1992 Fiscal Year Final Research Report Summary
Research on Violation of Space-Time Symmetires with Slow Neutrons
| Project/Area Number |
01420003
|
|---|
| Research Category |
Grant-in-Aid for General Scientific Research (A)
|
| Allocation Type | Single-year Grants |
|---|
| Research Field |
核・宇宙線・素粒子
|
|---|
| Research Institution | KYOTO UNIVERSITY |
|---|
Principal Investigator |
MASAIKE Akira Kyoto Univ. Fac.of Science Professor, 理学部, 教授 (40022587)
|
|---|
| Co-Investigator(Kenkyū-buntansha) |
MASUDA Yasuhiro National Lab. High Energy Physics Research Assistant, 助手 (60150009)
ENYO Hideto Kyoto Univ. Fac.of Science Research Assistant, 理学部, 助手 (30213606)
IMAI Kenichi Kyoto Univ. Fac.of Science Associate Prof., 理学部, 助教授 (70025493)
|
|---|
| Project Period (FY) |
1989 – 1992
|
| Keywords | Parity / Time Reversal / Resonance Abosrption / La nucleus / Hilicity Asymmetry / Epithermal Neutron |
|---|
| Research Abstract |
The study of parity-violating processes in hadronic interactions is useful to obtain information on the weak flavor conserving force between hadrons.
The parity non-conserving effect was investigated in low energy (n.gamma) reactions for several nuclei with mass number of -100. The longitudinal asymmetries (A_L) were measured in p-wave resonances. It was found to be independent of the gamma-ray energy thresholds. The A 's were measured for the targets of ^<81>Br, ^<93>Nb, ^<108>Pd, ^<111>Cd, ^<124>Sn and ^<139>La. The obtained non-zero values are A_L=(9.8 0.3)%, (2.1 0.1)% and -(1.3+0.7-0.4)% for ^<139>La (E_n=0.734 eV), ^<81>Br(E_n=0.88 eV) and ^<111>Cd(E_n=4.53 eV), respectively. The results can be explained in terms of the interference between two amplitudes of s- and p-wave incident neutrons.
The sigma^^*_n.K^^*_<gamma> correction term for ^<139>La has been also measured. The result suggests the existence of exit-channel parity-mixing in a single gamma-ray transitions.
In addition, we have carried out a test of the measurement of the neutron spin rotation due to the interaction with the ^<139>La nuclei. It was found that the parity violation effect could be observed in the p-wave resonance region. For T-violation experiments, a triple correlation among the neutron spin, the neutron momentum and the target nuclear spin has to be observed. We have found sizable polarization of ^<139>La in crystals of LaF_3and LaA1O_3. It is the first step of the T-violation measurement.
Polarization experiments of the ^3He and the proton in room temperature have been carried out using laser beams. These are quite useful for the polarizer and the polarization analyzer of neutrons in future.
|
