OBSERVATION AND ITS ANLYSIS OF MUON SHOWERS AT DEEP UNDERGROUND (APPROXIMATELY 200 M.W.E. IN DEPTH)

Research Project

Project/Area Number	59540152
Research Category	Grant-in-Aid for General Scientific Research (C)
Allocation Type	Single-year Grants
Research Field	核・宇宙線・素粒子
Research Institution	FACULTY OF SCIENCE, SHINSHU UNIVERSITY
Principal Investigator	MORI SATORU FACULTY OF SOIENCE, SHINSHU UNIVERSITY, 理学部, 教授 (50020649)
Co-Investigator(Kenkyū-buntansha)	ICHINOSE MASAOKI FACULTY OF SCIENCE, SHINSHU UNIVERSITY, 教養部, 教授 (30021207) YASUE SHINICHI FACULTY OF SCIENCE, SHINSHU UNIVERSITY, 理学部, 助手 (80020668) SAGISAKA SHUJI FACULTY OF SCIENCE, SHINSHU UNIVERSITY, 理学部, 助教授 (90020643)
Project Period (FY)	1984 – 1986
Project Status	Completed (Fiscal Year 1986)
Budget Amount *help	¥2,300,000 (Direct Cost: ¥2,300,000) Fiscal Year 1986: ¥400,000 (Direct Cost: ¥400,000) Fiscal Year 1985: ¥400,000 (Direct Cost: ¥400,000) Fiscal Year 1984: ¥1,500,000 (Direct Cost: ¥1,500,000)
Keywords	Cosmic ray sidereal anisotropy / underground observation / ミューオンシャワー
Research Abstract	Since the discovery of cosmic rays, the observations of sidereal anisotropy of cosmic rays has been one of the most important problems to explore the origin of cosmic rays and its propagation though the galactic, the heliospheric and the interplanetary space. The observations have mostly been made on ground-based, then its rigidity ranges are <10^(10)> - <10^(14)> V, depending on the location of observations and also on its detection method. A energy or rigidity spectrum of anisotropy may be of prime importance; in low rigidity regions ( <10^(10)> - <10^(11)> V) anisotropy being contaminated by spurious variations, while in high rigidity regions (> <about> <10^(12)> V), the observed anisotropy is free of them. So far, however, the observed amplitudes have been believed to be small ( <about> 0.05%). The present project started along with this presumption; by dtecting muon showers at the underground, whose median primary rigidity may be high enough to detect the anisotropy. In the course o … More f the present observations, our another observation has revealed that one of multi-directional muon telescopes at matsushiro measured larger amplitudes ( <about> 0.15%) than those so far obtained. Note that the amplitude is more than double of air-shower measurements (> <10^(13)> eV) and several times as large as those by muon telescopes. Also note that the south-pointing telescope can scan almost the equatorial plane or rather southerly latitudes asymptotically. We believe this observation is something new and may suggest the existence for the heavy anisotropic flows of cosmic rays near the equatorial plane. In the present project, we are not able to obtain any new informations of sidereal diurnal anisotropy (its amplitude <about> 0.07% with <about> 23.3 hr LST phase). We think that this may be due to the present detection method of omni-directional measurement. Our accompanying result may suggest that directional muon shower measurement, in particlur in the directions of north and south, migh be preferable for measuring sidereal anisotropy. Less