Measurement of single $\pi^0$ production by coherent neutral-current $\nu$ Fe interactions in the MINOS Near Detector

TL;DR

This paper measures the cross section of single neutral pion production via coherent neutral-current neutrino interactions in an iron-carbon target using the MINOS Near Detector, providing data at high atomic mass and energy.

Contribution

It presents the first measurement of this process in a high-$ ext{A}$ target at energies around 5 GeV, confirming model predictions.

Findings

Total cross section measured as 77.6±5.0(stat)^{+15.0}_{-16.8}(syst)×10^{-40}cm^2 per nucleus.

Clear excess of events at very forward angles in the production angle distribution.

Results agree well with the Berger-Sehgal model predictions.

Abstract

Forward single $\pi^0$ production by coherent neutral-current interactions, $\nu \mathcal{A} \to \nu \mathcal{A} \pi^0$, is investigated using a 2.8$\times 10^{20}$ protons-on-target exposure of the MINOS Near Detector. For single-shower topologies, the event distribution in production angle exhibits a clear excess above the estimated background at very forward angles for visible energy in the range~1-8 GeV. Cross sections are obtained for the detector medium comprised of 80% iron and 20% carbon nuclei with $\langle \mathcal{A} \rangle = 48$, the highest-$\langle \mathcal{A} \rangle$ target used to date in the study of this coherent reaction. The total cross section for coherent neutral-current single-$\pi^0$ production initiated by the $\nu_\mu$ flux of the NuMI low-energy beam with mean (mode) $E_{\nu}$ of 4.9 GeV (3.0 GeV), is $77.6\pm5.0\,(\text{stat}) ^{+15.0}_{-16.8}\,(\text{syst})\times10^{-40}\,\text{cm}^2~\text{per nucleus}$. The results are in good agreement with predictions of the Berger-Sehgal model.