Neutron Diffusion Parameters Research Articles

Thermalization and Diffusion Parameters of Neutrons in Zirconium Hydride

The pulsed-source method is used to measure the thermal neutron diffusion parameters of Zircaloy-2 hydride, whose approximate composition is ZrH/ sub 1.7/. The asymptotic decay constant (zeroth energy eigenvalue) is measured for the buckling range 0.03 < B/sup 2/ < 0.39 cm/sup -2/ and is fitted by a polynomral containing terms to Bsup 8/. The first energy eigenvalue is measured over the range 0.05 < B/sup 2/ < 0.39 cm/sup 2/ and is used to estimate the thermalization time constant. In additron, the thermalization time constant is also determined from time-dependent transmission measurements wrth l/v absorbers. (auth)

Measurement of Neutron Diffusion Parameters in Water by the Pulsed Neutron Method

Neutron diffusion parameters in water were measured at 26.7 deg C with the pulsed neutron technique. The results are 210 plus or minus 1 mu sec for the neutron mean lifetime, 37503 plus or minus 366 cm/sup 2/ sec/sup -1/ for the average diffusion coefflcient, and 5116 plus or minus 776 cm/sup 4/ sec/sup - 1/ for the diffusion cooling constant. From these values the thermal absorption cross sectlon of hydrogen and the thermal diffusion length in water can be lnferred to be 325 plus or minus 2 mb and 2.83 plus or minus 0.02 cm, respectively. With a pulsed high-intensity neutron source provided by an electron linear accelerator, neutron lifetime measurements were performed on small and large water samples wlth values of the geometrlcal buckling from 0.014 cm/sup -2/ to 0.59 cm/sup -2/. Effects of harmonic modes in the large water geometrles, whlch were determined by measurements of the time-dependent spatial flux distributlons resulting from an external pulsed source of fast neutrons, were found to be adequately predictable with slmple diffuslon theory. (auth)

Neutron Diffusion in Small Volumes of Water: Pulsed Source Measurements

The thermal neutron diffusion parameters for light water have been measured using the pulsed neutron source technique. It has been demonstrated that the value of the diffusion cooling coefficient is critically dependent on the physical shape of the experimental system. The experimental results have been analysed using two different values of the extrapolation length, since the value of this parameter is not accurately known. The discrepancies between previously published values of the diffusion parameters are largely explained by their dependence on system shape and extrapolation length.

Measurements of the Temperature Dependence of Thermal Neutron Diffusion Parameters in Water and Dowtherm A

"Measurements of the Temperature Dependence of Thermal Neutron Diffusion Parameters in Water and Dowtherm A." Nuclear Science and Engineering, 8(1), p. 88