The monitoring of radioxenon in the atmosphere is one of several methods to detect nuclear weapon tests as part of the Comprehensive Nuclear Test Ban Treaty. For ultra-low radioxenon detection, a phoswich detector with two scintillators coupled to a single photomultiplier was explored to simplify the time-based coincidence detection systems such as SAUNA and ARSA. We present a well-type NaI(Tl)/BC404 phoswich detector, newly developed by the Institute of Nuclear Physics and Chemistry, which consist of a thin BC404 cell to detect beta and conversion electrons, and a NaI(Tl) crystal to detect X-rays and gamma-rays. Moreover, the pulses of the detector were sampled and processed at 1GS/s with 10-bit ADC by a high-speed digitizer. In the preliminary experiments with various sources, the detector was test to have comparable sensitivity with the existing detectors in energy resolution, detection efficiency, background, memory effect and MDCs. The gamma resolution achieved 6.9% at 662keV. The coincidence efficiency of ¹³³Xe at 81keV region is about 71% while gas loss in the stainless tube and the valve was accounted. In addition, the MDC of ¹³³Xe was calculated by 0.2mBq/m³ under current gas process capability.

大气中放射性氙的监测是作为《全面禁止核试验条约》一部分的检测核武器试验的几种方法之一。对于超低放射性氙检测，探索了一种将两个闪烁体耦合到一个光电倍增管的荧光检测器，以简化基于时间的巧合检测系统，例如SAUNA和ARSA。我们介绍一种由核物理和化学研究所新开发的井型NaI（Tl）/ BC404荧光检测器，该检测器由可检测β和转换电子的薄BC404细胞和可检测X的NaI（Tl）晶体组成射线和伽马射线。此外，通过高速数字化仪对检测器的脉冲进行采样，并使用10位ADC以1GS / s的速度对其进行处理。在各种来源的初步实验中，经过测试，该探测器在能量分辨率，探测效率，背景，记忆效应和MDC方面具有与现有探测器相当的灵敏度。在662keV时，伽马分辨率达到6.9％。的重合效率在81keV区域的¹³³ Xe约为71％，而不锈钢管和阀门中的气体损失则被考虑在内。另外，在当前的气体处理能力下，以0.2mBq / m ³计算出¹³³ Xe的MDC 。