High resolution measurements of cosmic-ray air showers with the track imaging cerenkov experiment

The Track Imaging Cerenkov Experiment (TrICE) is a prototype imaging atmospheric C erenkov telescope designed to use a high resolution method for measuring cosmic-ray composition at TeV-PeV energies. The method aims to separate the fast and compact direct Cerenkov signal produced by primary cosmic-ray nuclei in the upper atmosphere from the light produced by the subsequent air shower cascade. Efficient discrimination of the direct Cerenkov signal benefits from the use of small camera pixels to improve the angular resolution of the air shower image. Multi-anode photomultipliers are used in the TrICE camera to achieve 0.086 pixel spacing over a 1.5 field of view. The telescope was completed in late 2006 at Argonne National Laboratory. We present the results from the first observations with TrICE.