HAWC erects tank 250

The High Altitude Water Cherenkov (HAWC) gamma-ray detector, of which Georgia Tech is a member has installed tank #250. HAWC operates by measuring ground level particles that are created when a very-high-energy gamma-ray strikes the upper atmosphere. Each of the HAWC tanks works as a "pixel" in 20,000 square meter camera. Building tank 250 meets the construction milestone set by the National Science Foundation and the Department of Energy. Construction will continue, past the mileston, to achive the goal of 300 tanks. HAWC is already operating continously (up time above 95%), with 111 tanks and has observed a dozen very high energy sources including the Crab nebula and active galactic nucleus Mrk 421.