Ultraslow Positive-Muon Generation by Laser Ionization of Thermal Muonium from Hot Tungsten at Primary Proton Beam

Abstract

Thermal muonium (positive muon ${\ensuremath{\mu}}^{+}$ and electron ${e}^{\ensuremath{-}}$) atoms were produced from the surface of a hot (2300 K) and high purity tungsten foil placed at the primary beam of 500 MeV pulsed protons. Resonant ionization $\left(1s\ensuremath{\rightarrow}2p\ensuremath{\rightarrow}\mathrm{unbound}\right)$ of the thermal muonium with pulsed laser sources was achieved with reference to thermal hydrogen isotopes (D and T) so as to produce a potentially intense ultraslow (as low as 0.2 eV) positive muon beam with an extremely narrow phase-space volume and high stopping density.