# Near-threshold $\pi^-$ photoproduction on the deuteron

## TL;DR

This paper reports the first experimental measurement of the near-threshold cross section for incoherent $^-$ photoproduction on the deuteron, providing new data to test theoretical models of the elementary reaction and final-state interactions.

## Contribution

It presents the first experimental measurement of the near-threshold $^-$ photoproduction cross section on the deuteron, using gamma-ray detection techniques.

## Key findings

- Measured total cross section for $^-$ photoproduction near threshold.
- Compared experimental data with theoretical models of elementary reactions.
- Provided insights into pion-nucleon and nucleon-nucleon final-state interactions.

## Abstract

The first experimental investigation of the near-threshold cross section for incoherent $\pi^-$ photoproduction on the deuteron $\gamma$ d -> $\pi^-$ pp is presented. The experimental technique involved detection of the ~131 MeV gamma ray resulting from the radiative capture of photoproduced $\pi^-$ in the target. The total cross section has been measured using an unpolarized tagged-photon beam, a liquid-deuterium target, and three very large NaI(Tl) spectrometers. The data are compared to theoretical models that give insight into the elementary reaction $\gamma$ n -> $\pi^-$ p and pion-nucleon and nucleon-nucleon final-state interactions.