Milagro for Everyone

Introduction

Milagro is the world's first instrument capable of continuously monitoring the entire overhead sky in the TeV energy regime.To achieve this capability a new type of detector had to be developed - a water Cherenkov extensive air shower array. Water Cherenkov detectors had been used in neutrino experiments such as IMB and Kamiokande, and on a small scale in air shower arrays. Milagro is the first example of a large continuous pool being used as a gamma-ray telescope.

The Electromagnetic Universe

Mankind has viewed the heavens for millennia. Until this century we were limited to observing visible photons - commonly known as light. With the advent of radio telescopes, infrared sensors, space satellites equipped with high-energy photon (light) detectors, and ground-based cosmic-ray detectors, we can now observe the Universe over 20 orders of magnitude in photon energy.

Despite these great advances we have only observed a small fraction of the Universe with telescopes that are sensitive to photons with energies near 1 trillion volts (1 TeV). The advent of the Compton Gamma Ray Observatory has shown that this is a particularly exciting region of the spectrum.

Milagro is the first telescope capable of continuously monitoring the Northern sky in this energy range.