标题： 中子捕获反应中的宇称不守恒 显示英文标题

标题： Parity Violation in Neutron Capture Reactions

摘要： 在过去十年中，极化中子在复合核共振上的散射被证明是一种强大的实验技术，用于探测核宇称不守恒。 在诸如$^{139}$La 和$^{232}$Th 等核的 p 波共振的中子透射测量中，纵向分析功率被发现高达 10%。 在这里，我们检查在这些相同的复合核共振上进行平行程序以测量$(n,\gamma$) 反应不对称性的可能性。 对称性破坏的$(n,\gamma$) 研究也可以显示出高达 10% 的不对称性，并且相比于透射实验，其优势在于可以从同一共振中不同的伽马衰变分支中观察到宇称奇的不对称性。 因此，例如，在洛斯阿拉莫斯卢赞设施使用高效率的锗探测器研究$(n,\gamma)$ 反应中的宇称不守恒，可以高精度地确定复杂核中的宇称奇核子-核子矩阵元。 此外，同时研究涉及这些衰变的 E1 和$V_{PNC}$ 矩阵元可以用来帮助约束复合核中宇称不守恒的统计理论。 显示英文摘要

摘要： In the last decade, the scattering of polarized neutrons on compound nucleus resonances proved to be a powerful experimental technique for probing nuclear parity violation. Longitudinal analyzing powers in neutron transmission measurements on p-wave resonances in nuclei such as $^{139}$La and $^{232}$Th were found to be as large as 10%. Here we examine the possibilities of carrying out a parallel program to measure asymmetries in the $(n,\gamma$) reaction on these same compound nuclear resonances. Symmetry-violating $(n,\gamma$) studies can also show asymmetries as large as 10%, and have the advantage over transmission experiments of allowing parity-odd asymmetries in several different gamma-decay branches from the same resonance. Thus, studies of parity violation in the $(n,\gamma)$ reaction using high efficiency germanium detectors at the Los Alamos Lujan facility, for example, could determine the parity-odd nucleon-nucleon matrix elements in complex nuclei with high accuracy. Additionally, simultaneous studies of the E1 and $V_{PNC}$ matrix elements invol ved in these decays could be used to help constrain the statistical theory of parity non-conservation in compound nuclei.