Transport efficiency of JAERI recoil mass separator

Solid angles and transport efficiencies of the JAERI recoil mass separator were measured by using three procedures, that is, by using (1) α-particles from an 241Am source, (2) elastic recoils of 197Au produced in the bombardments of 28Si beams on 197Au targets and (3) evaporation residues produced in the fusion reaction of 30Si+ 141Pr. The solid angles of 11 and 21 msr were obtained for the focus conditions of the mass dispersion (x | δm)=−1.1 and 0 cm/% respectively. The measured transport efficiency was compared with the ion-optical calculation of GIOS and a good agreement between the calculation and the present data was obtained. The charge state distributions of low-energy heavy recoils 167Ta and 197Au were also measured and compared with the various calculations. It was found that the empirical formula by Shima et al. well reproduced the present data.