Beta decay of the MT=-1 nucleus 58Zn studied by selective laser ionization

Abstract

IS353 collaboration AbstractBeta decay of 58 Zn has been studied for the first time. A new laser ion-source concept has been used to produce mass-separated sources for beta and gamma spectroscopy. The half-life of 58 Zn was determined to be 86 (18)

First identification of ⁵⁸Zn <em>β</em>-delayed proton emission

“…The resulting branching ratio for β p emission was calculated to be 0.7(1)%. This value is compatible with the upper limit of 3% given by Jokinen et al [9]. Among the 88 protons observed, 55 escaped the chamber and could not be considered further in the analysis.…”

First identification of Zn58 β -delayed proton emission

“…The resulting branching ratio for β p emission was calculated to be 0.7(1)%. This value is compatible with the upper limit of 3% given by Jokinen et al [9]. The gray histogram shows the raw PMT signal, while the black curve is the same signal processed through a median filter.…”

“…β p emission is therefore expected and its observation would provide data on higher-lying GT strength distribution with respect to previous β-decay measurements. This would be important information complementary to that provided by CE reactions, since in such studies background subtraction is particularly delicate, as concluded by Jokinen et al in their work [9].…”

“…Later measurements confirmed the half-life with improved accuracy [86(2) ms] and the nonobservation of β p emission [10]. The decay of 58 Zn proceeds via a superallowed Fermi transition to the 0 + first excited state in 58 Cu (IAS), at only 203 keV excitation energy, and via GT transitions to the ground state and to the 1 + state at 1.052 keV [9,10]. Figure 1 shows the partial decay scheme of 58 Zn in which all data published to date is reported.…”

“…Direct identification and mass measurement of 58 Zn were performed with the pion double-charge exchange reaction 58 Ni(π + , π − ) 58 Zn [8]. The β decay of 58 Zn was studied for the first time with the ISOL technique with selective laser ionization and its half-life was determined to be 86(18) ms. At the same time an upper limit for β p emission was set to 3% [9]. Later measurements confirmed the half-life with improved accuracy [86(2) ms] and the nonobservation of β p emission [10].…”