Abstractions

摘要

Galactic cosmic rays -high-energy charged particles that result from hugely energetic processes - are one of the few ways to directly measure matter from outside the Solar System. In 2000, Jin Chang, now an astrophysicist at the Purple Mountain Observatory in Nanjing, China, and a group of international colleagues first detected an excess of high-energy cosmic-ray electrons using the Advanced Thin lonization Calorimeter (ATIC). The instrument was sent on helium balloons to measure the composition and energy spectra of cosmic rays 35 kilometres above Antarctica.