Precise Measurement of γ-ray Emission Probabilities for Br-80 and Ru-105

在KURRI，通过热中子辐照富集Na^<79>Br（富集度为99.41%）和^<104>Ru（富集度为99.21%）金属粉末产生^<80,80m>Br和^<105>Ru。在含悬浮粉末的HCl溶液中制备了金属化VYNS薄膜的绝对测量源，采用二维数据采集系统，用4πβ-γ(HPGe)符合仪测量了其崩解速率和γ射线强度。在每个系列的测量中，通过标准源^<24>Na,^<57>Co,^<60>Co,^<133>Ba,^<134>Cs和^<152>Eu来校准HPGe探测器的γ射线探测效率。这些辐射源是用放射性溶液制备的，用同样的仪器测量。^<80m>Br （4.42 h）的内部转换电子对^<80>Br （17.68 m）的衰变速率测量有影响，^<24>Na （14.965 h）的β射线也在4πβ计数器中计数。另一方面，^<105>Ru的子元素^<105>Rh通过β粒子发射衰变，半衰期为35.36 h，因此在测量和数据处理中需要引起各种注意。^<80>Br的616.3 keV γ射线发射概率为6.14±0.05%，比先前报道的6.7±0.6%大了约10%。^<105>Ru的数据与不确定度内的评估值一致，但强γ射线的不确定度从3%大大提高到0.6%。而相对湿度<105>时，306.1 keV和318.9 keV的评价值分别为4.76±0.05%和16.99±0.17%,5.1±0.6%和19.1±0.6%的评价值高出约10%。

Sources of ^<80,80m>Br and ^<105>Ru were produced by thermal neutron irradiation of enriched Na^<79>Br (enrichment:99.41%) and ^<104>Ru (99.21%) metal powder at KURRI. Sources for absolute measurement were prepared on metallized VYNS films from HCl solution containing the suspended powder, and the disintegration rates and the γ-ray intensities were measured by a 4πβ-γ(HPGe) coincidence apparatus using a two-dimensional data-acquisition system. The γ-ray detection efficiencies for the HPGe detector were calibrated in each series of measurements by standard sources of ^<24>Na,^<57>Co,^<60>Co,^<133>Ba,^<134>Cs and ^<152>Eu. These sources were prepared from radioactive solution and measured by the same apparatus.The internal conversion electrons from ^<80m>Br (4.42 h) affect for disintegration rate measurement of ^<80>Br (17.68 m), and the β-rays from ^<24>Na (14.965 h) are also counted in the 4πβ-counter. On the other hand, ^<105>Rh, daughter of ^<105>Ru, decays by β-particle emission with half-life of 35.36 h. Therefore, it was necessary various attention in the measurements and data treatments.The γ-ray emission probability of 616.3 keV for ^<80>Br was 6.14±0.05% and the previously reported value of 6.7±0.6% were larger by about 10%. The data for ^<105>Ru were in agreement with the evaluated values within the uncertainties, but uncertainties were greatly improved from 3% to 0.6% for intense γ-ray. On the other hand, those of 306.1 keV and 318.9 keV for ^<105>Rh were 4.76±0.05% and 16.99±0.17% and the evaluated values of 5.1±0.6% and 19.1±0.6% were larger by about 10%.