Study on sidereal daily variation of primary cosmic rays and particle acceleration mechanism in Solar flare

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Huge Muon detectors consists of 16 independent units have been newly constructed in Ooty, South India by 1997 end. Its total fiducial area is about 560 m^2. It can detect the cosmic ray muons energy above 1GeV.The counting rate is recorded at every one second. This is the largest muon detector in the world for the purpose of modulation measurement. These detectors have been modified to enable the angle measurement of individual muons in each 10 seconds using this Grant in Aide. We wish to study the sidereal variation on primary cosmic rays above 100 GeV, the structure of interplanetary magnetic field and shock front of plasma created by energetic Solar flare. At this moment angle measurement of all the 16 units (560 m^2) are operational and the observation is going on. We have analyzed part of these data so far and could confirm that the performance of our muon detectors is quite successful. The followings are some of the results from the latest observation.1. We have analyzed on solar … More daily variation and detected the peak at direction of 13.5 hour (Local Time) with amplitude of about 0.4%. This can be well understood by so called Diffusion-Convection Model and influence of the Earth's magnetic field.2. We analyzed the data by classifying IMF direction and could observe the sidereal variation by Swinsson Flaw (about 0.15%). This is mainly due to radial asymmetry of cosmic ray density.3.There were two anomalies in sidereal daily variation, one is the deficit by Loss corn and another is excess by Tail in effects. These amplitudes are about 0.1%. Since our detector is located near equator, we could get these two anomalies simultaneously.We have been continuing analysis on new data from angle measurements. We have completed the analysis of total counts measurements from April 1998 to March 2000 so far. We realized that there are about 2 hour difference between 1998 data set and 1999 data set in the position of these sidereal anomalies. So the cause of this discrepancy is under close investigation now. Same time we are analyzing the time and angular profile of Forbush Decrease. We would like to continue our present observation and accumulate the data. Less