Studies of the two-step scheme for new RI-beam production in the medium-heavy very-neutron-rich region
ORAL · Invited
Abstract
Two studies about the “two-step scheme” performed at BigRIPS in RI Beam Factory will be presented.
The first one is an investigation of usefulness of the two-step scheme [1], which was proposed [2] for an efficient production of medium-heavy very-neutron-rich radioactive isotopes (RI) as an alternative method to the in-flight fission of 238U (one-step scheme). The one-step scheme is expected to be limited soon: Production cross sections for the very neutron-rich RIs have been drastically decrease with neutron numbers (N). The two-step method may produce more exotic RIs by the following two steps: In the first step, a long-lived neutron-rich RI (e.g. 132Sn) is produced by ISOL and post-accelerated, then, more exotic RI (e.g. 128Pd) is produced by fragmentation in the second step. To evaluate its usefulness, we have measured the cross sections of very neutron-rich Pd isotopes produced from a 132Sn beam and compared their estimated yields by the two- and one-step schemes under an assumption of 1-MW beam facilities. This comparison suggests that the two-step scheme with 132Sn provides yields >40-times higher than those by the one-step scheme for very neutron-rich N = 82 region. Moreover, we examined which scheme is better to produce RIs at each region in the nuclear chart by using various long-lived RI beams supplied from ISOL in the two-step scheme.
The other one is about a new RI-beam production/separation method in BigRIPS, “in-separator two-step method” [3], which could have an advantage for obtaining yields of very neutron-rich RIs compared to the in-flight fission of 238U. In the proposed new method, less-exotic intermediate RI is produced in the 1st stage and more-exotic objective RI is produced and separated in the 2nd stage. The experimental results with 133Sn as the intermediate RI will be shown.
References
[1] H. Suzuki et al., Phys. Rev. C 102 (2020) 064615.
[2] K. Helariutta et al., Eur. Phys. J. A 17 (2003) 181.
[3] H. Suzuki et al., RIKEN Acc. Prog. Rep. 55 (2021) S7.
The first one is an investigation of usefulness of the two-step scheme [1], which was proposed [2] for an efficient production of medium-heavy very-neutron-rich radioactive isotopes (RI) as an alternative method to the in-flight fission of 238U (one-step scheme). The one-step scheme is expected to be limited soon: Production cross sections for the very neutron-rich RIs have been drastically decrease with neutron numbers (N). The two-step method may produce more exotic RIs by the following two steps: In the first step, a long-lived neutron-rich RI (e.g. 132Sn) is produced by ISOL and post-accelerated, then, more exotic RI (e.g. 128Pd) is produced by fragmentation in the second step. To evaluate its usefulness, we have measured the cross sections of very neutron-rich Pd isotopes produced from a 132Sn beam and compared their estimated yields by the two- and one-step schemes under an assumption of 1-MW beam facilities. This comparison suggests that the two-step scheme with 132Sn provides yields >40-times higher than those by the one-step scheme for very neutron-rich N = 82 region. Moreover, we examined which scheme is better to produce RIs at each region in the nuclear chart by using various long-lived RI beams supplied from ISOL in the two-step scheme.
The other one is about a new RI-beam production/separation method in BigRIPS, “in-separator two-step method” [3], which could have an advantage for obtaining yields of very neutron-rich RIs compared to the in-flight fission of 238U. In the proposed new method, less-exotic intermediate RI is produced in the 1st stage and more-exotic objective RI is produced and separated in the 2nd stage. The experimental results with 133Sn as the intermediate RI will be shown.
References
[1] H. Suzuki et al., Phys. Rev. C 102 (2020) 064615.
[2] K. Helariutta et al., Eur. Phys. J. A 17 (2003) 181.
[3] H. Suzuki et al., RIKEN Acc. Prog. Rep. 55 (2021) S7.
–
Presenters
-
Hiroshi Suzuki
RIKEN Nishina Center, RIKEN
Authors
-
Hiroshi Suzuki
RIKEN Nishina Center, RIKEN
-
Naoki Fukuda
RIKEN Nishina Center, RIKEN
-
Hiroyuki Takeda
RIKEN Nishina Center, RIKEN
-
Yohei Shimizu
RIKEN Nishina Center, RIKEN
-
Deuksoon Ahn
Center for Exotic Nuclear Studies, IBS, RIKEN Nishina Center, Center for Exotic Nuclear Study IBS
-
Toshiyuki Sumikama
RIKEN Nishina Center
-
Masahiro Yoshimoto
RIKEN Nishina Center
-
Koichi Yoshida
RIKEN Nishina Center, RIKEN
-
Toshiyuki Kubo
RIKEN Nishina Center
-
Walter F Henning
Argonne National Laboratory, Technische Universitaet Muenchen