Abstract
The central neutron spectrum of the Big Ten Critical Assembly, a cylindrical assembly with a 10% enriched uranium metal core surrounded by a depleted uranium metal reflector, has been measured between 32 keV and 1177 keV, using proton recoil proportional counting techniques. A cylindrical detector filled with hydrogen gas was used for measurements between 23 keV and 650 keV, and a methane filled detector was used between 228 keV and 2.6 MeV. Pulse shape discrimination techniques were used to separate proton recoil pulses from electron pulses resulting from [gamma] -ray interactions below 200 keV. All of the measurements were performed with the assembly at a reactivity of 37 cents below delayed critical. The neutron spectrum was determined from the recoil proton data by response function unfolding. The monoenergetic neutron response functions and the high energy corrections to the data were computed using Monte Carlo methods. Monoenergetic neutron measurements were carried out at the LASL high current Van De Graaff and the Cockcroft-Walton Accelerator in order to test the accuracy of the computed response functions. The results of the spectrum measurements are compared with a transport theory computation of the neutron spectrum using E.N.D.F./B-III cross-section sets.
Lozito, Edward Joseph (1974). The measeurement of the neutron spectrum of a fast critical assembly using proton recoil proportional counting. Doctoral dissertation, Texas A&M University. Texas A&M University. Libraries. Available electronically from
https : / /hdl .handle .net /1969 .1 /DISSERTATIONS -171909.