ASNR neutron spectrometry campaigns at Bondeno

SoMMet partner ASNR (Autorité de sûreté nucléaire et de radioprotection—the French Nuclear Safety and Radiation Protection Authority) conducted two neutron spectrometry campaigns at the Bondeno test field site in northern Italy, from 31 March to 5 April and from 10 to 14 June 2025.

ASNR deployed nine detectors from its HERMEIS extended-range Bonner sphere spectrometer. By combining measurements from moderating spheres of different sizes and materials, this system can reconstruct the environmental neutron energy spectrum over a broad energy range. The measurements provided reference data for investigating and interpreting cosmic-ray neutron sensing (CRNS) under outdoor conditions.

Strong wind and rain affected the first campaign, resulting in increased noise and limited counting statistics. The measurements were therefore repeated under more favourable weather conditions in June, producing a higher-quality dataset. These data were also used for comparison with the W-PIE neutron spectrometer and for benchmarking simulations performed using the URANOS neutron-transport model.

Further details about the measurement setup, data analysis and results are provided in SoMMet Deliverable D3.