Subjects: Physics >> Nuclear Physics submitted time 2024-02-20
Abstract: The angle-differential cross sections of neutron-induced d production from carbon were measured at neutron energies 33.9 MeV at China Spallation Neutron Source (CSNS) Back-n white neutron source. By employing the ΔE-E telescopes of the Light-charged Particle Detector Array (LPDA) system at 24.5° to 155.5° in the laboratory system, the angle-differential cross sections of the 12C(n,d)x reactions were measured.
The experimental results are in good agreement with the previous ones.The present work can provide a reference to the data library considering the lack of experimental data.
Subjects: Astronomy >> Astrophysical processes submitted time 2023-12-06 Cooperative journals: 《天文研究与技术》
Abstract: The Large High Altitude Air Shower Observatory (LHAASO) is located in Haizi Mountain, Daocheng County, Sichuan Province, with an average altitude of 4410 meters. It belongs to a typical alpine climate with rapid weather changes. The Wide Field of view Cherenkov Telescope Array (WFCTA), as one of the three major observation arrays of LHAASO, requires operation in the clear nights. To ensure the normal operation of the telescope, it is necessary to constantly detect rain and snow conditions, so that WFCTA can be closed promptly in case of rain and snow weather. However, due to the low temperature, traditional rain and snow sensors cannot work properly at the LHAASO site. Therefore, the heating device was induced to make the rain and snow sensors fit the weather in Daocheng. After designing and testing in the laboratory, the on-site experiment was also carried out at the LHAASO site. The results show that the high-sensitivity rain and snow sensor can maintain the temperature above ice point at the surface of the sensor in horrible weather, and can effectively monitor rain and snow in real-time at the LHAASO site, which can provide strong support for the normal operation of the Wide Field of view Cherenkov Telescope Array.
Subjects: Astronomy >> Astrophysical processes submitted time 2023-12-04 Cooperative journals: 《天文研究与技术》
Abstract: The Large High Altitude Air Shower Observatory (LHAASO) is situated in Haizi Mountain, Daocheng County, Sichuan Province, at an average altitude of 4 410 meters. The laser calibration system is a vital component of the Wide-Field-of-view Cherenkov Telescope Array (WFCTA) in LHAASO, utilized to calibrate the absolute gain of WFCTA for the received photons. The energy measurement system in the laser calibration system comprises an energy sensor, an energy meter, and a temperature control system, primarily employed to precisely measure the energy of the pulsed laser beam emitted into the WFCTA field of view. This paper primarily focuses on the relative calibration and performance of the energy sensor, and proposes a temperature control system to ensure the energy sensor′s normal operation in the harsh plateau environment. The accuracy of energy measurement about laser pulse can be improved by relative calibration. The performance test results of the energy sensor demonstrate that the non-uniformity is less than 1.5% within the circular area with a diameter of 8 mm centered on the energy sensor. The incident angle of the laser beam has negligible impact on the measurement of the laser pulse energy by the energy sensor, but the reflection of the laser by the energy sensor can damage the laser when the laser beam is vertically incident. Hence, avoiding the vertical incidence of the laser beam on the energy sensor is crucial. Furthermore, the energy sensor exhibits a strong temperature effect. Therefore, an independent temperature control system is developed in this paper to ensure the energy sensor′s normal operation, fulfilling the experiment′s requirements. These research works serve as the foundation for the laser calibration system′s regular operation and functioning.
