论文标题
239PU的391.6 keV亚稳态水平的半衰期的高精度测量
High precision measurement of the half-life of the 391.6 keV metastable level in 239Pu
论文作者
论文摘要
稀有事件物理的材料选择需要高性能检测器和自定义分析。在这种情况下，开发了一种新型的$β$ - $γ$检测系统，该系统由液体闪烁体与HPGE巧合，主要目的是研究液体样品中铀，or和钾的超痕量污染。 In the search for $^{238}\textrm{U}$ contaminations through neutron activation analysis, since the activation product $^{239}\textrm{Np}$ decays to a relatively long-lived isomeric state of $^{239}\textrm{Pu}$, it is possible to perform a time selection of these events obtaining a strong background suppression.调查$β^ - $ np of $^{239} \ textrm {np} $与延迟事件的$β^ - $衰减之间的时间分布，并在$^{239} \ textrm {pu} $^{239} \ textrm {pu} $ isomeric级别的391.6 kev中，以391.6 kev的高度测量为一半的级别，该级别是该级别的一半。 391.6 kev $^{239} \ textrm {pu} $级别的半衰期导致$ 190.2 \ pm 0.2 $ ns，因此，与以前的测量相比，精度提高了约20倍。
Materials selection for rare event physics requires high performance detectors and customized analyses. In this context a novel $β$-$γ$ detection system, comprised of a liquid scintillator in coincidence with a HPGe, was developed with the main purpose of studying ultra trace contamination of uranium, thorium and potassium in liquid samples. In the search for $^{238}\textrm{U}$ contaminations through neutron activation analysis, since the activation product $^{239}\textrm{Np}$ decays to a relatively long-lived isomeric state of $^{239}\textrm{Pu}$, it is possible to perform a time selection of these events obtaining a strong background suppression. Investigating the time distribution of the coincidences between the $β^-$ decay of $^{239}\textrm{Np}$ and the delayed events following the de-excitation of the $^{239}\textrm{Pu}$ isomeric level at 391.6 keV, a precision measurement of the half-life of this level was conducted. The half-life of the 391.6 keV $^{239}\textrm{Pu}$ level resulted $190.2 \pm 0.2$ ns, thus increasing the precision by about a factor of 20 over previous measurements.
