G. R. Araujo
A5018664154- Dark Matter and Cosmic Phenomena
- Neutrino Physics Research
- Particle physics theoretical and experimental studies
- Radiation Detection and Scintillator Technologies
- Particle Detector Development and Performance
- Atomic and Subatomic Physics Research
- Nuclear physics research studies
- Radiation Therapy and Dosimetry
- Quantum Chromodynamics and Particle Interactions
- Advanced Fluorescence Microscopy Techniques
- Astrophysics and Cosmic Phenomena
- Cell Image Analysis Techniques
- Photoacoustic and Ultrasonic Imaging
- Muon and positron interactions and applications
- Advanced Semiconductor Detectors and Materials
- Superconducting Materials and Applications
- Radioactive Decay and Measurement Techniques
- Strong Light-Matter Interactions
- Cosmology and Gravitation Theories
- Computational Physics and Python Applications
- Scientific Research and Discoveries
- Nuclear Physics and Applications
University of Zurich
2020-2024
Technical University of Munich
2019-2023
Universidade de São Paulo
2018
We present the results of a search for dark matter WIMPs in mass range below 20 GeV/c^2 using target low-radioactivity argon. The data were obtained DarkSide-50 apparatus at Laboratori Nazionali del Gran Sasso (LNGS). analysis is based on ionization signal, which time projection chamber fully efficient 0.1 keVee. observed rate detector 0.5 keVee about 1.5 events/keVee/kg/day and almost entirely accounted by known background sources. obtain 90% C.L. exclusion limit above 1.8 spin-independent...
The GERmanium Detector Array (GERDA) experiment searched for the lepton-number-violating neutrinoless double-$\beta$ ($0\nu\beta\beta$) decay of $^{76}$Ge, whose discovery would have far-reaching implications in cosmology and particle physics. By operating bare germanium diodes, enriched an active liquid argon shield, GERDA achieved unprecedently low background index $5.2\times10^{-4}$ counts/(keV$\cdot$kg$\cdot$yr) signal region met design goal to collect exposure 100 kg$\cdot$yr a...
The DarkSide-50 direct-detection dark matter experiment is a dual-phase argon time projection chamber operating at Laboratori Nazionali del Gran Sasso. This paper reports on the blind analysis of (16,660+-270) kg d exposure using target low-radioactivity extracted from underground sources. We find no events in selection box and set 90% C.L. upper limit matter-nucleon spin-independent cross section 1.14E-44 cm^2 (3.78E-44 cm^2, 3.43E-43 cm^2) for WIMP mass 100 GeV/c^2 (1 TeV/c^2, 10 TeV/c^2).
We present new constraints on sub-GeV dark matter particles scattering off electrons in argon based an analysis of ionization signal data from the DarkSide-50 detector.
DEAP-3600 is a single-phase liquid argon (LAr) direct-detection dark matter experiment, operating 2 km underground at SNOLAB (Sudbury, Canada). The detector consists of 3279 kg LAr contained in spherical acrylic vessel. This paper reports on the analysis $758\text{ }\text{ }\mathrm{tonne}\ifmmode\cdot\else\textperiodcentered\fi{}\mathrm{day}$ exposure taken over period 231 live-days during first year operation. No candidate signal events are observed WIMP-search region interest, which...
Abstract In 2015, we launched the mesoSPIM initiative, an open-source project for making light-sheet microscopy of large cleared tissues more accessible. Meanwhile, demand imaging larger samples at higher speed and resolution has increased, requiring major improvements in capabilities such microscopes. Here, introduce next-generation (“Benchtop”) with a significantly increased field view, improved resolution, throughput, affordable cost, simpler assembly compared to original version. We...
We present the measurement of two-neutrino double-β decay rate 76Ge performed with GERDA Phase II experiment. With a subset entire exposure, 11.8 kg yr, half-life process has been determined: T2ν1/2=(2.022±0.018stat±0.038syst)×1021 yr. This is most precise determination and one measurements process. The relevant nuclear matrix element can be extracted: M2νeff=(0.101±0.001).Received 13 May 2023Accepted 15 August 2023DOI:https://doi.org/10.1103/PhysRevLett.131.142501Published by American...
