Schmidt Value Research Articles

On the suppression of magnetic octupole moments

Some recent experiments have indicated that there is a large suppression of M3 moments, relative to the single-particle estimates, in a number of light nuclei. We calculate the correction to the M3 Schmidt value up to second order in perturbation theory in the case of a closed f 7 2 shell plus a neutron employing realistic effective interactions. The overall second-order corrections are found to be quite significant from the point of view of explaining the large observed deviations. It turns out that, whereas the renormalization terms yield a sizeable contribution which adds coherently to the first-order corrections, the “dequenching” arising from Tamm-Dancoff type graphs is quite small.

Magnetic moment of 57Ni

In a recent experimental study, the magnetic moment of the ground state of 57Ni has been measured to be equal to | μ| = 0.88 ± 0.06 μ N, which is only about 45 per cent of the Schmidt value. The significant departure from the Schmidt value is explained in a microscopic, parameter-free manner employing the improved effective interactions in the 2p-1f shell. Quite contrary to the results obtained in a number of recent calculations, it turns out that the observed magnetic moment for 57Ni ground state is not inconsistent with the zeroth-order description of the 56Ni 0848 ground state in terms of an inert f 7 2 core.

Magnetic Moment of the6+Isomeric State ofTe134

The inherent alignment of the prompt fission fragments was used to measure the g factor of the 6/sup +/ isomeric state of /sup 134/Te by the time-differential perturbed angular-correlation method. The experimental result, g/sub exp/ = 0.846 +- 0.25, is close to effective g factors of g/sub 7/2/ protons in nuclei with 82 neutrons. The deviation from the Schmidt value is discussed in terms of the polarization of the 132/sub 50/Sn/sub 82/ core by the g/sub 7/2/ protons. (AIP)

Magnetic moment of 57Ni

An extra neutron added to a doubly magic nuclear core should give a nuclear magnetic moment, μ, in close agreement with the Schmidt value. However, the magnetic moment of 57Ni, measured through nuclear alignment at 3–20 mK, is equal to ∣ μ∣ = 0.88±0.06 μ N which is only 45% of the Schmidt value. Comparison with several nuclear structure calculations is made.

Magnetic moment and deformed component in 41Ca and 39K

It is found that the inclusion of deformed core-excited states in the wave functions for 41Ca and 39K produces important corrections to the magnetic moments. The discrepancies between observed magnetic moments and theoretical predictions are considerably reduced in both cases. The deformed components also account for a large part of the experimentally found reduction of the Gamow-Teller matrix element in β-decay. It is pointed out that the fact that high spatial symmetry seems to be favoured in the 16O region may provide an explanation of the small reduction of the Schmidt value in 17O.

Magnetic Moments of the7−and5−(πh92,νg92) States inBi210

The $g$ factors of the 433-keV ${7}^{\ensuremath{-}}$ state and the 439-keV ${5}^{\ensuremath{-}}$ state in $^{210}\mathrm{Bi}$ which are predominantly ($\ensuremath{\pi}{h}_{\frac{9}{2}}$, $\ensuremath{\nu}{g}_{\frac{9}{2}}$) have been measured as $g({7}^{\ensuremath{-}})=0.302\ifmmode\pm\else\textpm\fi{}0.007$ and $g({5}^{\ensuremath{-}})=0.306\ifmmode\pm\else\textpm\fi{}0.009$ by a time-differential method using the reaction $^{208}\mathrm{Pb}(^{7}\mathrm{Li},\ensuremath{\alpha}n)^{210}\mathrm{Bi}$. From these experimental results, a magnetic moment for the ${g}_{\frac{9}{2}}$ neutron of $\ensuremath{\mu}=\ensuremath{-}(1.33\ifmmode\pm\else\textpm\fi{}0.06){\ensuremath{\mu}}_{N}$ [$g(\ensuremath{\nu}{g}_{\frac{9}{2}})=\ensuremath{-}0.296\ifmmode\pm\else\textpm\fi{}0.014$] has been deduced. This ${g}_{\frac{9}{2}}$-neutron magnetic moment is in agreement with the Schmidt value corrected for core polarization.

