Reaction studies for the synthesis of heavy nuclei

Heavy-ion reaction studies at the JAEA tandem accelerator facility will be discussed. In order to predict cross sections to produce super-heavy nuclei in fusion-evaporation reactions, it is essential to determine fusion probability, i.e. the probability to produce compound nucleus after a system overcome and/or penetrate the Coulomb barrier. Our attempt to determine fusion probability from the measurement of fission fragments mass distributions and evaporation residue cross sections will be presented, particularly placing emphasis on the effects of static deformation of the target nucleus ²³⁸U on fusion, using various projectile nuclei ¹⁶O - ⁴⁸Ca [1-4].

Recently, we are promoting a program of reaction studies in multi-nucleon transfer (MNT) reactions using various actinide target nuclei [5,6]. The MNT reaction allows us to produce neutron-rich nuclei, which cannot be populated by particle capture/fusion reactions. The MNT reactions are also used to measure fission properties and fission barrier heights for various nuclei. From the data, competition between neutron-emission and fission is discussed [7].

Reference

[1] K. Nishio et al., Phys. Rev. Lett. 93, 162701 (2004).

[2] K. Nishio et al., Phys. Rev. C 77, 064607 (2008).

[3] K. Nishio et al., Phys. Rev. C 82, 024611 (2010), Phys. Rev. C 82, 044604 (2010).

[4] K. Nishio et al., Phys. Rev. C 86, 034608 (2012).

[5] R. Léguillon et al., Phys. Lett. B 761, 125 (2016).

[6] A.N. Andreyev, K. Nishio, K.-H. Schmidt, Rep. Prog. Phys. 81, 016301 (2018).

[7] K. Hirose et al., Phys. Rev. Lett. 119, 222501 (2017).