Experimental Setup of the Fast Current Controller for the Buenos Aires Heavy Ion Microbeam

Recently we used the heavy ion microprobe of the Buenos Aires TANDAR Laboratory for Single Event Effects (SEE) and Total Dose (TD) experiments in electronics devices and components, requiring very low beam currents. The facility includes a fast beam switch that allows the control of the ion beam current and a mobile Si PIN (p-type, intrinsic, n-type) diode that directly measures the number of ions hitting the device. The fast beam deflector was used to reduce the current by producing a pulsed beam or generating a quasi-continuous (Poisson-like distributed) beam with currents ranging from tens to hundreds of ions/s. As an application for this current control method we present a single event effect (SEE) pulses map generated by a 32S8+ beam at 75 MeV on two 0.5 µm technology CMOS digital output buffers where the device was formed by cascading four CMOS inverters with increasing sizes from input to output to drive large loads. Using the same concept of pulse width modulated deflection, we developed a novel gradient scanning method. This system allows to produce in a single irradiation a distribution with a cumulative damage with a difference of two orders of magnitude at constant gradient. To demonstrate the method, we irradiated a lithium niobate monocrystal with 32S8+ beam at 75 MeV energy and later analyzed the produced damage by the micro-Raman technique and an optical profilomete.Fil: Vega, Nahuel Agustín. Comisión Nacional de Energía Atómica. Centro Atómico Constituyentes. Gerencia de Investigación y Aplicaciones; Argentina. Universidad Nacional de San Martín. Escuela de Ciencia y Tecnología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Müller, Nahuel Agustín. Comisión Nacional de Energía Atómica. Centro Atómico Constituyentes. Gerencia de Investigación y Aplicaciones; ArgentinaFil: De la Fourniére, Emmanuel. Comisión Nacional de Energía Atómica. Centro Atómico Constituyentes. Gerencia de Investigación y Aplicaciones; Argentina. Universidad Nacional de San Martín. Escuela de Ciencia y Tecnología; ArgentinaFil: Halac, Emilia Beatriz. Comisión Nacional de Energía Atómica. Centro Atómico Constituyentes. Gerencia de Investigación y Aplicaciones; Argentina. Universidad Nacional de San Martín. Escuela de Ciencia y Tecnología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Debray, Mario Ernesto. Comisión Nacional de Energía Atómica. Centro Atómico Constituyentes. Gerencia de Investigación y Aplicaciones; Argentina. Universidad Nacional de San Martín. Escuela de Ciencia y Tecnología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Determinación del mercurio en tejidos vegetales por microPIXE: Aplicación al estudio de la hiperacumulación por Spirodela intermedia (Lemnaceae)

Background and aims: Aqueous mercury (II), Hg2+, is still nowadays a hazardous pollutant with a large dispersion. Phytoremediation strategies are an environmental friendly and low-cost alternative. In order to improve these processes, Spirodela intermedia, an autochthonous floating macrophyte, was used to remove Hg2+ from mineral water under laboratory conditions, studying the in vivo distribution of mercury and other elements by nuclear microprobe scanning mapping. M&M: Exposures (1 and 10 mg.L-1 Hg2+ concentrations) were performed during at least 2 weeks. All the parameters from the bioremediation process as uptake rate, bioconcentration factors (BCFs) of mercury in roots and leaves and translocation factors (TFs), were achieved from microPIXE quantifications at Buenos Aires Tandar accelerator. Results: For 1 and 10 mg.L-1 concentrations, S. intermedia can be considered as a hyperaccumulator. The highest BCFs (> 1000 in roots and > 200 in leaves) were obtained for 1 mg.L-1 of Hg2+ at 96 h. In all cases TFs 1000 en raíces y > 200 en frondes) correspondieron a 1 mg.L-1 a las 96 hs. En todos los casos, se constató que TFs < 1, indicando que no ocurre translocación de Hg2+. Se obtuvieron mapas 2D de alta resolución espacial de la distribución elemental in vivo para las diferentes condiciones. Se observó que la distribución de mercurio en frondes es más heterogénea que en raíces. Fue importante la detección de Hg en clorénquima donde sus efectos son más tóxicos. Se analizó una correlación entre la distribución de mercurio y calcio y la relación con respuestas fisiológicas. Conclusiones: La fitorremediación de Hg2+ con S. intermedia es una alternativa conveniente. Por haberse realizado en agua real, el protocolo es escalableFil: De La Fournière, Emmanuel M.. Comisión Nacional de Energía Atómica. Centro Atómico Constituyentes. Gerencia de Investigación y Aplicaciones; Argentina. Universidad Nacional de San Martín. Escuela de Ciencia y Tecnología; ArgentinaFil: Vega, Nahuel Agustín. Comisión Nacional de Energía Atómica. Centro Atómico Constituyentes. Gerencia de Investigación y Aplicaciones; Argentina. Universidad Nacional de San Martín. Escuela de Ciencia y Tecnología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Müller, Nahuel Agustín. Comisión Nacional de Energía Atómica. Centro Atómico Constituyentes. Gerencia de Investigación y Aplicaciones; Argentina. Universidad Nacional de San Martín. Escuela de Ciencia y Tecnología; ArgentinaFil: Pizarro, Ramón Augusto. Comisión Nacional de Energía Atómica. Gerencia de Área de Aplicaciones de la Tecnología Nuclear. Departamento de Radiobiología; ArgentinaFil: Debray, Mario Ernesto. Comisión Nacional de Energía Atómica. Centro Atómico Constituyentes. Gerencia de Investigación y Aplicaciones; Argentina. Universidad Nacional de San Martín. Escuela de Ciencia y Tecnología; Argentin

