10 research outputs found
Origin and characterization of single-electron events in Skipper-CCDs for light dark matter searches
This manuscript summarizes the work carried out within the SENSEI
(Sub-Electron-Noise Skipper-CCD Experimental Instrument) collaboration, an
effort focused on the search for light dark matter using Skipper-CCDs. Firstly,
it presents the data acquisition and processing protocol developed to establish
a selection criteria for events compatible with the dark matter signal. This
protocol also enabled the structure and tools used for the study and
characterization of phenomena that impact the quality of measurements made in
the search for dark matter (measurement of the Fano factor, determination of
the Compton background, and characterization of the high-energy surface
background), which were carried out during this work. Secondly, it discusses
the comprehensive study conducted on the origin of single-electron events in
Skipper-CCDs, which allowed for the selection of detector operating parameters
and improved the detection sensitivity in the search for dark matter. It is
highlighted the characterization of the spatial correlation between
single-electron events and high-energy events, among other developed event
selection criteria, and the optimization of the output device to reduce sources
of luminescence during its operation. As a result of this study, the lowest
levels of dark current and spurious charge ever measured in a CCD are reported.
Finally, the latest published results from SENSEI are presented. The obtained
limits for the scattering of a light mediator are the best reported to date
across the entire investigated mass range, while for the heavy mediator, they
are the best for masses below 10 MeV. In terms of dark matter absorption, the
most restringent limits below 10 eV are reported. These results, achieved with
only a very small fraction of the total projected exposure for SENSEI, position
Skipper-CCDs as leaders in the search for light dark matter worldwide.Comment: This document is an English translation of a Ph.D. Thesis. The
original version of this thesis was written in Spanish and is available for
reference online in the digital archive of Ph.D. theses at the UBA,
Argentina. This translation is unofficial and has been attempted by the
author solely for the purpose of facilitating its diffusion and wider
accessibility to the scientific communit
Unraveling Fano noise and partial charge collection effect in X-ray spectra below 1 keV
Fano noise, readout noise, and the partial charge collection (PCC) effect
collectively contribute to the degradation of 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
0.2 e-. Based on an analytical description of photopeak shapes resulting from
the convolution of the PCC effect and Fano noise, we achieved a precise
characterization of the energy spectra. This description enabled us to
disentangle and quantify the contributions from both Fano noise and the PCC
effect. As a result, we determined the Fano factor and the electron-hole pair
creation energy. Additionally, we estimated the PCC-region of the sensor and,
for the first time, experimentally observed the expected skewness of photopeaks
at low energies.Comment: 8 pages, 5 figure
SENSEI: Characterization of Single-Electron Events Using a Skipper-CCD
We use a science-grade Skipper Charge Coupled Device (Skipper-CCD) operating
in a low-radiation background environment to develop a semi-empirical 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)x10^-4 e-/pix/day, and an
unprecedentedly low spurious charge contribution of (1.52+-0.07)x10^-4 e-/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 R&D efforts of Skipper and conventional
CCDs.Comment: 9 pages, 6 figures, 4 table
Absolute measurement of the Fano factor using a Skipper-CCD
Skipper-CCD can achieve deep sub-electron readout noise making possible the absolute determination of the exact number of ionized electrons in a large range, from 0 to above 1900 electrons. In this work we present a novel technique that exploits this unique capability to allow self-calibration and the ultimate determination of silicon properties. We performed an absolute measurement of the variance and the mean number of the charge distribution produced by 55Fe X-rays, getting a Fano factor absolute measurement in Si at 123K and 5.9 keV. A value of 0.1190(25) was found and the electron–hole pair creation energy was determined to be 3.752(2) eV. This technology opens the opportunity for direct measurements of the Fano factor at low energies.Fil: Rodrigues Ferreira Maltez, Dario Pablo. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Física de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Física de Buenos Aires; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Física; Argentina. Fermi National Accelerator Laboratory; Estados UnidosFil: Andersson, Kevin. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Física; Argentina. Fermi National Accelerator Laboratory; Estados UnidosFil: Cababie, Mariano Ruben. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Física de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Física de Buenos Aires; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Física; Argentina. Fermi National Accelerator Laboratory; Estados UnidosFil: Donadón Servelle, André. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Física; Argentina. Fermi National Accelerator Laboratory; Estados UnidosFil: Botti, Ana Martina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Física de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Física de Buenos Aires; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Física; Argentina. Fermi National Accelerator Laboratory; Estados UnidosFil: Cancelo, Gustavo. Fermi National Accelerator Laboratory; Estados UnidosFil: Estrada, Juan. Fermi National Accelerator Laboratory; Estados UnidosFil: Fernández Moroni, Guillermo. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Fermi National Accelerator Laboratory; Estados UnidosFil: Piegaia, Ricardo Nestor. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Física de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Física de Buenos Aires; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Física; ArgentinaFil: Senger, Matias. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Física; Argentina. Fermi National Accelerator Laboratory; Estados UnidosFil: Sofo Haro, Miguel Francisco. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Fermi National Accelerator Laboratory; Estados Unidos. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; ArgentinaFil: Stefanazzi, Leandro. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Fermi National Accelerator Laboratory; Estados UnidosFil: Tiffenberg, Javier Sebastian. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Fermi National Accelerator Laboratory; Estados UnidosFil: Uemura, Sho. Universitat Tel Aviv; Israe
