

International Nuclear Information System (INIS)

Prescott, C.Y.

1990-11-01

Summarizing an international conference in high energy spin physics is never an easy task, because of the wide-ranging subjects in physics and technology that are involved. I have chosen to organize the topics of this conference into three broad categories relating to spin; intrinsic spin; composite spin; and spin, the experimental tool. In the first category, I will briefly revisit some historical and recent developments to set a background. In the second category, composite spin, I will discuss the status and developments in several areas, including magnetic moments of baryons, hyperon polarization in high energy high p perpendicular production, transverse polarization and asymmetries from transversely polarized targets in high p perpendicular scattering, spin structure of the proton, and the Bjorken sum rule. In the third category, I will discuss the steady, and at times rapid, progress in spin technology. In this part I include recent progress in high energy facilities, and comment on the highlights of the Workshops

Coordination of bidding strategies in day-ahead energy and spinning reserve markets

International Nuclear Information System (INIS)

Fushuan Wen; David, A.K.

2002-01-01

In this paper, the problem of building optimally coordinated bidding strategies for competitive suppliers in day-ahead energy and spinning reserve markets is addressed. It is assumed that each supplier bids 24 linear energy supply functions and 24 linear spinning reserve supply functions, one for each hour, into the energy and spinning reserve markets, respectively, and each market is cleared separately and simultaneously for all the 24 delivery hours. Each supplier makes decisions on unit commitment and chooses the coefficients in the linear energy and spinning reserve supply functions to maximise total benefits, subject to expectations about how rival suppliers will bid in both markets. Two different bidding schemes have been suggested for each hour, and based on them an overall coordinated bidding strategy in the day-ahead energy and spinning reserve market is then developed. Stochastic optimisation models are first developed to describe these two different bidding schemes and a genetic algorithm (GA) is then used to build the optimally coordinated bidding strategies for each scheme and to develop an overall bidding strategy for the day-ahead energy and spinning reserve markets. A numerical example is utilised to illustrate the essential features of the method. (Author)

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.

On the TAP Free Energy in the Mixed p-Spin Models

Science.gov (United States)

Chen, Wei-Kuo; Panchenko, Dmitry

2018-05-01

Thouless et al. (Phys Mag 35(3):593-601, 1977), derived a representation for the free energy of the Sherrington-Kirkpatrick model, called the TAP free energy, written as the difference of the energy and entropy on the extended configuration space of local magnetizations with an Onsager correction term. In the setting of mixed p-spin models with Ising spins, we prove that the free energy can indeed be written as the supremum of the TAP free energy over the space of local magnetizations whose Edwards-Anderson order parameter (self-overlap) is to the right of the support of the Parisi measure. Furthermore, for generic mixed p-spin models, we prove that the free energy is equal to the TAP free energy evaluated on the local magnetization of any pure state.

Spin effects in the screening and Auger neutralization of He+ ions in a spin-polarized electron gas

International Nuclear Information System (INIS)

Alducin, M.; Diez Muino, R.; Juaristi, J.I.

2005-01-01

The screening of a He + ion embedded in a free electron gas is studied for different spin-polarizations of the medium. Density functional theory and the local spin density approximation are used to calculate the induced electronic density for each spin orientation, i.e. parallel or antiparallel to the spin of the electron bound to the ion. Since both the He + ion and the electron gas are spin-polarized, we analyze in detail the spin state of the screening cloud for the two different possibilities: the spin of the bound electron can be parallel to either the majority spin or the minority spin in the medium. Finally, the spin-dependent Kohn-Sham orbitals are used to calculate the Auger neutralization rate of the He + ion. The polarization of the Auger excited electron is influenced by the spin-polarization of the medium. The results are discussed in terms of the spin-dependent screening and the indistinguishability of electrons with the same spin state

Modeling the neutron spin-flip process in a time-of-flight spin-resonance energy filter

CERN Document Server

Parizzi, A A; Klose, F

2002-01-01

A computer program for modeling the neutron spin-flip process in a novel time-of-flight (TOF) spin-resonance energy filter has been developed. The software allows studying the applicability of the device in various areas of spallation neutron scattering instrumentation, for example as a dynamic TOF monochromator. The program uses a quantum-mechanical approach to calculate the local spin-dependent spectra and is essential for optimizing the magnetic field profiles along the resonator axis. (orig.)

Overview of spin physics

International Nuclear Information System (INIS)

Yokosawa, A.

1992-01-01

Spin physics activities at medium and high energies became significantly active when polarized targets and polarized beams became accessible for hadron-hadron scattering experiments. My overview of spin physics will be inclined to the study of strong interaction using facilities at Argonne ZGS, Brookhaven AGS (including RHIC), CERN, Fermilab, LAMPF, an SATURNE. In 1960 accelerator physicists had already been convinced that the ZGS could be unique in accelerating a polarized beam; polarized beams were being accelerated through linear accelerators elsewhere at that time. However, there was much concern about going ahead with the construction of a polarized beam because (i) the source intensity was not high enough to accelerate in the accelerator, (ii) the use of the accelerator would be limited to only polarized-beam physics, that is, proton-proton interaction, and (iii) p-p elastic scattering was not the most popular topic in high-energy physics. In fact, within spin physics, π-nucleon physics looked attractive, since the determination of spin and parity of possible πp resonances attracted much attention. To proceed we needed more data beside total cross sections and elastic differential cross sections; measurements of polarization and other parameters were urgently needed. Polarization measurements had traditionally been performed by analyzing the spin of recoil protons. The drawbacks of this technique are: (i) it involves double scattering, resulting in poor accuracy of the data, and (ii) a carbon analyzer can only be used for a limited region of energy

Signature for g bosons from medium energy proton scattering experiments

International Nuclear Information System (INIS)

Kuyucak, S.

1993-01-01

We apply the recently developed algebraic (1/N expansion) scattering formalism to medium energy proton scattering from 154 Sm and 176 Yb. The nuclear structure effects in this formalism are described by the interacting boson model generalized to arbitrary interactions and types of bosons i.e. s,d,g, etc. We find that, in the sd boson model, a consistent description of cross sections is possible only for the 0 + and 2 + states. The failure of the model with regard to the 4 + states indicates that the effective hexadecapole operator used in the sd model is inadequate. In contrast, the data for scattering to the 0 + , 2 + and 4 + states could be consistently described in the sdg boson model. The spectroscopic data for the low-lying levels usually can not distinguish between the sd and sdg models due to renormalization of parameters, and one has to look at high spin or energy data for evidence of g bosons. The inelastic proton scattering experiments, on the other hand, directly probe the wave functions, and hence could provide a signature for g bosons even in the ground band states

High-spin states in 66Zn

International Nuclear Information System (INIS)

Bruandet, J.F.; Agard, M.; Giorni, A.; Longequeue, J.P.; Morand, C.; Tsan Ung Chan.

1975-01-01

The structure of 66 Zn has been investigated by studying the yield functions, angular distributions and coincidence relationships of the γ-rays emitted during bombardment of an enriched 64 Ni foil by α particles of medium energy 27MeV. Spins up to 10 h were assigned to observed states [fr

Efficiency of free-energy calculations of spin lattices by spectral quantum algorithms

International Nuclear Information System (INIS)

Master, Cyrus P.; Yamaguchi, Fumiko; Yamamoto, Yoshihisa

2003-01-01

Ensemble quantum algorithms are well suited to calculate estimates of the energy spectra for spin-lattice systems. Based on the phase estimation algorithm, these algorithms efficiently estimate discrete Fourier coefficients of the density of states. Their efficiency in calculating the free energy per spin of general spin lattices to bounded error is examined. We find that the number of Fourier components required to bound the error in the free energy due to the broadening of the density of states scales polynomially with the number of spins in the lattice. However, the precision with which the Fourier components must be calculated is found to be an exponential function of the system size

Centrifugal Spinning and Its Energy Storage Applications

Science.gov (United States)

Yao, Lu

-/micro-fiber production method to substitute electrospinning in industrial production. Recently, centrifugal spinning has gained researchers' attention. The centrifugal spinning method avoids the use of high voltage supply and can work with concentrated solutions, and most importantly, it can increase the production rate of nano-/micro-fibers to at least two orders or magnitude higher than that of electrospinning. This novel fiber fabrication approach is mostly used in tissue engineering field, and it can be potentially applied in preparing electrodes for SIBs and EDLCs. In the present work, we firstly study the influence of solution intrinsic properties and operational parameters using polyacrylonitrile as an example, and establish the processing-structure relationships for this spinning technique. We then use this novel spinning method to prepare porous carbon nanofibers (PCNFs), SnO2 microfibers and lithium-substituted sodium layered transition metal oxide fibers and use them as electrodes for EDLCs and SIBs. The as-prepared PCNFs, SnO2 microfibers and lithiumsubstituted sodium layered transition metal oxide fibers exhibit good electrochemical performance. It is therefore demonstrated that centrifugal spinning can be a promising nano- /micro-fiber preparation approach for mass production of electrode materials used in energy storage applications.

Spin observables at intermediate energies: a tool in viewing the nucleus

International Nuclear Information System (INIS)

McClelland, J.B.

1986-01-01

This paper attempts to summarize some of the advances made in intermediate nuclear physics through measurements of spin observables, notably in the range of bombarding energies from 100 to 1000 MeV. Relative to measurements of cross section, spin observables offer a highly selective filter in viewing the nucleus. Their general utility is found in their sensitivity to particular nuclear transitions and is further augmented by their simple connections to the NN force. The advantage of higher energies is apparent from the dominance of single-step mechanisms even at large energy losses where general nuclear spin responses may be made. Experimentally, this is an energy range where efficient, high-analyzing-power polarimeters can be coupled with high resolution detection techniques. 29 refs., 5 figs

Spin asymmetries for elastic scattering in krypton at intermediate energies

International Nuclear Information System (INIS)

Went, M R; McEachran, R P; Lohmann, Birgit; MacGillivray, W R

2002-01-01

Measurements of the spin asymmetry for elastic scattering of spin-polarized electrons from krypton are presented, for incident energies in the range 20-200 eV. The measured spin asymmetries are generally small, and do not exceed 0.25 in magnitude at any energy or angle. The experimental results are compared with calculated values of the Sherman function, obtained by solution of the Dirac-Fock equations. The calculations have been performed with the inclusion of polarization and dynamic distortion potentials, and with the addition of an absorption potential to model inelastic processes. For incident energies of 50, 60 and 65 eV, the calculated values of the Sherman function are shown to be extremely sensitive to the details of the model, with the addition of the absorption potential producing dramatically different results

Innovative spin precessor for intermediate energy protons

International Nuclear Information System (INIS)

Hoffman, E.W.

1979-01-01

A spin precessor has been designed to provide arbitrary orientation of the polarization in the external proton beam at LAMPF. The device utilizes two superconducting solenoids, three conventional dipoles, and conversion of polarized H - to H + to provide an achromatic, undeflected beam with tunable spin orientation over a range of energies from 400 MeV to 800 MeV. A portion of this device is being installed to provide compatibility between two facilities which simultaneously use two branches of the external proton beam at LAMPF

High-spin research with HERA [High Energy-Resolution Array

International Nuclear Information System (INIS)

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

Analysis of possibilities for a spin flip in high energy electron ring HERA

International Nuclear Information System (INIS)

Stres, S.; Pestotnik, R.

2007-01-01

In a high energy electron ring the spins of electrons become spontaneously polarized via the emission of spin-flip synchrotron radiation. By employing a radio frequency (RF) radial dipole field kicker, particle spin directions can be rotated slowly over many turns. A model which couples three dimensional spin motion and longitudinal particle motion was constructed to describe non-equilibrium spin dynamics in high energy electron storage rings. The effects of a stochastic synchrotron radiation on the orbital motion in the accelerator synchrotron plane and its influence on the spin motion are studied. The main contributions to the spin motion, the synchrotron oscillations and the stochastic synchrotron radiation, have different influence on the spin polarization reversal in different regions of the parameter space. The results indicate that polarization reversal might be obtained in high energy electron storage rings with a significant noise even with relatively small strengths of a perturbing magnetic field. The only experimental datum avaliable agrees with the model prediction, however further experimental data would be necessary to validate the model

Optically tunable spin-exchange energy at donor:acceptor interfaces in organic solar cells

International Nuclear Information System (INIS)

Li, Mingxing; Wang, Hongfeng; He, Lei; Zang, Huidong; Xu, Hengxing; Hu, Bin

2014-01-01

Spin-exchange energy is a critical parameter in controlling spin-dependent optic, electronic, and magnetic properties in organic materials. This article reports optically tunable spin-exchange energy by studying the line-shape characteristics in magnetic field effect of photocurrent developed from intermolecular charge-transfer states based on donor:acceptor (P3HT:PCBM) system. Specifically, we divide magnetic field effect of photocurrent into hyperfine (at low field   10 mT) regimes. We observe that increasing photoexcitation intensity can lead to a significant line-shape narrowing in magnetic field effect of photocurrent occurring at the spin-exchange regime. We analyze that the line-shape characteristics is essentially determined by the changing rate of magnetic field-dependent singlet/triplet ratio when a magnetic field perturbs the singlet-triplet transition through spin mixing. Based on our analysis, the line-shape narrowing results indicate that the spin-exchange energy at D:A interfaces can be optically changed by changing photoexcitation intensity through the interactions between intermolecular charge-transfer states. Therefore, our experimental results demonstrate an optical approach to change the spin-exchange energy through the interactions between intermolecular charge-transfer states at donor:acceptor interface in organic materials.

Spin-flip processes in low-energy Fe17+ + He collisions

International Nuclear Information System (INIS)

Bruch, R.; Altick, P.L.; Rauscher, E.; Wang, H.; Schneider, D.

1993-01-01

Spin-nonconserving electron transfer processes violating the ''Wigner rule'' have been studied for slow multiply charged ion-atom collisions. Experimentally a strong population of highly metastable sodium-like quartet states in low energy Fe 17+ + He single collision events has been observed. The possibility of double-electron capture plus spin-flip mechanisms has been discussed experimentally and theoretically, Our theoretical model using time dependent perturbation theory predicts that spin-flip processes are as likely as no spin flip under the conditions of our experiment

Low energy properties of the SU(m|n) supersymmetric Haldane-Shastry spin chain

International Nuclear Information System (INIS)

Basu-Mallick, B.; Bondyopadhaya, Nilanjan; Sen, Diptiman

2008-01-01

The ground state and low energy excitations of the SU(m|n) supersymmetric Haldane-Shastry spin chain are analyzed. In the thermodynamic limit, it is found that the ground state degeneracy is finite only for the SU(m|0) and SU(m|1) spin chains, while the dispersion relation for the low energy and low momentum excitations is linear for all values of m and n. We show that the low energy excitations of the SU(m|1) spin chain are described by a conformal field theory of m non-interacting Dirac fermions which have only positive energies; the central charge of this theory is m/2. Finally, for n≥1, the partition functions of the SU(m|n) Haldane-Shastry spin chain and the SU(m|n) Polychronakos spin chain are shown to be related in a simple way in the thermodynamic limit at low temperatures

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.

Spin structure in high energy processes: Proceedings

International Nuclear Information System (INIS)

DePorcel, L.; Dunwoodie, C.

1994-12-01

This report contains papers as the following topics: Spin, Mass, and Symmetry; physics with polarized Z 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 ( 3 HE) and the Bjoerken sum rule; a consumer's guide to lattice QCD results; top ten models constrained by b → 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

Energy levels and electron g-factor of spherical quantum dots with Rashba spin-orbit interaction

International Nuclear Information System (INIS)

Vaseghi, B.; Rezaei, G.; Malian, M.

2011-01-01

We have studied simultaneous effects of Rashba spin-orbit interaction and external electric and magnetic fields on the subbands energy levels and electron g-factor of spherical quantum dots. It is shown that energy eigenvalues strongly depend on the combined effects of external electric and magnetic fields and spin-orbit interaction strength. The more the spin-orbit interaction strength increase, the more the energy eigenvalues increase. Also, we found that the electron g-factor sensitively differers from the bulk value due to the confinement effects. Furthermore, external fields and spin-orbit interaction have a great influence on this important quantity. -- Highlights: → Energy of spherical quantum dots depends on the spin-orbit interaction strength in external electric and magnetic fields. → Spin-orbit interaction shifts the energy levels. → Electron g-factor differs from the bulk value in spherical quantum dots due to the confinement effects. → Electron g-factor strongly depends on the spin-orbit interaction strength in external electric and magnetic fields.

Zero-Magnetic-Field Spin Splitting of Polaron's Ground State Energy Induced by Rashba Spin-Orbit Interaction

International Nuclear Information System (INIS)

Liu Jia; Xiao Jingling

2006-01-01

We study theoretically the ground state energy of a polaron near the interface of a polar-polar semiconductor by considering the Rashba spin-orbit (SO) coupling with the Lee-Low-Pines intermediate coupling method. Our numerical results show that the Rashba SO interaction originating from the inversion asymmetry in the heterostructure splits the ground state energy of the polaron. The electron areal density and vector dependence of the ratio of the SO interaction to the total ground state energy or other energy composition are obvious. One can see that even without any external magnetic field, the ground state energy can be split by the Rashba SO interaction, and this split is not a single but a complex one. Since the presents of the phonons, whose energy gives negative contribution to the polaron's, the spin-splitting states of the polaron are more stable than electron's.

Energy-imbalance mechanism of domain wall motion induced by propagation spin waves in finite magnetic nanostripe

International Nuclear Information System (INIS)

Zhu, Jinrong; Han, Zhaoyan; Su, Yuanchang; Hu, Jingguo

2014-01-01

The mechanism of the domain wall (DW) motions induced by spin wave in finite magnetic nanostripe is studied by micromagnetic simulations. We find that the spin-wave induced DM motions are always accompanied by an energy imbalance between two sides of the DW. The DW motion can be attributed to the expansion of the low-energy-density area and the contraction of the high-energy-density area. The energy imbalance strongly depends on whether the spin wave passes through the DW or is reflected by the DW. In the area of the spin wave propagation, the energy density increases with the time. However, in the superposition area of the incident spin wave and the reflected spin wave, the energy density decreases with the increasing of the time. It shows that this energy imbalance can be controlled by tuning the frequency of the spin wave. Finally, the effect of the damping parameter value is discussed. - Highlights: • The mechanism of the spin-wave induced DW motions is studied. • The spin-wave induced DW motions and the energy imbalance mechanism are given. • The DW motion with the same direction to that of SW is explained. • The DW motion with the opposite direction to that of SW is explained

Spin observables in proton-neutron scattering at intermediate energy

International Nuclear Information System (INIS)

Spinka, H.

1986-05-01

A summary of np elastic scattering spin measurements at intermediate energy is given. Preliminary results from a LAMPF experiment to measure free neutron-proton elastic scattering spin-spin correlation parameters are presented. A longitudinally polarized proton target was used. These measurements are part of a program to determine the neutron-proton amplitudes in a model independent fashion at 500, 650, and 800 MeV. Some new proton-proton total cross sections in pure helicity states (Δσ/sub L/(pp)) near 3 GeV/c are also given. 37 refs., 2 figs

Nuclear spin and isospin excitations

International Nuclear Information System (INIS)

Osterfeld, F.

1992-01-01

A review is given of our present knowledge of collective spin-isospin excitations in nuclei. Most of this knowledge comes from intermediate-energy charge-exchange reactions and from inelastic electron- and proton-scattering experiments. The nuclear-spin dynamics is governed by the spin-isospin-dependent two-nucleon interaction in the medium. This interaction gives rise to collective spin modes such as the giant Gamow-Teller resonances. An interesting phenomenon is that the measured total Gamow-Teller transition strength in the resonance region is much less than a model-independent sum rule predicts. Two physically different mechanisms have been discussed to explain this so-called quenching of the total Gamow-Teller strength: coupling to subnuclear degrees of freedom in the form of Δ-isobar excitation and ordinary nuclear configuration mixing. Both detailed nuclear structure calculations and extensive analyses of the scattering data suggest that the nuclear configuration mixing effect is the more important quenching mechanism, although subnuclear degrees of freedom cannot be ruled out. The quenching phenomenon occurs for nuclear-spin excitations at low excitation energies (ω∼10--20 MeV) and small-momentum transfers (q≤0.5 fm -1 ). A completely opposite effect is anticipated in the high (ω,q)-transfer region (0≤ω≤500 MeV, 0.5≤q≤3 fm -1 ). The nuclear spin-isospin response might be enhanced due to the attractive pion field inside the nucleus. Charge-exchange reactions at GeV incident energies have been used to study the quasifree peak region and the Δ-resonance region. An interesting result of these experiments is that the Δ excitation in the nucleus is shifted downwards in energy relative to the Δ excitation of the free proton

Medium-energy charged-particle data for evaluation

International Nuclear Information System (INIS)

Pearlstein, S.

1989-01-01

Medium-energy charged particles incident on targets can cause a variety of nuclear reactions. Charged-particle transport calculations require access to a large body of cross-section data, which results in interest in an evaluated charged-particle data library. Developing an evaluated data library can involve several steps. An index to the literature on measurements and theory is useful to locate information relevant to data evaluation. A computerized compilation of measurements facilitates the intercomparison of different experiments and the determination of how well data are known. Nuclear models, based on theory or phenomenological evidence, are compared with experiment and, where validated, are used to fill in regions where experimental data are not available. Finally, the selected data are placed into computer-readable formats for use in transport calculations. Specialized indexes to bibliography help the scientist to keep up with his field and catch up with new subjects of interest. Several indexes are relevant to medium-energy nuclear data. In addition, these data are covered in several reports not issued on a regular basis. The technical area of medium-energy charged-particle data is maturing. From isolated measurements and theories, a comprehensive approach toward establishing a validated data base extending from low to high energies is emerging

Detailed EXOSAT and optical observations of the intermediate polar 3A0729+103: discovery of two medium energy X-ray emission regions

International Nuclear Information System (INIS)

McHardy, I.M.; Pye, J.P.; Fairall, A.P.; Menzies, J.W.

1987-01-01

EXOSAT observations of the intermediate polar cataclysmic variable 3A0729+103 reveal a strong orbital modulation, with the 2-4KeV X-rays being significantly more modulated than the 4-6keV X-rays, indicative of photoelectric absorption. The 913 second modulation which is very prominent in the optical light curve, is weakly detected in the medium-energy X-ray light curve, confirming that it represents the white dwarf spin period. These observations are well explained by a combination of two sources of medium-energy X-ray emission. The presence of two emission regions is also clearly seen in the optical spectroscopy, particularly in the intensity of the He II4686 line which has two peaks during the orbit. The authors identify the two optical emission regions with the two X-ray emission regions. (author)

Design and performance of a spin-polarized electron energy loss spectrometer with high momentum resolution

Energy Technology Data Exchange (ETDEWEB)

Vasilyev, D.; Kirschner, J. [Max-Planck-Institut für Mikrostrukturphysik, Weinberg 2, 06120 Halle (Germany)

2016-08-15

We describe a new “complete” spin-polarized electron energy loss spectrometer comprising a spin-polarized primary electron source, an imaging electron analyzer, and a spin analyzer of the “spin-polarizing mirror” type. Unlike previous instruments, we have a high momentum resolution of less than 0.04 Å{sup −1}, at an energy resolution of 90-130 meV. Unlike all previous studies which reported rather broad featureless data in both energy and angle dependence, we find richly structured spectra depending sensitively on small changes of the primary energy, the kinetic energy after scattering, and of the angle of incidence. The key factor is the momentum resolution.

Precompound decay models for medium energy nuclear reactions

International Nuclear Information System (INIS)

Blann, M.

1989-11-01

The formulations used for precompound decay models are presented and explained in terms of the physics of the intranuclear cascade model. Several features of spectra of medium energy (10--1000 MeV) reactions are summarized. Results of precompound plus evaporation calculations from the code ALICE are compared with a wide body of proton, alpha, and heavy ion induced reaction data to illustrate both the power and deficiencies of predicting yield of these reactions in the medium energy regime. 23 refs., 13 figs

Hadron photoproduction at medium energy

International Nuclear Information System (INIS)

Dainton, J.B.

1985-04-01

Results from measurements of multibody photoproduction at medium incident photon energy (2.8 to 4.8 GeV) are presented and discussed. Particular emphasis is placed on topics which are not well understood and which therefore motivate experiments with the upgraded electron accelerator and storage ring ELSA at the University of Bonn, FR Germany. (author)

Acceleration of polarized proton in high energy accelerators

International Nuclear Information System (INIS)

Lee, S.Y.

1991-01-01

In low to medium energy accelerators, betatron tune jumps and vertical orbit harmonic correction methods have been used to overcome the intrinsic and imperfection resonances. At high energy accelerators, snakes are needed to preserve polarization. The author analyzes the effects of snake resonances, snake imperfections, and overlapping resonances on spin depolarization. He discusses also results of recent snake experiments at the IUCF Cooler Ring. The snake can overcome various kinds of spin depolarization resonances. These experiments pointed out further that partial snake can be used to cure the imperfection resonances in low to medium energy accelerators

Electrically and magnetically controlled optical spanner based on the transfer of spin angular momentum of light in an optically active medium

International Nuclear Information System (INIS)

Chen Lixiang; Zheng Guoliang; She Weilong

2007-01-01

An optical spanner is a light beam that can exert a torque on an object. It is demonstrated in this Rapid Communication that, with the aid of applied electric and magnetic fields, a light beam with initially linear polarization and initially zero total spin angular momentum can interact with an optically active medium, resulting in a change of the ratio of left-handed circularly polarized photons to right-handed ones. Thus the total spin angular momentum of the light is changed, which leads to a torque, creating an electrically and magnetically controlled optical spanner on the medium. For a linearly polarized 632.8 nm laser beam incident on a 100-μm-long Ce:Bi 12 TiO 20 whisker crystal with 5 μm radius, if the magnetic field is fixed at -1.8 T, both the left- (right-)handed circularly polarized photon number and the total spin angular momentum vary with the applied electric field in a sinusoidal way, which means the torque exerted by the optical spanner on the crystal also varies sinusoidally with the electric field. It is found that at 50 (or-50) kV/cm, 56% right- (left-)handed circularly polarized photons are translated into left- (right-)handed ones, which corresponds to a transfer of 0.56(ℎ/2π) spin angular momentum contributed by each photon

Microscopic energy flows in disordered Ising spin systems

International Nuclear Information System (INIS)

Agliari, E; Casartelli, M; Vezzani, A

2010-01-01

An efficient microcanonical dynamics has been recently introduced for Ising spin models embedded in a generic connected graph even in the presence of disorder, i.e. with the spin couplings chosen from a random distribution. Such a dynamics allows a coherent definition of local temperatures also when open boundaries are coupled to thermostats, imposing an energy flow. Within this framework, here we introduce a consistent definition for local energy currents and we study their dependence on the disorder. In the linear response regime, when the global gradient between thermostats is small, we also define local conductivities following a Fourier discretized picture. Then, we work out a linearized 'mean-field approximation', where local conductivities are supposed to depend on local couplings and temperatures only. We compare the approximated currents with the exact results of the nonlinear system, showing the reliability range of the mean-field approach, which proves very good at high temperatures and not so efficient in the critical region. In the numerical studies we focus on the disordered cylinder but our results could be extended to an arbitrary, disordered spin model on generic discrete structures

Relationship between energy landscape and low-temperature dynamics of ±J spin glasses

International Nuclear Information System (INIS)

Kobe, S.; Krawczyk, J.

2004-01-01

Clusters and valleys in the exact low-energy landscape of finite Edwards-Anderson ±J spin glasses are related to the distribution of spin domains and free spins in the ground states. The time evolution of the spin correlation function reflects a walk through the landscape at a given temperature and shows typical glassy behaviour

Influence of primary fragment excitation energy and spin distributions on fission observables

Science.gov (United States)

Litaize, Olivier; Thulliez, Loïc; Serot, Olivier; Chebboubi, Abdelaziz; Tamagno, Pierre

2018-03-01

Fission observables in the case of 252Cf(sf) are investigated by exploring several models involved in the excitation energy sharing and spin-parity assignment between primary fission fragments. In a first step the parameters used in the FIFRELIN Monte Carlo code "reference route" are presented: two parameters for the mass dependent temperature ratio law and two constant spin cut-off parameters for light and heavy fragment groups respectively. These parameters determine the initial fragment entry zone in excitation energy and spin-parity (E*, Jπ). They are chosen to reproduce the light and heavy average prompt neutron multiplicities. When these target observables are achieved all other fission observables can be predicted. We show here the influence of input parameters on the saw-tooth curve and we discuss the influence of a mass and energy-dependent spin cut-off model on gamma-rays related fission observables. The part of the model involving level densities, neutron transmission coefficients or photon strength functions remains unchanged.

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.

A protocol describing the use of a recombinant protein-based, animal product-free medium (APEL) for human embryonic stem cell differentiation as spin embryoid bodies.

Science.gov (United States)

Ng, Elizabeth S; Davis, Richard; Stanley, Edouard G; Elefanty, Andrew G

2008-01-01

In order to promote the uniform and reproducible differentiation of human embryonic stem cells (HESCs) in response to exogenously added growth factors, we have developed a method (spin embryoid bodies (EBs)) that uses a recombinant protein-based, animal product-free medium in which HESCs are aggregated by centrifugation to form EBs. In this protocol we describe the formulation of this medium, denoted APEL (Albumin Polyvinylalcohol Essential Lipids), and its use in spin EB differentiation of HESCs. We also describe a more economical variant, BPEL (Bovine Serum Albumin (BSA) Polyvinylalchohol Essential Lipids), in which BSA replaces the recombinant human albumin. The integration of a medium that includes only defined and recombinant components with a defined number of cells to initiate EB formation results in a generally applicable, robust platform for growth factor-directed HESC differentiation.

Spin wave energy dispersion in KCuF/sub 3/: a nearly one-dimensional spin-1/2 antiferromagnet. [4. 7/sup 0/K

Energy Technology Data Exchange (ETDEWEB)

Hutchings, M T; Ikeda, H; Milne, J M

1979-09-28

Using inelastic neutron scattering techniques, the spin wave energy dispersion in the (010) plane of the distorted perovskite KCuF/sub 3/, which exhibits many magnetic properties of the spin-1/2 one-dimensional antiferromagnet, has been investigated at 4.7 K (T/sub N/ = 39 K). The measurements confirm the very strong exchange interaction between the spins in the (001) direction, and show that in this direction the expression for the excitation energies of the spin-1/2 antiferromagnetic chain given by J des Cloizeaux and J J Pearson is obeyed. The exchange interaction between these chains is found to be only 1.6% of that within the chains.

Gamma-ray astronomy in the medium energy (10-50 MeV) range

International Nuclear Information System (INIS)

Kniffen, D.A.; Bertsch, D.L.; Palmeira, R.A.R.; Rao, K.R.

1977-01-01

Gamma-ray astronomy in the medium energy (10-50 MeV) range can provide unique information with which to study many astrophysical problems. Observations in the 10-50 MeV range provide the cleanest window with which to view the isotropic diffuse component of the radiation and to study the possible cosmological implications of the spectrum. For the study of compact sources, this is the important region between the X-ray sky and the vastly different γ-ray sky seen by SAS-2 and COS-B. To understand the implications of medium energy γ-ray astronomy to the study of the galactic diffuse γ-radiation, the model developed to explain the high energy γ-ray observations of SAS-2 is extended to the medium energy range. This work illustrates the importance of medium energy γ-ray astronomy for studying the electromagnetic component of the galactic cosmic rays. To observe the medium energy component of the intense galactic center γ-ray emission, two balloon flights of a medium energy γ-ray spark chamber telescope were flown in Brazil in 1975. These results indicate the emission is higher than previously thought and above the predictions of the theoretical model

Medium-spin levels and the character of the 20.4 ns 13/2+ isomer in 145Gd

International Nuclear Information System (INIS)

Pakkanen, A.; Muhonen, J.; Piiparinen, M.

1981-06-01

Levels of the N = 81 nucleus 145 Gd have been investigated by in-beam γ-ray and conversion electron spectroscopy with the 144 Sm( 3 He,2n) reaction. Fourteen new low- and medium-spin states between 1.0 and 2.4 MeV excitation, the known yrast levels up to spin (21/2) + , five other high-spin non-yrast states and a new 20.4 ns (13/2) + isomer at 2200.2 keV in 145 Gd have been observed. The isomer decays via a fast 927.3 keV E3 transition with B(E3) = 48 +- 7 W.u. Another weaker decay branch is a mixed, strongly hindered E1+M2+E3 transition to the νhsub(11/2)sup(-1) state. We propose an octupole νfsub(7/2)jsub(0)sup(-2)x3 - main configuration for the isomer, analogous to the 997 keV (13/2) + isomer in 147 Gd. The levels of 145 Gd are discussed on the basis of the spherical shell model. (author)

Spin Polarization Oscillations without Spin Precession: Spin-Orbit Entangled Resonances in Quasi-One-Dimensional Spin Transport

Directory of Open Access Journals (Sweden)

D. H. Berman

2014-03-01

Full Text Available Resonant behavior involving spin-orbit entangled states occurs for spin transport along a narrow channel defined in a two-dimensional electron gas, including an apparent rapid relaxation of the spin polarization for special values of the channel width and applied magnetic field (so-called ballistic spin resonance. A fully quantum-mechanical theory for transport using multiple subbands of the one-dimensional system provides the dependence of the spin density on the applied magnetic field and channel width and position along the channel. We show how the spatially nonoscillating part of the spin density vanishes when the Zeeman energy matches the subband energy splittings. The resonance phenomenon persists in the presence of disorder.

Spin observables in inelastic proton-nucleus scattering at intermediate energy

International Nuclear Information System (INIS)

Smith, R.D.

1984-01-01

This dissertation is a study of spin observables in inelastic proton-nucleus reactions for incident proton energies near 1 GeV. At this energy, the dominant reaction mechanisms are (1) quasi-free knockout of one or more nucleons, and (2) pion production through the Δ resonance. The cross section due to quasi-free knockout can be reasonably well understood theoretically in a multiple scattering picture, which uses measured NN amplitudes as input. Calculations of this sort were carried out in reference [10] using scalar NN amplitudes parameterized as Gaussians. The author has extended this picture to include spin dependent NN amplitudes. This allows calculation of all the spin observables, Ay, DLL, DSS, DNN, DLS, and DSL, as well as the cross section dsigma/dOmegadp due to quasi-free knockout of one or more particles. The cross section and polarization Ay have been measured at the LAMPF High Resolution Spectrometer at T/sub L/ = 800 MeV on 12 C. The theoretical results agree well with the data in the quasi-free region. The results for the remaining spin observables provide predictions for experiments which can be performed at LAMPF. By comparing the calculations with the data, it may be possible to separate the contribution due to a quasi-free knockout, and see a signature of quasi-free Δ production in the spin observables

Spin-polarized spin excitation spectroscopy

International Nuclear Information System (INIS)

Loth, Sebastian; Lutz, Christopher P; Heinrich, Andreas J

2010-01-01

We report on the spin dependence of elastic and inelastic electron tunneling through transition metal atoms. Mn, Fe and Cu atoms were deposited onto a monolayer of Cu 2 N on Cu(100) and individually addressed with the probe tip of a scanning tunneling microscope. Electrons tunneling between the tip and the substrate exchange energy and spin angular momentum with the surface-bound magnetic atoms. The conservation of energy during the tunneling process results in a distinct onset threshold voltage above which the tunneling electrons create spin excitations in the Mn and Fe atoms. Here we show that the additional conservation of spin angular momentum leads to different cross-sections for spin excitations depending on the relative alignment of the surface spin and the spin of the tunneling electron. For this purpose, we developed a technique for measuring the same local spin with a spin-polarized and a non-spin-polarized tip by exchanging the last apex atom of the probe tip between different transition metal atoms. We derive a quantitative model describing the observed excitation cross-sections on the basis of an exchange scattering process.

In-medium effects around the Fermi energy

Directory of Open Access Journals (Sweden)

Lopez O.

2015-01-01

Full Text Available We study nuclear stopping in central collisions for heavy-ion induced reactions in the Fermi energy domain (15-100 AMeV. Using the large dataset provided by the 4π array INDRA, we determine that stopping can be directly related to the transport properties in the nuclear medium. By looking specifically at protons, we present a comprehensive body of experimental results concerning the mean free path, the nucleon-nucleon cross-section and in-medium effects in nuclear matter.

Development of a medium energy polarized neutron facility

International Nuclear Information System (INIS)

Burzynski, S.; Gysin, C.; Henneck, R.; Jourdan, J.; Kohler, D.; Pickar, M.A.; Plattner, G.R.; Sick, I.; Berdoz, A.; Foroughi, F.; Nussbaum, Ch.; Stammbach, Th.

1984-01-01

By the end of 1983 the major construction work for the new polarized neutron source was completed. The source will provide an essentially monoenergetic beam of both polarized and unpolarized neutrons in the energy range from 20 MeV to 70 MeV. Intensities are expected to be approx. 2 x 10 5 neutrons/s.cm 2 per μA of incident proton beam. The polarization is expected to be approx. 0.2 and can be chosen to be either longitudinal or transverse. Protons from the Philips injector cyclotron are focussed onto a liquid deuterium target and produce neutrons via the 2 H(p,n)2p reaction at 0 0 . This process provides essentially monoenergetic neutrons of almost the same energy as the incoming protons. The zero production angle implies that the neutron polarization comes from the polarization of the proton beam only. This allows an easy and fast change of the neutron spin direction by selecting proton spin states in the polarized ion source (atomic beam type). (Auth.)

Multichannel spin polarimeter for energy- and angle-dispersive photoemission measurements

International Nuclear Information System (INIS)

Kolbe, Michaela

2011-01-01

Spin polarization measurements of free electrons remain challenging since their first realization by Mott. The relevant quantity of a spin polarimeter is its figure of merit, FoM=S 2 I/I 0 , with the asymmetry function S and the ratio between scattered and primary intensity I/I 0 . State-of-the-art devices are based on single-channel scattering (spin-orbit or exchange interaction) which is characterized by FoM ≅10 -4 . On the other hand, modern hemispherical analyzers feature an efficient multichannel detection of spin-integral intensity with more than 10 4 data points simultaneously. In comparison between spin-resolved and spin-integral electron spectroscopy we are thus faced with a difference in counting efficiency by 8 orders of magnitude. The present work concentrates on the development and investigation of a novel technique for increasing the efficiency in spin-resolved electron spectroscopy by multichannel detection. The spin detector was integrated in a μ-metal shielded UHV-chamber and mounted behind a conventional hemispherical analyzer. The electrostatic lens system's geometry was determined by electron-optical simulations. The basic concept is the k parallel -conserving elastic scattering of the (0,0)-beam on a W(100) scattering crystal under 45 impact angle. It could be demonstrated that app. 960 data points (15 energy and 64 angular points) could be displayed simultaneously on a delayline detector in an energy interval of ≅3 eV. This leads to a two-dimensional figure of merit of FoM 2D =1.7. Compared to conventional spin detectors, the new type is thus characterized by a gain in efficiency of 4 orders of magnitude. The operational reliability of the new spin polarimeter could be proven by measurements with a Fe/MgO(100) and O p(1 x 1)/Fe(100)-sample, where results from the literature were reproduced with strongly decreased measuring time. Due to the high intensity it becomes possible, to investigate strongly reactive samples in a short time. This

EFFECTS OF SPIN ON HIGH-ENERGY RADIATION FROM ACCRETING BLACK HOLES

Energy Technology Data Exchange (ETDEWEB)

O’ Riordan, Michael; Pe’er, Asaf [Physics Department, University College Cork, Cork (Ireland); McKinney, Jonathan C., E-mail: michael_oriordan@umail.ucc.ie [Department of Physics and Joint Space-Science Institute, University of Maryland, College Park, MD 20742 (United States)

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.

Maximal Rashba-like spin splitting via kinetic-energy-coupled inversion-symmetry breaking

Science.gov (United States)

Sunko, Veronika; Rosner, H.; Kushwaha, P.; Khim, S.; Mazzola, F.; Bawden, L.; Clark, O. J.; Riley, J. M.; Kasinathan, D.; Haverkort, M. W.; Kim, T. K.; Hoesch, M.; Fujii, J.; Vobornik, I.; MacKenzie, A. P.; King, P. D. C.

2017-09-01

Engineering and enhancing the breaking of inversion symmetry in solids—that is, allowing electrons to differentiate between ‘up’ and ‘down’—is a key goal in condensed-matter physics and materials science because it can be used to stabilize states that are of fundamental interest and also have potential practical applications. Examples include improved ferroelectrics for memory devices and materials that host Majorana zero modes for quantum computing. Although inversion symmetry is naturally broken in several crystalline environments, such as at surfaces and interfaces, maximizing the influence of this effect on the electronic states of interest remains a challenge. Here we present a mechanism for realizing a much larger coupling of inversion-symmetry breaking to itinerant surface electrons than is typically achieved. The key element is a pronounced asymmetry of surface hopping energies—that is, a kinetic-energy-coupled inversion-symmetry breaking, the energy scale of which is a substantial fraction of the bandwidth. Using spin- and angle-resolved photoemission spectroscopy, we demonstrate that such a strong inversion-symmetry breaking, when combined with spin-orbit interactions, can mediate Rashba-like spin splittings that are much larger than would typically be expected. The energy scale of the inversion-symmetry breaking that we achieve is so large that the spin splitting in the CoO2- and RhO2-derived surface states of delafossite oxides becomes controlled by the full atomic spin-orbit coupling of the 3d and 4d transition metals, resulting in some of the largest known Rashba-like spin splittings. The core structural building blocks that facilitate the bandwidth-scaled inversion-symmetry breaking are common to numerous materials. Our findings therefore provide opportunities for creating spin-textured states and suggest routes to interfacial control of inversion-symmetry breaking in designer heterostructures of oxides and other material classes.

Micromagnetism in (001) magnetite by spin-polarized low-energy electron microscopy

International Nuclear Information System (INIS)

Figuera, Juan de la; Vergara, Lucía; N'Diaye, Alpha T.; Quesada, Adrian; Schmid, Andreas K.

2013-01-01

Spin-polarized low-energy electron microscopy was used to image a magnetite crystal with (001) surface orientation. Sets of spin-dependent images of magnetic domain patterns observed in this surface were used to map the direction of the magnetization vector with high spatial and angular resolution. We find that domains are magnetized along the surface directions, and domain wall structures include 90° and 180° walls. A type of unusually curved domain walls are interpreted as Néel-capped surface terminations of 180° Bloch walls. - Highlights: ► The (001) surface of magnetite is imaged by spin-polarized low-energy electron microscopy. ► The magnetic domain microstructure is resolved. ► Magnetic easy axes in this surface are found to be along directions. ► Magnetic domain wall structures include wide Néel-caps

Micromagnetism in (001) magnetite by spin-polarized low-energy electron microscopy

Energy Technology Data Exchange (ETDEWEB)

Figuera, Juan de la, E-mail: juan.delafiguera@iqfr.csic.es [Instituto de Química-Física “Rocasolano”, CSIC, Madrid 28006 (Spain); Vergara, Lucía [Instituto de Química-Física “Rocasolano”, CSIC, Madrid 28006 (Spain); N' Diaye, Alpha T. [Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Quesada, Adrian [Instituto de Cerámica y Vidrio, CSIC, Calle Kelsen 5, 28049, Madrid (Spain); Schmid, Andreas K. [Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States)

2013-07-15

Spin-polarized low-energy electron microscopy was used to image a magnetite crystal with (001) surface orientation. Sets of spin-dependent images of magnetic domain patterns observed in this surface were used to map the direction of the magnetization vector with high spatial and angular resolution. We find that domains are magnetized along the surface <110> directions, and domain wall structures include 90° and 180° walls. A type of unusually curved domain walls are interpreted as Néel-capped surface terminations of 180° Bloch walls. - Highlights: ► The (001) surface of magnetite is imaged by spin-polarized low-energy electron microscopy. ► The magnetic domain microstructure is resolved. ► Magnetic easy axes in this surface are found to be along <110> directions. ► Magnetic domain wall structures include wide Néel-caps.

