Magnetic moments of the low-lying JP = 1/2-, 3/2- Λ resonances within the framework of the chiral quark model
A. Martinez Torres et al
The magnetic moments of the low-lying spin-parity JP = 1/2-, 3/2- Λ resonances, like, for example, Λ(1405)1/2-, Λ(1520) 3/2-, as well as their transition magnetic moments, are calculated using the chiral quark model. The results found are compared with those obtained from the nonrelativistic quark model and those of unitary chiral theories, where some of these states are generated through the dynamics of two hadron coupled channels and their unitarization.
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December 11th, 2012 in
Hyperfine structure anomaly and magnetic moments of neutron deficient Tl isomers with I=9/2
A.E. Barzakh et al.
The hyperfine structure of 276.9-nm atomic transition has been studied by the resonant ionization spectroscopy method at mass-separator IRIS (Investigation of Radioactive Isotopes on Synchrocyclotron), Petersburg Nuclear Physics Institute (PNPI) for the odd Tl isomers with I=9/2 and A=187–197. A differential hyperfine structure anomaly for 6p2P1/2 and 7s2S1/2 atomic states in Tl isomers with I=9/2 has been determined. It is described by the recently developed theoretical approach fairly well. This enables one to recalculate the magnetic moments of 187−193Tlm(I=9/2) from previously measured hyperfine splittings for 7s2S1/2 states and to determine for the first time the magnetic moments for 197Tlm and 195Tlm(I=9/2) from hyperfine splittings for 6p2P1/2 states with properly taking into account the rather great hyperfine structure anomaly. Similar measurements with greater accuracy have been proposed for the other nuclear states in odd-odd Tl isotopes. These measurements could shed light on the nuclear magnetization distribution in these isotopes.
July 18th, 2012 in
, g factor
| tags: 187Tl
, magnetic moment
, resonant ionization spectroscopy
Magnetic moments of K isomers as indicators of octupole collectivity
N. Minkov and P. M. Walker
The relation between the quadrupole-octupole deformation and the structure of high-K isomers in heavy even-even nuclei is studied through a reflection asymmetric deformed shell model including a BCS procedure with constant pairing interaction. Two-quasiparticle states with Kπ=4−, 5−, 6−, 6+ and 7− are considered in the region of actinide nuclei (U, Pu and Cm) and rare-earth nuclei (Nd, Sm and Gd). The behaviour of two-quasiparticle energies and magnetic dipole moments of these configurations is examined over a wide range in the plane of quadrupole and octupole deformations (&betal2 and β3. In all considered actinide nuclei, the calculations show that there is pronounced sensitivity of the magnetic moments to the octupole deformation. In the rare-earth nuclei, the calculations for 154,156Gd show stronger sensitivity of the magnetic moment to the octupole deformation than in the other considered cases.
Spectroscopy on a single trapped 137Ba+ ion for nuclear magnetic octupole moment determination
N.C. Lewty et al.
We present precision measurements of the hyperfine splittings in the 5D3/2 manifold of a single trapped Barium ion, 137Ba+. Measurements of the hyperfine splittings are made between mF = 0 sublevels over a range of magnetic fields allowing us to interpolate to the zero field splittings with an accuracy below 10 Hz. Our results, in conjunction with theoretical calculations, allow the determination of the hyperfine coupling constant, C, with an accuracy below 0.1 Hz. This gives a subsequent determination of the nuclear magnetic octupole moment with an uncertainty limited almost completely by the accuracy of theoretical calculations.
Self-consistent calculations of quadrupole moments of the first 2+ states in Sn and Pb isotopes
D. Voitenkov et al.
A method of describing static moments of excited states and transitions between excited states is formulated for nonmagic nuclei within the Green’s function formalism. Quadrupole moments of the first 2+ states in tin and lead isotope chains are calculated self-consistently using the energy density functional by Fayans et al. [Nucl. Phys. A 676 49 (2000)]. Reasonable agreement with available experimental data is obtained. Quadrupole moments of unstable nuclei including 100Sn and 132Sn are predicted. A nontrivial dependence of the quadrupole moments on the neutron excess is found which can be traced to the negative proton contributions.
