Search for Primordial Antiparticle with a balloon-borne experiment using a superconducting spectrometer at a solar minimum period

点击翻译按钮获取中文摘要

The research program by using the Balloon-borne Experiment with a Superconducting Spectrometer (BESS) has much progressed with a long duration flight over Antarctica at soar minimum period in 2007～2008 (BESS-Polar II), as summarized as follows : (1) The antiproton spectrum measured shows good consistency with secondary antiproton model calculation. (2) Given this background of secondary antiprotons, cosmologically primary antiprotons have been searched for using the observed antiproton spectrum. The result show no evidence of primary antiprotons that originated from the evaporation of Primordial Black Holes within the obtained statistics. (3) No anti-helium candidate was detected, and a resultant up limit of 7x10E-8 for the abundance ratio of anti-helium/helium in a rigidity range of 1-14 GV by combining all the BESS and BESS-Polar data. This the most stringent limit obtained to date.