Nuclei charge measurement by the Alpha Magnetic Spectrometer silicon tracker

Abstract

The Alpha Magnetic Spectrometer (AMS) is a high energy particle detector aboard the International Space Station. AMS precisely measures the fluxes of all cosmic-ray nuclei with charge from Z=1 to Z=28 and beyond. The AMS silicon tracker measures energy deposition of charged particles traversing over nine-layer silicon sensors, from L1 to L9. In this paper, the details of the AMS silicon tracker charge measurement method are presented. The obtained charge resolution of the AMS inner tracker (L2 to L8 combined) is 0.1 charge units for carbon, 0.15 charge units for silicon, and 0.3 charge units for iron nuclei.