diffuse emission from regions of the Galactic plane, have sensitivity to see known TeV active galactic nuclei and the brightest known GeV gamma-ray bursts, and represents a large enough step in sensitivity to likely discover new phenomena. Because HAWC has a 2 steradian instantaneous field of view, it will observe diffuse gamma-ray emission from the plane of the galaxy over a broad range of galactic longitudes reaching to the galactic center. In September 2015, a Laboratory Directed Research and Development grant was awarded to Brenda Dingus of Los Alamos National Laboratory to improve HAWC's effective area and sensitivity by adding an array outrigger tanks, surrounding the larger central tanks. Due to the greater size of particle showers created by high energy cosmic rays, increasing the area of the detector will increase the sensitivity of the detector. The outriggers were predicted to increase the sensitivity and effective area of HAWC by 2 to 4 times for particles with energies above 10 TeV. The outrigger array was completed in early 2018, a year later than expected. Principle of operation HAWC detects electromagnetic radiation from air showers produced by high energy cosmic rays which hit the Earth's atmosphere. HAWC is sensitive to showers produced by primary cosmic rays with energies between 100 GeV and 50 TeV. Cherenkov radiation occurs when charged particles travel through a medium at a speed faster than the speed of light in that medium. High-energy gamma rays, upon striking the upper atmosphere, can create positron-electron pairs that move at great speeds. The residual effect of these particles traveling through the atmosphere can result in a cascading shower of particles and photons that are aimed towards the surface at predictable angles. HAWC consists of large metal tanks, 7.3 m wide by 5 m high, containing a light-tight bladder holding 188,000 liters of water. Inside are four photomultiplier tubes (3-8" and 1-10" high QE). High-energy particles striking the water result in Cherenkov light that is detected by the photomultiplier tubes. HAWC uses the difference in arrival times of the light at different tanks to measure the direction of the primary particle. The pattern of light allows for discrimination between primary (hadrons) and gamma-rays. From this, scientists can map the sky using gamma-rays. Performance goals HAWC will: Detect a large sample of localized gamma-ray sources and measure their spectra and variability to characterize TeV scale acceleration mechanisms from an ensemble of sources.