Recoil-distance measurements of g-factors for 24Mg(21+) and 20Ne(21+)

Time-differential recoil-into-vacuum measurements have been performed with a plunger on the first-excited I^π = 2⁺ states of ²⁴Mg and ²⁰Ne. The states were populated by the reactions ¹²C(¹⁶O, α)²⁴Mg and ¹²C(¹²C, α)²⁰Ne. The measured anisotropy of the α-γ angular correlation was greatly increased by means of a vertical slit on the annular particle detector. Values of $\text{¦g¦= 0.51 ± 0.02}\text{and}\text{0.54 ± 0.04}$ have been deduced for the ²⁴Mg and ²⁰Ne g-factors, respectively. The mean lives of these states have been determined as τ_m = 2.09 ± 0.13 ps and 0.8 ± 0.2 ps, respectively. Various theoretical calculations are discussed and compared with the measured g-factors.The analysis of the measurement also yields values for the populations of electronic states contributing to the hyperfine interaction. For ²⁰Ne the populations of the different electronic configurations are compared with the results of a separate time-integral measurement, in which the correlations were measured for each ionic state separately. Large fractions of two-electron excited states are found to contribute.