Precision measurement of antiproton to proton ratio with the Alpha Magnetic Spectrometer on the International Space Station

TL;DR

This paper reports a precise measurement of the antiproton-to-proton flux ratio in cosmic rays over a wide rigidity range, revealing a rigidity-independent ratio above 60 GV, challenging traditional secondary flux models.

Contribution

It provides the first high-precision measurement of the antiproton to proton ratio up to 450 GV using AMS data, with implications for cosmic ray propagation models.

Findings

Antiproton to proton ratio is constant above 60 GV.

Results challenge traditional secondary antiproton flux models.

Data covers rigidity from 1 to 450 GV.

Abstract

A precision measurement by AMS of the antiproton-to-proton flux ratio in primary cosmic rays in the absolute rigidity range from 1 to 450 GV is presented based on $3.49\times10^5$ antiproton events and $2.42\times10^9$ proton events. Above $\sim60$ GV the antiproton to proton flux ratio is consistent with being rigidity independent. A decreasing behaviour is expected for this ratio considering the traditional models for the secondary antiproton flux.