65 research outputs found
Cross-sectional seroprevalence surveys of SARS-CoV-2 antibodies in children in Germany, June 2020 to May 2021
The rate of SARS-CoV-2 infections in children remains unclear due to many asymptomatic cases. We present a study of cross-sectional seroprevalence surveys of anti-SARS-CoV-2 IgG in 10,358 children recruited in paediatric hospitals across Germany from June 2020 to May 2021. Seropositivity increased from 2.0% (95% CI 1.6, 2.5) to 10.8% (95% CI 8.7, 12.9) in March 2021 with little change up to May 2021. Rates increased by migrant background (2.8%, 4.4% and 7.8% for no, one and two parents born outside Germany). Children under three were initially 3.6 (95% CI 2.3, 5.7) times more likely to be seropositive with levels equalising later. The ratio of seropositive cases per recalled infection decreased from 8.6 to 2.8. Since seropositivity exceeds the rate of recalled infections considerably, serologic testing may provide a more valid estimate of infections, which is required to assess both the spread and the risk for severe outcomes of SARS-CoV-2 infections
Flux Modulations seen by the Muon Veto of the GERDA Experiment
The GERDA experiment at LNGS of INFN is equipped with an active muon veto.
The main part of the system is a water Cherenkov veto with 66~PMTs in the water
tank surrounding the GERDA cryostat. The muon flux recorded by this veto shows
a seasonal modulation. Two effects have been identified which are caused by
secondary muons from the CNGS neutrino beam (2.2 %) and a temperature
modulation of the atmosphere (1.4 %). A mean cosmic muon rate of /(sm) was found in good agreement with other experiments at
LNGS at a depth of 3500~meter water equivalent.Comment: 7 pages, 6 figure
Check on the features of potted 20-inch PMTs with 1F3 electronics prototype at Pan-Asia
The Jiangmen underground neutrino observatory (JUNO) is a neutrino project
with a 20-kton liquid scintillator detector located at 700-m underground. The
large 20-inch PMTs are one of the crucial components of the JUNO experiment
aiming to precision neutrino measurements with better than 3% energy resolution
at 1 MeV. The excellent energy resolution and a large fiducial volume provide
many exciting opportunities for addressing important topics in neutrino and
astro-particle physics. With the container #D at JUNO Pan-Asia PMT testing and
potting station, the features of waterproof potted 20-inch PMTs were measured
with JUNO 1F3 electronics prototype in waveform and charge, which are valuable
for better understanding on the performance of the waterproof potted PMTs and
the JUNO 1F3 electronics. In this paper, basic features of JUNO 1F3 electronics
prototype run at Pan-Asia will be introduced, followed by an analysis of the
waterproof potted 20-inch PMTs and a comparison with the results from
commercial electronics used by the container #A and #B
Limit on the Radiative Neutrinoless Double Electron Capture of Ar from GERDA Phase I
Neutrinoless double electron capture is a process that, if detected, would
give evidence of lepton number violation and the Majorana nature of neutrinos.
