Design and operation of the Wide-angle Air Cherenkov Telescope array

Much has been learned about cosmic rays since their discovery near the beginning of the twentieth century. One of the mysteries that still remains is the nature of their source. While theories exist, the ability to observe in the energy range necessary to test the models has been unreachable by cosmic ray instruments until the last few years. Balloon and space based instruments have not been able to measure high enough energies and ground based instruments have not been able to measure low enough energies. In the last few years this gap has narrowed until the energy ranges covered by the balloon and space instruments and the ground instruments just touch. However, no instrument as of yet has been able to bridge the gap and cross over into the other energy range.; In this dissertation I will present the design and first observations of the Wide-angle Air Cherenkov Telescope (WACT) array. The WACT array is a ground based cosmic ray detector capable of measuring cosmic ray particles with energies down to a few TeV well below the upper limit of modern space and balloon based instruments. It consists of six 2 meter telescopes arranged around the Milagro Gamma Ray Observatory in Fenton Hill, NM at an altitude of 2666 meters above sea level. The instrument design, characteristics and response are presented. Additionally, I present the method used to reconstruct the energy and species of the primary cosmic ray particle.; Finally, I will present the data from the first observations made with the WACT array. With these first observations we measured the primary cosmic ray proton flux and present our cosmic ray spectrum along with a comparison other published results. The primary cosmic ray spectrum measured with the initial WACT array data is .