New Results in the CBF theory for medium-heavy nuclei

Momentum distributions, spectroscopic factors and quasi-hole wave functions of medium-heavy doubly closed shell nuclei have been calculated in the framework of the Correlated Basis Function theory, by using the Fermi hypernetted chain resummation techniques. The calculations have been done by using microscopic two-body nucleon-nucleon potentials of Argonne type, together with three-body interactions. Operator dependent correlations, up to the tensor channels, have been used.Comment: 6 pages, 3 figures, proceeding of the "XI Convegno su problemi di Fisica Nucleare Teorica" 11-14 Ottobre 2006, Cortona, Ital

Nuclear re-interaction effects in quasi-elastic neutrino nucleus scattering

The quasi-elastic neutrino-nucleus cross section has been calculated by using a Fermi gas model corrected to consider the re-scattering between the emitted nucleon and the rest nucleus. As an example of the relevance of this effect we show results for the muon production cross section on 16O target.Comment: 7 pages, 4 Postscript figures, Contribution to NuInt01 Workshop, KEK, Tsukuba, Japa

Renormalized Fermi hypernetted chain approach in medium-heavy nuclei

The application of the Correlated basis function theory and of the Fermi hypernetted chain technique, to the description of the ground state of medium-heavy nuclei is reviewed. We discuss how the formalism, originally developed for symmetric nuclear matter, should be changed in order to describe finite nuclear systems, with different number of protons and neutrons. This approach allows us to describe doubly closed shell nuclei by using microscopic nucleon-nucleon interactions. We presents results of numerical calculations done with two-nucleon interactions of Argonne type,implemented with three-body forces of Urbana type. Our results regard ground-state energies, matter, charge and momentum distributions, natural orbits, occupation numbers, quasi-hole wave functions and spectroscopic factors of 12C, 16O, 40Ca, 48Ca and 208Pb nuclei.Comment: 127 Pages, 37 figures, Accepted for publication in Physics Report

Low-lying magnetic excitations of doubly-closed-shell nuclei and nucleon-nucleon effective interactions

We have studied the low lying magnetic spectra of 12C, 16O, 40Ca, 48Ca and 208Pb nuclei within the Random Phase Approximation (RPA) theory, finding that the description of low-lying magnetic states of doubly-closed-shell nuclei imposes severe constraints on the spin and tensor terms of the nucleon-nucleon effective interaction. We have first made an investigation by using four phenomenological effective interactions and we have obtained good agreement with the experimental magnetic spectra, and, to a lesser extent, with the electron scattering responses. Then we have made self-consistent RPA calculations to test the validity of the finite-range D1 Gogny interaction. For all the nuclei under study we have found that this interaction inverts the energies of all the magnetic states forming isospin doublets.Comment: 19 pages, 13 figures, 7 tables, accepted for publication in Phys. Rev.

Evolution of the pygmy dipole resonance in nuclei with neutron excess

The electric dipole excitation of various nuclei is calculated with a Random Phase Approximation phenomenological approach. The evolution of the strength distribution in various groups of isotopes, oxygen, calcium, zirconium and tin, is studied. The neutron excess produces $E1$ strength in the low energy region. Indexes to measure the collectivity of the excitation are defined. We studied the behavior of proton and neutron transition densities to determine the isoscalar or isovector nature of the excitation. We observed that in medium-heavy nuclei the low-energy $E1$ excitation has characteristics rather different that those exhibited by the giant dipole resonance. This new type of excitation can be identified as pygmy dipole resonance.Comment: 14 pages, 12 figures, 7 table

Effects of state dependent correlations on nucleon density and momentum distributions

The proton momentum and density distributions of closed shell nuclei are calculated within a model treating short--range correlations up to first order in the cluster expansion. The validity of the model is verified by comparing the results obtained with purely scalar correlations with those produced by finite nuclei Fermi Hypernetted Chain calculations. State dependent correlations are used to calculate momentum and density distributions of 12C, 16O, 40Ca, and 48Ca, and the effects of their tensor components are studied.Comment: 16 pages, latex, 8 figures, accepted for publication in Phys. Rev.

Evolution of the pygmy dipole resonance in nuclei with neutron excess

The electric dipole excitation of various nuclei is calculated with a Random Phase Approximation phenomenological approach. The evolution of the strength distribution in various groups of isotopes, oxygen, calcium, zirconium and tin, is studied. The neutron excess produces $E1$ strength in the low energy region. Indexes to measure the collectivity of the excitation are defined. We studied the behavior of proton and neutron transition densities to determine the isoscalar or isovector nature of the excitation. We observed that in medium-heavy nuclei the low-energy $E1$ excitation has characteristics rather different that those exhibited by the giant dipole resonance. This new type of excitation can be identified as pygmy dipole resonance.Comment: 14 pages, 12 figures, 7 table

Supply and Demand Management under Inducement of Price Discounts – A Monte Carlo Simulation Analysis

This paper considered a single-item, three-echelon (supplier, retailer, and customer) inventory problem. At random times, the supplier offers the retailer a discount. The inter-arrival times of discounts are exponentially distributed. For the retailer, whether or not to take a discount offer depends on its inventory level. If inventory is below threshold level S, the retailer will order to replenish inventory up to S+Q units. Otherwise, the retailer will pass. At the regular purchase price, the retailer uses the order-up-to reorder point inventory system. The reorder point is r, and the order-up-to quantity is R. The demand of the customer is price-elastic. Depending on its inventory level, the retailer may discounts its selling price to boost up demand. The decision variables are S, Q, R, r, and the selling prices (regular and discount selling price). The simulation experiment covered reasonable range of values for each decision variable. Each run represented one scenario, i.e., one combination of the decision variables