Knock-out of 2p protons from the interior of 90Zr
Abstract
The momentum distributions for the knock-out of 2p protons from 90Zr leading to the ground state and the excited state at 1.507 MeV in 89Y have been determined at two outgoing proton energies (70 and 100 MeV) in a high-resolution (e,e′p) experiment. Using elastic proton-nucleus scattering data as a constraint, a proper description of the (e,e′p) data is obtained if the optical potential used to calculate the final state interaction is more absorptive inside the nucleus at 100 MeV than at 70 MeV. The deduced strength and orbit radii are compared to theory and to the result of a (d, 3He) experiment.
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Cited by (9)
Nuclear Data Sheets for A = 89
2013, Nuclear Data SheetsThe evaluated experimental data are presented for 14 known nuclides of mass 89 (Ge, As, Se, Br, Kr, Rb, Sr, Y, Zr, Nb, Mo, Tc, Ru, Rh). New data on high–spin excitations are available for 89Kr, 89Rb, 89Sr, 89Tc and 89Ru, including a superdeformed structure in 89Tc. Fluorescence studies in 89Y have revealed a large number of new levels in 7–11 MeV range. New two–neutron transfer data are available for 89Zr. New direct and precise measurement of atomic masses of 89Se, 89Br, 89Kr, 89Rb, 89Mo and 89Tc have greatly improved the Q value landscape in this mass region. This work supersedes previous A=89 evaluation published in 1998Si31, and also the older ones 1989Si20, 1975Ko21, and M.W. Johns et al., Nuclear Data Tables A 8, 373 (1970).
In spite of extensive experimental work on the isobaric nuclei of this mass chain several deficiencies remain. The identification of 89Rh isotope remains unconfirmed. The half–lives of ground states of 89Ge, 89As and 89Rh have not been measured, only the lower limits are estimated from time–of–flight in a reaction and experimental arrangement, where produced and identified. The decay schemes of 89Ge, 89As, 89Se, 89Ru and 89Rh are not known, and those for 89Tc and 89Mo are incomplete. High–lying (neutron unbound) levels in 89Kr, expected to be populated in the decay of 89Br, have not been investigated. The spins and parities for levels in 89Kr are largely unassigned, while for 89Tc and 89Ru, only few low–spin excitations are established. For 89Rb, little information is available for high–spin structures. Detailed gamma–ray data are available for 88Sr(n,γ)89Sr reaction, but most of these γ rays remain unassigned in a level scheme. Excited state data are nonexistent for 89Ge, 89As, 89Se, 89Br and 89Rh. The 89Y and 89Zr are the most extensively studied nuclei in A=89.
Nuclear data sheets for A = 89
1998, Nuclear Data SheetsThe evaluated experimental data are presented for 14 known nuclides of mass 89 (Ge, As, Se, Br, Kr, Rb, Sr, Y, Zr, Nb, Mo, Tc, Ru, Rh). Excited state data are nonexistent for89Ge,89As,89Se,89Br,89Ru, and89Br. High-spin excitations are known for89Sr,89Y,89Zr,89Nb,89Mo and89Tc; neutron capture ;gg-ray data are available for89Sr (neutrons at thermal energy); and particle-transfer data exist for89Rb,89Sr,89Y,89Nb and89Mo. This work supersedes earlier A = 89 Nuclear Data Sheets (89Si20, 75Ko21).
Nuclear response beyond mean field theory
1990, Nuclear Physics, Section AAn extension of the RPA equations is derived, with emphasis on the relation between the single-particle Green function and the polarization propagator. Including second order self-energy contributions the resulting particle-hole interaction includes the coupling to two-particle-two-hole (2p2h) states and the resulting response satisfies relevant conservation laws. This aspect of the theory is shown to be essential to obtain reliable and meaningful results for excitation strengths and to avoid ghost solutions. This method is applied to electromagnetic and charge exchange excitations in 48Ca up to 100 MeV. A G-matrix interaction based on meson exchange is used which takes care of short-range correlations. The results compare favourably with measured excitation strengths and electromagnetic form factors both at low energy as well as in the giant resonance region. Remaining discrepancies point in the direction of further strength reduction due to shortrange correlations as well as a possible stronger coupling to 2p2h states at low energy.
Aspects of the final-state interaction and long-range correlations in quasi-elastic (e, e′p) and (e, e′n) reactions
1989, Nuclear Physics, Section AWe present quasi-elastic (e, e′p) and (e, e′n) cross sections as obtained within a self-consistent Hartree-Fock (HF) and continuum random-phase approximation (RPA) model. A Skyrme type interaction is used, for which the momentum-dependence is studied in detail. Calculations are performed for the nuclei 12C and 16O in parallel and perpendicular kinematics. We investigate in how far a HF-RPA reaction model can account for the final-state interaction (FSI) in (e, e′p) and (e, e′n) processes in a realistic way. Furthermore, the effect of the RPA correlations on the cross sections is discussed. We confront the results of our calculations with the available 12C data.
Single-particle properties and short-range correlations in nuclear matter
1989, Nuclear Physics, Section ALadder correlations are studied with inclusion of hole-hole propagation to all orders. The resulting effective interaction is separated into a forward-going and a backward-going contribution with the numerical use of dispersion relations. This procedure allows the correct calculation of the corresponding self-energy terms. Self-consistency between the ladders and the self-energy is established for the quasi-particle energy. Calculations are performed with semi-realistic interactions derived from Reid's soft-core interaction to avoid the appearance of pairing instabilities. A careful study of the complete momentum and energy dependence of the resulting self-energy is made for various densities. Effective mass contributions are studied coming from both the k- and ω-dependence of the self-energy. Accurate calculation of all relevant spectral functions is performed with proper fulfillment of the sum rule and quasi-particle properties are discussed. An important fraction of the single-particle strength is found at very high energy due to the realistic short-range repulsion in the interaction. From the hole spectral function the momentum distribution is calculated at various densities. The depletion due to the influence of short-range correlations around normal nuclear matter density amounts to about 13%.
Neutron spectroscopic factors in <sup>208</sup>Pb from the proton decay of the <sup>208</sup>Bi isobaric analog state
1989, Physics Letters BAccurate spectroscopic factors for neutron removal from 208Pb, leading to single neutron hole states in 207Pb, are derived from the escape widths of the isobaric analog state of the 208Pb ground state in 208Bi. The accuracy of the analysis, which follows a new procedure, is discussed. Derived lower limits on the occupancies of neutron orbitals in 208Pb are and a lower limit 0.7 ().