Search for Correlated High Energy Cosmic Ray Events with CHICOS

Abstract

We present the results of a search for time correlations in high energy cosmic ray data (primary E > 10^{14} eV) collected by the California HIgh school Cosmic ray ObServatory (CHICOS) array. Data from 60 detector sites spread over an area of 400 km^2 were studied for evidence of correlated events separated by more than 1 km with coincidence times ranging from 1 microsec up to 1 second. All searches were consistent with the absence of excess coincidences except for a 2.9 sigma excess observed for coincidence times less than 10 microsec. We report upper limits for the coincidence probability as a function of coincidence time.