Scintillation efficiency of liquid argon in low energy neutron-argon scattering

Experiments searching for weak interacting massive particles with noble gases such as liquid argon require very low detection thresholds for nuclear recoils. A determination of the scintillation efficiency is crucial to quantify the response of the detector at low energy. We report the results obtained with a small liquid argon cell using a monoenergetic neutron beam produced by a deuterium-deuterium fusion source. The light yield relative to electrons was measured for six argon recoil energies between 11 and 120 keV at zero electric drift field.Comment: 21 pages, 19 figures, 4 table

Intraguild aggressiveness between an alien and a native predatory mite

The predatory mite Amblydromalus limonicus, non-native in Europe, can be used legally in several European countries as greenhouse biocontrol agent against thrips species, although this species is also able to feed on whiteflies and gall mites. The first record of the unintended occurrence of A. limonicus in apple orchards in Europe comes from Catalonia (Spain), where A. limonicus is well established in the native predatory mite community since 2011. The dominant species in this community is Amblyseius andersoni, which has a similar life-style as A. limonicus (large, aggressive predator with broad diet range) making intraguild (IG) interactions between the two predators likely. Thus, we tested the IG aggressiveness of native and alien female predators, when provided with IG prey (larvae). Alien females of A. limonicus proved to be highly aggressive IG predators against native larvae of A. andersoni, which were attacked earlier and more frequently than alien larvae by the native predator. Nearly all attacks by the alien predator resulted in the death of native IG prey, whereas about 10% of the alien intraguild prey escaped the attacks of the native predator. Additionally, native IG prey is smaller than alien prey, which should facilitate the overwhelming by the alien predator. We argue that the strong aggressive intraguild behavior of A. limonicus is contributing to its establishment success in the native predatory mite community.info:eu-repo/semantics/acceptedVersio

Preparation of 100−160-nm-sized branched palladium islands with enhanced electrocatalytic properties on HOPG

A method for the preparation of stable 100-160-nm-sized quasi-2D branched palladium islands on highly oriented pyrolitic graphite (HOPG) is described. This type of island is electrodeposited from an aqueous acidic palladium chloride solution containing an excess of sodium perchlorate at potentials just a few millivolts above the threshold potential of the hydrogen evolution reaction. Each branched palladium island consists of a central 3D core and large quasi-2D branches that form a dense radial pattern. In contrast to massive palladium, branched islands exhibit enhanced electrocatalytic properties for the hydrogen atom electroadsorption/electrodesorption reaction and the electrooxidation reaction of hydrazine. This enhancement is mainly related to the fractal characteristics of branched palladium islands on HOPG.Instituto de Investigaciones Fisicoquímicas Teóricas y AplicadasFacultad de Ciencias Exacta

Configuración de operación y puesta en marcha de un sistema de medición de transmitancia térmica

In this work, carried out within the framework of the UNLP research project 11-U177, we present the practical implementation of an original low-cost prototype of a thermal transmittance measurement system under steady state conditions. The theoretical model of measurement elaborated is presented, the components of the built measurement system are described and finally the steps to follow in the installation and assembly are indicated to carry out the thermal transmittance mediation of a wall of a house. The results obtained are compared with the value calculated from the procedure of Standard IRAM 11.601. The results of the tests carried out indicate that the system is capable of measuring thermal transmittances of walls for cases in which the temperature differences between the rooms on both sides of the wall are stable and greater than 8 °C.En este trabajo, realizado en el marco del proyecto de investigación 11-U177 de la UNLP, presentamos la implementación práctica de un prototipo original de bajo costo de un sistema de medición de transmitancia térmica en condiciones de estado estacionario. Se presenta el modelo teórico de medición elaborado, se describen los componentes del sistema de medición construido y finalmente se indican los pasos a seguir en la instalación y el montaje para realizar la mediación de transmitancia térmica de un muro de una vivienda. Los resultados obtenidos se comparan con el valor calculado a partir del procedimiento de la Norma IRAM 11.601. Los resultados de los ensayos realizados indican que el sistema es capaz de medir transmitancias térmicas de muros para los casos en que las diferencias de temperatura entre los ambientes a ambos lados del muro sean estables y mayores a 8 °C

Growth mode transition involving a potential-dependent isotropic to anisotropic surface atom diffusion change. Gold electrodeposition on HOPG followed by STM

The electrodeposition of gold on highly oriented pyrolytic graphite (HOPG) from acid aqueous solutions was studied by using electrochemical techniques complemented with ex-situ scanning tunneling microscopy (STM). The kinetics of gold electrodeposition is consistent with a nucleation and three-dimensional growth process under diffusion control from the solution side. As the applied potential moves in the negative direction, the gold crystal density increases, and the crystal shape changes from a Euclidean to a dendritic fractal morphology. This transition can be assigned to the anisotropic surface diffusion of gold adatoms induced by the applied electric potential. A model including a potential-dependent energy barrier at step edges accounts for the morphology transition for gold electrodeposition on HOPG.Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas (INIFTA)Facultad de Ciencias Exacta

