30TH INTERNATIONAL COSMIC RAY CONFERENCE A Study of the In-Orbit Particle Rate with the PAMELA Anticoincidence System

Abstract: PAMELA is a satellite-borne experiment designed to study the charged component of the cos-mic radiation of galactic, solar and trapped nature. The main scientific objective is the study of the anti-matter component of cosmic rays over a wide range of energies. PAMELA is mounted on the Resurs DK1 satellite that was launched on June 15th 2006 from the Baikonur cosmodrome and is now on a semipolar (70◦) elliptical (350 × 600 km) orbit. The PAMELA apparatus consists of a permanent magnet silicon spectrometer, an electromagnetic imaging calorimeter, a time of flight system, a scintillator-based anti-coincidence (AC) system, a tail catcher scintillator and a neutron detector. The AC system can be used to reject particles not cleanly entering the PAMELA acceptance. A standalone study of the functionality of the AC system during in-flight operations is presented. The in-orbit particle rates measured by the AC system during the first 6 months of operation are shown. The orbital dependence of the particle rates, the energy and the directionality of the trapped particles are also discussed