Nonlocal interactions in the (d,p) surrogate method for (n,γ) reactions

Abstract

Background Single-neutron transfer reactions populating states in the continuum are interesting both for structure and astrophysics. In their description often global optical potentials are used for the nucleon-target interactions, and these interactions are typically local. In our work, we study the effects of nonlocality in (d, p) reactions populating continuum states. This work is similar to that of [1] but now for transfer to the continuum.Purpose A theory for computing cross sections for inclusive processes A(d, p)X was explored in [2]. Therein, local optical potentials were used to describe the nucleon-target effective interaction. The goal of the present work is to extend the theory developed in [2] to investigate the effects of including nonlocality in the effective interaction on the relevant reaction observables.Method We implement the R-matrix method to solve the non-local equations both for the nucleon wavefunctions and the propagator. We then apply the method to systematically study the inclusive process of (d, p) on 16 O, 40 Ca, 48 Ca and 208 Pb at 10, 20 and 50 MeV. We compare the results obtained when non-local interactions are used with those obtained when local equivalent interactions are included.Results We find that nonlocality affects different pieces of the model in complex ways. The competition between the reduction of the propagator and the neutron wavefunction in the region of interest and the increase of the magnitude of the interaction produces varying effects on the cross section. Depending on the beam energy and the target, the non-elastic breakup can either increase or decrease. Effects on the heavier targets can be as large as 85%.Conclusions While the non-elastic transfer cross section for each final spin state can change considerably, the main prediction of the model [2], namely the shape of the spin distributions, remains largely unaltered by nonlocality.

Auxetic Tetrahex Carbon with Ultrahigh Strength and a Direct Band Gap

“…Starting with the fully relaxed tetrahex-C structure, uniaxial tensile strain up to 40% at an increment of 1% is applied in either the x (zigzag) or y (armchair) direction to explore its strainstress relation and determine ideal strength (the highest strength of a crystal at 0 K) [32,33] and critical strain (at which ideal strength reaches) [22]. The tensile strain is defined as,…”

Considering non-locality in the optical potentials within eikonal models

“…Even though in their most general form, optical potentials are non-local, many reaction models have not been adapted to deal with this non-locality. It has been shown that non-locality affects strongly transfer observables [17][18][19][20][21][22][23]. Since these studies were limited to low energy, in this work we investigated the importance of these effects in the higher energy regime, the regime for which knockout reactions are typically measured.…”

“…Over the last few years, a large body of work demonstrates that including non-locality explicitly in the optical potential significantly affects the calculated reactions observables [17][18][19][20][21][22][23]. These studies have focused primarily on (d, p) transfer reactions in the energy range E lab < 50 MeV.…”

Prediction of (p,n) Charge-Exchange Reactions with Uncertainty Quantification

“…Typically charge-exchange reactions to the IAS are studied within 1-step DWBA. Models that incorporate more complex reaction dynamics explored in other reac-tion channels, such as transfer reactions and Coulomb dissociation (see [15][16][17][18][19]), could present relevant extensions for improving the theory of charge-exchange reactions to IAS. More importantly, given the advances in uncertainty quantification for reactions [20][21][22][23], it is imperative to quantify the uncertainties in the charge-exchange predictions from theory.…”