CHARACTERIZATION OF THE SOURCE NEUTRONS PRODUCED BY THE FRASCATI NEUTRON GENERATOR

Integral experiments with a neutron source based on the T(d,n)alpha re action require a good knowledge of the source neutron distribution. Th e source neutrons are energy-angle distributed with an energy spread o f a few mega-electron-volts and anisotropy emission of a few percent. The characterization of the 14-MeV neutron source of the Frascati Neut ron Generator (FNG) has been carried out using an absolutely calibrate d U-Nat microfission chamber with plane electrodes and Nb-93(n,2n)Nb-9 2m activation reaction. The reaction rates have been measured at diffe rent angles with respect to the beam direction. The experimental resul ts are compared with the corresponding quantities calculated by using a Monte Carlo code (MCNP) with an ''ad hoc'' source model. The calcula ted neutron emission reproduces the measured one satisfactorily well. Improvement of the source model used is discussed.