Verification of He-3 proportional counters’ fast neutron sensitivity through a comparison with He-4 detectors
Verification of He-3 proportional counters’ fast neutron sensitivity through a comparison with He-4 detectors
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通过与He-4探测器的比较验证He-3正比计数器的快中子灵敏度
DOI：
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发表时间：
2020
期刊：
影响因子：
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通讯作者：
R. Hall
中科院分区：
文献类型：
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作者：
F. Piscitelli;G. Mauri;A. Laloni;R. Hall
在中子散射科学领域，许多仪器都需要热中子和冷中子探测器。多年来，氦-3一直是热中子和冷中子探测的主要参与者之一。如今，世界各地的中子设施都在推动他们的技术来增加仪器提供的可用通量；这使得一种全新的科学格局成为可能。与不断增加的可用通量相辅相成的是，更好的信号与背景比(S/B)使执行新型测量成为可能。例如，在中子反射计中，动力学研究的时间分辨率受到可用的S/B的限制。改进的S/B为亚秒动力学研究打开了可能性。为此，这篇手稿重新审视了如今的“黄金标准”中子探测的本底灵敏度。快中子和伽马射线是中子散射实验中的主要本底物质。本文通过与氦-4计数器的比较，研究了氦-3探测器对快中子、宇宙射线和伽马射线的探测效率(灵敏度)。与氦-4的比较允许将热(和冷)中子从基于氦-3的计数器中的快中子贡献中分离出来，否则这些快中子贡献是纠缠的，验证了以前间接方法的结果。发现了相对较高的灵敏度。此外，本文还给出了ESS地面处宇宙中子注量的估算，这也是背景的来源之一。
In the field of neutron scattering science, a large variety of instruments require detectors for thermal and cold neutrons. Helium-3 has been one of the main actors in thermal and cold neutron detection for many years. Nowadays, neutron facilities around the world are pushing their technologies to increase the available flux delivered at the instruments; this enables a completely new science landscape. Complementary with the increasing available flux, a better signal-to-background (S/B) ratio enables to perform new types of measurements. For instance, in neutron reflectometry, the time resolution for kinetic studies is limited by the available S/B. An improved S/B opens the possibility of sub-second kinetic studies. To this aim, this manuscript re-examines the background sensitivity of today’s “gold standard” neutron detection. Fast neutrons and gamma rays are the main background species in neutron scattering experiments. The efficiency (sensitivity) of detecting fast neutrons, cosmic rays and gamma rays, for a Helium-3-based detector is studied here through the comparison with Helium-4 counters. The comparison with Helium-4 allows to separate the thermal (and cold) neutron from the fast neutron contributions in Helium-3-based counters which are otherwise entangled, verifying previous results from an indirect method. A relatively high sensitivity is found. Moreover, an estimate for the cosmic neutron fluence, also a source of background, at ground level at ESS is presented in this manuscript.