https://doi.org/10.1140/epja/s10050-020-00127-7
Regular Article - Experimental Physics
Measurement of prompt fission neutron and gamma spectra in the fast neutron induced fission of 
Th
1
Nuclear Physics Division, Bhabha Atomic Research Centre, Trombay, Mumbai, 400085, India
2
Homi Bhabha National Institute, Anushaktinagar, Mumbai, 400094, India
* e-mail: rgthomas@barc.gov.in
Received:
24
October
2019
Accepted:
13
March
2020
Published online:
21
April
2020
Measurements of prompt fission neutrons and gamma rays spectra have been carried out in the fast neutron induced fission of Th at an average neutron energy of 2.6 MeV. The energy spectrum of neutrons is obtained from the time-of-flight spectrum measured using EJ301 detectors with respect to a twin section trigger fission chamber, while the energy spectrum of prompt gamma rays is obtained after unfolding the measured pulse height spectrum using the response matrix of the CeBr
detectors. The Maxwellian temperature obtained from the prompt fission neutron spectrum is found to be 1.22 ± 0.03 MeV. The low efficiency and limited resolution of the gamma set up, in addition to the low cross section of the reaction which result into poor statistics, made the reliable extraction of the detailed fine structure in the prompt fission gamma spectrum difficult. However, a reasonable estimate of the average gamma energy could be obtained as 0.91 ± 0.04 MeV. The extracted observables are then compared with the values predicted by the GEF model. It is found that, while the measured prompt fission neutron spectrum and the extracted Maxwellian temperature agree reasonably well when compared with the predictions of the GEF model, the average gamma ray energy from the measured prompt fission gamma spectrum is found to be lower by 
17
from the predictions of the model. A rough estimate of average neutron and gamma multiplicities are also obtained from the measurements.
© Società Italiana di Fisica and Springer-Verlag GmbH Germany, part of Springer Nature, 2020
