Flash radiography with 24 GeV/c protons

Abstract

The accuracy of density measurements and position resolution in flash (40 ns) radiography of thick objects with 24 Gev/c protons is investigated. A global model fit to step wedge data is shown to give a good description spanning the periodic table. The parameters obtained from the step wedge data are used to predict transmission through the French Test Object (FTO), a test object of nested spheres, to a precision better than 1%. Multiple trials have been used to show that the systematic errors are less than 2%. Absolute agreement between the average radiographic measurements of the density and the known density is 1%. Spatial resolution has been measured to be 200 μm at the center of the FTO. These data verify expectations of the benefits provided by high energy hadron radiography for thick objects.

Monte Carlo simulation and parameterized treatment on the effect of nuclear elastic scattering in high-energy proton radiography

“…angle-cut dependent value of the nuclear interaction length λ was assumed [6]. This result, while possibly functional, was not pleasing because of the addition of new parameters.…”

“…The effect of beam emittance on the transmission can be included in this Gaussian approximation by adding the additional contribution to the beam divergence referenced to the offset a, normalized to units of κ , in quadrature to the multiple scattering caused by the object [6,7]. This gives…”

“…Either of a pair of collimators, 1.2 m long right circular cylinders of tungsten, was located at the Fourier mid-plane of the lens. The collimators approximated multiple-scattering angle acceptance cuts of 6.68 mrad [6]. In order to do comparisons with experimental data, a set of step wedges was radiographed in the simulation with 24 GeV/c and 10 10 incident protons.…”

“…For full-scale hydrotest experiments or thick objects, the angular spread of the beam fraction that passes through the magnetic lens to form the image is dominated by multiple Coulomb scattering (MCS) in the radiographed object, but elastic proton-nucleon scattering in the object can also have a significant effect on the transmitted angular distribution [5,6].…”

New Developments in Proton Radiography at the Los Alamos Neutron Science Center (LANSCE)

“…Experiments preformed using 24 GeV protons provided by the Alternating Gradient Synchrotron (AGS) accelerator at Brookhaven Nation laboratory demonstrated all of the expected gains from pRad when compared to X-rays with a set of unclassified [4] and classified static objects [5]. The use of pRad for dynamic testing of surrogate nuclear weapon primaries is being pursued by both the Russian [3,6] and Chinese [7][8][9][10][11] weapons program but not by the United States.…”