Reliability test for the experimental results of electric-quadrupole hyperfine-structure constants and assessment of nuclear quadrupole moments in 135Ba and <... (original) (raw)
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Reexamination of nuclear quadrupole moments in ^{39−41}K isotopes
Physical Review A, 2012
Nuclear quadrupole moments (Qs) in three isotopes of potassium (K) with atomic mass numbers 39, 40 and 41 are evaluated more precisely in this work. The Q value of 39 K is determined to be 0.0614(6) b by combining the available experimental result of the electric quadrupole hyperfine structure constant (B) with our calculated B/Q result of its 4P 3/2 state. Furthermore combining this Q value with the measured ratios Q(40 K)/Q(39 K) and Q(41 K)/Q(39 K), we obtain Q(40 K)= −0.0764(10) b and Q(41 K)= 0.0747(10) b, respectively. These results disagree with the recently quoted standard values in the nuclear data table within the given uncertainties. The calculations are carried out by employing the relativistic coupled-cluster theory at the singles, doubles and involving important valence triples approximation. The accuracies of the calculated B/Q results can be viewed on the basis of comparison between our calculated magnetic dipole hyperfine structure constants (As) with their corresponding measurements for many low-lying states. Both A and B results in few more excited states are presented for the first time.
The nuclear quadrupole moments of 191,193,195,197Pb and 139La
The intermediate Hamiltonian coupled cluster method is applied to calculate the nuclear quadrupole moments (NQM) of Pb and La. Large, converged basis sets are used to get the electric field gradients at the relevant nuclei; these make possible the extraction of the NQM from the measured hyperfine coupling constant B. The only Pb NQM listed in Pyykkö's 2008 table (Mol Phys 106:1965) is for the neutron-rich unstable 209 isotope (halflife 3.25 h), given as -269 mb. This error bound of 60%, the largest in the table, comes from the poor precision of the measured B. More precise B values are now available for the neutron-poor isotopes with atomic weights 191, 193, 195, 197 and their NQMs are calculated herein. The best values obtained for these four isotopes are, respectively, 78(11), 179(9), 281(12), and 347(15) mb. The electric field gradient at the nucleus is the same for all Pb isotopes, so that NQMs of other isotopes may be evaluated when better B values become available for them. The same method is applied to 139 La, for which an accurate B value in the b 1 D 2 state has recently become available. The calculated NQM is 206(4) mb, in excellent agreement with the recent molecular value of 200(6) mb.
New determination of the Nuclear Quadrupole Moments of In isotopes
We present here a new determination of the quadrupole moment Q of hyperfine-probe-nuclei states of three different In isotopes: the 5+ 192 keV excited state of 114In (probe for Nuclear Orientation experiments), the 9/2+ ground state of 115In (Nuclear Magnetic and Nuclear Quadrupole Resonance probe) and the 3/2+ 659 keV excited state of 117In (Perturbed-Angular-Correlations probe). These nuclear quadrupole values were determined by comparing experimental nuclear-quadrupole frequencies with the electric-field-gradient tensor (EFG) calculated at In sites in metallic Indium within the Density-Functional Theory. These accurate ab initio calculations were performed with the WIEN97.10 implemenattion of the Full-Potential Linearized-Augmented Plane-Wave method. The obtained results for the quadrupole moments [Q(114In) = -0.14(1) b; Q(115In) = -0.77(1) b; Q(117In) = 0.59(1) b] are in clear discrepancy with those reported in the literature [Q(114In) = +0.14(6) b; Q(115In) = +0.861(45) b; Q(11...
Nuclear quadrupole moment of 197Au from high-accuracy atomic calculations
The Journal of Chemical Physics, 2007
The electric field gradient (EFG) at the gold nucleus is calculated using a finite field approach, to make the extraction of the nuclear quadrupole moment Q from experimental nuclear quadrupole coupling constants possible. The four-component Dirac-Coulomb Hamiltonian serves as the framework, 51 of the 79 electrons are correlated by the relativistic Fock-space coupled cluster method with single and double excitations, and the contribution of the Gaunt term, the main part of the Breit interaction, is evaluated. Large basis sets (up to 26s22p18d12f8g5h uncontracted Gaussians) are employed. Energy splittings of the D5/22 and D3/22 levels, rather than level shifts, are used to extract the EFG constants, as the former remain linear with Q up to 10-5a.u., whereas the latter display significant nonlinearity even at Q =10-8a.u. Larger Q values lead to larger energy changes and better precision. Excellent agreement (0.1%) is obtained between Q values derived from D5/22 and D3/22 data. Systematic errors connected with neglecting triple and higher excitations, truncating the basis and orbital active space, and approximating the Gaunt contribution are evaluated. The final value of Q(Au197) is 521(7)mb. It is lower than the muonic 547(16)mb and agrees within error bounds with the recent value of 510(15)mb obtained from molecular calculations.
Precision calculation of hyperfine constants for extracting nuclear moments of 229Th
Determination of nuclear moments for many nuclei relies on the computation of hyperfine constants, with theoretical uncertainties directly affecting the resulting uncertainties of the nuclear moments. In this work we improve the precision of such method by including for the first time an iterative solution of equations for the core triple cluster amplitudes into the relativistic coupledcluster method, with large-scale complete basis sets. We carried out calculations of the energies and magnetic dipole and electric quadrupole hyperfine structure constants for the low-lying states of 229 Th 3+ in the framework of such relativistic coupled-cluster single double triple (CCSDT) method. We present a detailed study of various corrections to all calculated properties. Using the theory results and experimental data we found the nuclear magnetic dipole and electric quadrupole moments to be µ = 0.366(6)µN and Q = 3.11(2) eb, and reducing the uncertainty of the quadrupole moment by a factor of three. The Bohr-Weisskopf effect of the finite nuclear magnetization is investigated, with bounds placed on the deviation of the magnetization distribution from the uniform one.