Millimeter length micromachining using a heavy ion nuclear microprobe with standard magnetic scanning

In order to increase the scanning length of our microprobe, we have developed an irradiation procedure suitable for use in any nuclear microprobe, extending at least up to 400% the length of our heavy ion direct writing facility using standard magnetic exploration. Although this method is limited to patterns of a few millimeters in only one direction, it is useful for the manufacture of curved waveguides, optical devices such Mach-Zehnder modulators, directional couplers as well as channels for micro-fluidic applications. As an example, this technique was applied to the fabrication of 3mm 3D-Mach-Zehnder modulators in lithium niobate with short Y input/output branches and long shaped parallel-capacitor control electrodes. To extend and improve the quality of the machined structures we developed new scanning control software in LabViewTM platform. The new code supports an external dose normalization, electrostatic beam blanking and is capable of scanning figures at 16 bit resolution using a National InstrumentsTM PCI-6731 High-Speed I/O card. A deep and vertical micromachining process using swift 35Cl ions 70 MeV bombarding energy and direct write patterning was performed on LiNbO3, a material which exhibits a strong natural anisotropy to conventional etching. The micromachined structures show the feasibility of this method for manufacturing micro-fluidic channels as well.Fil: Nesprias, Francisco Jose Gabriel. Comisión Nacional de Energía Atómica. Centro Atómico Constituyentes. Gerencia de Investigación y Aplicaciones; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Debray, Mario Ernesto. Universidad Nacional de San Martín. Escuela de Ciencia y Tecnología; Argentina. Comisión Nacional de Energía Atómica. Centro Atómico Constituyentes. Gerencia de Investigación y Aplicaciones; ArgentinaFil: Davidson, Jorge. Comisión Nacional de Energía Atómica. Centro Atómico Constituyentes. Gerencia de Investigación y Aplicaciones; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Kreiner, Andres Juan. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de San Martín. Escuela de Ciencia y Tecnología; Argentina. Comisión Nacional de Energía Atómica. Centro Atómico Constituyentes. Gerencia de Investigación y Aplicaciones; ArgentinaFil: Vega, Nahuel Agustín. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Comisión Nacional de Energía Atómica. Centro Atómico Constituyentes. Gerencia de Investigación y Aplicaciones; ArgentinaFil: de la Fourniere, Emanuel María. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Comisión Nacional de Energía Atómica. Centro Atómico Constituyentes. Gerencia de Investigación y Aplicaciones; Argentin

Pulse Quenching and Charge-Sharing Effects on Heavy-Ion Microbeam Induced ASET in a Full-Custom CMOS OpAmp

