Evaluation of the next generation gamma imager

K. Amgarou (1) , T. Timi (1) , N.B. de Lanaute (1) , Frédérick Carrel (2) , Vincent Schoepff (2) , Hermine Lemaire (2) , Mehdi Gmar (3) , R. Abou Khalil (4) , S. Dogny (4) , T. Varet (4) , A. Patoz (1) , P. Talent (1) , N. Menaa (1)

1 CANBERRA France
2 LCAE (CEA, LIST) - Laboratoire Capteurs et Architectures Electroniques (CEA, LIST)
3 LM2S (CEA, LIST) - Laboratoire Modélisation et Simulation de Systèmes (CEA, LIST)
4 Groupe AREVA

Towards the end of their life-cycle, nuclear facilities are generally associated with high levels of radiation exposure. The implementation of the ALARA principle requires limiting the radiation exposure of the operating people during the different tasks of maintenance, decontamination and decommissioning. CANBERRA's latest involvement in the provision of nuclear measurement solutions has led, in the framework of a technology transfer agreement with CEA LIST, to the development of a new generation gamma imager. The latter, which is designed for an accurate localization of radioactive hotspots, consists of a pixilated chip hybridized to a 1 mm thick CdTe substrate to record photon pulses and a coded mask aperture allowing for background noise subtraction by means of a procedure called mask/anti-mask, which greatly contributes to the reduced size and weight of the gamma imager as gamma shielding around the detector is less required. The spatial radioactivity map is automatically superimposed onto a pre-recorded photographic (visible) image of the scene of interest. In an effort to evaluate the performances of the new gamma imager, several experimental tests have been performed on a industrial prototype to investigate its detection response, including photon sensitivity and angular resolution, over a wide energy range (at least from 59 keV to 1330 keV). The impact of the background noise was also evaluated together with some future features like energy discrimination and parallax correction. This paper presents and discusses the main results obtained in the above experimental study. A comparison with Monte Carlo simulations using the MCNP code is provided as well.

Mots clés: ALARA principle implementation; radiation exposure levels; next generation gamma imager evaluation; Gamma imaging; solid scintillation detector; instrumentation; nuclear instrumentation; radiation protection; radioactivity measurement; ionizing radiation; radioactivity; Detector; Camera; Apertures; Prototype; Image resolution; gamma-ray detection; gamma-rays; nuclear measurement solutions; radioactive hotspots; pixilated chip hybridization; CdTe substrate; background noise subtraction; gamma shielding; spatial radioactivity map; gamma-ray detection response; energy discrimination; parallax correction; Monte Carlo; simulation; MCNP code; coded mask aperture; CMOS pixilated readout chip

Domaines: Physique Nucléaire Expérimentale [nucl-ex]; Instrumentations et Détecteurs [physics.ins-det]; Traitement du signal et de l'image [eess.SP]; Modélisation et simulation

K. Amgarou, T. Timi, N.B. de Lanaute, Frédérick Carrel, Vincent Schoepff, et al.. Evaluation of the next generation gamma imager. ANIMMA2013 - 3rd International Conference on Advancements in Nuclear Instrumentation, Measurement Methods and their Applications, Jun 2013, Marseille, France. ⟨10.1109/ANIMMA.2013.6728051⟩. ⟨cea-01822343⟩