The evidence of $N=16$ shell closure and ${\hat{I}}^2$-delayed neutron emission from ${}^{25}$F

Abstract

We measured the ${\hat{I}}^2$-delayed neutron emission from ${}^{25}$F for the first time at the Facility for Rare Isotope Beams (FRIB). Using combined neutron and ${\hat{I}}^3$-ray detector systems of the FRIB Decay Station Initiator (FDSi), we observed ${\hat{I}}^2$-decay transitions populating neutron unbound states between 4.2 and 8 MeV in ${}^{25}$Ne. The experimental results led to the revision of the ${\hat{I}}^2$-decay half-life and ${\hat{I}}^2$-delayed neutron-emission probability of ${}^{25}$F. The ${\hat{I}}^2$-decay strength distribution of ${}^{25}$F extracted from the data agrees with the shell-model predictions using the USDB and SDPF-M effective interactions. This result indicates that the spherical neutron $N=16$ shell gap persists in ${}^{25}$F and ${}^{25}$Ne.

7 pages