700 research outputs found

    Systematics of intermediate-energy single-nucleon removal cross sections

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    There is now a large and increasing body of experimental data and theoretical analyses for reactions that remove a single nucleon from an intermediate-energy beam of neutron- or proton-rich nuclei. In each such measurement, one obtains the inclusive cross section for the population of all bound final states of the mass A-1 reaction residue. These data, from different regions of the nuclear chart, and that involve weakly- and strongly-bound nucleons, are compared with theoretical expectations. These calculations include an approximate treatment of the reaction dynamics and shell-model descriptions of the projectile initial state, the bound final states of the residues, and the single-particle strengths computed from their overlap functions. The results are discussed in the light of recent data, more exclusive tests of the eikonal dynamical description, and calculations that take input from more microscopic nuclear structure models.Comment: 4 pages, 1 figure, with reference correcte

    Cooper pair correlations and energetic knock-out reactions

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    Two-nucleon removal (or knock-out) reactions at intermediate energies are a developing tool for both nuclear spectroscopy and for the study of certain nucleon correlations in very exotic and some stable nuclei. We present an overview of these reactions with specific emphasis on the nature of the two-nucleon correlations that can be probed. We outline future possibilities and tests needed to fully establish these sensitivities.Comment: 12 pages, 3 figures: Contribution to the Volume 50 years of Nuclear BCS edited by World Scientifi

    Matter radii of light halo nuclei

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    We re-examine the matter radii of diffuse halo nuclei, as deduced from reaction cross section measurements at high energy. Careful consideration is given to the intrinsic few-body structure of these projectiles and the adiabatic nature of the projectile-target interaction. Using 11^{11}Li, 11^{11}Be and 8^{8}B as examples we show that data require significantly larger matter radii than previously reported. The revised value for 11^{11}Li of 3.55 fm is consistent with three-body models with significant 1s1s-intruder state components, which reproduce experimental 9^{9}Li momentum distributions following 11^{11}Li breakup, but were hitherto thought to be at variance with cross section data.Comment: 8 pages RevTeX plus 5 Postscript figures. Figures also available at http://www.ph.surrey.ac.uk/scnp/jakpub/figures.html Scheduled tentatively for 13May96 issue of Phys. Rev. Let

    Spectroscopy studies using two-nucleon knockout

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    MOMDIS: a Glauber model computer code for knockout reactions

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    A computer program is described to calculate momentum distributions in stripping and diffraction dissociation reactions. A Glauber model is used with the scattering wavefunctions calculated in the eikonal approximation. The program is appropriate for knockout reactions at intermediate energy collisions (30 MeV ≤\leq Elab/_{lab}/nucleon ≤2000\leq 2000 MeV). It is particularly useful for reactions involving unstable nuclear beams, or exotic nuclei (e.g. neutron-rich nuclei), and studies of single-particle occupancy probabilities (spectroscopic factors) and other related physical observables. Such studies are an essential part of the scientific program of radioactive beam facilities, as in for instance the proposed RIA (Rare Isotope Accelerator) facility in the US.Comment: 22 pages. Accepted for publication in Computer Physics Communications. Code available from CPC web sit

    Microscopic two-nucleon overlaps and knockout reactions from 12^{12}C

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    The nuclear structure dependence of direct reactions that remove a pair of like or unlike nucleons from a fast 12^{12}C projectile beam are considered. Specifically, we study the differences in the two-nucleon correlations present and the predicted removal cross sections when using pp-shell shell-model and multi-ℏω\hbar\omega no-core shell-model (NCSM) descriptions of the two-nucleon overlaps for the transitions to the mass AA=10 projectile residues. The NCSM calculations use modern chiral two-nucleon and three-nucleon (NN+3N) interactions. The npnp-removal cross sections to low-lying TT=0, 10^{10}B final states are enhanced when using the NCSM two-nucleon amplitudes. The calculated absolute and relative partial cross sections to the low energy 10^{10}B final states show a significant sensitivity to the interactions used, suggesting that assessments of the overlap functions for these transitions and confirmations of their structure could be made using final-state-exclusive measurements of the npnp-removal cross sections and the associated momentum distributions of the forward travelling projectile-like residues.Comment: 9 pages, 7 figure
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