A single stage vacuum-type proton recoil neutron telescope (PRT) was used for accurate measurement of 14.57 MeV neutron fluence rate from an indigenously developed D-T neutron generator at Purnima, BARC. The telescope consists of a polyethylene radiator having 4 cm diameter and CsI (Tl) scintillation crystal having thickness 1.5 mm and 4 cm diameter separated by 20.5 cm kept in a vacuum chamber. The neutron detection efficiency of the telescope for 14.57 MeV neutrons was calculated analytically using n-p scattering cross section data from Evaluated Nuclear Data File VII and also evaluated using fluka simulation. The relativistic transformation of n-p differential scattering cross section from centre-of-mass to laboratory system was used for calculating the efficiency of PRT. The 14.57 MeV neutron fluence rate was also measured using copper foils. The comparison of fluence rate measured using PRT and copper foil activation techniques is presented in this paper. The total uncertainty in measurement using PRT and copper foil activation technique is found to be 3.93 and 6.97%, respectively.

中文翻译：

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使用质子反冲中子望远镜绝对测量14.57 mev中子通量率。

单级真空型质子反冲中子望远镜（PRT）用于精确测量来自BARC Purnima的本地开发的DT中子发生器的14.57 MeV中子注量率。望远镜由直径为4厘米的聚乙烯辐射体和厚度为1.5毫米，直径为4厘米，间隔20.5厘米的CsI（Tl）闪烁晶体组成，并保存在真空室内。使用来自“评估核数据文件” VII的np散射截面数据，通过解析计算得出了望远镜对14.57 MeV中子的探测效率，并使用fluka模拟对其进行了评估。np差分散射截面从质心到实验室系统的相对论转换用于计算PRT的效率。还使用铜箔测量了14.57 MeV中子注量率。本文介绍了使用PRT和铜箔活化技术测得的注量率的比较。使用PRT和铜箔活化技术进行测量的总不确定度分别为3.93和6.97％。