Measuring TeV cosmic rays at the High Altitude Water Cherenkov Observatory

Department of Physics and Astronomy, University of Rochester, Rochester, NY, USA

^a e-mail: sybenzvi@pas.rochester.edu

Published online: 8 December 2015

Abstract

The High-Altitude Water Cherenkov Observatory, or HAWC, is an air shower array designed to observe cosmic rays and gamma rays between 100 GeV and 100 TeV. HAWC, located between the peaks Sierra Negra and Pico de Orizaba in central Mexico, will be completed in the spring of 2015. However, the observatory has been collecting data in a partial configuration since mid-2013. With only part of the final array in data acquisition, HAWC has already accumulated a data set of nearly 100 billion air showers. These events are used to calibrate the detector angular reconstruction using the shadow of the Moon, and to measure the anisotropy in the arrival directions of cosmic rays above 1 TeV. Using data recorded between June 2013 and July 2014, we have observed a significant 10⁻⁴ anisotropy consisting of three statistically significant “hotspots” in the cosmic ray flux. We will discuss these first results from HAWC and compare them to previous measurements of anisotropy in the northern and southern sky.