The decay characteristic of ${}^{22}$Si and its ground-state mass significantly affected by three-nucleon forces

Abstract

The decay of the proton-rich nucleus ${}^{22}$Si was studied by a silicon array coupled with germanium clover detectors. Nine charged-particle groups are observed and most of them are recognized as ${\hat{I}}^2$-delayed proton emission. A charged-particle group at 5600 keV is identified experimentally as ${\hat{I}}^2$-delayed two-proton emission from the isobaric analog state of ${}^{22}$Al. Another charged-particle emission without any ${\hat{I}}^2$ particle at the low energy less than 300 keV is observed. The half-life of ${}^{22}$Si is determined as 27.5 (18) ms. The experimental results of ${\hat{I}}^2$-decay of ${}^{22}$Si are compared and in nice agreement with shell-model calculations. The mass excess of the ground state of ${}^{22}$Si deduced from the experimental data shows that three-nucleon (3N) forces with repulsive contributions have significant effects on nuclei near the proton drip line.

6 pages, 4 figures