PHYSICAL REVIEW C 75, 037602 (2007) Microscopic optical model potentials for p-nucleus scattering at intermediate energies M. Hemalatha, 1,* Y. K. Gambhir, 1,2,† S. Kailas, 3 and W. Haider 4 1 Department of Physics, I.I.T.-Powai, Mumbai 400076, India 2 Manipal Academy of Higher Education, Manipal 576119, India 3 Nuclear Physics Division, Bhabha Atomic Research Centre, Mumbai 400085, India 4 Department of Physics, Aligarh Muslim University, Aligarh 202002, India (Received 27 December 2006; published 23 March 2007) A comparative study of the microscopic optical potentials viz., semimicroscopic with extended Jeukenne- Lejeune-Mahaux interaction and microscopic Brueckner theory using Hamada-Johnston as well as Urbana V14 soft-core internucleon interactions, has been carried out. These microscopic optical potentials are compared with that of Dirac phenomenology (DP) for the polarized proton- 40 Ca elastic scattering at 35 MeV and 200 MeV. These potentials have different shapes for 200 MeV below 4 fm. In particular, for the real part of the central potential, only the Dirac phenomenology and the microscopic optical potential calculated with the Hamada-Johnston interaction exhibit the well known wine-bottle-bottom shape. It is found that the calculated observables (cross section, analyzing power and spin rotation function) using these potentials having different shapes, compare well with the experiment. DOI: 10.1103/PhysRevC.75.037602 PACS number(s): 24.10.Ht, 25.40.Cm, 24.70.+s It is known that the conventional optical model with phenomenological potential of Woods-Saxon shape fails to account for the spin observables (like analyzing power A y and spin rotation function Q) in the polarised proton-nucleus scattering at intermediate energies. On the other hand, Dirac phenomenology (DP) [1,2] is found to be remarkably success- ful in describing these observables. The most crucial point emerged from this analysis is that the real part of the central potential changes its shape and sign, for example, becoming wine-bottle-bottom (WBB) shape at intermediate energies and then turns repulsive with the further increase in projectile energy. There are other models like the relativistic impulse approximation that are well known to work successfully in the medium- and high-energy regions [3]. It has been shown that the nonrelativistic optical model with microscopically derived potentials can qualitatively reproduce the cross sec- tions and spin observables. For example, Bauge et al. [4] have calculated the nucleon optical potential employing the extended Jeukenne, Lejeune, and Mahaux (JLM) interaction while similar calculations by Haider et al. [5] (Saliem et al. [6]) have been carried out within the framework of the first order Brueckner theory using Hamada-Johnston (HJ) [7] (Urbana V14 soft-core [8]) internucleon interaction. It is seen that both these calculations ([4] and [8]) yield very mild WBB shape for the real central optical potential at a radial distance close to root-mean-square radius of the target nucleus while the corresponding DP and HJ potentials have a prominent WBB shape. In this short communication as an illustration, we examine the scattering of polarized proton on 40 Ca. We analyze the results obtained from semimicroscopic approach using extended JLM interaction (MOM) [4] valid up to 200 MeV projectile energy and microscopic Brueckner theory with * Electronic address: hema@phy.iitb.ac.in † Electronic address: yogy@phy.iitb.ac.in Hamada-Johnston [7] as well as Urbana V14 [8] inter-nucleon potentials (denoted by HJ and V14, respectively) and compare with those of the Dirac phenomenology (DP). The physical quantities of interest are the elastic scattering angular distributions and the spin observables. In the elastic scattering of spin 1 2 projectiles, the differential cross section (σ (θ )), the analyzing power (A y ) and the spin rotation function (Q) are given by the standard well known expressions [9]. A brief description of different models for generating the nucleon-nucleus optical potential used in the present analysis now follows. The semimicroscopic optical model (MOM) [4] is a Lane-consistent, optical model potential which is built by folding radial matter densities with an effective interaction in nuclear matter that is based on the extension of the original approach proposed by JLM. This interaction is a hybrid in which the energy- and density-dependent, spin-independent interaction in nuclear matter comes from the original work of JLM, with a new parametrization defined in [10]. In MOM, the imaginary part of the effective interaction is multiplied by an effective mass. The JLM interaction, established for nuclear matter, has been applied to finite nuclei by using the improved local density approximation (LDA) and is also extended to deformed nuclei. To calculate the complex spin-orbit potential, Scheerbaum’s prescription coupled with the phenomenological complex potential depths was used as shown in Ref. [10]. This yields through the standard code MOM [4], both real and imaginary central and spin-orbit parts of the optical potential. This optical potential is then used to get the elastic scattering differential cross section, analyzing power and spin rotation function. Such an analysis of the scattering and the reaction data has been successfully employed in the past [4,11–15]. Here we use this approach for the analysis of the elastic proton scattering on 40 Ca. All the required parameters along with the energy-dependent normalisation factors for the various terms of the optical potential given in Ref. [4] are 0556-2813/2007/75(3)/037602(4) 037602-1 ©2007 The American Physical Society