Dosimetry and Calorimetry Performance of a Scientific CMOS Camera for Environmental Monitoring

• Published in: Sensors (Basel, Switzerland) Switzerland), 2020-10, Vol.20 (20), p.5746
• Main Authors: Aguilar-Arevalo, Alexis, Bertou, Xavier, Canet, Carles, Cruz-Pérez, Miguel Angel, Deisting, Alexander, Dias, Adriana, D’Olivo, Juan Carlos, Favela-Pérez, Francisco, Garcés, Estela A., González Muñoz, Adiv, Guerra-Pulido, Jaime Octavio, Mancera-Alejandrez, Javier, Marín-Lámbarri, Daniel José, Martinez Montero, Mauricio, Monroe, Jocelyn, Paling, Sean, Peeters, Simon J. M., Scovell, Paul, Türkoğlu, Cenk, Vázquez-Jáuregui, Eric, Walding, Joseph
• Format: Article
• Language: English
• Subjects: Atoms & subatomic particles; Cameras; Charged particles; CMOS; commercial CMOS cameras; Dosimeters; Dosimetry; Drinking water; Energy; Energy resolution; Environmental monitoring; gamma detection; Gamma rays; Heat measurement; lead in drinking water; Lead isotopes; lead-210; Low income groups; Noise; Radiation; Radioisotopes; scientific CMOS sensor; Sensitivity analysis; Sensors; Silicon; Water supply; X ray detectors; X-ray detection; X-rays
• ISSN: 1424-8220; 1424-8220
• DOI: 10.3390/s20205746

This paper explores the prospect of CMOS devices to assay lead in drinking water, using calorimetry. Lead occurs together with traces of radioisotopes, e.g., 210Pb, producing γ-emissions with energies ranging from 10 keV to several 100 keV when they decay; this range is detectable in silicon sensors. In this paper we test a CMOS camera (Oxford Instruments Neo 5.5) for its general performance as a detector of X-rays and low energy γ-rays and assess its sensitivity relative to the World Health Organization upper limit on lead in drinking water. Energies from 6 keV to 60 keV are examined. The CMOS camera has a linear energy response over this range and its energy resolution is for the most part slightly better than 2%. The Neo sCMOS is not sensitive to X-rays with energies below ∼10 keV. The smallest detectable rate is 40±3mHz, corresponding to an incident activity on the chip of 7±4Bq. The estimation of the incident activity sensitivity from the detected activity relies on geometric acceptance and the measured efficiency vs. energy. We report the efficiency measurement, which is 0.08(2)% (0.0011(2)%) at 26.3keV (59.5keV). Taking calorimetric information into account we measure a minimal detectable rate of 4±1mHz (1.5±1mHz) for 26.3keV (59.5keV) γ-rays, which corresponds to an incident activity of 1.0±6Bq (57±33Bq). Toy Monte Carlo and Geant4 simulations agree with these results. These results show this CMOS sensor is well-suited as a γ- and X-ray detector with sensitivity at the few to 100 ppb level for 210Pb in a sample.