D. J. Dean

Spin-dependent neutralino-nucleus scattering for A ∼ 127 nuclei

We perform nuclear shell model calculations of the neutralino-nucleus cross section for several nuclei in the A=127 region. Each of the four nuclei considered is a primary target in a direct dark matter detection experiment. The calculations are valid for all relevant values of the momentum transfer. Our calculations are performed in the 3s2d1g{sub 7/2}1h{sub 11/2} model space using extremely large bases, allowing us to include all relevant correlations. We also study the dependence of the nuclear response upon the assumed nuclear Hamiltonian and find it to be small. We find good agreement with the observed magnetic moment as well as other obervables for the four nuclei considered: {sup 127}I, {sup 129,131}Xe, and {sup 125}Te. {copyright} {ital 1997} {ital The American Physical Society}

Coupled Cluster Calculations of Ground and Excited States of Nuclei

The standard and renormalized coupled cluster methods with singles, doubles, and noniterative triples and their generalizations to excited states, based on the equation of motion coupled cluster approach, are applied to the 4He and 16O nuclei. A comparison of coupled cluster results with the results of the exact diagonalization of the Hamiltonian in the same model space shows that the quantum chemistry inspired coupled cluster approximations provide an excellent description of ground and excited states of nuclei. The bulk of the correlation effects is obtained at the coupled cluster singles and doubles level. Triples, treated noniteratively, provide the virtually exact description.

Origin of the anomalous long lifetime of 14C

We report the microscopic origins of the anomalously suppressed beta decay of ¹⁴C to ¹⁴N using the ab initio no-core shell model with the Hamiltonian from the chiral effective field theory including three-nucleon force terms. The three-nucleon force induces unexpectedly large cancellations within the p shell between contributions to beta decay, which reduce the traditionally large contributions from the nucleon-nucleon interactions by an order of magnitude, leading to the long lifetime of ¹⁴C.

Shell-model Monte Carlo studies of {ital fp}-shell nuclei

We study the gross properties of even-even and {ital N}={ital Z} nuclei with {ital A}=48--64 using shell-model Monte Carlo methods. Our calculations account for all 0{h_bar}{omega} configurations in the {ital fp} shell and employ the modified Kuo-Brown interaction {ital KB}3. We find good agreement with data for masses and total {ital B}({ital E}2) strengths, the latter employing effective charges {ital e}{sub {ital p}}=1.35{ital e} and {ital e}{sub {ital n}}=0.35{ital e}. The calculated total Gamow-Teller strengths agree consistently with the {ital B}({ital GT}{sub +}) values deduced from ({ital n},{ital p}) data if the shell-model results are renormalized by 0.64, as has already been established for {ital sd}-shell nuclei. The present calculations therefore suggest that this renormalization (i.e., {ital g}{sub {ital A}}=1 in the nuclear medium) is universal.

Coupled-cluster approach to nuclear physics

Using many-body perturbation theory and coupled-cluster theory, we calculate the ground-state energy of He-4 and O-16. We perform these calculations using a no-core G-matrix interaction derived from a realistic nucleon-nucleon potential. Our calculations employ up to two-particle-two-hole coupled-cluster amplitudes.

Ab-initio coupled-cluster study of 16O.

We report converged results for the ground and excited states and matter density of 16O using realistic two-body nucleon-nucleon interactions and coupled-cluster methods and algorithms developed in quantum chemistry. Most of the binding is obtained with the coupled-cluster singles and doubles approach. Additional binding due to three-body clusters (triples) is minimal. The coupled-cluster method with singles and doubles provides a good description of the matter density, charge radius, charge form factor, and excited states of a one-particle, one-hole nature, but it cannot describe the first-excited 0(+) state. Incorporation of triples has no effect on the latter finding.

How magic is the magic68Ninucleus

We calculate the low-lying

Unblocking of the Gamow-Teller Strength in Stellar Electron Capture on Neutron-Rich Germanium Isotopes

{B(E2,0}_{\mathrm{g}.\mathrm{s}.}^{+}\ensuremath{\rightarrow}{2}_{\mathrm{f}}^{+})

Effective interactions and the nuclear shell-model

distribution of strength in

Pairing correlations in N ∼ Z pf-shell nuclei

{}^{68}\mathrm{Ni}