First results from a multiplexed and massive instrument with sub-electron noise Skipper-CCDs

We present a new instrument composed of a large number of sub-electron noise Skipper-CCDs operated with a two stage analog multiplexed readout scheme suitable for scaling to thousands of channels. New, thick, $1.35$ Mpix sensors, from a new foundry, are glued into a Multi-Chip Module (MCM) printed circuit board on a ceramic substrate which has 16 sensors each. The instrument, that can hold up-to 16 MCMs, a total of 256 Skipper-CCD sensors (called a Super-Module with $\approx 130$ grams of active mass and $346$ Mpix), is part of the R$\&$D effort of the OSCURA experiment which will have $\approx 94$ super-modules. Experimental results with $10$ MCMs and $160$ Skipper-CCDs sensors are presented in this paper. This is already the largest ever build instrument with single electron sensitivity CCDs using nondestructive readout, both, in terms of active mass and number of channels.Comment: Corrected minor typo

Skipper Charge-Coupled Device for Low-Energy-Threshold Particle Experiments above Ground

We present experimental results using a single-electron resolution skipper CCD running above ground level to demonstrate the potential of this technology for its use in reactor neutrino observations and other low-energy particle-interaction experiments. Operating conditions and event-selection criteria are provided to decouple most of the background rate at low energies. The majority of this background comes from interactions in the inactive silicon surrounding the active detector volume that ends up in the readout register of the sensor. Our final results are compared with other low-threshold technologies showing a good control of the background for low ionization energies down to five electron-hole pairs. This demonstrates that the skipper CCD proves to be among the best options to measure low-energy and weakly interacting particles at ground level

Palladium nanoparticles and nanowires deposited electrochemically: AFM and electrochemical characterization

Abstract Palladium nanoparticles and nanowires electrochemically deposited onto a carbon surface were studied using cyclic voltammetry, impedance spectroscopy and atomic force microscopy. The ex situ and in situ atomic force microscopy (AFM) topographic images showed that nanoparticles and nanowires of palladium were preferentially electrodeposited to surface defects on the highly oriented pyrolytic graphite surface and enabled the determination of the Pd nanostructure dimensions on the order of 50–150 nm. The palladium nanoparticles and nanowires electrochemically deposited onto a glassy carbon surface behave differently with respect to the pH of the electrolyte buffer solution. In acid or mild acid solutions under applied negative potential, hydrogen can be adsorbed/absorbed onto/into the palladium lattice. By controlling the applied negative potential, different quantities of hydrogen can be incorporated, and this process was followed, analysing the oxidation peak of hydrogen. It is also shown that the growth of the Pd oxide layer begins at negative potentials with the formation of a pre-monolayer oxide film, at a potential well before the hydrogen evolution region. At positive potentials, Pd(0) nanoparticles undergo oxidation, and the formation of a mixed oxide layer was observed, which can act as nucleation points for Pd metal growth, increasing the metal electrode surface coverage. Depending on thickness and composition, this oxide layer can be reversibly reduced. AFM images confirmed that the PdO and PdO2 oxides formed on the surface may act as nucleation points for Pd metal growth, increasing the metal electrode surface coverage

La agricultura familiar en el área hortícola de La Plata, Berazategui y Florencio Varela: Diversas formas de dependencia y el camino de construcción de su autonomía

Los horticultores familiares del Área Hortícola de La Plata, Berazategui y Florencio Varela, viven y trabajan en una situaciónde dependencia multicausal. La publicación que aquí se presenta analiza cómo esta condición se traduce en la situación de acceso y tenencia de la tierra, las formas de producción, sus estrategias de comercialización, la utilización de energías y la posibilidad de acceso al agua segura. Asimismo, plantea las alternativas posibles al sistema de producción intensivo, con amplia utilización de invernáculos. Presenta diferentes alternativas que sedesarrollan tanto desde el INTA, junto a otras instituciones, como desde organizaciones de productores, que coadyuvan a ladisminución de esa dependencia en pos de fortalecer la autonomía. El diagnóstico, como así también las alternativas productivas que aquí se presentan, fueron construidas a partir de fuentes bibliográficas, entrevistas semi-estructuradas en profundidad a informantes calificados y agricultores familiares de laregión, así como de resultados de investigaciones finalizadas (yalgunas en curso) de las diferentes líneas de investigación delIPAF Región Pampeana.Fil: Fingermann, Luciana. Instituto Nacional de Tecnología Agropecuaria; ArgentinaFil: Muscio, Luciana. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Instituto Nacional de Tecnología Agropecuaria; ArgentinaFil: Hall, Marcos Fernando. Instituto Nacional de Tecnología Agropecuaria; ArgentinaFil: Perez, R.. Instituto Nacional de Tecnología Agropecuaria; ArgentinaFil: Pérez, Maximiliano. Instituto Nacional de Tecnología Agropecuaria; ArgentinaFil: Dumrauf, Sergio. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Instituto Nacional de Tecnología Agropecuaria; ArgentinaFil: Giordano, Gabriel Alejandro. Instituto Nacional de Tecnología Agropecuaria; ArgentinaFil: Prividera, Guido. Instituto Nacional de Tecnología Agropecuaria; ArgentinaFil: González, Edgardo Gabriel. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Instituto Nacional de Tecnología Agropecuaria; ArgentinaFil: Justianovich, Sergio Hernan. Instituto Nacional de Tecnología Agropecuaria; ArgentinaFil: Muzi, M. E.. Instituto Nacional de Tecnología Agropecuaria; ArgentinaFil: Córdoba, Joaquín Alejandro. Instituto Nacional de Tecnología Agropecuaria; ArgentinaFil: Ocampo, F.. Instituto Nacional de Tecnología Agropecuaria; ArgentinaFil: Lavarello Herbin, Agustina. Instituto Nacional de Tecnología Agropecuaria; ArgentinaFil: Castro, A.. Instituto Nacional de Tecnología Agropecuaria; ArgentinaFil: Castro, A. S.. Instituto Nacional de Tecnología Agropecuaria; ArgentinaFil: Battista, Edurne. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Instituto Nacional de Tecnología Agropecuaria; ArgentinaFil: Chierchie, Laura. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Instituto Nacional de Tecnología Agropecuaria; ArgentinaFil: Novelli, M.. Instituto Nacional de Tecnología Agropecuaria; ArgentinaFil: Hang, Sofía. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Instituto Nacional de Tecnología Agropecuaria; Argentin

SENSEI: Characterization of Single-Electron Events Using a Skipper Charge-Coupled Device

We use a science-grade skipper charge-coupled device (skipper CCD) operating in a low-radiation background environment to develop a semiempirical model that characterizes the origin of single-electron events in CCDs. We identify, separate, and quantify three independent contributions to the single-electron events, which were previously bundled together and classified as "dark counts": dark current, amplifier light, and spurious charge. We measure a dark current, which depends on exposure, of (5.89±0.77)×10-4e-/pix/day, and an unprecedentedly low spurious charge contribution of (1.52±0.07)×10-4e-/pix, which is exposure independent. In addition, we provide a technique to study events produced by light emitted from the amplifier, which allows the detector's operation to be optimized to minimize this effect to a level below the dark-current contribution. Our accurate characterization of the single-electron events allows one to greatly extend the sensitivity of experiments searching for dark matter or coherent neutrino scattering. Moreover, an accurate understanding of the origin of single-electron events is critical to further progress in ongoing research and development efforts of skipper and conventional CCDs