Abstract A neutron irradiation facility based on four 241Am–Be sources, each one with an activity of 111 GBq, placed in Plexiglas pipes inside a tank filled with water used both as a moderator and a biological shielding, has been realized at the Engineering Department of Palermo University. In view of its use as a testing tool in various research activities, a characterisation of the irradiator has been carried out through the determination of neutron and gamma-ray flux profiles, the evaluation of the thermal to total neutron flux percentage ratio and of the epithermal neutron shaping factor. To this aim, results of a Monte Carlo (MCNP5 code) simulation based on a previously validated source model have been compared with the experimental results obtained from TLD dosimeters and activated gold foils. Experimental values show a good agreement with MCNP5 evaluations, highlighting a gradually decreasing of dose values as a function of the distance from the lying plane of sources. Maximum values of experimental neutron fluxes have been found to be (3.73 ± 0.38) × 104 cm−2 s−1 (thermal) and (2.13 ± 0.25) × 104 cm−2 s−1 (epithermal and fast), with a percentage of 64% of thermal to total neutron flux and epithermal neutron shaping factor equal to −0.16 ± 0.04. Both neutron and gamma fluxes for the most used positions inside the irradiation channel can then be provided and the main parameters for any irradiation plane can be easily established.

中文翻译：

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鉴于其用作研究测试工具，241Am–Be 辐照器中的中子和伽马射线辐射场表征

摘要 一个基于四个 241Am-Be 源的中子辐照设施，每个源的活度为 111 GBq，放置在一个装满水的水箱内的有机玻璃管中，用作慢化剂和生物屏蔽，已在工程部实现。巴勒莫大学。鉴于其在各种研究活动中作为测试工具的用途，已通过确定中子和伽马射线通量分布、评估热与总中子通量百分比和超热辐射的评估，对辐照器进行了表征。中子整形因子。为此，基于先前验证的源模型的蒙特卡罗（MCNP5 代码）模拟结果与从 TLD 剂量计和活化金箔获得的实验结果进行了比较。实验值显示出与 MCNP5 评估的良好一致性，突出显示剂量值随着与源所在平面的距离而逐渐减小。已发现实验中子通量的最大值为 (3.73 ± 0.38) × 104 cm−2 s−1（热）和 (2.13 ± 0.25) × 104 cm−2 s−1（超热和快），并带有百分比64% 的热中子通量和超热中子成形因子等于 -0.16 ± 0.04。然后可以提供辐照通道内最常用位置的中子和伽马通量，并且可以轻松建立任何辐照平面的主要参数。38) × 104 cm−2 s−1（热）和 (2.13 ± 0.25) × 104 cm−2 s−1（超热和快），占总中子通量和超热中子成形因子的 64%等于 -0.16 ± 0.04。然后可以提供辐照通道内最常用位置的中子和伽马通量，并且可以轻松建立任何辐照平面的主要参数。38) × 104 cm−2 s−1（热）和 (2.13 ± 0.25) × 104 cm−2 s−1（超热和快），占总中子通量和超热中子成形因子的 64%等于 -0.16 ± 0.04。然后可以提供辐照通道内最常用位置的中子和伽马通量，并且可以轻松建立任何辐照平面的主要参数。