975 research outputs found
Similarity Renormalization Group for Few-Body Systems
Internucleon interactions evolved via flow equations yield soft potentials
that lead to rapid variational convergence in few-body systems.Comment: 3 pages, 6 figures. To appear in the proceedings of the 20th European
Conference on Few-Body Problems in Physics (EFB20), Pisa, September 10-14,
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Prediction Model for the Life of Nickel-cadmium Batteries in Geosynchronous Orbit Satellites
A mathematical model is described which predicts the service life of nickel-cadmium batteries designed for geosynchronous orbit satellites. Regression analysis technique is used to analyze orbital data on second generation trickle charged batteries. The model gives average cell voltage as a function of design parameters, operating parameters and time. The voltage model has the properties of providing a good fit to the data, good predictive capability, and agreement with known battery performance characteristics. Average cell voltage can be predicted to within 0.02 volts for up to 8 years. This modeling shows that these batteries will operate reliably for 10 years. Third-generation batteries are expected to operate even longer
Similarity Renormalization Group for Nucleon-Nucleon Interactions
The similarity renormalization group (SRG) is based on unitary
transformations that suppress off-diagonal matrix elements, forcing the
hamiltonian towards a band-diagonal form. A simple SRG transformation applied
to nucleon-nucleon interactions leads to greatly improved convergence
properties while preserving observables, and provides a method to consistently
evolve many-body potentials and other operators.Comment: 5 pages, 6 figures (8 figure files); references updated and
acknowledgment adde
Release of Hemoglobin and Potassium from Human Red Blood Cells Treated with Triton X-100 Under the Critical Micellar Concentration
The action of detergents is thought to be connected primarily with micelle formation. However, detergent monomers can also effect biological systems. It was found in this study that human red blood cells can be disintegrated with Triton X-100 non-ionic detergent at a concentration of 0.007 %, lower than the critical micellar concentration (CMC). The time dependent release of hemoglobin and potassium was detected at 37°C and both were sigmoid in character. Although potassium was released faster than hemoglobin, a cooperative relationship between potassium and hemoglobin within the intact red blood cell is suggested by this observation
Low momentum nucleon-nucleon potential and shell model effective interactions
A low momentum nucleon-nucleon (NN) potential V-low-k is derived from meson
exhange potentials by integrating out the model dependent high momentum modes
of V_NN. The smooth and approximately unique V-low-k is used as input for shell
model calculations instead of the usual Brueckner G matrix. Such an approach
eliminates the nuclear mass dependence of the input interaction one finds in
the G matrix approach, allowing the same input interaction to be used in
different nuclear regions. Shell model calculations of 18O, 134Te and 135I
using the same input V-low-k have been performed. For cut-off momentum Lambda
in the vicinity of 2 fm-1, our calculated low-lying spectra for these nuclei
are in good agreement with experiments, and are weakly dependent on Lambda.Comment: 5 pages, 5 figure
Two-pion-exchange contributions to the pp\to pp\pi^0 reaction
Our previous study of the near-threshold pp\to pp\pi^0 reaction based on a
hybrid nuclear effective field theory is further elaborated by examining the
momentum dependence of the relevant transition operators. We show that the
two-pion exchange diagrams give much larger contributions than the one-pion
exchange diagram, even though the former is of higher order in the Weinberg
counting scheme. The relation between our results and an alternative counting
scheme, the momentum counting scheme, is also discussed.Comment: 11 pages, minor change, a few references are adde
Block Diagonalization using SRG Flow Equations
By choosing appropriate generators for the Similarity Renormalization Group
(SRG) flow equations, different patterns of decoupling in a Hamiltonian can be
achieved. Sharp and smooth block-diagonal forms of phase-shift equivalent
nucleon-nucleon potentials in momentum space are generated as examples and
compared to analogous low-momentum interactions ("v_lowk").Comment: 4 pages, 9 figures (pdfLaTeX
Microscopically-based energy density functionals for nuclei using the density matrix expansion: Implementation and pre-optimization
In a recent series of papers, Gebremariam, Bogner, and Duguet derived a
microscopically based nuclear energy density functional by applying the Density
Matrix Expansion (DME) to the Hartree-Fock energy obtained from chiral
effective field theory (EFT) two- and three-nucleon interactions. Due to the
structure of the chiral interactions, each coupling in the DME functional is
given as the sum of a coupling constant arising from zero-range contact
interactions and a coupling function of the density arising from the
finite-range pion exchanges. Since the contact contributions have essentially
the same structure as those entering empirical Skyrme functionals, a
microscopically guided Skyrme phenomenology has been suggested in which the
contact terms in the DME functional are released for optimization to
finite-density observables to capture short-range correlation energy
contributions from beyond Hartree-Fock. The present paper is the first attempt
to assess the ability of the newly suggested DME functional, which has a much
richer set of density dependencies than traditional Skyrme functionals, to
generate sensible and stable results for nuclear applications. The results of
the first proof-of-principle calculations are given, and numerous practical
issues related to the implementation of the new functional in existing Skyrme
codes are discussed. Using a restricted singular value decomposition (SVD)
optimization procedure, it is found that the new DME functional gives
numerically stable results and exhibits a small but systematic reduction of our
test function compared to standard Skyrme functionals, thus justifying
its suitability for future global optimizations and large-scale calculations.Comment: 17 pages, 6 figure
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