The fission yield calculations with Langevin model, Hauser-Feshbach statistical decay, and beta decay

Shin Okumura,Satoshi Chiba,Toshihiko Kawano,Z Ge,H Zhang,Y Chen,W Wang,N Shu

doi:10.1051/epjconf/202023903005

Abstract

We performed the calculations of de-excitation of the primary fission fragments by the Hauser-Feshbach statistical decay followed by the β decay of de-excited fission products. We used the primary fission fragment mass distributions YP(A), total kinetic energy TKE(A), and its width σTKE(A) as input, which were calculated with the Langevin model using macroscopic-microscopic models of the potential energy surface. The prompt neutron multiplicity v̅ and the independent fission product yield (FPY) YI(Z, A, M) and cumulative FPY YC(Z, A, M) are calculated by the Hauser-Feshbach statistical decay and β decay calculations, respectively. The calculated v̅ was overestimated approximately 17% compared to the evaluated data. The decay heats from β and γ were in accordance with the experimental results. The β delayed neutrons yieild was also overestimated.

Highlights

The fission product yield (FPY) has been of great interest for fundamental understanding of the nuclear fission process
The de-excitation calculation has been done using the primary fission fragment that is generated by the Y(A) and total kinetic energy (TKE)(A) fitted to experimental data, together with the ZP model [17, 18, 24]
We conducted the HauserFeshbach de-excitation calculations by employing the fitting parameters obtained from the calculated Y(A) and TKE(A) for 235U(nth, f ) from Ref. [7] into HF3D code [17]

Summary

Introduction

The fission product yield (FPY) has been of great interest for fundamental understanding of the nuclear fission process. The de-excited fragments, called fission products, undergo β decay towards β stability, which produces the decay heat and β delayed neutrons Since these stages of the fission process comprise different physics, no reliable theory has yet been developed that can interpret all fission observables consistent with the primary fission fragment distributions. The fission fragment can be characterised by its yield as a function of mass A, charge Z, isomeric state M, total excitation energy (TXE), and spin J and parity Π, i.e., YP(Z, A, M, TXE, J, Π) Such information cannot be obtained experimentally due to their very short half-lives compared to the experimental timescale, numerous attempts in theoretical descriptions of the nuclear fis-.

Primary fission fragment generation

De-excitation of primary fission fragment

Beta decay of fission product

Results

Conclusion