Observation of 239Pu Nuclear Magnetic Resonance
H. Yasuoka et al.
In principle, the spin-½ plutonium-239 (239Pu) nucleus should be active in nuclear magnetic resonance spectroscopy. However, its signal has eluded detection for the past 50 years. Here, we report observation of a 239Pu resonance from a solid sample of plutonium dioxide (PuO2) subjected to a wide scan of external magnetic field values (3 to 8 tesla) at a temperature of 4 kelvin. By mapping the external field dependence of the measured resonance frequency, we determined the nuclear gyromagnetic ratio 239γγn(PuO2)/2π to be 2.856&plusm;0.001 megahertz per tesla (MHz/T). Assuming a free-ion value for the Pu4+ hyperfine coupling constant, we estimated a bare 239γγn/2π value of ~2.29 MHz/T, corresponding to a nuclear magnetic moment of μn ≈ 0.15 μμN (where μN is the nuclear magneton).
Quadrupole moments of spherical semi-magic nuclei within the self-consistent Theory of Finite Fermi Systems
S.V. Tolokonnikov et al.
The quadrupole moments of odd neighbors of semi-magic lead and tin isotopes and N=50, N=82 isotones are calculated within the self-consistent Theory of Finite Fermi Systems based on the Energy Density Functional by Fayans et al. Two sets of published functionals are used to estimate systematic errors of the present self-consistent approach. They differ by the spin-orbit and effective tensor force parameters. The functional DF3-a leads to quadrupole moments in reasonable agreement with the experimental ones for most, but not all, nuclei considered.
Structure of the Sr-Zr isotopes near and at the magic N=50 shell from g-factor and lifetime measurements in8840Zr and 84,86,8838Sr
G. Kumbartzki et al.
Background: The evolution of and interplay between single-particle and collective excitations in the 40 ⩽N⩽ 50 range for 38Sr and 40Zr isotopes have been studied.
Purpose: Measurement of the g factor of the 21+ and 41+ states in radioactive 88Zr while simultaneously remeasuring the g(21+) factors in the Sr isotopes and extention of the measurements to higher energy states in the Sr isotopes. Lifetimes of states in these nuclei are determined.
Methods: The transient field technique in inverse kinematics and line-shape analysis using the Doppler-shift attenuation method are applied. The 88Zr nuclei were produced by the transfer of an α particle from the 12C nuclei of the target to 84Sr nuclei in the beam. The excited states in the stable 84Sr isotopes were simultaneously populated via Coulomb excitation by 12C in the same target. Coulomb excitation measurements on 86,88Sr were carried out with the same apparatus.
Results: The resulting g factors and B(E2) values of these nuclei reveal similarities between the two chains of Zr and Sr isotopes. Large-scale shell-model calculations were performed within the p3/2, f5/2, p1/2, g9/2 orbital space for both protons and neutrons and yielded results in agreement with the experimental data.
Conclusions: In this paper the magnetic moments and lifetimes of several low-lying states in 88Zr and 84,86,88Sr have been measured and compared to large-scale shell-model calculations.
April 30th, 2012 in
, g factor
| tags: 84Sr
, g factor
, shell model
Is the 7/21- Isomer State of 43S Spherical?
R. Chevrier et al.
We report on the spectroscopic quadrupole moment measurement of the 7/21- isomeric state in 4316S27 [E*=320.5(5) keV, T1/2=415(3) ns], using the time dependent perturbed angular distribution technique at the RIKEN RIBF facility. Our value, ∣Qs∣=23(3) efm2, is larger than that expected for a single-particle state. Shell model calculations using the modern SDPF-U interaction for this mass region reproduce remarkably well the measured ∣Qs∣, and show that non-negligible correlations drive the isomeric state away from a purely spherical shape.