²³³U mass yield measurements around and within the symmetry region with the ILL Lohengrin spectrometer

Abstract

Abstract. The study of fission yields has a major impact on the characterization and understanding of the fission process and is mandatory for reactor applications. The LPSC in collaboration with ILL and CEA has developed a measurement program on fission fragment distributions at the Lohengrin spectrometer of the ILL, with a special focus on the masses constituting the heavy peak. We will present in this paper our measurement of the very low fission yields in the symmetry mass region and the heavy mass wing of the distribution for 233 U thermal neutron induced fission. The difficulty due to the strong contamination by other masses with much higher yields will be addressed in the form of a new analysis method featuring the required contaminant correction. The apparition of structures in the kinetic energy distributions and possible interpretations will be discussed, such as a possible evidence of fission modes.

Measurements of Fission Products Yields with the LOHENGRIN mass spectrometer at ILL

“…The local odd-even effect [13] give some information on the pairs breaking but also on the neutron emission process. An experimental program on isomeric ratios (IRs) measurements was developed since 2012 [19]. Especially a focus on the evolution of IR as function of fission product kinetic energy was made [20,21].…”

Theoretical investigation of fission fragment kinetic energy distributions in the symmetric mass region for233U(nth,f)

“…The ND2016 difference in the descent to the symmetry region seems to be coming from the appearance of a tail at low kinetic energy. It has been shown that this component is the consequence of a change of the fission fragment ionic charge due to their collision with the LOHENGRIN residual gas [9,11]. In order to remove this undesired component, an indicator of contamination as well as a procedure to correct the kinetic energy were developed [9,11].…”

“…It has been shown that this component is the consequence of a change of the fission fragment ionic charge due to their collision with the LOHENGRIN residual gas [9,11]. In order to remove this undesired component, an indicator of contamination as well as a procedure to correct the kinetic energy were developed [9,11]. Nevertheless this component still persists and simple generalisation tends to confirm the consistency of these structures [9,11].…”

“…In order to remove this undesired component, an indicator of contamination as well as a procedure to correct the kinetic energy were developed [9,11]. Nevertheless this component still persists and simple generalisation tends to confirm the consistency of these structures [9,11].…”