【摘要】 中子在探测器中能产生与暗物质粒子(WIMPs)类似的核反冲信号,对于低背景的暗物质直接探测实验,精确测量和排除中子的干扰尤其重要。为测量中国锦屏地下实验室(CJPL)中子本底的通量,研制了高效的、具有很强"中子-伽马"分辨的掺钆液闪快中子探测器。介绍了掺钆液闪中子探测器的研制和性能,包括探测器形状和尺寸的设计,液体闪烁体类型、光电倍增管型号以及液闪容器材料的选择,探测器的伽马能量刻度以及中子与伽马信号的甄别。用Am-Be中子源对探测器进行探测效率刻度,得到阈值为0.2 MeV等效电子能量的中子探测效率为(6.30±0.30)%,满足中国锦屏地下实验室对中子通量测量的要求。更多还原

【Abstract】 Astronomical observation and theoretical motivations have strongly indicated that most of matter in the Universe is made of cold dark matter.A well-motivated class of dark matter candidate is Weakly Interacting Massive Particles(WIMPs).Neutron and WIMPs can produce nuclear recoils via elastic scattering off ordinary matter in terrestrial detectors to the point where neutron can bring a false positive reading.Of crucial importance to the direct detections of dark matter searches is to identify the neutron background and its influence.In order to measure the flux and spectrum of neutron background in China JinPing Underground Laboratory(CJPL),an efficient Gd-doped liquid scintillator detector which possesses a strong(n-γ)discrimination was developed.This paper reports the design and performance of the detector geometry,the type of liquid scintillators and photomultiplier tubes(PMT)as well as the low radioactivity surrounding materials and the energy calibration and the capability of neutron and gamma discrimination.Am-Be neutron source was used to evaluate the neutron detection efficiency and the result is(6.30±0.30)% above 0.2 MeV equivalent electron energy.更多还原