Measurement and Monte Carlo modelling of the JRC 241Am–Li(α,n) source spectrum

The neutron energy spectrum of the JRC 2 4 1 Am-Li(α,n) radionuclide source has been measured at the PTB in Germany using various spectrometry systems, such as Bonner spheres, proton recoil counters and NE213 liquid scintillators. The source photon spectrum has been measured and the neutron contamination due to traces of beryllium through the 9 Be(α,n) 1 2 C reaction has been determined. The effects associated with source encapsulation and the materials it contains have been investigated previously, using Monte Carlo simulations, the various structures seen in the spectra have been explained and the anisotropy of fluence distributions in 4π have been calculated and compared to measurements. These extensive high resolution spectrometry measurements have been coupled to Monte Carlo calculations to provide a realistic spectrum and new spectrum-averaged fluence-to-dose equivalent conversion coefficients for the actual 2 4 1 Am-Li source.