Development of a new electronic personal neutron dosemeter using a CMOS active pixel sensor

Abstract

A CMOS active pixel sensor, originally designed for the tracking of minimum ionising charged particles in high-energy physics, has been recently used for the detection of fast neutrons. Data were taken at the IRSN Cadarache facility with a (241)Am-Be ISO source and a polyethylene radiator. A high-intrinsic efficiency (1.2 x 10(-3)) has been obtained. It is in good agreement with both calculations and a MCNPX Monte Carlo simulation. This experiment paves the way for a fully electronic personal neutron dosemeter.

Development of an integrated CMOS detector for radon activity measurement and neutron dosimetry

“…Straggling: At these energies, the elastic (n,p) diffusion is isotropic in the center-of-mass, and simulation indicates that the mean diffusion angle of the protons is 27 • (from the neutron trajectory). Indeed, we could observe some isolated proton tracks at large angles, crossing in this case several adjacent pixels [5]. The cumulated detected charge follows a Landau distribution (straggling), as expected from MeV protons loosing energy a thin silicon layer ( fig.…”

“…Diffusion cross-section values and proton range calculations (in (CH 2 ) n , air, SiO 2 and Si) show that only the last 85 µm of the polyethylene radiator can contribute to detectable protons, which must have a minimal energy of 950 keV to reach the sensitive volume [5]. From these considerations, the expected efficiency of our system (in the AmBe spectrum) should be of about 1.1 × 10 −3 p/n.…”

“…From these considerations, the expected efficiency of our system (in the AmBe spectrum) should be of about 1.1 × 10 −3 p/n. A more detailed Monte Carlo calculation with the MCNPX code leads again to ε MC = 1.1 × 10 −3 n/p [5]. Both calculations do not take into account inelastic reactions inside the detector itself (SiO 2 and Si) and the surrounding Al box.…”

A new compact device for efficient neutron counting using a CMOS active pixel sensor

“…The shape of this cluster resembles the Bragg stopping curve which results when a proton loses all its energy in the epitaxial layer. This event must come from a scattered neutron (Trocmé et al, 2007).…”

R&D métrologie des rayonnements ionisants à l’IPHC : de l’application des détecteurs visuels aux mesures environnementales

“…La problématique de la dosimétrie des neutrons est en pleine évolution, sous la pression de nouvelles normes européennes et dans le contexte très sensible des programmes de démantèlement massifs dans l'industrie du nucléaire civil. Pour cette problématique, des tests préliminaires complétés par des simulations Monte-Carlo (GEANT4 et MCNPX) sont en cours de réalisation pour l'étude de la fonction de réponse et de l'efficacité de détection neutron (Trocmé et al, 2007). Nous projetons d'étudier la sensibilité du système à deux gammes d'énergie, les neutrons rapides pouvant être convertis en protons via un convertisseur hydrogéné, les neutrons thermiques convertis en particules alpha.…”