Measurement of the Total Cross Section for $\gamma n \rightarrow p \pi^-$ Near Threshold at MAX-lab

In nuclear science, researchers strive to describe the properties of the nucleons using the framework provided by QCD. A number of theoretical approaches to solving the QDC equations for nuclear processes exist. The predictions of these theories can be compared with the results from accurate experimental measurements for those nuclear reactions where both theory and experiment can provide accurate answers. One such reaction is pion photoproduction near threshold. A measurement of the total cross-section very close to threshold for the $\gamma + n \rightarrow p + \pi^- $ reaction is currently being performed using the Tagged Photon Facility at MAX-lab in Lund, Sweden. A LD$_2$ target was used to provide the neutron target. Due to the target thickness, the $\pi^-$ were not detected directly but instead were captured on another nucleus in the target. This capture resulted in a nominal 128 MeV $\gamma$-ray approximately 25\% of the time. This gamma-ray easily exited the target and was detected using three large NaI(Tl) detectors: CATS, BUNI, and DIANA. An overview of the measurement and preliminary results from the June 2011 run period will be presented.