STUDY OF COSMIC GAMMA RAYS AND NUCLEAR INTERACTIONS WITH AIR SHOWERS OBSERVED AT MT.CHACALTAYA

Research Project

Project/Area Number	63043010
Research Category	Grant-in-Aid for Overseas Scientific Research
Allocation Type	Single-year Grants
Section	Field Research
Research Institution	Saitama University
Principal Investigator	MATANO Tsuneo Faculty of Science, Saitama University, Professor, 理学部, 教授 (60008802)
Co-Investigator(Kenkyū-buntansha)	INOUE Naoya Faculty of Science, Saitama University, Research Associate, 理学部, 助手 (40168456) SASAKI Hiroshi Faculty of Science, Koch University, Professor, 理学部, 教授 (80036566) HONDA Ken Faculty of Education, Yamanashi University, Associate Professor, 教育学部, 助教授 (10115321) KAWASUMI Norio Faculty of Education, Yamanashi University, Associate Professor, 教育学部, 助教授 (40020416) TSUSHIMA Itsuro Faculty of Education, Yamanashi University, Associate Professor, 教育学部, 助教授 (30020366)
Project Period (FY)	1987 – 1988
Project Status	Completed (Fiscal Year 1988)
Budget Amount *help	¥1,900,000 (Direct Cost: ¥1,900,000) Fiscal Year 1988: ¥1,900,000 (Direct Cost: ¥1,900,000)
Keywords	Hadron / Air shower / Gamma ray / Emulsion / エマルション / チャカルタヤ
Research Abstract	We are observing the hadronless air showers above 10^<14>eV in order to search gamma-rays from point sources and diffused gamma-rays. phase analysis has been done on hadronless air showers from directions of various point sources(ScoX-1.VelaX-1.SS433.V1223SGR.SN1987a.etc.). observed at Mt.Chacaltaya from 1986 Feb. to 1987 Mar. We could not find any significant excess for these sources. However. we have found a short period excess from ScoX-1 in the latter half of May of 1986. According to the X^2 test for the phase distribution. the probability of the ununiformity is 7.05x10^<-5>. Preliminary results on diffused gamma-rays shows that the excess of hadronless air showers from galactic center is about 3% compared with other directions. Hadrons with energies above 1TeV in air shower cores were caluculated with three-dimensional Monte Carlo simulation in order to compare with our emulsion data observed with the hybrid method(air shower array + emulsion chamber). These caluculations have been done by a high multipicity model according to CKP model and by a model extrapolated from accelerator data. Our experimental results on energy spectrum and ER distributions of high energy hadrons are compared with ones expected from the present calculations.