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Theo
[paper] Erosion of N=20 shell in 33Al investigated through the ground-state electric quadrupole moment
Erosion of N=20 shell in 33Al investigated through the ground-state electric quadrupole moment
K. Shimada et al.
doi: 10.1016/j.physletb.2012.07.030
Electric quadrupole moment Q of the ground state has been measured by means of β-NMR spectroscopy using a spin-polarized beam produced in a projectile fragmentation reaction. The obtained Q moment, |Qexp(33Al)|=132(16) emb, shows a significant excess from the prediction of shell model calculations within the sd shell. The result indicates sizable admixing of pf intruder configurations in the ground state, demonstrating that the N=20 shell closure certainly erodes in 33Al, a nucleus located on the border of the island of inversion. Comparison was made with predictions of the Monte Carlo shell model, and also a particle-vibration coupling model treating the neutron pairing correlations in the ground state of 33Al. Again, a significant admixture of pf intruder configurations to the ground state was needed in both theoretical approaches to explain the observed large Q.
[paper] Hyperfine structure anomaly and magnetic moments of neutron deficient Tl isomers with I=9/2
Hyperfine structure anomaly and magnetic moments of neutron deficient Tl isomers with I=9/2
A.E. Barzakh et al.
doi: 10.1103/PhysRevC.86.014311
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.
[paper] Deuteron magnetic quadrupole moment from chiral effective field theory
Deuteron magnetic quadrupole moment from chiral effective field theory
C.-P. Liu et al.
doi: 10.1016/j.physletb.2012.06.024
We calculate the magnetic quadrupole moment (MQM) of the deuteron at leading order in the systematic expansion provided by chiral effective field theory. We take into account parity (P) and time-reversal (T) violation which, at the quark–gluon level, results from the QCD vacuum angle and dimension-six operators that originate from physics beyond the Standard Model. We show that the deuteron MQM can be expressed in terms of five low-energy constants that appear in the P- and T-violating nuclear potential and electromagnetic current, four of which also contribute to the electric dipole moments of light nuclei. We conclude that the deuteron MQM has an enhanced sensitivity to the QCD vacuum angle and that its measurement would be complementary to the proposed measurements of light-nuclear EDMs.
[paper] Magnetic moments of K isomers as indicators of octupole collectivity
Magnetic moments of K isomers as indicators of octupole collectivity
N. Minkov and P. M. Walker
doi: 10.1140/epja/i2012-12080-y
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.
[preprint] Spectroscopy on a single trapped 137Ba+ ion for nuclear magnetic octupole moment determination
Spectroscopy on a single trapped 137Ba+ ion for nuclear magnetic octupole moment determination
N.C. Lewty et al.
arXiv: http://arxiv.org/abs/1205.6908
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.
[paper] Self-consistent calculations of quadrupole moments of the first 2+ states in Sn and Pb isotopes
Self-consistent calculations of quadrupole moments of the first 2+ states in Sn and Pb isotopes
D. Voitenkov et al.
doi: 10.1103/PhysRevC.85.054319
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.
[paper] Observation of 239Pu Nuclear Magnetic Resonance
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).
[paper] Quadrupole moments of spherical semi-magic nuclei within the self-consistent Theory of Finite Fermi Systems
Quadrupole moments of spherical semi-magic nuclei within the self-consistent Theory of Finite Fermi Systems
S.V. Tolokonnikov et al.
doi: 10.1140/epja/i2012-12070-1
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.
[paper] 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
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.
doi: 10.1103/PhysRevC.85.044322
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.