A. P. Zuker

Microscopic mass formulas

By assuming the existence of a pseudopotential smooth enough to do Hartree-Fock variations and good enough to describe nuclear structure, we construct mass formulas that rely on general scaling arguments and on a schematic reading of shell model calculations. Fits to 1751 known binding energies for {ital N},{ital Z}{ge}8 lead to rms errors of 375 keV with 28 parameters. Tests of the extrapolation properties are passed successfully. The Bethe-Weizsaecker formula is shown to be the asymptotic limit of the present one(s). The surface energy of nuclear matter turns out to be probably smaller than currently accepted.

Full pf shell model study of A =48 nuclei

Exact diagonalizations with a minimally modified realistic force lead to detailed agreement with measured level schemes and electromagnetic transitions in [sup 48]Ca, [sup 48]Sc, [sup 48]Ti, [sup 48]V, [sup 48]Cr, and [sup 48]Mn. Gamow-Teller strength functions are systematically calculated and reproduce the data to within the standard quenching factor. Their fine structure indicates that fragmentation makes much strength unobservable. As a by-product, the calculations suggest a microscopic description of the onset of rotational motion. The spectroscopic quality of the results provides strong arguments in favor of the general validity of monopole corrected realistic forces, which is discussed.

Realistic collective nuclear Hamiltonian

The residual part of the realistic forces{emdash}obtained after extracting the monopole terms responsible for bulk properties{emdash}is strongly dominated by pairing and quadrupole interactions, with important {sigma}{tau}{center_dot}{sigma}{tau}, octupole, and hexadecapole contributions. Their forms retain the simplicity of the traditional pairing plus multipole models, while eliminating their flaws through a normalization mechanism dictated by a universal {ital A}{sup {minus}1/3} scaling. Coupling strengths and effective charges are calculated and shown to agree with empirical values. Comparisons between different realistic interactions confirm the claim that they are very similar. {copyright} {ital 1996 The American Physical Society.}

A full 0h̵ω description of the 2νββ decay of 48Ca

Abstract The lifetime of the 2ν double beta decay of 48Ca is computed, using the wave functions obtained in full fp-shell calculations of 48Ca, 48Sc and 48Ti. The resulting double beta transition amplitude MGT2v = 0.040(MeV)−1 leads to a value T 1 2 = 5.5 × 10 19 yr , compatible with the experimental bound of T 1 2 > 3.6 × 10 19 yr .

Isobaric Multiplet Yrast Energies and Isospin Nonconserving Forces

The isovector and isotensor energy differences between yrast states of isobaric multiplets in the lower half of the pf region are quantitatively reproduced in a shell model context. The isospin nonconserving nuclear interactions are found to be at least as important as the Coulomb potential. Their isovector and isotensor channels are dominated by J=2 and J=0 pairing terms, respectively. The results are sensitive to the radii of the states, whose evolution along the yrast band can be accurately followed.

Three-body monopole corrections to realistic interactions.

It is shown that a very simple three-body monopole term can solve practically all the spectroscopic problems-in the p, sd, and pf shells-that were hitherto assumed to need drastic revisions of the realistic potentials.

A Full 0 h-bar omega description of the 2 neutrino beta beta decay of Ca-48

Abstract The lifetime of the 2ν double beta decay of 48Ca is computed, using the wave functions obtained in full fp-shell calculations of 48Ca, 48Sc and 48Ti. The resulting double beta transition amplitude MGT2v = 0.040(MeV)−1 leads to a value T 1 2 = 5.5 × 10 19 yr , compatible with the experimental bound of T 1 2 > 3.6 × 10 19 yr .

Shell-model Monte Carlo studies of neutron-rich nuclei in the 1s-0d-1p-0f shells

We demonstrate the feasibility of realistic shell-model Monte Carlo (SMMC) calculations spanning multiple major shells, using a realistic interaction whose bad saturation and shell properties have been corrected by a newly developed general prescription. Particular attention is paid to the approximate restoration of translational invariance. The model space consists of the full sd-pf shells. We include in the study some well-known T=0 nuclei and several unstable neutron-rich ones around N=20,28. The results indicate that SMMC calculations can reproduce binding energies, B(E2) transitions, and other observables with an interaction that is practically parameter free. Some interesting insight is gained into the nature of deep correlations. The validity of previous studies is confirmed.

On the microscopic derivation of a mass formula

Abstract To analyze the steps leading to exact solutions of the Schrodinger equation, we proceed as if we were to do shell-model calculations in valence spaces defined by carefully specified doubly-magic cores. First we sketch the coupled-cluster formalism as a general framework. Then we separate the hamiltonian H = Hm + HM (m = monopole, M = multipole or residual) by constructing explicitly Hm, entirely responsible for self-consistency aspects. Next we construct renormalized hamiltonians H = Hm + HM Hm describes the core and single-particle energies. It also contains quadratic effects. The core energies are incorporated in a smooth function E(SLD)of liquid-drop (LD) form. Shell effects emerge as a residual part of Hm plus contributions due to configuration mixing through HM. Deformed nuclei are treated phenomenologically, by invoking the extraordinary simplicity of their energy patterns, and elementary arguments about their structure. A general mass formula is presented. It is shown that a minimal version of its bring down the r.m.s. deviation (in a fit to N, Z > 20 nuclei) from 2.5–3 MeV for an LD form to 900 keV (800 keV) by the adjunction of only two (three) parameters. The work of Duflo (preceding paper) is examined and to a large extent vindicated. Study of the data provides firm evidence that the full specification of Hm contains the clue to further progress.

Mirror displacement energies and neutron skins

A gross estimate of the neutron skin