Precise measurement of gamma ray emission probability by using a live-timed bi-dimensional data acquisition system

1.采用高纯锗探测器和4pibeta加压正比计数器，利用实时二维数据采集系统测量伽马射线发射几率。用该系统测量了~(60)Co和~(134)Cs的解体速率，结果与常规方法一致。利用二维效率外推法可以很容易地测量电子俘获衰变的^&lt；57&gt；Co的解体速率。为了确定伽马射线探测效率，测量了~(152)Eu和~(152)Eu的崩解率。Eu的衰变是通过β粒子发射和电子俘获伴随相当一部分的转换电子，这使标准化变得复杂，但可以通过二维效率外推法确定准确的解体速率。~(133)Ba的崩解率对栅极…的影响不大。更多设置在47pibeta-伽马符合计数中，使用NaI(T1)闪烁体。其原因可能是大的内转换电子而不是53keV的伽马射线，因此采用了二维效率外推方法。5种伽玛射线组合效果较好。确定了^&lt；42&gt；K的1.52 MeV伽马射线的发射几率为0.1808&lt；正负&0.0009。目前的结果的不确定度比过去的结果小两倍，这足以考虑^&lt；42&gt；K的应用，它可以从^&lt；42&gt；Ar.6“挤奶”。~lt；86&>Rb以约0.9的几率直接跃迁到^&lt；86&>sr的地面能级，从激发能级发出的1077keV的伽马射线是在以约0.1的几率发射β射线后发射的。为了确定伽马射线的发射概率，需要测量β分支比或崩解率和伽马射线强度。本工作对1077keV伽马射线的发射几率给出了较好的结果，正负0.00003.7。~(103)Ru的大量跃迁经历了半衰期为56min的40keV亚稳态能级，且跃迁具有较大的内转换系数。存在一个关于存在到40keV能级或基态的贝塔跃迁的问题。目前对497keV伽马射线发射几率的计算结果表明，到地面能级的β跃迁为0.0072&lt；正负&0.0062，而到40keV能级的β跃迁为零。较少

1. A high purity germanium detector and a 4pibeta pressurized proportional counter using a live-timed bi-dimensional data acquisition system were used for measurement of gamma-ray emission probability.2. When the disintegration rate of ^<60>Co and ^<134>Cs, which decay by beta^- particle emission, were measured by this system, the results agreed with those measured by conventional method. The disintegration rate of ^<57>Co which decays by electron capture can be easily measured by application of two-dimensional efficiency extrapolation method.3. Measurement of disintegration rate for ^<152>Eu was carried out for determination of gamma-ray detection efficiency. ^<152>Eu decays via beta^- -particle emission and electron capture accompanied by a substantial fraction of conversion electrons, which complicate standardization, but accurate disintegration rate can be determined by two-dimensional efficiency extrapolation method.4. Disintegration rate of ^<133>Ba depended slightly on the gate … More set in the 47pibeta-gamma coincidence counting using a NaI(T1) scintillator. The reason is probably large internal conversion electrons instead of the 53 keV gamma-rays; therefore, two-dimensional efficiency extrapolation method was applied. Five combinations of gamma-rays gave good results.5. The emission probability for the 1.52 MeV gamma-ray of ^<42>K was determined to be 0.1808<plus-minus>0.0009. The present result has an uncertainty smaller than the past results by factor of two, and that is small enough to consider the application of ^<42>K which can be "milked" from ^<42>Ar.6. ^<86>Rb transits directly to the ground level of ^<86>Sr with probability of about 0.9, and the 1077 keV gamma-ray from the excited level is emitted following emission of beta-ray with about 0.1 of emission probability. To determine the emission probability of the gamma-ray, it is required the measurement of beta branching ratio or of the disintegration rate and gamma-ray intensity. The present work showed the good result for the emission probability of the 1077 keV gamma-ray, O.0888<plus-minus>O.0003.7. A large amount transition from ^<103>Ru go through the 40 keV metastable level that has half-life of 56 min and the transition has a large internal conversion coefficient. There is a problem concerning with existence of beta transition to the 40 keV level or ground level. The present result for emission probability for the 497 keV gamma-ray showed that the beta transition to the ground level is 0.0072<plus-minus>0.0062 and that the beta transition to the 40 keV level is nothing. Less