Cryogenic scintillation properties of n-type GaAs for the direct detection of MeV/c2 dark matter

This paper is the first report of n-type GaAs as a cryogenic scintillation radiation detector for the detection of electron recoils from interacting dark matter (DM) particles in the poorly explored MeV/c2 mass range. Seven GaAs samples from two commercial suppliers and with different silicon and boron concentrations were studied for their low temperature optical and scintillation properties. All samples are n-type even at low temperatures and exhibit emission between silicon donors and boron acceptors that peaks at 1.33 eV (930 nm). The lowest excitation band peaks at 1.44 eV (860 nm), and the overlap between the emission and excitation bands is small. The X-ray excited luminosities range from 7 to 43 photons/keV. Thermally stimulated luminescence measurements show that n-type GaAs does not accumulate metastable radiative states that could cause afterglow. Further development and use with cryogenic photodetectors promises a remarkable combination of large target size, ultra-low backgrounds, and a sensitivity to electron recoils of a few eV that would be produced by DM particles as light as a few MeV/c2

BaBrI:Eu2 + , a new bright scintillator

The scintillation properties of BaBrI:Eu2+ are reported. Crystals were produced by the vertical Bridgman technique in a sealed quartz ampoule. Excellent scintillation properties were measured. A light yield of 81,0007 +- 3000 photons per MeV (ph/MeV) of absorbed gamma-ray energy was measured. An energy resolution (FWHM over peak position) of 4.870.5percent was observed for the 662keV full absorption peak. Pulsed X-ray luminescence measurements show two exponential decay components of 297 and 482 ns with a contribution to the total light output of 23percent and 77percent, respectively. Under X-ray and UV excitation, the emission corresponds to a broadband center at 413 nm. These initial values make BaBrI:Eu2+ one of the brightest and the fastest known Eu2+ doped scintillators

Measurements of NaI:Tl Electron Response using SLYNCI: Comparison of Different Samples

This paper measures the sample to sample variation in the light yield non-proportionality of NaI:Tl, and so explores whether this is an invariant characteristic of the material or whether it is dependent on the chemical and physical properties of tested sample. In this work we report on the electron response of nine crystals of NaI(Tl), differing in shape, volume, age, manufacturer and quality. The non-proportionality has been measured at the SLYNCI facility in the energy range between 3.5 to 460 keV. The Scintillation Light Yield Non-proportionality Characterization Instrument (SLYNCI) is a next generation Compton Coincidence device, explicitly designed to study the 'non-proportionality' of the electron response in scintillators and the contribution of this effect to the intrinsic energy resolution. We also discuss the gamma response, x-ray excited emission spectra and decay times for the nine crystals, in order to provide a complete characterization of their physical properties and determine whether the mechanism of scintillation varies between samples

Two-dimensional perovskite functionalized fiber-type heterostructured scintillators

A fiber-type heterostructured scintillator based on bismuth germanate (Bi4Ge3O12) functionalized with the 2D-perovskite butylammonium lead bromide ((BA)2PbBr4) has been fabricated, and its scintillation performance analyzed toward its use for fast timing applications such as time-of-flight Positron Emission Tomography. The pixel shows energy sharing between the matrix and filler component, confirming that the two components are in synergy

Escuela de ayudantes alumnos: arte y parte del ayudante alumno como tutor de pares

La preocupación por cómo y para qué enseñar y aprender se muestra como una constante a lo largo del tiempo; ello invita a plantear alternativas innovadoras. Las experiencias en Escuelas de Ayudantes resultan alentadoras en capacitación docente; inserción en equipos docentes; mejoramiento en la formación de grado; integración transversal y vertical; reflexión crítica; apropiación de conocimientos; etc. Dentro del contexto de las “prácticas de docencia compartida”, precisamente le cabe a los alumnos compartir los procesos de aprendizaje entre ellos y los docentes. Objetivo: implementar un sistema de Tutorías de Pares en Histología en las dimensiones pedagógica y disciplinar. Participan del trabajo: docentes, no docente, asesora pedagógica y alumnos. Se preveen actividades áulicas y de Formación y Capacitación Pedagógica y Científica. Se aspira a estimular el pensamiento reflexivo entre el contenido teórico y la práctica profesional; generar un espacio de discusión y formulación de propuestas orientadas al mejoramiento del aprendizaje, propiciar el desarrollo de habilidades; capacitar al aspirante en actividades de docencia; ofrecer un ámbito para el desarrollo de actividades de investigación propiamente dichas y como saber científico aplicado a la docencia de grado; fomentar la habilidad para desempeñar tareas en equipo; favorecer la formación de recursos humanos desde el grado; abordar la problemática de deserción estudiantil. PIIMEG SECyTUNRC( 2011-2012).Eje temático 2: Los cambios e innovaciones en los procesos de formación a - Alternativas didácticas y experiencias de renovación de la enseñanzaFacultad de Ciencias Agrarias y Forestale