arXiv subjects

Xun-Zhen Yu

Publications and source records attributed to Xun-Zhen Yu.

5 recordsLinked to original sources

arXiv2016

Discrimination of neutrons and γ-rays in liquid scintillator based on Elman neural network

In this work, a new neutron and γ(n/γ) discrimination method based on an Elman Neural Network (ENN) is proposed to improve the discrimination performance of liquid scintillator (LS) detectors. Neutron and γ data were acquired from an EJ-335 LS detector, which was exposed in a 241Am-9Be radiation field. Neutron and γ events were discriminated using two methods of artificial neural network including the ENN and a typical Back Propagation Neural Network (BPNN) as a control. The results show that the two methods have different n/γ discrimination performances. Compared to the BPNN, the ENN provides an improved of Figure of Merit (FOM) in n/γ discrimination. The FOM increases from 0.907 {\pm} 0.034 to 0.953 {\pm} 0.037 by using the new method of the ENN. The proposed n/γ discrimination method based on ENN provides a new choice of pulse shape discrimination in neutron detection.

physics.ins-det↗

arXiv2016

Measurement of photoelectron yield of the prototype for the CDEX-10 liquid argon detector

The China Dark Matter Experiment (CDEX) is a low background experiment at China Jinping Underground Laboratory (CJPL) designed to directly detect dark matter with a high-purity Germanium (HPGe) detector. In the second phase CDEX-10 with a 10 kg Germanium array detector system, the liquid argon (LAr) anti-compton active shielding and cooling system is proposed. For purpose of studying the properties of LAr detector, a prototype with an active volume of 7 liters of liquid argon was built and operated. The photoelectron yields, as a critically important parameter for the prototype detector, have been measured to be 0.051-0.079 p.e./keV for 662 keV Gamma lines at different positions. The good agreement between the experimental and simulation results has provided a quite reasonable understanding and determination of the important parameters such as the Surviving Fraction of the Ar2 excimers, the absorption length for 128 nm photons in liquid argon, the reflectivity of Teflon and so on.

physics.ins-det↗

arXiv2014

Study of the material photon and electron background and the liquid argon detector veto efficiency of the CDEX-10 experiment

The China Dark Matter Experiment (CDEX) is located at the China Jinping underground laboratory (CJPL) and aims to directly detect the WIMP flux with high sensitivity in the low mass region. Here we present a study of the predicted photon and electron backgrounds including the background contribution of the structure materials of the germanium detector, the passive shielding materials, and the intrinsic radioactivity of the liquid argon that serves as an anti-Compton active shielding detector. A detailed geometry is modeled and the background contribution has been simulated based on the measured radioactivities of all possible components within the GEANT4 program. Then the photon and electron background level in the energy region of interest (<10^-2 events kg-1 day-1 keV-1 (cpkkd)) is predicted based on Monte Carlo simulations. The simulated result is consistent with the design goal of CDEX-10 experiment, 0.1 cpkkd, which shows that the active and passive shield design of CDEX-10 is effective and feasible.

physics.ins-det↗

arXiv2013

Characterization of large area photomultiplier ETL 9357FLB for liquid argon detector

The China Dark Matter Experiment (CDEX) Collaboration will carry out a direct search for weakly interacting massive particles with germanium detectors. Liquid argon will be utilized as an anti-Compton and cooling material for the germanium detectors. A low-background and large-area photomultiplier tube (PMT) immersed in liquid argon will be used to read out the light signal from the argon. In this paper we carry out a careful evaluation on the performance of the PMT operating at both room and cryogenic temperatures. Based on the single photoelectron response model, the absolute gain and resolution of the PMT were measured. This has laid a foundation for PMT selection, calibration and signal analysis in the forthcoming CDEX experiments.

physics.ins-det↗

arXiv2013

The CDEX-1 1 kg Point-Contact Germanium Detector for Low Mass Dark Matter Searches

The CDEX Collaboration has been established for direct detection of light dark matter particles, using ultra-low energy threshold p-type point-contact germanium detectors, in China JinPing underground Laboratory (CJPL). The first 1 kg point-contact germanium detector with a sub-keV energy threshold has been tested in a passive shielding system located in CJPL. The outputs from both the point-contact p+ electrode and the outside n+ electrode make it possible to scan the lower energy range of less than 1 keV and at the same time to detect the higher energy range up to 3 MeV. The outputs from both p+ and n+ electrode may also provide a more powerful method for signal discrimination for dark matter experiment. Some key parameters, including energy resolution, dead time, decay times of internal X-rays, and system stability, have been tested and measured. The results show that the 1 kg point-contact germanium detector, together with its shielding system and electronics, can run smoothly with good performances. This detector system will be deployed for dark matter search experiments.

physics.ins-det↗