Generator coordinate method calculations of one-nucleon removal reactions on40Ca

Abstract

An approach to the Generator Coordinate Method (GCM) using Skyrme-type effective forces and Woods-Saxon construction potential is applied to calculate the single-particle proton and neutron overlap functions in 40 Ca. The relationship between the boundstate overlap functions and the one-body density matrix has been used. These overlap functions are applied to calculate the cross sections of one-nucleon removal reactions such as (e, e ′ p), (γ, p) and (p, d) on 40 Ca on the same theoretical footing. A consistent description of data for the different reactions is achieved. The shapes of the experimental cross sections for transitions to the 3/2 + ground state and the first 1/2 + excited state of the residual nuclei are well reproduced by the overlap functions obtained within the GCM. An additional spectroscopic factor accounting for correlations not included in the overlap function must be applied to the calculated results to reproduce the size of the experimental cross sections. I. INTRODUCTIONExperiments on nuclear reactions accompanied by one-nucleon removal from 40 Ca (e.g. [1][2][3][4]) have accumulated much spectroscopic information on its nucleon-hole spectral density function and, generally, on the single-particle aspects of nuclear structure. From the theoretical point of view two topics in the analyses of these processes are of significant interest and have been mainly studied: the reaction mechanism and the ground-state correlation effects. The latter can be successfully considered by using the unique relationship between the overlap functions (OF) related to bound states of the (A − 1)-particle system and the one-body density matrix (ODM) of the A-particle system in its ground state [5]. This makes it possible to investigate the effects of the various types of nucleon-nucleon correlations included 1 in the ODM on the bound-state proton and neutron overlap functions.In our recent works [6,7] a consistent study of overlap functions and one-nucleon removal reactions on 16 O using different correlation methods has been carried out and the comparison with the experimental data has been performed. In our previous calculations we used methods which account mainly for short-range and tensor nucleon-nucleon correlations. It is desirable, however, to take into consideration also correlations originating from the collective motion of the nucleons. This was partially done for the 16 O nucleus in [7]. In this respect, the various applications of the Generator Coordinate Method to nuclear problems [8-10] have shown its efficiency as a potential source of information on nucleon-nucleon correlations in nuclei. The results on the one-and two-body density and momentum distributions, occupation probabilities and natural orbitals obtained within the GCM using various construction potentials [10] have shown that the nucleon-nucleon correlations accounted for in this method are different from the short-range ones and are rather related to the collective motion of the nucleons. It was pointed out that these correlations are a...

Quasifree (e,e′p) reactions on nuclei with neutron excess

“…The short-range and tensor correlations, which arise from the characteristics of the bare nucleon-nucleon interaction, account for a reduction factor of at most 10%-15% [49][50][51][52][53][54]. The remaining, and larger, part of the quenching is due to long-range correlations related to the coupling between s.p.…”

Meson exchange currents in electromagnetic one-nucleon emission

“…This approach was originally proposed in Ref. [24] and has more recently been applied to the (γ, p) reaction [16,29] and, in a relativistic model, to the (e, e ′ p) and (γ, p) reactions [30]. In these previous applications, however, only the pion-seagull term was included in the two-body current.…”

“…Moreover, in Refs. [16,24,29] a simplified treatment of the spin was used in order to reduce the complexity of the numerical calculations, and the spin-orbit term was neglected in the optical potential.…”

Jastrow-type calculations of one-nucleon removal reactions on opens−dshell nuclei

“…Initially, the procedure has been applied [6] to a model OBDM [7] accounting for SRC within the low-order approximation (LOA) to the Jastrow correlation method [8]. First, the applicability of the theoretically calculated overlap functions has been tested in the description of the 16 O(p, d) pickup reaction [9,10] and of the 40 Ca(p, d) reaction [9,11]. The main result from these investigations is that absolute cross sections of the (p, d) reactions are evaluated without any additional normalization in contrast to standard Distorted Wave Born Approximation (DWBA) calculations.…”

“…The main result from these investigations is that absolute cross sections of the (p, d) reactions are evaluated without any additional normalization in contrast to standard Distorted Wave Born Approximation (DWBA) calculations. Then, a detailed study of the cross sections of the electron-and photon-induced knockout reactions on 16 O [12] and 40 Ca [11] has been performed. The (e, e ′ p) and (γ, p) reactions are more suitable to test various single-particle (SP) overlap functions and NN correlations.…”