It was also necessary to move detector one into an upright position (directly above the target) as this is the position we expect to get full coincidences. The MCA was used to make sure that coincidences were were only counted for photons paired with a Compton scattered 0.511 MeV photon, as well as to check for background noise and to compare full spectrum of both detectors.
Data
Full spectrum runs were done at two hour interval for both detectors to check that photons were being detected at proper energy intervals as would be expected for 0.511 MeV photons being Compton scattered from a target at 90 degrees.