摘要 :
The Leggett-Rice effect in liquid He-3 was proposed on the basis of Fermi liquid interactions of the He-3 quasiparticles. Consideration of the interparticle interactions in polarised gaseous He-3 led, similarly, to spin rotation e...
展开
The Leggett-Rice effect in liquid He-3 was proposed on the basis of Fermi liquid interactions of the He-3 quasiparticles. Consideration of the interparticle interactions in polarised gaseous He-3 led, similarly, to spin rotation effects describable by a Leggett-Rice equation. In spin polarised solid He-3 an analogous effect has been proposed from a consideration of the inter-nuclear exchange interaction. We show, in this paper, that spin rotation behaviour of the Leggett-Rice type in all these systems may be understood as a consequence of symmetry constraints. (C) 2000 Elsevier Science B.V. All rights reserved. [References: 2]
收起
摘要 :
Polarized Small Angle Neutron Scattering (SANS) is a powerful tool for studying mesoscale magnetic structures. In a recent development at the Oak Ridge National Laboratory (ORNL), a polarized neutron beam has been implemented for ...
展开
Polarized Small Angle Neutron Scattering (SANS) is a powerful tool for studying mesoscale magnetic structures. In a recent development at the Oak Ridge National Laboratory (ORNL), a polarized neutron beam has been implemented for the CG-2 (GP-SANS) beamline at the High Flux Isotope Reactor (HFIR). Three major components were developed to provide the polarized neutron capability: a transmission supermirror neutron polarizer, an adiabatic fast passage neutron spin flipper and a polarized He-3 filter as neutron spin analyzer. The new polarized beam SANS capability was used to investigate several magnetic samples having mesoscale structures.
收起
摘要 :
Cesiated cells made out of quartz glass are widely used as vessels for hyperpolarised He-3 to be applied in neutron scattering experiments. In spite of the significant progress achieved in the enhancement of the relaxation times, ...
展开
Cesiated cells made out of quartz glass are widely used as vessels for hyperpolarised He-3 to be applied in neutron scattering experiments. In spite of the significant progress achieved in the enhancement of the relaxation times, the crucial mechanisms of spin-wall interaction are not really understood and spin filter cells still suffer from a worse reproducibility regarding their relaxation behaviour.We report the first experimental observation of a T, dependence on the magnetic history in uncoated as well as in cesiated cells made out of quartz glass. A huge decrease (about one order of magnitude) of the relaxation time constant T, occurred solely due to short exposure of the cells to an external magnetic field of 0.7 T. Partial or total restoring of the initial relaxation time constant T, could be achieved by a careful degaussing of the magnetised cells. The magnetisation turned out to be very stable in time, keeping T-1 unmodified during a few months or even years. The relaxation time T, was measured directly in the neutron beam from the decay of the polarised neutron flipping ratio. The cell preparation procedures are also presented. (C) 2004 Elsevier B.V. All rights reserved.
收起
摘要 :
As there are no free neutron targets one has to resort to the nuclear targets deuterium or helium. In order to reduce nuclear effects blurring the information on nuclear form factors the technique of double polarization experiment...
展开
As there are no free neutron targets one has to resort to the nuclear targets deuterium or helium. In order to reduce nuclear effects blurring the information on nuclear form factors the technique of double polarization experiments had been developed. Recent experiments at MAMI measuring the electric form factor of the neutron are discussed. In addition, other single and double nucleon knockout experiments are described which support the buildup of a consistent interpretation of nuclear structure in 3He.
收起
摘要 :
We report the first measurements of the specific heat of highly polarized liquid He-3. The specific heat is observed to decrease with increasing polarization. Our results, which agree with a quadratic extrapolation of the low pola...
展开
We report the first measurements of the specific heat of highly polarized liquid He-3. The specific heat is observed to decrease with increasing polarization. Our results, which agree with a quadratic extrapolation of the low polarization behaviour deduced from the temperature dependence of the magnetic susceptibility through Maxwell's relation, are in contradiction with Vollhardt's 'nearly solid' model of liquid He-3. (C) 2000 Elsevier Science B.V. All rights reserved. [References: 4]
收起
摘要 :
The search for particle electric dipole moments (EDM's) is one of the best places to look for physics beyond the standard model of electroweak interaction because the size of time reversal violation predicted by the standard model...
