Measurement of the lifetime and quenching rate of metastable 2S muonic helium ions

• Published in: Physics letters. B 1984-01, Vol.136 (4), p.232-236
• Main Authors: von Arb, H.P., Dittus, F., Heeb, H., Hofer, H., Kottmann, F., Niggli, S., Schaeren, R., Taqqu, D., Unternährer, J., Egelhof, P.
• Format: Article
• Language: English
• Subjects: Atomic and molecular physics; Exact sciences and technology; Exotic atoms and molecules (containing mesons, muons, and other unusual particles); Physics; Studies of special atoms, molecules and their ions; clusters
• ISSN: 0370-2693; 1873-2445
• DOI: 10.1016/0370-2693(84)91152-3

The lifetime of the 2S state in ( μ −4 He) + ions has been measured at He-gas pressures between 50 Torr and 6 atm ( T=300 K). We observed both X-rays from the two-photon 2S→1S transitions as well as delayed K α X-rays associated with radiative quenching. The quenching rate is strongly pressure dependent; it is predominantly a quadratic function of pressure with a measured three-body rate coefficient k=(5.9±0.8)×10 −32 cm 6/ s. At 6 atm, we find τ 2 S