The calibration and electron energy reconstruction of the BGO ECAL of the DAMPE detector

Abstract

The DArk Matter Particle Explorer (DAMPE) is a space experiment designed to search for dark matter indirectly by measuring the spectra of photons, electrons, and positrons up to 10 TeV. The BGO electromagnetic calorimeter (ECAL) is its main sub-detector for energy measurement. In this paper, the instrumentation and development of the BGO ECAL is briefly described. The calibration on the ground, including the pedestal, minimum ionizing particle (MIP) peak, dynode ratio, and attenuation length with the cosmic rays and beam particles is discussed in detail. Also, the energy reconstruction results of the electrons from the beam test are presented.

A machine learning method to separate cosmic ray electrons from protons from 10 to 100 GeV using DAMPE data

“…The electron energy resolution is based on the MC data from 10 to 100 GeV, which is the sigma from the Gaussian fit, as shown in Figure 3. This resolution is well-matched with the beam test result, indicating a good configuration for the simulation [Zhang et al, 2016].…”

“…The analysis starts with DAMPE 2A ROOT files (Monte Carlo (MC) data from version 5.3.0), which have already been properly calibrated and reconstructed [Zhang et al, 2016]. A flow chart illustrating the machine learning method is shown in Figure 1.…”

The DAMPE experiment: first data from space

“…Also a beam of argon fragments was used for testing the detector response to nuclei. Details of the test-beam results as well as the features of the qualification module can be found in [1][2][3][4][5][6]. Furthermore many tests (namely energy response to MIPs, efficiencies, detector alignment, etc.)…”

Measurement of absolute energy scale of ECAL of DAMPE with geomagnetic rigidity cutoff

“…The migration from bin to its neighbor bins will induce an uncertainty on cosmic ray electron flux measurement and finally affect cut off energy. To estimate this kind of uncertainty, electron spectrum measured with AMS02 [4] is used to generate 1M electron sample and then energy resolution function of DAMPE extracted from beam test [1] is used to tune energy response in G4 simulation, then the matrix between primary energy and . There is an a well agreement between flight data and back tracing above 12GeV when secondary electron contamination is weak, which also demonstrates our particle tracing algorithm is reliable.…”

“…In procedure of Reco, energy hits are reconstructed to final energy by a series of correction algorithms, including side and back end energy leakage correction and dead zone correction [3]. These algorithms are all verified by beam test at CERN in 2014 and 2015 [1]. A more complete description of these algorithms will be presented in section 3.…”