Isomeric yield ratios of fission products in the system of 24 MeV proton-induced fission of238U

Abstract

Abstract. Isomeric yield ratios of 30 fission products in 24 MeV proton-induced fission of 23au were measured by the use of the ion-guide isotope separator on-line. The obtained isomeric yield ratios were converted to the angular momenta of primary fission fragments based on the statistical model. The deduced angular momenta were examined from various aspects. It is found that in general the angular momentum continuously increases with the fragment mass number including the region of symmetric mass division. However, there are some exceptions. For Sn isotopes the deduced angular momenta are quite small due to the spherical shape of the nuclear shell configuration. It is also concluded from the consideration of the charge distribution that the angular momentum of fission product scatters considerably within the narrow range of mass division. The dependence of the angular momentum on the available energy of fragments at scission point indicates that the individual fragment possesses a characteristic deformation at scission and/or the deduced angular momentum is seriously affected by the particle excitation after scission.

Measurements of isomeric yield ratios of fission products from proton-induced fission onnatU and232Th via direct ion counting

“…Nevertheless, the comparison between IYRs from different fissioning system should be done cautiously, as explained earlier, due to the different decay paths in the de-excitation of the fission fragments. The ratios of the present work from both targets agree reasonably with the measurement in [9].…”

“…The only existing comparable data set in the literature is also included in the table [9]. The uncertainties include only the statistical ones, and thus they are underestimated.…”

Measurement of Isomeric Yield Ratios of Fission Products With the Jyfltrap

“…A very similar experiment utilizing the IGISOL method and γ-spectroscopy technique was done by M. Tanikawa et al [3]. Data analysis is in progress and comparison between two different methods and literature values will be performed in future.…”

“…They include isotope separator [3], recoil mass separator [4] or radiochemical methods in combination with γ-ray spectroscopy. The bottleneck all of this methods is the detection of isomeric and ground states by their decays.…”

First isomeric yield ratio measurements by direct ion counting and implications for the angular momentum of the primary fission fragments

“…In case the isomeric yield ratios are measured by means of γ spectroscopy, as reported in Refs. [48][49][50], the fission fragments can be transported and detected within milliseconds. For ion counting with JYFLTRAP, as in the present study, the ions are detected within a few hundreds of ms from their creation.…”