# Cross Section for $\gamma n \to \pi^0 n$ measured at Mainz/A2

## TL;DR

This study measures the differential cross section for gamma-neutron to pi-zero-neutron reactions across a broad energy range, providing new data that enhances understanding of reaction dynamics and resonance properties.

## Contribution

It presents the first detailed measurement of the reaction on the neutron with extensive energy and angular coverage, including the extraction of photon decay amplitudes at resonance poles.

## Key findings

- Data agree with previous measurements but extend to lower energies
- Provided the first determination of photon decay amplitudes at resonance poles
- Extended partial-wave analyses with new experimental data

## Abstract

The $\gamma n \to \pi^0 n$ differential cross section evaluated for 27 energy bins span the photon-energy range 290-813 MeV (W = 1.195-1.553 GeV) and the pion c.m. polar production angles, ranging from 18 deg to 162 deg, making use of model-dependent nuclear corrections to extract pi0 production data on the neutron from measurements on the deuteron target. Additionally, the total photoabsorption cross section was measured. The tagged photon beam produced by the 883-MeV electron beam of the Mainz Microtron MAMI was used for the 0-meson production. Our accumulation of 3.6 x 10^6 $\gamma n \to \pi^0 n$ events allowed a detailed study of the reaction dynamics. Our data are in reasonable agreement with previous A2 measurements and extend them to lower energies. The data are compared to predictions of previous SAID, MAID, and BnGa partial-wave analyses and to the latest SAID fit MA19 that included our data. Selected photon decay amplitudes $N^* \to \gamma n$ at the resonance poles are determined for the first time.