Measurement of high energy cosmic rays originated from Vela SNR

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The establishment of the origin of primary cosmic rays is most important theme in cosmic ray physics. To get the final answer it is most important to measure the anisotropy of primary cosmic rays. However, the order of the magnitude of the anisotropy is expected to be 0.1%. Then the observation must be done with sufficient accuracy. This is achieved so to make an observation around the atmospheric depths of air shower maximum developments, that is, with a high altitude air shower array.In this research, we observed air showers at Mt. Chacaltaya (5,200m a. s. l.) to measure the anisotropy due to the cosmic rays emitted from Vela SNR, which is one of the most active astronomical objects in X-and gamma-ray regions.We stated the observation from 2001 after the installment of the equipments. The observation and analyzes were made continuously and preliminary results were presented in the international conference of cosmic rays in Hamburg, Germany 2001 and the meetings of the Physical Societ … More y of Japan.The observed result is summarized as the follows :(1)The enhancement of primary cosmic rays from the galactic disk is observed.(2)The degree of the enhancement around the galactic longitudinal region from 220 to 260 degree is about 0.3%.(3)Our Monte-Carlo simulation on the cosmic rays propagation in the galaxy shows that if Vela SNR is made at 100,000 years ago if the distance of the SNR from the solar system is about 250 pc, the observed result is well explained due to the cosmic rays emitted from the SNR. Since the present accepted values are 10,000 years and 500 pc, respectively, the resent ROSAT results show that the distance is about 250pc and there is another explosion at 100,000 years ago.(3)Our Monte-Carlo simulation on the cosmic rays propagation in the galaxy shows that if Vela SNR is made at 100,000 years ago if the distance of the SNR from the solar system is about 250 pc, the observed result is well explained due to the cosmic rays emitted from the SNR. Since the present accepted values are 10,000 years and 500 pc, respectively, the resent ROSAT results show that the distance is about 250pc and there is another explosion at 100,000 years ago. Less