11 research outputs found
Simultaneous measurements of water optical properties by AC9 transmissometer and ASP-15 Inherent Optical Properties meter in Lake Baikal
Measurements of optical properties in media enclosing Cherenkov neutrino
telescopes are important not only at the moment of the selection of an adequate
site, but also for the continuous characterization of the medium as a function
of time. Over the two last decades, the Baikal collaboration has been measuring
the optical properties of the deep water in Lake Baikal (Siberia) where, since
April 1998, the neutrino telescope NT-200 is in operation. Measurements have
been made with custom devices. The NEMO Collaboration, aiming at the
construction of a km3 Cherenkov neutrino detector in the Mediterranean Sea, has
developed an experimental setup for the measurement of oceanographic and
optical properties of deep sea water. This setup is based on a commercial
transmissometer. During a joint campaign of the two collaborations in March and
April 2001, light absorption, scattering and attenuation in water have been
measured. The results are compatible with previous ones reported by the Baikal
Collaboration and show convincing agreement between the two experimental
techniques.Comment: 16 pages, submitted to NIM-
Sedimentation and Fouling of Optical Surfaces at the ANTARES Site
ANTARES is a project leading towards the construction and deployment of a
neutrino telescope in the deep Mediterranean Sea. The telescope will use an
array of photomultiplier tubes to detect the Cherenkov light emitted by muons
resulting from the interaction with matter of high energy neutrinos. In the
vicinity of the deployment site the ANTARES collaboration has performed a
series of in-situ measurements to study the change in light transmission
through glass surfaces during immersions of several months. The average loss of
light transmission is estimated to be only ~2% at the equator of a glass sphere
one year after deployment. It decreases with increasing zenith angle, and tends
to saturate with time. The transmission loss, therefore, is expected to remain
small for the several year lifetime of the ANTARES detector whose optical
modules are oriented downwards. The measurements were complemented by the
analysis of the ^{210}Pb activity profile in sediment cores and the study of
biofouling on glass plates. Despite a significant sedimentation rate at the
site, in the 0.02 - 0.05 cm.yr^{-1} range, the sediments adhere loosely to the
glass surfaces and can be washed off by water currents. Further, fouling by
deposits of light-absorbing particulates is only significant for surfaces
facing upwards.Comment: 18 pages, 14 figures (pdf), submitted to Astroparticle Physic
The ANTARES Optical Module
The ANTARES collaboration is building a deep sea neutrino telescope in the
Mediterranean Sea. This detector will cover a sensitive area of typically 0.1
km-squared and will be equipped with about 1000 optical modules. Each of these
optical modules consists of a large area photomultiplier and its associated
electronics housed in a pressure resistant glass sphere. The design of the
ANTARES optical module, which is a key element of the detector, has been
finalized following extensive R & D studies and is reviewed here in detail.Comment: 26 pages, 15 figures, to be published in NI
Measurements of light transmission in deep sea with the AC9 trasmissometer
The NEMO Collaboration aims to construct an underwater Cherenkov detector in the Mediterranean Sea, able to act as a neutrino telescope. One of the main tasks of this project, which implies difficult technological challenges, is the selection of an adequate marine site. In this framework the knowledge of light transmission properties in deep seawater is extremely important. The collaboration has measured optical properties in several marine sites near the Italian coasts, at depths > 3000 m, using a setup based on a AC9, a commercial trasmissometer, manufactured by WETLabs. The results obtained for the two sites reported in this paper (Alicudi and Ustica), show that deep seawater optical properties are comparable to those of the clearest waters. (C) 2002 Elsevier Science B.V. All rights reserved
Construction and test of the SM1 type Micromegas chambers for the upgrade of the ATLAS forward muon spectrometer
Large-size Resistive Micromegas have been chosen for the upgrade of the forward muon spectrometer of the ATLAS experiment, the New Small Wheel project. These chambers, together with small-strip Thin Gap Chambers (sTGC), allow reconstruction of high-momentum muon tracks in a high-radiation environment and provide a robust low-threshold single-muon trigger. A collaboration of seven INFN units built 32 SM1 type chambers, corresponding to one fourth of the total number needed for this upgrade. Each SM1 chamber has a surface of approximately 2 m(2) and four sensitive layers. The production was shared among five INFN construction sites and it was completed in fall 2020. The construction methods, as well as the results of the quality tests done on components of the detector and on the assembled chambers, are reported in the present paper
Construction and test of the SM1 type Micromegas chambers for the upgrade of the ATLAS forward muon spectrometer
Large-size Resistive Micromegas have been chosen for the upgrade of the forward muon spectrometer of the ATLAS experiment, the New Small Wheel project. These chambers, together with small-strip Thin Gap Chambers (sTGC), allow reconstruction of high-momentum muon tracks in a high-radiation environment and provide a robust low-threshold single-muon trigger. A collaboration of seven INFN units built 32 SM1 type chambers, corresponding to one fourth of the total number needed for this upgrade. Each SM1 chamber has a surface of approximately 2 m2 and four sensitive layers. The production was shared among five INFN construction sites and it was completed in fall 2020. The construction methods, as well as the results of the quality tests done on components of the detector and on the assembled chambers, are reported in the present paper
The ATLAS experiment at the CERN Large Hadron Collider: a description of the detector configuration for Run 3
Abstract
The ATLAS detector is installed in its experimental cavern
at Point 1 of the CERN Large Hadron Collider. During Run 2 of the
LHC, a luminosity of
ℒ = 2 × 1034 cm-2 s-1 was
routinely achieved at the start of fills, twice the design
luminosity. For Run 3, accelerator improvements, notably luminosity
levelling, allow sustained running at an instantaneous luminosity of
ℒ = 2 × 1034 cm-2 s-1,
with an average of up to 60 interactions per bunch crossing. The
ATLAS detector has been upgraded to recover Run 1 single-lepton
trigger thresholds while operating comfortably under Run 3 sustained
pileup conditions. A fourth pixel layer 3.3 cm from the beam axis
was added before Run 2 to improve vertex reconstruction and
b-tagging performance. New Liquid Argon Calorimeter digital
trigger electronics, with corresponding upgrades to the Trigger and
Data Acquisition system, take advantage of a factor of 10 finer
granularity to improve triggering on electrons, photons, taus, and
hadronic signatures through increased pileup rejection. The inner
muon endcap wheels were replaced by New Small Wheels with Micromegas
and small-strip Thin Gap Chamber detectors, providing both precision
tracking and Level-1 Muon trigger functionality. Trigger coverage of
the inner barrel muon layer near one endcap region was augmented
with modules integrating new thin-gap resistive plate chambers and
smaller-diameter drift-tube chambers. Tile Calorimeter scintillation
counters were added to improve electron energy resolution and
background rejection. Upgrades to Minimum Bias Trigger Scintillators
and Forward Detectors improve luminosity monitoring and enable total
proton-proton cross section, diffractive physics, and heavy ion
measurements. These upgrades are all compatible with operation in
the much harsher environment anticipated after the High-Luminosity
upgrade of the LHC and are the first steps towards preparing ATLAS
for the High-Luminosity upgrade of the LHC. This paper describes
the Run 3 configuration of the ATLAS detector.</jats:p