In this work, charge sharing effects on Analog Single Event Transients are experimentally observed in a fully-custom designed, 180nm CMOS Operational Amplifier by means of a heavy-ion microbeam. Sensitive nodes of the differential stage showed bipolar output transients that cannot be explained by single node collection for the closed loop characteristics of the circuit under test. Layout of these transistors are consistent with charge sharing effects due to deposited charge diffusion. Implementation of linear modeling and simulations of multiple node collection between paired transistors of the input stage showed great coincidence with the obtained experimental waveforms, shaped as bipolar, quenched pulses. These effects are also observed due to dummy transistors placed in the layout. A simple parametrization at the simulation level is proposed to reproduce the observed experimental waveforms. Results indicate that charge-sharing effects should be taken into account during simulation-based sensitivity evaluation of analog circuits, as pulse quenching can alter the obtained results, and linear modeling is a simple approach to emulate simultaneous charge collection in multiple nodes by applying superposition principles, with aims of hardening a design.Fil: Fontana, Andrés. Universidad Tecnológica Nacional; ArgentinaFil: Pazos, Sebastián Matías. Comisión Nacional de Energía Atómica. Gerencia de Área Investigaciones y Aplicaciones No Nucleares. Gerencia Física (CAC). Departamento de Física de la Materia Condensada; Argentina. Universidad Tecnológica Nacional; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Aguirre, Fernando Leonel. Comisión Nacional de Energía Atómica. Gerencia de Área Investigaciones y Aplicaciones No Nucleares. Gerencia Física (CAC). Departamento de Física de la Materia Condensada; Argentina. Universidad Tecnológica Nacional; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Vega, Nahuel Agustín. Comisión Nacional de Energía Atómica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Muller, Nahuel. Comisión Nacional de Energía Atómica; ArgentinaFil: De la Fourniere, Emmanuel. Comisión Nacional de Energía Atómica; ArgentinaFil: Silveira, Fernando. Universidad de la Republica. Facultad de Ingeniería; UruguayFil: Debray, Mario Ernesto. Comisión Nacional de Energía Atómica; ArgentinaFil: Palumbo, Félix Roberto Mario. Comisión Nacional de Energía Atómica. Gerencia de Área Investigaciones y Aplicaciones No Nucleares. Gerencia Física (CAC). Departamento de Física de la Materia Condensada; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

COVID-19 symptoms at hospital admission vary with age and sex: results from the ISARIC prospective multinational observational study

Background: The ISARIC prospective multinational observational study is the largest cohort of hospitalized patients with COVID-19. We present relationships of age, sex, and nationality to presenting symptoms. Methods: International, prospective observational study of 60 109 hospitalized symptomatic patients with laboratory-confirmed COVID-19 recruited from 43 countries between 30 January and 3 August 2020. Logistic regression was performed to evaluate relationships of age and sex to published COVID-19 case definitions and the most commonly reported symptoms. Results: ‘Typical’ symptoms of fever (69%), cough (68%) and shortness of breath (66%) were the most commonly reported. 92% of patients experienced at least one of these. Prevalence of typical symptoms was greatest in 30- to 60-year-olds (respectively 80, 79, 69%; at least one 95%). They were reported less frequently in children (≤ 18 years: 69, 48, 23; 85%), older adults (≥ 70 years: 61, 62, 65; 90%), and women (66, 66, 64; 90%; vs. men 71, 70, 67; 93%, each P &lt; 0.001). The most common atypical presentations under 60 years of age were nausea and vomiting and abdominal pain, and over 60 years was confusion. Regression models showed significant differences in symptoms with sex, age and country. Interpretation: This international collaboration has allowed us to report reliable symptom data from the largest cohort of patients admitted to hospital with COVID-19. Adults over 60 and children admitted to hospital with COVID-19 are less likely to present with typical symptoms. Nausea and vomiting are common atypical presentations under 30 years. Confusion is a frequent atypical presentation of COVID-19 in adults over 60 years. Women are less likely to experience typical symptoms than men

Espectroscopía de los isótonos transicionales doblemente impares 218 Ac y 216 Fr

Fil: Debray, Mario Ernesto. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina

Preliminary results of the degradation of platinum based catalyst in PEM fuel cells using PIXE

This work reports the first results obtained on the dissolution and reprecipitation of platinum nanoparticles in the catalyst-membrane boundary of the MEA of a PEM fuel cell after 700 hours of operationunder open circuit conditions. The formation of a platinum line on the membrane side near the cathode will be monitored using the PIXE technique in the ion beam facility at Tandar. The MEA used in the experiment was acommercial one (E-TEK), having a Nafion membrane and nanoparticulated Pt catalyst (loading 40%) on both, anodic and cathodic sides. Details of the sample preparation, the operating fuel cell parameters and the cuttingprocedure of the MEA previous to the ion beam analysis are described. The spatial resolution of the technique is discussed, along with the importance of the results for modelling the catalyst degradation in PEM fuel cells.Fil: Gunther, Maria Virginia. Comisión Nacional de Energía Atómica; ArgentinaFil: Debray, Mario Ernesto. Comisión Nacional de Energía Atómica; ArgentinaFil: Corti, Horacio Roberto. Comisión Nacional de Energía Atómica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Preliminary results of the degradation of platinum based catalyst in PEM fuel cells using PIXE

