Many-body effects in 16O(e,e'p)

Effects of nucleon-nucleon correlations on exclusive $(e,e'p)$ reactions on closed-shell nuclei leading to single-hole states are studied using $^{16}O(e,e'p)^{15}N$ ($6.32$ MeV, $3/2^-$) as an example. The quasi-hole wave function, calculated from the overlap of translationally invariant many-body variational wave functions containing realistic spatial, spin and isospin correlations, seems to describe the initial state of the struck proton accurately inside the nucleus, however it is too large at the surface. The effect of short-range correlations on the final state is found to be largely cancelled by the increase in the transparency for the struck proton. It is estimated that the values of the spectroscopic factors obtained with the DWIA may increase by a few percent due to correlation effects in the final state.Comment: 21 Pages, PHY-7849-TH-9

Highly deformed 40^{40}Ca configurations in 28^{28}Si + 12^{12}C

The possible occurrence of highly deformed configurations in the $^{40}$Ca di-nuclear system formed in the $^{28}$Si + $^{12}$C reaction is investigated by analyzing the spectra of emitted light charged particles. Both inclusive and exclusive measurements of the heavy fragments (A $\geq$ 10) and their associated light charged particles (protons and $\alpha$ particles) have been made at the IReS Strasbourg {\sc VIVITRON} Tandem facility at bombarding energies of $E_{lab} (^{28}$Si) = 112 MeV and 180 MeV by using the {\sc ICARE} charged particle multidetector array. The energy spectra, velocity distributions, and both in-plane and out-of-plane angular correlations of light charged particles are compared to statistical-model calculations using a consistent set of parameters with spin-dependent level densities. The analysis suggests the onset of large nuclear deformation in $^{40}$Ca at high spin.Comment: 33 pages, 11 figure

Overlap functions in correlation methods and quasifree nucleon knockout from 16^{16}O

The cross sections of the ($e,e'N$) and ($\gamma,p$) reactions on $^{16}$O are calculated, for the transitions to the $1/2^{-}$ ground state and the first $3/2^{-}$ excited state of the residual nucleus, using single-particle overlap functions obtained on the basis of one-body density matrices within different correlation methods. The electron-induced one-nucleon knockout reaction is treated within a nonrelativistic DWIA framework. The theoretical treatment of the ($\gamma,p$) reaction includes both contributions of the direct knockout mechanism and of meson-exchange currents. The results are sensitive to details of the different overlap functions. The consistent analysis of the reaction cross sections and the comparison with the experimental data make it possible to study the nucleon--nucleon correlation effects.Comment: 26 pages, LaTeX, 5 Postscript figures, submitted to PR

Evaluation of resonance parameters for neutron interaction with iron isotopes for energies up to 400 keV

The evaluation of the resolved resonance parameters of iron isotopes 54, 56, and 57 in the neutron energy region below 400 keV is documented. Estimates of the uncertainties in the resonance parameters and correlation between the partial widths GAMMA/sub n/ and GAMMA/sub ..gamma../ are given when significant. Some details about the procedures used to evaluate the resonance parameters, their uncertainties, and correlations are reported. This evaluation was performed for the general-purpose file of the Evaluated Nuclear Data File (ENDF/B-V MAT 1326). 4 figures, 7 tables

Spectrum unfolding by the least-squares methods

The method of least squares is briefly reviewed, and the conditions under which it may be used are stated. From this analysis, a least-squares approach to the solution of the dosimetry neutron spectrum unfolding problem is introduced. The mathematical solution to this least-squares problem is derived from the general solution. The existence of this solution is analyzed in some detail. A chi/sup 2/-test is derived for the consistency of the input data which does not require the solution to be obtained first. The fact that the problem is technically nonlinear, but should be treated in general as a linear one, is argued. Therefore, the solution should not be obtained by iteration. Two interpretations are made for the solution of the code STAY'SL, which solves this least-squares problem. The relationship of the solution to this least-squares problem to those obtained currently by other methods of solving the dosimetry neutron spectrum unfolding problem is extensively discussed. It is shown that the least-squares method does not require more input information than would be needed by current methods in order to estimate the uncertainties in their solutions. From this discussion it is concluded that the proposed least-squares method does provide the best complete solution, with uncertainties, to the problem as it is understood now. Finally, some implications of this method are mentioned regarding future work required in order to exploit its potential fully

Uncertainty analysis of dosimetry spectrum unfolding

The propagation of uncertainties in the input data is analyzed for the usual dosimetry unfolding solution. A new formulation of the dosimetry unfolding problem is proposed in which the most likely value of the spectrum is obtained. The relationship of this solution to the usual one is discussed

A FORTRAN PROGRAM FOR CALCULATING THE SCATTERING OF NUCLEONS FROM A NONLOCAL OPTICAL POTENTIAL

The listing of a FORTRAN program for calculating the scattering of nucleons from a nonlocal optical potential is given. The mathematical formulation of the problem is presented, together with the numerical methods used in the code. The input to the program is explained, and a brief functional description of each subroutine of the code is included. (auth

Natural nickel and sup60sup 60Ni neutron elastic and inelastic scattering cross sections from 4.07 to 8.56 MeV

Measured neutron elastic and inelastic scattering cross sections for natural nickel between 4.07 and 8.56 MeV are presented and compared with the elastic differertial cross sections of Holmqvist and Wiedling and with ENDF/B III MAT 1123. The elastic differential cross sections are in general agreemert with those of Holmqvist and Wiedling but our angle-integrated differertial elastic cross sections are systemati cally higher by about 10% than those of Holmqvist and Wiedling above 4.6 MeV, a situation found in comparing the two sets of data for other elements. The ENDF/B II1 MAT 1123 elastic angular distributions are found to be in poor agreement with experimertal results from 4 to 8.5 MeV, though the ENDF/B III MAT 1123 angle-integrated differertial elasti c cross sections agree generally within experimertal uncertairties with our results over this energy range. Additional measurements of /sup 60/Ni neutron elastic and inelastic scattering cross sections at 4.34 and 4.92 MeV are given and compared with previous results from 6 to 8.5 MeV and with natural nickel results. Agreement is shown to be excellent. Inelastic scattering cross sections to the 1.450 MeV level in sup 58/Ni are computed from the natural nickel and /sup 60/Ni data. An evaporation model of inelastic scattering to levels of excitation energy in the residual nucleus below 6 MeV is found to be of questionable validity. (auth

sup63sup 63Cu and sup65sup 65Cu neutron elastic and inelastic scattering cross sections from 5.50 to 8.50 MeV

Measured neutron elastic and inelastic scattering cross sections for / sup 63/Cu and /sup 65/Cu between 5.50 and 8.50 MeV are presented and compared with elastic data of Holmqvist and Wiedling and with ENDF/B III MAT 1085 and 1086. The elastic differential cross sections are in fair agreement with those of Holmqvist and Wiedling in shape. The angle-integrated differential elastic cross sections are systematically higher by as much as 28% than those of Holmqvist and Wiedling above 5 MeV, a situation similar to that found in comparing the two sets of data for other elements. ENDF/B III MAT 1085 and 1086 angular distributions underestimate the elastic forward peak below 20 deg. when compared with experimental results and display unphysical fluctuations due to the use of a Legendre series of order 20 where order 9 is the highest required by the data. An evaporation model with temperature ranging from 0.8 to 1.05 MeV reasonably describes inelastic scattering to levels in the residual copper nuclei of excitation energy above 3.2 MeV. (auth