Beamtime at PTB neutron facility

Different types of CRNS (cosmic-ray neutron sensing) sensors were characterised at the PTB Ion Accelerator Facility (PIAF) in the week from 12 to 16 February 2024. In the natural environment, the CRNS sensors are used to monitor the dynamics (changes) of soil moisture via continuous measurement of naturally occurring neutrons. In the laboratory, "artificial" neutrons with well-defined energies are created based on various nuclear reactions. In neutron metrology, these so-called neutron reference fields are typically used for calibrating or characterising various neutron-sensitive instruments (such as neutron spectrometers, detectors, monitors, personal dosimeters). During our beamtime at PTB, the CRNS sensors were irradiated in well-known neutron reference fields that are SI-traceable to standards of neutron metrology. This way we establish the metrological basis for the CRNS methodology, by improving the understanding of the sensors' sensitivity to neutrons and performance under laboratory conditions. In next steps, the performance under outdoor conditions will be systematically researched as well.