544 research outputs found
Assessing the effect of tsunami-induced vertical loads on RC frames
The increasing number of people, structures and economic activities being exposed to tsunami hazards
makes it important to estimate the effects of this hazard on coastal developments. Tsunami onshore
flow generates significant loading on buildings and infrastructure, which can lead to structural failure.
Literature works recently proposed a non-linear static analysis method, called Variable Depth Pushover
(VDPO), for assessing the performance of buildings under the lateral pressures induced by a tsunami
onshore flow. This methodology was developed under the assumption that the building is watertight.
However, in the case of buildings with breakaway cladding (e.g., masonry infills), the water flow passing through the building induces vertical loads on horizontal structural members, due to uplift and
buoyancy pressures, that should be considered during the analysis. Thus, to address this phenomenon,
in this paper a numerical investigation is performed considering a combination of tsunami-induced
horizontal and vertical loads on a case-study reinforced concrete (RC) moment-resisting frame with
breakaway infills, typical of Mediterranean construction. The building model is subjected to a VDPO
analysis that applies different types and sizes of vertical loading on the horizontal elements of the building, as the tsunami inundation depth increases. From the results of this analysis, the effects of tsunamiinduced vertical load components on the case-study building in terms of damage propagation and failure
mode are discussed, and the significance of considering vertical loading is proven
measuring the reading abilities of dyslexic children through a visual game
In modern society about 10% of children suffer from a neuro-developmental disorder called dyslexia, which implies difficulties in learning to read. According to recent research, playing action videogames can be a valid teaching tool to improve the reading skills of dyslexic children through forms of engagement and interaction. This paper describes the design, implementation, validation and experimentation of an educational action game oriented to promote phonological and visuo-spatial attention training in dyslexic subjects aged between 7 and 9
The Borexino detector at the Laboratori Nazionali del Gran Sasso
Borexino, a large volume detector for low energy neutrino spectroscopy, is
currently running underground at the Laboratori Nazionali del Gran Sasso,
Italy. The main goal of the experiment is the real-time measurement of sub MeV
solar neutrinos, and particularly of the mono energetic (862 keV) Be7 electron
capture neutrinos, via neutrino-electron scattering in an ultra-pure liquid
scintillator. This paper is mostly devoted to the description of the detector
structure, the photomultipliers, the electronics, and the trigger and
calibration systems. The real performance of the detector, which always meets,
and sometimes exceeds, design expectations, is also shown. Some important
aspects of the Borexino project, i.e. the fluid handling plants, the
purification techniques and the filling procedures, are not covered in this
paper and are, or will be, published elsewhere (see Introduction and
Bibliography).Comment: 37 pages, 43 figures, to be submitted to NI
Characterization of SABRE crystal NaI-33 with direct underground counting
Ultra-pure NaI(Tl) crystals are the key element for a model-independent
verification of the long standing DAMA result and a powerful means to search
for the annual modulation signature of dark matter interactions. The SABRE
collaboration has been developing cutting-edge techniques for the reduction of
intrinsic backgrounds over several years. In this paper we report the first
characterization of a 3.4 kg crystal, named NaI-33, performed in an underground
passive shielding setup at LNGS. NaI-33 has a record low K contamination
of 4.30.2 ppb as determined by mass spectrometry. We measured a light
yield of 11.10.2 photoelectrons/keV and an energy resolution of 13.2%
(FWHM/E) at 59.5 keV. We evaluated the activities of Ra and Th
inside the crystal to be Bq/kg and Bq/kg,
respectively, which would indicate a contamination from U and
Th at part-per-trillion level. We measured an activity of 0.510.02
mBq/kg due to Pb out of equilibrium and a quenching factor of
0.630.01 at 5304 keV. We illustrate the analyses techniques developed to
reject electronic noise in the lower part of the energy spectrum. A cut-based
strategy and a multivariate approach indicated a rate, attributed to the
