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

The FAMU experiment aims to measure precisely the hyperfine splitting of the muonic-hydrogen atom ground state. A preliminary measurement of the transfer rate of muons from hydrogen to heavier gases is needed. In June 2014, the FAMU pressurized gas target was exposed to the low energy pulsed muon beam at the RIKEN RAL (Rutherford Appleton Laboratory, UK) muon facility. The main goal of the test was the characterization of both the target and the X-ray detectors. In this paper the physics results of the test are presented. The transfer rates from hydrogen to CO2, oxygen, and argon are measured even if in a non-thermalized and excited mu-p system. The methodology and the systematic study approach are useful for the data analysis of the measurement of the transfer rate as function of the mu-p kinetic energy currently under study.