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. Gomez Berisso, N. Piunno, H. Mateos, F. J. Pomiro, I. Sidelnik, J. J. Blostein, M. Sofo Haro, and J. Lipovetzky. "X-ray micrographic imaging system based on COTS CMOS sensors." In 2017 Argentine Conference of Micro-Nanoelectronics, Technology and Applications (CAMTA), 1–4. 2017 Argentine Conference of Micro-Nanoelectronics, Technology and Applications (CAMTA)., 2017.
Abstract: This paper presents the use of Commercial Off The Shelf CMOS image sensors for the acquisition of X-ray images with high spatial resolution. The X-ray images, with application in biology, electronic components inspection or paleontology research, are obtained with 8 keV photons from a Cu tube. The quantum efficiency of the detector is estimated using attenuation lengths of photons in the sensor, and compared to traditional scintillator conversion layers.
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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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Antonio, D., M. I. Dolz, and H. Pastoriza. "Micromechanical magnetometer using an all-silicon nonlinear torsional resonator." Applied Physics Letters 95, no. 13 (2009): 133505–3.
Abstract: In this work, a micromagnetometer employing a nonlinear torsional resonator with a high quality factor Q is presented experimentally. Oscillatory rotation of a conducting plate in the sensed magnetic field H induces eddy currents that dissipate energy. Due to the nonlinear response of the oscillator, the resulting mechanical damping originates frequency shifts in the resonance curve that depend on H. Nonlinearity results from the electrostatic detection, which introduces high order electrical spring constants. The device is fabricated with a standard silicon process and does not incorporate ferromagnetic materials. An analytical nonlinear model that correctly describes the device is also introduced.
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Frank, V. L. P., and M. E. de la Cruz. "Low temperature specific heat of Dow Corning Silicon Oil No 704 between 2 and 18 K." Cryogenics 24, no. 6 (1984): 311–312.
Abstract: The specific heat of Dow Corning Silicon Oil No 704 was measured between 2 and 18 K. Below 5 K it was found to follow a T3 law. Throughout the range it could be fitted with a 5th order polynomial in T.
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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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Pedrazzini, P., D. Jaccard, G. Lapertot, J. Flouquet, Y. Inada, H. Kohara, and Y. Onuki. "Probing the extended non-Fermi liquid regimes of MnSi and Fe." Physica B – Condensed Matter 378-380 (2006): 165–166.
Abstract: Recent studies show that the non-Fermi liquid (NFL) behavior of MnSi and Fe spans over an unexpectedly broad pressure range, between the critical pressure p and around 2p. In order to determine the extension of their NFL regions, we analyze the evolution of the resistivity ρ(T)˜A(p)T at higher pressures. We find that in MnSi the n=32 exponent holds below 4.8GPa≈3p, but it increases above that pressure. At 7.2 GPa we observe the low-temperature Fermi liquid exponent n=2 whereas for T>1.5K, n=53. Our measurements in Fe show that the NFL behavior ρ˜T extends at least up to 30.5 GPa, above the entire superconducting (SC) region. In the studied pressure range, the onset of the SC transition reduces by a factor 10 down to Tconset(30.5GPa)=0.23K, while the A—coefficient diminishes monotonically by around 50%.
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Sarkar, R., M. Baenitz, J. G. Sereni, and C. Geibel. "29Si NMR study of the heavy fermion system CeRuSi." Journal of Physics: Conference Series 200 (2010): 012173.
Abstract: A recent investigation of the low temperature properties of the paramagnetic heavy fermion system CeRuSi revealed an anomalous decrease of the coefficient C/T below 6 K, indicating a second low energy scale well below the Kondo temperature of about 50 K. We started an investigation of this unusual behavior using the local probe 29Si-NMR. Here a preliminary 29Si field sweep NMR study in the temperature 4.2-200 K is reported. 29Si-NMR powder spectra obtained at 72.9 MHz could be simulated and shift components 29Kab(T) and 29K c(T) were determined. The shift along the basal plane 29Kab(T) shows the expected behavior with a Curie-Weiss dependence at high T merging in a constant value below 15 K. In contrast the shift along the tetragonal axis reveals an anomalous T dependence below 15 K where 29Kc(T) drops by a factor of 2, confirming the presence of a further low T energy scale. We suspect this drop to be related to the anomalous decrease of C/T below 6 K and discuss possible mechanism. © 2010 IOP Publishing Ltd.
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