Neutron Energy Deposition Spectra at Simulated Diameters Down to 50 nm

A special cylindrical tissue-equivalent proportional counter has been designed and constructed. Using a recently developed calibration technique with 37Ar, its performance has been analysed for simulated sites with diameters down to 100 nm. Neutron energy deposition spectra have been obtained for simulated diameters 50-2000 nm with neutron beams from the 2H(d,n)3He reaction. The peak at high energies imparted due to heavy particle recoils and the proton edge are clearly seen in the spectra even at the smallest simulated diameters.