The Ionospheric Neutron Content Analyzer (INCA) is a double scatter neutron spectrometer designed for a 3U CubeSat, currently set for an Educational Launch of Nanosatellites (ELaNa)
launch in 2019. In a double scatter neutron spectrometer, a neutron scatters in two separate scintillators (D1, D2) spaced 15 cm apart, giving information on the incident neutron’s direction and energy from the pulse height in D1 and time-of-flight between the scintillators. INCA employs silicon photomultiplier (SiPM) arrays coupled to p-terphenyl scintillators. A neutron scattering event in p-terphenyl results in a pulse shape with a longer tail, due to delayed fluorescence of the scintillator, than that of a gamma ray. This property, known as pulse shape discrimination, is utilized in INCA to distinguish detected neutrons from gamma rays. Charged particles are vetoed by plastic scintillator anticoincidence detectors completely surrounding the spectrometer. The instrument was calibrated using a 252Cf neutron beam, and compared to Geant4 simulation results. Details of the INCA instrument and these calibrations are discussed.