Monte Carlo approach to sequential γ-ray emission from fission fragments

A Monte Carlo simulation of the fission fragment statistical decay based on a sequential neutron followed by γ-ray emission is proposed. The γ-ray energy spectrum is calculated as a function of the mass of the fission fragments and integrated over the whole mass distribution. The prompt γ-ray multiplicity distribution, both the average number of emitted γ rays and the average γ-ray energy as a function of the mass of the fission fragments [respectively, ${\overline{N}}_{\gamma }(A)$ and $\langle {\varepsilon }_{\gamma }\rangle (A)$], are also assessed. The γ-γ correlations emitted from both light and heavy fragments are calculated as well as correlations between γ-ray energies. Results are reported for the neutron-induced fission of ${}^{235}\mathrm{U}$ (at 0.53 MeV neutron energy) and for the spontaneous fission of ${}^{252}\mathrm{Cf}$.

Figure 1

Average total γ-ray energy as a function of FF mass for n(0.53 MeV)$+$${}^{235}\mathrm{U}$ reaction. Points are experimental data from Ref. 17 for thermal neutron-induced fission of ${}^{235}\mathrm{U}$.

Figure 2

Average neutron multiplicity $\overline{\nu }$ as a function of mass number of FF for n(0.53 MeV)$+$${}^{235}\mathrm{U}$ reaction. Points are experimental data from Ref. 15 at thermal incident neutron energy.

Figure 3

Average neutron energy $\langle \varepsilon \rangle$ in the center of mass frame as a function of FF mass for n(0.53 MeV)$+$${}^{235}\mathrm{U}$ reaction. Points are experimental data from Ref. 15 at thermal incident neutron energy.

Figure 4

Average total γ-ray energy as a function of light FF mass for ${}^{252}\mathrm{Cf}$(sf). Points are experimental data from Ref. 21.

Figure 5

Average total energy of γ rays emitted per fission as a function of FF total kinetic energy for n(0.53 MeV)$+$${}^{235}\mathrm{U}$ reaction. Points are experimental data from Ref. 17.

Figure 6

Average energy of γ rays emitted as a function of FF mass at constant total kinetic energy for n(0.53 MeV)$+$${}^{235}\mathrm{U}$ reaction. Points are experimental data from Ref. 17.

Figure 7

Average total γ-ray energy as a function of total kinetic energy at constant fission fragment mass for n(0.53 MeV)$+$${}^{235}\mathrm{U}$ reaction. Points are experimental data from Ref. 17.

Figure 8

Average number of γ rays as a function of FF mass for n(0.53 MeV)$+$${}^{235}\mathrm{U}$ reaction. Points are experimental data from Ref. 17.

Figure 9

Average number of γ rays as a function of FF total kinetic energy for n(0.53 MeV)$+$${}^{235}\mathrm{U}$ reaction. Points are experimental data from Ref. 17.

Figure 10

γ-ray multiplicity distribution for ${}^{252}\mathrm{Cf}$(sf). Experimental fit from Brunson [26].

Figure 11

γ-ray energy spectrum for n(0.53 MeV)$+$${}^{235}\mathrm{U}$ reaction.

Figure 12

γ-ray energy spectrum for ${}^{252}\mathrm{Cf}$(sf).