g-factor measurements at RISING: The cases of 127Sn and 128Sn
L. Atanasova et al
doi: 10.1209/0295-5075/91/42001
We report on g-factor measurements of the 19/2+ T1/2=4.5(3) μs isomer in 127Sn and the 10+ T1/2=2.69(23) μs isomer in 128Sn. These isomers were produced and spin-aligned in relativistic heavy-ion fragmentation at GSI and were selected and separated by the GSI fragment separator (FRS). The γ-rays of the isomeric decay were detected by the RISING γ-ray spectrometer. The method of time-differential perturbed angular distributions was utilized. The measured g-factors, g(19/2+; 127Sn)=-0.17(2) and g(10+; 128Sn)=-0.20(4), are compared with shell model calculations. The measured g-factors confirm the predominantly νh11/2-2and ν(s1/2-1h11/2-2) character of the 10+ and 19/2- isomers in 128Sn and 127Sn, respectively. The results demonstrate the feasibility of the method for similar measurements in exotic neutron-rich nuclei.
Effect of spin-orbit nuclear charge density corrections due to the anomalous magnetic moment on halo nuclei
A. Ong et al.
doi: 10.1103/PhysRevC.82.014320
In this paper we consider the contribution of the anomalous magnetic moments of protons and neutrons to the nuclear charge density. We show that the spin-orbit contribution to the mean-square charge radius, which has been neglected in recent nuclear calculations, can be important in light halo nuclei. We estimate the size of the effect in helium, lithium, and beryllium nuclei. It is found that the spin-orbit contribution represents a ~2% correction to the charge density at the center of the 7Be nucleus. We derive a simple expression for the correction to the mean-square charge radius due to the spin-orbit term and find that in light halo nuclei it may be larger than the Darwin-Foldy term and comparable to finite size corrections. A comparison of experimental and theoretical mean-square radii including the spin-orbit contribution is presented.
Description of magnetic moments of long isotopic chains within the FFS theory
I.N. Borzov et al.
doi: 10.1140/epja/i2010-10985-y
Dipole magnetic moments of several long isotopic chains are analyzed within the self-consistent finite Fermi system theory with exact account for the pairing and quasiparticle continuum. The momentum dependence of the spin-isospin Landau-Migdal amplitude g’ is taken into account. This dependence was introduced previously to describe high-energy electron magnetic scattering. New moment data for nuclei far from the β-stability valley are included in the analysis. For a number of semi-magic isotopes of the tin and lead chains a good description of the data is obtained, with an accuracy of 0.1-0.2μN. A chain of non-magic isotopes of copper is also analyzed in detail.
Nuclear Spins and Moments of Ga Isotopes Reveal Sudden Structural Changes between N=40 and N=50
B. Cheal et al.
doi: 10.1103/PhysRevLett.104.252502
Collinear laser spectroscopy was performed on Ga (Z=31) isotopes at ISOLDE, CERN. A gas-filled linear Paul trap (ISCOOL) was used to extend measurements towards very neutron-rich isotopes (N=36–50). A ground state (g.s.) spin I=1/2 is measured for 73Ga, being near degenerate with a 3/2- isomer (75 eV≤Eex≤1 keV). The 79Ga g.s., with I=3/2, is dominated by protons in the πf5/2 orbital and in 81Ga the 5/2- level becomes the g.s. The data are compared to shell-model calculations in the f5/2pg9/2 model space, calling for further theoretical developments and new experiments.
July 21st, 2010 in
gfac.pubs | tags:
69Ga,
71Ga,
73Ga,
75Ga,
77Ga,
79Ga,
81Ga,
ISOLDE,
Laser spectroscopy,
magnetic moments,
Paul trap,
quadrupole moment,
shell model calculations |
No Comments
Ratio of Isoscalar to Isovector Core Polarization for Magnetic Moments
L.Zamick, Y.Y.Sharon, S.J.Q. Robinson
url: 1006.4856
In calculations of isoscalar magnetic moments of odd-odd N=Z nuclei it was found that for medium to heavy mass nuclei large scale shell model calculations yielded results which were very close to much simpler single j shell ones. To understand this we compare isoscalar and isovector configuration mixing in first order perturbation theory using a spin dependant delata interaction.The isoscalar corrections are much smaller
Magnetic moment of 104Agm and the hyperfine magnetic field of Ag in Fe using nuclear magnetic resonance on oriented nuclei
V.V. Golovko et al.
