304 research outputs found
The ATLAS barrel level-1 Muon Trigger Sector-Logic/RX off-detector trigger and acquisition board
The ATLAS experiment uses a system of three concentric layers of Resistive Plate Chambers (RPC) detector for the Level-1 Muon Trigger in the air-core barrel toroid region. The trigger algorithm looks for hit coincidences within different detector layers inside the programmable geometrical road which defines the transverse momentum cut. The on-detector electronics that provides the trigger and detector readout functionalities collects input signals coming from the RPC front-end. Trigger and readout data are then sent via optical fibres to the off-detector electronics. Six or seven optical fibres from one of the 64 trigger sectors go to one Sector-Logic/RX module, that later elaborates the collected trigger and readout data, and sends data respectively to the Read-Out Driver modules and to the Central Level-1 Trigger. We present the functionality and the implementation of the VME Sector-Logic/RX module, and the configuration of the system for the first cosmic ray data collected using this module
Silicon Superconducting Quantum Interference Device
We have studied a Superconducting Quantum Interference SQUID device made from
a single layer thin film of superconducting silicon. The superconducting layer
is obtained by heavily doping a silicon wafer with boron atoms using the Gas
Immersion Laser Doping (GILD) technique. The SQUID device is composed of two
nano-bridges (Dayem bridges) in a loop and shows magnetic flux modulation at
low temperature and low magnetic field. The overall behavior shows very good
agreement with numerical simulations based on the Ginzburg-Landau equations.Comment: Published in Applied Physics Letters (August 2015
Radiation test and application of FPGAs in the ATLAS Level 1 Trigger
The front-end system of the Silicon Drift Detectors (SDDs) of the ALICE experiment is made of two ASICs. The first chip performs the preamplification, temporary analogue storage and analogue-to-digital conversion of the detector signals. The second chip is a digital buffer that allows for a significant reduction of the connection from the front-end module to the outside world. In this paper, the results achieved on the first complete prototype of the front-end system for the SDDs of ALICE are presented
Private costs on water conservation: study case at Cantareira Mantiqueira Corridor Region.
This study aims to evaluate the private opportunity cost for an extensive forest recover program in the Cantareira-Mantiqueira Corridor Region and discuss its results focusing on three central questions: i. what is the private opportunity cost of forest restoration for the main land use activities in the Cantareira-Mantiqueira Corridor Region? ii. how the private opportunity costs varies throughout the region? iii. What are the most cost-effectiveness PES strategies available for the Cantareira- Mantiqueira Corridor Region
First Ex-Vivo Validation of a Radioguided Surgery Technique with beta- Radiation
Purpose: A radio-guided surgery technique with beta- -emitting radio-tracers
was suggested to overcome the effect of the large penetration of gamma
radiation. The feasibility studies in the case of brain tumors and abdominal
neuro-endocrine tumors were based on simulations starting from PET images with
several underlying assumptions. This paper reports, as proof-of-principle of
this technique, an ex-vivo test on a meningioma patient. This test allowed to
validate the whole chain, from the evaluation of the SUV of the tumor, to the
assumptions on the bio-distribution and the signal detection.
Methods: A patient affected by meningioma was administered 300 MBq of
90Y-DOTATOC. Several samples extracted from the meningioma and the nearby Dura
Mater were analyzed with a beta- probe designed specifically for this
radio-guided surgery technique. The observed signals were compared both with
the evaluation from the histology and with the Monte Carlo simulation.
Results: we obtained a large signal on the bulk tumor (105 cps) and a
significant signal on residuals of 0.2 ml (28 cps). We also show that
simulations predict correctly the observed yields and this allows us to
estimate that the healthy tissues would return negligible signals (~1 cps).
This test also demonstrated that the exposure of the medical staff is
negligible and that among the biological wastes only urine has a significant
activity.
