Experimental evidence of antiproton reflection by a solid surface

TL;DR

This study provides experimental evidence that low energy antiprotons can be reflected by a solid aluminum surface, challenging the common belief that matter-antimatter interactions are mainly destructive due to annihilation.

Contribution

First experimental demonstration of antiproton reflection from a solid surface, supported by Monte Carlo simulations indicating Rutherford-like scattering as the mechanism.

Findings

A significant fraction of low energy antiprotons reflect off aluminum surfaces.

Reflection occurs primarily via Rutherford-style scattering at energies 1-10 keV.

Results challenge the notion that matter-antimatter interactions are solely destructive.

Abstract

We report here experimental evidence of the reflection of a large fraction of a beam of low energy antiprotons by an aluminum wall. This derives from the analysis of a set of annihilations of antiprotons that come to rest in rarefied helium gas after hitting the end wall of the apparatus. A Monte Carlo simulation of the antiproton path in aluminum indicates that the observed reflection occurs primarily via a multiple Rutherford-style scattering on Al nuclei, at least in the energy range 1-10 keV where the phenomenon is most visible in the analyzed data. These results contradict the common belief according to which the interactions between matter and antimatter are dominated by the reciprocally destructive phenomenon of annihilation.