Free-energy analysis of spin models on hyperbolic lattice geometries.

Science.gov (United States)

Serina, Marcel; Genzor, Jozef; Lee, Yoju; Gendiar, Andrej

2016-04-01

We investigate relations between spatial properties of the free energy and the radius of Gaussian curvature of the underlying curved lattice geometries. For this purpose we derive recurrence relations for the analysis of the free energy normalized per lattice site of various multistate spin models in the thermal equilibrium on distinct non-Euclidean surface lattices of the infinite sizes. Whereas the free energy is calculated numerically by means of the corner transfer matrix renormalization group algorithm, the radius of curvature has an analytic expression. Two tasks are considered in this work. First, we search for such a lattice geometry, which minimizes the free energy per site. We conjecture that the only Euclidean flat geometry results in the minimal free energy per site regardless of the spin model. Second, the relations among the free energy, the radius of curvature, and the phase transition temperatures are analyzed. We found out that both the free energy and the phase transition temperature inherit the structure of the lattice geometry and asymptotically approach the profile of the Gaussian radius of curvature. This achievement opens new perspectives in the AdS-CFT correspondence theories.

Time-domain electromagnetic energy in a frequency-dispersive left-handed medium

International Nuclear Information System (INIS)

Cui Tiejun; Kong Jinau

2004-01-01

From Maxwell's equations and the Poynting theorem, the time-domain electric and magnetic energy densities are generally defined in the frequency-dispersive media based on the conservation of energy. As a consequence, a general definition of electric and magnetic energy is proposed. Comparing with existing formulations of electric and magnetic energy in frequency-dispersive media, the new definition is more reasonable and is valid in any case. Using the new definition and staring from the equation of motion, we have shown rigorously that the total energy density and the individual electric and magnetic energy densities are always positive in a realistic artificial left-handed medium (LHM) [R. A. Shelby, D. R. Smith, and S. Schultz, Science 292, 77 (2001)], which obeys actually the Lorentz medium model, although such a LHM has negative permittivity and negative permeability simultaneously in a certain frequency range. We have also shown that the conservation of energy is not violated in LHM. The earlier conclusions can be easily extended to the Drude medium model and the cold plasma medium model. Through an exact analysis of a one-dimensional transient current source radiating in LHM, numerical results are given to demonstrate that the work done by source, the power flowing outwards a surface, and the electric and magnetic energy stored in a volume are all positive in the time domain

Quantum mechanical equations of particle and spin motion in polarised medium

International Nuclear Information System (INIS)

Silenko, A.Ya.

2003-01-01

The quantum mechanical equations for the particles and spin motion in the media with polarized electrons by presence of the external fields are determined. The motion of the electrons and their spin are influenced by the exchange interaction whereas the motion of the positrons is the annihilation one. The second order summands by spin are accounted for the particles with the S≥1 spin. The obtained equations may applied for describing the particles and spin motion both in the magnetic and nonmagnetic media [ru

Thermodynamical inequivalence of quantum stress-energy and spin tensors

International Nuclear Information System (INIS)

Becattini, F.; Tinti, L.

2011-01-01

It is shown that different couples of stress-energy and spin tensors of quantum-relativistic fields, which would be otherwise equivalent, are in fact inequivalent if the second law of thermodynamics is taken into account. The proof of the inequivalence is based on the analysis of a macroscopic system at full thermodynamical equilibrium with a macroscopic total angular momentum and a specific instance is given for the free Dirac field, for which we show that the canonical and Belinfante stress-energy tensors are not equivalent. For this particular case, we show that the difference between the predicted angular momentum densities for a rotating system at full thermodynamical equilibrium is a quantum effect, persisting in the nonrelativistic limit, corresponding to a polarization of particles of the order of (ℎ/2π)ω/KT (ω being the angular velocity) and could in principle be measured experimentally. This result implies that specific stress-energy and spin tensors are physically meaningful even in the absence of gravitational coupling and raises the issue of finding the thermodynamically right (or the right class of) tensors. We argue that the maximization of the thermodynamic potential theoretically allows us to discriminate between two different couples, yet for the present we are unable to provide a theoretical method to single out the best couple of tensors in a given quantum field theory. The existence of a nonvanishing spin tensor would have major consequences in hydrodynamics, gravity and cosmology.

The origin of nuclear spin and its effect durning intermediate energy heavy ion collisions

International Nuclear Information System (INIS)

Zhang Guoqiang; Cao Xiguang; Fu Yao; Ma Yugang; Cai Xiangzhou; Wang Hongwei; Fang Deqing; Tian Wendong; Chen Jingen; Guo Wei; Liu Guihua

2010-01-01

We use the heavy-ion phase-space exploration (HIPSE) model to discuss the origin of the nuclear spin and its effect in Intermediate energy nuclear reaction. It is found that the spin of projectile depends on the impact parameter of the reaction system heavily, while on the violence lightly by contrast. Some interesting multifragmentation phenomena related to the spin are shown, especially those of phase transition. At the same time, the role of excited energy for multifragmentation is also invested. We find the later plays a more robust role durning the nuclear disintegration. (authors)

Relativistic energy loss in a dispersive medium

DEFF Research Database (Denmark)

Houlrik, Jens Madsen

2002-01-01

The electron energy loss in a dispersive medium is obtained using macroscopic electrodynamics taking advantage of a static frame of reference. Relativistic corrections are described in terms of a dispersive Lorentz factor obtained by replacing the vacuum velocity c by the characteristic phase...... velocity c/n, where n is the complex index of refraction. The angle-resolved energy-loss spectrum of a Drude conductor is analyzed in detail and it is shown that the low-energy peak due to Ohmic losses is enhanced compared to the classical approximation....

Violation of a Bell-like inequality for spin-energy entanglement in neutron polarimetry

International Nuclear Information System (INIS)

Sponar, S.; Klepp, J.; Zeiner, C.; Badurek, G.; Hasegawa, Y.

2010-01-01

Violation of a Bell-like inequality for a spin-energy entangled neutron state has been demonstrated in a polarimetric experiment. The proposed inequality, in Clauser-Horne-Shimony-Holt (CHSH) formalism, relies on correlations between the spin and energy degree of freedom in a single-neutron system. The correlation function S CHSH is determined to be 2.333±0.002≤/2, which violates the Bell-like CHSH inequality by more than 166 standard deviations.

Non-eikonal corrections for the scattering of spin-one particles

Energy Technology Data Exchange (ETDEWEB)

Gaber, M.W.; Wilkin, C. [Department of Physics and Astronomy, University College London, WC1E 6BT, London (United Kingdom); Al-Khalili, J.S. [Department of Physics, University of Surrey, GU2 7XH, Guildford, Surrey (United Kingdom)

2004-08-01

The Wallace Fourier-Bessel expansion of the scattering amplitude is generalised to the case of the scattering of a spin-one particle from a potential with a single tensor coupling as well as central and spin-orbit terms. A generating function for the eikonal-phase (quantum) corrections is evaluated in closed form. For medium-energy deuteron-nucleus scattering, the first-order correction is dominant and is shown to be significant in the interpretation of analysing power measurements. This conclusion is supported by a numerical comparison of the eikonal observables, evaluated with and without corrections, with those obtained from a numerical resolution of the Schroedinger equation for d-{sup 58}Ni scattering at incident deuteron energies of 400 and 700 MeV. (orig.)

Spin-dependent parton distributions in the nucleon

Energy Technology Data Exchange (ETDEWEB)

Cloet, I.C. [Special Research Centre for the Subatomic Structure of Matter and Department of Physics and Mathematical Physics, University of Adelaide, SA 5005 (Australia); Bentz, W. [Department of Physics, School of Science, Tokai University Hiratsuka-shi, Kanagawa 259-1292 (Japan); Thomas, A.W. [Jefferson Lab, 12000 Jefferson Avenue, Newport News, VA 23606 (United States)

2005-04-15

Spin-dependent quark light-cone momentum distributions are calculated for a nucleon in the nuclear medium. We utilize a modified NJL model where the nucleon is described as a composite quark-diquark state. Scalar and vector mean fields are incorporated in the nuclear medium and these fields couple to the confined quarks in the nucleon. The effect of these fields on the spin-dependent distributions and consequently the axial charges is investigated. Our results for the 'spin-dependent EMC effect' are also discussed.

Medium Access Control in Energy Harvesting - Wireless Sensor Networks

DEFF Research Database (Denmark)

Fafoutis, Xenofon

Focusing on Wireless Sensor Networks (WSN) that are powered by energy harvesting, this dissertation focuses on energy-efficient communication links between senders and receivers that are alternating between active and sleeping states of operation. In particular, the focus lies on Medium Access...

Compound nucleus effects in spin-spin cross sections

International Nuclear Information System (INIS)

Thompson, W.J.

1976-01-01

By comparison with recent data, it is shown that spin-spin cross sections for low-energy neutrons may be dominated by a simple compound-elastic level-density effect, independent of spin-spin terms in the nucleon-nucleus optical-model potential. (Auth.)

Medium energy probes and nuclear structure

International Nuclear Information System (INIS)

Ginocchio, J.N.

1984-01-01

In this paper we explore two topics. The first topic is the marriage of medium energy reaction theory with the interacting boson model of nuclei in such a way that the multiple scattering is summed to all orders. The second topic is an exactly solvable potential model which gives realistic shell model eigenfunctions which can be used to calculate static and transition nuclear densities. (orig./HSI)

Low energy recycling of ionic liquids via freeze crystallization during cellulose spinning

DEFF Research Database (Denmark)

Liu, Yanrong; Meyer, Anne S.; Nie, Yi

2018-01-01

recycling method. EmimAc + 12.5 wt% H2O and EmimDep + 4 wt% H2O were selected for a quantitative mass and energy analysis of the cellulose spinning and IL recycling process (the maximal initial H2O levels in the ILs + H2O mixtures for cellulose dissolution were determined experimentally). The energy......Dep recycling. We also show that compared to a classical Lyocell fiber production method using N-methylmorpholine-N-oxide (NMMO) as solvent, use of ILs is energy saving in itself. Hence, significantly less H2O is required in the cellulose spinning process with ILs than with NMMO, and in turn less H2O has...

Spin conversion induced by spin-orbit interaction in positronium collisions

International Nuclear Information System (INIS)

Saito, H; Nakayama, T; Hyodo, T

2009-01-01

The positronium spin conversion reaction induced by spin-orbit interaction is investigated. We obtain the reaction rates during positronium-Xe and positronium-Kr collisions by using the Zeeman mixing of positronium states. At thermal energies corresponding to room temperature, the reaction rate for spin conversion due to spin-orbit interaction is found to be almost twice that for the positronium pick-off reaction. We also study the energy dependence of the reaction rate. The mean energy of positronium is controlled by changing the gas temperature and using positronium in thermal equilibrium. We found that the reaction rate increases with the collision energy.

Origin of the finite nuclear spin and its effect in intermediate energy heavy ion collisions

International Nuclear Information System (INIS)

Zhang Guoqiang; Cao Xiguang; Fu Yao

2012-01-01

The heavy-ion phase-space exploration (HIPSE) model is used to discuss the origin of the nuclear spin in intermediate energy heavy-ion collision (HIC). The spin of maximal projectile-like fragment is found to depend strongly on impact parameter of a reaction system,while it relates weakly to the collision violence. Some interesting multi-fragmentation phenomena related to the spin are shown. We also found that the excitation energy in the de-excitation stage plays a robust role at the de-excitation stage in HIC. (authors)

Spin-flip inelastic scattering in electron energy loss spectroscopy of a ferromagnetic metal

International Nuclear Information System (INIS)

Yin, S.; Tosatti, E.

1981-08-01

We calculate the spin polarization occuring during electron inelastic scattering from electron-hole pairs in a model ferromagnetic metal. The polarization is found to have contributions from unequal spin flip as well as non-flip energy loss rates. Our results indicate an asymmetry of the order of a few percent with parameters roughly modeling Fsub(e). The possibilities of comparison with experiments in the presence of simultaneous spin-polarizing elastic scattering are discussed. (author)

Spin- and energy-dependent tunneling through a single molecule with intramolecular spatial resolution.

Science.gov (United States)

Brede, Jens; Atodiresei, Nicolae; Kuck, Stefan; Lazić, Predrag; Caciuc, Vasile; Morikawa, Yoshitada; Hoffmann, Germar; Blügel, Stefan; Wiesendanger, Roland

2010-07-23

We investigate the spin- and energy-dependent tunneling through a single organic molecule (CoPc) adsorbed on a ferromagnetic Fe thin film, spatially resolved by low-temperature spin-polarized scanning tunneling microscopy. Interestingly, the metal ion as well as the organic ligand show a significant spin dependence of tunneling current flow. State-of-the-art ab initio calculations including also van der Waals interactions reveal a strong hybridization of molecular orbitals and substrate 3d states. The molecule is anionic due to a transfer of one electron, resulting in a nonmagnetic (S=0) state. Nevertheless, tunneling through the molecule exhibits a pronounced spin dependence due to spin-split molecule-surface hybrid states.

PROCEEDINGS OF RIKEN BNL RESEARCH CENTER WORKSHOP CIRCUM-PAN-PACIFIC RIKEN SYMPOSIUM ON HIGH ENERGY SPIN PHYSICS, VOLUME 25

Energy Technology Data Exchange (ETDEWEB)

KUMANO,S.; SHIBATA,T.A.; YAZAKI,K.

2000-06-28

The Circum-Pan-Pacific Riken Symposium on High Energy Spin Physics was held at Oukouchi Memorial Hall in Riken from November 3 through 6, 1999. It was held as a joint meeting of the 2nd Circum-Pan-Pacific Symposium on High Energy Spin Physics and the 3rd of the series of Riken Symposia related to the RHIC-SPIN. The 1st Circum-Pan-Pacific Symposium on High Energy Spin Physics was held at Kobe in 1996 and the RHIC-SPIN Riken Symposia had been held every two years since 1995. As Prof. Ozaki mentioned in his talk at the beginning of this meeting, the RHIC was ready for the first beam, physics experiments scheduled in 2000, and the RHIC-SPIN would start in 2001. It was therefore considered to be very timely for the researchers in the field of high energy spin physics to get together, clarifying the present status of the field and discussing interesting and important topics as well as experimental subjects to be pursued. It is especially important for the success of the RHIC-SPIN project that the researchers in the neighboring countries surrounding the Pacific are actively involved in it. This is why the above two series were joined in this. symposium. The subjects discussed in the symposium include: Hard processes probing spin-structure functions, polarization mechanisms in high energy reactions, lattice studies of polarized structure functions, theoretical models for the nucleon and its spin structure, RHIC and RHIC-SPIN projects, results and future projects of existing experimental facilities. Totally 73 scientists participated in the symposium, 27 from abroad and 46 from Japan. it consisted of 13 main sessions, with 33 invited and contributed talks, and 4 discussion sessions covering recent experimental and theoretical developments and important topics in high energy spin physics and closely related fields.

Inelastic neutron scattering in the spin wave energy gap of the polydomain γ-Mn(12%Ge) alloy

International Nuclear Information System (INIS)

Jankowska-Kisielinska, J.; Mikke, K.

1999-01-01

The subject of the present experiment was the investigation of the inelastic neutron scattering (INS) for energy transfers lower than and close to the energy gap of the spin wave spectrum for long wavelengths. The aim was a search for the excitations at the magnetic Brillouin zone (MBZ) boundary in polydomain Mn(12%Ge) alloy. The present measurements were performed by a 3-axis spectrometer at Maria Reactor at IEA in Swierk. We observed the INS in the polydomain Mn(12%Ge) alloy for energies smaller than and close to the energy gap value of the spin wave spectrum at room temperature. The observed intensity can be treated as a sum of intensity of neutrons scattered on spin waves around magnetic Brillouin zone centre and that of neutrons scattered on fluctuations at the zone boundary. The intensity of both components for energies 2-6 MeV was found to be of the same order. For higher energies spin waves around magnetic zone centre dominate. (author)

Photon energy dependence of photo-induced inverse spin-Hall effect in Pt/GaAs and Pt/Ge

Energy Technology Data Exchange (ETDEWEB)

Isella, Giovanni, E-mail: giovanni.isella@polimi.it; Bottegoni, Federico; Ferrari, Alberto; Finazzi, Marco; Ciccacci, Franco [LNESS-Dipartimento di Fisica, Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133 Milano (Italy)

2015-06-08

We report the photon energy dependence of photo-induced inverse spin Hall effect (ISHE) in Pt/GaAs and Pt/Ge Schottky junctions. The experimental results are compared with a spin drift-diffusion model, which highlights the role played by the different spin lifetime in the two semiconductors, in determining the energy dependence of the ISHE signal detected in the Pt layer. The good qualitative agreement between experiments and modelling indicates that photo-induced ISHE can be used as a tool to characterize spin lifetime in semiconductors.

El strength function at high spin and excitation energy

International Nuclear Information System (INIS)

Barrette, J.

1983-04-01

Recently giant dipole resonance-like concentration of the dipole strength function in nuclei was observed at both high excitation energies and high spins. This observation raises the possibility of obtaining new information on the shape of rapidly rotating heated nuclei. Recent experimental results on this subject are reviewed

Energy spectrum, the spin polarization, and the optical selection rules of the Kronig-Penney superlattice model with spin-orbit coupling

Science.gov (United States)

Li, Rui

2018-02-01

The Kronig-Penney model, an exactly solvable one-dimensional model of crystal in solid physics, shows how the allowed and forbidden bands are formed in solids. In this paper, we study this model in the presence of both strong spin-orbit coupling and the Zeeman field. We analytically obtain four transcendental equations that represent an implicit relation between the energy and the Bloch wave vector. Solving these four transcendental equations, we obtain the spin-orbital bands exactly. In addition to the usual band gap opened at the boundary of the Brillouin zone, a much larger spin-orbital band gap is also opened at some special sites inside the Brillouin zone. The x component of the spin-polarization vector is an even function of the Bloch wave vector, while the z component of the spin-polarization vector is an odd function of the Bloch wave vector. At the band edges, the optical transition rates between adjacent bands are nonzero.

Equations of motion of test particles for solving the spin-dependent Boltzmann–Vlasov equation

Energy Technology Data Exchange (ETDEWEB)

Xia, Yin [Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800 (China); University of Chinese Academy of Science, Beijing 100049 (China); Xu, Jun, E-mail: xujun@sinap.ac.cn [Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800 (China); Li, Bao-An [Department of Physics and Astronomy, Texas A& M University-Commerce, Commerce, TX 75429-3011 (United States); Department of Applied Physics, Xi' an Jiao Tong University, Xi' an 710049 (China); Shen, Wen-Qing [Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800 (China)

2016-08-10

A consistent derivation of the equations of motion (EOMs) of test particles for solving the spin-dependent Boltzmann–Vlasov equation is presented. The resulting EOMs in phase space are similar to the canonical equations in Hamiltonian dynamics, and the EOM of spin is the same as that in the Heisenburg picture of quantum mechanics. Considering further the quantum nature of spin and choosing the direction of total angular momentum in heavy-ion reactions as a reference of measuring nucleon spin, the EOMs of spin-up and spin-down nucleons are given separately. The key elements affecting the spin dynamics in heavy-ion collisions are identified. The resulting EOMs provide a solid foundation for using the test-particle approach in studying spin dynamics in heavy-ion collisions at intermediate energies. Future comparisons of model simulations with experimental data will help to constrain the poorly known in-medium nucleon spin–orbit coupling relevant for understanding properties of rare isotopes and their astrophysical impacts.

Energy levels of a spin-orbit-coupled Bose-Einstein condensate in a double-well potential

Science.gov (United States)

Wang, Wen-Yuan; Cao, Hui; Zhu, Shi-Liang; Liu, Jie; Fu, Li-Bin

2015-02-01

We investigate the energy levels of a spin-orbit-coupled Bose-Einstein condensate in a double-well potential under the mean-field approximation. We find that the energy levels of the system can be significantly influenced by the atomic interactions. Without atomic interaction, four energy levels change linearly with the tunneling amplitude, the Raman coupling, and the spin-orbit coupling. However, whenever atomic interaction is considered, three more energy levels will appear, which have a nonlinear dependence on those parameters above. These three energy levels are multi-degenerate and related to the macro-symmetry of the system.

Medium-energy ion reflection from solids

CERN Document Server

Mashkova, ES

1985-01-01

``Medium-Energy Ion Reflection from Solids'' analyses the results of experimental, theoretical and computer investigations on the process of scattering of ions by solid surfaces. Surface scattering is a relatively young and rapidly developing branch of the physics of atomic collisions and the literature on this subject has rapidly grown.As the first monograph devoted specifically to surface scattering of ions, this book is directed at scientists involved in ion-solid interaction studies.

Multichannel spin polarimeter for energy- and angle-dispersive photoemission measurements; Vielkanal-Spinpolarimeter fuer energie- und winkeldispersive Photoemissionsmessungen

Energy Technology Data Exchange (ETDEWEB)

Kolbe, Michaela

2011-09-09

Spin polarization measurements of free electrons remain challenging since their first realization by Mott. The relevant quantity of a spin polarimeter is its figure of merit, FoM=S{sup 2}I/I{sub 0}, with the asymmetry function S and the ratio between scattered and primary intensity I/I{sub 0}. State-of-the-art devices are based on single-channel scattering (spin-orbit or exchange interaction) which is characterized by FoM {approx_equal}10{sup -4}. On the other hand, modern hemispherical analyzers feature an efficient multichannel detection of spin-integral intensity with more than 10{sup 4} data points simultaneously. In comparison between spin-resolved and spin-integral electron spectroscopy we are thus faced with a difference in counting efficiency by 8 orders of magnitude. The present work concentrates on the development and investigation of a novel technique for increasing the efficiency in spin-resolved electron spectroscopy by multichannel detection. The spin detector was integrated in a {mu}-metal shielded UHV-chamber and mounted behind a conventional hemispherical analyzer. The electrostatic lens system's geometry was determined by electron-optical simulations. The basic concept is the k {sub parallel} -conserving elastic scattering of the (0,0)-beam on a W(100) scattering crystal under 45 impact angle. It could be demonstrated that app. 960 data points (15 energy and 64 angular points) could be displayed simultaneously on a delayline detector in an energy interval of {approx_equal}3 eV. This leads to a two-dimensional figure of merit of FoM{sub 2D}=1.7. Compared to conventional spin detectors, the new type is thus characterized by a gain in efficiency of 4 orders of magnitude. The operational reliability of the new spin polarimeter could be proven by measurements with a Fe/MgO(100) and O p(1 x 1)/Fe(100)-sample, where results from the literature were reproduced with strongly decreased measuring time. Due to the high intensity it becomes possible, to

Spin-orbit beams for optical chirality measurement

Science.gov (United States)

Samlan, C. T.; Suna, Rashmi Ranjan; Naik, Dinesh N.; Viswanathan, Nirmal K.

2018-01-01

Accurate measurement of chirality is essential for the advancement of natural and pharmaceutical sciences. We report here a method to measure chirality using non-separable states of light with geometric phase-gradient in the circular polarization basis, which we refer to as spin-orbit beams. A modified polarization Sagnac interferometer is used to generate spin-orbit beams wherein the spin and orbital angular momentum of the input Gaussian beam are coupled. The out-of-phase interference between counter-propagating Gaussian beams with orthogonal spin states and lateral-shear or/and linear-phase difference between them results in spin-orbit beams with linear and azimuthal phase gradient. The spin-orbit beams interact efficiently with the chiral medium, inducing a measurable change in the center-of-mass of the beam, using the polarization rotation angle and hence the chirality of the medium are accurately calculated. Tunable dynamic range of measurement and flexibility to introduce large values of orbital angular momentum for the spin-orbit beam, to improve the measurement sensitivity, highlight the techniques' versatility.

Energy dissipation during an explosion in a porous elasto-plastic medium

Energy Technology Data Exchange (ETDEWEB)

Lovetskii, E.E.; Maslennikov, A.M.; Fetisov, V.S.

1979-01-01

A study is made of the redistribution of energy from camouflage blasting in a saturated porous medium. The study is undertaken with the aid of a numerical solution to a system of hydrodynamic equations, that account for shear strength of the substance under investigation. A study is made of the energy characteristics of explosion, their dynamic development, the influence of strength parameters of the medium, and porosity on these characteristics. A mechanism that is associated with the impact compression of matter is identified as the basic mechanism of energy dissipation for dry porous media. Water saturation of pores brings the energy characteristics of the explosion close to the explosion in a monolith. 12 references, 5 figures, 1 table.

Single reference Coupled Cluster treatment of nearly degenerate problems: Cohesive energy of antiferromagnetic lattices of spin 1 centers

International Nuclear Information System (INIS)

Malrieu, Jean-Paul

2012-01-01

Lattices of antiferromagnetically coupled spins, ruled by Heisenberg Hamiltonians, are intrinsically highly degenerate systems. The present work tries to estimate the ground state energy of regular bipartite spin lattices of S = 1 sites from a single reference Coupled Cluster expansion starting from a Néel function, taken as reference. The simultaneous changes of spin momentum on adjacent sites play the role of the double excitations in molecular electronic problems. Propagation of the spin changes plays the same role as the triple excitations. The treatment takes care of the deviation of multiple excitation energies from additivity. Specific difficulties appear for 1D chains, which are not due to a near degeneracy between the reference and the vectors which directly interact with it but to the complexity of the processes which lead to the low energy configurations where a consistent reversed-Néel domain is created inside the Néel starting spin wave. Despite these difficulties a reasonable value of the cohesive energy is obtained.

Single reference Coupled Cluster treatment of nearly degenerate problems: Cohesive energy of antiferromagnetic lattices of spin 1 centers

Science.gov (United States)

Malrieu, Jean-Paul

2012-06-01

Lattices of antiferromagnetically coupled spins, ruled by Heisenberg Hamiltonians, are intrinsically highly degenerate systems. The present work tries to estimate the ground state energy of regular bipartite spin lattices of S = 1 sites from a single reference Coupled Cluster expansion starting from a Néel function, taken as reference. The simultaneous changes of spin momentum on adjacent sites play the role of the double excitations in molecular electronic problems. Propagation of the spin changes plays the same role as the triple excitations. The treatment takes care of the deviation of multiple excitation energies from additivity. Specific difficulties appear for 1D chains, which are not due to a near degeneracy between the reference and the vectors which directly interact with it but to the complexity of the processes which lead to the low energy configurations where a consistent reversed-Néel domain is created inside the Néel starting spin wave. Despite these difficulties a reasonable value of the cohesive energy is obtained.

Medium-Energy Nuclear Data Library (MENDLIB): Phase 1

International Nuclear Information System (INIS)

Siciliano, E.R.; Arthur, E.D.

1987-10-01

This document describes an initial step towards the formation of a computerized on-line data library, which would contain published medium-energy experimental data, and which would serve the basic and applied needs of the medium-energy nuclear physics community. The data emphasized in this project will be from measured charged-particle and meson induced nuclear scattering and reactions; an area for which no such data base presently exists. Access to the data will be through a menu-driven program in a user-friendly environment. The project is divided into three phases: Phase 1 involves compilation of Clinton P. Anderson Meson Physics Facility (LAMPF) data from nucleon and pion induced reactions, Phase 2 includes nucleon and pion data from other medium-energy facilities, and Phase 3 includes electron, light-ion, and possibly kaon and anti-nucleon data. The initial goals, the manner in which they would be pursued, and the resources needed to implement Phase 1 (the pilot phase) are discussed in detail. Possible expansion of Phase 1 to attain the envisioned goals of Phase 2 and 3 are briefly outlined. During all stages of the project, input from the community will be sought via the various facility user groups and the American Physical Society Division of Nuclear Physics. It is proposed that the Applied Nuclear Science Group (T-2) of the Los Alamos National Laboratory oversees the development and implementation of this project, and the LAMPF VAX computers be used as the host computers for on-line access

High-energy hadron spin-flip amplitude at small momentum transfer and new AN data from RHIC

International Nuclear Information System (INIS)

Cudell, J.-R.; Selyugin, O.V.; Predazzi, E.

2004-01-01

In the case of elastic high-energy hadron-hadron scattering, the impact of the large-distance contributions on the behaviour of the slopes of the spin-non-flip and of the spin-flip amplitudes is analysed. It is shown that the long tail of the hadronic potential in impact parameter space leads to a value of the slope of the reduced spin-flip amplitude larger than that of the spin-non-flip amplitude. This effect is taken into account in the calculation of the analysing power in proton-nucleus reactions at high energies. It is shown that the preliminary measurement of A N for p 12 C obtained by the E950 Collaboration indeed favours a spin-flip amplitude with a large slope. Predictions for A N at p L =250/ GeV/c are given. (orig.)

Scattering amplitude and shift in self-energy in medium

International Nuclear Information System (INIS)

Mallik, S.

2002-01-01

Two simple proofs are presented for the first order virial expansion of the self-energy of a particle moving through a medium, characterised by temperature and/or chemical potential(s). One is based on the virial expansion of the self-energy operator itself, while the other is based on the analysis of its Feynman diagrams in configuration space. (orig.)

Technical Support Document: 50% Energy Savings Design Technology Packages for Medium Office Buildings

Energy Technology Data Exchange (ETDEWEB)

Thornton, Brian A.; Wang, Weimin; Lane, Michael D.; Rosenberg, Michael I.; Liu, Bing

2009-09-01

This Technical Support Document (TSD) describes the process and methodology for development of the Advanced Energy Design Guide for Medium Offices (AEDG-MO or the Guide), a design guidance document which intends to provide recommendations for achieving 50% energy savings in medium office buildings that just meet the requirements of ANSI/ASHRAE/IESNA Standard 90.1-2004, Energy Standard for Buildings Except Low-Rise Residential Buildings.

FERMILAB: High energy spin effects

Energy Technology Data Exchange (ETDEWEB)

Anon.

1991-03-15

While many physicists would agree that it is important to study interactions of different isospin states (for example comparing proton and neutron data), many of them also accept as normal data averaged or integrated over ordinary spin. However an ongoing programme at Brookhaven studying elastic scattering (where the incoming particles 'bounce' off each other) produced marked spin effects which are not well understood. Our understanding of particle interactions should not be influenced by which observables are easy to measure and which aren't, and until a clear understanding of spin effects emerges, it is important to continue and extend these studies.

Free neutron-proton analyzing power at medium energies

International Nuclear Information System (INIS)

Newsom, C.R.

1980-01-01

In recent years, increasing efforts have been made to measure the nucleon-nucleon polarization parameters. To date, no free neutron-proton spin correlated parameters have been published in the energy range 500 to 800 MeV. Existing analyzing power data is of low precision and in most cases was obtained by quasi-free proton scattering. As a first step in determining the neutron-proton scattering matrix, the free neutron-proton analyzing power has been measured at the Los Alamos Physics Facility as a function of energy and angle. The experiment was performed by scattering a neutron beam from a polarized proton target. The neutron beam was generated by scattering 800 MeV protons from a Beryllium target and using the neutrons produced at 0 degrees. The incident energy ranged from 300 MeV to 800 MeV. The energy spread of the neutron beam made it possible to measure the analyzing power at different energies simultaneously. Angular distributions were taken from 60 to 170 degrees in the center of mass system (c.m.)

Significance of high energy spin effects in constituent pictures

International Nuclear Information System (INIS)

Chen, C.K.

1977-01-01

The spin information about high energy hadronic reactions is important for further understanding of the nature and the behavior of hadronic constituents. The usefulness of the information is discussed in the cases of dilepton production from hadronic collisions, large P/sub T/ inclusive and elastic scatterings, and small angle elastic scattering and quantum number exchanged reactions

SLAC workshop on high energy electroproduction and spin physics

International Nuclear Information System (INIS)

1992-01-01

These Proceedings contain copies of the transparencies presented at the Workshop on High Energy Electroproduction and Spin Physics held at SLAC on February 5--8, 1992. The purpose of this Workshop was to bring people together to discuss the possibilities for new experiments using the SLAC high intensity electron and photon beams and the facilities of End Station A

Spin Filters as High-Performance Spin Polarimeters

International Nuclear Information System (INIS)

Rougemaille, N.; Lampel, G.; Peretti, J.; Drouhin, H.-J.; Lassailly, Y.; Filipe, A.; Wirth, T.; Schuhl, A.

2003-01-01

A spin-dependent transport experiment in which hot electrons pass through a ferromagnetic metal / semiconductor Schottky diode has been performed. A spin-polarized free-electron beam, emitted in vacuum from a GaAs photocathode, is injected into the thin metal layer with an energy between 5 and 1000 eV above to the Fermi level. The transmitted current collected in the semiconductor substrate increases with injection energy because of secondary - electron multiplication. The spin-dependent part of the transmitted current is first constant up to about 100 eV and then increases by 4 orders of magnitude. As an immediate application, the solid-state hybrid structure studied here leads to a very efficient and compact device for spin polarization detection

Electron spin polarization in high-energy storage rings

International Nuclear Information System (INIS)

Mane, S.R.

1987-01-01

In a high energy storage ring, a single photon emission has relatively little effect on the orbital motion, but it can produce a relatively large change in the electron spin state. Hence the unperturbed orbital motion can be satisfactorily described using classical mechanics, but the spin must be treated quantum mechanically. The electron motion is therefore treated semi-classically in this thesis. It is explained how to diagonalize the unperturbed Hamiltonian to the leading order in Planck's constant. The effects of perturbations are then included, and the relevant time-scales and ensemble averages are elucidated. The Derbenev-Kondratenko formula for the equilibrium degree of polarization is rederived. Mathematical details of the rederivation are given. Since the original authors used a different formalism, a proof is offered of the equivalence between their method and the one used in this thesis. An algorithm is also presented to evaluate the equilibrium polarization. It has a number of new features, which enable the polarization to be calculated to a higher degree of approximation than has hitherto been possible. This facilitates the calculation of so-called spin resonances, which are points at which the polarization almost vanishes. A computer program has been written to implement the above algorithm, in the approximation of linear orbital dynamics, and sample results are presented

Studies in medium energy physics

International Nuclear Information System (INIS)

Green, A.; Hoffmann, G.W.; McDonough, J.; Purcell, M.J.; Ray, R.L.; Read, D.E.; Worn, S.D.

1991-12-01

This document constitutes the (1991--1992) technical progress report and continuation proposal for the ongoing medium energy nuclear physics research program supported by the US Department of Energy through special Research Grant DE-FG05-88ER40444. The experiments discussed are conducted at the Los Alamos National Laboratory's (LANL) Clinton P. Anderson Meson Physics Facility (LAMPF) and the Alternating Gradient Synchrotron (AGS) facility of the Brookhaven National Laboratory (BNL). The overall motivation for the work discussed in this document is driven by three main objectives: (1) provide hadron-nucleon and hadron-nucleus scattering data which serve to facilitate the study of effective two-body interactions, test (and possibly determine) nuclear structure, and help study reaction mechanisms and dynamics; (2) provide unique, first-of-a-kind ''exploratory'' hadron-nucleus scattering data in the hope that such data will lead to discovery of new phenomena and new physics; and (3) perform precision tests of fundamental interactions, such as rare decay searches, whose observation would imply fundamental new physics

Spin flip inelastic scattering in electron energy loss spectroscopy of a ferromagnetic metal

International Nuclear Information System (INIS)

Bocchetta, C.J.; Tosatti, E.; Yin, S.

1986-11-01

A model ferromagnetic metal is used to calculate the spin-polarization which occurs during inelastic electron-metal scattering with the production of an electron-hole pair. The polarization is found to have contributions from unequal spin-flip as well as non-flip energy loss rates. Our results indicate an asymmetry of the order of a few percent with parameters roughly modelling iron. (author)

Effect of Δ-isobar excitation on spin-dependent observables of elastic nucleon-deuteron scattering

International Nuclear Information System (INIS)

Nemoto, S.; Oryu, S.; Chmielewski, K.; Sauer, P.U.

2000-01-01

Δ-isobar excitation in the nuclear medium yields an effective three-nucleon force. A coupled-channel formulation with Δ-isobar excitation developed previously is used. The three-particle scattering equations are solved by a separable expansion of the two-baryon transition matrix for elastic nucleon-deuteron scattering. The effect of Δ-isobar excitation on the spin-dependent observables is studied at energies above 50 MeV nucleon lab energy. (author)

Evaluation at the medium energy region for Pb-208 and Bi-209

International Nuclear Information System (INIS)

Fukahori, Tokio; Pearlstein, S.

1991-01-01

Medium energy nuclear data in the 1--1000 MeV range is necessary to accelerator applications which include spallation neutron sources for radioactive waste treatment and accelerator shielding design, medical applications which include isotopes production and radiation therapy, and space applications. For the design of fission and fusion reactors, the nuclear data file for neutrons below 20 MeV is available and well evaluated. Evaluated nuclear data for protons and data in the medium energy region, however, have not been prepared completely. Evaluation in the medium energy region was performed using the theoretical calculation code ALICE-P or experimental data. In this paper, the evaluation of neutron and proton induced nuclear data for Pb-208 and Bi-209 has been performed using ALICE-P, empirical calculations and new systematics for the fission cross section. The evaluated data are compiled for possible inclusion in the ENDF/B-VI High Energy File. 204 refs., 51 figs., 9 tabs

Spin current evolution in the separated spin-up and spin-down quantum hydrodynamics

International Nuclear Information System (INIS)

Trukhanova, Mariya Iv.

2015-01-01

We have developed a method of quantum hydrodynamics (QHD) that describes particles with spin-up and with spin-down in separate. We have derived the equation of the spin current evolution as a part of the set of the quantum hydrodynamics equations that treat particles with different projection of spin on the preferable direction as two different species. We have studied orthogonal propagation of waves in the external magnetic field and determined the contribution of quantum corrections due to the Bohm potential and to magnetization energy of particles with different projections of spin in the spin-current wave dispersion. We have analyzed the limits of weak and strong magnetic fields. - Highlights: • We derive the spin current equation for particles with different projection of spin. • We predict the contribution of Bohm potential to the dynamics of spin current. • We derive the spin-current wave in the system of spin-polarized particles. • We study the propagation of spin-acoustic wave in magnetized dielectrics.

Spin-polarization and spin-flip in a triple-quantum-dot ring by using tunable lateral bias voltage and Rashba spin-orbit interaction

Energy Technology Data Exchange (ETDEWEB)

Molavi, Mohamad, E-mail: Mo_molavi@yahoo.com [Faculty of Physics, Kharazmi University, Tehran (Iran, Islamic Republic of); Faizabadi, Edris, E-mail: Edris@iust.ac.ir [School of Physics, Iran University of Science and Technology, 16846 Tehran (Iran, Islamic Republic of)

2017-04-15

By using the Green's function formalism, we investigate the effects of single particle energy levels of a quantum dot on the spin-dependent transmission properties through a triple-quantum-dot ring structure. In this structure, one of the quantum dots has been regarded to be non-magnetic and the Rashba spin-orbit interaction is imposed locally on this dot while the two others can be magnetic. The on-site energy of dots, manipulates the interference of the electron spinors that are transmitted to output leads. Our results show that the effects of magnetic dots on spin-dependent transmission properties are the same as the difference of on-site energies of the various dots, which is applicable by a controllable lateral bias voltage externally. Besides, by tuning the parameters such as Rashba spin-orbit interaction, and on-site energy of dots and magnetic flux inside the ring, the structure can be indicated the spin-flip effect and behave as a full spin polarizer or splitter. - Highlights: • The effects of magnetic dots on spin-dependent transmission properties are the same as the difference of on-site energies of the various dots. • In the situation that the QDs have non-zero on-site energies, the system can demonstrate the full spin-polarization. • By tuning the Rashba spin-orbit strength and magnetic flux encountered by the ring the system operates as a Stern-Gerlach apparatus.

Towards the improvement of spin-isospin properties in nuclear energy density functionals

International Nuclear Information System (INIS)

Roca-Maza, X.; Colò, G.; Liang, H. Z.; Sagawa, H.; Meng, J.; Ring, P.; Zhao, P. W.

2016-01-01

We address the problem of improving existing nuclear Energy Density Functionals (EDFs) in the spin-isospin channel. For that, we propose two different ways. The first one is to carefully take into account in the fitting protocol some of the key ground state properties for an accurate description of the most studied spin-isospin resonances: the Gamow-Teller Resonance (GTR) [1]. The second consists in providing a strategy to build local covariant EDF keeping the main features from their non-local counterparts [2]. The RHF model based on a Lagrangian where heavy mesons carry the nuclear effective interaction have been shown to be successful in the description of spin-isospin resonances [3]. (paper)

Graphene spin diode: Strain-modulated spin rectification

Energy Technology Data Exchange (ETDEWEB)

Wang, Yunhua; Wang, B., E-mail: stslyl@mail.sysu.edu.cn, E-mail: wangbiao@mail.sysu.edu.cn [Sino-French Institute of Nuclear Engineering and Technology, School of Physics and Engineering, State Key Laboratory of Optoelectronic Materials and Technologies, Sun Yat-sen University, Guangzhou 510275 (China); Liu, Yulan, E-mail: stslyl@mail.sysu.edu.cn, E-mail: wangbiao@mail.sysu.edu.cn [School of Engineering, Sun Yat-sen University, Guangzhou 510275 (China)

2014-08-04

Strain effects on spin transport in a ferromagnetic/strained/normal graphene junction are explored theoretically. It is shown that the spin-resolved Fermi energy range can be controlled by the armchair direction strain because the strain-induced pseudomagnetic field suppresses the current. The spin rectification effect for the bias reversal occurs because of a combination of ferromagnetic exchange splitting and the broken spatial symmetry of the junction. In addition, the spin rectification performance can be tuned remarkably by manipulation of the strains. In view of this strain-modulated spin rectification effect, we propose that the graphene-based ferromagnetic/strained/normal junction can be used as a tunable spin diode.

Medium-term energy hub management subject to electricity price and wind uncertainty

International Nuclear Information System (INIS)

Najafi, Arsalan; Falaghi, Hamid; Contreras, Javier; Ramezani, Maryam

2016-01-01

Highlights: • A new model for medium-term energy hub management is proposed. • Risk aversion is considered in medium-term energy hub management. • Stochastic programing is used to solve the medium-term energy hub management problem. • Electricity price and wind uncertainty are considered. - Abstract: Energy hubs play an important role in implementing multi-carrier energy systems. More studies are required in both their modeling and operating aspects. In this regard, this paper attempts to develop medium-term management of an energy hub in restructured power systems. A model is presented to manage an energy hub which has electrical energy and natural gas as inputs and electrical and heat energy as outputs. Electricity is procured in various ways, either purchasing it from a pool-based market and bilateral contracts, or producing it from a Combined Heat and Power (CHP) unit, a diesel generator unit and Wind Turbine Generators (WTGs). Pool prices and wind turbine production are subject to uncertainty, which makes energy management a complex puzzle. Heat demand is also procured by a furnace and a CHP unit. Energy hub managers should make decisions whether to purchase electricity from the electricity market and gas from the gas network or to produce electricity using a set of generators to meet the electrical and heat demands in the presence of uncertainties. The energy management objective is to minimize the total cost subject to several technical constraints using stochastic programming. Conditional Value at Risk (CVaR), a well-known risk measure, is used to reduce the unfavorable risk of costs. In doing so, the proposed model is illustrated using a sample test case with actual prices, load and wind speed data. The results show that the minimum cost is obtained by the best decisions involving the electricity market and purchasing natural gas for gas facilities. Considering risk also increases the total expected cost and decreases the CVaR.

An overview of spin physics

International Nuclear Information System (INIS)

Prescott, C.Y.

1991-07-01

Spin physics is playing an increasingly important role in high energy experiments and theory. This review looks at selected topics in high energy spin physics that were discussed at the 9th International Symposium on High Energy Spin Physics at Bonn in September 1990

Angle and frequency dependence of self-energy from spin fluctuation mediated d-wave pairing for high temperature superconductors.

