The DArk Matter Particle Explorer (DAMPE), the first of a series of CAS' Strategic Priority Research Program satellites, was launched into a Sun-synchronous orbit at an altitude of about 500 km in December 2015.
During its approximate 530 days of operation, DAMPE recorded more than 2.8 billion cosmic ray events, including around 1.5 million cosmic ray electrons and positrons (CREs) above 25 GeV. With the data collected by DAMPE, scientists obtained direct measurement of TeV cosmic ray electron spectrum with unprecedentedly high energy resolution and low background.
The data in the energy range of 55 GeV to 2.63 TeV fit much better to a smoothly broken power-law model than to a single power-law model, establishing a spectral break at 0.9 TeV. The post-break decline behavior of the CRE spectrum imposes tight constraint on the dark matter origin of the sub-TeV CREs. There is also tentative evidence for a fine spectral structure at ~1.4 TeV, which needs more data for confirmation.
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