First FAMU observation of muon transfer from mu-p atoms to higher-Z elements

TL;DR

This paper reports the first observation of muon transfer from muonic hydrogen atoms to higher-Z elements like carbon dioxide, oxygen, and argon, providing data crucial for hyperfine splitting measurements.

Contribution

It presents the first experimental measurement of muon transfer rates to higher-Z gases from mu-p atoms, advancing the understanding needed for muonic hydrogen hyperfine splitting studies.

Findings

Muon transfer observed to CO2, O2, and Ar.

Transfer rates characterized for non-thermalized mu-p atoms.

Methodology for transfer rate analysis established.

Abstract

The FAMU experiment aims to accurately measure the hyperfine splitting of the ground state of the muonic hydrogen atom. A measurement of the transfer rate of muons from hydrogen to heavier gases is necessary for this purpose. In June 2014, within a preliminary experiment, a pressurized gas-target was exposed to the pulsed low-energy muon beam at the RIKEN RAL muon facility (Rutherford Appleton Laboratory, UK). The main goal of the test was the characterization of both the noise induced by the pulsed beam and the X-ray detectors. The apparatus, to some extent rudimental, has served admirably to this task. Technical results have been published that prove the validity of the choices made and pave the way for the next steps. This paper presents the results of physical relevance of measurements of the muon transfer rate to carbon dioxide, oxygen, and argon from non-thermalized excited mu-p atoms. The analysis methodology and the approach to the systematics errors are useful for the subsequent study of the transfer rate as function of the kinetic energy of the mu-p currently under way.