A 280 ml liquid hydrogen target has been constructed and tested for the MUSE experiment at PSI to investigate the proton charge radius via simultaneous measurement of elastic muon-proton and elastic electron-proton scattering. To control systematic uncertainties at a sub-percent level, strong constraints were put on the amount of material surrounding the target and on its temperature stability. The target cell wall is made of 120μm-thick Kapton, while the beam entrance and exit windows are made of 125μm-thick aluminized Kapton. The side exit windows are made of Mylar laminated on aramid fabric with an areal density of 368g/m2. The target system was successfully operated during a commissioning run at PSI at the end of 2018. The target temperature was stable at the 0.01 K level. This suggests a density stability at the 0.02% level, which is about a factor of ten better than required.
@article{arxiv.1907.03022,
title = {A Liquid Hydrogen Target for the MUSE Experiment at PSI},
author = {P. Roy and S. Corsetti and M. Dimond and M. Kim and L. Le Pottier and W. Lorenzon and R. Raymond and H. Reid and N. Steinberg and N. Wuerfel and K. Deiters and W. J. Briscoe and A. Golossanov and T. Rostomyan},
journal= {arXiv preprint arXiv:1907.03022},
year = {2019}
}