This grant will support research which addresses the interest generated in the field of cosmic ray physics by reports of point sources - possibly neutron stars in space - of Ultra High Energy (UHE) gamma rays detected by conventional ground based Extensive Air Shower (EAS) arrays. The investigator plans measurements of the distribution of gamma rays from space. He will work at the University of Notre Dame with two postdoctoral associates and a team of graduate and undergraduate students. The array uses a new concept involving position sensitive detectors which, it is claimed, provides superior angular resolution by directly measuring individual angles of the charged secondaries in the air showers. This array "Gamma Ray Astronomy at Notre Dame" (GRAND) consists of 16 stations. Each station is made up of eight planes, each with area 1.25 square meters, of position sensitive detectors spaced vertically. The bottom two planes are separated from the top six by a thin steel absorber used to distinguish muons from electrons or soft secondary photons. Crucial features of the array then are smaller angular resolution and good muon, electron and soft photon identification.
