Neutron spectra around a tandem linear accelerator in the generation of 18F with a bonner sphere spectrometer

Abstract

A Bonner sphere spectrometer was used to measure the neutron spectra produced at the collision of protons with an H218O target at different angles. A unique H218O target to produce 18F was designed and placed in a Tandem linear particle accelerator which produces 8.5MeV protons.The neutron count rates measured with the Bonner spheres were unfolded with the MAXED code. With the GEANT4 Monte Carlo code the neutron spectrum induced in the (p, n) reaction was estimated, this spectrum was used as initial guess during unfolding. Although the cross section of the reaction 18O(p,n)18F is well known, the neutron energy spectra is not correctly defined and it is necessary to verify the simulation with measurements. For this reason, the sensitivity of the unfolding method to the initial spectrum was analyzed applying small variation to the fast neutron peak.