Study of ultra-high energy cosmic rays at Tibetan highlands.

中国物理学家在西藏的羊八井（海拔4300m）建造了一个新的空气淋浴阵列，用于搜索来自天王星等天体点源的超高能量伽马射线。X-3-3。主要目的是研究高能宇宙射线的起源和加速机理。该阵列由65ch闪烁探测器组成，其中49个0.5mX^2面积的探测器以15m的间距布置在网格中，以可行的精度测量每个风淋的到达时间和粒子密度。该系统由TKO和CAMAC组成，由微机控制。数据记录在一个2.3 gb的8mm录像带中。利用GPS和Rb时钟实现了约10秒/天的时间分辨率。目前风淋室的触发频率约为20hz。通过与Monte Carlo模拟的比较，表明观测到的阵雨平均能量约为20 TeV，能量在10 TeV左右或小于10 TeV的阵雨可以被探测到，且没有严重的偏差。角分辨率约为1度。只有我们的阵列才能以可行的精度探测到这种低能量的阵雨，主要是因为观测水平高。由于严重的探测偏差，在密封层附近工作的空气切伦科夫探测器和空气淋室阵列都无法观测到这些伽马射线。高能宇宙射线的月球阴影被我们的阵列很好地观测到，其亏空约为4.2西格玛。从实验结果可以直接估计出角分辨率约为1度。搜寻来自天鹅座的高能伽马射线。3、她。X-1和蟹状星云/脉冲星，包括一颗神经元星并发射强大的x射线，已经仔细地做了否定的结果。它们的通量上限（95%CL）估计为2.03 × 10^<-12>/cm^2。秒,0.59 x10 ^ ^ < -12 > /厘米2。SEC和1.48 × 10^<-12>/cm^2/cm^2。分别交会。用惠普尔切伦科夫反射镜在TeV区域观测到了蟹状星云的伽马射线。这一结果可在10 TeV能量区域进行实验验证，再运行一年。我们需要提前将有效面积的平面扩大3 × 10^4m^2

A new air shower array has been constructed at Yangbajing (4300m above sea level) in Tibet with Chinese physicists to search for ultra-high energy gamma-rays from celestial point sources such as Cyg. X-3-3. The main aim is to study the origin and acceleration mechanism of high energy cosmic rays.The array consists of 65ch scintllation detectors, among which 49 detectors of 0.5mX^2 area eacti are arranged in a grid pattern of a spacing 15m to measure the arrival time and particle density of each air shower with a feasible accuracy. The system is composed of TKO and CAMAC which are controlled by a micro-computer. Data is recorded in a 2.3 Gbyte 8mm video tape. The time resolution of about 10 sec/day was achieved by use of a GPS and a Rb clock.At present air showerr are triggered at a rate of about 20 Hz. In comparison with a detailed Monte Carlo simulation, it is shown that the mean energy of observed showers is about 20 TeV and showers with energies around or less than 10 TeV could be d … More etected with no serious bias. The angular resolution is shown to be about 1 degree. Only our array can detect such low energy showers with a feasible accuracy, mainly because of high observation level. Both of air Cerenkov detectors and air shower arrays working near the seal level can never observe those gamma-rays because of serious detection biases.A moon shadow by high energy cosmic rays was well observed by our array, with a deficit of about 4.2 sigma. From titis result, the angular resolution is directly estimated to be about 1 degrees.Searches for high energy gamma-rays from Cyg. X-3, Her. X-1 and Crab nebula/pulsar, which include a neurton star and emit powerful X-rays, have been carefully done with negative results. The flux upper limits (95%CL) for them are then estimated to be 2.03x10^<-12>/cm^2. sec, 0.59x10^<-12>/cm^2. sec and 1.48x10^<-12>/cm^2/cm^2. sec, respectively. Gamma-rays from Crab nebula have been observed in TeV region with the Whipple Cerenkov mirrors. This result may be checked in 10 TeV energy region by our experiment after further one year operation. And We need early enlarge the plane of the effective area 3x10^4m^2 Less