Speaker
Description
The FAMU collaboration aims to measure the hyperfine splitting (hfs) of the muonic hydrogen in the ground state, contributing to the understanding of the proton magnetic structure. The Zemach radius of the proton can be estimated from the hfs measurement with an accuracy better than 1%.
The experiment is conducted at the ISIS facility of the Rutherford Appleton Laboratory (UK) at the RIKEN Port1 beamline, where a pulsed muon beam is directed into an 8-bar hydrogen gas target. The 1S hyperfine splitting (hfs) transition is stimulated irradiating the muonic hydrogen with a tunable mid-infrared laser (~6788 pm). The target also contains a small amount of oxygen, and if the hfs transition occurs, an increase in characteristic X-rays from muonic oxygen is detected. This increase is caused by the increased transfer of the muon from hydrogen to oxygen.
The core of the experiment is the pulsed laser, specially developed by INFN Trieste for this application. This laser is unique worldwide because of its tunability, energy, and spectral purity.
The detector system consists of 34 LaBr scintillating crystals read by photomultiplier tubes and silicon photomultipliers and combines excellent timing performance with high energy resolution. A dedicated muon beam monitor ensures accurate beam diagnostics and data normalization.
This contribution will offer an update on current status of the experiment, its performance, and the progresses made in data analysis.
