The First Result from the AMS-02 experiment -

positron ratio in the primary cosmic rays

Prof. Yuan-Hann Chang (張元翰 教授)

Abstract

    The Alpha Magnetic Spectrometer, AMS, is a general purpose particle physics detector in space. It was installed on the International Space Station on 19 May, 2011. The first AMS result is based on 25 billion cosmic ray events collected during the first 18 months of operation. A precision measurement of the positron fraction in primary cosmic rays in the range from 0.5 to 350 GeV is presented. The spectrum shows a steady increase of the positron ratio from 10 to ~250 GeV, with no observable structure or anisotropy.

    This talk will introduce the AMS detector and its operation in space, followed by details of the analysis towards the positron ration measurement. Some implications of these new results are also discussed.

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