First β− -decay spectroscopy study of Nd157

As part of an effort to better understand the structure of neutron-rich, rare-earth nuclei that are involved in the $r$ process, an experiment aimed at the ${\ensuremath{\beta}}^{\ensuremath{-}}$-decay spectroscopy of $^{157}\mathrm{Nd}$ was performed. The CARIBU source provided an isobarically separated $A=157$ beam which was delivered to the SATURN decay station at Argonne National Laboratory. A half-life of ${t}_{1/2}=1.17(4)$ s was measured for the $^{157}\mathrm{Nd}$ decay, which is in agreement with a previously reported value. A level scheme based on the $^{157}\mathrm{Nd}\phantom{\rule{4pt}{0ex}}{\ensuremath{\beta}}^{\ensuremath{-}}$ decay was established for the first time. The level at 1703 keV in the daughter $^{157}\mathrm{Pm}$ nucleus was assigned the $\ensuremath{\pi}7/2[523]$ configuration and it was found to be populated quite strongly as a result of an allowed-unhindered ``spin-flip'' transition from the $\ensuremath{\nu}5/2[523]$ ground state in $^{157}\mathrm{Nd}$.