The large area high resolution gamma ray astrophysics facility HR-GRAF

Abstract

The main objective of this long term program is the development of the prototype of a space‐based, large area High Resolution Gamma Ray Astrophysics Facility (HR‐GRAF) capable of studying diffuse and point‐like sources of gamma rays in the 1 MeV to 100 GeV energy range with a high angular and energy resolution, and very large sensitivity. The design of the HR‐GRAF will be based on the High Resolution Gamma Ray Telescope (HRGT) developed by the University of Texas at Dallas and University of California, Los Angeles, collaboration for SDIO.The long term studies planned for HR‐GRAF to be flown first either in balloons or free fliers, and eventually in the Space Station are the following:1) Map the galactic gamma radiation with better angular and energy resolution2) Observation of characteristic angular variations in the diffuse gamma rays to identify the primary origin of this radiation as due to discrete structures3) Study of point like sources of MeV and GeV gamma rays 4) Study the structure of the Galactic Center and test the hypothesis of the existence of a massive black hole there5) Obtain some additional information on gamma ray bursters and on the possibility that gamma ray bursts may be originated by exotic objects6) Search for gamma rays from the decay and annihilation of cold dark matter particles. Special emphasis will be given to the search for gamma ray lines in the 1−100 GeV range from the annihilation of weakly interacting, neutral, heavy Majorana fermions, such as photinos or higgsinos7) Obtain some additional information on nulear gamma ray lines. The large area HR‐GRAF will complement and extend the experimental studies to be carried out with GRO COMPTEL and GRO EGRET by introducing into gamma ray astrophysics high resolution detection technologies which were developed quite recently or are under development in high energy accelerator physics.