Polarized high pressure {sup 3}H-vectore target at MAMI

Journal Article · Tue Jan 20 04:00:00 EST 1998 · AIP Conference Proceedings

DOI:https://doi.org/10.1063/1.55014· OSTI ID:21182449

Rohe, Daniela; Becker, J; Bermuth, J; Deninger, A; Ebert, M; Grossmann, T; Lauer, L; Otten, E W; Rohe, D; Surkau, R ^[1]; Bartsch, P; Baumann, D; Boehm, R; Caprano, T; Clawiter, N; Derber, S; Ding, M; Distler, M; Ebbes, A; Ewald, I ^[2]

---

1. Institut fuer Physik, Universitaet Mainz, D-55099 Mainz (Germany)
2. Institut fuer Kernphysik, Universitaet Mainz, D-55099 Mainz (Germany)

In the frame of the A1-Collaboration at the Mainz Microtron a test measurement of doubly polarized {sup 3}H-vectore(e-vector,e{sup '}n) scattering from a high pressure target was performed in July aiming for the determination of the neutron electric form factor G{sub en} at high momentum transfer (Q{sup 2}=0.7(GeV/c){sup 2}). Due to the small value of G{sub en} compared to G{sub mn} a preferred procedure is to determine the asymmetry in the exclusive quasi elastic scattering of polarized electrons (P{approx_equal}70%, I{>=}2{mu}A) from polarized {sup 3}H-vectore. 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 polarized {sup 3}H-vectore nucleus 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, the {sup 3}H-vectore gas 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 {mu}-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 to q-vector. So we are able to take the ratio of the asymmetries A{sub perpendicular}/A{sub parallel}, which in first order depends only on kinematical factors and the ratio G{sub en}/G{sub mn}. The method of metastable optical pumping is used to polarize the {sup 3}H-vectore at about 1 mbar with a LNA laser ({approx_equal}6W). Subsequently the gas is compressed by means of a two-stage-piston compressor up to 6 bar with a polarization of roughly 45%.

• OSTI ID: 21182449
• Journal Information: AIP Conference Proceedings, Journal Name: AIP Conference Proceedings Journal Issue: 1 Vol. 421; ISSN APCPCS; ISSN 0094-243X
• Country of Publication: United States
• Language: English

Related Subjects

73 NUCLEAR PHYSICS AND RADIATION PHYSICS
ASYMMETRY
ELECTRON BEAMS
ELECTRON REACTIONS
ELECTRONS
FOUR MOMENTUM TRANSFER
GEV RANGE
MAGNETIC FIELDS
MAGNETIC SPECTROMETERS
NEUTRONS
OPTICAL PUMPING
POLARIZATION
POLARIZED BEAMS
POLARIZED TARGETS
QUASI-ELASTIC SCATTERING
RELAXATION
SPIN
TRITIUM TARGET