Short-lived excited-state $g$ factors of fast $^{38,40}$S fragments*

The transient field technique for measuring short-lived excited-state magnetic dipole moments generally requires ion velocities comparable to $Zv_0$ ($v_0$ = $c$/137) or lower, which, at face value, would preclude the study of the wide range of isotopes available at fragmentation facilities. However, stringent testing of nuclear models far from stability can be realized with $g$-factor measurements of these isotopes, once the experimental challenges are overcome. Measurements performed at the NSCL's Coupled Cyclotron Facility have extended the transient field technique to radionuclides produced as in-flight fast fragments. The high velocity transient field technique was applied to intermediate-energy beams of $^{38}$S and $^{40}$S. The signs of their first-excited 2$^+$ state $g$ factors were obtained, and with a parametrization of the transient field strength at high velocities, the $g$-factor magnitudes were extracted. Results, experimental details, and future outlook will be presented.