A Mössbauer observation of the magnetic moment of the 89 keV excited state of 119Sn

The magnetic moment of the 89 keV excited state of 119Sn has been determined from Mössbauer measurements made below 100 mK. The value obtained was − 1.40±0.08 μ N. Its deviation from the Schmidt value − 1.91 μ N is consistent with systematics and nuclear theory estimates.

Anomalous Orbital Magnetism of Proton Deduced from the Magnetic Moment of the11−State ofPo210

It is well known that the magnetic moment of the h9/2 state in 209Bi deviates largely from the Schmidt value. Theoretical calculations based on the magnetic core polarization mechanism1,2) could account for only half of its deviation and the remainder has been left as a question.

The nuclear magnetic moment of indium-117m

The hyperfine structure of 1.9-hour 117mIn has been investigated using atomic magnetic resonance. In the 2P1/2 and 2P3/2 electronic states, the magnetic dipole interaction constants are[Formula: see text]If the possibility of a hyperfine anomaly is neglected, the nuclear magnetic moment of 117mIn is −0.251 46 ± 0.000 03 nuclear magnetons. Thus the nucleus follows the trend shown by other 2p1/2 proton nuclei, namely that the addition of a neutron pair always reduces the deviation from the Schmidt value.

The magnetic moment of the 5 − state of 116Sn and other spectroscopic investigations in the decay of 116Sb and 116In

The g-factor of the 5 − state of 116Sn at 2369 keV has been measured by observing the rotation of the 545–1073 keV γγ angular correlation in external magnetic fields. The result g = − 0.065 ± 0.005 agrees well with the Schmidt value for the pure, two-neutron, shell-model configuration (h 11/2, s 1/2) 5−; it disagrees, however, with recent theoretical predictions which postulate rather strong admixtures of the (h 11/2, d 3/2) 5− configuration. We observed an additional level of 116Sn at 3215 keV. It is directly populated by EC and β +-decays of 116Sb. It decays by a γ-transition of 846 keV to the 5 − state or by a γ-transition of 438 keV to the 6 − state. The 438 keV line fits only into the decay scheme if the 136 keV line sits on top of the 410 keV line. The order of these last two lines was uncertain previously. The half-life of the 5 − state at 2369 keV was redetermined as T 1 2 = ( 3.5 ± 2.0 ) ⋅ 10 − 7 S . This value is larger than previously reported. For the half-lives of the 2914 and the 3215 keV states, we found T 1 2 ≤ 5 ⋅ 10 − 10 S . The γγ angular correlation measurements on eight different cascades in the decay of 116Sb confirmed the spin and multipolarity assignments of previous investigations. We assign the spin 7 − to the new level at 3215 keV. The small ft value of the β-decay which populates the new state excludes smaller spins and the opposite parity; the high transition rates of the following γ-decays exclude higher spins.

The nuclear magnetic moment of copper

The doublet hyperfine structures of the resonance lines of the copper arc spectrum, λ3247 and λ3274, have been measured with a quartz Lummer plate. The lines are produced free from reversal effects, the doublet separations being respectively 379 and 405 × 10-3 cm-1. The following hyperfine structure interval factors are calculated: 3d104s2S½ = 197.5, 3d104p2P½ = 14 and 3d104p2P1½ = 4.8 (all in cm-1 × 10-3). The mean nuclear magnetic moment for the two copper isotopes, 63 and 65, is derived from the ground state, 3d104s2S½. The value found is μ = 2.47 nuclear magnetons, this being probably a better estimate than that given by other terms, since the ground state is spherically symmetrical and thus not affected by quadrupole moment of the nucleus. By adopting Schüler and Schmidt's value for the ratio of the magnetic moments of the two isotopes, it is found that μ (63Cu) = 2.43 and μ (65Cu) = 2.54 nuclear magnetons.