Radiative capture of fast neutrons by 40Ca
1974; Elsevier BV; Volume: 231; Issue: 1 Linguagem: Inglês
10.1016/0375-9474(74)90291-7
ISSN1873-1554
AutoresI. Bergqvist, D. M. Drake, D.K. McDaniels,
Tópico(s)Astronomical and nuclear sciences
ResumoThe radiative capture cross section for the reaction 40Ca(n, γ)41Ca has been measured for the neutron energy range of 6.8–18.2 MeV. A NaI(Tl) anti-Compton spectrometer, a pulsed neutron beam, and time-of-flight techniques were utilized. The γ-ray spectra show strong transitions to the 1f72 ground state and a relatively high intensity of unresolved γ-rays to a group of levels at about 2 MeV, where two 32− states are known to carry the 2p32 strength, and to levels around 4 MeV, which is the centroid energy of the 2p12 strength. Absolute cross sections were determined for these γ-ray transitions as well as the integrated cross section for transitions to bound states of41Ca. Only the cross section for the transition to the f72 ground state of 41Ca shows the resonance behavior predicted by the semidirect (collective) capture theory, but the agreement between the theoretical and measured f72 cross sections is not satisfactory. The measured cross sections for the other γ-ray peaks are almost constant with neutron energy below about 15 MeV, in sharp contrast to the cross sections predicted by the semidirect theory for p32 and p12 transitions.
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