Effective Macroscopic Cross Section Research Articles

Drying of Kaolin Clay Cylinders: Dynamic Neutron Radiography Studies

The results of the dynamic neutron radiography studies on drying of wet kaolin cylinders in the forced warm air flow are presented. The sample shrinkage and loss of water during drying was analyzed in terms of the brightness of registered neutron radiographs, and sample mass and temperature. The water saturation of the sample with water was discussed in comparison to the changes in local neutron effective macroscopic cross section. The neutron radiography results reveal more details of the drying process than gravimetric measurements indicating nonuniform distribution of water within samples. The obscuring effect of the scattered neutrons on the determination of the water content is discussed on the basis of the MC simulations results.

An improved fast neutron radiography quantitative measurement method

The validity of a fast neutron radiography quantification method, the Σ-scaling method, which was originally proposed for thermal neutron radiography was examined with Monte Carlo calculations and experiments conducted at the YAYOI fast neutron source reactor. Water and copper were selected as comparative samples for a thermal neutron radiography case and a dense object, respectively. Although different characteristics on effective macroscopic cross-sections were implied by the simulation, the Σ-scaled experimental results with the fission neutron spectrum cross-sections were well fitted to the measurements for both the water and copper samples. This indicates that the Σ-scaling method could be successfully adopted for quantitative measurements in fast neutron radiography.

An improved fast neutron radiography quantitative measurement method

The validity of a fast neutron radiography quantification method, the Σ-scaling method, which was originally proposed for thermal neutron radiography was examined with Monte Carlo calculations and experiments conducted at the YAYOI fast neutron source reactor. Water and copper were selected as comparative samples for a thermal neutron radiography case and a dense object, respectively. Although different characteristics on effective macroscopic cross-sections were implied by the simulation, the Σ-scaled experimental results with the fission neutron spectrum cross-sections were well fitted to the measurements for both the water and copper samples. This indicates that the Σ-scaling method could be successfully adopted for quantitative measurements in fast neutron radiography.

Observed Penetration of 14-MeV Neutrons in Various Materials

Experimentally observed 14-MeV neutron removal cross sections are presented for 16 materials. At a scattering energy loss of 4MeV, the effective macroscopic cross section per unit mass (in square centimeters per gram) for a nucleus of mass A is given by 0.25A[sup [minus]1.78] + 0.10A[sup [minus]0.47]. Such information provides a simple method for estimating neutron transport in systems driven by thermonuclear neutrons.