Science.gov (United States)

Hong, Seung Hwan; Choi, Han-Yong

2013-09-11

We investigated the characteristics of spin fluctuation mediated superconductivity employing the Eliashberg formalism. The effective interaction between electrons was modeled in terms of the spin susceptibility measured by inelastic neutron scattering experiments on single crystal La(2-x)Sr(x)CuO4 superconductors. The diagonal self-energy and off-diagonal self-energy were calculated by solving the coupled Eliashberg equation self-consistently for the chosen spin susceptibility and tight-binding dispersion of electrons. The full momentum and frequency dependence of the self-energy is presented for optimally doped, overdoped, and underdoped LSCO cuprates in a superconductive state. These results may be compared with the experimentally deduced self-energy from ARPES experiments.

Frequency and wavenumber selective excitation of spin waves through coherent energy transfer from elastic waves

OpenAIRE

Hashimoto, Yusuke; Bossini, Davide; Johansen, Tom H.; Saitoh, Eiji; Kirilyuk, Andrei; Rasing, Theo

2017-01-01

Using spin-wave tomography (SWaT), we have investigated the excitation and the propagation dynamics of optically-excited magnetoelastic waves, i.e. hybridized modes of spin waves and elastic waves, in a garnet film. By using time-resolved SWaT, we reveal the excitation dynamics of magnetoelastic waves through coherent-energy transfer between optically-excited pure-elastic waves and spin waves via magnetoelastic coupling. This process realizes frequency and wavenumber selective excitation of s...

Angular distribution of scattered electron and medium energy electron spectroscopy for metals

International Nuclear Information System (INIS)

Oguri, Takeo; Ishioka, Hisamichi; Fukuda, Hisashi; Irako, Mitsuhiro

1986-01-01

The angular distribution (AD) of scattered electrons produced by medium energy incident electrons (E P = 50 ∼ 300 eV) from polycrystalline Ti, Fe, Ni, Cu and Au were obtained by the angle-resolved medium energy electron spectrometer. The AD of the energy loss peaks are similar figures to AD of the elastically reflected electron peaks. Therefore, the exchanged electrons produced by the knock-on collision between the incident electrons and those of metals without momentum transfer are observed as the energy loss spectra (ELS). This interpretation differs from the inconsequent interpretation by the dielectric theory or the interband transition. The information depth and penetration length are obtained from AD of the Auger electron peaks. The contribution of the surface to spectra is 3 % at the maximum for E P = 50 eV. The true secondary peaks representing the secondary electron emission spectroscopy (SES) are caused by the emissions of the energetic electrons (kT e ≥ 4 eV), and SES is the inversion of ELS. The established fundamental view is that the medium energy electron spectra represent the total bulk density of states. (author)

Medium energy measurements of n-n parameters. Progress report, January 1-December 31, 1985

International Nuclear Information System (INIS)

1986-01-01

This document constitutes a progress report (1985-86) for the ongoing medium energy nuclear physics research program. A major part of the work has been and will continue to be associated with research done at the Nucleon Physics Laboratory (NPL) at the Los Alamos Meson Physics Facility (LAMPF). The aim of the experimental program is the determination of the nucleon-nucleon amplitudes at medium energy. The required data include both elastic and inelastic experiments, and in addition the measurement of polarization and polarization transfer parameters. We have been emphasizing single pion production measurements using polarized proton beams, and expect that our present data base will provide stringent tests of theoretical models. With the development of the LAMPF high intensity polarized proton source, we expect that a reasonably intense beam of medium energy polarized neutrons will become available, and are planning a series of experiments utilizing polarized neutrons to determine the importance of the I = 0 reaction amplitudes at medium energies

The straintronic spin-neuron

International Nuclear Information System (INIS)

Biswas, Ayan K; Bandyopadhyay, Supriyo; Atulasimha, Jayasimha

2015-01-01

In artificial neural networks, neurons are usually implemented with highly dissipative CMOS-based operational amplifiers. A more energy-efficient implementation is a ‘spin-neuron’ realized with a magneto-tunneling junction (MTJ) that is switched with a spin-polarized current (representing weighted sum of input currents) that either delivers a spin transfer torque or induces domain wall motion in the soft layer of the MTJ to mimic neuron firing. Here, we propose and analyze a different type of spin-neuron in which the soft layer of the MTJ is switched with mechanical strain generated by a voltage (representing weighted sum of input voltages) and term it straintronic spin-neuron. It dissipates orders of magnitude less energy in threshold operations than the traditional current-driven spin neuron at 0 K temperature and may even be faster. We have also studied the room-temperature firing behaviors of both types of spin neurons and find that thermal noise degrades the performance of both types, but the current-driven type is degraded much more than the straintronic type if both are optimized for maximum energy-efficiency. On the other hand, if both are designed to have the same level of thermal degradation, then the current-driven version will dissipate orders of magnitude more energy than the straintronic version. Thus, the straintronic spin-neuron is superior to current-driven spin neurons. (paper)

Resonant Tunneling Spin Pump

Science.gov (United States)

Ting, David Z.

2007-01-01

The resonant tunneling spin pump is a proposed semiconductor device that would generate spin-polarized electron currents. The resonant tunneling spin pump would be a purely electrical device in the sense that it would not contain any magnetic material and would not rely on an applied magnetic field. Also, unlike prior sources of spin-polarized electron currents, the proposed device would not depend on a source of circularly polarized light. The proposed semiconductor electron-spin filters would exploit the Rashba effect, which can induce energy splitting in what would otherwise be degenerate quantum states, caused by a spin-orbit interaction in conjunction with a structural-inversion asymmetry in the presence of interfacial electric fields in a semiconductor heterostructure. The magnitude of the energy split is proportional to the electron wave number. Theoretical studies have suggested the possibility of devices in which electron energy states would be split by the Rashba effect and spin-polarized currents would be extracted by resonant quantum-mechanical tunneling.

High energy spin waves in iron measured by neutron scattering

International Nuclear Information System (INIS)

Boothroyd, A.T.; Paul, D.M.; Mook, H.A.

1991-01-01

We present new results for the spin were dispersion relation measured along the [ζζ0] direction in bcc iron (12% silicon) by time-of-flight, neutron inelastic scattering. The excitations were followed to the zone boundary, where they are spread over a range of energies around 300meV. 6 refs., 2 figs

The angular dependence of spin-state energy splittings in the ? core

Science.gov (United States)

Groß, Lynn; Steenbock, Torben; Herrmann, Carmen

2013-07-01

Spin-state energy splittings are highly relevant for catalysis, molecular magnetism, and materials science, yet continue to pose a challenge for electronic structure methods. For a Fe2O2+ 2 core, we evaluate the bridging angle dependence of energy splittings between ferromagnetically and antiferromagnetically coupled states for different exchange-correlation functionals, and compare with complete active space self-consistent field (CASSCF) values, also including second-order perturbative corrections (CASPT2). CASSCF and CASPT2 yield strong antiferromagnetic coupling, with the smallest coupling at 100°, and a smooth dependence on the angle for Fe-O-Fe angles of 70° to 120°. Interestingly, this is qualitatively the same behaviour as often found for stable dinuclear transition metal complexes. While all functionals show the same angular dependence as CASPT2, they favour the antiferromagnetic state less strongly. Pure functionals such as BP86, BLYP, SSB-D, and TPSS come closer to the CASPT2 results (with energy splittings by about 60 kJ/mol smaller than the CASPT2 ones) than hybrid functionals. The hybrid functionals B3LYP, B3LYP⋆, and PBE0 favour the antiferromagnetic state even less strongly, resulting in ferromagnetic coupling for angles around 100°. The good qualitative agreement between CASPT2 and CASSCF on the one hand and CASPT2 and density functional theory on the other hand for angles between 70° and 110° suggests that the chosen active space of 18 electrons in 14 orbitals may be adequate for spin-state energy splitting of Fe2O2+ 2 in that region (possibly due to error cancellation), while angles of 60° or 120° may require larger active spaces. This study is complemented by an analysis of local spins, local charges, and CASSCF natural orbitals.

Development of a Telescope for Medium-Energy Gamma-ray Astronomy

Science.gov (United States)

Sunter, Stan

2012-01-01

Since the launch of AGILE and FERMI, the scientific progress in high-energy (Eg greater than approximately 200 MeV) gamma-ray science has been, and will continue to be dramatic. Both of these telescopes cover a broad energy range from approximately 20 MeV to greater than 10 GeV. However, neither instrument is optimized for observations below approximately 200 MeV where many astrophysical objects exhibit unique, transitory behavior, such as spectral breaks, bursts, and flares. Hence, while significant progress from current observations is expected, there will nonetheless remain a significant sensitivity gap in the medium-energy (approximately 0.1-200 MeV) regime; the lower end of this range remains largely unexplored whereas the upper end will allow comparison with FERMI data. Tapping into this unexplored regime requires significant improvements in sensitivity. A major emphasis of modern detector development, with the goal of providing significant improvements in sensitivity in the medium-energy regime, focuses on high-resolution electron tracking. The Three-Dimensional Track Imager (3-DTI) technology being developed at GSFC provides high resolution tracking of the electron-positron pair from gamma-ray interactions from 5 to 200 MeV. The 3-DTI consists of a time projection chamber (TPC) and 2-D cross-strip microwell detector (MWD). The low-density and homogeneous design of the 3-DTI, offers unprecedented sensitivity by providing angular resolution near the kinematic limit. Electron tracking also enables measurement of gamma-ray polarization, a new tool to study astrophysical phenomenon. We describe the design, fabrication, and performance of a 30x30x30 cm3 3-DTI detector prototype of a medium-energy gamma-ray telescope.

Refinement of the AdEPT Medium-Energy Gamma-Ray Science

Data.gov (United States)

National Aeronautics and Space Administration — We propose to explore the theoretical framework for the relatively unexplored field of medium energy (5--200 MeV) gamma-ray astronomy for a mission concept...

Renormalized Stress-Energy Tensor of an Evaporating Spinning Black Hole.

Science.gov (United States)

Levi, Adam; Eilon, Ehud; Ori, Amos; van de Meent, Maarten

2017-04-07

We provide the first calculation of the renormalized stress-energy tensor (RSET) of a quantum field in Kerr spacetime (describing a stationary spinning black hole). More specifically, we employ a recently developed mode-sum regularization method to compute the RSET of a minimally coupled massless scalar field in the Unruh vacuum state, the quantum state corresponding to an evaporating black hole. The computation is done here for the case a=0.7M, using two different variants of the method: t splitting and φ splitting, yielding good agreement between the two (in the domain where both are applicable). We briefly discuss possible implications of the results for computing semiclassical corrections to certain quantities, and also for simulating dynamical evaporation of a spinning black hole.

Tunnel spin polarization versus energy for clean and doped Al2O3 barriers

NARCIS (Netherlands)

Park, B.G.; Banerjee, T.; Lodder, J.C.; Jansen, R.

2007-01-01

The variation of the tunnel spin-polarization (TSP) with energy is determined using a magnetic tunnel transistor, allowing quantification of the energy dependent TSP separately for both ferromagnet/insulator interfaces and direct correlation with the tunnel magnetoresistance (TMR) measured in the

Tunnel Spin Polarization Versus Energy for Clean and Doped Al2O3 Barriers

NARCIS (Netherlands)

Park, B.G.; Banerjee, T.; Lodder, J.C.; Jansen, R.

2007-01-01

The variation of the tunnel spin-polarization (TSP) with energy is determined using a magnetic tunnel transistor, allowing quantification of the energy dependent TSP separately for both ferromagnet/insulator interfaces and direct correlation with the tunnel magnetoresistance (TMR) measured in the

Calculation of the binding energy per nucleon and the quasi-particle interation in nuclear matter under consideration of relativistic medium effects

International Nuclear Information System (INIS)

Hippchen, T.

1985-12-01

In a first part, nuclear matter calculations have been performed in the Dirac-Brueckner approach using a) a nucleon-nucleon potential of one-boson-exchange (OBE) type and b) a more realistic interaction in which the fictitious σ-exchange of the OBE-model is replaced by explicit 2π- and πρ-exchange diagrams. Both potential models yield the correct empirical binding energy and saturation density. It turns out that the total sum of relativistic effects caused by the emplicit 2 π- and πρ-exchanges is comparable to those due to σ-exchange. In a second part, the nuclear quasiparticle interaction, i.e. the Landau parameters, have been calculated in the central (F), isospin (F'), spin (G) and spin-isospin (G') channel, in an analogous way. Compared to nonrelativistic calculations (including conventional medium corrections like Pauli and dispersion effects), a strong improvement has been found, especially in the F- and G-channel. Finally, the influence of A 1 -exchange is studied, in NN scattering and in nuclear matter. It turns out that, after a suitable and necessary readjustment of some meson parameters, its role is negligibly small. (orig.)

Spin-polaron theory of high-Tc superconductivity: I, spin polarons and high-Tc pairing

International Nuclear Information System (INIS)

Wood, R.F.

1993-06-01

The concept of a spin polaron is introduced and contrasted with the more familiar ionic polaron picture. A brief review of aspects of ionic bipolaronic superconductivity is given with particular emphasis on the real-space pairing and true Bose condensation characteristics. The formation energy of spin polarons is then calculated in analogy with ionic polarons. The spin-flip energy of a Cu spin in an antiferromagnetically aligned CuO 2 plane is discussed. It is shown that the introduction of holes into the CuO 2 planes will always lead to the destruction of long-range AF ordering due to the formation of spin polarons. The pairing of two spin polarons can be expected because of the reestablishment of local (short-range) AF ordering; the magnitude of the pairing energy is estimated using a simplified model. The paper closes with a brief discussion of the formal theory of spin polarons

Anomalous scattering of neutrons in spin-polarized media

International Nuclear Information System (INIS)

Bashkin, E.P.

1989-01-01

A new exchange mechanism of inelastic scattering with spin flip for slow neutrons propagating through a spin-polarized medium is studied. The scattering is accompanied by emission or absorption of thermal fluctuations of the transverse magnetization of the medium; the weakly damped Larmor precession of nuclear spins in the external magnetic field plays the main role in these fluctuations. Under the conditions of giant opalescence the effect is enormous and the corresponding cross sections are significantly greater than the standard elastic scattering cross sections. Thus in the case of 29 Si↑ and 3 He↑ under typical experimental conditions the cross sections of these inelastic processes are of the order of 10 5 -10 6 b

Quantum dot as spin current generator and energy harvester

Science.gov (United States)

Szukiewicz, Barbara; Wysokiński, Karol I.

2015-05-01

The thermoelectric transport in the device composed of a central nanoscopic system in contact with two electrodes and subject to the external magnetic field of Zeeman type has been studied. The device can support pure spin current in the electrodes and may serve as a source of the temperature induced spin currents with possible applications in spintronics. The system may also be used as an energy harvester. We calculate its thermodynamic efficiency η and the power output P. The maximal efficiency of the device reaches the Carnot value when the device works reversibly but with the vanishing power. The interactions between carriers diminish the maximal efficiency of the device, which under the constant load drops well below the Carnot limit but may exceed the Curzon-Ahlborn limit. While the effect of intradot Coulomb repulsion on η depends on the parameters, the interdot/interlevel interaction strongly diminishes the device efficiency.

Medium effects in DIS from polarized nuclear targets

Energy Technology Data Exchange (ETDEWEB)

Fanchiotti, Huner; Garcia Canal, Carlos A.; Tarutina, Tatiana [Universidad Nacional de La Plata, Departamento de Fisica, C.C. 67, La Plata (Argentina); Universidad Nacional de La Plata, IFLP(CONICET), C.C. 67, La Plata (Argentina); Vento, Vicente [Universidad de Valencia, Consejo Superior de Investigaciones Cientificas, Departamento de Fisica Teorica and Instituto de Fisica Corpuscular, Burjassot (Valencia) (Spain)

2014-07-15

The behavior of the nucleon structure functions in lepton nuclei deep inelastic scattering, both polarized and unpolarized, due to nuclear structure effects is reanalyzed. The study is performed in two schemes: an x-rescaling approach, and one in which there is an increase of sea quark components in the in-medium nucleon, related to the low-energy N-N interaction. In view of a recent interesting experimental proposal to study the behavior of the proton spin structure functions in nuclei we proceed to compare these approaches in an effort to enlighten the possible phenomenological interest of such difficult experiment. (orig.)

A study of the deep structure of the energy landscape of glassy polystyrene: the exponential distribution of the energy barriers revealed by high-field electron spin resonance spectroscopy

International Nuclear Information System (INIS)

Bercu, V; Martinelli, M; Massa, C A; Pardi, L A; Leporini, D

2004-01-01

The reorientation of one small paramagnetic molecule (spin probe) in glassy polystyrene (PS) is studied by high-field electron spin resonance spectroscopy at two different Larmor frequencies (190 and 285 GHz). The exponential distribution of the energy barriers for the rotational motion of the spin probe is unambiguously evidenced at both 240 and 270 K. The same shape for the distribution of the energy barriers of PS was evidenced by the master curves provided by previous mechanical and light scattering studies. The breadth of the energy barrier distribution of the spin probe is in the range of the estimates of the breadth of the PS energy barrier distribution. The evidence that the deep structure of the energy landscape of PS exhibits the exponential shape of the energy barrier distribution agrees with the results from extreme-value statistics (Bouchaud and Mezard 1997 J. Phys. A: Math. Gen. 30 7997) and the trap model by Bouchaud and co-workers (1996 J. Phys. A: Math. Gen. 29 3847, 2001 Phys. Rev. B 64 104417). (letter to the editor)

Transport calculation of medium-energy protons and neutrons by Monte Carlo method

International Nuclear Information System (INIS)

Ban, Syuuichi; Hirayama, Hideo; Katoh, Kazuaki.

1978-09-01

A Monte Carlo transport code, ARIES, has been developed for protons and neutrons at medium energy (25 -- 500 MeV). Nuclear data provided by R.G. Alsmiller, Jr. were used for the calculation. To simulate the cascade development in the medium, each generation was represented by a single weighted particle and an average number of emitted particles was used as the weight. Neutron fluxes were stored by the collisions density method. The cutoff energy was set to 25 MeV. Neutrons below the cutoff were stored to be used as the source for the low energy neutron transport calculation upon the discrete ordinates method. Then transport calculations were performed for both low energy neutrons (thermal -- 25 MeV) and secondary gamma-rays. Energy spectra of emitted neutrons were calculated and compared with those of published experimental and calculated results. The agreement was good for the incident particles of energy between 100 and 500 MeV. (author)

More spinoff from spin

International Nuclear Information System (INIS)

Masaike, Akira

1993-01-01

Despite playing a major role in today's Standard Model, spin - the intrinsic angular momentum carried by particles - is sometimes dismissed as an inessential complication. However several major spin questions with important implications for the Standard Model remain unanswered, and recent results and new technological developments made the 10th International Symposium on High Energy Spin Physics, held in Nagoya, Japan, in November, highly topical. The symposium covered a wide range of physics, reflecting the diversity of spin effects, however four main themes were - the spin content of the nucleon, tests of symmetries and physics beyond standard models, intermediate energy physics, and spin technologies. Opening the meeting, T. Kinoshita reviewed the status of measurements of the anomalous magnetic moment (g-2) of the electron and the muon. The forthcoming experiment at Brookhaven (September 1991, page 23) will probe beyond the energy ranges open to existing electronpositron colliders. For example muon substructure will be opened up to 5 TeV and Ws to 2 TeV. R.L. Jaffe classified quark-parton distributions in terms of their spin dependence, pointing out their leftright attributes, and emphasized the importance of measuring transverse spin distributions through lepton pair production

Quantum Computing with an Electron Spin Ensemble

DEFF Research Database (Denmark)

Wesenberg, Janus; Ardavan, A.; Briggs, G.A.D.

2009-01-01

We propose to encode a register of quantum bits in different collective electron spin wave excitations in a solid medium. Coupling to spins is enabled by locating them in the vicinity of a superconducting transmission line cavity, and making use of their strong collective coupling to the quantized...

Spinning Eggs and Ballerinas

Science.gov (United States)

Cross, Rod

2013-01-01

Measurements are presented on the rise of a spinning egg. It was found that the spin, the angular momentum and the kinetic energy all decrease as the egg rises, unlike the case of a ballerina who can increase her spin and kinetic energy by reducing her moment of inertia. The observed effects can be explained, in part, in terms of rolling friction…

MEGA - A next generation mission in Medium Energy Gamma-Ray Astronomy

International Nuclear Information System (INIS)

Kanbach, Gottfried

2001-01-01

A Medium Energy Gamma-Ray Astronomy (MEGA) detector is being developed and proposed for a small satellite mission. MEGA intends to improve the sensitivity at medium γ-ray energies (0.4-50 MeV) by at least an order of magnitude with respect to past instruments. Its large field of view will be especially important for the discovery of transient sources and for conducting all-sky surveys. Key science objectives for MEGA are the investigation of cosmic high-energy accelerators and of nucleosynthesis sites with γ-ray lines. The large-scale structure of the galactic and cosmic diffuse background is another important goal for this mission. MEGA records and images γ-ray events by completely tracking Compton and pair creation interactions in a stack of double sided Si-strip track detectors and 3-D resolving CsI calorimeters

Low energy spin excitations in chromium metal

International Nuclear Information System (INIS)

Pynn, R.; Azuah, R.T.; Stirling, W.G.

1997-01-01

Neutron scattering experiments with full polarization analysis have been performed with a single crystal of chromium to study the low-energy spin fluctuations in the transverse spin density wave (TSDW) state. A number of remarkable results have been found. Inelastic scattering observed close to the TSDW satellite positions at (1 ± δ,0,0) does not behave as expected for magnon scattering. In particular, the scattering corresponds to almost equally strong magnetization fluctuations both parallel and perpendicular to the ordered moments of the TSDW phase. As the Neel temperature is approached from below, scattering at the commensurate wavevector (1,0,0) increases in intensity as a result of critical scattering at silent satellites (1,0, ± δ) being included within the spectrometer resolution function. This effect, first observed by Sternlieb et al, does not account for all of the inelastic scattering around the (1,0,0) position, however, Rather, there are further collective excitations, apparently emanating from the TSDW satellites, which correspond to magnetic fluctuations parallel to the ordered TSDW moments. These branches have a group velocity that is close to that of (1,0,0) longitudinal acoustic (LA) phonons, but assigning their origin to magneto-elastic scattering raises other unanswered questions

Spin rotation after a spin-independent scattering. Spin properties of an electron gas in a solid

International Nuclear Information System (INIS)

Zayets, V.

2014-01-01

It is shown that spin direction of an electron may not be conserved after a spin-independent scattering. The spin rotations occur due to a quantum-mechanical fact that when a quantum state is occupied by two electrons of opposite spins, the total spin of the state is zero and the spin direction of each electron cannot be determined. It is shown that it is possible to divide all conduction electrons into two group distinguished by their time-reversal symmetry. In the first group the electron spins are all directed in one direction. In the second group there are electrons of all spin directions. The number of electrons in each group is conserved after a spin-independent scattering. This makes it convenient to use these groups for the description of the magnetic properties of conduction electrons. The energy distribution of spins, the Pauli paramagnetism and the spin distribution in the ferromagnetic metals are described within the presented model. The effects of spin torque and spin-torque current are described. The origin of spin-transfer torque is explained within the presented model

Spin-spin cross relaxation and spin-Hamiltonian spectroscopy by optical pumping of Pr/sup 3+/:LaF3

International Nuclear Information System (INIS)

Lukac, M.; Otto, F.W.; Hahn, E.L.

1989-01-01

We report the observation of an anticrossing in solid-state laser spectroscopy produced by cross relaxation. Spin-spin cross relaxation between the /sup 141/Pr- and /sup 19/F-spin reservoirs in Pr/sup 3+/:LaF 3 and its influence on the /sup 141/Pr NMR spectrum is detected by means of optical pumping. The technique employed combines optical pumping and hole burning with either external magnetic field sweep or rf resonance saturation in order to produce slow transient changes in resonant laser transmission. At a certain value of the external Zeeman field, where the energy-level splittings of Pr and F spins match, a level repulsion and discontinuity of the Pr/sup 3+/ NMR lines is observed. This effect is interpreted as the ''anticrossing'' of the combined Pr-F spin-spin reservoir energy states. The Zeeman-quadrupole-Hamiltonian spectrum of the hyperfine optical ground states of Pr/sup 3+/:LaF 3 is mapped out over a wide range of Zeeman magnetic fields. A new scheme is proposed for dynamic polarization of nuclei by means of optical pumping, based on resonant cross relaxation between rare spins and spin reservoirs

Medium energy hadron scattering from nuclei

International Nuclear Information System (INIS)

Ginocchio, J.N.; Wenes, G.

1986-01-01

The Glauber approximation for medium energy scattering of hadronic projectiles from nuclei is combined with the interacting boson model of nuclei to produce a transition matrix for elastic and inelastic scattering in algebraic form which includes coupling to all the intermediate states. We present closed form analytic expresions for the transition matrix elements for the three dynamical symmetries of the interacting boson model; that is for, a spherical quadrupole vibrator, a γ unstable rotor, and both prolate and oblate axially symmetric rotors. We give examples of application of this formalism to proton scattering from 154 Sm and 154 Gd. 27 refs., 5 figs., 1 tab

Quantum Spin Lenses in Atomic Arrays

Directory of Open Access Journals (Sweden)

A. W. Glaetzle

2017-09-01

Full Text Available We propose and discuss quantum spin lenses, where quantum states of delocalized spin excitations in an atomic medium are focused in space in a coherent quantum process down to (essentially single atoms. These can be employed to create controlled interactions in a quantum light-matter interface, where photonic qubits stored in an atomic ensemble are mapped to a quantum register represented by single atoms. We propose Hamiltonians for quantum spin lenses as inhomogeneous spin models on lattices, which can be realized with Rydberg atoms in 1D, 2D, and 3D, and with strings of trapped ions. We discuss both linear and nonlinear quantum spin lenses: in a nonlinear lens, repulsive spin-spin interactions lead to focusing dynamics conditional to the number of spin excitations. This allows the mapping of quantum superpositions of delocalized spin excitations to superpositions of spatial spin patterns, which can be addressed by light fields and manipulated. Finally, we propose multifocal quantum spin lenses as a way to generate and distribute entanglement between distant atoms in an atomic lattice array.

Space-time picture of relativistic propagation of medium energy hadrons through nuclei

International Nuclear Information System (INIS)

Bleszynski, M.; Jaroszewicz, T.

1985-01-01

Relativistic virtual pair creation effects in hadron-nucleus scattering at medium energies are discussed. A close analogy is found between these effects (particle propagation backwards in time) and some of noneikonal correlations to the Glauber theory, arising from particle propagation backwards in space. In multiple scattering both effects appear only for configurations involving overlapping scatterers and lead to the non-additivity of phase shifts. The proper-time path-integral formalism is found to provide an intuitive geometrical picture of these phenomena. The relativistic corrections are estimated to be of the order k/(aE/sup 2/), k being the particle momentum, E its energy, and a the target size. At medium energies they are comparable to noneikonal corrections, of order 1/(ak). Both effects vanish at high energy, when particle propagation in space-time can be described by means of geometrical optics

Inelastic collisions of medium energy atomic elements. Qualitative model of energy losses during collisions

International Nuclear Information System (INIS)

Pustovit, A.N.

2006-01-01

A new approach to the theoretical description of energy losses of atomic particle of medium energy during their interaction with the substance is proposed. The corner-stone of this approach is the supposition that all of the collision processes have inelastic nature during particle movement through the substance, while the calculation of the atomic particles braking is based on the law of their dispersion and the laws of energy and momentum conservation at the inelastic collisions. It is shown that inelastic atomic collision there are three dispersion zones for the only potential interaction with different laws, which characterize energy losses. The application conditions of this approach are determined [ru

Spin Relaxation and Manipulation in Spin-orbit Qubits

Science.gov (United States)

Borhani, Massoud; Hu, Xuedong

2012-02-01

We derive a generalized form of the Electric Dipole Spin Resonance (EDSR) Hamiltonian in the presence of the spin-orbit interaction for single spins in an elliptic quantum dot (QD) subject to an arbitrary (in both direction and magnitude) applied magnetic field. We predict a nonlinear behavior of the Rabi frequency as a function of the magnetic field for sufficiently large Zeeman energies, and present a microscopic expression for the anisotropic electron g-tensor. Similarly, an EDSR Hamiltonian is devised for two spins confined in a double quantum dot (DQD). Finally, we calculate two-electron-spin relaxation rates due to phonon emission, for both in-plane and perpendicular magnetic fields. Our results have immediate applications to current EDSR experiments on nanowire QDs, g-factor optimization of confined carriers, and spin decay measurements in DQD spin-orbit qubits.

Spin-1/2 particles in non-inertial reference frames. Low- and high-energy approximations

International Nuclear Information System (INIS)

Singh, D.; Papini, G.

2000-01-01

Spin-1/2 particles can be used to study inertial and gravitational effects by means of interferometers, particle accelerators, and ultimately quantum systems. These studies require, in general, knowledge of the Hamiltonian and of the inertial and gravitational quantum phases. The procedure followed gives both in the low- and high-energy approximations. The latter affords a more consistent treatment of mass at high energies. The procedure is based on general relativity and on a solution of the Dirac equation that is exact to first-order in the metric deviation. Several previously known acceleration- and rotation-induced effects are rederived in a comprehensive, unified way. Several new effects involve spin, electromagnetic and inertial/gravitational fields in different combinations

Direct observation and theory of trajectory-dependent electronic energy losses in medium-energy ion scattering.

Science.gov (United States)

Hentz, A; Parkinson, G S; Quinn, P D; Muñoz-Márquez, M A; Woodruff, D P; Grande, P L; Schiwietz, G; Bailey, P; Noakes, T C Q

2009-03-06

The energy spectrum associated with scattering of 100 keV H+ ions from the outermost few atomic layers of Cu(111) in different scattering geometries provides direct evidence of trajectory-dependent electronic energy loss. Theoretical simulations, combining standard Monte Carlo calculations of the elastic scattering trajectories with coupled-channel calculations to describe inner-shell ionization and excitation as a function of impact parameter, reproduce the effects well and provide a means for far more complete analysis of medium-energy ion scattering data.

Spin-Caloritronic Batteries

DEFF Research Database (Denmark)

Yu, Xiao-Qin; Zhu, Zhen-Gang; Su, Gang

2017-01-01

The thermoelectric performance of a topological energy converter is analyzed. The H-shaped device is based on a combination of transverse topological effects involving the spin: the inverse spin Hall effect and the spin Nernst effect. The device can convert a temperature drop in one arm into an e...

Spin Orbit Interaction Engineering for beyond Spin Transfer Torque memory

Science.gov (United States)

Wang, Kang L.

Spin transfer torque memory uses electron current to transfer the spin torque of electrons to switch a magnetic free layer. This talk will address an alternative approach to energy efficient non-volatile spintronics through engineering of spin orbit interaction (SOC) and the use of spin orbit torque (SOT) by the use of electric field to improve further the energy efficiency of switching. I will first discuss the engineering of interface SOC, which results in the electric field control of magnetic moment or magneto-electric (ME) effect. Magnetic memory bits based on this ME effect, referred to as magnetoelectric RAM (MeRAM), is shown to have orders of magnitude lower energy dissipation compared with spin transfer torque memory (STTRAM). Likewise, interests in spin Hall as a result of SOC have led to many advances. Recent demonstrations of magnetization switching induced by in-plane current in heavy metal/ferromagnetic heterostructures have been shown to arise from the large SOC. The large SOC is also shown to give rise to the large SOT. Due to the presence of an intrinsic extraordinarily strong SOC and spin-momentum lock, topological insulators (TIs) are expected to be promising candidates for exploring spin-orbit torque (SOT)-related physics. In particular, we will show the magnetization switching in a chromium-doped magnetic TI bilayer heterostructure by charge current. A giant SOT of more than three orders of magnitude larger than those reported in heavy metals is also obtained. This large SOT is shown to come from the spin-momentum locked surface states of TI, which may further lead to innovative low power applications. I will also describe other related physics of SOC at the interface of anti-ferromagnetism/ferromagnetic structure and show the control exchange bias by electric field for high speed memory switching. The work was in part supported by ERFC-SHINES, NSF, ARO, TANMS, and FAME.

Theoretical studies in medium-energy nuclear and hadronic physics. [Indiana Univ. Nuclear Theory Center and Department of Physics

Energy Technology Data Exchange (ETDEWEB)

Horowitz, C J; Macfarlane, M H; Matsui, T; Serot, B D

1993-01-01

A proposal for theoretical nuclear physics research is made for the period April 1, 1993 through March 31, 1996. Research is proposed in the following areas: relativistic many-body theory of nuclei and nuclear matter, quasifree electroweak scattering and strange quarks in nuclei, dynamical effects in (e,e[prime]p) scattering at large momentum transfer, investigating the nucleon's parton sea with polarized leptoproduction, physics of ultrarelativistic nucleus[endash]nucleus collisions, QCD sum rules and hadronic properties, non-relativistic models of nuclear reactions, and spin and color correlations in a quark-exchange model of nuclear matter. Highlights of recent research, vitae of principal investigators, and lists of publications and invited talks are also given. Recent research dealt primarily with medium-energy nuclear physics, relativistic theories of nuclei and the nuclear response, the nuclear equation of state under extreme conditions, the dynamics of the quark[endash]gluon plasma in relativistic heavy-ion collisions, and theories of the nucleon[endash]nucleon force.

Logical spin-filtering in a triangular network of quantum nanorings with a Rashba spin-orbit interaction

Science.gov (United States)

Dehghan, E.; Sanavi Khoshnoud, D.; Naeimi, A. S.

2018-01-01

The spin-resolved electron transport through a triangular network of quantum nanorings is studied in the presence of Rashba spin-orbit interaction (RSOI) and a magnetic flux using quantum waveguide theory. This study illustrates that, by tuning Rashba constant, magnetic flux and incoming electron energy, the triangular network of quantum rings can act as a perfect logical spin-filtering with high efficiency. By changing in the energy of incoming electron, at a proper value of the Rashba constant and magnetic flux, a reverse in the direction of spin can take place in the triangular network of quantum nanorings. Furthermore, the triangular network of quantum nanorings can be designed as a device and shows several simultaneous spintronic properties such as spin-splitter and spin-inverter. This spin-splitting is dependent on the energy of the incoming electron. Additionally, different polarizations can be achieved in the two outgoing leads from an originally incoming spin state that simulates a Stern-Gerlach apparatus.

Selective coupling of individual electron and nuclear spins with integrated all-spin coherence protection

Science.gov (United States)

Terletska, Hanna; Dobrovitski, Viatcheslav

2015-03-01

The electron spin of the NV center in diamond is a promising platform for spin sensing. Applying the dynamical decoupling, the NV electron spin can be used to detect the individual weakly coupled carbon-13 nuclear spins in diamond and employ them for small-scale quantum information processing. However, the nuclear spins within this approach remain unprotected from decoherence, which ultimately limits the detection and restricts the fidelity of the quantum operation. Here we investigate possible schemes for combining the resonant decoupling on the NV spin with the decoherence protection of the nuclear spins. Considering several schemes based on pulse and continuous-wave decoupling, we study how the joint electron-nuclear spin dynamics is affected. We identify regimes where the all-spin coherence protection improves the detection and manipulation. We also discuss potential applications of the all-spin decoupling for detecting spins outside diamond, with the purpose of implementing the nanoscale NMR. This work was supported by the US Department of Energy Basic Energy Sciences (Contract No. DE-AC02-07CH11358).

QED approach to the nuclear spin-spin coupling tensor

International Nuclear Information System (INIS)

Romero, Rodolfo H.; Aucar, Gustavo A.

2002-01-01

A quantum electrodynamical approach for the calculation of the nuclear spin-spin coupling tensor of nuclear-magnetic-resonance spectroscopy is given. Quantization of radiation fields within the molecule is considered and expressions for the magnetic field in the neighborhood of a nucleus are calculated. Using a generalization of time-dependent response theory, an effective spin-spin interaction is obtained from the coupling of nuclear magnetic moments to a virtual quantized magnetic field. The energy-dependent operators obtained reduce to usual classical-field expressions at suitable limits

Spin at Lausanne

International Nuclear Information System (INIS)

Anon.

1980-01-01

From 25 September to 1 October, some 150 spin enthusiasts gathered in Lausanne for the 1980 International Symposium on High Energy Physics with Polarized Beams and Polarized Targets. The programme was densely packed, covering physics interests with spin as well as the accelerator and target techniques which make spin physics possible

Unpolarised and spin-change collisions between He/sup +/ and H at low energies

Energy Technology Data Exchange (ETDEWEB)

Falcon, C; Opradolce, L [Instituto de Astronomia y Fisica del Espacio, Buenos Aires (Argentina); Piacentini, R D

1978-09-14

He/sup +/-H collisions are studied for energies lower than the electron excitation threshold. Unpolarised cross sections having resonances and values greater than 4000 a/sup 2//sub 0/ and spin-change cross sections showing high structures are obtained. Comparisons with the corresponding H-H collision cross sections are displayed. The sensitivity of the cross sections to the potential energy curves is discussed.

Innovation capabilities and challenges for energy smartdevelopment in medium sized European cities

NARCIS (Netherlands)

Lindhult, Erik; Campillo, J.; Dahlquist, E.; Read, S.A.

2016-01-01

Transition towards becoming Energy smart city integrating different areas of energy production, distribution and use in a community requires a spectrum of capabilities. The paper reports on findings from the EU planning project PLEEC, involving six medium sized European cities. The purpose of the

Spin Drag and Spin-Charge Separation in Cold Fermi Gases

International Nuclear Information System (INIS)

Polini, Marco; Vignale, Giovanni

2007-01-01

Low-energy spin and charge excitations of one-dimensional interacting fermions are completely decoupled and propagate with different velocities. These modes, however, can decay due to several possible mechanisms. In this Letter we expose a new facet of spin-charge separation: not only the speeds but also the damping rates of spin and charge excitations are different. While the propagation of long-wavelength charge excitations is essentially ballistic, spin propagation is intrinsically damped and diffusive. We suggest that cold Fermi gases trapped inside a tight atomic waveguide offer the opportunity to measure the spin-drag relaxation rate that controls the broadening of a spin packet

The Nuclear Spin Nanomagnet

OpenAIRE

Korenev, V. L.

2007-01-01

Linearly polarized light tuned slightly below the optical transition of the negatively charged exciton (trion) in a single quantum dot causes the spontaneous nuclear spin polarization (self-polarization) at a level close to 100%. The effective magnetic field of spin-polarized nuclei brings the optical transition energy into resonance with photon energy. The resonantly enhanced Overhauser effect sustains the stability of the nuclear self-polarization even in the absence of spin polarization of...

Spin and energy evolution equations for a wide class of extended bodies

International Nuclear Information System (INIS)

Racine, Etienne

2006-01-01

We give a surface integral derivation of the leading-order evolution equations for the spin and energy of a relativistic body interacting with other bodies in the post-Newtonian expansion scheme. The bodies can be arbitrarily shaped and can be strongly self-gravitating. The effects of all mass and current multipoles are taken into account. As part of the computation one of the 2PN potentials parametrizing the metric is obtained. The formulae obtained here for spin and energy evolution coincide with those obtained by Damour, Soffel and Xu for the case of weakly self-gravitating bodies. By combining an Einstein-Infeld-Hoffman-type surface integral approach with multipolar expansions we extend the domain of validity of these evolution equations to a wide class of strongly self-gravitating bodies. This paper completes in a self-contained way a previous work by Racine and Flanagan on translational equations of motion for compact objects

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...... constants of tellurophene and divinyl telluride were calculated at the SOPPA and DFT levels in a good agreement with experiment. A new full-electron basis set av3z-J for tellurium derived from the "relativistic" Dyall's basis set, dyall.av3z, and specifically optimized for the correlated calculations...... 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...

On the properties of nuclear matter with an excess of neutrons, spin-up neutrons and spin-up protons using effective nucleon-nucleon potential

International Nuclear Information System (INIS)

Hassan, M.Y.; Ramadan, S.

1978-01-01

The binding energy of nuclear matter with an excess of neutrons, with spin-up neutrons and spin-up protons (characterized by the corresponding parameters αsub(tau)=(N-Z)/A, αsub(n)=(N(up)-N(down))/A, and αsub(p)=(Z(up)-Z(down))/A) contains three symmetry energies: the isospin symmetry energy epsilon sub(tau), the spin symmetry energy epsilon sub(sigma) and the spin-isospin symmetry energy epsilon sub(sigma tau). These energies are calculated using velocity-dependent effective potential of s-wave interaction, which was developed by Dzhibuti and Mamasakhlisov. The spin, isospin and spin-isospin dependent parts of the single-particle potential in nuclear matter are also calculated using the same effective nucleon-nucleon potentials. The spin-spin part of the optical model potential is estimated. (author)

Summary of the 8th international symposium on high energy spin physics

International Nuclear Information System (INIS)

Bunce, G.

1988-01-01

The series of conferences on high energy spin physics dates back to Argonne, 1974, and the first use of the polarized proton beam at the ZGS. This conference is unique in that it is concerned both with the technology of spin and with particle physics: particle physicists need to know what experiments might be possible and target/beam/source physicists want to know what their work will lead to, and get new ideas. In many cases, and I believe that this is central to the success of spin physics and of this conference series, these are the same people. This summary will have three basic parts: where we are now relative to Argonne in 1974; a discussion of new experiments and theory---there were many new and intriguing results presented here; and new ideas for polarized sources, beams, and targets which point toward an exciting future program of particle physics. 13 refs., 2 figs., 4 tabs

Achieving 99.9% proton spin-flip efficiency at higher energy with a small rf dipole

CERN Document Server

Leonova, M A; Gebel, R; Hinterberger, F; Krisch, A D; Lehrach, A; Lorentz, B; Maier, R; Morozov, V S; Prasuhn, D; Raymond, R S; Schnase, A; Stockhorst, H; Ulbrich, K; Wong, V K; 10.1103/PhysRevLett.93.224801

2004-01-01

We recently used a new ferrite rf dipole to study spin flipping of a 2.1 GeV/c vertically polarized proton beam stored in the COSY Cooler Synchrotron in Julich, Germany. We swept the rf dipole's frequency through an rf-induced spin resonance to flip the beam's polarization direction. After determining the resonance's frequency, we varied the frequency range, frequency ramp time, and number of flips. At the rf dipole's maximum strength and optimum frequency range and ramp time, we measured a spin-flip efficiency of 99.92+or-0.04%. This result, along with a similar 0.49 GeV/c IUCF result, indicates that, due to the Lorentz invariance of an rf dipole's transverse integral Bdl and the weak energy dependence of its spin-resonance strength, an only 35% stronger rf dipole should allow efficient spin flipping in the 100 GeV BNL RHIC Collider or even the 7 TeV CERN Large Hadron Collider.

Spin manipulation and relaxation in spin-orbit qubits

Science.gov (United States)

Borhani, Massoud; Hu, Xuedong

2012-03-01

We derive a generalized form of the electric dipole spin resonance (EDSR) Hamiltonian in the presence of the spin-orbit interaction for single spins in an elliptic quantum dot (QD) subject to an arbitrary (in both direction and magnitude) applied magnetic field. We predict a nonlinear behavior of the Rabi frequency as a function of the magnetic field for sufficiently large Zeeman energies, and present a microscopic expression for the anisotropic electron g tensor. Similarly, an EDSR Hamiltonian is devised for two spins confined in a double quantum dot (DQD), where coherent Rabi oscillations between the singlet and triplet states are induced by jittering the inter-dot distance at the resonance frequency. Finally, we calculate two-electron-spin relaxation rates due to phonon emission, for both in-plane and perpendicular magnetic fields. Our results have immediate applications to current EDSR experiments on nanowire QDs, g-factor optimization of confined carriers, and spin decay measurements in DQD spin-orbit qubits.

Orbital rotation without orbital angular momentum: mechanical action of the spin part of the internal energy flow in light beams

DEFF Research Database (Denmark)

Angelsky, O. V.; Bekshaev, A. Ya; Maksimyak, P. P.

