Search for β-delayed fission of 178Aug,m and an updated systematics in the region of neutron-deficient nuclei

Abstract

A search for a β-delayed fission (βDF) decay branch of isomerically pure samples of 178Aug and 178Aum was performed at the ISOLDE-CERN facility. Two complementary detection systems capable of registering α decays and fission fragments, the ISOLDE Decay Station and the ASET (Alpha SETup), were used. Despite very high statistics of produced 178Au nuclei, no fission fragments were detected. Upper limits of βDF probabilities of PβDF(178Aug) < 1.11(2) × 10−8 and PβDF(178Aum) < 9.7(2) × 10−9 were determined. Corresponding lower limits of βDF partial half-lives were deduced as well, and the results are discussed in the context of experimental systematics of βDF in the neutron-deficient region of the nuclear chart.