Isotopic yields from the reaction 245Cm(n th,f) at the Lohengrin mass separator

Abstract

Isotopic yield measurements for thermal neutron induced fission of 245Cm at the Lohengrin fission-product mass separator are described. Using an ionisation chamber coupled to the Lohengrin mass separator and the stacked foil technique, we measured the isotopic yields from mass A=85 to mass A=115 (near symmetry region) corresponding to nuclear charges Z=33 (As) to Z=47 (Ag). This has considerably extended the data set previously known for the very light fission products providing isotopic yields from A=76 to 94. In the present work, the nuclear charge assignment was performed using the energy loss in a stack of foils of Parylene C, a technique developed and used previously. This allows 4 to 5 nuclear charges per mass to be measured. The global proton odd–even effect calculated from the present measurements is 9.3±0.5%, a value corresponding to the known systematics for the effect as a function of the Coulomb parameter. A study of the global proton odd–even effect as a function of the light fragment kinetic energy was additionally carried out and the intrinsic excitation energy at scission was deduced for different compound nuclei.