Study of nuclear recoils in liquid argon with monoenergetic neutrons

For the development of liquid argon dark matter detectors we assembled a setup in the laboratory to scatter neutrons on a small liquid argon target. The neutrons are produced mono-energetically (E_kin=2.45 MeV) by nuclear fusion in a deuterium plasma and are collimated onto a 3" liquid argon cell operating in single-phase mode (zero electric field). Organic liquid scintillators are used to tag scattered neutrons and to provide a time-of-flight measurement. The setup is designed to study light pulse shapes and scintillation yields from nuclear and electronic recoils as well as from {\alpha}-particles at working points relevant to dark matter searches. Liquid argon offers the possibility to scrutinise scintillation yields in noble liquids with respect to the populations of the two fundamental excimer states. Here we present experimental methods and first results from recent data towards such studies.Comment: 9 pages, 8 figures, proceedings of TAUP 2011, to be published in Journal of Physics: Conference Series (JCPS

Warm Compressor system Overview and status of the PIP-II cryogenic system

The Proton Improvement Plan-II (PIP-II) is a major upgrade to the Fermilab accelerator complex, featuring a new 800-MeV Superconducting Radio-Frequency (SRF) linear accelerator (Linac) powering the accelerator complex to provide the world's most intense high-energy neutrino beam. The PIP-II Linac consists of 23 SRF cryomodules operating at 2 K, 5 K, and 40 K temperature levels supplied by a single helium cryoplant providing 2.5 kW of cooling capacity at 2.0 K. The PIP-II cryogenic system consists of two major systems: a helium cryogenic plant and a cryogenic distribution system. The cryogenic plant includes a refrigerator cold box, a warm compressor system, and helium storage, recovery, and purification systems. The cryogenic distribution system includes a distribution box, intermediate transfer line, and a tunnel transfer line consisting of modular bayonet cans which supply and return cryogens to the cryomodules. A turnaround can is located at the end of the Linac to turnaround cryogenic flows. This paper describes the layout, design, and current status of the PIP-II cryogenic system.Comment: 2023 Cryogenic Engineering Conference and International Cryogenic Materials Conference (CEC/ICMC

Plomo en aguas de consumo público de la provincia de Valencia

Questions made in a poll ellaborated in Department of Chemical Physics about the practices of Instrumental Techniques subject have been analyzed by mean of statistical procedures. Cluster analysis, variables dependence inference and n way classification have been the methods principally used. The results found case the elimination of unnecessary questions allowing its optimization. Besides, it helps the correct interpretation of the poll results.Mediante procedimientos estadísticos se ha analizado la hoja de preguntas empleada en una encuesta sobre las prácticas de la .asignatura de Técnicas Instrumentales. Los métodos utilizados han sido fundamentalmente el de análisis cluster, el de inferencia sobre la dependencia de las variables y el de clasificación con arreglo a n criterios. Los resultados encontrados facilitan la eliminación de preguntas innecesarias permitiendo así su optimización, a la vez que ayudan a interpretar más correctamente los resultados de la encuesta

Reconstrucción paleoclimática y paleoambiental de la Península Ibérica durante el Cuaternario, aplicación de modelos geoprospectivos para la evaluación de escenarios futuros

Esta comunicación trata de resumir el trabajo realizado por el ITGE, BRGM, CCMA, IPE, ETSIMM y ENRESA en el proyecto titulado "Paleoclimatological Revision of Climate Evolution and Environment in Western Mediterranean Region. Evaluation of future evolution scenarios in the Iberian Peninsula", en el marco del Programa de la Comisión de las Comunidades Europeas sobre Gestión y Almacenamiento de Residuos Radioactivos (contrato CEC FI2WCT91- 0075)

Estudio de las aguas de bebida minerales de las provincia de Valencia

Mediante la investigación de determinados parámetros, en las aguas de bebida minerales de la provincia de Valencia, buscamos la posible relación entre la composición de dichas aguas y las características geológicas de la zona. Del resultado de los análisis se deduce que las aguas menos mineralizadas se encuentran en los terrenos más antiguos del Buntsandstein de la zona Norte de la provincia, mientras que las más mineralizdadas las encontramos en terreno Keuper. La mayoría de las aguas minerales y de mesa se encuentran en terrenos triásicos o cretácicos. En las aguas de mesa que se explotan comercialmente predominan las bicarbonato-c4lcicas y bacteriológicamente suelen ser correctas si lo es la explotación. Del Mióceno y Cuaternario afloran aguas con sulfatos aumentados.With the investigation of determinates parameters in the mineral waters of the province of Valencia, we are looking for the possible relation between the composition of those water s and the geological characteristics of the zone. From the result of the analysis we deduce that the water s with minus mineralization are found al the oldest Buntsandstein terrenes of the north zone of the province, while the waters with more mineralization are found at Keu per terrene. The most mineral water s and potable waters are found at Triassic terrene or Cretaceous terrenes. About the waters to drink that are work com mercially predominate the bicarbonated-caIciumed and bacteriologicaly they used to be correct in the work is correct. From the Miocene and Quaternary emanate water s with increased sulphate