Milagro as a solar observatory

The Milagro Gamma Ray Observatory, a ground-based water Čherenkov detector designed primarily for observing very high energy gamma ray sources, can also be used to study the Sun. Measurements of high energy emission from solar flares can lead to an understanding of the solar energetic particle acceleration mechanism(s), and Milagro, with enhanced data acquisition electronics, will measure solar cosmic rays in the poorly studied energy range from 10 to 300 GeV. Monte Carlo simulations show that proton and neutron solar cosmic rays at these energies will be detectable at the ground level through the single muons and/or mini showers they produce. Milagro can detect these events in a scaler counting mode similar to that of a neutron monitor. Additionally, it can operate in a telescope mode that reduces background by pointing at the source region. We also report a preliminary detection, using the Milagro prototype, Milagrito, of a ground level event (GLE) on 6 November 1997 associated with an X-class solar flare.