Alcalde Bessia, F., D. Flandre, N. André, J. Irazoqui, M. Pérez, M. Gómez Berisso, and J. Lipovetzky. "Ultra Low Power Ionizing Dose Sensor Based on Complementary Fully Depleted MOS Transistors for Radiotherapy Application." IEEE Transactions on Nuclear Science (2019): 1.
Abstract: We evaluate the use of the thick buried oxide (BOX) of Fully Depleted Silicon-on-Insulator (FD-SOI) transistors for Total Ionizing Dose (TID) measurements in a radiotherapy application. The devices were fabricated with a custom process in UniversitC) Catholique de Louvain (UCL) which allows to make accumulation mode PMOS transistors and inversion mode NMOS transistors. We characterized the temperature behavior of these devices and the response under X-ray radiation produced by an Elekta radiotherapy linear accelerator, and compared the obtained dose sensitivity to other published works. Taking advantage of these devices, an ultra low power MOS ionizing dose sensor, or MOS dosimeter, with inherent temperature compensation is presented. This dosimeter achieved a sensitivity of 154 mV/Gy with a temperature error factor of 13 mGy/°C and a current consumption below 1 nA.
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Alcalde Bessia, F., D. Flandre, N. André, J. Irazoqui, M. Pérez, M. Gómez Berisso, and J. Lipovetzky. "Fully-Depleted SOI MOSFET Sensors in Accumulation Mode for Total Dose Measurement." In 2018 IEEE Nuclear Science Symposium and Medical Imaging Conference Proceedings (NSS/MIC), 1–3. 2018 IEEE Nuclear Science Symposium and Medical Imaging Conference Proceedings (NSS/MIC)., 2018.
Abstract: Fully Depleted Silicon-on-Insulator (FD-SOI) transistors fabricated with a custom process in Université Catholique de Louvain (UCL) were irradiated with X-rays using an Elekta Synergy radiotherapy linear accelerator. I-V curves of FD-SOI are sensitive to charges produced in the buried oxide (BOX) by ionizing radiation, so it is possible to use these devices as radiation dosimeters. In this work, we evaluated the use of thick BOX back-gate transistors for Total Ionizing Dose (TID) measurement using different bias conditions and we obtained a maximum sensitivity of 191 mV/Gy for devices operating in accumulation mode.
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Alcalde Bessia, F., M. Pérez, M. Sofo Haro, I. Sidelnik, J. J. Blostein, S. Suárez, P. Pérez, M. Gómez Berisso, and J. Lipovetzky. "Displacement Damage in CMOS Image Sensors After Thermal Neutron Irradiation." IEEE Transactions on Nuclear Science 65, no. 11 (2018): 2793–2801.
Abstract: In this paper, CMOS image sensors were exposed to thermal neutrons observing an increase in the dark signal of many pixels. The effect was found to be similar to the damage caused by alpha particles irradiation. Rutherford backscattering spectroscopy (RBS) and SIMNRA simulation were used to confirm that the sensors contain boron in the insulation layers. The damage produced by thermal neutrons is explained as displacement damage caused by alpha particles and lithium-7 ions in the silicon active volume of the sensors after boron-10 thermal neutron capture.
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Galimberti, C. L., F. Alcalde Bessia, M. Perez, M. Gómez Berisso, M. Sofo Haro, I. Sidelnik, J. J. Blostein, H. Asorey, and J. Lipovetzky. "A Low Cost Environmental Ionizing Radiation Detector Based on COTS CMOS Image Sensors." In 2018 IEEE Biennial Congress of Argentina (ARGENCON), 1–6. 2018 IEEE Biennial Congress of Argentina (ARGENCON)., 2018.
Abstract: We present the development of a system for the detection of ionizing radiation based on the Omnivision OV5647 Commercial Off The Shelf image sensor. The data is read and processed in real-time using a Raspberry Pi 3 computer. The amount of charge and geometrical characteristics of the cluster of pixels exited when a particle interacts with the sensor is recorded and used to identify the type of incoming particle, distinguishing between alpha particles and X-ray or gamma photons. The software was programmed in C using the OpenCV library. The system was tested with 137Cs and 241Am radiation sources.
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Lipovetzky, J., A. Cicuttin, M. L. Crespo, M. Sofo Haro, F. Alcalde Bessia, M. Pérez, and M. Gómez Berisso. "Multi-spectral X-ray transmission imaging using a BSI CMOS Image Sensor." Radiation Physics and Chemistry 167 (2020): 108244.
Abstract: In this work we study the performance to obtain X-ray images of a Back Side Illuminated CMOS Image Sensor, the Omnivision OV5647, empoying X-rays from tube with a palladium anode and voltages from 7.5 keV to 50 keV. The performance is compared with the Timepix detector operating in the Time Over Threshold mode. False color images are obtained using data from different energies and brightnesses, to fussion different information on the same picture. The different attenuations are analyzed and discussed in terms of the charge detection efficiency of the CMOS sensor, measured using Fluorescence X-rays and gamma rays from calibrated sources.
