8 research outputs found
On the 21Na(p,gamma)22Mg thermonuclear rate for 22Na production in novae
Classical novae are potential sources of gamma-rays, like the 1.275 MeV gamma
emission following 22Na beta decay, that could be detected by appropriate
instruments on board of future satellites like INTEGRAL. It has been shown that
the production of 22Na by novae is affected by the uncertainty on the
21Na(p,gamma)22Mg rate and in particular by the unknown partial widths of the
Ex = 5.714 MeV, J^pi = 2^+, 22Mg level. To reduce these uncertainties, we
performed shell model calculations with the OXBASH code, compared the results
with available spectroscopic data and calculated the missing partial widths.
Finally, we discuss the influence of these results on the 21Na(p,gamma)22Mg
reaction rate and 22Na synthesis.Comment: To appear in Phys. Rev. C, 6 pages with 3 figure
Isovector multiphonon excitations in near spherical nuclei
The lowest isoscalar and isovector quadrupole and octupole excitations in
near spherical nuclei are studied within the the proton-neutron version of the
interacting boson model including quadrupole and octupole bosons (sdf-IBM-2).
The main decay modes of these states in near spherical nuclei are discussed.Comment: 4 pages, 1 figure, LaTeX, sprocl, epsfig. Proc. Int. Conf. on
Structure of the Nucleus at the Dawn of the Century (Bologna, 29 May - 3 June
2000); in pres
SU(3) realization of the rigid asymmetric rotor within the IBM
It is shown that the spectrum of the asymmetric rotor can be realized quantum
mechanically in terms of a system of interacting bosons. This is achieved in
the SU(3) limit of the interacting boson model by considering higher-order
interactions between the bosons. The spectrum corresponds to that of a rigid
asymmetric rotor in the limit of infinite boson number.Comment: 9 pages, 2 figures, LaTeX, epsfi
Interrelation between the isoscalar octupole phonon and the proton-neutron mixed-symmetry quadrupole phonon in near spherical nuclei
The interrelation between the octupole phonon and the low-lying
proton-neutron mixed-symmetry quadrupole phonon in near-spherical nuclei is
investigated. The one-phonon states decay by collective E3 and E2 transitions
to the ground state and by relatively strong E1 and M1 transitions to the
isoscalar 2+ state. We apply the proton-neutron version of the Interacting
Boson Model including quadrupole and octupole bosons (sdf-IBM-2). Two F-spin
symmetric dynamical symmetry limits of the model, namely the vibrational and
the \gamma-unstable ones, are considered. We derive analytical formulae for
excitation energies as well as B(E1), B(M1), B(E2) and B(E3) values for a
number of transitions between low-lying states.Comment: 25 pages, 3 figures, LaTeX, epsfig. Nucl. Phys. A (in press
Microscopic Shell Model Calculations for sd-Shell Nuclei
Several techniques now exist for performing detailed and accurate calculations of the structure of light nuclei, i.e., A ≤ 16. Going to heavier nuclei requires new techniques or extensions of old ones. One of these is the so-called No Core Shell Model (NCSM) with a Core approach, which involves an Okubo-Lee-Suzuki (OLS) transformation of a converged NCSM result into a single major shell, such as the sd-shell. The obtained effective two-body matrix elements can be separated into core and single-particle (s.p.) energies plus residual two-body interactions, which can be used for performing standard shell-model (SSM) calculations. As an example, an application of this procedure will be given for nuclei at the beginning ofthe sd-shell
Precision mass measurements of V and V for nucleon-nucleon interaction studies
We discuss the motivation and technique of Penning trap mass spectrometry applied to radioactiveV and^{44}^{m}V, using the LEBIT 9.4 T Penning trap mass spectrometer at the National Superconducting Cyclotron Laboratory (NSCL) at Michigan State University. A complementary measurement of these nuclides, performed at the CSRe in Lanzhou, China, was recently published, but with errors several times larger than obtainable for a short-lived radionuclide in a Penning trap. Interpretation of the higher precision results is ongoing and a full accounting of this measurement is anticipated in the coming months