Production cross section measurements of radioactive isotopes by BigRIPS separator at RIKEN RI Beam Factory

摘要

We have measured the production rates and production cross sections for avariety of radioactive isotopes which were produced from 124Xe, 48Ca, and 238Ubeams at an energy of 345 MeV/nucleon using the BigRIPS separator at the RIKENNishina Center RI Beam Factory (RIBF). Proton-rich isotopes with atomic numbersZ = 40 to 52 and neutron-rich isotopes with Z = 5 to 16 were produced byprojectile fragmentation of the 124Xe and 48Ca beam on Be targets,respectively. Neutron-rich isotopes with Z = 20 to 59 were produced byin-flight fission of the 238U beam, in which both Be and Pb were used asproduction targets. The measured production rates and production cross sectionswere compared with those of the LISE++ calculations, and overall fairly goodagreement has been obtained. Furthermore, in the measurements with the 124Xebeam, we have discovered four new isotopes on the proton-drip line, 85,86Ru and81,82Mo, and obtained the clear evidence that 103Sb is particle unbound with anupper limit of 49 ns for the half-life. The measurements of projectile-fragmentmomentum distributions have been also performed with the 124Xe beam, in whichthe low-momentum tails of the distributions have been measured for the firsttime at the energy of 345 MeV/nucleon.