32,408 research outputs found
Exploiting the Circadian Clock for Improved Cancer Therapy: Perspective From a Cell Biologist
Pairing and realistic shell-model interactions
This paper starts with a brief historical overview of pairing in nuclei,
which fulfills the purpose of properly framing the main subject. This concerns
the pairing properties of a realistic shell-model effective interaction which
has proved very successful in describing nuclei around doubly magic 132Sn. We
focus attention on the two nuclei 134Te and 134Sn with two valence protons and
neutrons, respectively. Our study brings out the key role of one particle-one
hole excitations in producing a significant difference between proton and
neutron pairing in this region
Low-momentum nucleon-nucleon interaction and shell-model calculations
We discuss the use of the low-momentum nucleon-nucleon NN interaction V-low-k
in the derivation of the shell-model effective interaction and emphasize its
practical value as an alternative to the Brueckner G-matrix method. We present
some selected results of our current study of exotic nuclei around closed
shells, which have been obtained starting from the CD-Bonn potential. We also
show some results of calculations performed with different phase-shift
equivalent NN potentials, and discuss the effect of changes in the cutoff
momentum which defines the V-low-k potential.Comment: 5 pages, 5 figures, 1 table, Talk presented at CDN05, 31 Jan - 4 Feb
2005, University of Tokyo, Japa
Shell-model study of the N=82 isotonic chain with a realistic effective hamiltonian
We have performed shell-model calculations for the even- and odd-mass N=82
isotones, focusing attention on low-energy states. The single-particle energies
and effective two-body interaction have been both determined within the
framework of the time-dependent degenerate linked-diagram perturbation theory,
starting from a low-momentum interaction derived from the CD-Bonn
nucleon-nucleon potential. In this way, no phenomenological input enters our
effective Hamiltonian, whose reliability is evidenced by the good agreement
between theory and experiment.Comment: 7 pages, 11 figures, 3 tables, to be published in Physical Review
Shell-model studies on exotic nuclei around 132Sn
The study of exotic nuclei around 132Sn is a subject of current experimental
and theoretical interest. Experimental information for nuclei in the vicinity
of 132Sn, which have been long inaccessible to spectroscopic studies, is now
available thanks to new advanced facilities and techniques. The experimental
data which have been now become available for these neutron-rich nuclei may
suggest a modification in the shell structure. They are, in fact, somewhat
different from what one might expect by extrapolating the existing results for
N<82, and as a possible explanation a change in the single-proton level scheme
has been suggested. The latter would be caused by a more diffuse nuclear
surface, and could be seen as a precursor of major effects which should show up
at larger neutron excess. New data offer therefore the opportunity to test the
shell model and look for a possible evolution of shell structure when going
toward neutron drip line. This is stimulating shell-model studies in this
region. Here, we present an overview of recent shell-model studies of 132Sn
neighbors, focusing attention on those calculations employing realistic
effective interactions.Comment: 8 pages, 4 tables, invited talk at INPC2007, Tokyo, Japan, June 3-8
2007. To be published in Nuclear Physics
Remote monitoring of a thermal plume
A remote-sensing experiment conducted on May 17, 1977, over the Surry nuclear power station on the James River, Virginia is discussed. Isotherms of the thermal plume from the power station were derived from remotely sensed data and compared with in situ water temperature measurements provided by the Virginia Electric and Power Company, VEPCO. The results of this study were also qualitatively compared with those from other previous studies under comparable conditions of the power station's operation and the ambient flow. These studies included hydraulic model predictions carried out by Pritchard and Carpenter and a 5-year in situ monitoring program based on boat surveys
Shell-model study of quadrupole collectivity in light tin isotopes
A realistic shell-model study is performed for neutron-deficient tin isotopes
up to mass A=108. All shell-model ingredients, namely two-body matrix elements,
single-particle energies, and effective charges for electric quadrupole
transition operators, have been calculated by way of the many-body perturbation
theory, starting from a low-momentum interaction derived from the
high-precision CD-Bonn free nucleon-nucleon potential. The focus has been put
on the enhanced quadrupole collectivity of these nuclei, which is testified by
the observed large B(E2;0+ -> 2+)s. Our results evidence the crucial role
played by the Z=50 cross-shell excitations that need to be taken into account
explicitly to obtain a satisfactory theoretical description of light tin
isotopes. We find also that a relevant contribution comes from the calculated
neutron effective charges, whose magnitudes exceed the standard empirical
values. An original double-step procedure has been introduced to reduce
effectively the model space in order to overcome the computational problem.Comment: 6 pages, 6 figures, 2 table
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