2012-01-01

flow upon tight focusing of the beam, usually applied for energy flow detection by means of the mechanical action upon probe particles. We propose a two-beam interference technique that results in an appreciable level of spin flow in moderately focused beams and detection of the orbital motion of probe...... particles within a field where the transverse energy circulation is associated exclusively with the spin flow. This result can be treated as the first demonstration of mechanical action of the spin flow of a light field....

Spin dynamics in electron synchrotrons

International Nuclear Information System (INIS)

Schmidt, Jan Felix

2017-01-01

Providing spin polarized particle beams with circular accelerators requires the consideration of depolarizing resonances which may significantly reduce the desired degree of polarization at specific beam energies. The corresponding spin dynamical effects are typically analyzed with numerical methods. In case of electron beams the influence of the emission of synchrotron radiation has to be taken into account. On short timescales, as in synchrotrons with a fast energy ramp or in damping rings, spin dynamics are investigated with spin tracking algorithms. This thesis presents the spin tracking code Polematrix as a versatile tool to study the impact of synchrotron radiation on spin dynamics. Spin tracking simulations have been performed based on the well established particle tracking code Elegant. The numerical studies demonstrate effects which are responsible for beam depolarization: Synchrotron side bands of depolarizing resonances and decoherence of spin precession. Polematrix can be utilized for any electron accelerator with minimal effort as it imports lattice files from the tracking programs MAD-X or Elegant. Polematrix has been published as open source software. Currently, the Electron Stretcher Accelerator ELSA at Bonn University is the only electron synchrotron worldwide providing a polarized beam. Integer and intrinsic depolarizing resonances are compensated with dedicated countermeasures during the fast energy ramp. Polarization measurements from ELSA demonstrate the particular spin dynamics of electrons and confirm the results of the spin tracking code Polematrix.

Spin 1990

Energy Technology Data Exchange (ETDEWEB)

Anton, Gisela

1990-12-15

The idea of the intrinsic angular momentum, or 'spin', of a particle has played an essential part in fundamental physics for more than 60 years, and its continuing importance was underlined at the 9th International Symposium on High Energy Spin Physics, held in September in Bonn.

Ground state properties of a spin chain within Heisenberg model with a single lacking spin site

International Nuclear Information System (INIS)

Mebrouki, M.

2011-01-01

The ground state and first excited state energies of an antiferromagnetic spin-1/2 chain with and without a single lacking spin site are computed using exact diagonalization method, within the Heisenberg model. In order to keep both parts of a spin chain with a lacking site connected, next nearest neighbors interactions are then introduced. Also, the Density Matrix Renormalization Group (DMRG) method is used, to investigate ground state energies of large system sizes; which permits us to inquire about the effect of large system sizes on energies. Other quantum quantities such as fidelity and correlation functions are also studied and compared in both cases. - Research highlights: → In this paper we compute ground state and first excited state energies of a spin chain with and without a lacking spin site. The next nearest neighbors are introduced with the antiferromagnetic Heisenberg spin-half. → Exact diagonalization is used for small systems, where DMRG method is used to compute energies for large systems. Other quantities like quantum fidelity and correlation are also computed. → Results are presented in figures with comments. → E 0 /N is computed in a function of N for several values of J 2 and for both systems. First excited energies are also investigated.

A medium energy neutron deep penetration experiment

International Nuclear Information System (INIS)

Amian, W.; Cloth, P.; Druecke, V.; Filges, D.; Paul, N.; Schaal, H.

1986-11-01

A deep penetration experiment conducted at the Los Alamos WNR facility's Spallation Neutron Target is compared with calculations using intra-nuclear-cascade and S N -transport codes installed at KFA-IRE. In the experiment medium energy reactions induced by neutrons between 15 MeV and about 150 MeV inside a quasi infinite slab of iron have been measured using copper foil monitors. Details of the experimental procedure and the theoretical methods are described. A comparison of absolute reaction rates for both experimentally and theoretically derived reactions is given. The present knowledge of the corresponding monitor reaction cross sections is discussed. (orig.)

Medium energy elementary particle physics

International Nuclear Information System (INIS)

1991-01-01

This report discusses the following topics: muon beam development at LAMPF; muon physics; a new precision measurement of the muon g-2 value; measurement of the spin-dependent structure functions of the neutron and proton; and meson factories

Spin-Wave Diode

Directory of Open Access Journals (Sweden)

Jin Lan (兰金

2015-12-01

Full Text Available A diode, a device allowing unidirectional signal transmission, is a fundamental element of logic structures, and it lies at the heart of modern information systems. The spin wave or magnon, representing a collective quasiparticle excitation of the magnetic order in magnetic materials, is a promising candidate for an information carrier for the next-generation energy-saving technologies. Here, we propose a scalable and reprogrammable pure spin-wave logic hardware architecture using domain walls and surface anisotropy stripes as waveguides on a single magnetic wafer. We demonstrate theoretically the design principle of the simplest logic component, a spin-wave diode, utilizing the chiral bound states in a magnetic domain wall with a Dzyaloshinskii-Moriya interaction, and confirm its performance through micromagnetic simulations. Our findings open a new vista for realizing different types of pure spin-wave logic components and finally achieving an energy-efficient and hardware-reprogrammable spin-wave computer.

Spin polarized deuterium

International Nuclear Information System (INIS)

Glyde, H.R.; Hernadi, S.I.

1986-01-01

Several ground state properties of (electron) spin-polarized deuterium (D) such as the energy, single quasiparticle energies and lifetimes, Landau parameters and sound velocities are evaluated. The calculations begin with the Kolos-Wolneiwicz potential and use the Galitskii-FeynmanHartree-Fock (GFHF) approximation. The deuteron nucleas has spin I = 1, and spin states I/sub z/ = 1,0,-1. We explore D 1 , D 2 and D 3 in which, respectively, one spin state only is populated, two states are equally populated, and three states are equally populated. We find the GFHF describes D 1 well, but D 2 and D 3 less well. The Landau parameters, F/sub L/, are small compared to liquid 3 He and very small for doubly polarized D 1 (i.e. the F/sub L/ decrease with nuclear polarization)

Spin 1990

International Nuclear Information System (INIS)

Anton, Gisela

1990-01-01

The idea of the intrinsic angular momentum, or 'spin', of a particle has played an essential part in fundamental physics for more than 60 years, and its continuing importance was underlined at the 9th International Symposium on High Energy Spin Physics, held in September in Bonn.

Ray trajectories for a spinning cosmic string and a manifestation of self-cloaking

International Nuclear Information System (INIS)

Anderson, Tom H.; Mackay, Tom G.; Lakhtakia, Akhlesh

2010-01-01

A study of ray trajectories was undertaken for the Tamm medium which represents the spacetime of a zero-tension cosmic spinning string, under the geometric-optics approximation. Our numerical studies revealed that: (i) rays never cross the string's boundary; (ii) the Tamm medium supports evanescent waves in regions of phase space that correspond to those regions of the string's spacetime which could support closed timelike curves; and (iii) a spinning string can be slightly visible while a non-spinning string is almost perfectly invisible.

Spin-isotropic continuum of spin excitations in antiferromagnetically ordered Fe1.07Te

Science.gov (United States)

Song, Yu; Lu, Xingye; Regnault, L.-P.; Su, Yixi; Lai, Hsin-Hua; Hu, Wen-Jun; Si, Qimiao; Dai, Pengcheng

2018-02-01

Unconventional superconductivity typically emerges in the presence of quasidegenerate ground states, and the associated intense fluctuations are likely responsible for generating the superconducting state. Here we use polarized neutron scattering to study the spin space anisotropy of spin excitations in Fe1.07Te exhibiting bicollinear antiferromagnetic (AF) order, the parent compound of FeTe1 -xSex superconductors. We confirm that the low-energy spin excitations are transverse spin waves, consistent with a local-moment origin of the bicollinear AF order. While the ordered moments lie in the a b plane in Fe1.07Te , it takes less energy for them to fluctuate out of plane, similar to BaFe2As2 and NaFeAs. At energies above E ≳20 meV, we find magnetic scattering to be dominated by an isotropic continuum that persists up to at least 50 meV. Although the isotropic spin excitations cannot be ascribed to spin waves from a long-range-ordered local-moment antiferromagnet, the continuum can result from the bicollinear magnetic order ground state of Fe1.07Te being quasidegenerate with plaquette magnetic order.

Positronium spin conversion during collisions with Xe and its application for measuring the kinetic energy

International Nuclear Information System (INIS)

Shibuya, Kengo; Kawamura, Yoshihiro; Saito, Haruo

2015-01-01

Positronium(Ps) can undergo ortho-para spin conversion reaction during Ps-Xecollisions due to spin-orbit interaction. We have investigated energy dependence of this reaction rate and found it is nearly proportional to T 2.1 , where T is the temperature (300-623 K), while the pick-off annihilation rate is proportional to T. The strong temperature dependence of the former annihilation rate is attributed to a nature of p-wave scattering because this reaction is forbidden in s-wave scattering. In addition, a new method for measuring Ps kinetic energy has been developed with a high resolution and a high sensitivity by utilizing the strong temperature dependence as a 'thermometer.' Analyzingthe obtained time evolution of Ps kinetic energy, we have determined the momentum transfer cross section during Ps-Xecollisions at a very low energy (40-60 meV) to be 12(2)×10 −16 cm 2 . (paper)

Positronium-alkali atom scattering at medium energies

International Nuclear Information System (INIS)

Chakraborty, Ajoy; Basu, Arindam; Sarkar, Nirmal K; Sinha, Prabal K

2004-01-01

We investigate the scattering of orthopositronium (o-Ps) atom off different atomic alkali targets (Na to Cs) at low and medium energies (up to 120 eV). Projectile-elastic and target-elastic close-coupling models have been employed to investigate the systems in addition to the static-exchange model. Elastic, excitation and total cross sections have been reported for all four systems. The magnitude of the alkali excitation cross section increases with increasing atomic number of the target atom while the position of the peak value shifts towards lower incident energies. The magnitudes of the Ps excitation and ionization cross sections increase steadily with atomic number with no change in the peak position. The reported results show regular behaviour with increasing atomic number of the target atom. Scattering parameters for the Ps-Rb and Ps-Cs systems are being reported for the first time

Probability of spin flipping of proton with energy 6.9 MeV at inelastic scattering with sup(54,56)Fe nuclei

International Nuclear Information System (INIS)

Prokopenko, V.S.; Sklyarenko, V.; Chernievskij, V.K.; Shustov, A.V.

1980-01-01

Spin-orbital effects of inelastic scattering of protons by nuclei with mean atomic weight are investigated along with the mechanisms of the reaction course by measuring proton spin flip. The experiment consists in measuring proton-gamma coincidences in mutually perpendicular planes by the technique of quick-slow coincidences. The excitation function of the 56 Fe(P,P 1 ) reaction is measured in the 3.5-6.2 MeV energy range. Angular dependences of probability of proton spin flip (a level of 2 + , 0.847 MeV) are measured at energies of incident protons of 4.96; 5.58 and 5.88 MeV. Measurements of probabilities of proton spin flipping at inelastic scattering by sup(54,56)Fe nuclei are performed in the process of studying spin-orbital effects and mechanisms of the reaction course. A conclusion is made that the inelastic scattering process in the energy range under investigation is mainly realized by two equivalent mechanisms: direct interaction and formation of a compound nucleus. Angular dependences for 54 Fe and 56 Fe noticeably differ in the values of probability of spin flip in the angular range of 50-150 deg

Injection system of teh SSC Medium Energy Booster

International Nuclear Information System (INIS)

Mao, N.; Gerig, R.; McGill, J.; Brown, K.

1994-04-01

The Medium Energy Booster (MEB) is the third of the SSCL accelerators and the largest of the resistive magnet synchrotrons. It accelerates protons from an injection momentum of 12 GeV/c to a top momentum of 200 GeV/c. A beam injection system has been designed to inject the beam transferred from the Low Energy Booster onto the MEB closed orbit in the MEB injection insertion region. The beam is injected via a vertical bending Lambertson septum magnet and a horizontal kicker with appropriate matching and very little beam loss and emittance dilution. The beam optics of the injection system is described in this paper. The required parameters of the Lambertson septum magnet and the injection kicker are given

Energy spectra in $p$-shell $\\Lambda$ hypernuclei and $^{19}_{\\Lambda}\\textrm{F}$ and spin-dependent $\\Lambda N$ interactions

OpenAIRE

Kanada-En'yo, Yoshiko; Isaka, Masahiro; Motoba, Toshio

2018-01-01

Energy spectra of $0s$-orbit $\\Lambda$ states in $p$-shell $\\Lambda$ hypernuclei ($^{A}_\\Lambda Z$) and those in $^{19}_{\\Lambda}\\textrm{F}$ are studied with the microscopic cluster model and antisymmetrized molecular dynamics using the $G$-matrix effective $\\Lambda N$ ($\\Lambda NG$) interactions. Spin-dependent terms of the ESC08a version of the $\\Lambda NG$ interactions are tested and phenomenologically tuned to reproduce observed energy spectra in $p$-shell $^{A}_\\Lambda Z$. Spin-dependent...

Spin symposium

Energy Technology Data Exchange (ETDEWEB)

Anon.

1989-01-15

The recent 8th International Symposium on High Energy Spin Physics at the University of Minnesota in Minneapolis, Minnesota, opened with a bang when L. Pondrom (Wisconsin), donning a hard hat borrowed from construction workers, ventured that 'spin, the notorious inessential complication of hadronic physics, is finally telling us what real QCD (quantum chromodynamics, the field theory of quarks and gluons) looks like.' He was referring to an animated discussion on the meaning of the recent spin oriented (polarized) scattering results from the European Muon Collaboration (EMC) at CERN and reported at the Symposium by R. Garnet (Liverpool) and P. Schuler (Yale) which show that the proton spin is not simply a reflection of the spins of its constituent quarks.

Angular momentum of phonons and its application to single-spin relaxation

Science.gov (United States)

Nakane, Jotaro J.; Kohno, Hiroshi

2018-05-01

We reexamine the relaxation process of a single spin embedded in an elastic medium, a problem studied recently by Garanin and Chudnovsky (GC) [Phys. Rev. B 92, 024421 (2015), 10.1103/PhysRevB.92.024421] from the viewpoint of angular-momentum transfer. Using Noether's theorem, we identify two distinct angular momenta of the medium, one Newtonian discussed by GC and the other field-theoretical, both of which consist of an orbital part and a spin part. For both angular momenta, we found that the orbital part is as essential as the spin part in the relaxation process. In particular, the angular-momentum transfer from the (real) spin to the Newtonian orbital part may be considered as an incipient rotation that leads to the Einstein-de Haas effect.

Collisional Penrose process with spinning particles

Science.gov (United States)

Mukherjee, Sajal

2018-03-01

In this article, we have investigated collisional Penrose process (CPP) using spinning particles in a Kerr spacetime. Recent studies have shown that the collision between two spinning particles can produce a significantly high energy in the center of mass frame. Here, we explicitly compute the energy extraction and efficiency as measured by an observer at infinity. We consider the colliding particles as well as the escaping particles may contain spins. It has been shown that the energy extraction is larger than the non-spinning case and also their possibility to escape to infinity is wider than the geodesics.

Development of the Advanced Energetic Pair Telescope (AdEPT) for Medium-Energy Gamma-Ray Astronomy

Science.gov (United States)

Hunter, Stanley D.; Bloser, Peter F.; Dion, Michael P.; McConnell, Mark L.; deNolfo, Georgia A.; Son, Seunghee; Ryan, James M.; Stecker, Floyd W.

2011-01-01

Progress in high-energy gamma-ray science has been dramatic since the launch of INTEGRAL, AGILE and FERMI. These instruments, however, are not optimized for observations in the medium-energy (approx.0.3< E(sub gamma)< approx.200 MeV) regime where many astrophysical objects exhibit unique, transitory behavior, such as spectral breaks, bursts, and flares. We outline some of the major science goals of a medium-energy mission. These science goals are best achieved with a combination of two telescopes, a Compton telescope and a pair telescope, optimized to provide significant improvements in angular resolution and sensitivity. In this paper we describe the design of the Advanced Energetic Pair Telescope (AdEPT) based on the Three-Dimensional Track Imager (3-DTI) detector. This technology achieves excellent, medium-energy sensitivity, angular resolution near the kinematic limit, and gamma-ray polarization sensitivity, by high resolution 3-D electron tracking. We describe the performance of a 30x30x30 cm3 prototype of the AdEPT instrument.

Science Requirements and Conceptual Design for a Polarized Medium Energy Electron-Ion Collider at Jlab

Energy Technology Data Exchange (ETDEWEB)

Abeyratne, S; Ahmed, S; Barber, D; Bisognano, J; Bogacz, A; Castilla, A; Chevtsov, P; Corneliussen, S; Deconinck, W; Degtiarenko, P; Delayen, J; Derbenev, Ya; DeSilva, S; Douglas, D; Dudnikov, V; Ent, R; Erdelyi, B; Evtushenko, P; Fujii, Yu; Filatov, Yury; Gaskell, D; Geng, R; Guzey, V; Horn, T; Hutton, A; Hyde, C; Johnson, R; Kim, Y; Klein, F; Kondratenko, A; Kondratenko, M; Krafft, G; Li, R; Lin, F; Manikonda, S; Marhauser, F; McKeown, R; Morozov, V; Dadel-Turonski, P; Nissen, E; Ostroumov, P; Pivi, M; Pilat, F; Poelker, M; Prokudin, A; Rimmer, R; Satogata, T; Sayed, H; Spata, M; Sullivan, M; Tennant, C; Terzic, B; Tiefenback, M; Wang, M; Wang, S; Weiss, C; Yunn, B

2012-08-01

Researchers have envisioned an electron-ion collider with ion species up to heavy ions, high polarization of electrons and light ions, and a well-matched center-of-mass energy range as an ideal gluon microscope to explore new frontiers of nuclear science. In its most recent Long Range Plan, the Nuclear Science Advisory Committee (NSAC) of the US Department of Energy and the National Science Foundation endorsed such a collider in the form of a 'half-recommendation.' As a response to this science need, Jefferson Lab and its user community have been engaged in feasibility studies of a medium energy polarized electron-ion collider (MEIC), cost-effectively utilizing Jefferson Lab's already existing Continuous Electron Beam Accelerator Facility (CEBAF). In close collaboration, this community of nuclear physicists and accelerator scientists has rigorously explored the science case and design concept for this envisioned grand instrument of science. An electron-ion collider embodies the vision of reaching the next frontier in Quantum Chromodynamics - understanding the behavior of hadrons as complex bound states of quarks and gluons. Whereas the 12 GeV Upgrade of CEBAF will map the valence-quark components of the nucleon and nuclear wave functions in detail, an electron-ion collider will determine the largely unknown role sea quarks play and for the first time study the glue that binds all atomic nuclei. The MEIC will allow nuclear scientists to map the spin and spatial structure of quarks and gluons in nucleons, to discover the collective effects of gluons in nuclei, and to understand the emergence of hadrons from quarks and gluons. The proposed electron-ion collider at Jefferson Lab will collide a highly polarized electron beam originating from the CEBAF recirculating superconducting radiofrequency (SRF) linear accelerator (linac) with highly polarized light-ion beams or unpolarized light- to heavy-ion beams from a new ion accelerator and storage complex. Since the very

Science Requirements and Conceptual Design for a Polarized Medium Energy Electron-Ion Collider at Jlab

International Nuclear Information System (INIS)

Abeyratne, S.; Accardi, A.; Ahmed, S.; Barber, D.; Bisognano, J.; Bogacz, A.; Castilla, A.; Chevtsov, P.; Corneliussen, S.; Deconinck, W.; Degtiarenko, P.; Delayen, J.; Derbenev, Ya.; DeSilva, S.; Douglas, D.; Dudnikov, V.; Ent, R.; Erdelyi, B.; Evtushenko, P.; Fujii, Yu; Filatov, Yury; Gaskell, D.; Geng, R.; Guzey, V.; Horn, T.; Hutton, A.; Hyde, C.; Johnson, R.; Kim, Y.; Klein, F.; Kondratenko, A.; Kondratenko, M.; Krafft, G.; Li, R.; Lin, F.; Manikonda, S.; Marhauser, F.; McKeown, R.; Morozov, V.; Dadel-Turonski, P.; Nissen, E.; Ostroumov, P.; Pivi, M.; Pilat, F.; Poelker, M.; Prokudin, A.; Rimmer, R.; Satogata, T.; Sayed, H.; Spata, M.; Sullivan, M.; Tennant, C.; Terzic, B.; Tiefenback, M.; Wang, H.; Wang, S.; Weiss, C.; Yunn, B.; Zhang, Y.

2012-01-01

Researchers have envisioned an electron-ion collider with ion species up to heavy ions, high polarization of electrons and light ions, and a well-matched center-of-mass energy range as an ideal gluon microscope to explore new frontiers of nuclear science. In its most recent Long Range Plan, the Nuclear Science Advisory Committee (NSAC) of the US Department of Energy and the National Science Foundation endorsed such a collider in the form of a 'half-recommendation.' As a response to this science need, Jefferson Lab and its user community have been engaged in feasibility studies of a medium energy polarized electron-ion collider (MEIC), cost-effectively utilizing Jefferson Lab's already existing Continuous Electron Beam Accelerator Facility (CEBAF). In close collaboration, this community of nuclear physicists and accelerator scientists has rigorously explored the science case and design concept for this envisioned grand instrument of science. An electron-ion collider embodies the vision of reaching the next frontier in Quantum Chromodynamics - understanding the behavior of hadrons as complex bound states of quarks and gluons. Whereas the 12 GeV Upgrade of CEBAF will map the valence-quark components of the nucleon and nuclear wave functions in detail, an electron-ion collider will determine the largely unknown role sea quarks play and for the first time study the glue that binds all atomic nuclei. The MEIC will allow nuclear scientists to map the spin and spatial structure of quarks and gluons in nucleons, to discover the collective effects of gluons in nuclei, and to understand the emergence of hadrons from quarks and gluons. The proposed electron-ion collider at Jefferson Lab will collide a highly polarized electron beam originating from the CEBAF recirculating superconducting radiofrequency (SRF) linear accelerator (linac) with highly polarized light-ion beams or unpolarized light- to heavy-ion beams from a new ion accelerator and storage complex. Since the very

Abrupt relaxation in high-spin molecules

International Nuclear Information System (INIS)

Chang, C.-R.; Cheng, T.C.

2000-01-01

Mean-field model suggests that the rate of resonant quantum tunneling in high-spin molecules is not only field-dependent but also time-dependent. The relaxation-assisted resonant tunneling in high-spin molecules produces an abrupt magnetization change during relaxation. When the applied field is very close to the resonant field, a time-dependent interaction field gradually shifts the energies of different collective spin states, and magnetization tunneling is observed as two energies of the spin states coincide

Study of transitional Erbium nuclei (N=86) at very high spin. Highlight of dipolar transitions and medium livetimes in the continuum

International Nuclear Information System (INIS)

Bogaert, G.

1984-01-01

Average lifetimes and multipolarities of unresolved transitions deexciting very high spin states of the light Rare Earth nuclei (N approximately 86) have been determined by a measure of Doppler shift attenuation and their anisotropy. The spin selection is provided by the total energy spectrometer technique; great care was taken of the existence of many long lived isomeric states in the studied nuclei. The N approximately 86 nuclei have been formed in the 84 Kr(340 MeV) + 74 Ge → 158 Er* reactions using the 84 Kr beam of the Orsay ALICE facilities and targets of 74 Ge built at the PARIS Isotope separator of the CSNSM. NaI γ spectra have been thoroughly cleared of the discrete lines contribution through a carefull subtraction procedure synthetising NaI spectra from the Ge ones. At very high spin the continuum γ rays feed two well separated bumps with Esub(γ) approximately .65 MeV and Esub(γ) approximately 1.3 MeV. The 1.3 MeV transitions appear at I > 30 h and their energy does not vary with the increasing spin like expected in the rotational case of the well deformed nuclei; they are strongly collectively enhanced with B(E2) > 130 W.u. Below 1 MeV the anisotropy of transitions is R approximately 0.7, indicating their stretched dipole nature. Recent calculations of nuclear shape deformation (following Strutinsky shell correction method) reproduce the two bumps shape of the experimental spectra and the origin of the excitation is explained in terms of nuclear vibration (γ-vibration, wobbling motion) [fr

Intercomparison of medium-energy neutron attenuation in iron and concrete

International Nuclear Information System (INIS)

Hirayama, H.

1999-01-01

Neutron attenuation of medium energy below 1 GeV has not been well understood until now. It is desired to obtain common agreements concerning the behaviours of neutrons inside various materials. This is necessary in order to agree on definitions of the attenuation length, which is very important for shielding calculations involving high energy accelerators. As one attempt, it was proposed by Japanese attendants of SATIF-2 to compare the attenuation of medium-energy neutrons inside iron and concrete shields between various computer codes and data, and was cited as a suitable action for SATIF. The first results from three groups were presented at SATIF-3. It has become clear that neutrons above 20 MeV are important for understanding the attenuation inside materials and that the geometry, planar or spherical, does not affect the results very much. Considering the CPU times required for Monte Carlo calculations and this result, revised problems to be calculated were prepared by the Japanese Working Group and sent to the participants of this action. The geometry is only plane, and calculations are required only for neutrons above 20 MeV. The secondary neutrons from high energy protons, which were calculated by H. Nakashima, are also included in the problem. The results from four groups were sent to the organizer at the end of August. This paper presents a comparison between groups concerning the attenuation length together with the neutron spectrum and the future themes which come from this intercomparison. (author)

Prospects for spin physics at RHIC

International Nuclear Information System (INIS)

Robinett, R.W.; Pennsylvania State Univ., University Park, PA

1995-06-01

The proposal to perform polarized proton-proton collisions at collider energies at RHIC is reviewed. After a brief reminder of the desirability of high energy spin physics measurements, we discuss the machine parameters and detector features which are taken to define a program of spin physics at RHIC. Some of the many physics processes which can provide information on polarized parton distributions and the spin-dependence of QCD and the electroweak model at RHIC energies are discussed

Quantum spin correction scheme based on spin-correlation functional for Kohn-Sham spin density functional theory

International Nuclear Information System (INIS)

Yamanaka, Shusuke; Takeda, Ryo; Nakata, Kazuto; Takada, Toshikazu; Shoji, Mitsuo; Kitagawa, Yasutaka; Yamaguchi, Kizashi

2007-01-01

We present a simple quantum correction scheme for ab initio Kohn-Sham spin density functional theory (KS-SDFT). This scheme is based on a mapping from ab initio results to a Heisenberg model Hamiltonian. The effective exchange integral is estimated by using energies and spin correlation functionals calculated by ab initio KS-SDFT. The quantum-corrected spin-correlation functional is open to be designed to cover specific quantum spin fluctuations. In this article, we present a simple correction for dinuclear compounds having multiple bonds. The computational results are discussed in relation to multireference (MR) DFT, by which we treat the quantum many-body effects explicitly

Spin diffusion in disordered organic semiconductors

Science.gov (United States)

Li, Ling; Gao, Nan; Lu, Nianduan; Liu, Ming; Bässler, Heinz

2015-12-01

An analytical theory for spin diffusion in disordered organic semiconductors is derived. It is based on percolation theory and variable range hopping in a disordered energy landscape with a Gaussian density of states. It describes universally the dependence of the spin diffusion on temperature, carrier density, material disorder, magnetic field, and electric field at the arbitrary magnitude of the Hubbard energy of charge pairs. It is found that, compared to the spin transport carried by carriers hopping, the spin exchange will hinder the spin diffusion process at low carrier density, even under the condition of a weak electric field. Importantly, under the influence of a bias voltage, anomalous spreading of the spin packet will lead to an abnormal temperature dependence of the spin diffusion coefficient and diffusion length. This explains the recent experimental data for spin diffusion length observed in Alq3.

Computer simulation program for medium-energy ion scattering and Rutherford backscattering spectrometry

Science.gov (United States)

Nishimura, Tomoaki

2016-03-01

A computer simulation program for ion scattering and its graphical user interface (MEISwin) has been developed. Using this program, researchers have analyzed medium-energy ion scattering and Rutherford backscattering spectrometry at Ritsumeikan University since 1998, and at Rutgers University since 2007. The main features of the program are as follows: (1) stopping power can be chosen from five datasets spanning several decades (from 1977 to 2011), (2) straggling can be chosen from two datasets, (3) spectral shape can be selected as Gaussian or exponentially modified Gaussian, (4) scattering cross sections can be selected as Coulomb or screened, (5) simulations adopt the resonant elastic scattering cross section of 16O(4He, 4He)16O, (6) pileup simulation for RBS spectra is supported, (7) natural and specific isotope abundances are supported, and (8) the charge fraction can be chosen from three patterns (fixed, energy-dependent, and ion fraction with charge-exchange parameters for medium-energy ion scattering). This study demonstrates and discusses the simulations and their results.

Förster resonance energy transfer between acridinediones and selected fluorophores—Medium dependence

Energy Technology Data Exchange (ETDEWEB)

Krishnaveni, R. [National Centre for Ultrafast Processes, University of Madras, Taramani Campus, Chennai-600113 (India); Ramamurthy, P., E-mail: prm60@hotmail.com [National Centre for Ultrafast Processes, University of Madras, Taramani Campus, Chennai-600113 (India)

2013-06-15

We report highly efficient Förster resonance energy transfer process between acridinedione dyes and basic fluorophores. FRET between free and β-cyclodextrin modified acridinediones as donors and fluorophoric dyes like safranine as acceptor were investigated in an alcoholic medium, polymer solution and a polymeric film. Efficiency of the processes were experimentally found by steady-state and time-resolved experiments for different donor and acceptor combinations. The associated spectral parameters viz., R{sup 0}, J(λ) were calculated, the Stern–Volmer relations based on fluorescence intensity and lifetime were constructed and the rates of energy transfer were calculated. The results indicated that the dominant mechanism responsible for the excitation energy transfer is that of resonance transfer due to long range dipole–dipole interaction and the process was found to be highly efficient when the medium was a constrained one as in the case of a polymeric film. A multifold enhancement in efficiency of energy transfer was also observed when the donor was a modified acridinedione when compared to a free acridinedione. The reason is attributed to the effective binding of the acceptor into the cavity of β-cyclodextrin. Highlights: ► FRET between acridinediones and fluorophoric acceptors were investigated. ► FRET analysis was carried out in methanol, a 5% PVA solution and in PVA matrix. ► FRET efficiency was maximum when the medium was PVA matrix. ► FRET efficiency was also more when β-CD modified ADR is used as the donor. ► Efficiency enhancement is due to the inclusion of acceptor into the cavity of β-CD.

On the properties of nuclear matter with an excess of neutrons, of spin-up neutrons and of spin-up protons using the Skyrme interaction

International Nuclear Information System (INIS)

Hassan, M.Y.M.; Ramadan, S.

1983-11-01

The binding energy of nuclear matter with an excess of neutrons, of spin-up neutrons, and of spin-up protons (characterized by the corresponding parameters, αsub(tau)=(N-Z/A), αsub(n)=(Nup-Ndown)/A, and αsub(rho)=(Zup-Zdown)/A), contains three symmetry energies: the isospin symmetry energy Esub(tau), the spin symmetry energy Esub(σ), and spin-isospin symmetry energy Esub(σtau). General expressions for Esub(σ), Esub(tau) and Esub(σtau) are given in the case of the Skyrme interaction. These values are compared with previous results obtained by Dabrowski and Haensel (DH) with Brueckner-Gammel-Thaler, the Hamada-Johnston, and the Reid soft core nucleon-nucleon potentials. The spin, isospin and spin-isospin dependent parts of the single-particle potential in nuclear matter are also calculated using the Skyrme interaction. The spin, isospin and spin-isospin incompressibility are calculated using the Skyrme interaction. The spin-spin part of the optical model potential is estimated. The results are compared with those of Dabrowski and Haensel (DH) and Hassan and Ramadan. (author)

Spin inelastic electron tunneling spectroscopy on local spin adsorbed on surface.

Science.gov (United States)

Fransson, J

2009-06-01

The recent experimental conductance measurements taken on magnetic impurities on metallic surfaces, using scanning tunneling microscopy technique and suggesting occurrence of inelastic scattering processes, are theoretically addressed. We argue that the observed conductance signatures are caused by transitions between the spin states that have opened due to, for example, exchange coupling between the local spins and the tunneling electrons, and are directly interpretable in terms of inelastic transitions energies. Feasible measurements using spin-polarized scanning tunneling microscopy that would enable new information about the excitation spectrum of the local spins are discussed.

Workshop on Hydrogen Storage and Generation for Medium-Power and -Energy Applications

National Research Council Canada - National Science Library

Matthews, Michael

1998-01-01

This report summarizes the Workshop on Hydrogen Storage and Generation Technologies for Medium-Power and -Energy Applications which was held on April 8-10, 1997 at the Radisson Hotel Orlando Airport in Orlando, Florida...

Spin-orbit torque induced magnetic vortex polarity reversal utilizing spin-Hall effect

Science.gov (United States)

Li, Cheng; Cai, Li; Liu, Baojun; Yang, Xiaokuo; Cui, Huanqing; Wang, Sen; Wei, Bo

2018-05-01

We propose an effective magnetic vortex polarity reversal scheme that makes use of spin-orbit torque introduced by spin-Hall effect in heavy-metal/ferromagnet multilayers structure, which can result in subnanosecond polarity reversal without endangering the structural stability. Micromagnetic simulations are performed to investigate the spin-Hall effect driven dynamics evolution of magnetic vortex. The mechanism of magnetic vortex polarity reversal is uncovered by a quantitative analysis of exchange energy density, magnetostatic energy density, and their total energy density. The simulation results indicate that the magnetic vortex polarity is reversed through the nucleation-annihilation process of topological vortex-antivortex pair. This scheme is an attractive option for ultra-fast magnetic vortex polarity reversal, which can be used as the guidelines for the choice of polarity reversal scheme in vortex-based random access memory.

Dresselhaus spin-orbit coupling induced spin-polarization and resonance-split in n-well semiconductor superlattices

International Nuclear Information System (INIS)

Ye Chengzhi; Xue Rui; Nie, Y.-H.; Liang, J.-Q.

2009-01-01

Using the transfer matrix method, we investigate the electron transmission over multiple-well semiconductor superlattices with Dresselhaus spin-orbit coupling in the potential-well regions. The superlattice structure enhances the effect of spin polarization in the transmission spectrum. The minibands of multiple-well superlattices for electrons with different spin can be completely separated at the low incident energy, leading to the 100% spin polarization in a broad energy windows, which may be an effective scheme for realizing spin filtering. Moreover, for the transmission over n-quantum-well, it is observed that the resonance peaks in the minibands split into n-folds or (n-1)-folds depending on the well-width and barrier-thickness, which is different from the case of tunneling through n-barrier structure

A stochastic security approach to energy and spinning reserve scheduling considering demand response program

International Nuclear Information System (INIS)

Partovi, Farzad; Nikzad, Mehdi; Mozafari, Babak; Ranjbar, Ali Mohamad

2011-01-01

In this paper a new algorithm for allocating energy and determining the optimum amount of network active power reserve capacity and the share of generating units and demand side contribution in providing reserve capacity requirements for day-ahead market is presented. In the proposed method, the optimum amount of reserve requirement is determined based on network security set by operator. In this regard, Expected Load Not Supplied (ELNS) is used to evaluate system security in each hour. The proposed method has been implemented over the IEEE 24-bus test system and the results are compared with a deterministic security approach, which considers certain and fixed amount of reserve capacity in each hour. This comparison is done from economic and technical points of view. The promising results show the effectiveness of the proposed model which is formulated as mixed integer linear programming (MILP) and solved by GAMS software. -- Highlights: → Determination of optimal spinning reserve capacity requirement in order to satisfy desired security level set by system operator based on stochastic approach. → Scheduling energy and spinning reserve markets simultaneously. → Comparing the stochastic approach with deterministic approach to determine the advantages and disadvantages of each. → Examine the effect of demand response participation in reserve market to provide spinning reserve.

SU (N ) spin-wave theory: Application to spin-orbital Mott insulators

Science.gov (United States)

Dong, Zhao-Yang; Wang, Wei; Li, Jian-Xin

2018-05-01

We present the application of the SU (N ) spin-wave theory to spin-orbital Mott insulators whose ground states exhibit magnetic orders. When taking both spin and orbital degrees of freedom into account rather than projecting Hilbert space onto the Kramers doublet, which is the lowest spin-orbital locked energy levels, the SU (N ) spin-wave theory should take the place of the SU (2 ) one due to the inevitable spin-orbital multipole exchange interactions. To implement the application, we introduce an efficient general local mean-field method, which involves all local fluctuations, and develop the SU (N ) linear spin-wave theory. Our approach is tested firstly by calculating the multipolar spin-wave spectra of the SU (4 ) antiferromagnetic model. Then, we apply it to spin-orbital Mott insulators. It is revealed that the Hund's coupling would influence the effectiveness of the isospin-1 /2 picture when the spin-orbital coupling is not large enough. We further carry out the SU (N ) spin-wave calculations of two materials, α -RuCl3 and Sr2IrO4 , and find that the magnonic and spin-orbital excitations are consistent with experiments.

A possible method to produce a polarized antiproton beam at intermediate energies

International Nuclear Information System (INIS)

Spinka, H.; Vaandering, E.W.; Hofmann, J.S.

1994-01-01

A feasible and conservative design for a medium energy polarized antiproton beam has been presented. The design requires an intense beam of unpolarized antiprotons (≥ 10 7 /sec) from a typical secondary beam line in order to achieve reasonable anti pp elastic scattering count rates. All three beam spin directions can be achieved. Methods were discussed to reverse the spin directions in modest times, and to change to a polarized proton beam if desired. It is expected that experiments with such a beam would have a profound effect on the understanding of the anti NN interaction at intermediate energies

Spin-isospin excitations induced by heavy ions at Saturne energies

International Nuclear Information System (INIS)

Hennino, T.

1989-01-01

Our program on the Spin-Isospin excitations started with the ( 3 He, 3 H) and ( 2 H, 2 He) reactions was extended with the heavy ion beams available at Saturne ( 12 C, 16 0, 20 Ne and 40 Ar) to study systematically the Δ excitation energy region. Projectile-ejectile dependences were measured. The Δ peak shift appears as a common feature in all charge exchange reactions. The first cross section calculations for the ( 12 C, 12 N) reaction are in good quantitative agreement with the data [fr

Energy losses (gains) of massive coloured particles in stochastic colour medium

International Nuclear Information System (INIS)

Leonidov, A.; Rossijskaya Akademiya Nauk, Moscow

1995-01-01

The propagation of massive coloured particles in stochastic background chromoelectric field is studied using the semiclassical equations of motion. Depending on the nature of the stochastic background we obtain the formulae for the energy losses of heavy coloured projectile in nonperturbative hadronic medium and for the energy gains in the stochastic field present, e.g., in the turbulent plasma. The result appears to be significantly dependent on the form of the correlation function of stochastic external field. (orig.)

Anomalous resonance-radiation energy-transfer rate in a scattering dispersive medium

International Nuclear Information System (INIS)

Shekhtman, V.L.

1992-01-01

This paper describes a generalization of the concept of group velocity as an energy-transfer rate in a dispersive medium with complex refractive index when the polaritons, which are energy carriers, undergo scattering, in contrast to the classical concept of the group velocity of free polaritons (i.e., without scattering in the medium). The concept of delay time from quantum multichannel-scattering, theory is used as the fundamental concept. Based on Maxwell's equations and the new mathematical Φ-function method, a consistent conceptual definition of group velocity in terms of the ratio of the coherent-energy flux density to the coherent-energy density is obtained for the first time, and a critical analysis of the earlier (Brillouin) understanding of energy-transfer rate is given in the light of radiation-trapping theory and the quantum theory of resonance scattering. The role of generalized group velocity is examined for the interpretation of the phenomenon of multiple resonance scattering, or radiation diffusion. The question of causality for the given problem is touched upon; a new relationship is obtained, called the microcausality condition, which limits the anomalous values of group velocity by way of the indeterminacy principle and the relativistic causality principle for macroscopic time intervals directly measurable in experiment, whereby attention is focused on the connection of the given microcausality condition and the well-known Wigner inequality for the time delay of spherical waves. 22 refs

Nuclear spin-isospin excitations from covariant quasiparticle-vibration coupling

Science.gov (United States)

Robin, Caroline; Litvinova, Elena

2016-09-01

Methods based on the relativistic Lagrangian of quantum hadrodynamics and nuclear field theory provide a consistent framework for the description of nuclear excitations, naturally connecting the high- and medium-energy scales of mesons to the low-energy domain of nucleonic collective motion. Applied in the neutral channel, this approach has been quite successful in describing the overall transition strength up to high excitation energies, as well as fine details of the low-lying distribution. Recently, this method has been extended to the description of spin-isospin excitations in open-shell nuclei. In the charge-exchange channel, the coupling between nucleons and collective vibrations generates a time-dependent proton-neutron effective interaction, in addition to the static pion and rho-meson exchange, and introduces complex configurations that induce fragmentation and spreading of the resonances. Such effects have a great impact on the quenching of the strength and on the computing of weak reaction rates that are needed for astrophysics modeling. Gamow-Teller transitions in medium-mass nuclei and associated beta-decay half-lives will be presented. Further developments aiming to include additional ground-state correlations will also be discussed. This work is supported by US-NSF Grants PHY-1404343 and PHY-1204486.

Description of inelastic nucleus-nucleus interactions at medium energy using dual parton model

International Nuclear Information System (INIS)

Polanski, A.; Shmakov, S.Yu.; Uzhinskij, V.V.

1989-01-01

It is shown that the dual parton model taking into account the processes of diffraction dissociation to the low mass states and finite energy corrections to the asymptotic Abramovski-Gribov-Kancheli cutting rules allows satisfactory description of existing experimental data on hadron-nucleus and nucleus-nucleus interactions at medium energy. (orig.)

Statistical calculation of complete events in medium-energy nuclear collisions

International Nuclear Information System (INIS)

Randrup, J.

1984-01-01

Several heavy-ion accelerators throughout the world are presently able to deliver beams of heavy nuclei with kinetic energies in the range from tens to hundreds of MeV per nucleon, the so-called medium or intermediate energy range. At such energies a large number of final channels are open, each consisting of many nuclear fragments. The disassembly of the collision system is expected to be a very complicated process and a detailed dynamical description is beyond their present capability. However, by virtue of the complexity of the process, statistical considerations may be useful. A statistical description of the disassembly yields the least biased expectations about the outcome of a collision process and provides a meaningful reference against which more specific dynamical models, as well as the data, can be discussed. This lecture presents the essential tools for formulating a statistical model for the nuclear disassembly process. The authors consider the quick disassembly (explosion) of a hot nuclear system, a so-called source, into multifragment final states, which complete according to their statistical weight. First some useful notation is introduced. Then the expressions for exclusive and inclusive distributions are given and the factorization of an exclusive distribution into inclusive ones is carried out. In turn, the grand canonical approximation for one-fragment inclusive distributions is introduced. Finally, it is outlined how to generate a statistical sample of complete final states. On this basis, a model for statistical simulation of complete events in medium-energy nuclear collisions has been developed

Spin polarisation with electron Bessel beams

Energy Technology Data Exchange (ETDEWEB)

Schattschneider, P., E-mail: schattschneider@ifp.tuwien.ac.at [Institut für Festkörperphysik, Technische Universität Wien, A-1040 Wien (Austria); USTEM, Technische Universität Wien, A-1040 Wien (Austria); Grillo, V. [CNR-Istituto Nanoscienze, Centro S3, Via G Campi 213/a, I-41125 Modena (Italy); CNR-IMEM, Parco delle Scienze 37a, I-43100 Parma (Italy); Aubry, D. [Centrale Supelec, MSSMast CNRS 8579, F-92295 Châtenay-Malabry (France)

2017-05-15

The theoretical possibility to use an electron microscope as a spin polarizer is studied. It turns out that a Bessel beam passing a standard magnetic objective lens is intrinsically spin polarized when post-selected on-axis. In the limit of infinitely small detectors, the spin polarisation tends to 100 %. Increasing the detector size, the polarisation decreases rapidly, dropping below 10{sup −4} for standard settings of medium voltage microscopes. For extremely low voltages, the Figure of Merit increases by two orders of magnitude, approaching that of existing Mott detectors. Our findings may lead to new desings of spin filters, an attractive option in view of its inherent combination with the electron microscope, especially at low voltage. - Highlights: • TEM round magnetic lenses can act as spin polarizers when a Bessel beam is sent through. • This is found on theoretical grounds and demonstrated numerically for a few cases. • The effect is small, but can reach a Figure of Merit similar to existing Mott detectors. • This opens the possibility to construct nanometer-sized spin filters or detectors.

