The properties of a nanosecond isomer in 32Si, disputed in previous studies, depend on the evolution of proton and neutron shell gaps near the `island of inversion'. We have placed the isomer at 5505.2(2) keV with Jπ=5−, decaying primarily via an E3 transition to the 21+ state. The E3 strength of 0.0841(10) W.u. is unusually small and suggests that this isomer is dominated by the (νd3/2)−1⊗(νf7/2)1 configuration, which is sensitive to the N=20 shell gap. A newly observed 41+ state is placed at 5881.4(13) keV; its energy is enhanced by the Z=14 subshell closure. This indicates that the isomer is located in a `yrast trap', a feature rarely seen at low mass numbers.
@article{arxiv.2311.09163,
title = {Identifying the spin trapped character of the $^{32}$Si isomeric state},
author = {J. Williams and G. Hackman and K. Starosta and R. S. Lubna and Priyanka Choudhary and P. C. Srivastava and C. Andreoiu and D. Annen and H. Asch and M. D. H. K. G. Badanage and G. C. Ball and M. Beuschlein and H. Bidaman and V. Bildstein and R. Coleman and A. B. Garnsworthy and B. Greaves and G. Leckenby and V. Karayonchev and M. S. Martin and C. Natzke and C. M. Petrache and A. Radich and E. Raleigh-Smith and D. Rhodes and R. Russell and M. Satrazani and P. Spagnoletti and C. E. Svensson and D. Tam and F. Wu and D. Yates and Z. Yu},
journal= {arXiv preprint arXiv:2311.09163},
year = {2023}
}