Research on Violation of Space-Time Symmetires with Slow Neutrons

强子相互作用中奇偶违反过程的研究有助于获得强子间弱味守恒力的信息。在质量数为-100的几个低能（n. γ）反应中研究了宇称非守恒效应。纵波共振测量了纵向不对称性（A_L）。它被发现与伽马射线能量阈值无关。测量了^<81>Br, ^<93>Nb, ^<108>Pd, ^<111>Cd, ^<124>Sn和^<139>La的A值。对于^<139>La （E_n=0.734 eV）、^<81>Br（E_n=0.88 eV）和^<111>Cd(E_n=4.53 eV)，得到的非零值分别为A_L=(9.8 0.3)%、（2.1 0.1）%和-(1.3+0.7-0.4)%。这些结果可以用入射中子的s波和p波两个振幅之间的干涉来解释。σ^ ^ * _n”。还测量了^<139>La的K^^*_<伽玛>校正项。结果表明在单次伽马射线跃迁中存在出口-通道奇偶混合。此外，我们还进行了测量中子自旋自旋与^<139>La核相互作用的测试。发现在p波共振区可以观察到宇称破坏效应。对于t违和实验，中子自旋、中子动量和靶核自旋之间必须观察到三重相关。我们在laf3和laa10_3晶体中发现了相当大的^<139>La极化。这是t违和度测量的第一步。利用激光束进行了^3He和质子在室温下的极化实验。这对今后中子偏振器和偏振分析仪的研制具有重要的指导意义。

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.