A low-temperature derivation of spin-spin exchange in Kondo lattice model

International Nuclear Information System (INIS)

Feng Szeshiang; Mochena, Mogus

2005-01-01

Using Hubbard-Stratonovich transformation and drone-fermion representations for spin-12 and for spin-32, which is presented for the first time, we make a path-integral formulation of the Kondo lattice model. In the case of weak coupling and low temperature, the functional integral over conduction fermions can be approximated to the quadratic order and this gives the well-known RKKY interaction. In the case of strong coupling, the same quadratic approximation leads to an effective local spin-spin interaction linear in hopping energy t

A low-temperature derivation of spin-spin exchange in Kondo lattice model

Energy Technology Data Exchange (ETDEWEB)

Feng Szeshiang [Physics Department, Florida A and M University, Tallahassee, FL 32307 (United States)]. E-mail: shixiang.feng@famu.edu; Mochena, Mogus [Physics Department, Florida A and M University, Tallahassee, FL 32307 (United States)

2005-11-01

Using Hubbard-Stratonovich transformation and drone-fermion representations for spin-12 and for spin-32, which is presented for the first time, we make a path-integral formulation of the Kondo lattice model. In the case of weak coupling and low temperature, the functional integral over conduction fermions can be approximated to the quadratic order and this gives the well-known RKKY interaction. In the case of strong coupling, the same quadratic approximation leads to an effective local spin-spin interaction linear in hopping energy t.

Spin wave dynamics in Heisenberg ferromagnetic/antiferromagnetic single-walled nanotubes

Energy Technology Data Exchange (ETDEWEB)

Mi, Bin-Zhou, E-mail: mbzfjerry2008@126.com [Department of Basic Curriculum, North China Institute of Science and Technology, Beijing 101601 (China); Department of Physics, School of Mathematics and Physics, University of Science and Technology Beijing, Beijing 100083 (China)

2016-09-15

The spin wave dynamics, including the magnetization, spin wave dispersion relation, and energy level splitting, of Heisenberg ferromagnetic/antiferromagnetic single-walled nanotubes are systematically calculated by use of the double-time Green’s function method within the random phase approximation. The role of temperature, diameter of the tube, and wave vector on spin wave energy spectrum and energy level splitting are carefully analyzed. There are two categories of spin wave modes, which are quantized and degenerate, and the total number of independent magnon branches is dependent on diameter of the tube, caused by the physical symmetry of nanotubes. Moreover, the number of flat spin wave modes increases with diameter of the tube rising. The spin wave energy and the energy level splitting decrease with temperature rising, and become zero as temperature reaches the critical point. At any temperature, the energy level splitting varies with wave vector, and for a larger wave vector it is smaller. When pb=π, the boundary of first Brillouin zone, spin wave energies are degenerate, and the energy level splittings are zero.

An endohedral fullerene-based nuclear spin quantum computer

International Nuclear Information System (INIS)

Ju Chenyong; Suter, Dieter; Du Jiangfeng

2011-01-01

We propose a new scalable quantum computer architecture based on endohedral fullerene molecules. Qubits are encoded in the nuclear spins of the endohedral atoms, which posses even longer coherence times than the electron spins which are used as the qubits in previous proposals. To address the individual qubits, we use the hyperfine interaction, which distinguishes two modes (active and passive) of the nuclear spin. Two-qubit quantum gates are effectively implemented by employing the electronic dipolar interaction between adjacent molecules. The electron spins also assist in the qubit initialization and readout. Our architecture should be significantly easier to implement than earlier proposals for spin-based quantum computers, such as the concept of Kane [B.E. Kane, Nature 393 (1998) 133]. - Research highlights: → We propose an endohedral fullerene-based scalable quantum computer architecture. → Qubits are encoded on nuclear spins, while electron spins serve as auxiliaries. → Nuclear spins are individually addressed using the hyperfine interaction. → Two-qubit gates are implemented through the medium of electron spins.

Computer simulation program for medium-energy ion scattering and Rutherford backscattering spectrometry

Energy Technology Data Exchange (ETDEWEB)

Nishimura, Tomoaki, E-mail: t-nishi@hosei.ac.jp

2016-03-15

A computer simulation program for ion scattering and its graphical user interface (MEISwin) has been developed. Using this program, researchers have analyzed medium-energy ion scattering and Rutherford backscattering spectrometry at Ritsumeikan University since 1998, and at Rutgers University since 2007. The main features of the program are as follows: (1) stopping power can be chosen from five datasets spanning several decades (from 1977 to 2011), (2) straggling can be chosen from two datasets, (3) spectral shape can be selected as Gaussian or exponentially modified Gaussian, (4) scattering cross sections can be selected as Coulomb or screened, (5) simulations adopt the resonant elastic scattering cross section of {sup 16}O({sup 4}He, {sup 4}He){sup 16}O, (6) pileup simulation for RBS spectra is supported, (7) natural and specific isotope abundances are supported, and (8) the charge fraction can be chosen from three patterns (fixed, energy-dependent, and ion fraction with charge-exchange parameters for medium-energy ion scattering). This study demonstrates and discusses the simulations and their results.

Medium Energy Particle Physics - Muonium/RHIC - SPIN

International Nuclear Information System (INIS)

Hughes, V. W.

2003-01-01

This grant enabled research from 1991 to 2001 on muonium, the bound state of a positive muon and electron. The effort was led by Vernon Hughes, and involved almost 20 physicists from four U.S. and two international institutions. The experiment E1054 performed under the grant at the Clinton P. Anderson Meson Physics Facility at Los Alamos, was both a continuation and improvement on a series of experiments dating back to the discovery of muonium in 1960. High precision measurements of two Zeeman hyperfine transitions in the ground state of muonium were made, using microwave magnetic resonance spectroscopy and a line-narrowing technique. The experiment yielded the most precise values for the ground state hyperfine interval, Δv, to 12 ppb, and the ratio of muon to proton magnetic moments, μ μ /μ p to 120 ppb, representing a threefold (statistics limited) improvement over previous work. The mass of the muon, m μ , is also determined most precisely from this work. Comparison between theory and experiment for Δv constitutes the most precise test of bound-state QED, and also tests μe universality. Using the theoretical predictions for Δv, a value of the fine structure constant α was derived to 58 ppb. Finally, by searching for sidereal variations in the transition frequencies, limits were placed on the muon parameters of theoretical extensions of the standard model allowing CPT and Lorentz violation

Relativistic fluid dynamics with spin

Science.gov (United States)

Florkowski, Wojciech; Friman, Bengt; Jaiswal, Amaresh; Speranza, Enrico

2018-04-01

Using the conservation laws for charge, energy, momentum, and angular momentum, we derive hydrodynamic equations for the charge density, local temperature, and fluid velocity, as well as for the polarization tensor, starting from local equilibrium distribution functions for particles and antiparticles with spin 1/2. The resulting set of differential equations extends the standard picture of perfect-fluid hydrodynamics with a conserved entropy current in a minimal way. This framework can be used in space-time analyses of the evolution of spin and polarization in various physical systems including high-energy nuclear collisions. We demonstrate that a stationary vortex, which exhibits vorticity-spin alignment, corresponds to a special solution of the spin-hydrodynamical equations.

Medium energy measurements of n-n parameters: Progress in research, January 1, 1986-December 31, 1986

International Nuclear Information System (INIS)

Riley, P.J.

1987-01-01

A major part of the work has been and will continue to be associated with research done at the Nucleon Physics Laboratory (NPL) at the Los Alamos Meson Physics Facility (LAMPF). The aim of the experimental program is the determination of the nucleon-nucleon amplitudes at medium energy. The required data include both elastic and inelastic experiments, and in addition the measurement of polarization and polarization transfer parameters. We have been emphasizing single pion production measurements using polarized proton beams, and expect that our present data base will provide stringent tests of theoretical models. With the development of the LAMPF high intensity polarized proton source, we expect that a reasonably intense beam of medium energy polarized neutrons will become available, and are planning a series of experiments utilizing polarized neutrons to determine the importance of the I = 0 reaction amplitudes at medium energies

Spin 0 and spin 1/2 quantum relativistic particles in a constant gravitational field

International Nuclear Information System (INIS)

Khorrami, M.; Alimohammadi, M.; Shariati, A.

2003-01-01

The Klein-Gordon and Dirac equations in a semi-infinite lab (x>0), in the background metric ds 2 =u 2 (x)(-dt 2 +dx 2 )+dy 2 +dz 2 , are investigated. The resulting equations are studied for the special case u(x)=1+gx. It is shown that in the case of zero transverse-momentum, the square of the energy eigenvalues of the spin-1/2 particles are less than the squares of the corresponding eigenvalues of spin-0 particles with same masses, by an amount of mgℎc. Finally, for non-zero transverse-momentum, the energy eigenvalues corresponding to large quantum numbers are obtained and the results for spin-0 and spin-1/2 particles are compared to each other

Energies and damping rates of elementary excitations in spin-1 Bose-Einstein-condensed gases

International Nuclear Information System (INIS)

Szirmai, Gergely; Szepfalusy, Peter; Kis-Szabo, Krisztian

2003-01-01

The finite temperature Green's function technique is used to calculate the energies and damping rates of the elementary excitations of homogeneous, dilute, spin-1 Bose gases below the Bose-Einstein condensation temperature in both the density and spin channels. For this purpose a self-consistent dynamical Hartree-Fock model is formulated, which takes into account the direct and exchange processes on equal footing by summing up certain classes of Feynman diagrams. The model is shown to satisfy the Goldstone theorem and to exhibit the hybridization of one-particle and collective excitations correctly. The results are applied to gases of 23 Na and 87 Rb atoms

A program in medium-energy nuclear physics

International Nuclear Information System (INIS)

Berman, B.L.; Dhuga, K.S.

1992-01-01

This report reviews progress on our nuclear-physics program for the last year, and includes as well copies of our publications and other reports for that time period. The structure of this report follows that of our 1991 Renewal Proposal and Progress Report: Sec. II outlines our research activities aimed at future experiments at CEBAF, NIKHEF, and Bates; Sec. III gives results of our recent research activities at NIKHEF, LAMPF, and elsewhere; Sec. IV provides an update of our laboratory activities at GWU, including the acquisition of our new Nuclear Detector Laboratory at our new Virginia Campus; and Sec. V is a list of our publications, proposals, and other reports. copies of those on medium-energy nuclear physics are reproduced in the Appendix

Experimental medium energy physics: Annual progress report June 1987--May 1988

International Nuclear Information System (INIS)

1988-01-01

This report discusses progress in experimental medium energy physics at Carnegie Mellon University. Some of the topics covered are: search for the ξ(2230); hyperon-antihyperon production studies; relativistic proton-nucleus and heavy ion-nucleus collisions; H dibaryon physics; hypernuclear physics research; pion physics; H particle experiment design and development; and electron scattering

Summary: Symmetries and spin

International Nuclear Information System (INIS)

Haxton, W.C.

1988-01-01

I discuss a number of the themes of the Symmetries and Spin session of the 8th International Symposium on High Energy Spin Physics: parity nonconservation, CP/T nonconservation, and tests of charge symmetry and charge independence. 28 refs., 1 fig

Low-energy-state dynamics of entanglement for spin systems

International Nuclear Information System (INIS)

Jafari, R.

2010-01-01

We develop the ideas of the quantum renormalization group and quantum information by exploring the low-energy-state dynamics of entanglement resources of a system close to its quantum critical point. We demonstrate that low-energy-state dynamical quantities of one-dimensional magnetic systems can show a quantum phase transition point and show scaling behavior in the vicinity of the transition point. To present our idea, we study the evolution of two spin entanglements in the one-dimensional Ising model in the transverse field. The system is initialized as the so-called thermal ground state of the pure Ising model. We investigate the evolution of the generation of entanglement with increasing magnetic field. We obtain that the derivative of the time at which the entanglement reaches its maximum with respect to the transverse field diverges at the critical point and its scaling behaviors versus the size of the system are the same as the static ground-state entanglement of the system.

Material Targets for Scaling All-Spin Logic

Science.gov (United States)

Manipatruni, Sasikanth; Nikonov, Dmitri E.; Young, Ian A.

2016-01-01

All-spin-logic devices are promising candidates to augment and complement beyond-CMOS integrated circuit computing due to nonvolatility, ultralow operating voltages, higher logical efficiency, and high density integration. However, the path to reach lower energy-delay product performance compared to CMOS transistors currently is not clear. We show that scaling and engineering the nanoscale magnetic materials and interfaces is the key to realizing spin-logic devices that can surpass the energy-delay performance of CMOS transistors. With validated stochastic nanomagnetic and vector spin-transport numerical models, we derive the target material and interface properties for the nanomagnets and channels. We identify promising directions for material engineering and discovery focusing on the systematic scaling of magnetic anisotropy (Hk ) and saturation magnetization (Ms ), the use of perpendicular magnetic anisotropy, and the interface spin-mixing conductance of the ferromagnet-spin-channel interface (Gmix ). We provide systematic targets for scaling a spin-logic energy-delay product toward 2 aJ ns, comprehending the stochastic noise for nanomagnets.

Low energy spin dynamics of rare-earth orthoferrites YFeO3 and LaFeO3

Science.gov (United States)

Park, Kisoo; Sim, Hasung; Leiner, Jonathan; Yoshida, Yoshiyuki; Eisaki, Hiroshi; Yano, Shinichiro; Gardner, Jason; Park, Je-Geun

YFeO3 and LaFeO3\\ are members of the rare-earth orthoferrites (RFeO3) family with Pbnm space group. With the strong superexchange interaction between Fe3 + ions, both compounds exhibit the room temperature antiferromagnetic order (TN >600 K) with a slight spin canting. Here we report low-energy magnetic excitation of YFeO3 and LaFeO3 using inelastic neutron scattering measurements, showing evidence of magnon mode splitting and a spin anisotropy gap at the zone center. Spin wave calculations with the spin Hamiltonian including both Dzyaloshinsky-Moriya interaction and single-ion anisotropy accounts for the observed features well. Our results offer insight into the underlying physics of other RFeO3\\ with magnetic rare-earth ions or related Fe3+-based multiferroic perovskites such as BiFeO3. The work at the IBS CCES (South Korea) was supported by the research program of the Institute for Basic Science (IBS-R009-G1).

Experimental medium energy physics. Annual progress report, June 1985-May 1986

International Nuclear Information System (INIS)

1986-01-01

During the past year the CMU Medium Energy Physics Group has been involved in the running of three experiments. In addition, software and hardware for two new experiments scheduled to take place over the next few months have been developed. A new proposal, ''Search for a Strangeness -2 Dibaryon Using a 3 He Target,'' was submitted to the Brookhaven Program Advisory Committee and recently approved. In the spring of this year, studies of hypernuclear decay shifted to few body systems. Data on the decay of 5 /sub Λ/He was taken along with preliminary data on 4 /sub Λ/He. This was followed a month later by a run at LEAR to study anti ΛΛ production. The high statistics runs should allow extraction of the spin correlation coefficients not previously obtainable and also includes a detailed study at threshold. In December, a second run at LEAR began the start of anti ΛΣ production studies and tested the ability to measure K/sub s/K/sub s/ production; this channel will be used to search for the ξ(2230) in the summer of 1986. In preparation for the ξ(2230) search, extensive Monte Carlo simulations have been performed at CMU to aid in the design of the detector system. Data analysis routines from hyperon production studies were modified and the first K/sub s/K/sub s/ event was extracted from existing data. The CMU group has had extensive involvement in an experiment to search for strangeness production relativistic heavy ion collisions. Hardware to provide the online analysis and data storage facilities for the experiment has been purchased and developed. CMU personnel has also worked on the development of software with the flexibility required to monitor this complex experiment. 37 refs., 53 figs., 8 tabs

Spin polarized electronic states and spin textures at the surface of oxygen-deficient SrTiO3

Science.gov (United States)

Jeschke, Harald O.; Altmeyer, Michaela; Rozenberg, Marcelo; Gabay, Marc; Valenti, Roser

We investigate the electronic structure and spin texture at the (001) surface of SrTiO3 in the presence of oxygen vacancies by means of ab initio density functional theory (DFT) calculations of slabs. Relativistic non-magnetic DFT calculations exhibit Rashba-like spin winding with a characteristic energy scale ~ 10 meV. However, when surface magnetism on the Ti ions is included, bands become spin-split with an energy difference ~ 100 meV at the Γ point. This energy scale is comparable to the observations in SARPES experiments performed on the two-dimensional electronic states confined near the (001) surface of SrTiO3. We find the spin polarized state to be the ground state of the system, and while magnetism tends to suppress the effects of the relativistic Rashba interaction, signatures of it are still clearly visible in terms of complex spin textures. We gratefully acknowledge financial support from the Deutsche Forschungsgemeinschaft through grants SFB/TR 49 and FOR 1346.

Some topics concerning N--N and N--D experiments at medium energy

International Nuclear Information System (INIS)

Simmons, J.E.

1975-01-01

The status of recent proton-proton phase shift analyses is reviewed at medium energy with mention of the state of the n-p I = 0 analyses. Some conclusions are reached, including a recommendation for renewed theoretical effort to calculate absorption parameters for N--N scattering above 300 MeV in higher partial waves (l greater than or equal to 3). Recent experimental data are examined for p-p small angle scattering at 630 MeV and also near 500 MeV. Further small angle experiments on p-p and p-d scattering are deemed desirable. A brief discussion of recent n-p charge exchange experiments is given. Finally, the status of medium to high energy (100 to 2000 MeV) p-d elastic scattering is reviewed with emphasis on back angle scattering and the usefulness of p-d polarization measurements. (1 table, 12 figures, 94 references) (U.S.)

Medium-energy physics program. Progress report, August 1--October 31, 1977

Energy Technology Data Exchange (ETDEWEB)

van Dyck, O.B.; Dunn, E.D. (comps.)

1978-05-01

A report is given of the medium-energy physics program at the LAMPF linac for the period from August 1 through October 31, 1977. Topics discussed include: (1) accelerator facilities and development; (2) the main beam lines; (3) experimental areas; (4) research; (5) nuclear chemistry; (6) practical applications; (7) linac technology; and (8) management. (PMA)

Medium-energy physics program. Progress report, August 1--October 31, 1977

International Nuclear Information System (INIS)

van Dyck, O.B.; Dunn, E.D.

1978-05-01

A report is given of the medium-energy physics program at the LAMPF linac for the period from August 1 through October 31, 1977. Topics discussed include: (1) accelerator facilities and development; (2) the main beam lines; (3) experimental areas; (4) research; (5) nuclear chemistry; (6) practical applications; (7) linac technology; and (8) management

Mechanical generation of spin current

Directory of Open Access Journals (Sweden)

Mamoru eMatsuo

2015-07-01

Full Text Available We focus the recent results on spin-current generation from mechanical motion such as rigid rotation and elastic deformations. Spin transport theory in accelerating frames is constructed by using the low energy expansion of the generally covariant Dirac equation. Related issues on spin-manipulation by mechanical rotation are also discussed.

Measurement of the spin-spin correlation parameter C/sub LL/(THETA) in proton-proton scattering

International Nuclear Information System (INIS)

Stuart, S.J.

1982-08-01

The experimental procedures and methods of data analysis used to measure the spin-spin correlation parameter C/sub LL/(THETA) in proton-proton scattering at thirteen different energies in the range 300 to 800 MeV are presented. The results compare favorably with previous data. Good agreement is found with phase shift predictions at energies below 500 MeV

Radiation reaction for spinning bodies in effective field theory. I. Spin-orbit effects

Science.gov (United States)

Maia, Natália T.; Galley, Chad R.; Leibovich, Adam K.; Porto, Rafael A.

2017-10-01

We compute the leading post-Newtonian (PN) contributions at linear order in the spin to the radiation-reaction acceleration and spin evolution for binary systems, which enter at fourth PN order. The calculation is carried out, from first principles, using the effective field theory framework for spinning compact objects, in both the Newton-Wigner and covariant spin supplementary conditions. A nontrivial consistency check is performed on our results by showing that the energy loss induced by the resulting radiation-reaction force is equivalent to the total emitted power in the far zone, up to so-called "Schott terms." We also find that, at this order, the radiation reaction has no net effect on the evolution of the spins. The spin-spin contributions to radiation reaction are reported in a companion paper.

Spin-dependent energy distribution of B-hadrons from polarized top decays considering the azimuthal correlation rate

Directory of Open Access Journals (Sweden)

S.M. Moosavi Nejad

2016-04-01

Full Text Available Basically, the energy distribution of bottom-flavored hadrons produced through polarized top quark decays t(↑→W++b(→Xb, is governed by the unpolarized rate and the polar and the azimuthal correlation functions which are related to the density matrix elements of the decay t(↑→bW+. Here we present, for the first time, the analytical expressions for the O(αs radiative corrections to the differential azimuthal decay rates of the partonic process t(↑→b+W+ in two helicity systems, which are needed to study the azimuthal distribution of the energy spectrum of the hadrons produced in polarized top decays. These spin-momentum correlations between the top quark spin and its decay product momenta will allow the detailed studies of the top decay mechanism. Our predictions of the hadron energy distributions also enable us to deepen our knowledge of the hadronization process and to test the universality and scaling violations of the bottom-flavored meson fragmentation functions.

Spin symmetry in the relativistic symmetrical well potential including a proper approximation to the spin-orbit coupling term

International Nuclear Information System (INIS)

Wei Gaofeng; Dong Shihai

2010-01-01

In the case of exact spin symmetry, we approximately solve the Dirac equation with scalar and vector symmetrical well potentials by using a proper approximation to the spin-orbit coupling term, and obtain the corresponding energy equation and spinor wave functions for the bound states. We find that there exist only positive-energy bound states in the case of spin symmetry. Also, the energy eigenvalue approaches a constant when the potential parameter α goes to zero. The special case for equally scalar and vector symmetrical well potentials is studied briefly.

Spin helical states and spin transport of the line defect in silicene lattice

Energy Technology Data Exchange (ETDEWEB)

Yang, Mou; Chen, Dong-Hai; Wang, Rui-Qiang [Laboratory of Quantum Engineering and Quantum Materials, School of Physics and Telecommunication Engineering, South China Normal University, Guangzhou 510006 (China); Bai, Yan-Kui, E-mail: ykbai@semi.ac.cn [College of Physical Science and Information Engineering and Hebei Advance Thin Films Laboratory, Hebei Normal University, Shijiazhuang, Hebei 050024 (China)

2015-02-06

We investigated the electronic structure of a silicene-like lattice with a line defect under the consideration of spin–orbit coupling. In the bulk energy gap, there are defect related bands corresponding to spin helical states localized beside the defect line: spin-up electrons flow forward on one side near the line defect and move backward on the other side, and vice versa for spin-down electrons. When the system is subjected to random distribution of spin-flipping scatterers, electrons suffer much less spin-flipped scattering when they transport along the line defect than in the bulk. An electric gate above the line defect can tune the spin-flipped transmission, which makes the line defect as a spin-controllable waveguide. - Highlights: • Band structure of silicene with a line defect. • Spin helical states around the line defect and their probability distribution features. • Spin transport along the line defect and that in the bulk silicene.

Spin-Triplet Pairing Induced by Spin-Singlet Interactions in Noncentrosymmetric Superconductors

Science.gov (United States)

Matsuzaki, Tomoaki; Shimahara, Hiroshi

2017-02-01

In noncentrosymmetric superconductors, we examine the effect of the difference between the intraband and interband interactions, which becomes more important when the band splitting increases. We define the difference ΔVμ between their coupling constants, i.e., that between the intraband and interband hopping energies of intraband Cooper pairs. Here, the subscript μ of ΔVμ indicates that the interactions scatter the spin-singlet and spin-triplet pairs when μ = 0 and μ = 1,2,3, respectively. It is shown that the strong antisymmetric spin-orbit interaction reverses the target spin parity of the interaction: it converts the spin-singlet and spin-triplet interactions represented by ΔV0 and ΔVμ>0 into effective spin-triplet and spin-singlet pairing interactions, respectively. Hence, for example, triplet pairing can be induced solely by the singlet interaction ΔV0. We name the pairing symmetry of the system after that of the intraband Cooper pair wave function, but with an odd-parity phase factor excluded. The pairing symmetry must then be even, even for the triplet component, and the following results are obtained. When ΔVμ is small, the spin-triplet p-wave interactions induce spin-triplet s-wave and spin-triplet d-wave pairings in the regions where the repulsive singlet s-wave interaction is weak and strong, respectively. When ΔV0 is large, a repulsive interband spin-singlet interaction can stabilize spin-triplet pairing. When the Rashba interaction is adopted for the spin-orbit interaction, the spin-triplet pairing interactions mediated by transverse magnetic fluctuations do not contribute to triplet pairing.

Quantum nutation of the neutron spin

International Nuclear Information System (INIS)

Pleshanov, N.K.

2000-01-01

The possibility to prepare the spin particle in a state, which is a superposition of two states with different energies (in contrast to the classical particle, the energy of which is definite in any time and position) gives a purely quantum condition for the nutation behavior of its spin

Spin Conference

International Nuclear Information System (INIS)

Anon.

1983-01-01

The 5th International Symposium on High Energy Spin Physics met in September at Brookhaven. The symposium has evolved to include a number of diverse specialities: theory, including parity violations and proposed quantum chromodynamics (QCD) tests with polarized beams; experiment, including the large spin effects discovered in high transverse momentum elastic scattering and hyperon production, dibaryons, and magnetic moments; acceleration and storage of polarized protons and electrons; and development of polarized sources and targets

Unidirectional spin-wave heat conveyer.

Science.gov (United States)

An, T; Vasyuchka, V I; Uchida, K; Chumak, A V; Yamaguchi, K; Harii, K; Ohe, J; Jungfleisch, M B; Kajiwara, Y; Adachi, H; Hillebrands, B; Maekawa, S; Saitoh, E

2013-06-01

When energy is introduced into a region of matter, it heats up and the local temperature increases. This energy spontaneously diffuses away from the heated region. In general, heat should flow from warmer to cooler regions and it is not possible to externally change the direction of heat conduction. Here we show a magnetically controllable heat flow caused by a spin-wave current. The direction of the flow can be switched by applying a magnetic field. When microwave energy is applied to a region of ferrimagnetic Y3Fe5O12, an end of the magnet far from this region is found to be heated in a controlled manner and a negative temperature gradient towards it is formed. This is due to unidirectional energy transfer by the excitation of spin-wave modes without time-reversal symmetry and to the conversion of spin waves into heat. When a Y3Fe5O12 film with low damping coefficients is used, spin waves are observed to emit heat at the sample end up to 10 mm away from the excitation source. The magnetically controlled remote heating we observe is directly applicable to the fabrication of a heat-flow controller.

Spin Waves in Terbium

DEFF Research Database (Denmark)

Jensen, J.; Houmann, Jens Christian Gylden; Bjerrum Møller, Hans

1975-01-01

with the symmetry, we deduce the dispersion relation for the spin waves in a basal-plane ferromagnet. This phenomenological spin-wave theory accounts for the observed behavior of the magnon energies in Tb. The two q⃗-dependent Bogoliubov components of the magnon energies are derived from the experimental results......, which are corrected for the effect of the direct coupling between the magnons and the phonons, and for the field dependence of the relative magnetization at finite temperatures. A large q⃗-dependent difference between the two energy components is observed, showing that the anisotropy of the two...

Charged spinning black holes as particle accelerators

International Nuclear Information System (INIS)

Wei Shaowen; Liu Yuxiao; Guo Heng; Fu Chune

2010-01-01

It has recently been pointed out that the spinning Kerr black hole with maximal spin could act as a particle collider with arbitrarily high center-of-mass energy. In this paper, we will extend the result to the charged spinning black hole, the Kerr-Newman black hole. The center-of-mass energy of collision for two uncharged particles falling freely from rest at infinity depends not only on the spin a but also on the charge Q of the black hole. We find that an unlimited center-of-mass energy can be approached with the conditions: (1) the collision takes place at the horizon of an extremal black hole; (2) one of the colliding particles has critical angular momentum; (3) the spin a of the extremal black hole satisfies (1/√(3))≤(a/M)≤1, where M is the mass of the Kerr-Newman black hole. The third condition implies that to obtain an arbitrarily high energy, the extremal Kerr-Newman black hole must have a large value of spin, which is a significant difference between the Kerr and Kerr-Newman black holes. Furthermore, we also show that, for a near-extremal black hole, there always exists a finite upper bound for center-of-mass energy, which decreases with the increase of the charge Q.

Analytic evidence of the equivalence of the alternating Heisenberg spin chain to the mixed spin (1, 1/2) Heisenberg chain

International Nuclear Information System (INIS)

Jiang Jianjun; Liu Yongjun; Tang Fei; Yang Cuihong

2011-01-01

We investigated the properties of the spin-1/2 ferromagnetic-antiferromagnetic-antiferromagnetic alternating Heisenberg chain using the spin-wave theory. The spin-wave excitation spectra, the sublattice magnetizations and the local bond energies of the model are calculated to be compared with the corresponding properties of the mixed spin (1, 1/2) chain for a range of α. The results demonstrate that all the properties show similar behaviours in the small α limit, so the properties of the mixed spin (1, 1/2) chain can be described using the spin-1/2 ferromagnetic-antiferromagnetic-antiferromagnetic alternating Heisenberg chain. -- Research Highlights: →The spin-wave excitation spectra, the sublattice magnetizations and the local bond energies of the spin-1/2 ferromagnetic-antiferromagnetic-antiferromagnetic alternating Heisenberg chain are calculated. →In the small α limit, the properties of the mixed spin (1,1/2) chain can be described using the spin-1/2 ferromagnetic-antiferromagnetic-antiferromagnetic alternating Heisenberg chain. →The spin-1/2 ferromagnetic-antiferromagnetic-antiferromagnetic alternating Heisenberg chain may be of interest for some real quasi-one-dimensional molecular magnetic materials.

Emission of medium-heavy fragments in asymetric heavy ion collisions at intermediate and relativistic incident energies

International Nuclear Information System (INIS)

Milkau, T.U.E.

1991-11-01

For the study of the emission of medium-heavy fragments in asymmetric heavy ion collisions a series of experiments was performed and thereby following systems at intermediate and relativistic incident energies studied: 84 Kr+ 197 Au at E/A=35 MeV, 40 Ar+ 197 Au at E/A=30 MeV, respectively 220 MeV, and 12 C+ 197 Au at E/A=99 MeV, 301 MeV, 601 MeV, respectively 1105 MeV. In the experiments highly resolving detector telescopes with low thresholds were applied to the measurement of the energy and angular distributions of the medium-heavy fragments. The spectra were analyzed in the picture of longitudinally moving sources. Thereby beyond the production cross sections the angular distributions, the decreasement parameters in the high-energetic region of the energy spectra, and the position of the maxima were determined as characteristic parameters. The following picture resulted: The production cross sections for medium-heavy fragments showed a steep increasement and then a saturation, but with a strong projectile dependence. The charge distributions could be described by a power law, the parameter of which showed a universal dependence on the total incident energy. In the angular distributions the transition from an anisotropic emission at low energies to an isotropic emission from a nearly resting source at relativistic energies was distinctly to be recognized. The decreasement parameters of the energy distribution increased - for different projectiles differently strongly - logarithmically with growing incident energy. And the maxima of the energy distribution travelled with growing incident energy to smaller and smaller fragment energies. From this systematics a schematic model of the fragmentation can be obtained. (orig./HSI) [de

Spin-filter and spin-gapless semiconductors: The case of Heusler compounds

International Nuclear Information System (INIS)

Galanakis, I.; Özdoğan, K.; Şaşıoğlu, E.

2016-01-01

We review our recent first-principles results on the inverse Heusler compounds and the ordered quaternary (also known as LiMgPdSn-type) Heusler compounds. Among these two subfamilies of the full-Heusler compounds, several have been shown to be magnetic semiconductors. Such material can find versatile applications, e.g. as spin-filter materials in magnetic tunnel junctions. Finally, a special case are the spin-gapless semiconductors, where the energy gap at the Fermi level for the one spin-direction is almost vanishing, offering novel functionalities in spintronic/magnetoelectronic devices.

Long distance spin communication in chemical vapour deposited graphene

Science.gov (United States)

Kamalakar, M. Venkata; Groenveld, Christiaan; Dankert, André; Dash, Saroj P.

2015-04-01

Graphene is an ideal medium for long-distance spin communication in future spintronic technologies. So far, the prospect is limited by the smaller sizes of exfoliated graphene flakes and lower spin transport properties of large-area chemical vapour-deposited (CVD) graphene. Here we demonstrate a high spintronic performance in CVD graphene on SiO2/Si substrate at room temperature. We show pure spin transport and precession over long channel lengths extending up to 16 μm with a spin lifetime of 1.2 ns and a spin diffusion length ~6 μm at room temperature. These spin parameters are up to six times higher than previous reports and highest at room temperature for any form of pristine graphene on industrial standard SiO2/Si substrates. Our detailed investigation reinforces the observed performance in CVD graphene over wafer scale and opens up new prospects for the development of lateral spin-based memory and logic applications.

Spin-polarization and spin-dependent logic gates in a double quantum ring based on Rashba spin-orbit effect: Non-equilibrium Green's function approach

International Nuclear Information System (INIS)

Eslami, Leila; Esmaeilzadeh, Mahdi

2014-01-01

Spin-dependent electron transport in an open double quantum ring, when each ring is made up of four quantum dots and threaded by a magnetic flux, is studied. Two independent and tunable gate voltages are applied to induce Rashba spin-orbit effect in the quantum rings. Using non-equilibrium Green's function formalism, we study the effects of electron-electron interaction on spin-dependent electron transport and show that although the electron-electron interaction induces an energy gap, it has no considerable effect when the bias voltage is sufficiently high. We also show that the double quantum ring can operate as a spin-filter for both spin up and spin down electrons. The spin-polarization of transmitted electrons can be tuned from −1 (pure spin-down current) to +1 (pure spin-up current) by changing the magnetic flux and/or the gates voltage. Also, the double quantum ring can act as AND and NOR gates when the system parameters such as Rashba coefficient are properly adjusted

The influence of further-neighbor spin-spin interaction on a ground state of 2D coupled spin-electron model in a magnetic field

Science.gov (United States)

Čenčariková, Hana; Strečka, Jozef; Gendiar, Andrej; Tomašovičová, Natália

2018-05-01

An exhaustive ground-state analysis of extended two-dimensional (2D) correlated spin-electron model consisting of the Ising spins localized on nodal lattice sites and mobile electrons delocalized over pairs of decorating sites is performed within the framework of rigorous analytical calculations. The investigated model, defined on an arbitrary 2D doubly decorated lattice, takes into account the kinetic energy of mobile electrons, the nearest-neighbor Ising coupling between the localized spins and mobile electrons, the further-neighbor Ising coupling between the localized spins and the Zeeman energy. The ground-state phase diagrams are examined for a wide range of model parameters for both ferromagnetic as well as antiferromagnetic interaction between the nodal Ising spins and non-zero value of external magnetic field. It is found that non-zero values of further-neighbor interaction leads to a formation of new quantum states as a consequence of competition between all considered interaction terms. Moreover, the new quantum states are accompanied with different magnetic features and thus, several kinds of field-driven phase transitions are observed.

Medium-energy physics program. Progress report, February 1--April 1, 1976

Energy Technology Data Exchange (ETDEWEB)

Dunn, E. (comp.)

1976-09-01

A quarterly report on the medium-energy physics program at LAMPF is given. Topics covered include: (1) engineering support; (2) accelerator support; (3) accelerator systems development; (4) injector systems; (5) electronic instrumentation and computer systems; (6) accelerator operations; (7) experimental areas; (8) beam line development; (9) large-spectrometer systems; (10) research; (11) nuclear chemistry; (12) practical applications of LAMPF; and (13) management. (PMA)

Medium-energy physics program. Progress report, February 1--April 1, 1976

International Nuclear Information System (INIS)

Dunn, E.

1976-09-01

A quarterly report on the medium-energy physics program at LAMPF is given. Topics covered include: (1) engineering support; (2) accelerator support; (3) accelerator systems development; (4) injector systems; (5) electronic instrumentation and computer systems; (6) accelerator operations; (7) experimental areas; (8) beam line development; (9) large-spectrometer systems; (10) research; (11) nuclear chemistry; (12) practical applications of LAMPF; and (13) management

Spin crossover and high spin filtering behavior in Co-Pyridine and Co-Pyrimidine molecules

Science.gov (United States)

Wen, Zhongqian; Zhou, Liping; Cheng, Jue-Fei; Li, Shu-Jin; You, Wen-Long; Wang, Xuefeng

2018-03-01

We present a theoretical study on a series of cobalt complexes, which are constructed with cobalt atoms and pyridine/pyrimidine rings, using density functional theory. We investigate the structural and electric transport properties of spin crossover (SCO) Co complex with two spin states, namely low-spin configuration [LS] and high-spin configuration [HS]. Energy analyses of the two spin states imply that the SCO Co-Pyridine2 and Co-Pyrimidine2 complexes may display a spin transition process accompanied by a geometric modification driven by external stimuli. A nearly perfect spin filtering effect is observed in the Co-Pyrimidine2 complex with [HS] state. In addition, we also discover the contact-dependent transmission properties of Co-Pyridine2. These findings indicate that SCO Co complexes are promising materials for molecular spintronic devices.

QCD SPIN PHYSICS IN HADRONIC INTERACTIONS.

Energy Technology Data Exchange (ETDEWEB)

VOGELSANG,W.

2007-06-19

We discuss spin phenomena in high-energy hadronic scattering, with a particular emphasis on the spin physics program now underway at the first polarized proton-proton collider, RHIC. Experiments at RHIC unravel the spin structure of the nucleon in new ways. Prime goals are to determine the contribution of gluon spins to the proton spin, to elucidate the flavor structure of quark and antiquark polarizations in the nucleon, and to help clarify the origin of transverse-spin phenomena in QCD. These lectures describe some aspects of this program and of the associated physics.

Out-of-equilibrium spin transport in mesoscopic superconductors.

Science.gov (United States)

Quay, C H L; Aprili, M

2018-08-06

The excitations in conventional superconductors, Bogoliubov quasi-particles, are spin-[Formula: see text] fermions but their charge is energy-dependent and, in fact, zero at the gap edge. Therefore, in superconductors (unlike normal metals) spin and charge degrees of freedom may be separated. In this article, we review spin injection into conventional superconductors and focus on recent experiments on mesoscopic superconductors. We show how quasi-particle spin transport and out-of-equilibrium spin-dependent superconductivity can be triggered using the Zeeman splitting of the quasi-particle density of states in thin-film superconductors with small spin-mixing scattering. Finally, we address the spin dynamics and the feedback of quasi-particle spin imbalances on the amplitude of the superconducting energy gap.This article is part of the theme issue 'Andreev bound states'. © 2018 The Author(s).

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.

Electron spin resonance and spin-valley physics in a silicon double quantum dot.

Science.gov (United States)

Hao, Xiaojie; Ruskov, Rusko; Xiao, Ming; Tahan, Charles; Jiang, HongWen

2014-05-14

Silicon quantum dots are a leading approach for solid-state quantum bits. However, developing this technology is complicated by the multi-valley nature of silicon. Here we observe transport of individual electrons in a silicon CMOS-based double quantum dot under electron spin resonance. An anticrossing of the driven dot energy levels is observed when the Zeeman and valley splittings coincide. A detected anticrossing splitting of 60 MHz is interpreted as a direct measure of spin and valley mixing, facilitated by spin-orbit interaction in the presence of non-ideal interfaces. A lower bound of spin dephasing time of 63 ns is extracted. We also describe a possible experimental evidence of an unconventional spin-valley blockade, despite the assumption of non-ideal interfaces. This understanding of silicon spin-valley physics should enable better control and read-out techniques for the spin qubits in an all CMOS silicon approach.

Analytical treatment of the spin splitter

International Nuclear Information System (INIS)

Conte, M.; Penzo, A.; Pisent, A.; Pusterla, M.

1988-01-01

The spin-orbit coupling associated with the interaction of the magnetic of proton-antiproton, circulating in a low energy storage ring, with appropriate field gradients of quadrupole elements in the machine, is studied analytically. The conditions for a separation of opposite spin states are discussed and methods are proposed for working at very low energies

Energy Efficiency Market Report 2013: Market Trends and Medium-Term Prospects

Energy Technology Data Exchange (ETDEWEB)

NONE

2013-07-01

Energy efficiency has been referred to as a ''hidden fuel'', one that extends energy supplies, increases energy security, lowers carbon emissions and generally supports sustainable economic growth. Yet it is hiding in plain sight: in 2011, investments in the energy efficiency market globally were at a similar scale to those in renewable energy or fossil-fuel power generation. The Energy Efficiency Market Report provides a practical basis for understanding energy efficiency market activities, a review of the methodological and practical challenges associated with measuring the market and its components, and statistical analysis of energy efficiency and its impact on energy demand. It also highlights a specific technology sector in which there is significant energy efficiency market activity, in this instance appliances and ICT. The report presents a selection of country case studies that illustrate current energy efficiency markets in specific sectors, and how they may evolve in the medium term. The energy efficiency market is diffuse, varied and involves all energy-consuming sectors of the economy. A comprehensive overview of market activity is complicated by the challenges associated with quantifying the components of the market and the paucity of comparable reported data. This report underscores how vital high-quality and timely energy efficiency data is to understanding this market.

Widespread spin polarization effects in photoemission from topological insulators

Energy Technology Data Exchange (ETDEWEB)

Jozwiak, C.; Chen, Y. L.; Fedorov, A. V.; Analytis, J. G.; Rotundu, C. R.; Schmid, A. K.; Denlinger, J. D.; Chuang, Y.-D.; Lee, D.-H.; Fisher, I. R.; Birgeneau, R. J.; Shen, Z.-X.; Hussain, Z.; Lanzara, A.

2011-06-22

High-resolution spin- and angle-resolved photoemission spectroscopy (spin-ARPES) was performed on the three-dimensional topological insulator Bi{sub 2}Se{sub 3} using a recently developed high-efficiency spectrometer. The topological surface state's helical spin structure is observed, in agreement with theoretical prediction. Spin textures of both chiralities, at energies above and below the Dirac point, are observed, and the spin structure is found to persist at room temperature. The measurements reveal additional unexpected spin polarization effects, which also originate from the spin-orbit interaction, but are well differentiated from topological physics by contrasting momentum and photon energy and polarization dependencies. These observations demonstrate significant deviations of photoelectron and quasiparticle spin polarizations. Our findings illustrate the inherent complexity of spin-resolved ARPES and demonstrate key considerations for interpreting experimental results.

Near-field thermal upconversion and energy transfer through a Kerr medium.

Science.gov (United States)

Khandekar, Chinmay; Rodriguez, Alejandro W

2017-09-18

We present an approach for achieving large Kerr χ (3) -mediated thermal energy transfer at the nanoscale that exploits a general coupled-mode description of triply resonant, four-wave mixing processes. We analyze the efficiency of thermal upconversion and energy transfer from mid- to near-infrared wavelengths in planar geometries involving two slabs supporting far-apart surface plasmon polaritons and separated by a nonlinear χ (3) medium that is irradiated by externally incident light. We study multiple geometric and material configurations and different classes of intervening mediums-either bulk or nanostructured lattices of nanoparticles embedded in nonlinear materials-designed to resonantly enhance the interaction of the incident light with thermal slab resonances. We find that even when the entire system is in thermodynamic equilibrium (at room temperature) and under typical drive intensities ~ W/μm 2 , the resulting upconversion rates can approach and even exceed thermal flux rates achieved in typical symmetric and non-equilibrium configurations of vacuum-separated slabs. The proposed nonlinear scheme could potentially be exploited to achieve thermal cooling and refrigeration at the nanoscale, and to actively control heat transfer between materials with dramatically different resonant responses.

