Measurement of the cosmic-ray antiproton spectrum at solar minimum with a long-duration balloon flight over Antarctica

TL;DR

This study measures the cosmic-ray antiproton spectrum during solar minimum with a balloon flight over Antarctica, confirming secondary origin and finding no evidence for primordial black hole evaporation.

Contribution

It provides the first detailed measurement of the antiproton spectrum at solar minimum using a long-duration balloon flight, testing models of primary antiproton sources.

Findings

Measured antiproton spectrum from 0.17 to 3.5 GeV.

Data consistent with secondary antiproton calculations.

No evidence found for primordial black hole evaporation.

Abstract

The energy spectrum of cosmic-ray antiprotons from 0.17 to 3.5 GeV has been measured using 7886 antiprotons detected by BESS-Polar II during a long-duration flight over Antarctica near solar minimum in December 2007 and January 2008. This shows good consistency with secondary antiproton calculations. Cosmologically primary antiprotons have been investigated by comparing measured and calculated antiproton spectra. BESS-Polar II data show no evidence of primary antiprotons from evaporation of primordial black holes.