High spatial resolution neutron detection based on CMOS image sensors

M. PEREZ; J. LIPOVETZKY; E. MARTINEZ; O. INTI ABBATE; F. ALCALDE; M. SOFO HARO; J. MARIN; F. SANCHEZ; J. LONGHINO; M. GÓMEZ; J. BLOSTEIN

Buenos Aires

Conferencia; International Conference on Neutron Scattering; 2022

We present two novel high spatial resolution neutron detection techniques based on CMOSimage sensors (CIS). Firstly, we introduce a thermal neutron detector implemented with aCIS and a conversion layer made of sodium gadolinium fluoride (NaGdF 4 ) nanoparticles. Inthis case, the images are obtained by the detection of electrons emitted by the Gd present inthe conversion layer. A production method of test patterns made on neutron-absorbingmaterials by optical lithography and chemical etching is detailed. These patterns wereemployed to evaluate the performance of the implemented technique. After experimentsperformed at the RA6 Nuclear Research Reactor (Bariloche, Argentina) we have obtainedthe first neutron images. The achieved intrinsic spatial resolution is better than (15±6) μm.This upper bound is comparable with that of the best neutron position-sensitive detectorsavailable nowadays. This neutron detection technique was tested in neutron imagingexperiments, and also has potential applications in the characterization of neutron beamprofiles, as well as in diverse experimental techniques based on the use of neutron beams,for example small angle neutron scattering, neutron reflectometry, neutron diffraction,neutron transmission, among several others. Secondly, we present a neutron radiographymethod in which the images are obtained through the activation of an Indium foil, and thesubsequent off-line detection of the electrons emitted by the Indium beta decay. Thisdetection method has been designed for the acquisition of thermal and epithermal neutronimages at mixed beams with a high gamma flux. It can be used to study samples placed intoresearch reactor pools, for example nuclear fuel and structural components of nuclearresearch reactors. Measurements performed in a neutron beam of the RA6 reactor, confirmthe capability of the proposed technique.