New Limits on Diffuse Galactic Emission of Gamma Rays with Energies above 10$^{14}$ eV
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- Session 65 -- The Galaxy and Galactic ISM
- Oral presentation, Thursday, 2, 1994, 10:00-11:30
[65.01] New Limits on Diffuse Galactic Emission of Gamma Rays with Energies above 10$^{14}$ eV
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C.E.Covault, A.Borione, J.W.Cronin, B.E.Fick, L.F.Fortson, K.G.Gibbs,B.J.Newport, T.A.McKay, R.A.Ong, L.J Rosenberg (EFI,U of Chicago), M.Catanese, K.D.Green, A.Kennedy, J.Matthews, D.Nitz, D.Sinclair, J.C. van der Velde (U of Michigan), D.B.Kieda (U of Utah)
The Chicago Air Shower Array (CASA) operates in coincidence with the
Michigan muon array (MIA), and is sensitive to gamma rays with
energies $\simgreat 100$ TeV. We describe a search for diffuse gamma
ray emission from molecular cloud regions which are located within 10
degrees of the galactic plane as seen from the northern hemisphere.
The emission mechanism and spatial distribution of diffuse gamma rays
at 100 TeV should be similar to gamma rays detected at 100 MeV
energies by the EGRET experiment aboard the Compton Gamma Ray
Observatory. CASA-MIA is well suited to discriminate against hadronic
background cosmic rays, based upon the muon content of air showers.
We search for diffuse gamma rays by seeking an excess of muon-poor
showers from the direction of candidate source regions. Current flux
limits are beginning to approach predictions for diffuse emission
based upon a uniform distribution of cosmic rays in the galaxy.
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