Summary
The μ-capture process resulting in the emission of a single neutron is treated as a double two-body process in the giant-dipole-resonance model: μ−+(A, Z)=(A, Z−1)+ν, (A, Z−1)=(A−1,Z−1)+n. The kinematics of the process is studied taking into account the recoil of the (A, Z−1) nucleus. It is found that there exist situations where there is an instantaneous zero-degree angular separation between the neutron and the (A−1,Z−1) nucleus at the time of decay of the (A, Z−1) nucleus. It is conjectured that this might destroy some delicate information about the μ-capture mechanism like asymmetry and polarization, which otherwise might have been carried by the neutrons. In addition to the widths of the fine structure of the neutron asymmetry spectrum and the neutron asymmetry, the Doppler broadening of the (A−1,Z−1) levels, in particular the 6.322 MeV level of15N, is discussed. The predictions of the direct model are systematically compared with those of the giant dipole resonance and with the experimental results.
Riassunto
Il processo di cattura del muone, che ha come risultato l’emissione di un solo neutrone, è trattato come un doppio processo a due corpi nel modello della risonanza di dipolo gigante: μ+(A, Z)=(A, Z−1)+ν, (A, Z−1)=(A−1,Z−1)+n. Si studia la cinematica del processo tenendo conto del rinculo del nucleo (A, Z−1). Si trova che esistono situazioni in cui vi è una separazione angolare istantanea a zero gradi fra il neutrone e il nucleo (A−1,Z−1) al momento del decadimento del nucleo (A, Z−1). Si suppone che ciò possa distruggere alcune delicate informazioni sul meccanismo di cattura del muone come l’asimmetria e la polarizzazione, che altrimenti avrebbero potuto essere portate dai neutroni oltre alle ampiezze della struttura fine dello spettro di asimmetria del neutrone e della asimmetria del neutrone, si discute l’allargamento Doppler dei livelli (A−1,Z−1, in particolare del livello 6.322 MeV del15N. Si confrontano sistematicamente le previsioni del modello diretto con quelle della risonanza dipolare gigante e con i dati sperimentali.
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To speed up publication, the author of this paper has agreed to not receive the proofs for correction.
The neutron asymmetry aspect of this paper was first discussed by the author inBull. Am. Phys. Soc.,15, 24 (1970).
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Pratt, T.A.E.C. The μ-capture mechanism in light complex nuclei. Nuovo Cimento A (1965-1970) 68, 477–496 (1970). https://doi.org/10.1007/BF02758143
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DOI: https://doi.org/10.1007/BF02758143