1,382 research outputs found

    Calculation of exciton densities in SMMC

    Get PDF
    We develop a shell-model Monte Carlo (SMMC) method to calculate densities of states with varying exciton (particle-hole) number. We then apply this method to the doubly closed-shell nucleus 40Ca in a full 0s-1d-0f-1p shell-model space and compare our results to those found using approximate analytic expressions for the partial densities. We find that the effective one-body level density is reduced by approximately 22% when a residual two-body interaction is included in the shell model calculation.Comment: 10 pages, 4 figure

    Monte Carlo Simulation of Quantum Computation

    Get PDF
    The many-body dynamics of a quantum computer can be reduced to the time evolution of non-interacting quantum bits in auxiliary fields by use of the Hubbard-Stratonovich representation of two-bit quantum gates in terms of one-bit gates. This makes it possible to perform the stochastic simulation of a quantum algorithm, based on the Monte Carlo evaluation of an integral of dimension polynomial in the number of quantum bits. As an example, the simulation of the quantum circuit for the Fast Fourier Transform is discussed.Comment: 12 pages Latex, 2 Postscript figures, to appear in Proceedings of the IMACS (International Association for Mathematics and Computers in Simulation) Conference on Monte Carlo Methods, Brussels, April 9

    Atomic final-state interactions in tritium decay

    Get PDF
    We calculate the effect of the Coulomb interaction of the ejected β ray with the bound atomic electron in the β decay of a tritium atom. The excited state probabilities of the residual helium ion are changed by at most 0.17% from the usual sudden approximation

    Skyrme-force time-dependent Hartree-Fock calculations with axial symmetry

    Get PDF
    We discuss axially symmetric time-dependent Hartree-Fock calculations using a finite-range modification of the Skyrme energy functional. The finite-difference forms of the coordinate-space time-dependent Hartree-Fock equations, the method of time evolution, and other numerical aspects are presented. Detailed results for (^84)Kr-induced deep-inelastic collisions with (^208)Pb at E_(lab) = 494 MeV and with (^209)Bi at E_(lab) = 600 MeV and 714 MeV are compared with experiment. [NUCLEAR REACTIONS (^84)Kr + (^208)Pb at E_lab = 494 MeV and (^84)Kr + (^209)Bi at E_1ab=600 and 714 MeV, in the time-dependent Hartree-Fock approximation. Strongy damped collisions. Details of Skyrme force calculations with axial symmetry.

    Spin-Polarization Response Functions in High-Energy (e,e'p) Reactions

    Get PDF
    Spin-polarization response functions are examined for high-energy (e,ep)(\vec{e},e'\vec{p}) reaction by computing the full 18 response functions for the proton kinetic energy Tp=T_{p'}= 0.515 GeV and 3.179 GeV with an 16O target. The Dirac eikonal formalism is applied to account for the final-state interactions. The formalism is found to yield the response functions in good agreement with those calculated by the partial-wave expansion method at 0.515 GeV. We identify the response functions that depend on the spin-orbital potential in the final-state interactions, but not on the central potential. Dependence on the Dirac- or Pauli-type current of the nucleon is investigated in the helicity-dependent response functions, and the normal-component polarization of the knocked-out proton, PnP_n, is computed.Comment: 22 pages, Latex, figures available at ftp://ftp.krl.caltech.edu/pub/users/rseki/it

    Coupling of phonons to a helium atom adsorbed on graphite

    Get PDF
    We compute the self-energy for a ^4He atom adsorbed on graphite to second order in the phonon coupling. The phonon contributions amount to several degrees Kelvin. The imaginary part corresponds to a lifetime of some 10^(-11) s

    Inversion formula for the internucleus potential using sub-barrier fusion cross sections

    Get PDF
    Subject to the assumption that sub-barrier fusion is described by an effective one-dimensional energy-independent local potential barrier, the Jeffreys-Wentzel-Kramers-Brillouin approximation for the fusion cross sections is inverted to determine this effective potential. Potential barriers, with their associated experimental errors, are presented for ^(13)C+^(13)C and ^(40)Ca+^(40)Ca, and the assumption of a local effective potential is shown to be inadequate for ^(64)Ni+^(64)Ni

    ^7Be(p,γ)^8B cross section and the properties of ^7Be

    Get PDF
    We study the nonresonant part of the ^7Be(p,γ)^8B reaction using a three-cluster resonating group model that is variationally converged and virtually complete in ^4He+^3He+p model space. The importance of using adequate nucleon-nucleon interaction is demonstrated. We find that the low-energy astrophysical S factor is linearly correlated with the quadrupole moment of ^7Be. A range of parameters is found where the most important ^8B, ^7Be, and ^7Li properties are reproduced simultaneously; the corresponding S factor at E_(c.m.)=20 keV is 24.6–26.1 eV b
    corecore