Studies on the wave property of neutron and its application to the measurements of space-time symmetries

(1)研究了中子反应宇称破坏效应大幅增强的原因。首先，在LANSCE上测量了几个中重核在几百eV到2 KeV的p波共振中中子的核吸收的纵向不对称性。通过对实验数据的分析，计算了反应弱矩阵的色散，并推导出平均弱扩散宽度（I'w）为（0.5^^+_ -0.3）× 10^<-7> eV。我们还测量了^<139>La的0.734 ev p波共振中中子的宇称非守恒自旋。旋转角度确定为（7.4^^+_ -1.1）× 10^<-3>rad./cm。结果与s-p混合模型的预测结果吻合较好。(2)首次测量了固体氘中超冷中子的生存时间。这一关键参数对利用固体邻氘作为源材料的超热UCN源的有效性提供了基本限制。(3)研究了圆柱形环空慢化池冷中子源的自调节。仿真结果表明，即使在总热负荷扰动较大的情况下，缓冲罐压力和慢化槽内液位也保持稳定。(4)在两个中子自旋态之间插入不同的Ni_<25> Ti_<75>功率样品，观察到自旋干涉的退相干现象。采用机械合金化法制备了不同铣削时间的试样。我们发现通过增加合金化时间可以提高能见度。

(1) Origin of large enhancement of the parity violation effect in neutron reactions has been investigated. First, the longitudinal asymmetries is nuclear absorptions of neutrons in p-wave resonances has been measured for several medium and heavy nuclei at LANSCE in the energy of several hundred eV to 2 KeV. We have analyzed the data to calculate the dispersion of weak matrix of the reactions and have deduced the average weak spreading width (I'w) to be (0.5^^+__-0.3) × 10^<-7> eV. We have measured also the parity non-conserving spin rotation of neutrons in the 0.734-eV p-wave resonance of ^<139>La. The rotation angle was determined to be (7.4^^+__-1.1) × 10^<-3>rad./cm. The results agree well with the prediction of the s-p mixing model.(2) The measurements of the survival time of ultra-cold neutrons in solid deuterium have been made for the first time. This critical parameter provides fundamental limitation to the effectiveness of super-thermal UCN sources that utilize solid ortho-deuterium as the source material.(3) Self regulation of the cold neutron source with a cylindrical annulus moderator cell has been investigated. The simulation shows us that the buffer tank pressure and the liquid level in the moderator cell are stable even against large disturbance of the total heat load.(4) We have observed decoherent phenomena in spin interference in between two neutron spin states inserting several different Ni_<25> Ti_<75> power samples. The samples have been made by Mechanical Alloying Method with different milling time. We have found an improvement of the visibility by increasing their alloying time.