Conclusions: This proof-of-principle test on a patient assessed that the
technique is feasible with negligible background to medical personnel and
confirmed that the expectations obtained with Monte Carlo simulations starting
from diagnostic PET images are correct.Comment: 17 pages, 4 Figs, Accepted by Physica Medic
Comment on Qian et al. 2008: La Niña and El Niño composites of atmospheric CO2 change
It is well known that interannual extremes in the rate of change of atmospheric CO2 are strongly influenced by the occurrence of El Niño-Southern Oscillation (ENSO) events. Qian et al. presented ENSO composites of atmospheric CO2 changes. We show that their composites do not reflect the atmospheric changes that are most relevant to understanding the role of ENSO on atmospheric CO2 variability. We present here composites of atmospheric CO2 change that differ markedly from those of Qian et al., and reveal previously unreported asymmetries between the effects on the global carbon system of El Niño and La Niña events. The calendar-year timing differs; La Niña changes in atmospheric CO2 typically occur primarily over September–May, while El Niño changes occur primarily over December–August. And the net concentration change is quite different; La Niña changes are about half the size of El Niño changes. These results illustrate new aspects of the ENSO/global carbon budget interaction and provide useful global-scale benchmarks for the evaluation of Earth System Model studies of the carbon system
Preliminary conceptual model of the Cerro Blanco caldera-hosted geothermal system (Southern Puna, Argentina): Inferences from geochemical investigations.
The Cerro Blanco Caldera (CBC) is the youngest collapse caldera system in the Southern Central Andes (Southern
Puna, Argentina). The CBC is subsiding with at an average velocity of 0.87 cm/year and hosts an active geothermal
system. A geochemical characterization of emitted fluids was carried out based on the chemical and
isotopic compositions of fumaroles, and thermal and cold springs discharged in this volcanic area with the aim of
constructing the first hydrogeochemical conceptual model and preliminary estimate the geothermal potential.
The main hydrothermal reservoir, likely hosted within the pre-caldera basement rocks, has a Na+-Clˉ(HCO3)ˉ
composition with estimated temperatures ≥135 °C. The unconsolidated, fine-grained Cerro Blanco ignimbrite
likely acts as the cap-rock of the hydrothermal system. The presence of phreatic eruption breccias in the surrounding
area of the geothermal fumaroles supports the effectiveness of the pyroclastic deposit as sealing rocks.
The isotopic data of water (δ18O and δD) indicate a meteoric recharge of the hydrothermal reservoir, suggesting
as recharge areas the sectors surrounding the CBC, mainly towards the W and NW where large outcrops of the
pre-caldera basement exist. A fault-controlled hydraulic connection between the hot springs and the hydrothermal
reservoir is proposed for the Los Hornitos area. The fumaroles show the typical compositional features of
hydrothermal fluids, being dominated by water vapor with significant concentrations of H2S, CH4 and H2.
Considering the high geothermal gradient of this area (∼104 °C/km) and the relatively high fraction of mantle
He (∼39%) calculated on the basis of the measured R/Ra values, the hydrothermal aquifer likely receives inputs
of magmatic fluids from the degassing magma chamber. The preliminary geothermal potential at CBC was
evaluated with the Volume Method, calculating up to E = 11.4*1018 J. Both the scarce presence of superficial
thermal manifestations and the occurrence of an efficient cap-rock likely contribute to minimize the loss of
thermal energy from the reservoir. The results here presented constitute the necessary base of knowledge for
further accurate assessment of the geothermal potential and ultimately the implementation of the geothermal
resource as a viable energy alternative for small localities or mining facilities isolated from the National
Interconnected System due to their remote localization.Published1022136A. Geochimica per l'ambiente e geologia medicaJCR Journa
Portfolio selection problems in practice: a comparison between linear and quadratic optimization models
Several portfolio selection models take into account practical limitations on
the number of assets to include and on their weights in the portfolio. We
present here a study of the Limited Asset Markowitz (LAM), of the Limited Asset
Mean Absolute Deviation (LAMAD) and of the Limited Asset Conditional
Value-at-Risk (LACVaR) models, where the assets are limited with the
introduction of quantity and cardinality constraints. We propose a completely
new approach for solving the LAM model, based on reformulation as a Standard
Quadratic Program and on some recent theoretical results. With this approach we
obtain optimal solutions both for some well-known financial data sets used by
several other authors, and for some unsolved large size portfolio problems. We
also test our method on five new data sets involving real-world capital market
indices from major stock markets. Our computational experience shows that,
rather unexpectedly, it is easier to solve the quadratic LAM model with our
algorithm, than to solve the linear LACVaR and LAMAD models with CPLEX, one of
the best commercial codes for mixed integer linear programming (MILP) problems.
Finally, on the new data sets we have also compared, using out-of-sample
analysis, the performance of the portfolios obtained by the Limited Asset
models with the performance provided by the unconstrained models and with that
of the official capital market indices
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