Spectroscopic Compton Imaging of Prompt Gamma Emission at the MeV Energy Range

Published

October 1, 2018

Author(s)

Haijian Chen, Heather H. Chen-Mayer, Danyal J. Turkoglu, Benjamin Riley, Emily Draeger, jerimy Polf

Abstract

Prompt gamma activation analysis (PGAA) is a bulk elemental analysis technique using gamma rays emitted immediately following neutron capture. Spatial information about the composition within the sample could be obtained with PGAA in a time-consuming process by physically scanning the sample with either a collimated or focused neutron beam and/or by restricting the angle subtended by the gamma ray detector. This work explores a novel tomographic approach to PGAA that is both quantitative and spatially resolved. The method is adapted from a "proton beam range finder" developed for a radiotherapy clinical setting in which MeV gammas rays are imaged by coincidence measurements of Compton scattered gamma rays with multi-detector arrays. The coincident events are reconstructed to obtain 3-dimensional (3D) information of the origin of the gamma ray emission with millimeter resolutions. We performed preliminary measurements using the PGAA facility at the NIST Center for Neutron Research using a Compton camera made with CdZnTe detector arrays on a series of test samples (NaCl, Ti, and wax disks) with high- energy (> 1 MeV) gamma emission lines. The measured spectra were used to assess the energy resolution and sensitivity (count rate per unit mass) of the camera. 3D image reconstructions were performed on selected emission peak at 2.2 MeV by H. The reconstructed image intensity varies linearly as a function of sample mass and can be calibrated against the sensitivity obtained from the spectral analysis. The image reconstruction methods were also evaluated using the emission data generated by Monte Carlo simulations, demonstrating a simplistic 3D elemental map is achievable under ideal conditions.

Citation

Journal of Radioanalytical Nuclear Chemistry

Pub Type

Journals

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DOI Link

Keywords

Compton imaging, Prompt gamma activation analysis, 3D elemental distribution

Citation

Chen, H. , Chen-Mayer, H. , Turkoglu, D. , Riley, B. , Draeger, E. and Polf, J. (2018), Spectroscopic Compton Imaging of Prompt Gamma Emission at the MeV Energy Range, Journal of Radioanalytical Nuclear Chemistry, [online], https://doi.org/10.1007/s10967-018-6070-3 (Accessed October 25, 2024)