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

中国物理学家在西藏羊八井（海拔4300米）建造了一个新的空气簇射阵列，以寻找来自天鹅座等天体点源的超高能伽马射线。X-3-3为了研究高能宇宙线的起源和加速机制，该阵列由65个通道的闪烁探测器组成，其中49个探测器的面积为0.5mX^2，排列成15 m的网格状，以测量每一次空气簇射的到达时间和粒子密度。该系统由TKO和CAMAC两部分组成，由微机控制。数据记录在2.3 GB 8 mm录像带中。利用GPS和铷钟实现了约10秒/天的时间分辨率。目前，空气电离室的触发速率约为20 Hz。与详细的MonteCarlo模拟结果比较表明，观测到的簇射的平均能量约为20 TeV，而能量在10 TeV左右或以下的簇射可以观测到 关于我们 没有严重的偏见。角分辨率显示为约1度。只有我们的阵列可以检测到这样的低能量阵雨与可行的精度，主要是因为高的观测水平。由于探测偏差严重，在密封层附近工作的空气切伦科夫探测器和空气簇射阵都无法观测到这些γ射线，我们的阵列很好地观测到了高能宇宙线的月影，偏差约为4.2 σ。根据这一结果，直接估算出天鹅座高能γ射线的角分辨率约为1度/秒。X-3、Her. X-1和蟹状星云/脉冲星，其中包括一颗神经元星星，并发出强大的X射线，已经被仔细地做了负面的结果。它们的通量上限（95%CL）估计为2.03 × 10 ^<-12>/cm ^2。秒，0.59 × 10 ^<-12>/cm ^2。秒和1.48 × 10 ~ 4<-12>/cm ~ 2/cm ~ 2。sec，分别。用维普莱切伦科夫镜观测了蟹状星云TeV区的γ射线。这一结果在10 TeV能区可由我们的实验进一步验证。我们需要尽早扩大有效面积的平面3x10^4m^2减

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