Matsushiro Underground Cosmic-Ray Observatory (2S0 m. w. e. Depth) and the Observation of High Energy (r1012 /!V) Cosmic Ray Intensity Variation

A new underground cosmic-ray observatory was opened in Matsushiro, Nagano City, Japan on March 22, 1984, and a multi-directional muon telescope has been installed at an effective vertical depth of 220 m. w. e. underground. The telescope consists of 50 plastic scintillation detectors totally, arranged in two layers of 25 detectors each and has 17 directional channels of observation. We have made the continuous observation of the intensity variation of cosmic ray muons (median primary energies of detection d1012 eV) since that date. The intensity has been recorded every hour, and the average muon countingrates are; ～8.7×10t counts per hour for a wide-angle vertical telescope (two-fold coincidence between upper and lower arrays of detectors) and ～2.0×10t counts per hour for a vertical component-telescope, for example. In the present report, we describe briefly the underground observatory of Matsushiro and its surroundings, including the underground tunnel, the muon detector, the multi-directional telescope constructed and some of its related characteristics. We also present some of the observed intensity variations of cosmic ray muons for a full five-year period from April 1984 through March 1989 and discuss preliminarily the analyzed results of them in solar and sidereal time.Article信州大学理学部紀要 24(1): 1-46(1989)departmental bulletin pape

Japan-Australia Cooperative Observation of North-South Asymmetry in Intensity Variation of High Energy Cosmic Rays(r1012/!V)

Japan-Australia cooperative observation between Shinshu University and University of Tasmania commenced in December 1991 to measure the north-south (N-S) asymmetry in the intensity variation of high energy cosmic rays (d1012/!V). In the project an emphasis is particularly laid on the measurement of the N-S asymmetric sidereal anisotropy to reveal three-dimensional nature of anisotropies of galactic origin. This is the first bi-hemisphere comparative underground observation, and was motivated on the basis of recent data obtained by multi-directional telescopes at Matsushiro (220 m.w.e. depth underground) of Shinshu University and at Sakashita (80 m.w.e. depth underground) of Nagoya University. The data show that at rigidities ～400 GV to ～1 TV, the observed diurnal amplitudes appear to increase as the detector's latitude of viewing moves southward, suggesting its N-S asymmetric nature of the sidereal time variation. The evidence is, however, limited only in the northern hemisphere, and has no positive confirmation yet in the southern hemisphere. To get further information about the N-S asymmetric anisotropy, Japanese group proposed the bi-hemisphere comparative observation with similar equipments and at similar rigidities. Two cosmic ray groups of Shinshu University and University of Tasmania, Australia agreed with each other, both financially supported, to push a joint project and open a pair underground stations; one at Matsushiro (in operation since 1984), Japan and the other at Liapootah (newly constructed) in Tasmania, Australia. The Liapootah underground station (42°20'S, 146°28'E) is situated in a central part of Tasmania Island, and has such characteristics as; located at almost conjugate position to Matsushiro (36°32' N, 138°01' E), at almost comparable underground depth (approximately 154 m.w.e.) to Matsushiro (220 m.w.e. depth), and with almost similar rigidities of primaries (～500 GV-1 TV). The muon telescope used at Liapootah is quite similar to that at Matsushiro; of plastic scintillators viewed with double photomultipliers and of multi-directional. Nearly equal counting-rates of muons are obtained at two stations ; ～2・ 10t /hr for the vertical telescope, and 5-7・103/hr for the inclined telescope (towards north-, south-, east- and west-direction). In the present paper, we describe the underground site and the muon telescope at Liapootah in some details, with a comparsion of those at Matsushiro. All the electronics system including data sending are controlled by means of the micro-computer system via public telephone lines from both universities at Hobart and Matsumoto.Article信州大学理学部紀要 27(2): 47-78(1993)departmental bulletin pape

Differences in muscle power between the dominant and nondominant upper limbs of baseball players

We examined the differences in muscle power between the dominant and nondominant upper limbs of 33 healthy, right-handed, university baseball players (mean age, 20.4±1.1 years) with an average baseball experience >11 years. After measuring maximal voluntary contraction (MVC) of hand grip, elbow flexion, and shoulder internal rotation in both upper limbs, the muscle power of each joint was measured at 40%, 50%, and 60% MVC. No significant differences were observed in the main factors affecting MVC and elbow flexion power loads between dominant and nondominant upper limbs. For handgrip power, load factors at 40% MVC in the dominant hand were lower than those at 60% MVC in the same hand and those at 50% and 60% MVC in the nondominant hand. Significant differences were observed in shoulder internal rotation power between dominant and nondominant upper limbs, with the dominant limb having greater power at all loads. Correlations between muscle power of both upper limbs for handgrip and elbow flexion were significant and moderately high at all loads. For shoulder internal rotation power, the degree of correlation was significant and moderately high at 40% MVC but low to moderate at 50% and 60% MVC. Therefore, baseball players have marked lateral dominance in shoulder internal rotation power unlike handgrip and elbow flexion power, although the relationship between shoulder internal rotation muscle powers of both upper limbs becomes lower with increasing load. The dominance of muscle power of each joint varied even in the same upper limb. It is thus beneficial for baseball players to train with even loads on both arms or adopt simultaneous workout of both arms after adjusting for strength differences. © 2013 National Strength and Conditioning Association