Breatherlike electromagnetic wave propagation in an antiferromagnetic medium with Dzyaloshinsky-Moriya interaction

International Nuclear Information System (INIS)

Kavitha, L.; Saravanan, M.; Srividya, B.; Gopi, D.

2011-01-01

We investigate the nature of propagation of electromagnetic waves (EMWs) in an antiferromagnetic medium with Dzyaloshinsky-Moriya (DM) interaction environment. The interplay of bilinear and DM exchange spin coupling with the magnetic field component of the EMW has been studied by solving Maxwell's equations coupled with a nonlinear spin equation for the magnetization of the medium. We made a nonuniform expansion of the magnetization and magnetic field along the direction of propagation of EMW, in the framework of reductive perturbation method, and the dynamics of the system is found to be governed by a generalized derivative nonlinear Schroedinger (DNLS) equation. We employ the Jacobi-elliptic function method to solve the DNLS equation, and the electromagnetic wave propagation in an antiferromagnetic medium is governed by the breatherlike spatially and temporally coherent localized modes under the influence of DM interaction parameter.

A new spin on causality constraints

Energy Technology Data Exchange (ETDEWEB)

Hartman, Thomas; Jain, Sachin; Kundu, Sandipan [Department of Physics, Cornell University, Ithaca, New York (United States)

2016-10-26

Causality in a shockwave state is related to the analytic properties of a four-point correlation function. Extending recent results for scalar probes, we show that this constrains the couplings of the stress tensor to light spinning operators in conformal field theory, and interpret these constraints in terms of the interaction with null energy. For spin-1 and spin-2 conserved currents in four dimensions, the resulting inequalities are a subset of the Hofman-Maldacena conditions for positive energy deposition. It is well known that energy conditions in holographic theories are related to causality on the gravity side; our results make a connection on the CFT side, and extend it to non-holographic theories.

Spin dynamics in electron synchrotrons; Spindynamik in Elektronensynchrotronen

Energy Technology Data Exchange (ETDEWEB)

Schmidt, Jan Felix

2017-07-14

Providing spin polarized particle beams with circular accelerators requires the consideration of depolarizing resonances which may significantly reduce the desired degree of polarization at specific beam energies. The corresponding spin dynamical effects are typically analyzed with numerical methods. In case of electron beams the influence of the emission of synchrotron radiation has to be taken into account. On short timescales, as in synchrotrons with a fast energy ramp or in damping rings, spin dynamics are investigated with spin tracking algorithms. This thesis presents the spin tracking code Polematrix as a versatile tool to study the impact of synchrotron radiation on spin dynamics. Spin tracking simulations have been performed based on the well established particle tracking code Elegant. The numerical studies demonstrate effects which are responsible for beam depolarization: Synchrotron side bands of depolarizing resonances and decoherence of spin precession. Polematrix can be utilized for any electron accelerator with minimal effort as it imports lattice files from the tracking programs MAD-X or Elegant. Polematrix has been published as open source software. Currently, the Electron Stretcher Accelerator ELSA at Bonn University is the only electron synchrotron worldwide providing a polarized beam. Integer and intrinsic depolarizing resonances are compensated with dedicated countermeasures during the fast energy ramp. Polarization measurements from ELSA demonstrate the particular spin dynamics of electrons and confirm the results of the spin tracking code Polematrix.

An intercomparison of medium energy cross-section codes

International Nuclear Information System (INIS)

Pearlstein, S.

1988-05-01

Five medium energy proton reaction cases are selected for benchmarking nuclear model codes. The quantities calculated are isotopic activation yields for 180 MeV protons on Al and 40-200 MeV protons on Co, and double differential neutron emission spectra from Al, Zr-90 and Pb-208 for 35, 80, 160, 318, and 800 presented consist of three types: a closed form preequilibrium plus evaporation model, an intranuclear-cascade and evaporation model, and a model relying on nuclear systematics. The characteristics of each code are described. There are orders of magnitude differences in the time for each type of code to calculate neutron emission spectra, with codes using systematics, preequilibrium and intranuclear-cascade models requiring seconds, minutes and hours, respectively. Calculations are not compared with experiment in this initial study. For double differential neutron emission spectra, there is good overall agreement in magnitude among the different types of codes at forward angles. Differences where they occur at forward angles are greatest for the mid-energy neutrons emitted. At back angles the incident energy at which the best overall agreement is obtained is 160 MeV and the material for which the best overall agreement is obtained is Al. 4 refs., 7 tabs

Classical spins in superconductors

Energy Technology Data Exchange (ETDEWEB)

Shiba, H [Tokyo Univ.; Maki, K

1968-08-01

It is shown that there exists a localized excited state in the energy gap in a superconductor with a classical spin. At finite concentration localized excited states around classical spins form an impurity band. The process of growth of the impurity band and its effects on observable quantities are investigated.

Medium energy measurements of N-N parameters

International Nuclear Information System (INIS)

Ambrose, D.; Bachman, M.; Coffey, P.; Glass, G.; Jobst, B.; McNaughton, Kok Heong; Nguyen, Chau; Riley, P.J.

1993-01-01

Most of the effort was devoted to the study of nucleon-nucleon interactions, specifically, spin transfer measurements in np elastic scattering at LAMPF, pp elastic differential cross section measurements at LAMPF, and single-pion production in np scattering. Differential cross sections and analyzing powers are shown for np→ppπ - interactions. A new search for rare K L 0 decays to μe, μμ, and ee is being undertaken. Collaborative work has been begun on a very large, complex collider detector STAR (Solenoidal Tracker At RHIC). STAR is envisioned as a combination of a silicon vertex tracker, a time projection chamber, a set of trigger scintillators, and time-of-flight counters. It would allow measurements of spin dependence at p T above 10 GeV/c

Spin assignments of nuclear levels above the neutron binding energy in $^{88}$Sr

CERN Multimedia

Neutron resonances reveal nuclear levels in the highly excited region of the nucleus around the neutron binding energy. Nuclear level density models are therefore usually calibrated to the number of observed levels in neutron-induced reactions. The gamma-ray cascade from the decay of the highly excited compound nucleus state to the ground state show dierences dependent on the initial spin. This results in a dierence in the multiplicity distribution which can be exploited. We propose to use the 4${\\pi}$ total absorption calorimeter (TAC) at the n TOF facility to determine the spins of resonances formed by neutrons incident on a metallic $^{87}$Sr sample by measuring the gamma multiplicity distributions for the resolved resonances. In addition we would like to use the available enriched $^{87}$Sr target for cross section measurements with the C$\\scriptscriptstyle{6}$D$\\scriptscriptstyle{6}$ detector setup.

Beacon-S TM: Non-uniform attenuation correction for SPECT imaging. The new medium-energy transmission device for AXIS and IRIX

International Nuclear Information System (INIS)

Daniel Gagnon, D.

1999-01-01

The paper presents new medium-energy transmission device for SPECT imaging. Beacon-S includes a 356-keV medium energy 133 Ba source with a 10.54-year half-life. Beacon-S provide high-resolution and high-contrast transmission scans. The higher energy of the gamma substantially improves the transmission contrast for larger patients by virtue of better penetration through the body

Fiscal 1999 survey report on long-term energy technological strategies and the like. Long-term energy technological strategy survey (Medium-term energy technological strategy survey); 1999 nendo choki energy gijutsu senryaku nado ni kansuru chosa hokokusho. Choki energy gijutsu senryaku chosa (chuki energy gijutsu senryaku chosa)

Energy Technology Data Exchange (ETDEWEB)

NONE

2000-03-01

Energy strategies to be implemented under the New Sunshine Program by around 2010 have been compiled, with nation's industrial technological strategies, long-term energy outlook, and the like taken into consideration. The present survey aims to work out medium-term energy technological strategies. In Chapter 2, by conducting studies on the state of energy strategies in the national industry technological strategies as primarily compiled, long-term energy supply and demand outlook, and the history so far of the New Sunshine Program, and social conditions surrounding energy/environmental technologies and energy conditions are arranged in order and then analyzed with a view to deriving social needs. In Chapter 3, in view of the derived social needs, medium-term energy technological strategies are broken down into strategic target details, based on the important regions and major and minor strategic targets of the national industry technological strategies. In Chapter 4, medium-term energy technological strategies are worked out. In Chapter 5, 'basic ideas,' 'measures for promoting technology development,' 'return of the fruits to society' are mentioned as the methods of realizing the strategies. In Chapter 6, surveys and researches are summarized, and future development is predicted. (NEDO)

Helical spin rotators and snakes for RHIC

International Nuclear Information System (INIS)

Ptitsin, V.I.; Shatunov, Yu.M.; Peggs, S.

1995-01-01

The RHIC collider, now under construction at BNL, will have the possibility of polarized proton-proton collisions up to a beam energy of 250 Gev. Polarized proton beams of such high energy can be only obtained with the use of siberian snakes, a special kind of spin rotator that rotates the particle spin by 180 degree around an axis lying in the horizontal plane. Siberian snakes help to preserve the beam polarization while numerous spin depolarizing resonances are crossed, during acceleration. In order to collide longitudinally polarized beams, it is also planned to install spin rotators around two interaction regions. This paper discusses snake and spin rotator designs based on sequences of four helical magnets. The schemes that were chosen to be applied at RHIC are presented

Spinning fluids in general relativity: a variational formulation

International Nuclear Information System (INIS)

Oliveira, H.P. de; Salim, J.M.

1990-01-01

In this paper we present a variational formulation for spinning fluids in General Relativity. In our model each volume element of the fluid has rigid microstructure. We deduce a symmetrical energy-moment tensor where there is an explicit contribution of kinetic spin energy to the total energy. (author)

An enhancement of spin polarization by multiphoton pumping in semiconductors

Energy Technology Data Exchange (ETDEWEB)

Miah, M. Idrish, E-mail: m.miah@griffith.edu.au [Queensland Micro- and Nanotechnology Centre, Griffith University, Nathan, Brisbane, QLD 4111 (Australia); Department of Physics, University of Chittagong, Chittagong 4331 (Bangladesh)

2011-08-15

Highlights: {yields} Multiphoton pumping and spin generation in semiconductors. {yields} Optical selection rules for inter-band transitions. {yields} Calculations of spin polarization using band-energy model and the second order perturbation theory. {yields} Enhancement of the electronic spin polarization. - Abstract: A pump-probe spectroscopic study has been carried out in zinc-blende bulk semiconductors. In the semiconductor samples, a spin-polarized carrier population is produced by the absorption of a monochromatic circularly polarized light beam with two-photon energy above the direct band gap in bulk semiconductors. The production of a carrier population with a net spin is a consequence of the optical selection rules for the heavy-hole and light-hole valence-to-conduction band transitions. This production is probed by the spin-dependent transmission of the samples in the time domain. The spin polarization of the conduction-band-electrons in dependences of delay of the probe beam as well as of pumping photon energy is estimated. The spin polarization is found to depolarize rapidly for pumping energy larger than the energy gap of the split-off band to the conduction band. From the polarization decays, the spin relaxation times are also estimated. Compared to one-photon pumping, the results, however, show that an enhancement of the spin-polarization is achieved by multiphoton excitation of the samples. The experimental results are compared with those obtained in calculations using second order perturbation theory of the spin transport model. A good agreement between experiment and theory is obtained. The observed results are discussed in details.

An enhancement of spin polarization by multiphoton pumping in semiconductors

International Nuclear Information System (INIS)

Miah, M. Idrish

2011-01-01

Highlights: → Multiphoton pumping and spin generation in semiconductors. → Optical selection rules for inter-band transitions. → Calculations of spin polarization using band-energy model and the second order perturbation theory. → Enhancement of the electronic spin polarization. - Abstract: A pump-probe spectroscopic study has been carried out in zinc-blende bulk semiconductors. In the semiconductor samples, a spin-polarized carrier population is produced by the absorption of a monochromatic circularly polarized light beam with two-photon energy above the direct band gap in bulk semiconductors. The production of a carrier population with a net spin is a consequence of the optical selection rules for the heavy-hole and light-hole valence-to-conduction band transitions. This production is probed by the spin-dependent transmission of the samples in the time domain. The spin polarization of the conduction-band-electrons in dependences of delay of the probe beam as well as of pumping photon energy is estimated. The spin polarization is found to depolarize rapidly for pumping energy larger than the energy gap of the split-off band to the conduction band. From the polarization decays, the spin relaxation times are also estimated. Compared to one-photon pumping, the results, however, show that an enhancement of the spin-polarization is achieved by multiphoton excitation of the samples. The experimental results are compared with those obtained in calculations using second order perturbation theory of the spin transport model. A good agreement between experiment and theory is obtained. The observed results are discussed in details.

Nuclear structure and reaction studies at medium energies

International Nuclear Information System (INIS)

Hoffmann, G.W.; Ray, R.L.

1990-10-01

This document constitutes the (1988--1991) technical progress report for the ongoing medium energy physics research program supported by the US Department of Energy through special Research Grant FG05-88ER40444. The experiments discussed are conducted at the Los Alamos National Laboratory's (LANL) Clinton P. Anderson Meson Physics Facility (LAMPF), the Alternating Gradient Synchrotron (AGS) facility of the Brookhaven National Laboratory (BNL), and at the Fermi National Accelerator Laboratory (FNAL). The overall motivation for the work discussed in this document is driven by three main objectives: (1) provide hadron-nucleon and hadron-nucleus scattering data which serve to facilitate the study of effective two-body interactions, test (and possibly determine) nuclear structure, and help study reaction mechanisms and dynamics;(2) provide unique, first-of-a-kind ''exploratory'' hadron-nucleus scattering data in the hope that such data will lead to discovery of new phenomena and new physics; and (3) perform precision tests of fundamental interactions, such as rare decay searches, whose observation would imply fundamental new physics

A possible interaction between spin-1/2 and spin-3/2 fields

International Nuclear Information System (INIS)

Fleury, N.; Lopes, J.L.

1984-01-01

A straighforward extension of the standard Weinberg-Salam model to Rarita-Schwinger formalism, is a heuristic way to obtain electroweak currents for spin-3/2 leptons. A new interaction between spin-1/2 and spin-3/2 particles that maintains the SU(2) x U(1) gauge invariance is postulated and a possible form for the interaction involving these two types of particles and the gauge fields is obtained. This takes place through a coupling which involves derivatives of the electromagnetic field and the corresponding coupling constant is inversely proportional to the mass of spin-3/2 particles. Several reactions are possible with this new interaction such as the radiative decay of a charged Rarita-Schwinger particle. Other reactions are corrections to well-known processes: for instance, in the usual Compton effect, the fermionic virtual line can be replaced by the corresponding spin-3/2 one. But, due to the large mass of the spin-3/2 lepton, these corrections are significantly non negligible only at ultra relativistic energies. On the other hand, in the low energy limit this correction gives fortunately no contribution to the Thomson cross section because the coupling 3/2 - 1/2 - γ is proportional to the photon's momentum. If it is considered all the possible couplings of these fields, one can combine them in diagrams of lowest orders whose theoretical predictions have to be submitted to experimental pressure. (Author) [pt

A possible interaction between spin-1/2 and spin-3/2 fields

International Nuclear Information System (INIS)

Fleury, N.; Leite Lopes, J.

1984-01-01

A straightforward extension of the standard Weinberg-Salam model to Rarita-Schwinger formalism, is a heuristic way to obtain electroweak currents for spin-3/2 leptons. We postulate a new interaction between spin-1/2 and spin-3/2 particles that maintains the SU(2) x U(1) gauge invariance, and we obtain a possible form for the interaction involving these two types of particles and the gauge fields. This takes place through a coupling which involves derivatives of the electromagnetic field and the corresponding coupling constant is inversely proportional to the mass of spin-3/2 particles. Several reactions are possible with this new interaction such as the radiative decay of a charged Rarita-Schwinger particle. Other reactions are corrections to well-known processes: for instance, in the usual Compton effect, the fermionic virtual line can be replaced by the corresponding spin-3/2 one. But, due to the large mass of the spin-3/2 lepton, these corrections are significantly non negligible only at ultra relativistic energies. On the other hand, in the low energy limit this correction gives fortunately no contribution to the Thomson cross section because the coupling 3/2-1/2-γ is proportional to the photon's momentum. If one considers all the possible couplings of these fields, one can combine them in diagrams of lowest orders whose theoretical predictions have to be submitted to experimental pressure

Theoretical interpretation of medium energy nucleon nucleus inelastic scattering

International Nuclear Information System (INIS)

Lagrange, Christian

1970-06-01

A theoretical study is made of the medium energy nucleon-nucleus inelastic scattering (direct interaction), by applying the distorted wave Born approximation such as can be deduced from the paired equation method. It is applied to the interpretation of the inelastic scattering of 12 MeV protons by 63 Cu; this leads us to make use of different sets of wave functions to describe the various states of the target nucleus. We analyze the nature of these states and the shape of the nucleon-nucleus interaction potential, and we compare the results with those obtained from other theoretical and experimental work. (author) [fr

Interplay between bulk medium evolution and (D)GLV energy loss

International Nuclear Information System (INIS)

Molnar, Denes; Sun, Deke

2014-01-01

We study the consistency between high-p T nuclear suppression (R AA ) and elliptic flow (v 2 ) using Gyulassy–Levai–Vitev (GLV) energy loss or a simpler power-law dE/dL formula, for a variety of bulk evolution models. The results generally confirm our earlier work [1] that found suppressed elliptic flow for transversely expanding media. One exception is the set of hydrodynamic solutions used recently [2] by Betz and Gyulassy, which give significantly higher v 2 but unfortunately assume unrealistic bag-model equation of state. On the other hand, we show that covariant treatment of energy loss introduces an interplay between jet direction and hydrodynamic flow of the medium, which largely counteracts elliptic flow suppression caused by transverse expansion

Polarization of nuclear spins by a cold nanoscale resonator

International Nuclear Information System (INIS)

Butler, Mark C.; Weitekamp, Daniel P.

2011-01-01

A cold nanoscale resonator coupled to a system of nuclear spins can induce spin relaxation. In the low-temperature limit where spin-lattice interactions are ''frozen out,'' spontaneous emission by nuclear spins into a resonant mechanical mode can become the dominant mechanism for cooling the spins to thermal equilibrium with their environment. We provide a theoretical framework for the study of resonator-induced cooling of nuclear spins in this low-temperature regime. Relaxation equations are derived from first principles, in the limit where energy donated by the spins to the resonator is quickly dissipated into the cold bath that damps it. A physical interpretation of the processes contributing to spin polarization is given. For a system of spins that have identical couplings to the resonator, the interaction Hamiltonian conserves spin angular momentum, and the resonator cannot relax the spins to thermal equilibrium unless this symmetry is broken by the spin Hamiltonian. The mechanism by which such a spin system becomes ''trapped'' away from thermal equilibrium can be visualized using a semiclassical model, which shows how an indirect spin-spin interaction arises from the coupling of multiple spins to one resonator. The internal spin Hamiltonian can affect the polarization process in two ways: (1) By modifying the structure of the spin-spin correlations in the energy eigenstates, and (2) by splitting the degeneracy within a manifold of energy eigenstates, so that zero-frequency off-diagonal terms in the density matrix are converted to oscillating coherences. Shifting the frequencies of these coherences sufficiently far from zero suppresses the development of resonator-induced correlations within the manifold during polarization from a totally disordered state. Modification of the spin-spin correlations by means of either mechanism affects the strength of the fluctuating spin dipole that drives the resonator. In the case where product states can be chosen as energy

A spin exchange model for singlet fission

Science.gov (United States)

Yago, Tomoaki; Wakasa, Masanobu

2018-03-01

Singlet fission has been analyzed with the Dexter model in which electron exchange occurs between chromophores, conserving the spin for each electron. In the present study, we propose a spin exchange model for singlet fission. In the spin exchange model, spins are exchanged by the exchange interaction between two electrons. Our analysis with simple spin functions demonstrates that singlet fission is possible by spin exchange. A necessary condition for spin exchange is a variation in exchange interactions. We also adapt the spin exchange model to triplet fusion and triplet energy transfer, which often occur after singlet fission in organic solids.

[Medium high energy physics at Syracuse University

International Nuclear Information System (INIS)

Souder, P.A.

1991-10-01

This report discusses: Polarized muonic atoms; spin-dependent structure functions of the neutron; parity violation in the scattering of polarized electrons; tensor polarization in elastic eD scattering; and, hyperfine structure of muonium

Two-photon spin generation and detection

International Nuclear Information System (INIS)

Miah, M Idrish

2009-01-01

A time- and polarization-resolved two-photon pump-probe investigation is performed in lightly doped GaAs. We generate spin-polarized electrons in bulk GaAs at various temperatures using right-circularly polarized two-photon excitation and detect them by probing the spin-dependent transmission of the sample. The spin polarization (P) of conduction band electrons, as measured using probe pulses with the same (right) and opposite (left) circular polarization, is measured in dependences of pump-probe delay (Δt), lattice temperature (T L ), doping density (n) as well as of the excess photon energy ΔE 2ω = ℎ2ω - E g , where E g is the band gap energy. P is found to be decayed with Δt and enhanced with the decrease in T L or the increase in n. It is also found that P decreases with the increase in ΔE 2ω and depolarizes rapidly for ΔE 2ω > ΔE SO , where ΔE SO is the spin-orbit splitting energy. The results demonstrate that due to a much longer absorption depth highly polarized spins can be generated optically by two-photon pumping of bulk semiconductors.

The spin-spin effect in the total neutron cross section of polarized neutrons on polarized 165Ho

International Nuclear Information System (INIS)

Fasoli, U.; Galeazzi, G.; Pavan, P.; Toniolo, D.; Zago, G.; Zannoni, R.

1978-01-01

The spin-spin effect in the total neutron cross section of polarized neutrons on polarized 165 Ho has been measured in the energy interval 0.4 to 2.5 MeV, in perpendicular geometry. The results are consistent with zero effect. The spin-spin cross section sigmasub(ss) has been theoretically evaluated by a non-adiabatic coupled-channel calculation. From the comparison between the experimental and theoretical results a value Vsub(ss) = 9+-77 keV for the strength of the spin-spin potential has been obtained. Compound-nucleus effects do not seem to be relevant. (Auth.)

Spin physics at intermediate energies

International Nuclear Information System (INIS)

Burkert, V.

1986-01-01

In this session a total of 25 contributed papers were presented studying a broad range of spin effects in nucleons and nuclei using electromagnetic (electrons and photons) and hadronic (pions and nucleons) probes. The status of the theory was characterized by its almost total absence. Only one theoretical contribution was presented at this session. Those experiments examining electromagnetic-, electroweak- and weak-strong interactions were emphasized

Driving spin transition at interface: Role of adsorption configurations

Science.gov (United States)

Zhang, Yachao

2018-01-01

A clear insight into the electrical manipulation of molecular spins at interface is crucial to the design of molecule-based spintronic devices. Here we report on the electrically driven spin transition in manganocene physisorbed on a metallic surface in two different adsorption configurations predicted by ab initio techniques, including a Hubbard-U correction at the manganese site and accounting for the long-range van der Waals interactions. We show that the application of an electric field at the interface induces a high-spin to low-spin transition in the flat-lying manganocene, while it could hardly alter the high-spin ground state of the standing-up molecule. This phenomenon cannot be explained by either the molecule-metal charge transfer or the local electron correlation effects. We demonstrate a linear dependence of the intra-molecular spin-state splitting on the energy difference between crystal-field splitting and on-site Coulomb repulsion. After considering the molecule-surface binding energy shifts upon spin transition, we reproduce the obtained spin-state energetics. We find that the configuration-dependent responses of the spin-transition originate from the binding energy shifts instead of the variation of the local ligand field. Through these analyses, we obtain an intuitive understanding of the effects of molecule-surface contact on spin-crossover under electrical bias.

Technology spin-offs generation – a multicase study

Directory of Open Access Journals (Sweden)

Jonas Mendes Constante

2014-05-01

Full Text Available The objective of this study is to understand how small businesses can innovate through the generation of technological spin-offs, identifying motivations, influences and barriers to achieving this phenomenon. Through a qualitative and exploratory study, we analyzed four cases of technological spin-offs in Santa Catarina State. We collected data through field observations, historical data and semi-structured interviews. The main reasons found for spin-offs creation were: diversification and to complement the value chain of the parent company and to ensure greater focus for a specific technology. The main barrier was lack of capital. Government initiatives to support the creation of new businesses, coupled with the organizational culture open to entrepreneurship and investment in R&D, contributed to the development of spin-offs analyzed. This work contributes to the understanding that small and medium-sized technology-based companies are a source of technological spin-offs and can benefit from the occurrence of this process.

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

Semiclassical delta self-energy

International Nuclear Information System (INIS)

Voutier, E.

1992-01-01

We present a semiclassical approach in the Δ self-energy. We show that the in-medium corrections of the Δ width issued from the Pauli blocking and the coupling to the 2N-1h continuum are in good agreement with the previous approaches and particularly with the quantum Δ-h model even for light nuclei. We separate out the different sources of the imaginary part of the self-energy. The predominant corrections come from two antagonistic origins: The Pauli blocking and the contribution to the two-nucleon emission channel, the latter being model dependent. We further show that the non-diagonal spin matrix elements of the self-energy, generated by its tensor component, are mostly due to the Pauli blocking. (orig.)

Spin physics at BNL

International Nuclear Information System (INIS)

Lowenstein, D.I.

1985-01-01

Spin Physics at the Alternating Gradient Synchrotron (AGS) of Brookhaven National Laboratory is the most recent of new capabilities being explored at this facility. During the summer of 1984 the AGS accelerated beams of polarized protons to 16.5 GeV/c at 40% polarization to two experiments (E782, E785). These experiments; single spin asymmetry in inclusive polarized pp interactions; and spin-spin effects in polarized pp elastic scattering, operated at the highest polarized proton energy ever achieved by any accelerator in the world. These experiments are reviewed after the complementary spin physics program with unpolarized protons, and the future possibilities with a booster injector for the AGS and the secondary benefits of a Relativisitic Heavy Ion Collider (RHIC), are placed within the context of the present physics program

Spin flip at unelastic scattering of protons with energy near 6 NeV o 50Cr and 52Cr nuclei

International Nuclear Information System (INIS)

Andronov, Yu.F.; Chubinskij, O.V.; Vinogradov, L.I.; Ehl'-Ashri, F.I.; Gustova, L.V.

1978-01-01

Angular S(Q) and energy S(E) dependences spin flip probability S were studied in inelastic scattering of protons with excitation of the 2 1 + states of 50 Cr (Q=-0.782 MeV) and 52 Cr (Q=-1.434 MeV) energy range from 5.6 to 5.95 MeV. In particular, it is elucidated how strongly the behaviour of the spin flip probability depends upon the energy and angle of scattering at Esub(p) approximately 6 MeV for 50 Cr and 52 Cr. Thereby some additional information on specific features of the mechanism of inelastic sccattering by th nuclei is obtained. Measurements were carried out simultaneously in two proton detection channels at scattering angles differing by 30 deg. For targets use was made of self-sustaining enriched foils (87% 50 Cr and 99% 52 Cr). The angular and energy dependences of the spin flip probabilities for 50 Cr and 52 Cr are shown to be rather different: for 52 Cr has a relatively slight energy dependence in the range of a resonance observed in the excitation function; for 50 Cr the behaviour of S(E) undergoes sharp changes. The experimetnal values of S(Q) for sup(50, 52)Cr differ rather strongly from the calculations made on the statistical model and depend considerably upon the scattering angle

Spin caloritronics, origin and outlook

International Nuclear Information System (INIS)

Yu, Haiming; Brechet, Sylvain D.; Ansermet, Jean-Philippe

2017-01-01

Spin caloritronics refers to research efforts in spintronics when a heat current plays a role. In this review, we start out by reviewing the predictions that can be drawn from the thermodynamics of irreversible processes. This serves as a conceptual framework in which to analyze the interplay of charge, spin and heat transport. This formalism predicts tensorial relations between vectorial quantities such as currents and gradients of chemical potentials or of temperature. Transverse effects such as the Nernst or Hall effects are predicted on the basis that these tensors can include an anti-symmetric contribution, which can be written with a vectorial cross-product. The local symmetry of the system may determine the direction of the vector defining such transverse effects, such as the surface of an isotropic medium. By including magnetization as state field in the thermodynamic description, spin currents appear naturally from the continuity equation for the magnetization, and dissipative spin torques are derived, which are charge-driven or heat-driven. Thermodynamics does not give the strength of these effects, but may provide relationships between them. Based on this framework, the review proceeds by showing how these effects have been observed in various systems. Spintronics has become a vast field of research, and the experiments highlighted in this review pertain only to heat effects on transport and magnetization dynamics, such as magneto-thermoelectric power, or the spin-dependence of the Seebeck effect, the spin-dependence of the Peltier effect, the spin Seebeck effect, the magnetic Seebeck effect, or the Nernst effect. The review concludes by pointing out predicted effects that are yet to be verified experimentally, and in what novel materials the standard thermal spin effects could be investigated. - Highlights: • Thermodynamic description of transport: three-current model. • Magneto-thermoelectric power and spin-dependent Peltier effects. • Thermal

Spin caloritronics, origin and outlook

Energy Technology Data Exchange (ETDEWEB)

Yu, Haiming, E-mail: haiming.yu@buaa.edu.cn [Fert Beijing Institute, School of Electronic and Information Engineering, BDBC, Beihang University (China); Brechet, Sylvain D. [Institute of Physics, station 3, Ecole Polytechnique Fédérale de Lausanne, 1015 Lausanne-EPFL (Switzerland); Ansermet, Jean-Philippe, E-mail: jean-philippe.ansermet@epfl.ch [Institute of Physics, station 3, Ecole Polytechnique Fédérale de Lausanne, 1015 Lausanne-EPFL (Switzerland)

2017-03-03

Spin caloritronics refers to research efforts in spintronics when a heat current plays a role. In this review, we start out by reviewing the predictions that can be drawn from the thermodynamics of irreversible processes. This serves as a conceptual framework in which to analyze the interplay of charge, spin and heat transport. This formalism predicts tensorial relations between vectorial quantities such as currents and gradients of chemical potentials or of temperature. Transverse effects such as the Nernst or Hall effects are predicted on the basis that these tensors can include an anti-symmetric contribution, which can be written with a vectorial cross-product. The local symmetry of the system may determine the direction of the vector defining such transverse effects, such as the surface of an isotropic medium. By including magnetization as state field in the thermodynamic description, spin currents appear naturally from the continuity equation for the magnetization, and dissipative spin torques are derived, which are charge-driven or heat-driven. Thermodynamics does not give the strength of these effects, but may provide relationships between them. Based on this framework, the review proceeds by showing how these effects have been observed in various systems. Spintronics has become a vast field of research, and the experiments highlighted in this review pertain only to heat effects on transport and magnetization dynamics, such as magneto-thermoelectric power, or the spin-dependence of the Seebeck effect, the spin-dependence of the Peltier effect, the spin Seebeck effect, the magnetic Seebeck effect, or the Nernst effect. The review concludes by pointing out predicted effects that are yet to be verified experimentally, and in what novel materials the standard thermal spin effects could be investigated. - Highlights: • Thermodynamic description of transport: three-current model. • Magneto-thermoelectric power and spin-dependent Peltier effects. • Thermal

The effect of spin in swing bowling in cricket: model trajectories for spin alone

Science.gov (United States)

Robinson, Garry; Robinson, Ian

2015-02-01

In ‘swing’ bowling, as employed by fast and fast-medium bowlers in cricket, back-spin along the line of the seam is normally applied in order to keep the seam vertical and to provide stability against ‘wobble’ of the seam. Whilst spin is normally thought of as primarily being the slow bowler's domain, the spin applied by the swing bowler has the side-effect of generating a lift or Magnus force. This force, depending on the orientation of the seam and hence that of the back-spin, can have a side-ways component as well as the expected vertical ‘lift’ component. The effect of the spin itself, in influencing the trajectory of the fast bowler's delivery, is normally not considered, presumably being thought of as negligible. The purpose of this paper is to investigate, using calculated model trajectories, the amount of side-ways movement due to the spin and to see how this predicted movement compares with the total observed side-ways movement. The size of the vertical lift component is also estimated. It is found that, although the spin is an essential part of the successful swing bowler's delivery, the amount of side-ways movement due to the spin itself amounts to a few centimetres or so, and is therefore small, but perhaps not negligible, compared to the total amount of side-ways movement observed. The spin does, however, provide a considerable amount of lift compared to the equivalent delivery bowled without spin, altering the point of pitching by up to 3 m, a very large amount indeed. Thus, for example, bowling a ball with the seam pointing directly down the pitch and not designed to swing side-ways at all, but with the amount of back-spin varied, could provide a very powerful additional weapon in the fast bowler's arsenal. So-called ‘sling bowlers’, who use a very low arm action, can take advantage of spin since effectively they can apply side-spin to the ball, giving rise to a large side-ways movement, ˜ 20{}^\\circ cm or more, which certainly is

Spin dynamics of electron beams in circular accelerators

International Nuclear Information System (INIS)

Boldt, Oliver

2014-04-01

Experiments using high energy beams of spin polarized, charged particles still prove to be very helpful in disclosing a deeper understanding of the fundamental structure of matter. An important aspect is to control the beam properties, such as brilliance, intensity, energy, and degree of spin polarization. In this context, the present studies show various numerical calculations of the spin dynamics of high energy electron beams in circular accelerators. Special attention has to be paid to the emission of synchrotron radiation, that occurs when deflecting charged particles on circular orbits. In the presence of the fluctuation of the kinetic energy due to the photon emission, each electron spin moves non-deterministically. This stochastic effect commonly slows down the speed of all numeric estimations. However, the shown simulations cover - using appropriate approximations - trackings for the motion of thousands of electron spins for up to thousands of turns. Those calculations are validated and complemented by empirical investigations at the electron stretcher facility ELSA of the University of Bonn. They can largely be extended to other boundary conditions and thus, can be consulted for new accelerator layouts.

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.)

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

International Nuclear Information System (INIS)

Burkardt, M.; Nowak, W.D.

2009-08-01

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 is reviewed and an outlook for the future is offered. (orig.)

Electron--noble-gas spin-flip scattering at low energy

International Nuclear Information System (INIS)

Walker, T.G.; Bonin, K.; Happer, W.

1987-01-01

The spin-exchange rates and spin-relaxation rates for thermal electrons colliding with noble-gas atoms are calculated using the orthogonalized-plane-wave approximation and via partial-wave analysis. The two techniques give similar results and are in order-of-magnitude agreement with the experimental rate in Ar

Technology spin-offs from the magnetic fusion energy program

International Nuclear Information System (INIS)

1982-05-01

A description is given of 138 possible spin-offs from the magnetic fusion program. The spin-offs cover the following areas: (1) superconducting magnets, (2) materials technology, (3) vacuum systems, (4) high frequency and high power rf, (5) electronics, (6) plasma diagnostics, (7) computers, and (8) particle beams

Fiscal 1999 survey report on long-term energy technological strategies and the like. Long-term energy technological strategy survey (Medium-term energy technological strategy survey); 1999 nendo choki energy gijutsu senryaku nado ni kansuru chosa hokokusho. Choki energy gijutsu senryaku chosa (chuki energy gijutsu senryaku chosa)

Energy Technology Data Exchange (ETDEWEB)

NONE

2000-03-01

Energy strategies to be implemented under the New Sunshine Program by around 2010 have been compiled, with nation's industrial technological strategies, long-term energy outlook, and the like taken into consideration. The present survey aims to work out medium-term energy technological strategies. In Chapter 2, by conducting studies on the state of energy strategies in the national industry technological strategies as primarily compiled, long-term energy supply and demand outlook, and the history so far of the New Sunshine Program, and social conditions surrounding energy/environmental technologies and energy conditions are arranged in order and then analyzed with a view to deriving social needs. In Chapter 3, in view of the derived social needs, medium-term energy technological strategies are broken down into strategic target details, based on the important regions and major and minor strategic targets of the national industry technological strategies. In Chapter 4, medium-term energy technological strategies are worked out. In Chapter 5, 'basic ideas,' 'measures for promoting technology development,' 'return of the fruits to society' are mentioned as the methods of realizing the strategies. In Chapter 6, surveys and researches are summarized, and future development is predicted. (NEDO)

Spin and chirality effects in antler-topology processes at high energy e{sup +}e{sup -} colliders

Energy Technology Data Exchange (ETDEWEB)

Choi, S. Y. [Department of Physics, Chonbuk National University, 561-756, Jeonbuk (Korea, Republic of); Department of Physics and Astronomy, Pittsburgh Particle physics, Astrophysics, and Cosmology Center, University of Pittsburgh, 15260, Pittsburgh, PA (United States); Christensen, N. D. [Department of Physics, Illinois State University, 61790, Normal, IL (United States); Salmon, D.; Wang, X., E-mail: xiw77@pitt.edu [Department of Physics and Astronomy, Pittsburgh Particle physics, Astrophysics, and Cosmology Center, University of Pittsburgh, 15260, Pittsburgh, PA (United States)

2015-10-06

We perform a model-independent investigation of spin and chirality correlation effects in the antler-topology processes e{sup +}e{sup -}→P{sup +}P{sup -}→(ℓ{sup +}D{sup 0})(ℓ{sup -}D{sup -bar0}) at high-energy e{sup +}e{sup -} colliders with polarized beams. Generally the production process e{sup +}e{sup -}→P{sup +}P{sup -} can occur not only through the s-channel exchange of vector bosons, V{sup 0}, including the neutral Standard Model (SM) gauge bosons, γ and Z, but also through the s- and t-channel exchanges of new neutral states, S{sup 0} and T{sup 0}, and the u-channel exchange of new doubly charged states, U{sup --}. The general set of (non-chiral) three-point couplings of the new particles and leptons allowed in a renormalizable quantum field theory is considered. The general spin and chirality analysis is based on the threshold behavior of the excitation curves for P{sup +}P{sup -} pair production in e{sup +}e{sup -} collisions with longitudinal- and transverse-polarized beams, the angular distributions in the production process and also the production-decay angular correlations. In the first step, we present the observables in the helicity formalism. Subsequently, we show how a set of observables can be designed for determining the spins and chiral structures of the new particles without any model assumptions. Finally, taking into account a typical set of approximately chiral invariant scenarios, we demonstrate how the spin and chirality effects can be probed experimentally at a high-energy e{sup +}e{sup -} collider.

Isoscalar spin response in 40Ca and 12C

International Nuclear Information System (INIS)

Tomasi-Gustafsson, E.; Morlet, M.; Bimbot, L.; Guillot, J.; Jourdan, F.; Langevin-Joliot, H.; Marty, N.; Rosier, L.; Van de Wiele, J.; Willis, A.; Johnson, B.N.; Glashausser, C.; Djalali, C.

1994-01-01

A method founded on the measure of an approximated spin-flip probability, in the inelastic diffusion (d,d') at 400 MeV (incident energy) has been applied to the research of isoscalar spin strengths in calcium 40 and carbon 12. In calcium 40 the spin excitations have been revealed towards an excitation energy of 9 MeV and in the continuum a strength concentration appears about 15 MeV. In carbon 12 spin structures appear up to an excitation energy of 30 MeV; beyond 35 MeV the isoscalar spin response, as in calcium 40, is compatible with the expected value for a Fermi gas of particles without interactions. Microscopic calculations DWIA are in good agreement with the data of carbon 12. (O.L.). 30 refs., 5 figs

Central Arkansas Energy Project. Coal to medium-Btu gas

Science.gov (United States)

1982-05-01

The Central Arkansas Energy Project has as its objective the conversion of coal in a central location to a more readily usable energy source, medium Btu gas (MBG), for use at dispersed locations as fuel for power production and steam generation, or as a feedstock for chemical processing. The project elements consist of a gasification facility to produce MBG from coal, a pipeline to supply the MBG to the dispersed sites. The end of line users investigated were the repowering or refueling of an existing Arkansas Power and Light Co. Generating station, an ammonia plant, and a combined cycle cogeneration facility for the production of steam and electricity. Preliminary design of the gasification plant including process engineering design bases, process flow diagrams, utility requirements, system description, project engineering design, equipment specifications, plot plan and section plot plans, preliminary piping and instrument diagrams, and facilities requirements. Financial analyses and sensitivities are determined. Design and construction schedules and manpower loadings are developed. It is concluded that the project is technically feasible, but the financial soundness is difficult to project due to uncertainty in energy markets of competing fuels.

Spin modes

International Nuclear Information System (INIS)

Gaarde, C.

1985-01-01

An analysis of spectra of (p,n) reactions showed that they were very selective in exciting spin modes. Charge exchange reactions at intermediate energies give important new understanding of the M1-type of excitations and of the spin structure of continuum p spectra in general. In this paper, the author discusses three charge exchange reactions: (p,n); ( 3 H,t); and (d,2p) at several targets. Low-lying states and the Δ region are discussed separately. Finally, the charge exchange reaction with heavy ion beams is briefly discussed. (G.J.P./Auth.)

Spin-polarized hydrogen, deuterium, and tritium : I

International Nuclear Information System (INIS)

Haugen, M.; Ostgaard, E.

1989-01-01

The ground-state energy of spin-polarized hydrogen, deuterium and tritium is calculated by means of a modified variational lowest order constrained-variation method, and the calculations are done for five different two-body potentials. Spin-polarized H is not self-bound according to our theoretical results for the ground-state binding energy. For spin-polarized D, however, we obtain theoretical results for the ground-state binding energy per particle from -0.4 K at an equilibrium particle density of 0.25 σ -3 or a molar volume of 121 cm 3 /mol to +0.32 K at an equilibrium particle density of 0.21 σ -3 or a molar volume of 142 cm 3 /mol, where σ = 3.69 A (1A = 10 -10 m). It is, therefore, not clear whether spin-polarized deuterium should be self-bound or not. For spin-polarized T, we obtain theoretical results for the ground-state binding energy per particle from -4.73 K at an equilibrium particle density of 0.41 σ -3 or a molar volume of 74 cm 3 /mol to -1.21 K at an equilibrium particle density of 0.28 σ -3 or a molar volume of 109 cm 3 /mol. (Author) 27 refs., 9 figs., tab

Excitation spectrum of Heisenberg spin ladders

International Nuclear Information System (INIS)

Barnes, T.; Dagotto, E.; Riera, J.; Swanson, E.S.

1993-01-01

Heisenberg antiferromagnetic spin ''ladders'' (two coupled spin chains) are low-dimensional magnetic systems which for S=1/2 interpolate between half-integer-spin chains, when the chains are decoupled, and effective integer-spin one-dimensional chains in the strong-coupling limit. The spin-1/2 ladder may be realized in nature by vanadyl pyrophosphate, (VO) 2 P 2 O 7 . In this paper we apply strong-coupling perturbation theory, spin-wave theory, Lanczos techniques, and a Monte Carlo method to determine the ground-state energy and the low-lying excitation spectrum of the ladder. We find evidence of a nonzero spin gap for all interchain couplings J perpendicular >0. A band of spin-triplet excitations above the gap is also analyzed. These excitations are unusual for an antiferromagnet, since their long-wavelength dispersion relation behaves as (k-k 0 ) 2 (in the strong-coupling limit J perpendicular much-gt J, where J is the in-chain antiferromagnetic coupling). Their band is folded, with a minimum energy at k 0 =π, and a maximum between k 1 =π/2 (for J perpendicular =0) and 0 (for J perpendicular =∞). We also give numerical results for the dynamical structure factor S(q,ω), which can be determined in neutron scattering experiments. Finally, possible experimental techniques for studying the excitation spectrum are discussed

Spin Transport in Mesoscopic Superconducting-Ferromagnetic Hybrid Conductor

Directory of Open Access Journals (Sweden)

Zein W. A.

