$\beta^{+}$ Gamow-Teller strengths from unstable $^{14}$O via the $(d,{}^2\text{He})$ reaction in inverse kinematics

TL;DR

This study successfully used inverse kinematics with a novel detection setup to measure Gamow-Teller strengths from unstable $^{14}$O, providing insights into nuclear structure and testing advanced theoretical models.

Contribution

First application of the $(d,{}^2 ext{He})$ reaction in inverse kinematics to extract $eta^{+}$ Gamow-Teller strengths from an unstable nucleus, combined with comparison to modern theoretical calculations.

Findings

Shell-model reproduces strength up to 15 MeV with quenching.

Coupled-cluster calculations match full strength distribution without quenching.

Results support the use of advanced models for understanding Gamow-Teller quenching.

Abstract

For the first time, the $(d,{}^2\text{He})$ reaction was successfully used in inverse kinematics to extract the Gamow-Teller transition strength in the $\beta^{+}$ direction from an unstable nucleus. The nucleus studied was $^{14}$O, and the Gamow-Teller transition strength to $^{14}$N was extracted up to an excitation energy of 22 MeV. The measurement of the $(d,{}^2\text{He})$ reaction in inverse kinematics was made possible by the combination of an active target time projection chamber and a magnetic spectrometer. The data were used to test shell-model and state-of-the-art coupled cluster calculations. Shell-model calculations reproduce the measured Gamow-Teller strength distribution up to about 15 MeV reasonably well, after the application of a phenomenological quenching factor. Coupled-cluster calculation reproduces the full strength distribution well without such quenching, owing to the large model space, the inclusion of strong correlations, and the coupling of the weak interaction to two nucleons through two-body currents. This indicates that such calculations provide a very promising path for answering long-standing questions about the observed quenching of Gamow-Teller strengths in nuclei.