展开
The search for particle electric dipole moments (EDM's) is one of the best places to look for physics beyond the standard model of electroweak interaction because the size of time reversal violation predicted by the standard model is incompatible with present ideas concerning the creation of the baryon-antibaryon asymmetry. As the sensitivity of these EDM searches increases more subtle systematic effects become important. We develop a general analytical approach to describe a systematic effect recently observed in an electric dipole moment experiment using stored particles [J. M. Pendlebury , Phys. Rev. A 70, 032102 (2004)]. Our approach is based on the relationship between the systematic frequency shift and the velocity autocorrelation function of the resonating particles. Our results, when applied to well-known limiting forms of the correlation function, are in good agreement with both the limiting cases studied in recent work that employed a numerical and heuristic analysis. Our general approach explains some of the surprising results observed in that work and displays the rich behavior of the shift for intermediate frequencies, which has not been studied previously.
收起
摘要 :
A neutron polarizer-analyzer system based on polarized ~3He is being developed at KEK Pulsed Neutron Source for an experiment on time reversal invariance in the nuclear reaction at J-PARC.
摘要 :
We present measurements of the magnetic relaxation of highly polarized liquid He-3 confined inside a silver sinter, from 40 mK to 1.15 K, and 2 to 27 bars. At low temperature, the relaxation rate decreases with increasing polariza...
展开
We present measurements of the magnetic relaxation of highly polarized liquid He-3 confined inside a silver sinter, from 40 mK to 1.15 K, and 2 to 27 bars. At low temperature, the relaxation rate decreases with increasing polarization, in qualitative agreement with the Hammel-Richardson model. In this framework, our results at low polarization imply that relaxation in the first, solid, layer does not depend on pressure, but is more efficient as the temperature increases. (C) 2000 Elsevier Science B.V. All rights reserved. [References: 5]
收起
摘要 :
Glass cells play an important role in polarized ~3He neutron spin filters. To evaluate the scattering and absorption contribution from glass cells during neutron scattering experiments, we measured small-angle scattering and neutr...
展开
Glass cells play an important role in polarized ~3He neutron spin filters. To evaluate the scattering and absorption contribution from glass cells during neutron scattering experiments, we measured small-angle scattering and neutron transmission in GE180 and other glasses. The small-angle neutron scattering measurements revealed that the glasses used for ~3He spin filters have acceptably lower scattering: dΣ(Q)/dΩ=47×10 ~(-4) cm~(-1) at Q=0.030.12 ?~(-1). The transmission measurement was performed at J-PARC. Neutron transmission of about 92% through empty GE180 cells was observed over a wide wavelength range 0.0147.0 ?. To pursue the possibility of being a structural influence on ~3He spin relaxation in GE180 glass cells, we performed precise X-ray diffraction measurement using synchrotron radiation at SPring-8. From these measurements, a structural difference was observed among GE180 glasses with different thermal treatments.
收起
摘要 :
Finely dispersed carbonizate powders were studied with the aim of revealing their suitability for producing hyperpolarized noble gases. In the temperature and frequency dependences obtained over a wide range of temperatures and ma...
展开
Finely dispersed carbonizate powders were studied with the aim of revealing their suitability for producing hyperpolarized noble gases. In the temperature and frequency dependences obtained over a wide range of temperatures and magnetic fields for the spin-lattice relaxation times of the magnetic moments of He-3, H-1, and C-13 nuclei, anomalous features caused by the suppression of the exchange between surface paramagnetic centers in a magnetic field were observed. It is shown that the interaction with magnetic moments of the H-1 nuclei situated near the paramagnetic centers is the main polarization-leakage channel for the noble-gas nuclear spins. (C) 2004 MAIK "Nauka / Interperiodica".
收起
原文获取