Jean-Christophe Bilheux

Evaluation of segregation in Roman sestertius coins

Three brass sestertius coins from the reign of Gordian III were imaged at the Oak Ridge National Laboratory’s neutron imaging beam, CG-1D, at the High Flux Isotope Reactor. Tomography results showed a gradual variation in neutron attenuation from one side of the coins to the other or toward the center of the coin. Linear neutron attenuation values calculated from the neutron radiographs, as well as micro-XRF results, suggest that this gradual variation in neutron attenuation is associated with elemental segregation within the coins. The difference in segregation patterns between the coins implies two types of casting methods were utilized to form the coins—vertical and horizontal casting methods.

Applying neutron transmission physics and 3D statistical full-field model to understand 2D Bragg-edge imaging

Bragg-edge imaging, which is also known as neutron radiography, has recently emerged as a novel crystalline characterization technique. Modelling of this novel technique by incorporating various features of the underlying microstructure (including the crystallographic texture, the morphological texture, and the grain size) of the material remains a subject of considerable research and development. In this paper, Inconel 718 samples made by additive manufacturing were investigated by neutron diffraction and neutron radiography techniques. The specimen features strong morphological and crystallographic textures and a highly heterogeneous microstructure. A 3D statistical full-field model is introduced by taking details of the microstructure into account to understand the experimental neutron radiography results. The Bragg-edge imaging and the total cross section were calculated based on the neutron transmission physics. A good match was obtained between the model predictions and experimental results at diffe...

The CARDS array for neutron-rich decay spectroscopy at HRIBF

An array for decay studies of neutron-rich nuclei has been commissioned for use at the UNISOR separator at Holifield Radioactive Ion Beam Facility. This array consists of three segmented clover Ge detectors, plastic scintillators, and a high-resolution (∼1 keV) Si conversion electron spectrometer. These detectors are mounted on a support that surrounds a moving tape collector. This system has been named clover array for radioactive decay studies. The detectors have been outfitted with digital flash ADCs (XIA DGFs) that fit the preamp signals, with built-in pileup rejection.

The Use and Refinement of Neutron Imaging Techniques for Archaeological Artifacts

Abstract Neutron imaging is a nondestructive application capable of producing two- and three-dimensional maps of archaeological objects’ external and internal structure, properties, and composition. This report presents the recent development of neutron imaging data collection and processing methods at Oak Ridge National Laboratory (ORNL), which have been advanced, in part, by information gathered from the experimental imaging of 25 archaeological objects over the past three years. The dual objectives of these imaging experiments included (1) establishing the first methodological procedures for the neutron imaging of archaeomaterials involving the CG-1D beamline and (2) further illustrating the potential of neutron imaging for archaeologists to use in the reverse engineering of ancient and historical objects. Examples of objects imaged in two and three dimensions are provided to highlight the application’s strengths and limitations for archaeological investigations, especially those that address ancient and historic technologies, materials science, and conservation issues.

Large-Scale User Facility Imaging and Scattering Techniques to Facilitate Basic Medical Research

Conceptually, modern medical imaging can be traced back to the late 1960’s and into the early 1970’s with the advent of computed tomography1. This pioneering work was done by 1979 Nobel Prize winners Godfrey Hounsfield and Allan McLeod Cormack which evolved into the first prototype Computed Tomography (CT) scanner in 1971 and became commercially available in 1972. Unique to the CT scanner was the ability to utilize X-ray projections taken at regular angular increments from which reconstructed three-dimensional (3D) images could be produced. It is interesting to note that the mathematics to realize tomographic images were developed in 1917 by the Austrian mathematician Johann Radon who produced the mathematical relationships to derive 3D images from projections – known today as the Radon Transform2. The confluence of newly advancing technologies, particularly in the areas of detectors, X-ray tubes, and computers combined with the earlier derived mathematical concepts ushered in a new era in diagnostic medicine via medical imaging (Beckmann, 2006).

Collective and noncollective states in Cd-116 studied via the beta decays of Ag-116m1, m2, gs

We have re-investigated the beta decay of the three isomers of

Collective and Non-Collective States in 116Cd Studied via the Beta-Decays of 116Agm1,m2,gs

^{116}

A universal method for effusive-flow characterization of target/vapor transport systems for RIB generation

Ag at the Holifield Radioactive Ion Beam Facility (HRIBF). Through the use of half-life information, we have been able to construct individual decay schemes for each isomer, and correct what was a puzzling inconsistency with the published data, namely the beta feeding of 2