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Fano and readout noise along with the partial charge collection (PCC) effect, are responsible for degrading the energy spectra in Charge Coupled Devices (CCD) measurements, especially at low energies. In this work, the X-ray produced by the fluorescence of fluorine (@677 eV) and aluminum (@1486 eV) were recorded using a Skipper-CCD, which enabled the reading noise to be reduced to 0.2e-. Based on an analytical description of the shape of photopeaks derived from the convolution of the PCC effect and Fano noise, we were able to accurately describe the energy spectra. This description accounts for lower energies tails, disentangling, and quantifying the contributions of Fano noise and PCC effect. Thus, the Fano factor and electron-hole pair creation energy were determined below 1 keV and, the PCC-region of the sensor was estimated. Additionally, the skewness of photopeaks expected at low energies was also experimentally observed for the first time., 7 pages, 5 figures

Oscura is a planned light-dark matter search experiment using Skipper-CCDs with a total active mass of 10 kg. As part of the detector development, the collaboration plans to build the Oscura Integration Test (OIT), an engineering test experiment with 10% of the Oscura's total mass. Here we discuss the early science opportunities with the OIT to search for millicharged particles (mCPs) using the NuMI beam at Fermilab. mCPs would be produced at low energies through photon-mediated processes from decays of scalar, pseudoscalar, and vector mesons, or direct Drell-Yan productions. Estimates show that the OIT would be a world-leading probe for low-mass mCPs., Comment: 21 pages, 13 figures

We present the first direct-detection search for eV-to-GeV dark matter using a new ~2-gram high-resistivity Skipper-CCD from a dedicated fabrication batch that was optimized for dark-matter searches. Using 24 days of data acquired in the MINOS cavern at the Fermi National Accelerator Laboratory, we measure the lowest rates in silicon detectors of events containing one, two, three, or four electrons, and achieve world-leading sensitivity for a large range of sub-GeV dark matter masses. Data taken with different thicknesses of the detector shield suggest a correlation between the rate of high-energy tracks and the rate of single-electron events previously classified as "dark current." We detail key characteristics of the new Skipper-CCDs, which augur well for the planned construction of the ~100-gram SENSEI experiment at SNOLAB., 5 pages, 4 figures, 1 table + Supplemental Materials (5 pages, 8 figures) + References. v3: matches version published in PRL

