Preliminary Results from Recent Measurements of the Antiprotonic Helium Hyperfine Structure

TL;DR

This study reports precise measurements of the hyperfine structure of antiprotonic helium, providing data that tests CPT invariance and refines the antiproton magnetic moment with high accuracy.

Contribution

First precise experimental measurement of antiprotonic helium hyperfine structure that improves the accuracy of the antiproton magnetic moment and tests CPT symmetry.

Findings

Measurement precision is 60 times better than previous QED calculations.

No density or power dependence observed in the measurements.

Results are consistent with theoretical predictions, enabling improved parameter estimation.

Abstract

We report on preliminary results from a systematic study of the hyperfine (HF) structure of antiprotonic helium. This precise measurement which was commenced in 2006, has now been completed. Our initial analysis shows no apparent density or power dependence and therefore the results can be averaged. The statistical error of the observable M1 transitions is a factor of 60 smaller than that of three body quantum electrodynamic (QED) calculations, while their difference has been resolved to a precision comparable to theory (a factor of 10 better than our first measurement). This difference is sensitive to the antiproton magnetic moment and agreement between theory and experiment would lead to an increased precision of this parameter, thus providing a test of CPT invariance.