2008-01-01

Full Text Available The spin polarization and the corresponding tunneling magnetoresistance (TMR for a hybrid ferromagnetic / superconductor junction are calculated. The results show that these parameters are strongly depends on the exchange field energy and the bias voltage. The dependence of the polarization on the angle of precession is due to the spin flip through tunneling process. Our results could be interpreted as due to spin imbalance of carriers resulting in suppression of gap energy of the superconductor. The present investigation is valuable for manufacturing magnetic recording devices and nonvolatile memories which imply a very high spin coherent transport for such junction.

Spin Transport in Mesoscopic Superconducting-Ferromagnetic Hybrid Conductor

Directory of Open Access Journals (Sweden)

Zein W. A.

2008-01-01

Full Text Available The spin polarization and the corresponding tunneling magnetoresistance (TMR for a hybrid ferromagnetic/superconductor junction are calculated. The results show that these parameters are strongly depends on the exchange field energy and the bias voltage. The dependence of the polarization on the angle of precession is due to the spin flip through tunneling process. Our results could be interpreted as due to spin imbalance of carriers resulting in suppression of gap energy of the superconductor. The present investigation is valuable for manufacturing magnetic recording devices and nonvolatile memories which imply a very high spin coherent transport for such junction.

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.)

Design and commissioning of an aberration-corrected ultrafast spin-polarized low energy electron microscope with multiple electron sources.

Science.gov (United States)

Wan, Weishi; Yu, Lei; Zhu, Lin; Yang, Xiaodong; Wei, Zheng; Liu, Jefferson Zhe; Feng, Jun; Kunze, Kai; Schaff, Oliver; Tromp, Ruud; Tang, Wen-Xin

2017-03-01

We describe the design and commissioning of a novel aberration-corrected low energy electron microscope (AC-LEEM). A third magnetic prism array (MPA) is added to the standard AC-LEEM with two prism arrays, allowing the incorporation of an ultrafast spin-polarized electron source alongside the standard cold field emission electron source, without degrading spatial resolution. The high degree of symmetries of the AC-LEEM are utilized while we design the electron optics of the ultrafast spin-polarized electron source, so as to minimize the deleterious effect of time broadening, while maintaining full control of electron spin. A spatial resolution of 2nm and temporal resolution of 10ps (ps) are expected in the future time resolved aberration-corrected spin-polarized LEEM (TR-AC-SPLEEM). The commissioning of the three-prism AC-LEEM has been successfully finished with the cold field emission source, with a spatial resolution below 2nm. Copyright © 2017 Elsevier B.V. All rights reserved.

Calculation of nuclear spin-spin coupling constants using frozen density embedding

Energy Technology Data Exchange (ETDEWEB)

Götz, Andreas W., E-mail: agoetz@sdsc.edu [San Diego Supercomputer Center, University of California San Diego, 9500 Gilman Dr MC 0505, La Jolla, California 92093-0505 (United States); Autschbach, Jochen [Department of Chemistry, University at Buffalo, State University of New York, Buffalo, New York 14260-3000 (United States); Visscher, Lucas, E-mail: visscher@chem.vu.nl [Amsterdam Center for Multiscale Modeling (ACMM), VU University Amsterdam, Theoretical Chemistry, De Boelelaan 1083, 1081 HV Amsterdam (Netherlands)

2014-03-14

We present a method for a subsystem-based calculation of indirect nuclear spin-spin coupling tensors within the framework of current-spin-density-functional theory. Our approach is based on the frozen-density embedding scheme within density-functional theory and extends a previously reported subsystem-based approach for the calculation of nuclear magnetic resonance shielding tensors to magnetic fields which couple not only to orbital but also spin degrees of freedom. This leads to a formulation in which the electron density, the induced paramagnetic current, and the induced spin-magnetization density are calculated separately for the individual subsystems. This is particularly useful for the inclusion of environmental effects in the calculation of nuclear spin-spin coupling constants. Neglecting the induced paramagnetic current and spin-magnetization density in the environment due to the magnetic moments of the coupled nuclei leads to a very efficient method in which the computationally expensive response calculation has to be performed only for the subsystem of interest. We show that this approach leads to very good results for the calculation of solvent-induced shifts of nuclear spin-spin coupling constants in hydrogen-bonded systems. Also for systems with stronger interactions, frozen-density embedding performs remarkably well, given the approximate nature of currently available functionals for the non-additive kinetic energy. As an example we show results for methylmercury halides which exhibit an exceptionally large shift of the one-bond coupling constants between {sup 199}Hg and {sup 13}C upon coordination of dimethylsulfoxide solvent molecules.

Absorbed dose determination in water in medium energy x-ray beam

International Nuclear Information System (INIS)

Nisevic, G.; Spasic-Jokic, V.

1998-01-01

Absorbed dose determination in water phantom in medium energy X-ray beam, according to IAEA recommendations is given. This method is applied on Radiotherapy department of Military Academy Hospital in Belgrade. Reference points of measurements are on depth of 5 cm and 2 cm as it recommended in ref. Experimental results are shown in aim to introduce new dosimetric concept based on air kerma calibration factor recommended for application in our radiotherapy centers (author)

The Role of Self-Interaction Corrections, Vibrations, and Spin-Orbit in Determining the Ground Spin State in a Simple Heme

Directory of Open Access Journals (Sweden)

Der-you Kao

2017-10-01

Full Text Available Without self-interaction corrections or the use of hybrid functionals, approximations to the density-functional theory (DFT often favor intermediate spin systems over high-spin systems. In this paper, we apply the recently proposed Fermi–Löwdin-orbital self-interaction corrected density functional formalism to a simple tetra-coordinated Fe(II-porphyrin molecule and show that the energetic orderings of the S = 1 and S = 2 spin states are changed qualitatively relative to the results of Generalized Gradient Approximation (developed by Perdew, Burke, and Ernzerhof, PBE-GGA and Local Density Approximation (developed by Perdew and Wang, PW92-LDA. Because the energetics, associated with changes in total spin, are small, we have also calculated the second-order spin–orbit energies and the zero-point vibrational energies to determine whether such corrections could be important in metal-substituted porphins. Our results find that the size of the spin–orbit and vibrational corrections to the energy orderings are small compared to the changes due to the self-interaction correction. Spin dependencies in the Infrared (IR/Raman spectra and the zero-field splittings are provided as a possible means for identifying the spin in porphyrins containing Fe(II.

Recent results in the development of a global medium-energy nucleon-nucleus optical-model potential

International Nuclear Information System (INIS)

Madland, D.G.

1988-02-01

Initial results are presented for the determination of a global medium-energy nucleon-nucleus phenomenological optical-model potential using a relativistic Schroedinger representation. The starting point for this work is the global phenomenological optical-model potential of Schwandt /ital et al./, which is based on measured elastic scattering cross sections and analyzing power for polarized protons ranging from 80 to 180 MeV. This potential is optimally modified to reproduce experimental proton reaction cross sections as a function of energy, while allowing only minimal deterioration in the fits to the elastic cross sections and analyzing powers. Further modifications in the absorptive potential were found necessary to extrapolate the modified potential to higher energies. The final potential is converted to a neutron-nucleus potential by use of standard Lane model assumptions and by accounting approximately for the Coulomb correction. Comparisons of measured and calculated proton reaction and neutron total cross sections are presented for 27 Al, 56 Fe, and 208 Pb. Medium-energy optical-model potentials for complex projectiles are briefly discussed in an appendix. 7 refs., 20 figs

Monte Carlo investigations on surface elastic energy of spin-crossover solids: Direct access to image pressure and the Eshelby constant

Science.gov (United States)

Boukheddaden, Kamel

2013-10-01

We present theoretical investigations on surface elastic energy in spin-crossover (SC) solids studied in the frame of a microscopic elastic model, coupling spin, and lattice deformations. Although surface energy plays a crucial role in driving the SC transition, specific quantitative investigations on its effect have been neglected in most of the recent theoretical works based on atomistic descriptions of the SC transitions, resolved by Monte Carlo or by molecular dynamics simulations. Here, we perform a quantitative study of the surface energy resulting from an inserted high-spin (HS) domain in a low-spin (LS) lattice. This situation may be produced experimentally in SC solids, at low temperature, through a photoexcitation by a single pulse laser shot. We demonstrate that the surface energy depends on the ratio between the local molecular volume misfit (between the LS and HS sites) δυ and the lattice volume V, such as Esurf˜δυ2/V for the HS atom at the center of lattice, while it is Esurf˜δυ2/L (L is the length of the lattice) in the case of the HS atom located on the edge of the lattice. We then derived the image pressure (negative in the case of embedded dilatation centers) through the work of the free surface atoms and evaluated the Eshelby constant, which was found equal to γ˜1.90, in very good agreement with the available data of literature. Energetic configuration diagrams in the homogeneous (HS and LS) and heterogeneous (coexistence of HS and LS) are calculated, from which estimations of the macroscopic bulk modulus were deduced.

Energy relaxation between low lying tunnel split spin-states of the single molecule magnet Ni4

Science.gov (United States)

de Loubens, G.; Chaves-O'Flynn, G. D.; Kent, A. D.; Ramsey, C.; Del Barco, E.; Beedle, C.; Hendrickson, D. N.

2007-03-01

We have developed integrated magnetic sensors to study quantum tunneling of magnetization (QTM) in single molecule magnet (SMMs) single crystals. These sensors incorporate a microstrip resonator (30 GHz) and a micro-Hall effect magnetometer. They have been used to investigate the relaxation rates between the 2 lowest lying tunnel split spin-states of the SMM Ni4 (S=4). EPR spectroscopy at 30 GHz and 0.4 K and concurrent magnetization measurements of several Ni4 single crystals are presented. EPR enables measurement of the energy splitting between the 2 lowest lying superposition states as a function of the longitudinal and transverse fields. The energy relaxation rate is determined in two ways. First, in cw microwave experiments the change in spin-population together with the microwave absorption directly gives the relaxation time from energy conservation in steady-state. Second, direct time-resolved measurements of the magnetization with pulsed microwave radiation have been performed. The relaxation time is found to vary by several orders of magnitude in different crystals, from a few seconds down to smaller than 100 μs. We discuss this and the form of the relaxation found for different crystals and pulse conditions.

Low Energy Spectrum of Proximate Kitaev Spin Liquid α -RuCl3 by Terahertz Spectroscopy

Science.gov (United States)

Little, Arielle; Wu, Liang; Kelley, Paige; Banerjee, Arnab; Bridges, Craig; Yan, Jiaqiang; Nagler, Stephen; Mandrus, David; Orenstein, Joseph

A Quantum Spin Liquid (QSL) is an ultra-quantum state of matter with no ordered ground state. Recently, a route to a QSL identified by Kitaev has received a great deal of attention. The compound α -RuCl3, in which Ru atoms form a honeycomb lattice, has been shown to possess Kitaev exchange interactions, although a smaller Heisenberg interaction exists and leads to a zig-zag antiferromagnetic state below 7 K. Because of proximity to the exactly-solvable Kitaev spin-liquid model, this material is considered a potential host for Majorana-like modes. In this work, we use time-domain terahertz (THz) Spectroscopy to probe the low-energy excitations of α -RuCl3. We observe the emergence of a sharp magnetic spin-wave absorption peak below the AFM ordering temperature at 7 K on top of a broad continuum that persists up to room temperature. Additionally we report the polarization dependence of the THz absorption, which reveals optical birefringence, indicating the presence of large monoclinic domains.

Two-photon spin generation and detection

Energy Technology Data Exchange (ETDEWEB)

Miah, M Idrish, E-mail: m.miah@griffith.edu.a [Nanoscale Science and Technology Centre, Griffith University, Nathan, Brisbane, QLD 4111 (Australia)

2009-02-21

A time- and polarization-resolved two-photon pump-probe investigation is performed in lightly doped GaAs. We generate spin-polarized electrons in bulk GaAs at various temperatures using right-circularly polarized two-photon excitation and detect them by probing the spin-dependent transmission of the sample. The spin polarization (P) of conduction band electrons, as measured using probe pulses with the same (right) and opposite (left) circular polarization, is measured in dependences of pump-probe delay ({Delta}t), lattice temperature (T{sub L}), doping density (n) as well as of the excess photon energy {Delta}E{sub 2{omega}}= {h_bar}2{omega} - E{sub g}, where E{sub g} is the band gap energy. P is found to be decayed with {Delta}t and enhanced with the decrease in T{sub L} or the increase in n. It is also found that P decreases with the increase in {Delta}E{sub 2{omega}}and depolarizes rapidly for {Delta}E{sub 2{omega}}> {Delta}E{sub SO}, where {Delta}E{sub SO} is the spin-orbit splitting energy. The results demonstrate that due to a much longer absorption depth highly polarized spins can be generated optically by two-photon pumping of bulk semiconductors.

Probing medium-induced jet splitting and energy loss in heavy-ion collisions

Science.gov (United States)

Chang, Ning-Bo; Cao, Shanshan; Qin, Guang-You

2018-06-01

The nuclear modification of jet splitting in relativistic heavy-ion collisions at RHIC and the LHC energies is studied based on the higher twist formalism. Assuming coherent energy loss for the two splitted subjets, a non-monotonic jet energy dependence is found for the nuclear modification of jet splitting function: strongest modification at intermediate jet energies whereas weaker modification for larger or smaller jet energies. Combined with the smaller size and lower density of the QGP medium at RHIC than at the LHC, this helps to understand the groomed jet measurements from CMS and STAR Collaborations: strong modification of the momentum sharing zg distribution at the LHC and no obvious modification of zg distribution at RHIC. In addition, the observed nuclear modification pattern of the groomed jet zg distribution cannot be explained solely by independent energy loss of the two subjets. Our result may be tested in future measurements of groomed jets with lower jet energies at the LHC and larger jet energies at RHIC, for different angular separations between the two subjets.

Global potential energy surface of ground state singlet spin O4

Science.gov (United States)

Mankodi, Tapan K.; Bhandarkar, Upendra V.; Puranik, Bhalchandra P.

2018-02-01

A new global potential energy for the singlet spin state O4 system is reported using CASPT2/aug-cc-pVTZ ab initio calculations. The geometries for the six-dimensional surface are constructed using a novel point generation scheme that employs randomly generated configurations based on the beta distribution. The advantage of this scheme is apparent in the reduction of the number of required geometries for a reasonably accurate potential energy surface (PES) and the consequent decrease in the overall computational effort. The reported surface matches well with the recently published singlet surface by Paukku et al. [J. Chem. Phys. 147, 034301 (2017)]. In addition to the O4 PES, the ground state N4 PES is also constructed using the point generation scheme and compared with the existing PES [Y. Paukku et al., J. Chem. Phys. 139, 044309 (2013)]. The singlet surface is constructed with the aim of studying high energy O2-O2 collisions and predicting collision induced dissociation cross section to be used in simulating non-equilibrium aerothermodynamic flows.

X-ray diffraction study of stress relaxation in cubic boron nitride films grown with simultaneous medium-energy ion bombardment

International Nuclear Information System (INIS)

Abendroth, B.; Gago, R.; Eichhorn, F.; Moeller, W.

2004-01-01

Relaxation of the intrinsic stress of cubic boron nitride (cBN) thin films has been studied by x-ray diffraction (XRD) using synchrotron light. The stress relaxation has been attained by simultaneous medium-energy ion bombardment (2-10 keV) during magnetron sputter deposition, and was confirmed macroscopically by substrate curvature measurements. In order to investigate the stress-release mechanisms, XRD measurements were performed in in-plane and out-of-plane geometry. The analysis shows a pronounced biaxial state of compressive stress in the cBN films grown without medium-energy ion bombardment. This stress is partially released during the medium-energy ion bombardment. It is suggested that the main path for stress relaxation is the elimination of strain within the cBN grains due to annealing of interstitials

Muon spin relaxation in ferromagnets. Pt. 1

International Nuclear Information System (INIS)

Lovesey, S.W.; Karlsson, E.B.

1991-04-01

Expressions for the dipolar and hyperfine contributions to the relaxation rate of muons implanted in a ferromagnet are presented and analysed using the Heisenberg model of spin-waves including dipolar and Zeeman energies. Calculations for EuO indicate that relaxation is likely to be dominated by the hyperfine mechanism, even if the ratio of the hyperfine and dipolar coupling constants is small. The hyperfine mechanism is sensitive to the dipolar energy of the atomic spins, whereas the dipolar mechanisms depend essentially on the exchange energy. For both mechanisms there is an almost quadratic dependence on temperature, throughout much of the ordered magnetic phase, which reflects two-spin-wave difference events from the Raman-type relaxation processes. (author)

Unique spin-polarized transmission effects in a QD ring structure

Science.gov (United States)

Hedin, Eric; Joe, Yong

2010-10-01

Spintronics is an emerging field in which the spin of the electron is used for switching purposes and to communicate information. In order to obtain spin-polarized electron transmission, the Zeeman effect is employed to produce spin-split energy states in quantum dots which are embedded in the arms of a mesoscopic Aharonov-Bohm (AB) ring heterostructure. The Zeeman splitting of the QD energy levels can be induced by a parallel magnetic field, or by a perpendicular field which also produces AB-effects. The combination of these effects on the transmission resonances of the structure is studied analytically and several parameter regimes are identified which produce a high degree of spin-polarized output. Contour and line plots of the weighted spin polarization as a function of electron energy and magnetic field are presented to visualize the degree of spin-polarization. Taking advantage of these unique parameter regimes shows the potential promise of such devices for producing spin-polarized currents.

Co-generation and innovative heat storage systems in small-medium CSP plants for distributed energy production

Science.gov (United States)

Giaconia, Alberto; Montagnino, Fabio; Paredes, Filippo; Donato, Filippo; Caputo, Giampaolo; Mazzei, Domenico

2017-06-01

CSP technologies can be applied for distributed energy production, on small-medium plants (on the 1 MW scale), to satisfy the needs of local communities, buildings and districts. In this perspective, reliable, low-cost, and flexible small/medium multi-generative CSP plants should be developed. Four pilot plants have been built in four Mediterranean countries (Cyprus, Egypt, Jordan, and Italy) to demonstrate the approach. In this paper, the plant built in Italy is presented, with specific innovations applied in the linear Fresnel collector design and the Thermal Energy Storage (TES) system, based on a single the use of molten salts but specifically tailored for small scale plants.

Chiral magnetic currents with QGP medium response in heavy-ion collisions at RHIC and LHC energies

Science.gov (United States)

She, Duan; Feng, Sheng-Qin; Zhong, Yang; Yin, Zhong-Bao

2018-03-01

We calculate the electromagnetic current with a more realistic approach in the RHIC and LHC energy regions in the article. We take the partons formation time as the initial time of the magnetic field response of QGP medium. The maximum electromagnetic current and the time-integrated current are two important characteristics of the chiral magnetic effect (CME), which can characterize the intensity and duration of fluctuations of CME. We consider the finite frequency response of CME to a time-varying magnetic field, find a significant impact from QGP medium feedback, and estimate the generated electromagnetic current as a function of time, beam energy and impact parameter.

Majorana spin in magnetic atomic chain systems

Science.gov (United States)

Li, Jian; Jeon, Sangjun; Xie, Yonglong; Yazdani, Ali; Bernevig, B. Andrei

2018-03-01

In this paper, we establish that Majorana zero modes emerging from a topological band structure of a chain of magnetic atoms embedded in a superconductor can be distinguished from trivial localized zero energy states that may accidentally form in this system using spin-resolved measurements. To demonstrate this key Majorana diagnostics, we study the spin composition of magnetic impurity induced in-gap Shiba states in a superconductor using a hybrid model. By examining the spin and spectral densities in the context of the Bogoliubov-de Gennes (BdG) particle-hole symmetry, we derive a sum rule that relates the spin densities of localized Shiba states with those in the normal state without superconductivity. Extending our investigations to a ferromagnetic chain of magnetic impurities, we identify key features of the spin properties of the extended Shiba state bands, as well as those associated with a localized Majorana end mode when the effect of spin-orbit interaction is included. We then formulate a phenomenological theory for the measurement of the local spin densities with spin-polarized scanning tunneling microscopy (STM) techniques. By combining the calculated spin densities and the measurement theory, we show that spin-polarized STM measurements can reveal a sharp contrast in spin polarization between an accidental-zero-energy trivial Shiba state and a Majorana zero mode in a topological superconducting phase in atomic chains. We further confirm our results with numerical simulations that address generic parameter settings.

Spin selection at organic spinterface by anchoring group

Energy Technology Data Exchange (ETDEWEB)

Zhang, Zhao; Qiu, Shuai; Miao, Yuan-yuan; Ren, Jun-feng; Wang, Chuan-kui [School of Physics and Electronics, Shandong Normal University, Jinan 250014 (China); Hu, Gui-chao, E-mail: hgc@sdnu.edu.cn [School of Physics and Electronics, Shandong Normal University, Jinan 250014 (China); Institute of Theoretical Physics, Technische Universität Dresden, 01062 Dresden (Germany)

2017-07-01

Highlights: • The sign of interfacial spin polarization can be selected by using different anchoring groups. • A sp{sup 3}-d or sp-d hybridization may occur and induce spin polarization when the anchoring group changes. • Interfacial spin polarization depends on both the type of the outer orbital of the anchoring atom as well as its energy. - Abstract: Control of organic interfacial spin polarization is crucial in organic spintronics. Based on ab initio theory, here we proposed a spin selection at organic interface via anchoring group by adsorbing an organic molecule onto Ni(111) surface. The results demonstrate that either a positive or negative interfacial spin polarization may be obtained by choosing different anchoring groups. The orbital analysis via the projected density of states shows that the interfacial spin polarization is sensitive to the hybridization of the outer orbital of the anchoring atom as well as its energy relative to the d orbital of the ferromagnetic atom. The work indicates a feasible way to realize spin selection at the organic spinterface by anchoring group.

Spin and energy transfer between magnetic ions and free carriers in diluted-magnetic semiconductor heterostructures

Energy Technology Data Exchange (ETDEWEB)

Yakovlev, D.R. [Experimental Physics 2, University of Dortmund, 44227 Dortmund (Germany); Ioffe Physico-Technical Institute, Russian Academy of Sciences, 194021 St. Petersburg (Russian Federation); Kneip, M.; Bayer, M. [Experimental Physics 2, University of Dortmund, 44227 Dortmund (Germany); Maksimov, A.A.; Tartakovskii, I.I. [Institute of Solid State Physics, Russian Academy of Sciences, 142432 Chernogolovka (Russian Federation); Keller, D.; Ossau, W.; Molenkamp, L.W. [Physikalisches Institut der Universitaet Wuerzburg, 97074 Wuerzburg (Germany); Scherbakov, A.V.; Akimov, A.V. [Ioffe Physico-Technical Institute, Russian Academy of Sciences, 194021 St. Petersburg (Russian Federation); Waag, A. [Abteilung Halbleiterphysik, Universitaet Ulm, 89081 Ulm (Germany)

2004-03-01

In this paper we give a brief overview of our studies on dynamical processes in diluted-magnetic-semiconductor heterostructures based on (Zn,Mn)Se and (Cd,Mn)Te. Presence of free carriers is an important factor which determines the energy- and spin transfer in a coupled systems of magnetic ions, lattice (the phonon system) and carriers. We report also new data on dynamical response of magnetic ions interacting with photogenerated electron-hole plasma. (Zn,Mn)Se/(Zn,Be)Se structures with relatively high Mn content of 11% provide spin-lattice relaxation time of about 20 ns, which is considerably shorter then the characteristic times of nonequilibrium phonons ranging to 1 {mu}s. (copyright 2004 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Feasibility of a medium-size central cogenerated energy facility, energy management memorandum

Science.gov (United States)

Porter, R. W.

1982-09-01

The thermal-economic feasibility was studied of a medium-size central cogenerated energy facility designed to serve five varied industries. Generation options included one dual-fuel diesel and one gas turbine, both with waste heat boilers, and five fired boilers. Fuels included natural gas, and for the fired-boiler cases, also low-sulphur coal and municipal refuse. The fired-boiler cogeneration systems employed back-pressure steam turbines. For coal and refuse, the option of steam only without cogeneration was also assessed. The refuse-fired cases utilized modular incinerators. The options provided for a wide range of steam and electrical capacities. Deficient steam was assumed generated independently in existing equipment. Excess electrical power over that which could be displaced was assumed sold to Commonwealth Edison Company under PURPA (Public Utility Regulator Policies Act). The facility was assumed operated by a mutually owned corporation formed by the cogenerated power users. The economic analysis was predicted on currently applicable energy-investment tax credits and accelerated depreciation for a January 1985 startup date. Based on 100% equity financing, the results indicated that the best alternative was the modular-incinerator cogeneration system.

Public acceptance of fusion energy and scientific feasibility of a fusion reactor. Spin-off effects of fusion research and development

International Nuclear Information System (INIS)

Morino, Nobuyuki; Ogawa, Yuichi

1998-01-01

It is observed that new and sophisticated technologies developed through research and development in relation to magnetic confinement fusion have been transferred to other industrial and scientific fields with remarkable spin-off effects. Approximately 10 years ago, the Japan Atomic Industrial Forum (JAIF) has investigated technical transfer and spin-off effects of fusion technologies developed in Japan. The essence of the results of this investigation as well as high technologies developed in the last decade, some of which are in the early stage of technical spin-off, are described. It is additionally explained that independent technical development conducted by our country as well as by engineers themselves is important in achieving effective spin-off. An outline of scientific spin-off effects is also described, including utilization technologies of fusion reactions besides those for energy production purposes, the progress of scientific understanding in the course of fusion research, and scientific information transfer and communication with other fields. (author)

Quadratic integrand double-hybrid made spin-component-scaled

Energy Technology Data Exchange (ETDEWEB)

Brémond, Éric, E-mail: eric.bremond@iit.it; Savarese, Marika [CompuNet, Istituto Italiano di Tecnologia, via Morego 30, I-16163 Genoa (Italy); Sancho-García, Juan C.; Pérez-Jiménez, Ángel J. [Departamento de Química Física, Universidad de Alicante, E-03080 Alicante (Spain); Adamo, Carlo [CompuNet, Istituto Italiano di Tecnologia, via Morego 30, I-16163 Genoa (Italy); Chimie ParisTech, PSL Research University, CNRS, Institut de Recherche de Chimie Paris IRCP, F-75005 Paris (France); Institut Universitaire de France, 103 Boulevard Saint Michel, F-75005 Paris (France)

2016-03-28

We propose two analytical expressions aiming to rationalize the spin-component-scaled (SCS) and spin-opposite-scaled (SOS) schemes for double-hybrid exchange-correlation density-functionals. Their performances are extensively tested within the framework of the nonempirical quadratic integrand double-hybrid (QIDH) model on energetic properties included into the very large GMTKN30 benchmark database, and on structural properties of semirigid medium-sized organic compounds. The SOS variant is revealed as a less computationally demanding alternative to reach the accuracy of the original QIDH model without losing any theoretical background.

Measurement of the depolarization of the reaction 27Al(p vector,p vector.)27Al for the study of the spin-spin potential

International Nuclear Information System (INIS)

Loeh, H.

1981-01-01

For the study of the spin-spin interaction in the optical potential the depolarisation in the elastic scattering of polarized protons was measured. The double-scattering experiments were performed in the angular range 40 0 -110 0 at an incident energy of 10.35 MeV at the Erlangen QD-magnetic spectrometer. The determination of the optical model parameters independent from the spin-spin potentials was performed by the fitting of these to the observables and sigmasup(di). These were obtained from a measurement of the angular distribution of the analyzing power and the differential cross section in the 4π-scattering chamber for the reaction 27 Al(p vector,p 0 ) at the same energy. The compound contributions present at this energy, which can also influence the depolarization, were regarded by the calculation of the compound-elastic non-spin-flip respectively spin-flip subcross sections by means of the formalism of Hofmann, Richert, Tepel and Weidenmueller. Because the target nucleus 27 Al possesses in the ground state a spin I=5/2, also the possible quadrupole spin flip had to be included. This was performed by coupled-channel calculations. The respecting compound contributions and quadrupole effects corrected depolarization data could by used for the study of the spin-spin potentials by means of DWBA calculations. As result it was shown that for the description of the experimental data a spherical spin-spin potential of the strength Vsub(SS)=1.5+-0.3 MeV had to be assumed. (orig.) [de

Characteristics of persistent spin current components in a quasi-periodic Fibonacci ring with spin–orbit interactions: Prediction of spin–orbit coupling and on-site energy

International Nuclear Information System (INIS)

Patra, Moumita; Maiti, Santanu K.

2016-01-01

In the present work we investigate the behavior of all three components of persistent spin current in a quasi-periodic Fibonacci ring subjected to Rashba and Dresselhaus spin–orbit interactions. Analogous to persistent charge current in a conducting ring where electrons gain a Berry phase in presence of magnetic flux, spin Berry phase is associated during the motion of electrons in presence of a spin–orbit field which is responsible for the generation of spin current. The interplay between two spin–orbit fields along with quasi-periodic Fibonacci sequence on persistent spin current is described elaborately, and from our analysis, we can estimate the strength of any one of two spin–orbit couplings together with on-site energy, provided the other is known. - Highlights: • Determination of Rashba and Dresselhaus spin–orbit fields is discussed. • Characteristics of all three components of spin current are explored. • Possibility of estimating on-site energy is given. • Results can be generalized to any lattice models.

Characteristics of persistent spin current components in a quasi-periodic Fibonacci ring with spin–orbit interactions: Prediction of spin–orbit coupling and on-site energy

Energy Technology Data Exchange (ETDEWEB)

Patra, Moumita; Maiti, Santanu K., E-mail: santanu.maiti@isical.ac.in

2016-12-15

In the present work we investigate the behavior of all three components of persistent spin current in a quasi-periodic Fibonacci ring subjected to Rashba and Dresselhaus spin–orbit interactions. Analogous to persistent charge current in a conducting ring where electrons gain a Berry phase in presence of magnetic flux, spin Berry phase is associated during the motion of electrons in presence of a spin–orbit field which is responsible for the generation of spin current. The interplay between two spin–orbit fields along with quasi-periodic Fibonacci sequence on persistent spin current is described elaborately, and from our analysis, we can estimate the strength of any one of two spin–orbit couplings together with on-site energy, provided the other is known. - Highlights: • Determination of Rashba and Dresselhaus spin–orbit fields is discussed. • Characteristics of all three components of spin current are explored. • Possibility of estimating on-site energy is given. • Results can be generalized to any lattice models.

Medium energy hadron-nucleus scattering in the 1/N expansion formalism

International Nuclear Information System (INIS)

Kuyucak, S.; Morrison, I.

1992-01-01

The algebraic-eikonal approach to the medium energy hadron-nucleus scattering is generalized to arbitrary interactions and boson types using the 1/N expansion technique for the interacting boson model. The results are used in a comparative study of proton scattering from deformed nuclei in the sd and sdg boson models. The two models give almost identical results for a pure quadrupole interaction but widely differ when a hexadecapole interaction is included. 25 refs., 3 tabs., 7 figs

Assisted Writing in Spin Transfer Torque Magnetic Tunnel Junctions

Science.gov (United States)

Ganguly, Samiran; Ahmed, Zeeshan; Datta, Supriyo; Marinero, Ernesto E.

2015-03-01

Spin transfer torque driven MRAM devices are now in an advanced state of development, and the importance of reducing the current requirement for writing information is well recognized. Different approaches to assist the writing process have been proposed such as spin orbit torque, spin Hall effect, voltage controlled magnetic anisotropy and thermal excitation. In this work,we report on our comparative study using the Spin-Circuit Approach regarding the total energy, the switching speed and energy-delay products for different assisted writing approaches in STT-MTJ devices using PMA magnets.

Measurements of energy behaviour of spin-dependent np—observables over 1.2-3.7 GeV energy region Dubna ``Delta-Sigma'' Experiment

Science.gov (United States)

Sharov, V. I.; Anischenko, N. G.; Antonenko, V. G.; Averichev, S. A.; Azhgirey, L. S.; Bartenev, V. D.; Bazhanov, N. A.; Belyaev, A. A.; Blinov, N. A.; Borisov, N. S.; Borzakov, S. B.; Borzunov, Yu. T.; Bushuev, Yu. P.; Chernenko, L. P.; Chernykh, E. V.; Chumakov, V. F.; Dolgh, S. A.; Fedorov, A. N.; Fimushkin, V. V.; Finger, M.; Finger, M.; Golovanov, L. B.; Gurevich, G. M.; Guriev, D. K.; Janata, A.; Kirillov, A. D.; Kolomiets, V. G.; Komogorov, E. V.; Kovalenko, A. D.; Kovalev, A. I.; Krasnov, V. A.; Krstonoshich, P.; Kuzmin, E. S.; Kuzmin, N. A.; Ladygin, V. P.; Lazarev, A. B.; Lehar, F.; de Lesquen, A.; Liburg, M. Yu.; Livanov, A. N.; Lukhanin, A. A.; Maniakov, P. K.; Matafonov, V. N.; Matyushevsky, E. A.; Moroz, V. D.; Morozov, A. A.; Neganov, A. B.; Nikolaevsky, G. P.; Nomofilov, A. A.; Panteleev, Tz.; Pillpenko, Yu. K.; Pisarev, I. L.; Plis, Yu. A.; Polunin, Yu. P.; Prokofiev, A. N.; Prytkov, V. Yu.; Rukoyatkin, P. A.; Schedrov, V. A.; Schevelev, O. N.; Shilov, S. N.; Shindin, R. A.; Slunecka, M.; Slunečková, V.; Starikov, A. Yu.; Stoletov, G. D.; Strunov, L. N.; Svetov, A. L.; Usov, Yu. A.; Vasiliev, T.; Volkov, V. I.; Vorobiev, E. I.; Yudin, I. P.; Zaitsev, I. V.; Zhdanov, A. A.; Zhmyrov, V. N.

2005-01-01

New accurate data on the neutron-proton spin-dependent total cross section difference Δ σ L( np) at the neutron beam kinetic energies 1.4, 1.7, 1.9 and 2.0 GeV are presented. A number of physical and methodical results on investigation of an elastic np→pn charge exchange process over a few GeV region are also presented. Measurements were carried out at the Synchrophasotron and Nuclotron of the Veksler and Baldin Laboratory of High Energies of the Joint Institute for Nuclear Research.

Spin Orbit Torque in Ferromagnetic Semiconductors

KAUST Repository

Li, Hang

2016-01-01

Electrons not only have charges but also have spin. By utilizing the electron spin, the energy consumption of electronic devices can be reduced, their size can be scaled down and the efficiency of `read' and `write' in memory devices can

Exploring molecular and spin interactions of Tellurium adatom in reduced graphene oxide

Energy Technology Data Exchange (ETDEWEB)

Alegaonkar, Ashwini [Department of Chemistry, Savitribai Phule Pune University (Formerly University of Pune), Ganeshkhind, Pune, 411 007, MS (India); Alegaonkar, Prashant [Department of Applied Physics, Defence Institute of Advance Technology, Girinagar, Pune, 411 025, MS (India); Pardeshi, Satish, E-mail: skpar@chem.unipune.ac.in [Department of Chemistry, Savitribai Phule Pune University (Formerly University of Pune), Ganeshkhind, Pune, 411 007, MS (India)

2017-07-01

The transport of spin information fundamentally requires favourable molecular architecture and tunable spin moments to make the medium pertinent for spintronic. We report on achieving coherent molecular-spin parameters for rGO due to Tellurium (Te) adatom. Initially, GO prepared using graphite, was modified into rGO by in situ incorporation of 1 (w/w)% of Te. Both the systems were subjected to ESCA, FTIR, Raman dispersion, ESR spectroscopy, and electron microscopy. Analysis revealed that, Te substantially reacted with epoxides, carbonyl, and carboxylate groups that improved C-to-O ratio by twice. However, the spin splitting character, between Te and C, seems to be quenched. Moreover, Te altered the dynamical force constant between C-C and C=C that generated the mechanical stress within rGO network. The layer conjugation, nature of folding, symmetry, and electronic states of the edges were also affected by precipitation and entrapment of Te. The calculated dynamic molecular Raman and ESR spin parameters indicated that, Te acted as a bridging element for long range spin transport. This is particularly due to, the p-orbital moments of Te contributing, vectorially, to spin relaxation process operative at broken inversion symmetry sites. Our study suggests that, facile addition of Te in rGO is useful to achieve favourable spintronic properties. - Highlights: • Spin interactions and molecular dynamics modification due to Tellurium adatom in rGO. • Molecular level manipulation of Tellurium adatom for favourable spintronic properties. • Bychocov-Rashaba coupling are the operative channels in rGO. • Extrinsic coupling component get added vectorially by Tellurium. • Te-rGO is a viable medium for molecular spintronics.

Probing quantum coherence in single-atom electron spin resonance

Science.gov (United States)

Willke, Philip; Paul, William; Natterer, Fabian D.; Yang, Kai; Bae, Yujeong; Choi, Taeyoung; Fernández-Rossier, Joaquin; Heinrich, Andreas J.; Lutz, Christoper P.

2018-01-01

Spin resonance of individual spin centers allows applications ranging from quantum information technology to atomic-scale magnetometry. To protect the quantum properties of a spin, control over its local environment, including energy relaxation and decoherence processes, is crucial. However, in most existing architectures, the environment remains fixed by the crystal structure and electrical contacts. Recently, spin-polarized scanning tunneling microscopy (STM), in combination with electron spin resonance (ESR), allowed the study of single adatoms and inter-atomic coupling with an unprecedented combination of spatial and energy resolution. We elucidate and control the interplay of an Fe single spin with its atomic-scale environment by precisely tuning the phase coherence time T2 using the STM tip as a variable electrode. We find that the decoherence rate is the sum of two main contributions. The first scales linearly with tunnel current and shows that, on average, every tunneling electron causes one dephasing event. The second, effective even without current, arises from thermally activated spin-flip processes of tip spins. Understanding these interactions allows us to maximize T2 and improve the energy resolution. It also allows us to maximize the amplitude of the ESR signal, which supports measurements even at elevated temperatures as high as 4 K. Thus, ESR-STM allows control of quantum coherence in individual, electrically accessible spins. PMID:29464211

Ballistic spin filtering across the ferromagnetic-semiconductor interface

Directory of Open Access Journals (Sweden)

Y.H. Li

2012-03-01

Full Text Available The ballistic spin-filter effect from a ferromagnetic metal into a semiconductor has theoretically been studied with an intention of detecting the spin polarizability of density of states in FM layer at a higher energy level. The physical model for the ballistic spin filtering across the interface between ferromagnetic metals and semiconductor superlattice is developed by exciting the spin polarized electrons into n-type AlAs/GaAs superlattice layer at a much higher energy level and then ballistically tunneling through the barrier into the ferromagnetic film. Since both the helicity-modulated and static photocurrent responses are experimentally measurable quantities, the physical quantity of interest, the relative asymmetry of spin-polarized tunneling conductance, could be extracted experimentally in a more straightforward way, as compared with previous models. The present physical model serves guidance for studying spin detection with advanced performance in the future.

Experimental parameters for quantitative surface analysis by medium energy ion scattering, ch. 1

International Nuclear Information System (INIS)

Turkenburg, W.C.; Kersten, H.H.; Colenbrander, B.G.; Jongh, A.P. de; Saris, F.W.

1976-01-01

A new UHV chamber for surface and surface layer analysis by collision spectroscopy of backscattered ions at medium energies is described. Experimental parameters like energy, angular and depth resolution, crystal alignment and background pressure are discussed. Formulae based on the use of an electrostatic energy analyser show that the analysis can be quantitative. Effects of beam induced build-up of a hydro-carbon layer, sputter cleaning and creation of radiation damage have been investigated for Cu (110) and Ni (110). Detection sensitivity for Carbon, Oxygen and Sulfur on Cu and Ni has been found to be 0.2, 0.1 and 0.03 of a monolayer respectively

The spin structure of the nucleon

International Nuclear Information System (INIS)

Deur, A.

2008-02-01

This document describes the recent experimental results on the spin structure of the nucleon obtained with the electron accelerator Thomas Jefferson National Facility (Jefferson Lab), Virginia. We first discuss the goal of studying the nucleon spin structure and give the basis and phenomenology of high energy lepton scattering. Then, we discuss with some details a few sum rules concerning the spin structure of the nucleon. Those are important tools for studying the nucleon spin structure at Jefferson Lab. We then describe the present experimental situation and analyze the results. We have been able to determine an effective coupling constant for the strong interaction for any regime of quantum chromodynamics which proves that QCD is an approximately conformal theory. We conclude on the perspectives for this field of research, in particular with the 12 GeV energy upgrade of Jefferson Lab. The top priority will be the measurement of generalised parton distributions. The only issue that will stay misunderstood is the role of the very low x domain on the spin structure of the nucleon

A New Spin on Photoemission Spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Jozwiak, Chris [Univ. of California, Berkeley, CA (United States)

2008-12-01

The electronic spin degree of freedom is of general fundamental importance to all matter. Understanding its complex roles and behavior in the solid state, particularly in highly correlated and magnetic materials, has grown increasingly desirable as technology demands advanced devices and materials based on ever stricter comprehension and control of the electron spin. However, direct and efficient spin dependent probes of electronic structure are currently lacking. Angle Resolved Photoemission Spectroscopy (ARPES) has become one of the most successful experimental tools for elucidating solid state electronic structures, bolstered by-continual breakthroughs in efficient instrumentation. In contrast, spin-resolved photoemission spectroscopy has lagged behind due to a lack of similar instrumental advances. The power of photoemission spectroscopy and the pertinence of electronic spin in the current research climate combine to make breakthroughs in Spin and Angle Resolved Photoemission Spectroscopy (SARPES) a high priority . This thesis details the development of a unique instrument for efficient SARPES and represents a radical departure from conventional methods. A custom designed spin polarimeter based on low energy exchange scattering is developed, with projected efficiency gains of two orders of magnitude over current state-of-the-art polarimeters. For energy analysis, the popular hemispherical analyzer is eschewed for a custom Time-of-Flight (TOF) analyzer offering an additional order of magnitude gain in efficiency. The combined instrument signifies the breakthrough needed to perform the high resolution SARPES experiments necessary for untangling the complex spin-dependent electronic structures central to today's condensed matter physics.

Spin-density functional for exchange anisotropic Heisenberg model

International Nuclear Information System (INIS)

Prata, G.N.; Penteado, P.H.; Souza, F.C.; Libero, Valter L.

2009-01-01

Ground-state energies for antiferromagnetic Heisenberg models with exchange anisotropy are estimated by means of a local-spin approximation made in the context of the density functional theory. Correlation energy is obtained using the non-linear spin-wave theory for homogeneous systems from which the spin functional is built. Although applicable to chains of any size, the results are shown for small number of sites, to exhibit finite-size effects and allow comparison with exact-numerical data from direct diagonalization of small chains.

The study of quasi-projectiles produced in Ni+Ni and Ni+Au collisions: excitation energy and spin; Etude des quasi-projectiles produits dans les collisions Ni+Ni et Ni+Au: energie d'excitation et spin

Energy Technology Data Exchange (ETDEWEB)

Buta, A

2003-02-01

During the collision between the projectile and the target nuclei in the intermediate energy regime (E < 100 MeV/nucleon) two excited nuclei are mainly observed in the exit channel, the quasi projectile (QP) and the quasi target. They disintegrate by particle emission. However, this binary picture is perturbed by the emission of particles and light fragments with velocities intermediate between the projectile velocity and the target one, all along the interaction (midrapidity component). This work aim to determine the excitation energy and the intrinsic angular momentum (or spin) of quasi-projectiles produced in the Ni+Ni and Ni+Au collisions at 52 and 90 MeV/nucleon. The excitation energy is deduced from the kinematical characteristics of particles emitted by the quasi-projectile. They have to be separated from midrapidity particles. Three different scenarios have been used for this purpose. The spin of the quasi-projectile has been extracted from the experimental data by mean of proton and alpha particles multiplicities emitted by the QP in the Ni+Au at 52 MeV/nucleon reaction. The results have been compared to the predictions of a theoretical model based on nucleon transfers. Their evolution is qualitatively reproduced as a function of the violence of the collision. (author)

MRI of the liver with the new contrast medium Gd-BOPTA

International Nuclear Information System (INIS)

Vogl, T.J.; Pegios, W.; Balzer, J.; Lissner, J.; Pirovano, G.

