A new application of the Sohrabi albedo neutron dosimeters is reported for the first time for determination of very low-level neutron ambient dose equivalents on and around a 3.5 kJ plasma focus device (PFD). The Sohrabi dosimeters basically use a polycarbonate track detector as bare and/or in contact with B convertor(s) under special cadmium cover arrangements. Its sensitivity was improved by using enriched B under new cadmium arrangements in order to detect epithermal neutrons in addition to fast and thermal neutrons. Results of 12 dosimeters installed externally around the PFD at different azimuthal (φ) and polar (θ) angles showed that azimuthal (φ) fast, epithermal, thermal, and total neutron ambient dose equivalents were symmetric and isotropic, respectively, with values 55.15 ± 8.36, 1.36 ± 02, 0.53 ± 03, and 57.04 ± 8.62 μSv/shot at ~25 cm from anode top. Polar (θ) neutron ambient dose equivalent values on z-axis relative to 90 angle were relatively higher. Results of 38 dosimeters placed on PFD facility walls for workplace monitoring and on a BOMAB phantom at operator's location for personal dose equivalent determination showed values below minimum detection limits after exposure to 130 PFD shots. However, an operator's personal dose equivalents at ~1.0 and ~3.0 m from the anode top were estimated to be, respectively, ~13.7 and ~1.52 mSv y using azimuthal angle (φ) values if the PFD operates, for example, up to 20 shots per day for 200 d y. Even under such an extreme assumption, annual personal dose equivalent is still much below 20 mSv, the annual ICRP dose limit for workers.

中文翻译：

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索拉比反照率中子剂量计在等离子体聚焦装置周围的新应用。

首次报道了 Sohrabi 反照率中子剂量计的新应用，用于确定 3.5 kJ 等离子体聚焦装置 (PFD) 及其周围的极低水平中子环境剂量当量。Sohrabi 剂量计基本上使用聚碳酸酯径迹探测器作为裸露和/或在特殊镉盖布置下与 B 转换器接触。通过在新的镉排列下使用富集硼，除了快中子和热中子之外，还可以检测超热中子，从而提高了其灵敏度。PFD 周围安装的 12 个不同方位角 (φ) 和极 (θ) 角剂量计的结果表明，方位角 (φ) 快剂量当量、超热剂量当量、热剂量当量和总中子环境剂量当量分别是对称的和各向同性的，其值为 55.15 ± 8.36、1.36 ± 02、0.53 ± 03 和 57.04 ± 8.62 μSv/发射，距阳极顶部约 25 cm。z 轴相对于 90 度角的极性 (θ) 中子环境剂量当量值相对较高。放置在 PFD 设施墙壁上用于工作场所监测的 38 个剂量计和放置在操作员位置的 BOMAB 模型上用于确定个人剂量当量的 38 个剂量计的结果显示，在暴露于 130 次 PFD 射击后，剂量计的值低于最低检测限。然而，如果 PFD 运行时，例如，操作员在距阳极顶部约 1.0 和约 3.0 m 处的个人剂量当量使用方位角 (φ) 值估计分别为约 13.7 和约 1.52 mSv y，例如高达 20每天注射 200 天。即使在如此极端的假设下，年度个人剂量当量仍远低于 20 毫希沃（ICRP 工作人员年度剂量限值）。