Balloon flight results of a FAst compton telescope (FACTEL)

Current medium energy gamma-ray astronomy is limited by the intense atmospheric or local background radiation degrading the sensitivity of instruments. Compton Telescopes´ background rejection capabilities can be significantly improved with no loss of effective area by narrowing as much as possible the event acceptance Time of Flight (ToF) window by using fast scintillators materials such as LaBr₃. We present the balloon test flight results of the FAst Compton TELescope (FACTEL) prototype we built using LaBr₃ scintillators, along with other techniques to reduce the neutron induced background. This 26 hour flight from NASA´s Columbia Scientific Balloon Facility at Fort Sumner, New Mexico, permitted us to evaluate the background rejection capabilities offered by our 1.2 ns ToF window compared to COMPTEL´s 4 ns. We also report laboratory and Monte Carlo simulations results. We use these results to make a preliminary evaluation of the performance of a larger future instrument based on similar principles.