458 research outputs found
Study of MicroPattern Gaseous detectors with novel nanodiamond based photocathodes for single photon detection in EIC RICH
Identification of high momentum hadrons at the future EIC is crucial, gaseous
RICH detectors are therefore viable option. Compact collider setups impose to
construct RICHes with small radiator length, hence significantly limiting the
number of detected photons. More photons can be detected in the far UV region,
using a windowless RICH approach. QE of CsI degrades under strong irradiation
and air contamination. Nanodiamond based photocathodes (PCs) are being
developed as an alternative to CsI. Recent development of layers of
hydrogenated nanodiamond powders as an alternative photosensitive material and
their performance, when coupled to the THick Gaseous Electron Multipliers
(THGEM)-based detectors, are the objects of an ongoing R\&D. We report about
the initial phase of our studies.Comment: 3 pages, 5 figures, RICH2018 conference proceedin
Characterization of the water diffusion in GEM foil material
Systematic studies on the GEM foil material are performed to measure the moisture diffusion rate and saturation level.These studies are important because the presence of this compound inside the detector’s foil can possibly change its mechanical and electrical properties,and in such a way,the detector performance can be affected.To understand this phenomenon,a model is developed with COMSOL Multiphysicsv.4.3 which described the adsorption and diffusion within the geometry of GEM foil,the concentration profiles and the time required to saturate the foil.The COMSOL model is verified by experimental observations on a GEM foil sample.This note will describe the model and its experimental verification results
Nanodiamond photocathodes for MPGD-based single photon detectors at future EIC
The design of a Ring Imaging CHerenkov (RICH) detector for the identification
of high momentum particles at the future Electron Ion Collider (EIC) is
extremely challenging by using current technology. Compact collider setups
impose to construct RICH with short radiator length, hence limiting the number
of generated photons. The number of detected photons can be increased by
selecting the far UV region. As standard fused-silica windows is opaque below
165 nm, a windowless RICH can be a possible approach. CsI is widely used
photocathode (PC) for photon detection in the far UV range. Due to its
hygroscopic nature it is very delicate to handle. In addition, its Quantum
Efficiency (QE) degrades in high intensity ion fluxes. These are the key
reasons to quest for novel PC with sensitivity in the far UV region. Recent
development of layers of hydrogenated nanodiamond powders as an alternative PC
material and their performance, when coupled to the THick Gaseous Electron
Multipliers (THGEM)-based detectors, are the objects of an ongoing R\&D. We
report here some preliminary results on the initial phase of these studies.Comment: 6 pages, 5 figures, MPGD-2019 La Rochelle, Proceedin
Momentum sum rules for fragmentation functions
Momentum sum rules for fragmentation functions are considered. In particular,
we give a general proof of the Sch\"afer-Teryaev sum rule for the transverse
momentum dependent Collins function. We also argue that corresponding sum rules
for related fragmentation functions do not exist. Our model-independent
analysis is supplemented by calculations in a simple field-theoretical model.Comment: 12 pages; v2: Eqs. (44,46) added, minor additional changes, to appear
in Phys. Lett.
HiCH: Hierarchical Fog-Assisted Computing Architecture for Healthcare IoT
The Internet of Things (IoT) paradigm holds significant promises for remote health monitoring systems. Due to their life-or mission-critical nature, these systems need to provide a high level of availability and accuracy. On the one hand, centralized cloud-based IoT systems lack reliability, punctuality and availability (e.g., in case of slow or unreliable Internet connection), and on the other hand, fully outsourcing data analytics to the edge of the network can result in diminished level of accuracy and adaptability due to the limited computational capacity in edge nodes. In this paper, we tackle these issues by proposing a hierarchical computing architecture, HiCH, for IoT-based health monitoring systems. The core components of the proposed system are 1) a novel computing architecture suitable for hierarchical partitioning and execution of machine learning based data analytics, 2) a closed-loop management technique capable of autonomous system adjustments with respect to patient's condition. HiCH benefits from the features offered by both fog and cloud computing and introduces a tailored management methodology for healthcare IoT systems. We demonstrate the efficacy of HiCH via a comprehensive performance assessment and evaluation on a continuous remote health monitoring case study focusing on arrhythmia detection for patients suffering from CardioVascular Diseases (CVDs)
Long term experience with perfluorobutane in COMPASS RICH
COMPASS RICH-1 has used high-purity perfluorobutane as radiator gas since
2001. The operation and control of the radiator gas has evolved over years with
continuous improvements. We report on the experience gained in the 20 year-long
operation of perfluorobutane as COMPASS RICH radiator. Very accurate values for
the radiator gas refractive index are needed for high-performance particle
identification. The procedure has evolved over years and the one presently in
use, which provides refractive index estimate at the 1 ppm level, is discussed.
Perfluorobutane procurement is becoming challenging, and the minimization of
material waste is now a priority for the protection of the environment.
Commercially available perfluorobutane needs dedicated filtering before usage
and typical material losses in the filtering procedure were around 30%. Recent
efforts allowed us to reduce them to about 5%. A potential alternative to
fluorocarbon radiators in gaseous RICHes is also presented.Comment: 4 pages, 3 figures 2 table
The high voltage system for the novel MPGD-based photon detectors of COMPASS RICH-1
The architecture of the novel MPGD-based photon detectors of COMPASS RICH-1
consists in a large-size hybrid MPGD multilayer layout combining two layers of
Thick-GEMs and a bulk resistive MICROMEGAS. Concerning biasing voltage, the
Thick-GEMs are segmented in order to reduce the energy released in case of
occasional discharges, while the MICROMEGAS anode is segmented in pads
individually biased at positive voltage, while the micromesh is grounded. In
total, there are ten different electrode types and more than 20000 electrodes
supplied by more than 100 HV channels. Commercial power supply units are used.
The original elements of the power supply system are the architecture of the
voltage distribution net, the compensation, by voltage adjustment, of the
effects of pressure and temperature variation affecting the detector gain and a
sophisticated control software, which allows to protect the detectors against
errors by the operator, to monitor and log voltages and current at 1 Hz rate
and to automatically react to detector misbehaviors. The HV system and its
performance are described in detail as well as the electrical stability of the
detector during the operation at COMPASS.Comment: 5th international conference on Micro-Pattern Gas Detectors
(MPGD2017),presentation by Silvia Dalla Torr
Fast Photon Detection for Particle Identification with COMPASS RICH-1
Particle identification at high rates is an important challenge for many
current and future high-energy physics experiments. The upgrade of the COMPASS
RICH-1 detector requires a new technique for Cherenkov photon detection at
count rates of several per channel in the central detector region, and a
read-out system allowing for trigger rates of up to 100 kHz. To cope with these
requirements, the photon detectors in the central region have been replaced
with the detection system described in this paper. In the peripheral regions,
the existing multi-wire proportional chambers with CsI photocathode are now
read out via a new system employing APV pre-amplifiers and flash ADC chips. The
new detection system consists of multi-anode photomultiplier tubes (MAPMT) and
fast read-out electronics based on the MAD4 discriminator and the F1-TDC chip.
The RICH-1 is in operation in its upgraded version for the 2006 CERN SPS run.
We present the photon detection design, constructive aspects and the first
Cherenkov light in the detector.Comment: Proceedings of the Imaging 2006 conference, Stockholm, Sweden, 27-30
June 2006, 5 pages, 6 figures, to appear in NIM A; corrected typo in caption
of Fig.
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