Design and Installation Status of the Liquid Hydrogen Cryotarget Assembly for the MUSE Experiment*

A fundamental challenge faced by the scientific community is to resolve the proton radius puzzle: the unexplained discrepancy observed between muon spectroscopic measurements and atomic measurements of the proton charge radius. The MUon Scattering Experiment (MUSE) at the Paul Scherrer Institute is likely to play an instrumental role towards resolving this puzzle. It will be the first elastic scattering experiment that will use a simultaneous beam of muons and electrons at very low Q^{2}, thus allowing a direct comparison of the proton radius from the two leptonic probes at a sub-percent level. An essential and arguably the most complex part of MUSE is the liquid hydrogen cryotarget assembly. Its design is guided by several experimental and safety constraints. The experiment primarily requires a liquid hydrogen target of very stable density, a vertically movable ladder consisting of three targets in addition to the liquid hydrogen target for alignment and background studies, and large vacuum windows to provide high acceptance. In this talk, I will present the design of the cryotarget assembly, the fabrication technique for the target cells and safety tests. I will also discuss the installation status of the cryotarget assembly.