Allowed electron-capture branches in the decay of 34mCl

Abstract

The decay of 34mCl has been studied with 36 and 100 cm 3 Ge(Li) detectors and with a high-resolution large volume Ge(Li)-NaI(Tl) Compton-suppression spectrometer. The 34mCl activity was produced with the reaction 24Mg( 12C, pn) 34Cl at E( 12 C) = 35 MeV by bombarding thick natural Mg targets. The half-life was measured to be τ 1 2 = 32.06 ± 0.08 min . Nine γ-ray transitions were observed including four γ-rays not seen previously. The measured γ-ray intensities determine new electron-capture branches of (0.030 ± 0.006) % and (0.032 ± 0.003) % to 34S levels at 4.69 and 4.88 MeV with log ft values of 5.48 ± 0.08 and 5.26 ±0.04, respectively. These log ft values imply allowed transitions and are consistent with the known J π values of J π = 4 + and 3 + of the 4.69 and 4.88 MeV levels, respectively. A lower limit of log ft ⪢ 6.9 is obtained for the allowed electron-capture branch to the J π = 2 +, 4.89 MeV level. Other previously observed decay branches have been confirmed. Since the decay of 34mCl proceeds (46.9 ± 1.0)% to the 34Cl ground state, the latter decay was studied concurrently; 34Cl(0)with J π = 0 +, T = 1 decays exclusively to its analog 34S(0) and the sum of the intensities of four other allowed branches is less than 1.2 × 10 −4 of the intensity of the ground-state branch. The experimental results are compared with recent shell-model calculations performed in a large configuration space.