Time & Place: Nov. 15, 3:00pm, Room 9409

Speaker: Prof. Zu-Hao Li (李祖豪), Institute of High Energy Physics

Title: Latest results from the AMS experiment

Abstract: AMS Experiment is a large international collaboration led by
Professor Samuel Ting, a Nobel laureate born in China. AMS detector is a
unique, TeV precision magnetic spectrometer running on space. AMS has
collected over 120 billion charged cosmic ray events in 7 years after
launched in May 2011 and will continue running to the life of
International Space Station beyond 2024. The main physics topics of AMS
are dark matter search, antimatter search and precision measurements of
cosmic rays to TeV range. AMS had published several papers on Physical
Review Letters about measurements of cosmic ray positrons and
antiprotons and arise large interest to dark matter search society. The
latest AMS results on cosmic ray positron measurement provide unique
information on their origin: (a) a significant excess of positrons
starting from 25.2±3.1 GeV; (b) a sharp drop-off of the flux above 284
GeV; and (c) in the entire energy range the positron flux is well
described by the sum of a diffuse term and a new source term of high
energy positrons with a finite energy cutoff of Es ~ 810 GeV. AMS
observed several anti-helium events which might come from anti-universe,
but need more data to confirm the conclusion. Precision measurement on
cosmic ray protons, helium, lithium, beryllium, boron, nitrogen, carbon
and oxygen by AMS provide unique information to understand the origin,
acceleration and propagation of cosmic rays.