Electric quadrupole transition probabilities for singly ionized magnesium

Electric quadrupole transition probabilities for Mg II have been calculated within the weakest bound electron potential model (WBEPM) theory using experimental energy levels and theoretical expectation values of orbital radii corresponding to those energy levels under the assumption of the LS coupling scheme. In this work, the WBEPM theory has been applied to forbidden transitions for the first time. The present results are consistent with earlier theoretical calculations. Some of these results are reported for the first time.     

Electric quadrupole moments of neutron-rich nuclei 32Al and 31Al

The electric quadrupole moments for the ground states of ³²Al and ³¹Al have been measured by the β ray-detected nuclear quadrupole resonance method. Spin-polarized ³²Al and ³¹Al nuclei were obtained from the fragmentation of ⁴⁰Ar projectiles at E/A?=?95 MeV/nucleon, and were implanted in a single crystal α-Al₂O₃ stopper. The measured Q moment of ³²Al, |Q(³²Al)|?=?24(2) mb, is in good agreement with a conventional shell-model calculation with a full sd model space and empirical effective charges, while that of ³¹Al is considerably smaller than the sd calculations.     

Static electric quadrupole and hexadecapole moments of nuclei

Ground-state static electric quadrupole and hexadecapole moments of even nuclei are calculated microscopically. Rare-earth, actinide and neutron-deficient nuclei with 50 <Z, N < 82 and neutron-rich nuclei with 28 < Z < 50, 50 < N < 82 are studied. Fairly good agreement with experiment is found. In the actinide region, the electric moments of fission isomers are also examined.     

Current electric quadrupole moments of atoms and nuclei

It is shown that current electric multipoles exist. Their field is electrostatic and it is unrelated to the existence of a net electric charge. At long range, it is the same as the field of the corresponding charge electric multipoles. Current electric multipoles arise during the motion of magnetic multipoles. An orbital motion of magnetic dipoles, a precession of a current-carrying loop, and the motion of magnetic quadrupoles all lead to current electric quadrupole moments. Expressions for the current electric quadrupole moments of atoms and nuclei are derived.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 7, pp. 53–58, July, 1991.The author wishes to thank S. A. Kuten' and V. I. Rapoport for useful comments offered during the writing of this paper and for a discussion of the results.     

Electric quadrupole and magnetic octupole moments of the light decuplet baryons within light cone QCD sum rules

The electric quadrupole and magnetic octupole moments of the light decuplet baryons are calculated in the framework of the light cone QCD sum rules. The obtained non-vanishing values for the electric quadrupole and magnetic octupole moments of these baryons show nonspherical charge distribution. The sign of electric quadrupole moment is positive for Ω⁻, Ξ^*−, Σ^*− and negative for Σ^*+, which correspond to the prolate and oblate charge distributions, respectively. A comparison of the obtained results with the predictions of non-covariant quark model which shows a good consistency between two approaches is also presented. Comparison of the obtained results on the multipole moments of the decuplet baryons containing strange quark with those of Δ baryons shows a large SU(3) flavor symmetry breaking.     

Microscopic quadrupole and hexadecapole moments of rare earth nuclei

The theoretical calculations of multipole moments of even-even rare earth nuclei are presented. The potential energy surface is evaluated by the shell correction method. The condition ensuring the equality of the density distribution of the macroscopic liquid droplet part of the potential energy and the density generated by the single particle potential is added. A single particle Nilsson potential is used. New, less stiff potential surfaces versusε ₄ are obtained while the multipole moments calculated at the equilibrium deformations agree well with experimental data.     

Shape transition in light Pt isotopes: Magnetic moments and electric quadrupole moment ratios for185,187,189Pt

Nuclear orientation and nuclear magnetic resonance experiments were performed on^{185, 187, 189}Pt isotopes oriented in Fe and single crystal Zn at temperatures down to about 6 mK. The hyperfine splitting frequencies of¹⁸⁵Pt and¹⁸⁷Pt in iron were determined to be 164.9(2) and 261.1(2) MHz, respectively. With the hyperfine field of −126.1(2.5) T, the g-factors are deduced to be |g(¹⁸⁵Pt)|=0.172(3) and |g(¹⁸⁷Pt)|=0.272(5). The spectroscopic quadrupole moment of¹⁸⁷Pt was found to be negative with magnitude similar to that of¹⁸⁹Pt, indicating a predominantly oblate ground state deformation for both isotopes. The spectroscopic quadrupole moment of¹⁸⁵Pt was found to be positive, with the ratio Q(¹⁸⁵Pt)/Q(¹⁸⁹Pt)=−3.6(9), clearly indicating a change to prolate ground state deformation.     

Transition probabilities and static moments of excited states in even-even nuclei

A new approach is made to calculate the generalized single-particle density matrixp ^μv in even-even nuclei. It is shown that this quantity is included in the three particle response function, for which we derived a renormalized equation. Taking into account in a consequent way the effective particle-hole interaction we received a formula for the static moment of excited states and the transition probability between such states which is essentially different from the usual RPA theory.     

Parity- and time-reversal-violating moments of light nuclei

I present the calculation of parity- and time-reversal-violating moments of the nucleon and light nuclei, originating from the QCD $\bar \theta$ term and effective dimension-six operators. By applying chiral effective field theory these calculations are performed in a unified framework. I argue that measurements of a few light-nuclear electric dipole moments would shed light on the mechanism of parity and time-reversal violation.     

