Muon capture rates in233U,234U,235U,236U,238U, and237Np

Abstract

The time spectra for muon induced fission of 233U, 234U, 235U, 236U, 238U, and 237Npwere measured simultaneously, detecting both fragments in coincidence in a fast multi parallel plate avalanche detector. The observed mean lifetimes r are 68.9___0.3 ns, 70.6+0.2ns, 72.2_0.2ns, 74.3+_0.3ns, 77.0+0.4ns, and 69.8+0.2ns for the above isotopes, respectively. No second time component, tentatively ascribed to a possible fission isomer, was observed. The deduced total capture rates are compared with theoretical predictions.

Muon attachment in prompt fission of237Np

“…Furthermore the result of Belovitskij et al [14] has been used that 90% E1 and 10% E2 transitions contribute to the muon conversion. The capture rate is derived from the Goulard-Primakoff formula [19] using a new parameter set as determined by H~inscheid et al [20]. The capture rate is derived from the Goulard-Primakoff formula [19] using a new parameter set as determined by H~inscheid et al [20].…”

The study of prompt and delayed muon induced fission

“…The results presented here have been obtained in different experiments [9,12,13] performed at the Paul-Scherrer-Institute using the ~E4 muon beam.…”

“…A different experimental technique described earlier in [13] has been applied in order to determine muon capture rates for a chain of isotopes simultaneously and virtually free of systematical errors relative to each other. A multi parallel plate avalanche counter (PPAC) loaded with 6 targets has been used to record the fission events by the identification of both fragments.…”

“…From this measurement [ 13] the ratios of prompt to delayed fission yields have presently been deduced for the isotopes 233U, 234U, 235U, 236U, 238U, and 237Np and are presented in this publication. For more details concerning the experimental arrangements see [9,12,13]. For more details concerning the experimental arrangements see [9,12,13].…”

The probability of prompt and delayed fission of muonic237Np

“…After the muon has reached the 1s-level, it decays or is captured by the nucleus with a capture rate A c. H~n-scheid et al [27] measured the total disappearance rate A, and determined A c. The ratio A JA c can be calculated from [27] to be 1.028 _+ 0.004. Most of the energy released in the basic process p -+p---,n + v u is taken away by the neutrino.…”