The MuCap experiment at the Paul Scherrer Institute has measured the rate ΛS of muon capture from the singlet state of the muonic hydrogen atom to a precision of 1%. A muon beam was stopped in a time projection chamber filled with 10-bar, ultrapure hydrogen gas. Cylindrical wire chambers and a segmented scintillator barrel detected electrons from muon decay. ΛS is determined from the difference between the μ- disappearance rate in hydrogen and the free muon decay rate. The result is based on the analysis of 1.2×1010 μ- decays, from which we extract the capture rate ΛS=(714.9±5. 4stat±5.1syst) s-1 and derive the proton's pseudoscalar coupling gP(q02=-0.88mμ2)=8.06±0.55.
ASJC Scopus subject areas
- Physics and Astronomy(all)