The calibration of the compton spectrometer and imager for the 2014 balloon campaign

The Compton Spectrometer and Imager (COSI) is a balloon-borne soft gamma-ray (0.2 to 5 MeV) telescope designed to perform wide-field imaging, high-resolution spectroscopy, and novel polarization measurements of astrophysical sources. COSI employs a compact Compton telescope design, utilizing 12 cross-strip germanium detectors to track the trajectory of incident photons, where position and energy deposits from Compton interactions allow for a reconstruction of the source sky position, an inherent measure of the linear polarization, and significant background reduction. COSI was launched from the Long Duration Balloon site near McMurdo Station, Antarctica, in December 2014 where the primary science goal was to measure gamma-ray burst polarizations; however, the flight was cut unexpectedly short due to a leak in the balloon. We will present instrument calibrations of the energy and 3D-position of interactions within the detector that were taken in preparation for the 2014 campaign. We will discuss the integrated instrument and system testing to determine the angular resolution and detector efficiency, for comparison to simulations.