10B enriched film deposited by e-beam technique on Al2O3 substrate for high efficiency thermal neutron detector

•10B-enriched film characterizations for 3He-free neutron detectors are reported.•B content as high as 78% and 1 μm thick films were deposited on Al2O3 substrates.•B films revealed no delamination and high film adhesion.•Measured neutron detection efficiency was in agreement with the expectations.•Results are encouraging in perspective of 3He-free neutron detector development.

In the framework of the research and development activity on He-free neutron detection systems, the solid state physics experimental techniques and characterization tools can provide a valuable contribution for detector assessment and performance improvement. Presently, a He-replacement strategy relies on the use of Li-and/or B-based neutron to charge particle converters coupled to particle detectors (solid state, gaseous, scintillators). In particular, in this paper the detailed structural and chemical–physical characterization of 10B-enriched films deposited by e-beam evaporation onto alumina substrates is reported. X-ray diffraction and photoelectron spectroscopy investigations have revealed that high B content (about 78%) can be achieved on these films, contaminants being mainly C and O most likely coming from the B targets. Microstructural investigation carried out by AFM, SEM and nanoindentation techniques have mainly revealed that B films replicated the alumina substrate microstructural features. The described 10B/Al2O3 samples were successfully tested in a Gas Electron Multiplier based neutron detector with measured detection efficiency in full agreement with the expectations.