Neutron spectrum change with thermal moderator temperature in a compact electron accelerator-driven neutron source and its effects on spectroscopic neutron transmission imaging
Neutron spectrum change with thermal moderator temperature in a compact electron accelerator-driven neutron source and its effects on spectroscopic neutron transmission imaging
复制标题
DOI：
10.1080/00223131.2018.1561339
复制
发表时间：
2019-02-01
影响因子：
1.2
通讯作者：
Kamiyama, Takashi
中科院分区：
文献类型：
--
作者：
Ishikawa, Hirotaku;Kai, Tetsuya;Kamiyama, Takashi
近年来，紧凑型加速器驱动中子源（CANS）引起了人们的关注。在CANS中，从成本、简单性和可维护性的角度考虑，通常使用简单的热中子慢化剂，例如聚乙烯。在大多数情况下，这种慢化剂的温度没有得到控制，虽然这是自然的，慢化剂温度和中子谱将随着加速器的操作而改变。因此，我们同时测量中子谱和温度的聚乙烯慢化剂在北海道大学中子源（HUNS）驱动的紧凑型电子加速器，以观察任何温度变化的影响，光谱透射测量的可靠性。在HUNS情况下，中子有效温度与慢化剂温度之比是恒定的，但在加速器开始运行后的一小时内，两者都增加了4-5 K。这表明，中子有效温度是很好的估计慢化剂温度。通过在慢化剂预热之前排除数据收集，可以很容易地避免温度变化的影响。这些结果表明，在紧凑型电子加速器驱动的中子源与热中子慢化剂，以保证光谱透射测量的可靠性，而不牺牲成本，简单性和可维护性的监测慢化剂温度是推荐的。
Recently, Compact Accelerator-driven Neutron Sources (CANSs) are attracting attention. In CANSs, a simple thermal neutron moderator such as polyethylene is often used from the viewpoints of cost, simplicity and maintainability. In most cases, the temperature of such a moderator has not been controlled although it is natural that the moderator temperature and the neutron spectrum will change with accelerator-operation. Thus, we simultaneously measured neutron spectra and the temperature of a polyethylene moderator at the Hokkaido University Neutron Source (HUNS) driven by a compact electron accelerator to observe the effect of any temperature change on the reliability of spectroscopic transmission measurement. The ratio of the neutron effective temperature and the moderator temperature was constant in HUNS case, although both increased by 4-5 K within one hour after the start of accelerator-operation. This indicated that the neutron effective temperature was well estimated by the moderator temperature. The effect of the temperature change can be easily avoided by excluding data collection before the moderator warms up. These results suggested that the monitoring of moderator temperature is recommended in compact electron accelerator-driven neutron sources with a thermal neutron moderator to guarantee reliability of spectroscopic transmission measurement without sacrifices of cost, simplicity and maintainability.