intrinsic radioactivity of the crystal, of 1 count/day/kg/keV in the
[5-20] keV region
Characterization of SABRE crystal NaI-33 with direct underground counting
Published online: 09 April 2021Ultra-pure NaI(Tl) crystals are the key element for a model-independent verification of the long standing DAMA result and a powerful means to search for the annual modulation signature of dark matter interactions. The SABRE collaboration has been developing cutting-edge techniques for the reduction of intrinsic backgrounds over several years. In this paper we report the first characterization of a 3.4 kg crystal, named NaI-33, performed in an underground passive shielding setup at LNGS. NaI-33 has a record low ³⁹K contamination of 4.3 ± 0.2 ppb as determined by mass spectrometry. We measured a light yield of 11.1 ± 0.2 photoelectrons/keV and an energy resolution of 13.2% (FWHM/E) at 59.5 keV. We evaluated the activities of ²²⁶Ra and ²²⁸Th inside the crystal to be 5.9±0.6 μBq/kg and 1.6±0.3 μBq/kg, respectively, which would indicate a contamination from ²³⁸U and ²³²Th at part-per-trillion level. We measured an activity of 0.51 ± 0.02 mBq/kg due to ²¹⁰Pb out of equilibrium and a α quenching factor of 0.63 ± 0.01 at 5304 keV. We illustrate the analyses techniques developed to reject electronic noise in the lower part of the energy spectrum. A cut-based strategy and a multivariate approach indicated a rate, attributed to the intrinsic radioactivity of the crystal, of ∼1 count/day/kg/keV in the [5–20] keV region.M. Antonello ... I. Bolognino ... A. G. Williams ... et al
Borexino's search for low-energy neutrinos associated with gravitational wave events from GWTC-3 database
The search for neutrino events in correlation with gravitational wave (GW)
events for three observing runs (O1, O2 and O3) from 09/2015 to 03/2020 has
been performed using the Borexino data-set of the same period. We have searched
for signals of neutrino-electron scattering with visible energies above 250 keV
within a time window of 1000 s centered at the detection moment of a particular
GW event. The search was done with three visible energy thresholds of 0.25, 0.8
and 3.0 MeV.Two types of incoming neutrino spectra were considered: the
mono-energetic line and the spectrum expected from supernovae. The same spectra
were considered for electron antineutrinos detected through inverse beta-decay
(IBD) reaction. GW candidates originated by merging binaries of black holes
(BHBH), neutron stars (NSNS) and neutron star and black hole (NSBH) were
analysed separately. Additionally, the subset of most intensive BHBH mergers at
closer distances and with larger radiative mass than the rest was considered.
In total, follow-ups of 74 out of 93 gravitational waves reported in the GWTC-3
catalog were analyzed and no statistically significant excess over the
background was observed. As a result, the strongest upper limits on
GW-associated neutrino and antineutrino fluences for all flavors (\nu_e,
\nu_\mu, \nu_\tau) have been obtained in the (0.5 - 5.0) MeV neutrino energy
range.Comment: 13 pages, 8 figure
Novel techniques for alpha/beta pulse shape discrimination in Borexino
Borexino could efficiently distinguish between alpha and beta radiation in
its liquid scintillator by the characteristic time profile of their
scintillation pulse. This alpha/beta discrimination, first demonstrated at the
tonne scale in the Counting Test Facility prototype, was used throughout the
lifetime of the experiment between 2007 and 2021. With this method, alpha
events are identified and subtracted from the beta-like solar neutrino events.
This is particularly important in liquid scintillator as alpha scintillation is
quenched many-fold. In Borexino, the prominent Po-210 decay peak was a
background in the energy range of electrons scattered from Be-7 solar
neutrinos. Optimal alpha-beta discrimination was achieved with a "multi-layer
perceptron neural network", which its higher ability to leverage the timing
information of the scintillation photons detected by the photomultiplier tubes.
An event-by-event, high efficiency, stable, and uniform pulse shape
discrimination was essential in characterising the spatial distribution of
background in the detector. This benefited most Borexino measurements,
including solar neutrinos in the \pp chain and the first direct observation of
the CNO cycle in the Sun. This paper presents the key milestones in alpha/beta
discrimination in Borexino as a term of comparison for current and future large
liquid scintillator detectorsComment: 13 pages, 14 figure
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