Nuclear quadrupole moment of [sup 197]Au from high-accuracy atomic calculations
The Journal of Chemical Physics, 2007
The electric field gradient ͑EFG͒ at the gold nucleus is calculated using a finite field approach, to make the extraction of the nuclear quadrupole moment Q from experimental nuclear quadrupole coupling constants possible. The four-component Dirac-Coulomb Hamiltonian serves as the framework, 51 of the 79 electrons are correlated by the relativistic Fock-space coupled cluster method with single and double excitations, and the contribution of the Gaunt term, the main part of the Breit interaction, is evaluated. Large basis sets ͑up to 26s22p18d12f8g5h uncontracted Gaussians͒ are employed. Energy splittings of the 2 D 5/2 and 2 D 3/2 levels, rather than level shifts, are used to extract the EFG constants, as the former remain linear with Q up to 10 −5 a.u., whereas the latter display significant nonlinearity even at Q =10 −8 a.u. Larger Q values lead to larger energy changes and better precision. Excellent agreement ͑0.1%͒ is obtained between Q values derived from 2 D 5/2 and 2 D 3/2 data. Systematic errors connected with neglecting triple and higher excitations, truncating the basis and orbital active space, and approximating the Gaunt contribution are evaluated. The final value of Q͑ 197 Au͒ is 521͑7͒ mb. It is lower than the muonic 547͑16͒ mb and agrees within error bounds with the recent value of 510͑15͒ mb obtained from molecular calculations.
The electric quadrupole moments for some scandium isotopes (41, 43, 44, 45, 46, 47 Sc) have been calculated using the shell model in the proton-neutron formalism. Excitations out of major shell model space were taken into account through a microscopic theory which is called core polarization effectives. The set of effective charges adopted in the theoretical calculations emerging about the core polarization effect. NushellX@MSU code was used to calculate one body density matrix (OBDM). The simple harmonic oscillator potential has been used to generate the single particle matrix elements. Our theoretical calculations for the quadrupole moments used the two types of effective interactions to obtain the best interaction compared with the experimental data. The theoretical results of the quadrupole moments for some scandium isotopes performed with FPD6 interaction and Bohr-Mottelson effective charge agree with experimental values.
Electric quadrupole moments of the21+states inCd100,102,104
Physical Review C, 2009
Using the REX-ISOLDE facility at CERN the Coulomb excitation cross sections for the 0 + gs → 2 + 1 transition in the β-unstable isotopes 100,102,104 Cd have been measured for the first time. Two different targets were used, which allows for the first extraction of the static electric quadrupole moments Q(2 + 1) in 102,104 Cd. In addition to the B(E2) values in 102,104 Cd, a first experimental limit for the B(E2) value in 100 Cd is presented. The data was analyzed using the maximum likelihood method. The provided probability distributions impose a test for theoretical predictions of the static and dynamic moments. The data are interpreted within the shell-model using realistic matrix elements obtained from a G-matrix renormalized CD-Bonn interaction. In view of recent results for the light Sn isotopes the data are discussed in the context of a renormalization of the neutron effective charge. This study is the first to use the reorientation effect for post-accelerated short-lived radioactive isotopes to simultaneously determine the B(E2) and the Q(2 + 1) values.
Nuclear electric quadrupole moments of Rb from the hyperfine spectrum of RbF
The Journal of Chemical Physics, 2006
The molecular beam electric resonance technique has been used to examine the hyperfine spectrum of RbF. The Rb nuclear electric quadrupole interaction, the spin-rotation interactions, and tensor and scalar spin-spin interactions have been measured for both Rb isotopes, including their dependence on vibrational and rotational states. Transition frequencies have been determined to a precision of better than 1 Hz in many cases. The magnetic interactions in the two isotopomers are consistent with what is expected from the known masses and magnetic dipole moments. In the case of the Rb nuclear electric quadrupole interaction, adjustments have been made for a small isotopomer shift, and for the ratio of the effective nuclear electric quadrupole moments, Q͑ 87 Rb͒ / Q͑ 85 Rb͒ = 0.483 830 1 ± 0.000 001 8. The effective quadrupole interaction includes a pseudoquadrupole interaction that may be significant at this level of precision, but cannot be distinguished experimentally.
A self-consistent approach to the quadrupole dynamics of medium heavy nuclei
Nuclear Physics A, 2004
We present a study of the collective quadrupole excitations in some medium heavy transitional nuclei, namely 102 Zr, 104 Mo, 110 Ru, 110 Pd, 124 Xe and 126 Ba, within the frame of a self-consistent model with the Skyrme SIII forces. The full five-dimensional collective dynamics is treated through the Bohr Hamiltonian with mass parameters and moments of inertia calculated microscopically. We discuss consequences stemming from the approximate inclusion of Thouless-Valatin corrections as well as effects of various shapes of the pairing interactions (G force, δ and density dependent δ forces).