Neutron-rich radioactive isotope (RI) beams in the vicinity of Zr110 were produced using the in-flight fission of a 345-MeV/nucleon U238 beam at the RIKEN Radioactive Isotope Beam Factory. The RI beams were separated in flight by the large-acceptance two-stage fragment separator BigRIPS. Isotopes were clearly identified in a low-background particle-identification plot, which was obtained from the measurements of time of flight, magnetic rigidity, and energy loss using beam-line detectors placed in the BigRIPS separator and the ZeroDegree spectrometer. Nine new isotopes, Br101, Kr102, Rb105,106, Sr108, Y110,111, Zr114, and Nb117, are reported for the first time, with their measured production cross sections compared with the extrapolations of lighter isotopes down to the femtobarn regime.
Bibliographical noteFunding Information:
This experiment was carried out at the RIBF operated by the RIKEN Nishina Center, and the Center for Nuclear Study, the University of Tokyo. The authors acknowledge the RIBF accelerator staffs for their efforts in delivering an intense beam. This work was supported by JSPS KAKENHI Grants No. 2301752, No. 24740188, No. 25247045, No. 26800117, and No. 16K17680, NRF Grant No. 2016K1A3A7A09005575, STFC Grants No. ST/J000132/1, No. ST/J000051/1, No. ST/K502431/1, No. ST/L005743/1, No. ST/P003885/1, No. ST/P003982/1, and No. ST/P005314/1, DOE Grant No. DE-FG02-91ER-40609, BMBF Grant No. 05P19RDFN1, and Spanish Ministerio de Ciencia e Innovación under Contracts No. FPA2009-13377-C02 and No. FPA2011-29854-C04. P.H.R. and G.L. acknowledge additional support from the UK Department for Business, Energy and Industrial Strategy (BEIS) via funding for the UK National Measurement System. P.-A.S. was financed by the RIKEN Foreign Postdoctoral Researcher Program.