摘要:

Recent results involving spin-exchange optical pumping are reviewed, particularly as they pertain to polarized3Hetargets. Included are recent measurements of relevant spin-exchange parameters, operational experience running the polarized3Hetarget that was used for SLAC E154, and a discussion of the polarized3Hetarget currently being constructed for TJNAF. ©1998 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.54962

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

The HERMES experiment uses an internal target in the HERA positron ring at DESY to study polarized inclusive and semi-inclusive deep inelastic scattering processes. Several light nuclei will be used to disentangle the contributions of protons and neutrons. In 1995 HERMES used an optically pumped metastability exchange3Hetarget. This target is described in this paper, with emphasis on the specific adaptations to the HERMES experiment. ©1998 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.54963

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

Quasi-elastic electron scattering may provide precise information on theS′and the D-wave parts of the3Heground-state wave function, the neutron form factors, and the ro⁁le of spin-dependent reaction mechanism effects. An experiment is being performed at the AmPS storage ring at NIKHEF (Amsterdam, the Netherlands), where polarized electrons (up to 900 MeV) are used in combination with large acceptance electron and hadron detectors. Preliminary results from data at four-momentum transfer squaredQ2=0.15 GeV2are presented. ©1998 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.54964

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

The neutron electric form factorGEnhas been measured at the cw electron accelerator MAMI in the double polarized exclusive reactions3H&vec;e(e&vec;,e′n)andD(e&vec;,e′n&vec;)in quasi elastic kinematics with one common detector system. Experimental set-up and analysis of a3H&vec;e(e&vec;,e′n)-measurement in the range of momentum transferQ2=0.27−0.5 (GeV/c)2are discussed in this article. For events with low missing momentum(|P&vec;m|⩽100 MeV/c)the PWIA analysis yieldsGEn=0.0352±0.0033±0.0024with statistical and systematical error, corresponding to a quadratically added total error of 11.6&percent; relativ. This result will be compared with preliminary results obtained from theD(e&vec;,e′n&vec;)-reaction and with data from elasticD(e,e′)scattering. ©1998 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.55012

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

In the frame of the A1-Collaboration at the Mainz Microtron a test measurement of doubly polarized3H&vec;e(e&vec;,e′n)scattering from a high pressure target was performed in July aiming for the determination of the neutron electric form factorGenat high momentum transfer(Q2=0.7(GeV/c)2).Due to the small value ofGencompared toGmna preferred procedure is to determine the asymmetry in the exclusive quasi elastic scattering of polarized electrons (P≈70&percent;,I⩾2&mgr;A) from polarized3H&vec;e.The scattered electrons are detected in a high resolution magnetic spectrometer while the scattering angles of the outgoing neutrons are measured in a plastic scintillator. In this reaction the polarized3H&vec;enucleus serves as an effective polarized neutron target. Because of the large magnetic field gradients caused by the spectrometer and limited space at the target place, the3H&vec;egas is polarized elsewhere and transported to the target place in specially prepared glass cells. The glass cells are designed for high pressure (up to 10 bar) and with thin windows to prevent background. To reduce the relaxation due to the magnetic field gradients a &mgr;-metal shielded guiding field of 4 Gauss is used. The guiding field is generated by three independent coils which permit the rotation of the target spin in any direction desired, especially perpendicular and parallel with respect toq&vec;.So we are able to take the ratio of the asymmetriesA⊥/A∥,which in first order depends only on kinematical factors and the ratioGen/Gmn.The method of metastable optical pumping is used to polarize the3H&vec;eat about 1 mbar with a LNA laser(≈6W).Subsequently the gas is compressed by means of a two-stage-piston compressor up to 6 bar with a polarization of roughly 45&percent;. ©1998 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.55014

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

We describe the NMR and Rb Zeeman frequency shift polarimeters used for determining the3Hepolarization in a recent precision measurement of the neutron spin structure functiong1at SLAC (E-154). We performed a detailed study of the systematic errors associated with the calibration of the NMR polarimeter. A new technique was used for determining the3Hepolarization from the frequency shift of the Rb Zeeman resonance. ©1998 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.54965

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

We describe two polarimetry techniques used in the HERMES experiment. They are both based on the principle of measuring the rate and circular polarization of photons emitted from excited states of target atoms and can be used together to directly access information regarding the target atoms which interact with the beam. ©1998 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.55015

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

A brief review of the International Workshop on Polarized3HeBeams and Gas Targets and Their Application (HELION97), which was held from 20th through 24th January, 1997 in Kobe, Japan, is presented paying particular attention to the highlights from the workshop. Since topics of the workshop covered almost all of the fields related to polarized3Heand its surroundings, i.e., from particle physics to medical applications, this was really the first meeting through which we could comprehensively discuss a variety of problems raised in the individual field on the common ground. In this respect, the subtitle,from Quark to Lifeseems to hit the mark as another title of HELION97. ©1998 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.54983

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

The HERMES polarized hydrogen target is an internal gas target using the storage cell technique. It was installed in the HERA ring at DESY during the 1996 winter shutdown and has been used throughout the 1996 and 1997 running periods. The major components of the target and its operating parameters are described. The performance during data taking is presented along with some studies of the target cell surface. Evidence suggests that the effective HERMES target cell coating is a saturated layer of water on top of the Drifilm coating. ©1998 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.55016

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

We describe the polarized deuterium target internal to the NIKHEF medium-energy electron storage ring. Tensor polarized deuterium was produced in an atomic beam source and injected into a storage cell target. A Breit-Rabi polarimeter was used to monitor the injected atomic beam intensity and polarization. An electrostatic ion-extraction system and a Wien filter were utilized to measure on-line the atomic fraction of the target gas in the storage cell. This device was supplemented with a tensor polarization analyzer using the neutron anisotropy of the3H(d,n)&agr;reaction at 60 keV. This method allows determining the density-averagednuclearpolarization of the target gas, independent ofspatialandtemporalvariations. We address issues important for polarized hydrogen/deuterium internal targets, such as the effects of spin-exchange collisions and resonant transitions induced by the RF fields of the charged particle beam. ©1998 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.54984

出版商:AIP    

年代:1998

数据来源: AIP