Improved implementation of the transfer-to-the-continuum method for single-neutron knockout reactions and the validity of standard approximations

Abstract

Approximations made in implementing the transfer-to-the-continuum model for single-nucleon knockout reactions on light target nuclei are investigated using more complete numerical calculations. The reliability of different proposed approximation schemes and their predicted cross sections are discussed. The results of the model calculations that use realistic descriptions of the distorting interactions entering the theory are also compared with available experimental data for reactions induced by $^{15}\mathrm{C}$ and $^{34}\mathrm{Si}$ secondary beams. These transitions, with different neutron orbital angular momenta, also have significantly different values of the neutron separation energy. The different approximation schemes are shown to agree most closely for the weakly bound and spatially extended, $l=0,^{15}\mathrm{C}$ ground state transition. For an $l=2$ transition in $^{34}\mathrm{Si}$, the approximation schemes are shown to be dependent on the nucleon separation energy. In all cases comparisons of even the most accurate implementation of the theory with the experimental data reveals deviations in both the magnitudes of the predicted integrated cross sections and their momentum distributions. Furthermore, the use of the different approximation schemes also produce quite significant effects on the shapes of the predicted momentum distributions and the integrated partial cross sections.