Speaker
Description
We have promoted fission measurement using multinucleon transfer (MNT) reactions. The reaction allows us to study fission of many nuclei, including neutron-rich nuclei, which cannot be populated by other reactions [1]. Also, excitation energy ($E^{*}$) of compound nucleus distributes widely, which can be used to investigate excitation-energy dependence of fission. The experiments were carried out at the JAEA tandem accelerator facility using 18O beam and various radioactive target nuclei ($^{232}$Th, $^{238}$U, $^{237}$Np, $^{243}$Am, $^{248}$Cm) [2,3]. It was demonstrated that data fission-fragment mass distributions (FFMDs) for more than 20 nuclides were obtained in one reaction, and their excitation energy dependence up to $E^{*}$=60 MeV was derived. The measured FFMDs were explained by taking into account the multi-chance fission, i.e. fission after neutron emission [4,5]. From the threshold of the excitation function of fission probably, fission barrier height was derived [6].
Our setup for MNT-induced fission allows us to obtain data for MNT mechanism itself. From the fission-fragment angular distribution relative to the rotational axis of the fissioning nucleus, we determined the average angular momentum for each MNT channel [7]. This measurement is useful for the surrogate reaction study, where effects of different spin distribution of compound nucleus between transfer and neutron-induced reaction needs to be properly taken into account.
Reference
[1] K. Nishio, “Multinucleon-Transfer-Induced Fission”, Handbook of Nuclear Physics, Springer, pp 901-943 (2023).
[2] R. Leguillon et al., Phys. Lett. B 761, 125 (2016).
[3] M.J. Vermeulen et al., Phys. Rev. C 102, 054610 (2020).
[4] K. Hirose et al., Phys. Rev. Lett. 119, 222501 (2017).
[5] S. Tanaka et al., Phys. Rev. C 100, 064605 (2019).
[6] K.R. Kean et al., 100, 014611 (2019).
[7] S. Tanaka et al., Phys. Rev. C 105, L021602 (2022).
Keywords : Fission, Multinucleon transfer reaction, Multichance fission
