The scattering of muons in low Z materials

TL;DR

This study measures muon scattering in various low Z materials, compares results with simulations and theories, and finds discrepancies that impact ionisation cooling predictions for muon accelerators.

Contribution

It provides experimental data on muon scattering in low Z materials and evaluates the accuracy of simulation models and theories in predicting these interactions.

Findings

Geant 4 simulations do not match the data well.

ELMS theory aligns better with liquid hydrogen data.

Ionisation cooling may be more effective than current models predict.

Abstract

This paper presents the measurement of the scattering of 172 MeV/c muons in assorted materials, including liquid hydrogen, motivated by the need to understand ionisation cooling for muon acceleration. Data are compared with predictions from the Geant 4 simulation code and this simulation is used to deconvolute detector effects. The scattering distributions obtained are compared with the Moliere theory of multiple scattering and, in the case of liquid hydrogen, with ELMS. With the exception of ELMS, none of the models are found to provide a good description of the data. The results suggest that ionisation cooling will work better than would be predicted by Geant 4.7.0p01.