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241 Am-Be source abstract A measurement campaign has been carried out recently to provide the source intensity and the reference spectra around a neutron irradiation facility based on 241 Am-Be radionuclide source, using the UAB Bonner Sphere Spectrometer. This facility, which consists of a bunker, a container/shielding for the source and an irradiation device that uses an automated remote-controlled system for the source positioning and rotating during the dosimeter irradiation, is intended to be routinely used to check the response of passive dosimeters, namely those based on photo-stimulated imaging plates and solid-state nuclear track detectors. The measurement results, in terms of neutron spectra and global dosimetric quantities (i.e., fluence and ambient dose equivalent rates) at different distances with respect to the 241 Am-Be source, were compared with Monte Carlo simulations using the MCNPX code and a good agreement was observed. An estimation of the un-scattered neutron spectrum directly emitted from the 241 Am-Be source is given as well.

The RaMsEs group (Radioprotection et Mesures Environnementales) is working on a new compact device for operational neutron dosimetry. The electronic part of the detector is made of an integrated active pixel sensor, originally designed for tracking in particle physics. This device has useful features, including a high detection efficiency for charged particles, a good radiation resistance, a high readout speed and a low power consumption. Moreover, because of the thinness of the active layer, these CMOS sensors have low sensitivity to γ - rays , which is an attractive feature for neutron issues. In order to determine the γ response of the sensor, measurements have been carried out with a γ source of 60Co (1.17 MeV and 1.33 MeV). Other experiments have been performed with a fast neutron source of AmBe. We demonstrate the good discrimination between recoil protons from fast neutrons and from γ - background . Our results show that with an appropriate threshold, most γ - rays that generate photoelectrons can be removed from detection.

International audience; Polyallyl diglycol carbonate can be polymerized to make solid-state nuclear track detectors, type PN3, that are widely used for neutron dosimetry. Neutrons are detected by the damage trails created by recoil nuclei of the PN3 constituent atoms that are subsequently revealed by either a suitable chemical etching (CE) or electrochemical etching (ECE) process. On the basis of calibration exposures, track density can be related to neutron dose equivalent. The dose equivalent response and the detection level depend on detector material, nature and thickness of the radiator, energy and angle of incidence of the neutron, and the etching process. An automated ECE and reading system has been developed in RaMsEs laboratory. We compare the PN3 neutron dose equivalent response to 241Am–Be neutrons without radiator for both CE and ECE

We describe a fully standalone compact electronic monitor for atmospheric 222 Rn, based on a new CMOS system-on-chip. The electronic board consists of three AlphaRad CMOS chips running in parallel, and it includes a numeric block for data treatment based on a Xilinx programmable gate array. In addition to classical tests (passive detection in a calibrated radon chamber), we present the first results with active collection of radon progeny present as aerosols.

International audience; 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 241Am–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

A CMOS active pixel sensor, originally designed for the tracking of minimum ionizing particles in high energy physics, has been recently used for the detection of fast neutrons. Data were taken at the French neutron reference facility (IRSN, Cadarache) with an Am-Be source and a polyethylene radiator. A high intrinsic efficiency ( 1.6 × 10 - 3 ) has been obtained, which is compatible with results from calculations and Monte Carlo simulations. This experiment paves the way for a fully electronic personal neutron dosemeter.

The development of pixel CMOS sensors for particle tracking in high energy physics has led to promising applications for dosimetry. We present the last results in electronic monitoring of atmospheric radon with the new system-on-chip AlphaRad, as well as highly efficient detection of fast neutrons with a megapixel Active Pixel Sensor of the MIMOSA generation.