1,344 research outputs found
The neuroanatomical and neurochemical basis of apathy and impulsivity in frontotemporal lobar degeneration.
Apathy and impulsivity are common and often coexistent consequences of frontotemporal lobar degeneration (FTLD). They increase patient morbidity and carer distress, but remain under-estimated and poorly treated. Recent trans-diagnostic approaches that span the spectrum of clinical presentations of FTLD and parkinsonism, indicate that apathy and impulsivity can be fractionated into multiple neuroanatomical and pharmacological systems. These include ventral/dorsal fronto-striatal circuits for reward-sensitivity, response-inhibition, and decision-making; moderated by noradrenaline, dopamine, and serotonin. Improved assessment tools, formal models of cognition and behavior, combined with brain imaging and psycho-pharmacology, are creating new therapeutic targets and establishing principles for stratification in future clinical trials
Fiber Bragg Grating sensors for deformation monitoring of GEM foils in HEP detectors
Fiber Bragg Grating (FBG) sensors have been so far mainly used in high energy
physics (HEP) as high precision positioning and re-positioning sensors and as
low cost, easy to mount, radiation hard and low space- consuming temperature
and humidity devices. FBGs are also commonly used for very precise strain
measurements. In this work we present a novel use of FBGs as flatness and
mechanical tensioning sensors applied to the wide Gas Electron Multiplier (GEM)
foils of the GE1/1 chambers of the Compact Muon Solenoid (CMS) experiment at
Large Hadron Collider (LHC) of CERN. A network of FBG sensors has been used to
determine the optimal mechanical tension applied and to characterize the
mechanical stress applied to the foils. The preliminary results of the test
performed on a full size GE1/1 final prototype and possible future developments
will be discussed.Comment: Four pages, seven figures. Presented by Michele Caponero at IWASI
2015, Gallipoli (Italy
Eco-friendly gas mixtures for Resistive Plate Chambers based on Tetrafluoropropene and Helium
Due to the recent restrictions deriving from the application of the Kyoto
protocol, the main components of the gas mixtures presently used in the
Resistive Plate Chambers systems of the LHC experiments will be most probably
phased out of production in the coming years. Identifying possible replacements
with the adequate characteristics requires an intense R&D, which was recently
started, also in collaborations across the various experiments. Possible
candidates have been proposed and are thoroughly investigated. Some tests on
one of the most promising candidate - HFO-1234ze, an allotropic form of
tetrafluoropropane- have already been reported. Here an innovative approach,
based on the use of Helium, to solve the problems related to the too elevate
operating voltage of HFO-1234ze based gas mixtures, is discussed and the
relative first results are shown.Comment: 9 pages, 6 figures, 1 tabl
Cms gem detector material study for the hl-lhc
A study on the Gaseous Electron Multiplier (GEM) foil material is performed to determine the moisture diffusion rate, moisture saturation level and the effects on its mechanical properties. The study is focused on the foil contact with ambient air and moisture to determine the value of the diffusion coefficient of water in the foil material. The presence of water inside the detector foil can determine the changes in its mechanical and electrical properties. A simulated model is developed with COMSOL Multiphysics v. 4.3 [1] by taking into account the real GEM foil (hole dimensions, shapes and material), which describes the adsorption of water. This work describes the model, its experimental verification, the water diffusion within the entire sheet geometry of the GEM foil, thus gaining concentration profiles and the time required to saturate the system and the effects on the mechanical properties
A 1 m Gas Time Projection Chamber with Optical Readout for Directional Dark Matter Searches: the CYGNO Experiment
The aim of the CYGNO project is the construction and operation of a 1~m
gas TPC for directional dark matter searches and coherent neutrino scattering
measurements, as a prototype toward the 100-1000~m (0.15-1.5 tons) CYGNUS
network of underground experiments. In such a TPC, electrons produced by
dark-matter- or neutrino-induced nuclear recoils will drift toward and will be
multiplied by a three-layer GEM structure, and the light produced in the
avalanche processes will be readout by a sCMOS camera, providing a 2D image of
the event with a resolution of a few hundred micrometers. Photomultipliers will
also provide a simultaneous fast readout of the time profile of the light
production, giving information about the third coordinate and hence allowing a
3D reconstruction of the event, from which the direction of the nuclear recoil
and consequently the direction of the incoming particle can be inferred. Such a
detailed reconstruction of the event topology will also allow a pure and
efficient signal to background discrimination. These two features are the key
to reach and overcome the solar neutrino background that will ultimately limit
non-directional dark matter searches.Comment: 5 page, 7 figures, contribution to the Conference Records of 2018
IEEE NSS/MI
A study of gas contaminants and interaction with materials in RPC closed loop systems
Resistive Plate Counters (RPC) detectors at the Large Hadron Collider (LHC)
experiments use gas recirculation systems to cope with large gas mixture
volumes and costs. In this paper a long-term systematic study about gas
purifiers, gas contaminants and detector performance is discussed. The study
aims at measuring the lifetime of purifiers with unused and used cartridge
material along with contaminants release in the gas system. During the
data-taking the response of several RPC double-gap detectors was monitored in
order to characterize the correlation between dark currents, filter status and
gas contaminants
An analysis of materials used in the RPC detector and in the closed loop gas system of CMS at the LHC.
The results are reported of the study of materials used in the CERN Closed Loop recirculation
gas system currently under test with the RPC muon detectors in the CMS experiment
at the LHC. Studies include a sampling campaign in a low-radiation environment (cosmic
rays at the CERN ISR test site). We describe the dedicated RPC chamber tests, the
chemical analysis of the filters and gas used, and discuss the results of the Closed Loop
system
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