Desde su invención en 1969, los dispositivos de acoplamiento de carga o Charge Coupled Devices (CCDs) se han usado intensamente en la detección de radiación dentro del espectro visible e infrarrojo cercano, tanto en electrónica de consumo como para observación astronómicas. En las imágenes adquiridas con estos sensores, es posible observar algunas estructuras de algunos píxeles, producidas por la interacción de partículas. El desarrollo de CCD científicos fully-depleted ha permitido obtener dispositivos de hasta 675 µm de espesor y diez veces más masivos que los CCDs convencionales. Combinado a un bajo ruido de lectura, del orden de 2 e rms/pix, eso ha motivado su aplicación en experimentos de detección de partículas que depositan muy pequeña cantidad de energía en la materia, como materia oscura o neutrinos. Esta tesis se realizó en el marco de las colaboraciones de dos experimentos novedosos que hacen uso de esta tecnología: DAMIC (Dark Matter in CCDs) y CONNIE (Coherent Neutrino-Nucleous Interaction Experiment). Los aportes se enfocan principalmente en maximizar la relación señal-ruido de estos experimentos. Como parte del trabajo de tesis se montó desde cero una facilidad experimental en el Centro Atómico Bariloche para probar CCDs. Se realizó una caracterización exhaustiva de los mismos con diferentes tipos de radiación. Se los usó en detección de neutrones con la finalidad de desarrollar un técnica novedosa de neutrografía. Se trabajó en la instalación de CONNIE-100 g en el reactor nuclear Angra-1, participando en el montaje del blindaje, verificando sus detectores y electrónica de lectura en el laboratorio. Se estudió en detalle la imagen característica esperada por interacciones de materia oscura o neutrinos, denominada eventos puntuales. Debido a la falta de resolución temporal de los CCD, no es posible aplicar técnicas activas de rechazo de eventos de fondo. Por tal motivo, se desarrolló una técnica pasiva que consiste en procesar la imagen bidimensional de los eventos detectados para estimar su profundidad de interacción, y así poder aplicar cortes sobre esa variable. Para poder aumentar el número de eventos de señal detectados, se abordó el problema de la reducción del ruido electrónico de lectura. Se logró identificar las distintas fuentes de ruido, en particular la presencia de carga espuria generada durante la lectura de CCD fully-depleted. Se modificó y optimizó la electrónica de lectura logrando alcanzar un mínimo de 1.7 e rms/pix, lo cual implica un aumento del 20 % de la cia de CONNIE. Con el objetivo de reducir aún más el ruido de lectura, se trabajó en colaboración con los laboratorios Fermilab y LBNL (Lawrence Berkeley National Lab) en el desarrollo de un CCD fully-depleted del tipo skipper. La tecnología de skipper CCD fue propuesta por primera vez en 1979, y en esta tesis se logró la primer demostración fehaciente de su funcionamiento. Con el dispositivo se alcanzó un ultra bajo ruido de lectura sin precedentes de 0.068 e rms/pix, siendo la primera vez que se alcanza un nivel de ruido tan bajo que hace posible detectar electrones individuales en los píxeles de un detector estable de silicio de 8 cm2 (3.5 Mpix de 15x15 µm2). Al final de la tesis se presenta una aplicación inmediata del dispositivo, el experimento SENSEI (Sub-Electron Noise Skipper CCD Experimental Instrument), dedicado a la detección directa de materia oscura por electron-recoil. El mismo se instaló en un sitio subterráneo a ⇡ 100 metros de profundidad. El sensor tendrá probablemente otras aplicaciones, en particular donde se requiere la detección de fotones individuales como en la búsqueda de exoplanetas, espectroscopia celeste y de laboratorio de ultra alta resolución. Since their invention in 1969, Charge Coupled Devices (CCDs) have been thoroughly used as photon detectors in the visible and near infrared range, both in consumer electronics and astronomy. In the images produced by these sensors it is sometimes possible to see structures of some pixels, produced by the interaction of particles. The development of fully-depleted CCDs has made it possible to obtain devices with thickness up to 675 µm, and at least ten times more massive than conventional CCDs. Together with their low read-out noise, of at least 2 e rms/pix, it has motivated their application in experiments detecting particles that deposit very low amount of energy in matter, like dark matter (DM) or neutrinos. This thesis took place within two novel experiments that use this technology: DAMIC (Dark Matter in CCDs) and CONNIE (Coherent Neutrino-Nucleous Interaction Experiment). The contributions are focused on improving the signal-to-noise ratio of these experiments. As part of the work, an experimental facility to test CCDs in the Bariloche Atomic Center was developed. An exhaustive characterization of the CCDs with differents types of radiation was performed. The CCDs were then applied in neutron detection with the aim to achieve a high resolution neutrography detector. Work was carried out on the installation of CONNIE-100 g in the Angra-1 nuclear reactor, participating in the assembly of the shield, characterizing its detectors and read-out electronics in the laboratory. A detailed analysis of the characteristic image espected by the interaction of DM or neutrinos in CCDs, called point-like events, was performed. Due to the lack of temporal resolution of CCDs, it is not possible to apply active background rejection techniques. For this reason, a passive technique was developed, which consists of processing the two-dimensional image of the detected events to estimate their depth, and then apply cuts on that variable. The reduction of the electronic read-out noise was studied in order to increase the number of detected signal events. Different sources of noise were identified, showing the presence of spurious charge generated during the reading of fully-depleted CCDs. The front-end of the read-out electronics was re-designed and optimized, achieving a minimun read-out noise of 1.7 e rms/pix that implies an improvement of the 20 % in the efficiency of CONNIE. In order to further reduce the read-out noise, in collaboration with Fermilab and LBNL (Lawrence Berkeley National Lab), a skipper-type fully-depleted CCD was developed. The skipper CCD technology was first proposed in 1979 but its operation could not be successfully demonstrated. With the developed device, an extremely low read-out noise of 0.068 e rms/pix was achieved, allowing single electron per pixel counting. This is the first time that discrete sub-electron readout noise has been achieved reproducibly over millions of pixels on a stable, large-area detector (⇡ 8 cm2). The thesis ends with the SENSEI (Sub-Electron Noise Skipper CCD Experimental Instrument) experiment, an immediate application of the skipper CCD. It is based on DM detection by electron-recoil, and installed in an underground site at ⇡ 100 m depth. In addition to ultra low threshold particle detection experiments, the device could likely be used when single-photon detection is required, like in exoplanets searches, or celestial and laboratory spectroscopy. Fil: Sofo Haro, Miguel Francisco. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte; Argentina. Comisión Nacional de Energía Atómica. Gerencia del Area Investigación y Aplicaciones No Nucleares. Gerencia de Física (Centro Atómico Bariloche). Grupo de Partículas y Campos; Argentina

Kilminster, Ben "The DAMIC-100 dark matter detection experiment with CCDs at SNOLAB " in Proceedings, 10th Patras Workshop on Axions, WIMPs and WISPs (AXION-WIMP 2014) / Tsesmelis, Emmanuel, Maroudas, Marios (eds.), Verlag Deutsches Elektronen-Synchrotron : 2014 ; AXION-WIMP 2014 : 10th Patras Workshop on Axions, WIMPs and WISPs, 2014-06-29 - 2014-07-04, Geneva 10th Patras Workshop on Axions, WIMPs and WISPs, AXION-WIMP 2014, Geneva, Switzerland, 29 Jun 2014 - 4 Jul 2014 ; DESY-PROC 25-28(2014). doi:10.3204/DESY-PROC-2014-03/kilminster_ben, The DAMIC (Dark Matter in CCDs) experiment uses the fully depleted silicon of CCDs (Charge Coupled Devices) as a target for galactic dark matter. The ionization energy threshold for detecting nuclear recoils of dark matter reaches down to 50 eV$_{ee}$, resulting in better sensitivity to dark matter with mass below 5 GeV than other direct dark matter detection experiments. Installation of the DAMIC-100 experiment at SNOLAB is ongoing and we present our expected sensitivity, which will extend the reach to low-mass dark matter cross sections within a year of operation., Published by Verlag Deutsches Elektronen-Synchrotron, Hamburg

The Oscura experiment will lead the search for low-mass dark matter particles using a very large array of novel silicon Charge Coupled Devices (CCDs) with a threshold of two electrons and with a total exposure of 30 kg-yr. The R&D effort, which began in FY20, is currently entering the design phase with the goal of being ready to start construction in late 2024. Oscura will have unprecedented sensitivity to sub-GeV dark matter particles that interact with electrons, probing dark matter-electron scattering for masses down to 500 keV and dark matter being absorbed by electrons for masses down to 1 eV. The Oscura R&D effort has made some significant progress on the main technical challenges of the experiment, of which the most significant are engaging new foundries for the fabrication of the CCD sensors, developing a cold readout solution, and understanding the experimental backgrounds.