url: 1006.5885
Nuclear magnetic resonance (NMR/ON) measurements with beta- and gamma-ray detection have been performed on oriented Ag-104(g,m) nuclei with the NICOLE He-3-He-4 dilution refrigerator setup at ISOLDE/CERN. For Ag-104(m) (I-pi = 5(+)) the gamma-NMR/ON resonance signal was found at nu = 266.70(5) MHz. Combining this result with the known magnetic moment for this isotope, the magnetic hyperfine field of Ag impurities in an Fe host at low temperature (< 1 K) is found to be |B-hf(AgFe)| = 44.709(35) T. A detailed analysis of other relevant data available in the literature yields three more values for this hyperfine field. Averaging all four values yields a new and precise value for the hyperfine field of Ag in Fe; that is, |B-hf(AgFe)| = 44.692(30) T. For Ag-104(m) (I-pi = 2(+)), the anisotropy of the beta particles provided the NMR/ON resonance signal at ν = 627.7(4) MHz. Using the new value for the hyperfine field of Ag in Fe, this frequency corresponds to the magnetic moment μ(Ag-104m) = +3.691(3) μ(N), which is significantly more precise than previous results. The magnetic moments of the even-A Ag102-110 isotopes are discussed in view of the competition between the (π g(9/2))(7/2+)(-3)(ν d(5/2) ν g(7/2))(5/2+) and the (π g(9/2))(9/2+)(-3)(ν d(5/2)ν g(7/2))(5/2+) configurations. The magnetic moments of the ground and isomeric states of Ag-104 can be explained by an almost complete mixing of these two configurations.
Spin-alignment and g-factor measurement of the Iπ = 12+ isomer in 192Pb produced in the relativistic-energy fragmentation of a 238U beam
M. Kmiecik et al.
doi: 10.1140/epja/i2010-11003-4
The feasibility of measuring g-factors using the TDPAD method applied to high-energy, heavy fragmentation products is explored. The 2623keV Iπ=12+ isomer in 192Pb with τ=1.57 μs has been produced using the fragmentation of a 1A GeV 238U beam. The results presented demonstrate for the first time that such heavy nuclei produced in a fragmentation reaction with a relativistic beam are sufficiently well spin-aligned. Moreover, the rather large value of the alignment, 28(10)% of the maximum possible, is preserved during the separation process allowing the determination of magnetic moments. The measured values of the lifetime, τ=1.54(9) μs, and the g-factor, g=-0.175(20), agree with the results of previous investigations using fusion-evaporation reactions.
July 9th, 2010 in
gfac.pubs | tags:
192Pb,
238U,
EPJA,
FRS,
g factor,
gRISING,
GSI,
isomer,
paper,
TDPAD |
No Comments
New measurement of the 68Zn(41+) g factor combined with a reanalysis of previous data
K. Moschner, K.-H. Speidel, J. Leske, C. Bauer, C. Bernards, L. Bettermann, M. Honma4, T. Möller, P. Maier-Komor, and D. Mücher
doi: 10.1103/PhysRevC.82.014301
We have remeasured and have redetermined the g factor for the 41+ state in 68Zn following inconsistencies between earlier measurements and a recent result. We have reanalyzed several former measurements by applying an alternative analysis procedure, which allows for determining the precession effect separately for each gamma detector implying less uncertainties in the background subtraction for the relevant spectra. In addition, all measured g-factor and B(E2) data for the first 2+ and 4+ states in all stable even-A Zn isotopes and the radioactive 62Zn, are compared with new large-scale shell model calculations based on the most advanced effective interaction in the fpg-shell model space.
A model for right-handed neutrino magnetic moments
A. Aparici et al.
doi: 10.1088/0954-3899/37/7/075012
A simple extension of the standard model providing Majorana magnetic moments to right-handed neutrinos is presented. The model contains, in addition to the standard model particles and right-handed neutrinos, just a singly charged scalar and a vector-like charged fermion. The phenomenology of the model is analysed and its implications in cosmology, astrophysics and lepton flavour violating processes are extracted. If light enough, the charged particles responsible for the right-handed neutrino magnetic moments could copiously be produced at the Large Hadron Collider.
Magnetic dipole moment of the light tensor mesons in light cone QCD sum rules
T.M. Aliev, K. Azizi and M. Savci
doi: 10.1088/0954-3899/37/7/075008
The magnetic dipole moments of the light tensor mesons f2, a2 and the strange K*02(1430) tensor meson are calculated in the framework of the light cone QCD sum rules. It is observed that the values of the magnetic dipole moment for the charged tensor particles are considerably different from zero. These values are very close to zero for the light neutral f2 and a2 tensor mesons, while it has a small nonzero value for the neutral strange K*02(1430) tensor meson.