Grant-in-Aid for international Scientific Research
|Allocation Type||Single-year Grants |
|Research Institution||The University of Tokyo |
YUDA Toshinori Prof., Institute for Cosmic Ray Research, Univ. of Tokyo, 宇宙線研究所, 教授 (60092368)
任 敬儒 中国科学院, 高能物理研究所, 教授
KAJINO Fumiyoshi Associate Prof., Faculty of Science, Konan Univ., 理学部, 助教授 (50204392)
YAMAMOTO Yoshiaki Prof., Faculty of Science, Konan Univ., 理学部, 教授 (70068112)
SUGIMOTO Hisahiko Associate Prof., Shonan Inst. of Technology, 教養課程物理, 助教授 (00121070)
TORII Shoji Assistant, Faculty of Engineering, Kanagawa Univ., 工学部, 助手 (90167536)
KASAHARA Katsuaki Associate Prof., Faculty of Engineering, Kanagawa Univ., 工学部, 助教授 (00013425)
MIZUTANI Kohei Associate Prof., Faculty of Science, Saitama Univ., 理学部, 助教授 (60008844)
HOTTA Naoki Assistant, Faculty of Education, Utsunomiya Univ., 教育学部, 助手 (60157039)
OHTA Itaru Prof., Faculty of Education, Utsunomiya Univ., 教育学部, 教授 (30008023)
NANJO Hirotada Associate Prof., Faculty of Science, Hirosaki Univ., 理学部, 助教授 (00106840)
JING-RU Ren Prof., Inst. of High, Energy Phys., Academia Sinica
|Project Period (FY)
Completed(Fiscal Year 1991)
|Budget Amount *help
¥3,000,000 (Direct Cost : ¥3,000,000)
Fiscal Year 1991 : ¥3,000,000 (Direct Cost : ¥3,000,000)
|Keywords||Tibet / Yangbajing / Air shower array / Origin of cosmic ray / Neutron star / Scintillation detector / Cyg. X-3 / Crab nebula|
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
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