Integral measurement of the $^{12}$C(n,p)$^{12}$B reaction up to 10 GeV

TL;DR

This paper reports the first integral measurement of the $^{12}$C(n,p)$^{12}$B reaction cross section from 13.6 MeV to 10 GeV at CERN, comparing experimental results with various simulation models and evaluations.

Contribution

It provides the first comprehensive integral cross section measurement of the $^{12}$C(n,p)$^{12}$B reaction up to 10 GeV, using activation and time-of-flight techniques at n_TOF.

Findings

GEANT4 simulations underestimate $^{12}$B production.

TALYS-1.6 with optimized parameters accurately reproduces measured cross sections.

The neutron flux above 200 MeV was reevaluated based on recent cross section data.

Abstract

The integral measurement of the $^{12}$C(n,p)$^{12}$B reaction was performed at the neutron time of flight facility n_TOF at CERN. The total number of $^{12}$B nuclei produced per neutron pulse of the n_TOF beam was determined using the activation technique in combination with a time of flight technique. The cross section is integrated over the n_TOF neutron energy spectrum from reaction threshold at 13.6 MeV to 10 GeV. Having been measured up to 1 GeV on basis of the $^{235}$U(n,f) reaction, the neutron energy spectrum above 200 MeV has been reevaluated due to the recent extension of the cross section reference for this particular reaction, which is otherwise considered a standard up to 200 MeV. The results from the dedicated GEANT4 simulations have been used to evaluate the neutron flux from 1 GeV up to 10 GeV. The experimental results related to the $^{12}$C(n,p)$^{12}$B reaction are compared with the evaluated cross sections from major libraries and with the predictions of different GEANT4 models, which mostly underestimate the $^{12}$B production. On the contrary, a good reproduction of the integral cross section derived from measurements is obtained with TALYS-1.6 calculations, with optimized parameters.