The DEAP-3600 experiment is searching for weakly interacting massive particles dark matter with a $\text{ }3.3\text{ }\ifmmode\times\else\texttimes\fi{}1{0}^{3}\text{kg}$ single phase liquid argon (LAr) target, located 2.1 km underground at SNOLAB. experimental signature of interactions kilo electron volt--scale $^{40}\mathrm{Ar}$ nuclear recoils producing 128 nm LAr scintillation photons observed by photomultiplier tubes. largest backgrounds in are electronic (ERs) induced...
Liquid argon-based scintillation detectors are important for dark matter searches and neutrino physics. Argon light is in the vacuum ultraviolet region, making it hard to be detected by conventional means. Polyethylene naphthalate (PEN), an optically transparent thermoplastic polyester commercially available as large area sheets or rolls, proposed alternative wavelength shifter commonly-used tetraphenyl butadiene (TPB). By combining existing literature data spectrometer measurements relative...
Abstract The specific activity of the $$\beta $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mi>β</mml:mi> </mml:math> decay $$^{39}$$ <mml:msup> <mml:mrow /> <mml:mn>39</mml:mn> </mml:msup> Ar in atmospheric argon is measured using DEAP-3600 detector. DEAP-3600, located 2 km underground at SNOLAB, uses a total (3269 ± 24) kg liquid distilled from atmosphere to search for dark matter. This detector well-suited measure owing its very low background levels. achieved two...
The GERmanium Detector Array (Gerda) collaboration searched for neutrinoless double- β decay in 76 Ge using isotopically enriched high purity germanium detectors at the Laboratori Nazionali del Gran Sasso of INFN. After Phase I (2011-2013), experiment benefited from several upgrades, including an additional active veto based on LAr instrumentation and a significant increase mass by point-contact that improved half-life sensitivity II (2015-2019) order magnitude. At core background mitigation...
Detectors based on liquid argon (LAr) often require surfaces that can shift vacuum ultraviolet (VUV) light and reflect the visible shifted light. For LAr instrumentation of LEGEND-200 neutrinoless double beta decay experiment, several square meters wavelength-shifting reflectors (WLSR) were prepared: reflector Tetratex (TTX) was in-situ evaporated with wavelength shifter tetraphenyl butadiene (TPB). even larger detectors, TPB evaporation will be more challenging plastic films polyethylene...
Abstract A search for Beyond the Standard Model double- β decay modes of 76 Ge has been performed with data collected during Phase II GERmanium Detector Array ( Gerda ) experiment, located at Laboratori Nazionali del Gran Sasso INFN (Italy). Improved limits on decays involving Majorons have obtained, compared to previous experiments Ge, half-life values order 10 23 yr. For first time Lorentz invariance violation effects in obtained. The isotropic coefficient å (3) , which embeds decay,...
Abstract The ability to detect liquid argon scintillation light from within a densely packed high-purity germanium detector array allowed the Gerda experiment reach an exceptionally low background rate in search for neutrinoless double beta decay of $${}^{76}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msup> <mml:mrow /> <mml:mn>76</mml:mn> </mml:msup> </mml:math> Ge. Proper modeling propagation throughout experimental setup, any origin volume its eventual detection by...
In 2015, we launched the mesoSPIM initiative (www.mesospim.org), an open-source project for making light-sheet microscopy of large cleared tissues more accessible. Meanwhile, demand imaging larger samples at higher speed and resolution has increased, requiring major improvements in capabilities microscopy. Here, introduce next-generation ("Benchtop") with significantly increased field view, improved resolution, throughput, affordable cost simpler assembly compared to original version. We...
