First-excited state g factor of Te136 by the recoil in vacuum method

Electromagnetic properties of atomic nuclei such as $E2$ transition rates and $M1$ magnetic moments (or $g$ factors) are crucial characteristics of structure. For unstable nuclei produced as reaccelerated radioactive beams, measurements of $g$ factors present numerous challenges. This paper develops the important recoil-in-vacuum technique to obtain a $g$ factor for the ${2}^{+}$ state in ${}^{136}$Te. The result fits existing systematics but also highlights anomalous values in other $N=84$ isotones, thus presenting an important challenge to theory in the region just above doubly magic ${}^{132}$Sn.