Magnetic moments of the2+first excited states of even iron isotopes

Abstract

The large magnetic fields that act on fast-moving ions traversing thin magnetized Fe foils were utilized to remeasure the magnetic moments of the first excited 2+ states of "Fe and ' Fe. The technique reported here does not require an accurate knowledge of the nuclear lifetime and does not depend on the static magnetic field of Fe in Fe. Assuming g(~~Fe, 2+) = 0.61 + 0.08, we obtain g = 1.68~0.38 and g = 0.46+ 0.10 for the first 2+ states of "Fe and Fe, respectively. The present results agree well with previous measurements and support the existing models for the structure of these states.

The shell model and collective structures in54,55,56Fe

“…With a threehole model space and a Kallio-Kolltveit interaction Zamick [24] obtained for the magnetic moment of the 2+ state the value #= +2.97 n.m. Averaging the two most recent experimental values [29,30] one finds g= +2.4+_0.3 n.m., which is in excellent agreement with the present three-hole values. The lifetimes of the 4+ and 6[ states calculated in the three-hole space differ quite strongly between KB and SDI.…”

gfactor of the first excited state inFe56and implications for transient-field calibration in the Fe region

“…The value of g(2 + 1 ) for 56 Fe that has been commonly adopted for the past two decades [7][8][9] is an average of three earlier studies: two by radioactivity techniques [11,12] and one by the "thick-foil" transient-field implantation perturbed angular correlation (IMPAC) technique [13]. In this section, we argue that the latter measurement should be discarded.…”

“…Since this IMPAC g-factor result for 56 Fe includes the radioactivity data, it is not valid to then combine it (again) in an average with the same radioactivity data, as has been done to obtain the g(2 + 1 ) value adopted for the past couple of decades [7][8][9].…”

“…The reference point for transient-field calibrations in this region [3][4][5][6] is the g factor of the first-excited state in 56 Fe, for which g = +0.61 ± 0.08 has been adopted for the past two decades [7][8][9]. Unfortunately, as will be shown below, the uncertainty in this value is underestimated: the correct average value based on previously published data should be g(2 + 1 ; 56 Fe) = +0.61 ± 0.13, having an experimental uncertainty of ∼±21%.…”

Relativeg-factor measurements inFe54,East1, Stuchbery2, Chamoli3 et al. 2009Phys. Rev. C

“…Although stable, 58 Fe has an abundance of only 0.28%, and is not readily produced as a sufficiently intense beam from a natural iron sample by the ion sources in typical tandem laboratories. The previously reported g factors, measured by the transient field in conventional kinematics [5], and by integral perturbed angular correlations in radioactivity [6], have uncertainties of the order of 30%.…”