1992-01-01

A phase 1 study on 8 normals has been carried out to determine the effectiveness and safety during MRI of a new hepatobiliary contrast medium Gd-BOPTA for causing enhancement of the upper abdominal organs. Gradient echo sequences (flash), T 1 and T 2 -weighted spin echo sequences and turbo-flash sequences were used. The contrast medium was given as a single infusion in various concentrations (0.005, 0.05, 0.1 and 0.2 mmol/kg body weight). Optimal contrast of liver parenchyma was obtained with a dose of 0.05-0.1 mmol/kg body weight, resulting in contrast increase of 149.1% during gradient echo sequences and 107.8% during T 1 spin echo sequences. In general, the increased contrast lasted for about two hours. Because of the biliary and renal excretion there was an enormous increase in signal intensity of the bile ducts and a significant increase in the kidneys and ureters. The results of the first in-vivo-trial of Gd-BOPTA encourages the performance of further clinical studies of this new hepatobiliary contrast medium. (orig.) [de

Examples from P2 and energy assessments at small to medium size manufacturers

International Nuclear Information System (INIS)

Fleischman, M.; Watters, J.C.; Cobourn, W.G.; Collins, D.J.

1996-01-01

Using engineering student-faculty teams, the U.S. Department of energy sponsored industrial assessment center (IAC) at the university of louisville does free pollution prevention and energy assessments at small to medium size manufacturers (SIC 20-39) in kentucky and indiana. Each client plant must meet three of the following four criteria: Annual energy bills less than $1, 750, 000 and more than $50, 00. Gross annual sales of less than $75 million. Less than 500 employees. Lack a dedicated energy/waste engineer. Lack of in-house staff to perform these analyses. The program criteria and assessment procedures are briefly described and summaries of assessment at a sheet fed offset (lithographic) printing plant and 2 denim jeans pre washing plants are presented. 4 figs., 8 tabs

High spin structure of nuclei near N = 50 shell gap and search for high-spin isomers using time stamped data

International Nuclear Information System (INIS)

Saha, S.; Palit, R.; Trivedi, T.; Sethi, J.; Joshi, P.K.; Naidu, B.S.; Donthi, R.; Jadhav, S.; Nanal, V.; Pillay, R.G.; Jain, H.C.; Kumar, S.; Biswas, D.C.; Mukherjee, G.; Saha, S.

2011-01-01

Information on the high-spin states of nuclei promises to provide stringent test of the interaction of the Hamiltonian used in the calculation due to smaller basis space for high J-values. It is reported in a recent shell model review that no interaction is optimized for the region of interest around N = 50 and Z = 40 shell closure. The detailed spectroscopic information of the medium and high spin states in these nuclei is required to understand the shape transition between spherical and deformed shapes at N =60 as the higher orbitals are filled. Structure of isomers near shell closure carries important information of, for example, the extent of core excitation. In the present work, the spectroscopic study of the high spin states of 89 Zr isotope have been discussed

A method for the accurate determination of the polarization of a neutron beam using a polarized 3He spin filter

International Nuclear Information System (INIS)

Greene, G.L.; Thompson, A.K.; Dewey, M.S.

1995-01-01

A new method for the accurate determination of the degree of polarization of a neutron beam which has been polarized by transmission through a spin polarized 3 He cell is given. The method does not require the use of an analyzer or spin flipper nor does it require an accurate independent determination of the 3 He polarization. The method provides a continuous on-line determination of the neutron polarization. The method may be of use in the accurate determination of correlation coefficients in neutron beta decay which provide a test of the standard model for the electroweak interaction. The method may also provide an accurate procedure for the calibration of polarized 3 He targets used in medium and high energy scattering experiments. ((orig.))

Duplex quantum communication through a spin chain

Science.gov (United States)

Wang, Zhao-Ming; Bishop, C. Allen; Gu, Yong-Jian; Shao, Bin

2011-08-01

Data multiplexing within a quantum computer can allow for the simultaneous transfer of multiple streams of information over a shared medium thereby minimizing the number of channels needed for requisite data transmission. Here, we investigate a two-way quantum communication protocol using a spin chain placed in an external magnetic field. In our scheme, Alice and Bob each play the role of a sender and a receiver as two states, cos((θ1)/(2))0+sin((θ1)/(2))eiφ11 and cos((θ2)/(2))0+sin((θ2)/(2))eiφ21, are transferred through one channel simultaneously. We find that the transmission fidelity at each end of a spin chain can usually be enhanced by the presence of a second party. This is an important result for establishing the viability of duplex quantum communication through spin chain networks.

Spin dynamics in the single molecule magnet Ni4 under microwave irradiation

Science.gov (United States)

de Loubens, Gregoire

2009-03-01

Quantum mechanical effects such as quantum tunneling of magnetization (QTM) and quantum phase interference have been intensively studied in single molecule magnets (SMMs). These materials have also been suggested as candidates for qubits and are promising for molecular spintronics. Understanding decoherence and energy relaxation mechanisms in SMMs is then both of fundamental interest and important for the use of SMMs in applications. Interestingly, the single-spin relaxation rate due to direct process of a SMM embedded in an elastic medium can be derived without any unknown coupling constant [1]. Moreover, nontrivial relaxation mechanisms are expected from collective effects in SMM single crystals, such as phonon superradiance or phonon bottleneck. In order to investigate the spin relaxation between the two lowest lying spin-states of the S=4 single molecule magnet Ni4, we have developed an integrated sensor that combines a microstrip resonator and micro-Hall effect magnetometer on a chip [2]. This sensor enables both real time studies of magnetization dynamics under pulse irradiation as well as simultaneous measurements of the absorbed power and magnetization changes under continuous microwave irradiation. The latter technique permits the study of small deviations from equilibrium under steady state conditions, i.e. small amplitude cw microwave irradiation. This has been used to determine the energy relaxation rate of a Ni4 single crystal as a function of temperature at two frequencies, 10 and 27.8 GHz. A strong temperature dependence is observed below 1.5 K, which is not consistent with a direct spin-phonon relaxation process. The data instead suggest that the spin relaxation is dominated by a phonon bottleneck at low temperatures and occurs by an Orbach process involving excited spin-levels at higher temperatures [3]. Experimental results will be compared with detailed calculations of the relaxation rate using the density matrix equation with the relaxation

Unique electron polarimeter analyzing power comparison and precision spin-based energy measurement

International Nuclear Information System (INIS)

Joseph Grames; Charles Sinclair; Joseph Mitchell; Eugene Chudakov; Howard Fenker; Arne Freyberger; Douglas Higinbotham; Poelker, B.; Michael Steigerwald; Michael Tiefenback; Christian Cavata; Stephanie Escoffier; Frederic Marie; Thierry Pussieux; Pascal Vernin; Samuel Danagoulian; Kahanawita Dharmawardane; Renee Fatemi; Kyungseon Joo; Markus Zeier; Viktor Gorbenko; Rakhsha Nasseripour; Brian Raue; Riad Suleiman; Benedikt Zihlmann

2004-01-01

Precision measurements of the relative analyzing powers of five electron beam polarimeters, based on Compton, Moller, and Mott scattering, have been performed using the CEBAF accelerator at the Thomas Jefferson National Accelerator Facility (Jefferson Laboratory). A Wien filter in the 100 keV beamline of the injector was used to vary the electron spin orientation exiting the injector. High statistical precision measurements of the scattering asymmetry as a function of the spin orientation were made with each polarimeter. Since each polarimeter receives beam with the same magnitude of polarization, these asymmetry measurements permit a high statistical precision comparison of the relative analyzing powers of the five polarimeters. This is the first time a precise comparison of the analyzing powers of Compton, Moller, and Mott scattering polarimeters has been made. Statistically significant disagreements among the values of the beam polarization calculated from the asymmetry measurements made with each polarimeter reveal either errors in the values of the analyzing power, or failure to correctly include all systematic effects. The measurements reported here represent a first step toward understanding the systematic effects of these electron polarimeters. Such studies are necessary to realize high absolute accuracy (ca. 1%) electron polarization measurements, as required for some parity violation measurements planned at Jefferson Laboratory. Finally, a comparison of the value of the spin orientation exiting the injector that provides maximum longitudinal polarization in each experimental hall leads to an independent and very precise (better than 10-4) absolute measurement of the final electron beam energy

Neutron Spin Resonance in the 112-Type Iron-Based Superconductor

Science.gov (United States)

Xie, Tao; Gong, Dongliang; Ghosh, Haranath; Ghosh, Abyay; Soda, Minoru; Masuda, Takatsugu; Itoh, Shinichi; Bourdarot, Frédéric; Regnault, Louis-Pierre; Danilkin, Sergey; Li, Shiliang; Luo, Huiqian

2018-03-01

We use inelastic neutron scattering to study the low-energy spin excitations of the 112-type iron pnictide Ca0.82La0.18Fe0.96Ni0.04As2 with bulk superconductivity below Tc=22 K . A two-dimensional spin resonance mode is found around E =11 meV , where the resonance energy is almost temperature independent and linearly scales with Tc along with other iron-based superconductors. Polarized neutron analysis reveals the resonance is nearly isotropic in spin space without any L modulations. Because of the unique monoclinic structure with additional zigzag arsenic chains, the As 4 p orbitals contribute to a three-dimensional hole pocket around the Γ point and an extra electron pocket at the X point. Our results suggest that the energy and momentum distribution of the spin resonance does not directly respond to the kz dependence of the fermiology, and the spin resonance intrinsically is a spin-1 mode from singlet-triplet excitations of the Cooper pairs in the case of weak spin-orbital coupling.

Measurement of the depolarization of the reaction 27Al (p vector, p vector.) 27Al for the study of the spin-spin potential

International Nuclear Information System (INIS)

Loeh, H.

1981-01-01

For the study of the spin-spin interactions in the optical potential the depolarization in the elastic scattering of polarized protons was measured. The double-scattering experiments were performed in the angular range 40 0 -110 0 at an incident energy of 10.35 MeV at the Erlangen QD magnetic spectrometer. The determination of the optical model parameters independent from the spin-spin potentials resulted by the fit of those to the observables and sigmasup(di). These were obtained from a measurement of the angular distribution of the analyzing power and the differential cross section in the 4π-scattering chamber for the reaction 27 Al (p vector,psub(o)) at the same energy. The compound contributions present at this energy, which can also influence the depolarization, were regarded by the calculation of the compound-elastic non-spin-flip respectively spin-flip subcross sections by means of the formalism of Hofmann, Richard, Tepel, and Weidenmueller. Because of the target nucleus 27 Al posesses in the ground state a spin I=5/2 also the possible quadrupole spin flip had to be included in the analysis. This was performed by coupled channel calculations. The depolarization data corrected according to compound contributions and quadrupole effects could now be applied to the study of the spin-spin potentials by means of DWBA calculations. As result it turned out that for the description of the experimental data a spherical spin-spin potential of the strength Vsub(SS)=1.5+-0.3 MeV had to be assumed. For the addition of a tensor term however no necessity resulted. (orig.) [de

Dual Energy CT Angiography of Peripheral Arterial Disease: Feasibility of Using Lower Contrast Medium Volume.

Directory of Open Access Journals (Sweden)

Abdulrahman Almutairi

Full Text Available One of the main drawbacks associated with Dual Energy Computed Tomography Angiography (DECTA is the risk of developing contrast medium-induced nephropathy (CIN. The aim of the present study was firstly, to design an optimal CT imaging protocol by determining the feasibility of using a reduced contrast medium volume in peripheral arterial DECTA, and secondly, to compare the results with those obtained from using routine contrast medium volume.Thirty four patients underwent DECTA for the diagnosis of peripheral arterial disease. They were randomly divided into two groups: Group 1 (routine contrast volume group with n = 17, injection rate 4-5 ml/s, and 1.5 ml/kg of contrast medium, and Group 2 ((low contrast volume group, with n = 17, injection rate 4-5ml/s, and contrast medium volume 0.75 ml/kg. A fast kilovoltage-switching 64-slice CT scanner in the dual-energy mode was employed for the study. A total of 6 datasets of monochromatic images at 50, 55, 60, 65, 70 and 75 keV levels were reconstructed with adaptive statistical iterative reconstruction (ASIR at 50%. A 4-point scale was the tool for qualitative analysis of results. The two groups were compared and assessed quantitatively for image quality on the basis of signal-to-noise ratio (SNR and contrast-to-noise-ratio (CNR. Radiation and contrast medium doses were also compared.The overall mean CT attenuation and mean noise for all lower extremity body parts was significantly lower for the low volume contrast group (p<0.001, and varied significantly between groups (p = 0.001, body parts (p<0.001 and keVs (p<0.001. The interaction between group body parts was significant with CT attenuation and CNR (p = 0.002 and 0.003 respectively, and marginally significant with SNR (p = 0.047, with minimal changes noticed between the two groups. Group 2 (low contrast volume group displayed the lowest image noise between 65 and 70 keV, recorded the highest SNR and CNR at 65 keV, and produced significantly lower

Effects of the electron-electron interaction in the spin resonance in 2D systems with Dresselhaus spin-orbit coupling

International Nuclear Information System (INIS)

Krishtopenko, S. S.

2015-01-01

The effect of the electron-electron interaction on the spin-resonance frequency in two-dimensional electron systems with Dresselhaus spin-orbit coupling is investigated. The oscillatory dependence of many-body corrections on the magnetic field is demonstrated. It is shown that the consideration of many-body interaction leads to a decrease or an increase in the spin-resonance frequency, depending on the sign of the g factor. It is found that the term cubic in quasimomentum in Dresselhaus spin-orbit coupling partially decreases exchange corrections to the spin resonance energy in a two-dimensional system

Effects of the electron-electron interaction in the spin resonance in 2D systems with Dresselhaus spin-orbit coupling

Energy Technology Data Exchange (ETDEWEB)

Krishtopenko, S. S., E-mail: sergey.krishtopenko@mail.ru [Russian Academy of Sciences, Institute for Physics of Microstructures (Russian Federation)

2015-02-15

The effect of the electron-electron interaction on the spin-resonance frequency in two-dimensional electron systems with Dresselhaus spin-orbit coupling is investigated. The oscillatory dependence of many-body corrections on the magnetic field is demonstrated. It is shown that the consideration of many-body interaction leads to a decrease or an increase in the spin-resonance frequency, depending on the sign of the g factor. It is found that the term cubic in quasimomentum in Dresselhaus spin-orbit coupling partially decreases exchange corrections to the spin resonance energy in a two-dimensional system.

Energy dispersion of the electrosubbands in parabolic confining quantum wires: interplay of Rashba, Dresselhaus, lateral spin-orbit interaction and the Zeeman effect

International Nuclear Information System (INIS)

Zhang Tongyi; Zhao Wei; Liu Xueming

2009-01-01

We have made a thorough theoretical investigation of the interplay of spin-orbit interactions (SOIs) resulting from Rashba, Dresselhaus and the lateral parabolic confining potential on the energy dispersion relation of the spin subbands in a parabolic quantum wire. The influence of an applied external magnetic field is also discussed. We show the interplay of different types of SOI, as well as the Zeeman effect, leads to rather complex and intriguing electrosubbands for different spin branches. The effect of different coupling strengths and different magnetic field strengths is also investigated.

Medium Energy measurements on N-N parameters

International Nuclear Information System (INIS)

Ambrose, D.; Bachman, M.; Coffey, P.; Glass, G.; Jobst, B.; McNaughton, K.H.; Nguyen, C.; Riley, P.J.

1992-12-01

Research is reported on the following topics: Spin transfer measurements in np elastic scattering; pp elastic differential cross section measurements; single pion production in np scattering; and a new search for rare kaon decays (K L →μμ and K L →ee). 68 refs., 33 figs, 3 tabs

Stable, metastable and unstable solutions of a spin-1 Ising system based on the free energy surfaces

Science.gov (United States)

Keskİin, Mustafa; Özgan, Şükrü

1990-04-01

Stable, metastable and unstable solutions of a spin-1 Ising model with bilinear and biquadratic interactions are found by using the free energy surfaces. The free energy expression is obtained in the lowest approximation of the cluster variation method. All these solutions are shown in the two-dimensional phase space, especially the unstable solutions which in some cases are difficult to illustrate in the two-dimensional phase space, found by Keskin et al. recently.

SPIN SUSCEPTIBILITY IN HIGH - TC SUPERCONDUCTIVITY

African Journals Online (AJOL)

USER

2012-07-05

Jul 5, 2012 ... remains unchanged as a result of which the oxygen site will remain deficient ... kinetic energy, a hole's spin hooks up with the random Cu moment to form a ... reach out to each other magnetically to form spin singlet pairs with ...

Nuclear Spin Nanomagnet in an Optically Excited Quantum Dot

Science.gov (United States)

Korenev, V. L.

2007-12-01

Linearly polarized light tuned slightly below the optical transition of the negatively charged exciton (trion) in a single quantum dot causes the spontaneous nuclear spin polarization (self-polarization) at a level close to 100%. The effective magnetic field of spin-polarized nuclei shifts the optical transition energy close to resonance with photon energy. The resonantly enhanced Overhauser effect sustains the stability of the nuclear self-polarization even in the absence of spin polarization of the quantum dot electron. As a result the optically selected single quantum dot represents a tiny magnet with the ferromagnetic ordering of nuclear spins—the nuclear spin nanomagnet.

Electron spin-lattice relaxation in fractals

International Nuclear Information System (INIS)

Shrivastava, K.N.

1986-08-01

We have developed the theory of the spin-fracton interaction for paramagnetic ions in fractal structures. The interaction is exponentially damped by the self-similarity length of the fractal and by the range dimensionality d Φ . The relaxation time of the spin due to the absorption and emission of the fracton has been calculated for a general dimensionality called the Raman dimensionality d R , which for the fractons differs from the Hausdorff (fractal) dimensionality, D, as well as from the Euclidean dimensionality, d. The exponent of the energy level separation in the relaxation rate varies with d R d Φ /D. We have calculated the spin relaxation rate due to a new type of Raman process in which one fracton is absorbed to affect a spin transition from one electronic level to another and later another fracton is emitted along with a spin transition such that the difference in the energies of the two fractons is equal to the electronic energy level separation. The temperature and the dimensionality dependence of such a process has been found in several approximations. In one of the approximations where the van Vleck relaxation rate for a spin in a crystal is known to vary with temperature as T 9 , our calculated variation for fractals turns out to be T 6.6 , whereas the experimental value for Fe 3+ in frozen solutions of myoglobin azide is T 6.3 . Since we used d R =4/3 and the fracton range dimensionality d Φ =D/1.8, we expect to measure the dimensionalities of the problem by measuring the temperature dependence of the relaxation times. We have also calculated the shift of the paramagnetic resonance transition for a spin in a fractal for general dimensionalities. (author)

IMPROVING THE MODEL OF EMISSION FROM SPINNING DUST: EFFECTS OF GRAIN WOBBLING AND TRANSIENT SPIN-UP

International Nuclear Information System (INIS)

Hoang, Thiem; Lazarian, A.; Draine, B. T.

2010-01-01

Observations continue to support the interpretation of the anomalous microwave foreground as electric dipole radiation from spinning dust grains as proposed by Draine and Lazarian. In this paper, we present a refinement of the original model by improving the treatment of a number of physical effects. First, we consider a disk-like grain rotating with angular velocity at an arbitrary angle with respect to the grain symmetry axis (i.e., grain wobbling) and derive the rotational damping and excitation coefficients arising from infrared emission, plasma-grain interactions, and electric dipole emission. The angular velocity distribution and the electric dipole emission spectrum for disk-like grains is calculated using the Langevin equation, for cases both with and without fast internal relaxation. Our results show that for fast internal relaxation, the peak emissivity of spinning dust, compared to earlier studies, increases by a factor of ∼2 for the warm neutral medium (WNM), the warm ionized medium (WIM), the cold neutral medium (CNM), and the photodissociation region, and by a factor ∼4 for reflection nebulae. The frequency at the emission peak also increases by factors ∼1.4 to ∼2 for these media. Without internal relaxation, the increase of emissivity is comparable, but the emission spectrum is more extended to higher frequency. The increased emission results from the non-sphericity of grain shape and from the anisotropy in damping and excitation along directions parallel and perpendicular to the grain symmetry axis. Second, we provide a detailed numerical study including transient spin-up of grains by single-ion collisions. The range of grain size in which single-ion collisions are important is identified. The impulses broaden the emission spectrum and increase the peak emissivity for the CNM, WNM, and WIM, although the increases are not as large as those due to the grain wobbling. In addition, we present an improved treatment of rotational excitation and

Prospects for a deuterium internal target, tensor polarized by optical pumping: spin exchange

International Nuclear Information System (INIS)

Green, M.C.

1984-01-01

The prospects for a tensor polarized deuterium target (approx. 10 15 atoms/cm 2 ) appropriate for nuclear physics studies in medium and high energy particle storage rings are discussed. Using the technique of electron spin exchange with an optically pumped sodium (or potassium) vapor, we hope to polarize deuterium at a rate approx. 10 17 atoms/sec. Predictions for the deuterium polarization for a particular target cell design will be presented leading to the identification of the required optical pumping power and cell wall depolarization probability to attain optimum performance. The technical obstacles to be surmounted in such a target design will also be discussed

Spin formalism and applications to new physics searches

Energy Technology Data Exchange (ETDEWEB)

Haber, H.E. [Univ. of California, Santa Cruz, CA (United States)

1994-12-01

An introduction to spin techniques in particle physics is given. Among the topics covered are: helicity formalism and its applications to the decay and scattering of spin-1/2 and spin-1 particles, techniques for evaluating helicity amplitudes (including projection operator methods and the spinor helicity method), and density matrix techniques. The utility of polarization and spin correlations for untangling new physics beyond the Standard Model at future colliders such as the LHC and a high energy e{sup +}e{sup {minus}} linear collider is then considered. A number of detailed examples are explored including the search for low-energy supersymmetry, a non-minimal Higgs boson sector, and new gauge bosons beyond the W{sup {+-}} and Z.

Study of nuclear isovector spin responses from polarization transfer in (p,n) reactions at intermediate energies

International Nuclear Information System (INIS)

Wakasa, Tomotsugu

1997-01-01

We have measured a complete set of polarization transfer observables has been measured for quasi-free (p vector, n vector) reactions on 2 H, 6 Li, 12 C, 40 Ca, and 208 Pb at a bombarding energy of 346MeV and a laboratory scattering angle of 22deg (q=1.7 fm -1 ). The polarization transfer observables for all five targets are remarkably similar. These polarization observables yield separated spin-longitudinal (σ·q) and spin-transverse (σxq) nuclear responses. These results are compared to the spin-transverse responses measured in deep-inelastic electron scattering as well as to nuclear responses based on the random phase approximation. Such a comparison reveals an enhancement in the (p vector, n vector) spin-transverse channel, which masks the effect of pionic correlations in the response ratio. Second, the double differential cross sections at θ lab between 0deg and 12.3deg and the polarization transfer D NN at 0deg for the 90 Zr(p,n) reaction are measured at a bombarding energy of 295MeV. The Gamow-Teller(GT) strength B(GT) in the continuum deduced from the L=0 cross section is compared both with the perturbative calculation by Bertsch and Hamamoto and with the second-order random phase approximation calculation by Drozdz et al. The sum of B(GT) values up to 50MeV excitation becomes S β- =28.0±1.6 after subtracting the contribution of the isovector spin-monopole strength. This S β- value of 28.0±1.6 corresponds to about (93±5)% of the minimum value of the sum-rule 3(N-Z)=30. Last, first measurements of D NN (0deg) for (p vector, n vector) reactions at 295MeV yield large negative values up to 50MeV excitation for the 6 Li, 11 B, 12 C, 13 C(p vector, n vector) reactions. DWIA calculations using the Franey and Love (FL) 270MeV interaction reproduce differential cross sections and D NN (0deg) values, while the FL 325MeV interaction yield D NN (0deg) values less negative than the experimental values. (J.P.N.)

Correlation between the rate of bioreduction of nitroxide spin label by human tumor cells and their low-dose radiation response

International Nuclear Information System (INIS)

Halpern, H.J.; Peric, M.; Nguyen, T.D.; Spencer, D.P.; Bowman, M.K.; Beckett, M.; Weichselbaum, R.R.

1988-01-01

The authors discuss a correlation observed between the bioreduction of nitroxide spin label by four human tumor cell lines and a normal tissue fibroblast clone and their low-dose radiation response, specifically their D Q . In measurements of the bioreduction rate of several other cell lines, this correlation appears to persist. In order to define the mechanism of this correlation, they have begun by subtly altering the measurement conditions. The original conditions for measurement involved adding the spin label to cells whose culture medium had been changed (the label was added to the new medium). By delaying the addition of the label to the culture medium, they substantially reduced the variation of the bioreduction rate between the cell lines. This implies that the fresh medium provides a nonspecific irritant or disequilibrium to the cultured cell system to which they response variably by accelerating, among other things, the metabolic process responsible for spin label bioreduction

Tunneling conductance of a two-dimensional electron gas with Dresselhaus spin-orbit coupling

International Nuclear Information System (INIS)

Srisongmuang, B.; Ka-oey, A.

2012-01-01

We theoretically studied the spin-dependent charge transport in a two-dimensional electron gas with Dresselhaus spin-orbit coupling (DSOC) and metal junctions. It is shown that the DSOC energy can be directly measured from the tunneling conductance spectrum. We found that spin polarization of the conductance in the propagation direction can be obtained by injecting from the DSOC system. We also considered the effect of the interfacial scattering barrier (both spin-flip and non-spin-flip scattering) on the overall conductance and the spin polarization of the conductance. It is found that the increase of spin-flip scattering can enhance the conductance under certain conditions. Moreover, both types of scattering can increase the spin polarization below the branches crossing of the energy band. - Highlights: → DSOC energy can be directly measured from tunneling conductance spectrum. → Spin polarization of conductance in the propagation direction can be obtained by injecting from DSOC system. → Both types of scattering can increase spin polarization.

The effect of output-input isolation on the scaling and energy consumption of all-spin logic devices

International Nuclear Information System (INIS)

Hu, Jiaxi; Haratipour, Nazila; Koester, Steven J.

2015-01-01

All-spin logic (ASL) is a novel approach for digital logic applications wherein spin is used as the state variable instead of charge. One of the challenges in realizing a practical ASL system is the need to ensure non-reciprocity, meaning the information flows from input to output, not vice versa. One approach described previously, is to introduce an asymmetric ground contact, and while this approach was shown to be effective, it remains unclear as to the optimal approach for achieving non-reciprocity in ASL. In this study, we quantitatively analyze techniques to achieve non-reciprocity in ASL devices, and we specifically compare the effect of using asymmetric ground position and dipole-coupled output/input isolation. For this analysis, we simulate the switching dynamics of multiple-stage logic devices with FePt and FePd perpendicular magnetic anisotropy materials using a combination of a matrix-based spin circuit model coupled to the Landau–Lifshitz–Gilbert equation. The dipole field is included in this model and can act as both a desirable means of coupling magnets and a source of noise. The dynamic energy consumption has been calculated for these schemes, as a function of input/output magnet separation, and the results show that using a scheme that electrically isolates logic stages produces superior non-reciprocity, thus allowing both improved scaling and reduced energy consumption

The effect of output-input isolation on the scaling and energy consumption of all-spin logic devices

Energy Technology Data Exchange (ETDEWEB)

Hu, Jiaxi; Haratipour, Nazila; Koester, Steven J., E-mail: skoester@umn.edu [Department of Electrical and Computer Engineering, University of Minnesota-Twin Cities, 200 Union St. SE, Minneapolis, Minnesota 55455 (United States)

2015-05-07

All-spin logic (ASL) is a novel approach for digital logic applications wherein spin is used as the state variable instead of charge. One of the challenges in realizing a practical ASL system is the need to ensure non-reciprocity, meaning the information flows from input to output, not vice versa. One approach described previously, is to introduce an asymmetric ground contact, and while this approach was shown to be effective, it remains unclear as to the optimal approach for achieving non-reciprocity in ASL. In this study, we quantitatively analyze techniques to achieve non-reciprocity in ASL devices, and we specifically compare the effect of using asymmetric ground position and dipole-coupled output/input isolation. For this analysis, we simulate the switching dynamics of multiple-stage logic devices with FePt and FePd perpendicular magnetic anisotropy materials using a combination of a matrix-based spin circuit model coupled to the Landau–Lifshitz–Gilbert equation. The dipole field is included in this model and can act as both a desirable means of coupling magnets and a source of noise. The dynamic energy consumption has been calculated for these schemes, as a function of input/output magnet separation, and the results show that using a scheme that electrically isolates logic stages produces superior non-reciprocity, thus allowing both improved scaling and reduced energy consumption.

Spin wave spectrum of magnetic nanotubes

International Nuclear Information System (INIS)

Gonzalez, A.L.; Landeros, P.; Nunez, Alvaro S.

2010-01-01

We investigate the spin wave spectra associated to a vortex domain wall confined within a ferromagnetic nanotube. Basing our study upon a simple model for the energy functional we obtain the dispersion relation, the density of states and dissipation induced life-times of the spin wave excitations in presence of a magnetic domain wall. Our aim is to capture the basics spin wave physics behind the geometrical confinement of nobel magnetic textures.

Medium energy measurements of N-N parameters

International Nuclear Information System (INIS)

Riley, P.J.

1990-01-01

This paper discusses the following topics: pp elastic absolute cross section measurement; spin transfer measurements in np elastic scattering; single pion production in np scattering; photoproduction of high P t jets in the wide band beam of the tevatron; and search for K L 0 → μe, K L 0 → ee

Global positioning of spin GPS scheme for half-spin massive spinors

CERN Document Server

Jadach, Stanislaw; Was, Zbigniew

2001-01-01

We present a simple and flexible method of keeping track of the complex phases and spin quantisation axes for half-spin initial- and final-state Weyl spinors in scattering amplitudes of Standard Model high energy physics processes. Both cases of massless and massive spinors are discussed. The method is demonstrated and checked numerically for spin correlations in tau tau production and decay. Its application is in our work of combining effects due to multiple photon emission (exponentiation) and spin, embodied in the Monte Carlo event generators for production and decay of unstable fermions such as the, tau lepton, t-quark and hypothetical new heavy particles. In particular, the recurrent problem of combining, for such unstable fermions, one author's calculation of production and another author's calculation of decay, in the presence or absence of multiple photon effects, is there given a practical solution, both for Weyl spinor methods and for the traditional Jacob-Wick helicity methods. Moreover, for massiv...

Antiresonance induced spin-polarized current generation

Science.gov (United States)

Yin, Sun; Min, Wen-Jing; Gao, Kun; Xie, Shi-Jie; Liu, De-Sheng

2011-12-01

According to the one-dimensional antiresonance effect (Wang X R, Wang Y and Sun Z Z 2003 Phys. Rev. B 65 193402), we propose a possible spin-polarized current generation device. Our proposed model consists of one chain and an impurity coupling to the chain. The energy level of the impurity can be occupied by an electron with a specific spin, and the electron with such a spin is blocked because of the antiresonance effect. Based on this phenomenon our model can generate the spin-polarized current flowing through the chain due to different polarization rates. On the other hand, the device can also be used to measure the generated spin accumulation. Our model is feasible with today's technology.

Environmental Effects on Quantum Reversal of Mesoscopic Spins

Science.gov (United States)

Giraud, R.; Chiorescu, I.; Wernsdorfer, W.; Barbara, B.; Jansen, A. G. M.; Caneschi, A.; Mueller, A.; Tkachuk, A. M.

2002-10-01

We describe what we learnt these last years on quantum reversal of large magnetic moments, using mainly conventional SQUID or micro-SQUID magnetometry. Beside the case of ferromagnetic nanoparticles with 103 - 105 atoms (e.g. Co, Ni, Fe, Ferrites), most fruitful systems appeared to be ensembles of magnetic molecules. These molecules, generally arranged in single crystals, carry relatively small magnetic moments (S = 10 in Mn12-ac and Fe8). They are sufficiently apart from each other not to be coupled by exchange interactions. The ground multiplet is split over an energy barrier of tens of kelvin (≈ 67 K for Mn12) by a strong local crystal field, leading to an Ising-type ground-state. Only weak inter-molecular dipolar interactions are present, as well as intra-molecular interactions, such as hyperfine interactions. Quantum properties of molecule spins are crucially dependent on their magnetic environment of electronic and nuclear spins (the spin bath). Energy fluctuations of the spin bath of about 0.1 K are important, especially at very low temperatures. In particular, they are much larger than the ground-state tunnel splitting of large-spin molecules in low applied fields, of about 10-8 K or even less (such a low value is due to the presence of large energy barriers). Theoretical predictions are experimentally checked for tunneling effects in the presence of non-equilibrated or equilibrated spin-energy distribution. It is also shown that the phonon-bath plays no role in low field, except when the temperature approaches the cross-over temperature to the thermal activation regime. In fact, spin-phonon transitions can play a role only if the tunnel splitting is not too small in comparison with kBT. This is the case both for large-spin molecules in a large magnetic field (e.g. Mn12-ac in a few tesla) and for low-spin molecules, as shown with the study of the molecule V15 (Hilbert space dimension as large as 215 and spin 1/2). We also give our latest results on the

Low-energy spin dynamics of orthoferrites AFeO3 (A  =  Y, La, Bi)

Science.gov (United States)

Park, Kisoo; Sim, Hasung; Leiner, Jonathan C.; Yoshida, Yoshiyuki; Jeong, Jaehong; Yano, Shin-ichiro; Gardner, Jason; Bourges, Philippe; Klicpera, Milan; Sechovský, Vladimír; Boehm, Martin; Park, Je-Geun

2018-06-01

YFeO3 and LaFeO3 are members of the rare-earth orthoferrites family with Pbnm space group. Using inelastic neutron scattering, the low-energy spin excitations have been measured around the magnetic Brillouin zone center. Splitting of magnon branches and finite magnon gaps (∼2 meV) are observed for both compounds, where the Dzyaloshinsky–Moriya interactions account for most of this gap with some additional contribution from single-ion anisotropy. We also make comparisons with multiferroic BiFeO3 (R3c space group), in which similar behavior was observed. By taking into account all relevant local Dzyaloshinsky–Moriya interactions, our analysis allows for the precise determination of all experimentally observed parameters in the spin-Hamiltonian. We find that different properties of the Pbnm and R3c space group lead to the stabilization of a spin cycloid structure in the latter case but not in the former, which explains the difference in the levels of complexity of magnon band structures for the respective compounds.

High spin structure functions

International Nuclear Information System (INIS)

Khan, H.

1990-01-01

This thesis explores deep inelastic scattering of a lepton beam from a polarized nuclear target with spin J=1. After reviewing the formation for spin-1/2, the structure functions for a spin-1 target are defined in terms of the helicity amplitudes for forward compton scattering. A version of the convolution model, which incorporates relativistic and binding energy corrections is used to calculate the structure functions of a neutron target. A simple parameterization of these structure functions is given in terms of a few neutron wave function parameters and the free nucleon structure functions. This allows for an easy comparison of structure functions calculated using different neutron models. (author)

Multiphoton electronic-spin generation and transmission spectroscopy in n-type GaAs

Energy Technology Data Exchange (ETDEWEB)

Idrish Miah, M., E-mail: m.miah@griffith.edu.a [Department of Physics, University of Chittagong, Chittagong 4331 (Bangladesh)

2011-01-17

Multiphoton electronic-spin generation in semiconductors was investigated using differential transmission spectroscopy. The generation of the electronic spins in the semiconductor samples were achieved by multiphoton pumping with circularly polarized light beam and was probed by the spin-resolved transmission of the samples. The electronic spin-polarization of conduction band was estimated and was found to depend on the delay of the probe beam, temperature as well as on the multiphoton pumping energy. The temperature dependence showed a decrease of the spin-polarization with increasing temperature. The electronic spin-polarization was found to depolarize rapidly for multiphoton pumping energy larger than the energy gap of the split-off band to the conduction band. The results were compared with those obtained in one-photon pumping, which shows that an enhancement of the electronic spin-polarization was achieved in multiphoton pumping. The findings resulting from this investigation might have potential applications in opto-spintronics, where the generation of highly polarized electronic spins is required.

Multiphoton electronic-spin generation and transmission spectroscopy in n-type GaAs

International Nuclear Information System (INIS)

Idrish Miah, M.

2011-01-01

Multiphoton electronic-spin generation in semiconductors was investigated using differential transmission spectroscopy. The generation of the electronic spins in the semiconductor samples were achieved by multiphoton pumping with circularly polarized light beam and was probed by the spin-resolved transmission of the samples. The electronic spin-polarization of conduction band was estimated and was found to depend on the delay of the probe beam, temperature as well as on the multiphoton pumping energy. The temperature dependence showed a decrease of the spin-polarization with increasing temperature. The electronic spin-polarization was found to depolarize rapidly for multiphoton pumping energy larger than the energy gap of the split-off band to the conduction band. The results were compared with those obtained in one-photon pumping, which shows that an enhancement of the electronic spin-polarization was achieved in multiphoton pumping. The findings resulting from this investigation might have potential applications in opto-spintronics, where the generation of highly polarized electronic spins is required.

Technical Support Document: Development of the Advanced Energy Design Guide for Medium to Big Box Retail Buildings - 50% Energy Savings

Energy Technology Data Exchange (ETDEWEB)

Bonnema, Eric [National Renewable Energy Lab. (NREL), Golden, CO (United States); Leach, Matt [National Renewable Energy Lab. (NREL), Golden, CO (United States); Pless, Shanti [National Renewable Energy Lab. (NREL), Golden, CO (United States)

2013-06-05

This Technical Support Document describes the process and methodology for the development of the Advanced Energy Design Guide for Medium to Big Box Retail Buildings: Achieving 50% Energy Savings Toward a Net Zero Energy Building (AEDG-MBBR) ASHRAE et al. (2011b). The AEDG-MBBR is intended to provide recommendations for achieving 50% whole-building energy savings in retail stores over levels achieved by following ANSI/ASHRAE/IESNA Standard 90.1-2004, Energy Standard for Buildings Except Low-Rise Residential Buildings (Standard 90.1-2004) (ASHRAE 2004b). The AEDG-MBBR was developed in collaboration with the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE), the American Institute of Architects (AIA), the Illuminating Engineering Society of North America (IES), the U.S. Green Building Council (USGBC), and the U.S. Department of Energy.

Technical Support Document: Development of the Advanced Energy Design Guide for Medium to Big Box Retail Buildings - 50% Energy Savings

Energy Technology Data Exchange (ETDEWEB)

Bonnema, E.; Leach, M.; Pless, S.

2013-06-01

This Technical Support Document describes the process and methodology for the development of the Advanced Energy Design Guide for Medium to Big Box Retail Buildings: Achieving 50% Energy Savings Toward a Net Zero Energy Building (AEDG-MBBR) ASHRAE et al. (2011b). The AEDG-MBBR is intended to provide recommendations for achieving 50% whole-building energy savings in retail stores over levels achieved by following ANSI/ASHRAE/IESNA Standard 90.1-2004, Energy Standard for Buildings Except Low-Rise Residential Buildings (Standard 90.1-2004) (ASHRAE 2004b). The AEDG-MBBR was developed in collaboration with the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE), the American Institute of Architects (AIA), the Illuminating Engineering Society of North America (IES), the U.S. Green Building Council (USGBC), and the U.S. Department of Energy.

Max Auwaerter symposium: spin mapping and spin manipulation on the atomic scale

International Nuclear Information System (INIS)

Wiesendanger, R.

2008-01-01

Full text: A fundamental understanding of magnetic and spin-dependent phenomena requires the determination of spin structures and spin excitations down to the atomic scale. The direct visualization of atomic-scale spin structures has first been accomplished for magnetic metals by combining the atomic resolution capability of Scanning Tunnelling Microscopy (STM) with spin sensitivity, based on vacuum tunnelling of spin-polarized electrons. The resulting technique, Spin-Polarized Scanning Tunnelling Microscopy (SP-STM), nowadays provides unprecedented insight into collinear and non-collinear spin structures at surfaces of magnetic nanostructures and has already led to the discovery of new types of magnetic order at the nanoscale. More recently, the development of subkelvin SP-STM has allowed studies of ground-state magnetic properties of individual magnetic adatoms on non-magnetic substrates as well as the magnetic interactions between them. Based on SP-STM experiments performed at temperatures of 300 mK, indirect magnetic exchange interactions at the sub-milli-electronvolt energy scale between individual paramagnetic adatoms as well as between adatoms and nearby magnetic nanostructures could directly be revealed in real space up to distances of several nanometers. In both cases we have observed an oscillatory behavior of the magnetic exchange coupling, alternating between ferromagnetic and antiferromagnetic, as a function of distance. Moreover, the detection of spin-dependent exchange and correlation forces has allowed a first direct real-space observation of spin structures at surfaces of antiferromagnetic insulators. This new type of scanning probe microscopy, called Magnetic Exchange Force Microscopy (MExFM), offers a powerful new tool to investigate different types of spin-spin interactions based on direct-, super-, or RKKY-type exchange down to the atomic level. By combining MExFM with high-precision measurements of damping forces, localized or confined spin

Inter-satellite calibration of FengYun 3 medium energy electron fluxes with POES electron measurements

Science.gov (United States)

Zhang, Yang; Ni, Binbin; Xiang, Zheng; Zhang, Xianguo; Zhang, Xiaoxin; Gu, Xudong; Fu, Song; Cao, Xing; Zou, Zhengyang

2018-05-01

We perform an L-shell dependent inter-satellite calibration of FengYun 3 medium energy electron measurements with POES measurements based on rough orbital conjunctions within 5 min × 0.1 L × 0.5 MLT. By comparing electron flux data between the U.S. Polar Orbiting Environmental Satellites (POES) and Chinese sun-synchronous satellites including FY-3B and FY-3C for a whole year of 2014, we attempt to remove less reliable data and evaluate systematic uncertainties associated with the FY-3B and FY-3C datasets, expecting to quantify the inter-satellite calibration factors for the 150-350 keV energy channel at L = 2-7. Compared to the POES data, the FY-3B and FY-3C data generally exhibit a similar trend of electron flux variations but more or less underestimate them within a factor of 5 for the medium electron energy 150-350 keV channel. Good consistency in the flux conjunctions after the inter-calibration procedures gives us certain confidence to generalize our method to calibrate electron flux measurements from various satellite instruments.

Low-energy spin fluctuations in the non-Fermi-liquid compound YbRh2Si2

Directory of Open Access Journals (Sweden)

O. Stockert et al

2007-01-01

Full Text Available We report on inelastic neutron scattering experiments on YbRh2Si2 powder to study the low-energy spin dynamics at temperatures between T=0.8 and 22 K. The low-energy magnetic response is quasielastic. However, it exhibits an unusual form not modelled by a simple relaxation rate yielding a Lorentzian lineshape, but can satisfactorily be described by a phenomenological model involving a distribution of relaxation rates. The lower bound of the relaxation rates varies roughly linear with temperature indicating a pronounced slowing down of the critical modes above the antiferromagnetic ordering temperature TNapprox70 mK.

One and two-phonon processes of the spin-flip relaxation in quantum dots: Spin-phonon coupling mechanism

Science.gov (United States)

Wang, Zi-Wu; Li, Shu-Shen

2012-07-01

We investigate the spin-flip relaxation in quantum dots using a non-radiation transition approach based on the descriptions for the electron-phonon deformation potential and Fröhlich interaction in the Pavlov-Firsov spin-phonon Hamiltonian. We give the comparisons of the electron relaxations with and without spin-flip assisted by one and two-phonon processes. Calculations are performed for the dependence of the relaxation time on the external magnetic field, the temperature and the energy separation between the Zeeman sublevels of the ground and first-excited state. We find that the electron relaxation time of the spin-flip process is more longer by three orders of magnitudes than that of no spin-flip process.