Electric quadrupole moments of the D states of alkaline-earth-metal ions

The electric quadrupole moment for the 4d(2)D(5/2) state of (88)Sr(+); one of the most important candidates for an optical clock, has been calculated using the relativistic coupled-cluster theory. This is the first application of this theory to determine atomic electric quadrupole moments. The result of the calculation is presented and the important many-body contributions are highlighted. The calculated electric quadrupole moment is (2.94 +/- 0.07)ea(2)(0), where a(o) is the Bohr radius and the electronic charge while the measured value is (2.6 +/- 0.3) ea(2)(0). This is so far the most accurate determination of the electric quadrupole moment for the above mentioned state. We have also calculated the electric quadrupole moments for the metastable 4d(2)D(3/2) state of 88(Sr(+) and for the 3d(2)D(3/2.5/2) and 5d(2)D(3/2.5/2) states of (43)Ca(+) and (138)Ba(+), respectively.     

Theoretical studies of electric quadrupole transition probabilities in Mg II

The relativistic coupled cluster theory is employed to calculate electric quadrupole (E2) transition probabilities among the doublet states of Mg II which are of interest in astrophysical problems. This is the first time a highly correlated fully ab initio method has been used to compute these quantities for this particular ion. The line strengths and transition probabilities of a number of different transitions are reported and compared with those available in the literature.Received: 4 June 2003, Published online: 30 September 2003PACS: 31.10. + z Theory of electronic structure, electronic transitions, and chemical bindingSonjoy Majumder: Present address: Institut für Theoretische Chemie, Technische Universität München, 85747 Garching, Germany.     

Spectra of multiquantum echo signals from quadrupole nuclei with half-integral spin in magnetically ordered materials

The numerical simulation of two-pulse echo signals at times 2τ, 4τ, and 6τ for the I=5/2 spin and at time 2τ, 4τ, and 8τ for the I=7/2 spin (τ is the time interval between exciting pulses) is carried out. It is shown that a delay by 2τ in the moment of formation of the echo results in the disappearance of extreme quadrupole satellites in the NMR spectrum obtained by recording the frequency dependence of the echo amplitude. The echoes at the maximum possible time of formation (2I+1)τ are only observed at the frequency of the purely magnetic spectroscopic transition $ \pm \frac{1}{2} \rightleftarrows \mp \frac{1}{2}$ ; no such echoes are observed at the quadrupole satellite frequencies. The computations are compared with the experimental results obtained for the ⁵⁵Mn nuclei (spin I=5/2) in the perovskite GdCu₃Mn₄O₁₂ and the spinel Li_0.5Fe_2.5O₄: Mn.     

Pulsed nuclear quadrupole double-resonance scheme for the detection of rare quadrupolar nuclei

A scheme for transient pure quadrupole double resonance in the rotating frame, involving off resonant irradiation of the abundant quadrupolar spins, has been proposed for the detection of rare quadrupolar nuclei. The applicability of the method has been demonstrated by a presentation of the recorded ²³Na pure quadrupole double-resonance spectrum of a polycrystalline specimen of sodium chlorate. In contrast to the other double-resonance schemes in the pure quadrupole regime, the present scheme reduces spectrometer requirements in terms of transmitter power and hardware.     

Search for the Jacobi shape transition in light nuclei

The -rays following the reaction 105 MeV ¹⁸O + ²⁸Si have been measured using the EUROBALL IV, HECTOR and EUCLIDES arrays in order to investigate the predicted Jacobi shape transition. The high-energy -ray spectrum from the GDR decay indicates the presence of large deformations in the hot ⁴⁶Ti nucleus, in agreement with new theoretical calculations based on the rotating liquid-drop model.Received: 29 November 2002, Published online: 9 March 2004PACS: 24.30.Cz Giant Resonances - 21.60.Ev Collective modelsJ.P. Vivien: Deceased     

Microscopic treatment of the coupled monopole and quadrupole vibrations in light nuclei

The coupled monopole and volume-conserving quadrupole oscillations in ⁴He, ¹²C, ¹⁶O, ²⁰Ne and ⁴⁰Ca have been studied within the framework of the Hill-Wheeler generator coordinate method.     

Magnetic and quadrupole moments of light spin-1 mesons in light cone QCD sum rules

The magnetic and quadrupole moments of the light-vector and axial-vector mesons are calculated in the light cone QCD sum rules. Our results for the static properties of these mesons are compared with the predictions of lattice QCD as well as other approaches existing in the literature.     

Measurement of electric quadrupole moments of neutron-rich nuclei14B and15B

The experimental study of nuclear moments of several neutron-rich nuclei, using the phenomenon of ejectile spin polarization in the projectile fragmentation reaction, is reported. The spin-polarized fragments¹⁴B and¹⁵B were produced in the fragmentation of¹⁸O projectiles on a Nb target at 64.7 MeV/u. They were implanted into a Mg single crystal, and the quadrupole momentsQ were determined by the-NMR method. The results, ¦Q(¹⁴B)¦ =29.84 ±0.75 mb and ¦Q(¹⁵B)¦=38.01 ±1.08 mb, are compared with theoretical models. Shell model calculations in a 0 model space, using effective charges commonly accepted in this mass region, predict values about 40% larger than the experimentalQ(¹⁵B). Agreement is obtained when a much smaller effective charge for neutrons is employed. The method was also applied to the measurement of the magnetic moments of¹⁷N and¹⁷B. The result reveals an important contribution of configurations with excess neutrons coupled to formJ =2⁺.