LEGEND is the next-generation experiment searching for neutrinoless double beta decay in 76 Ge. The first stage, LEGEND-200, takes over cryogenic infrastructure of GERDA at LNGS: an instrumented water tank surrounding a 64 m 3 liquid argon cryostat. Around 200 kg Ge detectors will be deployed cryostat, with acting as cooling medium, high-purity passive shielding and secondary detection medium. For latter purpose, instrumentation developed, based on system used Phase II. Wavelength shifting...
The GERmanium Detector Array (GERDA) collaboration searched for neutrinoless double-$\beta$ decay in $^{76}$Ge with an array of about 40 high-purity isotopically-enriched germanium detectors. experimental signature the is a monoenergetic signal at Q$_{\beta\beta}$ = 2039.061(7)keV measured summed energy spectrum two emitted electrons. Both reconstruction and resolution detectors are crucial to separate potential from various backgrounds, such as neutrino-accompanied decays allowed by...
Neutrinoless double-$\beta$ decay of $^{76}$Ge is searched for with germanium detectors where source and detector the are identical. For success future experiments it important to increase mass detectors. We report here on characterization testing five prototype manufactured in inverted coaxial (IC) geometry from material enriched 88% $^{76}$Ge. IC combine large traditional semi-coaxial Ge superior resolution pulse shape discrimination power point contact which exhibited so far much lower...
Abstract The GERmanium Detector Array ( Gerda ) experiment operated enriched high-purity germanium detectors in a liquid argon cryostat, which contains 0.33% of $$^{36}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mmultiscripts> <mml:mrow/> <mml:mn>36</mml:mn> </mml:mmultiscripts> </mml:math> Ar, candidate isotope for the two-neutrino double-electron capture (2 $$\nu $$ <mml:mi>ν</mml:mi> ECEC) and therefore neutrinoless (0 ECEC). If detected, this process would give...
The MONUMENT experiment measures ordinary muon capture (OMC) on isotopes relevant for neutrinoless double-beta (0$\nu\beta\beta$) decay and nuclear astrophysics. OMC is a particularly attractive tool improving the theoretical description of 0$\nu\beta\beta$ decay. It involves similar momentum transfers allows testing virtual transitions involved in against experimental data. During 2021 campaign, measured $^{76}$Se $^{136}$Ba, next-generation searches, like LEGEND nEXO. setup has been...
Abstract The M onument experiment measures ordinary muon capture (OMC) on isotopes relevant for neutrinoless double-beta ( $$0\nu \beta $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mn>0</mml:mn> <mml:mi>ν</mml:mi> <mml:mi>β</mml:mi> </mml:mrow> </mml:math> ) decay and nuclear astrophysics. OMC is a particularly attractive tool improving the theoretical description of decay. It involves similar momentum transfers allows testing virtual transitions involved in...
DEAP-3600 is a liquid-argon scintillation detector looking for dark matter. Scintillation events in the liquid argon (LAr) are registered by 255 photomultiplier tubes (PMTs), and pulseshape discrimination (PSD) used to suppress electromagnetic background events. The excellent PSD performance of LAr makes it viable target matter searches, discussed here basis PSD. observed combination physics with effects. We present model energy region interest searches. composed a) physics, including...
We describe the upgrade and performance of high-purity germanium counting facility Gator, which is dedicated to low-background $\gamma$-ray spectrometry. Gator operated at Gran Sasso Underground Laboratory in Italy, an average depth 3600 meter water equivalent, employed for material screening selection ultra-low background, rare-event search experiments astroparticle physics. The detector equipped with a passive shield made layers copper, lead polyethylene, sample cavity purged gaseous...
Acrylic (poly(methyl methacrylate) or PMMA) is commonly used as a material for vessels to hold scintillating liquids in rare-event searches. Certain types of PMMA can fluoresce with low efficiency at room temperature. We have investigated the fluorescence spectra under 280 nm ultraviolet (UV) excitation DEAP-3600 dark matter search various temperatures. Fluorescence this observed, an increasing intensity sample cooled from temperature 300 K down 4 . The common wavelength-shifter tetraphenyl...