Relative $g$-factor measurements in ${}^{54}\mathrm{Fe}$, ${}^{56}\mathrm{Fe}$, and ${}^{58}\mathrm{Fe}$

The $g$ factors of the $2_1^{+}$ states in ${}^{54}\mathrm{Fe}$ and ${}^{58}\mathrm{Fe}$ have been measured relative to the $2_1^{+}$ state $g$ factor of ${}^{56}\mathrm{Fe}$ using the transient-field technique in inverse kinematics. The results are in satisfactory agreement with recent shell model calculations in the $\mathit{fp}$ model space. For ${}^{56}\mathrm{Fe}$ and ${}^{58}\mathrm{Fe}$ the $g$ factors approach $Z/A$ and are therefore also consistent with collective interpretations of these $2^{+}$ states.

Figure 1

Spectra observed by $\gamma$-ray detectors at $+{65}^{°}$ (Ge detector: left panels) and $+{115}^{°}$ (NaI detector: right panels) in coincidence with the central particle detector. These spectra show the data for magnetic field ‘up’ collected over a period of $~8$ h for ${}^{56}\mathrm{Fe}$ and $~32$ h for ${}^{54}\mathrm{Fe}$ and ${}^{58}\mathrm{Fe}$. The Doppler broadened line shape of the 1408 keV transition is clearly seen in the lower left panel.

Figure 2

Fit to the Doppler broadened line shape of the 1408 keV transition in ${}^{54}\mathrm{Fe}$ as observed in the detector at $+{65}^{°}$ to the beam, in coincidence with C ions recorded in the central particle detector. Data for field ‘up’ and ‘down’ have been added. The extracted lifetime for the $2^{+}$ level agrees with that reported by Speidel et al. [7].

Figure 3

Upper panel: $R_{42}$ ratios for the isotopes ${}^{54,56,58}\mathrm{Fe}$. Lower panel: Comparison of experimental $2_1^{+}$ level $g$ factors with $\mathit{fp}$ shell model calculations [1]. The dashed line indicates the collective model estimate, $g=Z/A$.