Characterizing nuclear materials hidden in lead containers by neutron-tomography-driven prompt gamma activation imaging (PGAI-NT)

Abstract

Laboratories worldwide develop Prompt Gamma Activation Analysis (PGAA) towards a position-sensitive technique. A full 3D element mapping with adequate resolution is possible, but limited to small objects due to constrains of experiment time and neutron flux. An alternative method is the combination of prompt gamma activation analysis and neutron imaging. Radiography, or even a full tomography on a complex sample, can be completed in an hour, and this often provides enough information to define regions of interest in the sample. The detailed element analysis by PGAA is then carried out only at these spots, saving a substantial beam time. This option is best used for samples consisting of a few homogeneous parts. The method is presented on a nuclear forensic application. The experiments are compared to the results from sophisticated Monte Carlo calculations.

Revealing hidden features of a Japanese articulated iron lobster via non-destructive local elemental analysis and 3D imaging

“…After mounting the object onto the computer-controlled xyz sample stage, dynamic neutron radiography was used as real-time visual feedback for sample positioning 9 . Four positions were selected for compositional analysis based on the contrasts observed in the XCT: an area for Solder type 1, near the limbs of the lobster (Pos 1), an area where both Solder types are assumed to be present (Pos 2), an area representing the wall material only (Pos 3), and a spot around the eyes, representing Solder type 2 (Pos 4).…”

“…Advanced composition and structure analysis techniques available at large-scale facilities, such as synchrotrons and neutron centres, are capable of characterizing such valuable artifacts nondestructively [1][2][3][4] . While optical photons and X-rays can penetrate a few (hundred) µm into metals 5 , neutrons and gamma rays have an information depth up to a few mm-cm 6 , so they offer either bulk representativity in case of homogeneous samples 7 or local concentrations relevant to an internal gauge volume for nonhomogeneous objects 8 , even if this volume element is inaccessible from outside 9,10,11,12 .…”

Non-destructive analysis of metals and alloys using prompt gamma activation analysis and complementary methods

“…To reduce the necessary beam time, a two-step approach can be applied. The desired parts are pre-selected with the help of neutron imaging, and then local PGAA measurements are performed [170] with adequate spatial resolution [169]. The combination of the simultanaeously used prompt gamma activation imaging (PGAI) and neutron tomography (NT) is known as PGAI-NT [171].…”