This work reports the first results obtained on the dissolution and reprecipitation of platinum nanoparticles in the catalyst-membrane boundary of the MEA of a PEM fuel cell after 700 hours of operationunder open circuit conditions. The formation of a platinum line on the membrane side near the cathode will be monitored using the PIXE technique in the ion beam facility at Tandar. The MEA used in the experiment was acommercial one (E-TEK), having a Nafion membrane and nanoparticulated Pt catalyst (loading 40%) on both, anodic and cathodic sides. Details of the sample preparation, the operating fuel cell parameters and the cuttingprocedure of the MEA previous to the ion beam analysis are described. The spatial resolution of the technique is discussed, along with the importance of the results for modelling the catalyst degradation in PEM fuel cells.Fil: Gunther, Maria Virginia. Comisión Nacional de Energía Atómica; ArgentinaFil: Debray, Mario Ernesto. Comisión Nacional de Energía Atómica; ArgentinaFil: Corti, Horacio Roberto. Comisión Nacional de Energía Atómica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Evolution of the gate current in 32 nm MOSFETs under irradiation

Radiation induced currents on single 32 nm MOSFET transistors have been studied using consecutive runs of 16 O at 25 MeV. The main feature is the generation of current peaks ? in the gate and channel currents ? due to the collection of the electro?hole pairs generated by the incident radiation runs. It has been observed that the incident ions cause damage in the dielectric layer and in the substrate affecting the collection of carriers, and hence the radiation-induced current peaks. It has been find out a decrease of the current peak due to the increase of the series resistance by non-ionizing energy loss in the semiconductor substrate, and an increase of the leakage current due to defects in the gate oxide by ionizing energy loss. For low levels of damage in the gate oxide, the main feature is the shift of the VTH. Hot carriers heated by the incident radiation in the depletion region and injected in the gate oxide cause the change of the VTH due to electron or hole trapping for n- or p-channel respectively. The overall results illustrate that these effects must be taken into consideration for an accurate reliability projection.Fil: Palumbo, Félix Roberto Mario. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Tecnológica Nacional; Argentina. Comisión Nacional de Energía Atómica; ArgentinaFil: Debray, Mario Ernesto. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Comisión Nacional de Energía Atómica; ArgentinaFil: Vega, Nahuel Agustín. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Comisión Nacional de Energía Atómica; ArgentinaFil: Quinteros, Cynthia Paula. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Comisión Nacional de Energía Atómica; ArgentinaFil: Kalstein, Ariel. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Comisión Nacional de Energía Atómica; ArgentinaFil: Guarin, F.. Hopewell Junction; Estados Unido

MicroPIXE analysis of removal of aqueous U(VI) by S. intermedia and P. stratiotes in the presence of Th(IV)

In this work, Spirodela intermedia and Pistia stratiotes, autochthonous floating macrophytes, were used to remove aqueous UO22+ (1 and 10 mg.L−1) under laboratory conditions. The influence of Th4+(1 mg.L−1) was studied for the highest concentration of U(VI). All the parameters of the bioremediation process, bioconcentration factors (BCFs) in roots and leaves and translocation factors (TFs), were achieved by microPIXE quantification. This analysis was carried out using a 50-MeV 16O5+ beam with the aid of the heavy-ion microprobe at the TANDAR Laboratory in Buenos Aires. High resolution 2D maps of the in vivo elemental distribution in macrophytes for different conditions were obtained. Both plants have the ability to accumulate a large amount of U(VI) yielding BCFs > 500. Only S. intermedia can additionally uptake Th(IV) reaching a high BCF (>300 at 96 h) but the plant does not survive; Th was detected within the chlorenchyma ([Th] ≅ 30 µg.g−1).Fil: de la Fourniere, Emanuel María. Comisión Nacional de Energía Atómica. Centro Atómico Constituyentes. Gerencia de Investigación y Aplicaciones; Argentina. Universidad Nacional de San Martín. Escuela de Ciencia y Tecnología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Vega, Nahuel Agustín. Comisión Nacional de Energía Atómica. Centro Atómico Constituyentes. Gerencia de Investigación y Aplicaciones; Argentina. Universidad Nacional de San Martín. Escuela de Ciencia y Tecnología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Müller, Nahuel Agustín. Universidad Nacional de San Martín. Escuela de Ciencia y Tecnología; Argentina. Comisión Nacional de Energía Atómica. Centro Atómico Constituyentes. Gerencia de Investigación y Aplicaciones; ArgentinaFil: Debray, Mario Ernesto. Comisión Nacional de Energía Atómica. Centro Atómico Constituyentes. Gerencia de Investigación y Aplicaciones; Argentina. Universidad Nacional de San Martín. Escuela de Ciencia y Tecnología; Argentin