In order to study the source spectra at different energies a single crystal diamond (SCD) detector (a very high resolution fast neutron detector [Pillon et al. (2011)]) was positioned at 22 different angles in front of FNG neutron target using a step motor which can perform a 360° rotation in 2x104 steps. The angles investigated spam from -90° to 120°, in 10° angle step. A Monte Carlo simulation (bottom figure) was used in order to compare the predicted neutron spectra and fluxes using the ad hoc developed FNG source routine ([Čufar et al. (2016)]).
Comparison measured neutron spectra using only the 12C(n,α)9Be reaction in diamond with calculations. The deposited energy in the diamond (left figure) is converted to neutron energy adding the reaction Q (5.7 MeV):
Measured flux normalized to the associate a particle monitor. The two large deeps (left figure) are due to the cooling pipes perturbation:
[Čufar et al. (2016)] A. Čufar, I. Lengar, I. Kodeli, A. Milocco, P. Sauvan, S. Conroy, L. Snoj, Comparison of DT neutron production codes MCUNED, ENEA-JSI source subroutine and DDT, Fus. Eng. and Design 109-111, pp. 164-168 (2016), DOI: 10.1016/j.fusengdes.2016.03.036
[Pillon et al. (2011)] M. Pillon, M. Angelone, A. Krása, A. J. M. Plompen, P. Schillebeeckx, M.L. Sergi, Experimental response functions of a single-crystal diamond detector for 5–20.5 MeV neutrons, Nuc. Ins. and Meth. A 640(1), pp. 185-191 (2011), DOI: 10.1016/j.nima.2011.03.005