Extended sudden approximation modeling of high-energy nucleon-removal reactions

Abstract

Calculations based on the sudden approximation have been performed to describe high-energy single-nucleon removal reactions. Within this approach, which takes as its starting point the formalism developed to describe the breakup of well-developed single-neutron halo systems, the nucleon-removal cross section and the full three-dimensional momentum distributions of the core fragments, including absorption, diffraction, Coulomb, and nuclear-Coulomb interference amplitudes, have been computed. The Coulomb, breakup has been treated to all orders for the dipole interaction. The results are compared here to experimental data for a range of light, neutron-rich $psd$-shell nuclei taken at beam energies of $43--68\phantom{\rule{0.3em}{0ex}}\mathrm{MeV}∕\text{nucleon}$. Good agreement is found for the inclusive cross sections and both the longitudinal and transverse momentum distributions. In the case of $^{17}\mathrm{C}$, comparison is also made with the results of calculations using the transfer-to-the-continuum model. The three-dimensional momentum distributions computed within the sudden approximation model exhibit longitudinal and transverse momentum components that are strongly coupled by the reaction for $s$-wave states, while no such effect is apparent for $d$ waves. Incomplete detection of transverse momenta arising from limited experimental acceptances thus leads to a narrowing of the longitudinal distributions for nuclei with significant $s$-wave valence neutron configurations, as confirmed by the data. Asymmetries in the longitudinal momentum distributions attributed to diffractive dissociation are also explored.