Online charge calibration of LHAASO-WCDA-a study with the engineering array

LHAASO-WCDA is a large ground-based water Cherenkov detector array planned to be built at Shangri-La, Yunnan Province, China. As a major component of the LHAASO project, the main purpose of LHAASO-WCDA is to survey the northern sky for very-high-energy (above 100 GeV) gamma ray sources and measure the spectrum. To gain full knowledge of the water Cherenkov technique and to investigate the engineering issues, a 9-cell detector array has been built at the Yang-Ba-Jing site, neighboring the ARGO-YBJ experiment. With the array, charge calibration methods for both low and high ranges of the PMT readout are studied, whose result shows that a precision at several percentages can be reached, which can satisfy the requirement of the detector array. During the long term operation, the charge calibration stability and environmental affection are studied; in this paper, the results are discussed. These calibration methods are proposed to be applied in the future LHAASO-WCDA project.     

Online charge calibration of LHAASO-WCDA——a study with the engineering array

LHAASO-WCDA is a large ground-based water Cherenkov detector array planned to be built at ShangriLa, Yunnan Province, China. As a major component of the LHAASO project, the main purpose of LHAASO-WCDA is to survey the northern sky for very-high-energy（above 100 GeV） gamma ray sources and measure the spectrum. To gain full knowledge of the water Cherenkov technique and to investigate the engineering issues, a 9-cell detector array has been built at the Yang-Ba-Jing site, neighboring the ARGO-YBJ experiment. With the array, charge calibration methods for both low and high ranges of the PMT readout are studied, whose result shows that a precision at several percentages can be reached, which can satisfy the requirement of the detector array. During the long term operation, the charge calibration stability and environmental afection are studied; in this paper, the results are discussed. These calibration methods are proposed to be applied in the future LHAASO-WCDA project.     

空间低能离子探测器的紫外响应测试

在空间离子探测过程中,太阳紫外光也会进入探测器产生光污染信号。为了考察它对离子探测的影响,搭建了一套模拟太阳紫外光污染的地面测试系统,并对自主研制的空间低能离子探测器原理样机进行了紫外响应测试。实验结果表明:沿水平方向进入分析器的紫外光响应可以忽略,而以一定倾斜角进入分析器的紫外光响应计数率约为102~ 103 s−1。根据测试结果,估算出探测器对太阳紫外光的抑制率约为10−8,分析了紫外光污染对探测空间低能离子如质子和 粒子的影响。对于质子,由于其通量大,紫外光的影响不大。而对于通量较小的 粒子,紫外光的影响较大,需要进一步采取有效措施进行抑制。此外,本测试系统可以推广到其它空间粒子探测器的太阳紫外光污染的地面模拟测试。In the detection of space ions, solar ultraviolet (UV) can also enter the detector and generate a noise to the signal of ions. A testing system on the ground is built to test the UV response of detector. Experiments on a home-made principle prototype of space low-energy ion detector are carried out by using this system. The results show that the response of detector to the UV entering the electrostatic analyzer along the horizontal direction can be negligible and counts of the response to the UV along a bias direction are about 102 ~103 s−1. According to the measured results, the UV suppression ratio is estimated to be about 10−8 and the inuence of solar UV on the detection of space low-energy ions such as proton and alpha particle has been analyzed. For proton, the inuence is insigni cant due to its high ux. But for the low ux alpha particle, the inuence of solar UV is noticeable and further rejection is needed. In addition, this system can also be applied to test the UV response of other space particle detectors.