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Pérez, M., M. S. Haro, J. Lipovetzky, A. Cicuttin, M. L. Crespo, F. Alcade Bessia, M. Gómez Berisso, and J. J. Blostein. "Evaluation of a Commercial Off The Shelf CMOS Image Sensor for X-ray spectroscopy up to 24.9 keV." Radiation Physics and Chemistry 177 (2020): 109062.
Abstract: We studied the X-ray spectroscopy capability and the detection efficiency of a low cost Commercial Off The Shelf CMOS Image Sensor (CIS) in the energy range from 6.4 to 24.9 keV using the fluorescence spectra emitted by FeNi, Cu, Zr, Pb, and Ag. The obtained results are compared with that obtained using a Silicon Drift Detector (SDD). We conclude that CIS is able to resolve fluorescence lines up to 17.7 keV but with a reduced detection efficiency. At lower energies, the energy resolution of the CIS is comparable to that obtained with the SDD. By the comparison of both detectors we also estimate the detection efficiency of the proposed method and the effective thickness of the CIS for all the measured X-ray lines.
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Pérez, M., J. Lipovetzky, M. Sofo Haro, I. Sidelnik, J. J. Blostein, F. Alcalde Bessia, and M. Gómez Berisso. "Particle detection and classification using commercial off the shelf CMOS image sensors." Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment 827 (2016): 171.
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Pérez, M., E. D. Martínez, J. Lipovetzky, J. Marín, M. Sofo Haro, F. Alcalde Bessia, M. Gómez Berisso, and J. J. Blostein. "High spatial resolution neutron detection technique based on Commercial Off-The-Shelf CMOS image sensors covered with NaGdF_4 nanoparticles." Journal of Instrumentation 16 (2021): P08008.
Abstract: We present a position-sensitive neutron detection technique based on a Commercial Off-The-Shelf CMOS image sensor (CIS) covered with nanoparticles of sodium gadolinium fluoride (NaGdF4). The synthesis procedure and characterization of the NaGdF4 nanoparticles are detailed, as well as the deposition method of the conversion layers over the surface of the chips. We also present a manufacture method of test patterns made with neutron-absorbing materials. These patterns were designed to evaluate the performance of the proposed technique. Analyzing the obtained neutron images we conclude that the intrinsic spatial resolution of the developed method is better than (15±6) μm, this upper bound for the spatial resolution is comparable with that obtained with the best neutron position-sensitive detectors available nowadays.
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Pérez, M., M. Sofo Haro, I. Sidelnik, L. Tozzi, D. Rondón Brito, C. Mora, J. J. Blostein, M. Gómez Berisso, and J. Lipovetzky. "Commercial CMOS Pixel Array for Beta and Gamma Radiation Particle Counting." IEEE, Micro-Nanoelectronics, Technology and Applications (EAMTA) (2015): 11.
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Sereni, J. G., N. Caroca-Canales, M. Kumar, N. Oeschler, M. Gómez Berisso, and C. Geibel. "CeRuGe and CeRuSi: Heavy fermion systems with some unusual features." Journal of Physics: Conference Series 200, no. 1 (2010): 012181.
Abstract: We have investigated the physical properties of CeRuSi, its homologue CeRuGe and some doped La alloys. All of them present similar properties: large paramagnetic temperatures θp ##IMG## [http://ej.iop.org/icons/Entities/approx.gif] {approx} −100 K and the level off of χ( T ) below ##IMG## [http://ej.iop.org/icons/Entities/approx.gif] {approx} 10 K in coincidence with the maximum decrease of p ( T ), which starts to drop below 25 K. The respective γ ( CeRuSi ) ##IMG## [http://ej.iop.org/icons/Entities/approxeq.gif] {approxeq} 0.18 and γ ( CeRuGe ) ##IMG## [http://ej.iop.org/icons/Entities/approxeq.gif] {approxeq} 0.15 J/molK 2 coefficients reveal a heavy fermion character, with a Kondo temperature T K ##IMG## [http://ej.iop.org/icons/Entities/approxeq.gif] {approxeq} 50 K comparable to the crystal field splitting. In both compounds a broad maximum in C P ( T )/ T is observed around 5 K, whose origin is yet not clear. In contrast to the usual behavior observed in Kondo lattice systems, when Si is replaced by Ge T K ##IMG## [http://ej.iop.org/icons/Entities/propto.gif] {propto} θ p and 1/γ practically does not decreases despite the unit cell volume of CeRuGe is about 3% larger than that of CeRuSi. We discuss possible origins for these unusual features.
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