An algorithm to resolve {\gamma}-rays from charged cosmic rays with DAMPE

TL;DR

This paper presents a new method for identifying high-energy gamma rays in DAMPE satellite data, effectively discriminating against charged cosmic rays using Monte Carlo simulations and detector data, enabling better gamma-ray astrophysics studies.

Contribution

The paper introduces a novel gamma-ray identification algorithm for DAMPE that significantly reduces charged cosmic ray contamination using calorimeter and veto detector data.

Findings

Less than 1% contamination from electrons and protons at 10 GeV after selection

Effective identification of known gamma-ray sources in flight data

Preliminary light curves of Geminga pulsar reconstructed

Abstract

The DArk Matter Particle Explorer (DAMPE), also known as Wukong in China, launched on December 17, 2015, is a new high energy cosmic ray and {\gamma}-ray satellite-borne observatory in space. One of the main scientific goals of DAMPE is to observe GeV-TeV high energy {\gamma}-rays with accurate energy, angular, and time resolution, to indirectly search for dark matter particles and for the study of high energy astrophysics. Due to the comparatively higher fluxes of charged cosmic rays with respect to {\gamma}-rays, it is challenging to identify {\gamma}-rays with sufficiently high efficiency minimizing the amount of charged cosmic ray contamination. In this work we present a method to identify {\gamma}-rays in DAMPE data based on Monte Carlo simulations, using the powerful electromagnetic/hadronic shower discrimination provided by the calorimeter and the veto detection of charged particles provided by the plastic scintillation detector. Monte Carlo simulations show that after this selection the number of electrons and protons that contaminate the selected {\gamma}-ray events at $\sim10$ GeV amounts to less than 1% of the selected sample. Finally, we use flight data to verify the effectiveness of the method by highlighting known {\gamma}-ray sources in the sky and by reconstructing preliminary light curves of the Geminga pulsar.