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The Nuclear Compton Telescope (NCT) is a balloon-borne gamma-ray telescope which uses cross-strip germanium detectors to study astrophysical sources of nuclear line emission. The compact design allows for wide-field imaging with excellent efficiency from 0.2–10 MeV. Moreover, the Compton imaging principle utilized by NCT provides polarimetric sensitivity above 200 keV. We conducted an extensive calibration campaign using radioactive sources prior to our flight from Ft. Sumner, New Mexico in Spring 2009. We present the results of our calibration of the effective area throughout NCT's field of view and compare them with Monte Carlo simulations using a detailed mass model. Additionally, we assess NCT's polarimetric capabilities with observations of a partially-polarized beam.

The Nuclear Compton Telescope (NCT) is a balloon-borne soft gamma-ray (0.2-10 MeV) telescope designed to study astrophysical sources of nuclear line emission and polarization. NCT consists of twelve high-purity germanium cross-strip detectors (GeDs) that measure both the position and energy of gamma-ray interactions. A 10-GeD version was flown on May 17-18 2009 from the Columbia Scientific Balloon Facility in Fort Sumner, NM, with a total flight duration of 38.5 hours. Here we summarize the instrument, the calibrations, the flight, and our preliminary science results.

The Nuclear Compton Telescope (NCT) is a balloon-borne soft gamma ray (0.2–10 MeV) telescope designed to study astrophysical sources of nuclear line emission and polarization. The heart of NCT is an array of 12 cross-strip germanium detectors, designed to provide 3D positions for each photon interaction with full 3D position resolution to < 2 mm3. Tracking individual interactions enables Compton imaging, effectively reduces background, and enables the measurement of polarization. The keys to Compton imaging with NCT's detectors are determining the energy deposited in the detector at each strip and tracking the gamma-ray photon interaction within the detector. The 3D positions are provided by the orthogonal X and Y strips, and by determining the interaction depth using the charge collection time difference (CTD) between the anode and cathode. Our preliminary calibrations of the energy and the 3D position of interactions have been completed as well as the verifications of imaging capabilities. Here we will present the techniques and results.