Subjects: Astronomy >> Astrophysical processes submitted time 2021-09-29 Cooperative journals: 《天文研究与技术》
Abstract:三维升降转台是高海拔宇宙线观测站(LHAASO)广角切伦科夫望远镜阵列(WFCFA)成像激光雷达标定系统的核心组成部分,主要由慢控子系统、机械子系统和标准零点子系统构成,用于精确控制激光束的出射方向。本文采用高精度数字图像处理技术对三维升降转台的性能进行研究,结果表明其旋转和升降定位精度分别为0.005°和0.056 mm、重复精度分别为0.003°和0.075 mm,满足成像激光雷达标定系统的实验要求。三维升降转台的自动控制巡航功能,有效减少了人工干预,提高了系统远程使用的可靠性和效率。标准零点的校准功能可以有效地监测三维升降转台的定位精度并且在失准的情况下,能够实现远程校准,以确保三维升降转台长期高精度稳定运行。
Subjects: Astronomy >> Astrophysical processes submitted time 2021-05-27 Cooperative journals: 《天文研究与技术》
Abstract:GECAM是专门针对引力波伽马暴的研究机遇而提出的中国科学院空间科学(二期)先导专项卫星任务。GECAM卫星通过数传、遥测以及北斗短报文三个通道下行触发、事例、并道、工程以及短报文等多种类型的数据,数据预处理过程需要对这些数据进行快速正确处理,以满足科学家对天文事件数据正确性和时效性的要求。本文针对GECAM卫星数据处理时效性要求高、数据连续完整、多信道数据融合处理以及触发事件数据切分等特点,对科学数据处理流程和天文警报信息处理流程进行了设计,概述了关键核心算法的思路与实现方法。卫星发射入轨后,数据预处理软件运行良好,正确性和及时性指标满足要求,为后续爱因斯坦探针(EP)卫星、中法天文卫星(SVOM)等空间天文卫星开展数据预处理工作提供了参考。
Subjects: Astronomy >> Astrophysical processes submitted time 2019-12-02 Cooperative journals: 《天文研究与技术》
Abstract: 地面水切伦科夫探测器实验(WCDA)是高海拔宇宙线观测站(LHAASO)项目的重要组成部分,主要物理目标是实现在甚高能中低能段(100 GeV~30 TeV)对整个北天区伽马源的巡天观测。为了确保对辐射源探测的指向准确性,需要对探测器阵列进行时间标定。本文主要介绍了WCDA探测器中时间标定方法、标定系统的搭建以及关键部件-分光光纤束的批量测试。
Subjects: Astronomy >> Astrophysical processes submitted time 2019-11-27 Cooperative journals: 《天文研究与技术》
Abstract: 水切伦科夫探测器阵列(WCDA)是高海拔宇宙线观测站(LHAASO)的主体探测之一,水作为探测器的唯一探测介质,水的洁净度将直接影响探测器对切伦科夫光的探测效率。为保证WCDA物理目标的实现,水衰减长度的实时测量和监测至关重要,是探测器正常运行和标定的关键工作之一。本实验分别介绍了水衰减长度测量装置和紫外可见分光光度计的工作原理,并通过不同波长的LED对各种样品水进行测量,将两种方法的数据结果进行对比分析,找出了两种装置的测量误差分别为0.22m和0.18m,以及工业指标吸光度与科研指标水衰减长度之间的对应关系,并为GEANT4模拟确定了一种Querry水质模型,进一步推进了模拟的真实化。通过对WCDA一号水池水衰减测量装置的验证及从注水到稳定运行期间的水质监测的数据研究,总结了一套稳定可靠的水质监测方案,为二、三号水池的监测工作奠定了良好的基础。
Subjects: Astronomy >> Astrophysical processes submitted time 2019-11-13 Cooperative journals: 《天文研究与技术》
Abstract: 高海拔宇宙线观测站(LHAASO)的核心科学目标是探索高能宇宙线起源以及相关的宇宙演化、高能天体运动和新物理前沿的研究。通过大面积铺设μ子探测器(MD)极大的压低宇宙射线背景,从而提高高能伽马射线探测的灵敏度。作为MD的核心部件之一的光电倍增管(PMT)负责接收水中的切伦科夫光子并将其转换成电信号输出,因此PMT的性能好坏直接影响MD的性能。稻城实验室2%抽样测试结果表明PMT的各性能达到MD的指标要求,与批量测试结果的相对偏差小于2%。