Study of Ultra-high Energy Cosmic Rays at Tibetan Highlands

青藏高原超高能宇宙线研究

基本信息

批准号：
01044039
负责人：
YUDA Toshinori
金额：
$ 3.84万
依托单位：
Institute for Cosmic Ray Research, University of Tokyo
依托单位国家：
日本
项目类别：
Grant-in-Aid for international Scientific Research
财政年份：
1989
资助国家：
日本
起止时间：
1989 至 1990
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-01044039/
关键词：
Air shower array Yangbajing Gamma ray point source Fast timing Scintillation counter TKO Cyg. X-3

项目摘要

A new air shower experiment, aiming to search for celestial gamma ray point sources, has been started from 1989 with Chinese scientists at Yangbajing (4,300m a. s. l., 90.5^ﾟE and 30.1^ﾟN) in Tibet. The present array consists of 49 scintillation counters for fast timing (FT), each of which has an area of 0.5 m^2 and is placed in a grid pattern with a spacing of 15 m. Other 16 density counters surround the FT counter array to select the showers whose core fall inside the array. The TKO and CAMAC system, controlled by a 32 bit micro-computer, is employed in this experiment. The data are recorded on a 8 mm video tape of about 2 GB capacity. A Rb clock with a stability of <54 mus/month is equipped to receive the arrival time of air showers precisely. The operation, atarted fully from June of 1990, is now successively continued with a high trigger rate of about 20 Hz to search for gammaray point sources in the energy region lower than 100 TeV. For the time being, only our array can detect s … More uch rather low energy gamma-rays effectively, since the observation site is located at high altitude.The performance of the present array was examined by using the experimental data, comparing those with a Monte Carlo simulation. This shows that the arrival direction of air showers can be determined with an angular resolution of about 0.5^ﾟ at 100 TeV. Also the energy resolution is estimated to be about 30% for a 100 TeV gamma ray. The detectable shower energy is estimated to be about 20 TeV, and the non-bias energy corresponds to about 40 TeV for gamma ray showers. Our experiment is therefore considered to have a distinctive feature among a lot of air shower arrays working now in the world, giving a capability of observing gamma ray point sources in the several 10 TeV energy region where both of mirror and array experiment on the ground are inaccessible.We still need to operate this array at least for more than one year to examine whether Cyg. X-3 and other point source candidates really emit high energy gamma rays steadily or not. The first result will be given in this fall. Less

1989年，中国科学家在西藏羊八井（纬度4300米，东经90.5^ﾟ，北纬30.1^ﾟ）开始了一项新的空气簇射实验，旨在寻找天体伽马射线点源。目前的阵列由49个组成。用于快速计时（FT）的闪烁计数器，每个闪烁计数器的面积为0.5 m^2并放置其它16个密度计数器以15 m的间隔排列在FT计数器阵列周围，以选择其核心落在阵列内的流星，由32位微计算机控制。实验数据记录在约2GB容量的8毫米录像带上，配备稳定度<54μs/月的Rb时钟，以精确接收风淋室的到达时间。从1990年6月开始，现在陆续继续以大约20 Hz的高触发频率来搜索低于100 TeV能量区域的伽马射线点源，目前只有我们的阵列可以探测到这样相当低的能量。由于观测地点位于高空，因此可以有效地检测能量伽马射线。利用实验数据检验了本阵列的性能，并与蒙特卡罗模拟进行了比较，结果表明，空气阵雨的到达方向可以。在 100 TeV 处，角分辨率约为 0.5^ﾟ。此外，对于 100 TeV 伽马射线，能量分辨率估计约为 30%，可检测的簇射能量估计约为 20 TeV，并且无偏差。因此，我们的实验被认为是目前世界上许多正在运行的空气簇射阵列中具有显着特征的能量，相当于伽马射线簇射的约 40 TeV。观测伽马射线点源的能力在几个10TeV的能量区域，地面镜面和阵列实验都无法实现。我们仍然需要运行这个阵列至少一年以上来检验Cyg是否是其他点源候选者。是否能够稳定地发射高能伽马射线，第一个结果将在今年秋天给出。