A search for neutrinoless double electron capture of Ar has been
performed with germanium detectors installed in liquid argon using data from
Phase I of the GERmanium Detector Array (GERDA) experiment at the Gran Sasso
Laboratory of INFN, Italy. No signal was observed and an experimental lower
limit on the half-life of the radiative neutrinoless double electron capture of
Ar was established: 3.6 10 yr at 90 % C.I.Comment: 7 pages, 3 figure
Modeling of GERDA Phase II data
The GERmanium Detector Array (GERDA) experiment at the Gran Sasso underground
laboratory (LNGS) of INFN is searching for neutrinoless double-beta
() decay of Ge. The technological challenge of GERDA is
to operate in a "background-free" regime in the region of interest (ROI) after
analysis cuts for the full 100kgyr target exposure of the
experiment. A careful modeling and decomposition of the full-range energy
spectrum is essential to predict the shape and composition of events in the ROI
around for the search, to extract a precise
measurement of the half-life of the double-beta decay mode with neutrinos
() and in order to identify the location of residual
impurities. The latter will permit future experiments to build strategies in
order to further lower the background and achieve even better sensitivities. In
this article the background decomposition prior to analysis cuts is presented
for GERDA Phase II. The background model fit yields a flat spectrum in the ROI
with a background index (BI) of cts/(kgkeVyr) for the enriched BEGe data set and
cts/(kgkeVyr) for the
enriched coaxial data set. These values are similar to the one of Gerda Phase I
despite a much larger number of detectors and hence radioactive hardware
components
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Modeling of GERDA Phase II data
The GERmanium Detector Array (Gerda) experiment at the Gran Sasso underground laboratory (LNGS) of INFN is searching for neutrinoless double-beta (0νββ) decay of 76Ge. The technological challenge of Gerda is to operate in a “background-free” regime in the region of interest (ROI) after analysis cuts for the full 100 kg·yr target exposure of the experiment. A careful modeling and decomposition of the full-range energy spectrum is essential to predict the shape and composition of events in the ROI around Qββ for the 0νββ search, to extract a precise measurement of the half-life of the double-beta decay mode with neutrinos (2νββ) and in order to identify the location of residual impurities. The latter will permit future experiments to build strategies in order to further lower the background and achieve even better sensitivities. In this article the background decomposition prior to analysis cuts is presented for Gerda Phase II. The background model fit yields a flat spectrum in the ROI with a background index (BI) of 16.04+0.78−0.85⋅10−3 cts/(keV·kg·yr) for the enriched BEGe data set and 14.68+0.47−0.52⋅10−3 cts/(keV·kg·yr) for the enriched coaxial data set. These values are similar to the one of Phase I despite a much larger number of detectors and hence radioactive hardware components
Implementation and performances of the IPbus protocol for the JUNO Large-PMT readout electronics
The Jiangmen Underground Neutrino Observatory (JUNO) is a large neutrino
detector currently under construction in China. Thanks to the tight
requirements on its optical and radio-purity properties, it will be able to
perform leading measurements detecting terrestrial and astrophysical neutrinos
in a wide energy range from tens of keV to hundreds of MeV. A key requirement
for the success of the experiment is an unprecedented 3% energy resolution,
guaranteed by its large active mass (20 kton) and the use of more than 20,000
20-inch photo-multiplier tubes (PMTs) acquired by high-speed, high-resolution
sampling electronics located very close to the PMTs. As the Front-End and
Read-Out electronics is expected to continuously run underwater for 30 years, a
reliable readout acquisition system capable of handling the timestamped data
stream coming from the Large-PMTs and permitting to simultaneously monitor and
operate remotely the inaccessible electronics had to be developed. In this
contribution, the firmware and hardware implementation of the IPbus based
readout protocol will be presented, together with the performances measured on
final modules during the mass production of the electronics
Mass testing of the JUNO experiment 20-inch PMTs readout electronics
The Jiangmen Underground Neutrino Observatory (JUNO) is a multi-purpose,
large size, liquid scintillator experiment under construction in China. JUNO
will perform leading measurements detecting neutrinos from different sources
(reactor, terrestrial and astrophysical neutrinos) covering a wide energy range
(from 200 keV to several GeV). This paper focuses on the design and development
of a test protocol for the 20-inch PMT underwater readout electronics,
performed in parallel to the mass production line. In a time period of about
ten months, a total number of 6950 electronic boards were tested with an
acceptance yield of 99.1%
Validation and integration tests of the JUNO 20-inch PMTs readout electronics
The Jiangmen Underground Neutrino Observatory (JUNO) is a large neutrino
detector currently under construction in China. JUNO will be able to study the
neutrino mass ordering and to perform leading measurements detecting
terrestrial and astrophysical neutrinos in a wide energy range, spanning from
200 keV to several GeV. Given the ambitious physics goals of JUNO, the
electronic system has to meet specific tight requirements, and a thorough
characterization is required. The present paper describes the tests performed
on the readout modules to measure their performances.Comment: 20 pages, 13 figure
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