Collision Induced Relaxations within the Antiprotonic Helium Hyperfine Structure

TL;DR

This paper presents the first experimental measurement of inelastic spin exchange collision rates in antiprotonic helium's hyperfine structure, comparing results with theoretical predictions and simulations.

Contribution

It provides the first measurement of inelastic collision rates between hyperfine levels in antiprotonic helium, validating and refining theoretical models.

Findings

Measured inelastic collision rate qualitatively agrees with theory

Results suggest the actual collision rate is likely higher than measured

Simulation comparison indicates slight underestimation of the rate

Abstract

We report the first measurements of the inelastic spin exchange collision rate between the Hyperfine (HF) levels of antiprotonic helium. We measure the time dependent evolution of the (37, 35) substates to obtain an inelastic collision rate which qualitatively agrees with recent theoretical calculations. We evaluate these results by using the obtained rate as a parameter in a rigorous simulation which we then compare to to previously measured data. We find that our measurement slightly underestimates the collision rate and therefore conclude that the actual value most probably falls within the upper, rather than lower, limit of the error.