Muon Capture inHe3

Abstract

The rate has been measured for capture of negative muons on He 8 to form bound H 3 . The monoenergetic recoil triton was observed in a He 8 gas scintillation target counter, and the rate was normalized to pi-decay electrons observed in surrounding counters. Triton pulses were analyzed in the two dimensions of energy and time with respect to the stopping muon, and with an ultimate energy resolution of 15%, full width at half-maximum, a clean separation could be made between recoil tritons and other muon-associated events. The measured capture rate is 1465±67 sec"" 1 , in good agreement with other experiments and with predictions based on the "standard" theory of muon capture. Simultaneous limits were calculated for the vector and induced pseudoscalar coupling constants, gv* and gp*, using the results of this experiment and of the experiments on muon capture in liquid hydrogen. These are 0.7<gF M /gF^<l-2 and Kgp^/gA^Kil with central values of 0.99 and 11.6, respectively.

Muon capture on deuteron andHe3

“…The experimental situation for reaction (1.2) is much clearer: after a first set of measurements in the early sixties [10][11][12][13], a very precise determination in the late nineties yielded a total capture rate Γ 0 =1496(4) s −1 [14], a value consistent with those of the earlier measurements, although these were affected by considerably larger uncertainties.…”

Induced pseudoscalar coupling of the proton weak interaction

“…VII.B.1 below we discuss the current status of the 3 So far several measurements of the 3 He → 3 H rate have been performed. They comprise the early work of Auerbach et al (1967), Clay et al (1965), Falomkon et al (1963), Zaimidoroga et al (1963), and recent work of Ackerbauer et al (1998).…”

“…(1998) a 3 He gas ionization chamber was used whereas in Falomkon et al (1963) and Clay et al (1965) 3 He ionization chamber with a 15 cm 3 active volume and a 20 Torr gas pressure. The anode plane was segmented to permit the tracking of the incoming muons, the isolation of the recoil tritons, and the definition of the fiducial volume.…”

Muon Capture in Helium-3

“…There have been recent experiments on the p decay 1 of H 3 , muon capture [2][3][4] in He 3 , and on the photodisintegration 5-8 of both nuclei. The electromagnetic form factors 9 have been measured over the range 1<# 2 <8-F~~2, and some data on the inelastic process 10 e+He 3 -> d-\-p-\-e f have been obtained.…”