Anomalies in the Charge Yields of Fission Fragments from the U-238(n, f) Reaction

作者：Wilson J N^*; Lebois M; Qi L; Amador Celdran P; Bleuel D; Briz J A; Carroll R; Catford W; De Witte H; Doherty D T; Eloirdi R; Georgiev G; Gottardo A; Goasduff A; Hadynska Klek K; Hauschild K; Hess H; Ingeberg V; Konstantinopoulos T; Ljungvall J; Lopez Martens A; Lorusso G; Lozeva R; Lutter R; Marini P; Matea I; Materna T; Mathieu L; Oberstedt A; Oberstedt S; Panebianco S; Podolyak Zs; Porta A; Regan P H; Reiter P; Rezynkina K; Rose S J; Sahin E

来源：Physical Review Letters, 2017, 118(22): 222501.

DOI：10.1103/PhysRevLett.118.222501

Fast-neutron-induced fission of U-238 at an energy just above the fission threshold is studied with a novel technique which involves the coupling of a high-efficiency.-ray spectrometer (MINIBALL) to an inversekinematics neutron source (LICORNE) to extract charge yields of fission fragments via gamma-gamma coincidence spectroscopy. Experimental data and fission models are compared and found to be in reasonable agreement for many nuclei; however, significant discrepancies of up to 600% are observed, particularly for isotopes of Sn and Mo. This indicates that these models significantly overestimate the standard 1 fission mode and suggests that spherical shell effects in the nascent fission fragments are less important for low-energy fastneutron-induced fission than for thermal neutron-induced fission. This has consequences for understanding and modeling the fission process, for experimental nuclear structure studies of the most neutron-rich nuclei, for future energy applications (e.g., Generation IV reactors which use fast-neutron spectra), and for the reactor antineutrino anomaly.

• 出版日期2017-6-1