Evaluation of the photographic capabilities of a Compton Camera device using the GEANT4 simulation toolkit

Abstract. Imaging via ʸ backscattering techniques are suitable for non destructive and non invasive methods to determine the amount and distribution of matter in objects, and these are very advantageous techniques when the access to both sides of the sample, unlike in the transmission case, is not possible. A ʸ-backscattering device dubbed the Compton Camera, developed at GSI (Darmstadt, Germany), has been modified and studied at Grupo de Física Nuclear de la Universidad Nacional de Colombia (Bogotá, Colombia). The Compton Camera is based on the so called Gamma-ray Compton Backscattering (GCB) technique and it uses back-toback emission of two ʸ-rays, from positron annihilation, to construct a bi-dimensional image representing the density distribution of the sample in the field-of-view of the camera. The main objective of this work is to increase the understanding of the response of the Compton Camera, in particular its image-forming process, to strengthen the data analysis and to evaluate limitations of the actual device. In this work a state-of-the-art simulation of the camera is presented, using the Geant4 simulation toolkit. The simulation was validated through comparison with experimental results, also the contribution of single and multiple Compton scatterings to image-forming process was determined, time-of-flight of ʸ-rays before detection was quantifiled and some limitations of the technique were studied. In order to enhance the image quality some digital image processing methods were implemented, a theoretical model of backscattering intensity is presented, and possible improvements to the current experimental setup are suggested. The Compton Camera can be used with success to identify hidden objects behind metallic walls, to locate high density objects buried in sand and it is very useful on diagnosis of metallic surfaces. Furthermore, the camera can be used in the detection of anti-personnel landmines buried in farming soil. The simulated images and their comparison with the experimental ones suggest already methods to improve the present experimental setup aiming for the proposal of the next generation of the Compton Camera prototype.

• Autores: Flechas García, David Camilo
• Fecha de publicación: 2014
• Institución: Universidad Nacional de Colombia
• Repositorio: Universidad Nacional de Colombia
• Idioma: spa
• OAI Identifier: oai:repositorio.unal.edu.co:unal/75222
• Acceso en línea: https://repositorio.unal.edu.co/handle/unal/75222; http://bdigital.unal.edu.co/39740/
• Palabra clave: 51 Matemáticas / Mathematics; 53 Física / Physics; 62 Ingeniería y operaciones afines / Engineering; ʸ-backscattering; Compton camera; One-side imaging; Geant4; Retrodisersión ʸ; Imagenología por un costado; Cámara compton
• Rights: openAccess
• License: Atribución-NoComercial 4.0 Internacional