Calibration and characterization of the neutron spectrometer onboard the Weiming-1 CubeSat

For the measurement of neutron flux in the complex radiation environment of low Earth orbit (LEO), a neutron spectrometer (NS) incorporating background suppression techniques was constructed and launched on board the “Weiming-1” CubeSat in January 2024. The NS is based on silicon solid-state detectors with a high anti-coincidence efficiency for background charged particles, which may enhance the precision of neutron flux quantification. This study comprehensively details the energy calibration, efficiency calibration, and stability test of the NS, through a series of controlled particle sources, including monoenergetic fast neutron beams, a thermal neutron field, and gamma-ray radioactive sources. The experimental results are well reproduced by Geant4 simulation. Unfolding results of monoenergetic neutron spectra and preliminary analysis of on-orbit data are presented as well.