Neutrons spectrometry by threshold detectors method and interpretation using transport theory

The transport theory and the unfolding neutron spectra method using threshold detectors were studied and applied to determine the neutron spectrum that arose from transport through a paraffin cylinder of 14 Mev neutrons produced by the T (d,n) a reaction. The treatment of the residual nucleus saturated activities was carried out using the SAND 2 and WINDOWS unfolding spectra codes. A comparison of about fifteen neutron cross section libraries was carried out, too and allowed for recommending the most accurate ones for use in neutron dosimetry. The analysis of the results obtained from SAND 2 and WINDOWS showed that the SAND 2 code is more adequate for such a purpose. The utilization of the ANISN-E and the DOT-3.5/E codes that solve the transport equation by the discrete ordinates method allowed for computing both neutron energy spectra and the spatial distributions in the paraffin cylinder of the uncollided, fast, intermediate, thermal and total neutron fluxes. The comparison of the results of these two codes showed that the use of a simple model of one dimension (ANISN-E) is sufficient for computing the initial spectrum approximation the knowledge of which is necessary in the unfolding spectra method. (author). 40 refs.; 39 figs.; 12 tabs