Regular Article – Experimental Physics
Prompt emission of -rays and neutrons from the fast neutron induced fission of Th at neutron energies near and above the fission threshold
Nuclear Physics Division, Bhabha Atomic Research Centre, Trombay, 400085, Mumbai, India
2 Homi Bhabha National Institute, Anushaktinagar, 400094, Mumbai, India
Accepted: 31 October 2022
Published online: 10 November 2022
Measurements of prompt fission -rays and neutrons emitted in the fast neutron induced fission of Th have been carried out at incident neutron energies of 1.5 MeV, 2.1 MeV and 2.8 MeV. The -rays were recorded using two scintillation detectors in coincidence with a twin section fission trigger ionisation chamber while the neutrons were detected using two EJ301 liquid scintillation detectors. The energy spectra of -rays were obtained after unfolding the detected pulse height spectrum using the response matrix of the detectors. The extracted prompt fission -ray spectra for Th(n,f) when compared with the existing data of Cf(sf),Pu(n,f) and U(n,f), showed noticeably lower intensity of photons at energies less than 0.7 MeV. No significant excitation energy dependence of the spectral characteristics of prompt fission -ray spectra for Th(n,f) has been observed. The time-of-flight spectra measured using EJ301 detectors with respect to the twin section fission trigger chamber were used to determine the prompt fission neutron energy spectra at all the three incident neutron energies mentioned above. The measured spectra were then fitted using Maxwell and Watt parametrizations to derive the average prompt fission neutron energy. It is found that GEF describes neutron data well, but fails to corroborate with gamma data.
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