Search for the Eta-Mesic Nucleus From Photo-Production on 3 He in CLAS

Once particles were identified, fiducial cuts were applied to define regions of the detectors with uniform efficiency, and momentum corrections were applied to correct for energy losses as the particles moved though the detector. We further reduced our volume of events by only looking at specific three-particle coincidences: a forwardgoing proton (with an angle of less than 25° from the photon beam) occurring with another proton and π - . These last two particles represent a specific decay mode of the collapsed eta-mesic nucleus, as shown in Figure 2. In order to conserve the small momentum found in the eta-mesic nucleus, these two particles must be produced back-to-back to each other, with angles between 160 and 180. These cuts formed a specific volume of data to be analyzed.