Excitation function for the production of ²⁶⁵108 and ²⁶⁶109

Abstract

The excitation function for the production of²⁶⁶109 by the reaction ⁵⁸Fe + ²⁰⁹Bi was investigated. Its position and width could be reproduced using the same values (E* = 13.9 MeV; FWHM=4.8 MeV) as inthe case of²⁶⁵108 produced by the reaction ⁵⁸Fe + ²⁰⁸Pb. A cross-section maximum of (7.5 ± 2.7) pb was obtained. Referred to ²⁶⁵108, this value is reduced by a factor of 8.8 ± 3.3, that is more than the average reduction of cross-section by 3.7 per element. The hindrance factor of 2.4 ± 0.9 could be due to a specialization energy in the fusion process by the unpaired proton of ²⁰⁹Bi in the h_9/2 orbital. A total of twelve decay chains of ²⁶⁶109 was measured, resulting in a mean half-life of ( ^+0.6_1.7−0.4 ) ms. The new data confirm the decay data of the previously measured two decays of ²⁶⁶109.