Suppression of the centrifugal barrier effects in the off-energy-shell neutron+$^{17}$O interaction

TL;DR

This study extends the Trojan Horse Method to neutron-induced reactions, demonstrating its ability to bypass centrifugal barrier effects and accurately measure resonance contributions in the $^{17}$O(n,α)$^{14}$C reaction.

Contribution

It introduces an extension of the Trojan Horse Method to neutron reactions, enabling the observation of resonances suppressed by centrifugal barriers in direct measurements.

Findings

The $^{18}$O excited state at 8.125 MeV was observed in THM but not in direct measurements.

First measurement of angular distributions for resonances in this reaction.

THM effectively overcomes centrifugal barrier suppression in neutron-induced reactions.

Abstract

The reaction $^{17}$O($n,\alpha$)$^{14}$C was studied at energies from $E_{cm}=0$ to $E_{cm}=350$ keV using the quasi-free deuteron break-up in the three body reaction $^{17}$O$+d \rightarrow \alpha+ ^{14}$C$+p$, extending the Trojan Horse indirect method (THM) to neutron-induced reactions. It is found that the $^{18}$O excited state at $E^*=8.125 \pm 0.002$ MeV observed in THM experiments is absent in the direct measurement because of its high centrifugal barrier. The angular distributions of the populated resonances have been measured for the first time. The results unambiguously indicate the ability of the THM to overcome the centrifugal barrier suppression effect and to pick out the contribution of the bare nuclear interaction.