SENSEI: Direct-Detection Results on sub-GeV Dark Matter from a New Skipper CCD
We present the first direct-detection search for sub-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.Fil: Barak, Liron. Universitat Tel Aviv; IsraelFil: Bloch, Itay M.. Universitat Tel Aviv; IsraelFil: Cababie, Mariano Ruben. Universidad de Buenos Aires; Argentina. Fermi National Accelerator Laboratory; Estados UnidosFil: Cancelo, Gustavo Indalecio. Fermi National Accelerator Laboratory; Estados UnidosFil: Chaplinsky, Luke. Stony Brook University; Estados UnidosFil: Chierchie, Fernando. Fermi National Accelerator Laboratory; Estados Unidos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Investigaciones en Ingeniería Eléctrica "Alfredo Desages". Universidad Nacional del Sur. Departamento de Ingeniería Eléctrica y de Computadoras. Instituto de Investigaciones en Ingeniería Eléctrica "Alfredo Desages"; ArgentinaFil: Crisler, Michael. Fermi National Accelerator Laboratory; Estados UnidosFil: Drlica Wagner, Alex. University of Chicago; Estados Unidos. Fermi National Accelerator Laboratory; Estados UnidosFil: Essig, Rouven. Stony Brook University; Estados UnidosFil: Estrada, Juan. Fermi National Accelerator Laboratory; Estados UnidosFil: Etzion, Erez. Universitat Tel Aviv; IsraelFil: Fernández Moroni, Guillermo. Fermi National Accelerator Laboratory; Estados Unidos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Investigaciones en Ingeniería Eléctrica "Alfredo Desages". Universidad Nacional del Sur. Departamento de Ingeniería Eléctrica y de Computadoras. Instituto de Investigaciones en Ingeniería Eléctrica "Alfredo Desages"; ArgentinaFil: Gift, Daniel. Stony Brook University; Estados UnidosFil: Munagavalasa, Sravan. Stony Brook University; Estados UnidosFil: Orly, Aviv. Universitat Tel Aviv; IsraelFil: Rodrigues, Dario. Fermi National Accelerator Laboratory; Estados Unidos. Universidad de Buenos Aires; ArgentinaFil: Singal, Aman. Stony Brook University; Estados UnidosFil: Sofo Haro, Miguel Francisco. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Fermi National Accelerator Laboratory; Estados Unidos. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; ArgentinaFil: Stefanazzi, Leandro. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Investigaciones en Ingeniería Eléctrica "Alfredo Desages". Universidad Nacional del Sur. Departamento de Ingeniería Eléctrica y de Computadoras. Instituto de Investigaciones en Ingeniería Eléctrica "Alfredo Desages"; Argentina. Fermi National Accelerator Laboratory; Estados UnidosFil: Tiffenberg, Javier Sebastian. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Fermi National Accelerator Laboratory; Estados UnidosFil: Uemura, Sho. Universitat Tel Aviv; IsraelFil: Volansky, Tomer. Universitat Tel Aviv; IsraelFil: Yu, Tien Tien. University of Oregon; Estados UnidosFil: SENSEI collaboration. No especifíca
SENSEI: Search for Millicharged Particles produced in the NuMI Beam
International audienceMillicharged particles appear in several extensions of the Standard Model, but have not yet been detected. These hypothetical particles could be produced by an intense proton beam striking a fixed target. We use data collected in 2020 by the SENSEI experiment in the MINOS cavern at the Fermi National Accelerator Laboratory to search for ultra-relativistic millicharged particles produced in collisions of protons in the NuMI beam with a fixed graphite target. The absence of any ionization events with 3 to 6 electrons in the SENSEI data allow us to place world-leading constraints on millicharged particles for masses between 30 MeV to 380 MeV. This work also demonstrates the potential of utilizing low-threshold detectors to investigate new particles in beam-dump experiments, and motivates a future experiment designed specifically for this purpose
SENSEI: Search for Millicharged Particles produced in the NuMI Beam
International audienceMillicharged particles appear in several extensions of the Standard Model, but have not yet been detected. These hypothetical particles could be produced by an intense proton beam striking a fixed target. We use data collected in 2020 by the SENSEI experiment in the MINOS cavern at the Fermi National Accelerator Laboratory to search for ultra-relativistic millicharged particles produced in collisions of protons in the NuMI beam with a fixed graphite target. The absence of any ionization events with 3 to 6 electrons in the SENSEI data allow us to place world-leading constraints on millicharged particles for masses between 30 MeV to 380 MeV. This work also demonstrates the potential of utilizing low-threshold detectors to investigate new particles in beam-dump experiments, and motivates a future experiment designed specifically for this purpose
SENSEI: First Direct-Detection Results on sub-GeV Dark Matter from SENSEI at SNOLAB
International audienceWe present the first results from a dark matter search using six Skipper-CCDs in the SENSEI detector operating at SNOLAB. With an exposure of 534.9 gram-days from well-performing sensors, we select events containing 2 to 10 electron-hole pairs. After aggressively masking images to remove backgrounds, we observe 55 two-electron events, 4 three-electron events, and no events containing 4 to 10 electrons. The two-electron events are consistent with pileup from one-electron events. Among the 4 three-electron events, 2 appear in pixels that are likely impacted by detector defects, although not strongly enough to trigger our "hot-pixel" mask. We use these data to set world-leading constraints on sub-GeV dark matter interacting with electrons and nuclei
SENSEI: First Direct-Detection Results on sub-GeV Dark Matter from SENSEI at SNOLAB
International audienceWe present the first results from a dark matter search using six Skipper-CCDs in the SENSEI detector operating at SNOLAB. With an exposure of 534.9 gram-days from well-performing sensors, we select events containing 2 to 10 electron-hole pairs. After aggressively masking images to remove backgrounds, we observe 55 two-electron events, 4 three-electron events, and no events containing 4 to 10 electrons. The two-electron events are consistent with pileup from one-electron events. Among the 4 three-electron events, 2 appear in pixels that are likely impacted by detector defects, although not strongly enough to trigger our "hot-pixel" mask. We use these data to set world-leading constraints on sub-GeV dark matter interacting with electrons and nuclei