Slow Muons and Muonium

Abstract: The Paul Scherrer Institut in Switzerland operates the high intensity proton accelerator facility HIPA. A 590 MeV kinetic energy proton beam of presently up to 2.4 mA is sent to target stations producing pions, muons and neutrons for fundamental and applied physics. The beam power of 1.4 MW provides the world's highest intensities of low momentum muons which can be stopped in low mass targets. Rates of surface muons of up to about $10^8$/s are being provided to various unique precision particle physics experiments. Two feasibility studies are ongoing to considerably improve the available muon beams. The high intensity muon beamline, HiMB, could deliver on the order of $10<sup>{10}$/s surface muons and the stopped muon cooler, muCool, aims at a gain factor of $10<sup>{10}$ in phase space quality while sacrificing only less than 3 orders of magnitude in intensity for low energy $\mu<sup>+$. These beams will allow a new generation of precision physics experiments with stopped muons and muonium atoms.