Target Studies for Surface Muon Production

TL;DR

This study investigates using neutron spallation targets to enhance surface muon production, finding optimized geometries and materials can significantly increase muon yields for physics experiments.

Contribution

It demonstrates that target geometry and material choices can substantially improve surface muon rates, with detailed simulations guiding optimal designs.

Findings

Backward spallation targets outperform standard targets by over 7 times in muon yield.

Optimized rotated slab targets increase muon rates by 30-60%.

Novel materials like boron carbide can add an extra 10% gain.

Abstract

Meson factories are powerful drivers of diverse physics programmes. With beam powers already in the MW-regime attention has to be turned to target and beam line design to further significantly increase surface muon rates available for experiments. For this reason we have explored the possibility of using a neutron spallation target as a source of surface muons by performing detailed Geant4 simulations with pion production cross sections based on a parametrization of existing data. While the spallation target outperforms standard targets in the backward direction by more than a factor 7 it is not more efficient than standard targets viewed under 90{\deg}. Not surprisingly, the geometry of the target plays a large role in the generation of surface muons. Through careful optimization, a gain in surface muon rate of between 30 - 60% over the standard "box-like" target used at the Paul Scherrer Institute could be achieved by employing a rotated slab target. An additional 10% gain could also be possible by utilizing novel target materials such as, e.g., boron carbide.