2,010 research outputs found
Acid-base and complexing properties of some δ-hydroxyalkenylphosphine oxides
Four new compounds, asymmetrical phosphine oxides containing 2-hydroxyphenylethenyl fragment in cis-orientation with respect to the phosphine oxide: dibutyl-, diphenyl-, dibenzyl-, and dinaphthyl-2-(2-hydroxy-5- chlorophenyl)-2-phenyl-ethenylphospnine oxides, have been studied in aqueous ethanol (80 vol % of EtOH) by means of potentiometry and spectrophotometry at 25±0.1 C, and their acid-base and complexing properties estimated. © 2013 Pleiades Publishing, Ltd
Topology of energy surfaces and existence of transversal Poincar\'e sections
Two questions on the topology of compact energy surfaces of natural two
degrees of freedom Hamiltonian systems in a magnetic field are discussed. We
show that the topology of this 3-manifold (if it is not a unit tangent bundle)
is uniquely determined by the Euler characteristic of the accessible region in
configuration space. In this class of 3-manifolds for most cases there does not
exist a transverse and complete Poincar\'e section. We show that there are
topological obstacles for its existence such that only in the cases of
and such a Poincar\'e section can exist.Comment: 10 pages, LaTe
Finding a Needle in the Haystack: A Technique for Ranking Matches Between Components
Abstract. Searching and subsequently selecting reusable components from com-ponent repositories has become a key impediment for not only component-based development but also for achieving the overall usability of component develop-ment environments and the ultimate re-usability of the components themselves. Component matching, a fundamental aspect of the component search problem, has been a well-studied problem, resulting in many different matching technique
The effect of temperature induced phase transitions in aqueous solutions of triblock copolymers and Triton X-100 on the EPR, magnetic relaxation and luminescent characteristics of Gd(III) and Eu(III) ions
The present report is inspired by the idea to develop novel spectroscopy based techniques to detect the phase transitions in solutions of triblock copolymers with the use of Gd(III) and Eu(III) ions as probes. The choice of (PEO)13(PPO)30(PEO)13 (L64), (PPO)14(PEO)24(PPO)14 (17R4), (PPO)8(PEO)22(PPO)8 (10R5) and Triton X-100 is conditioned by their phase transitions occurring in mild conditions. The cloud point extraction (CPE) data reveal the conditions (pH and chelating agent) where the binding of lanthanides with surfactant rich phase of triblock copolymers and Triton X-100 occurs. The effect of phase transitions in solutions of triblock copolymers on the temperature resolved line widths in EPR spectra of Gd(III) aqua ions and transverse relaxation rates of Gd(III) inner-sphere water protons depends on the architecture of triblock copolymers and pH conditions. The steady state luminescence of Eu(III) complexes with phosphine oxide in aqueous solutions of triblock copolymers and TX-100 is influenced by the temperature induced aggregation and phase separation in solutions of reverse triblock copolymers 17R4 and 10R5, while the effect of the aggregation is insignificant for L64. © 2012 Elsevier B.V
Overview of large area triple-GEM detectors for the CMS forward muon upgrade
In order to cope with the harsh environment expected from the high luminosity LHC, the CMS forward muon system requires an upgrade. The two main challenges expected in this environment are an increase in the trigger rate and increased background radiation leading to a potential degradation of the particle ID performance. Additionally, upgrades to other subdetectors of CMS allow for extended coverage for particle tracking, and adding muon system coverage to this region will further enhance the performance of CMS
A novel application of Fiber Bragg Grating (FBG) sensors in MPGD
We present a novel application of Fiber Bragg Grating (FBG) sensors in the
construction and characterisation of Micro Pattern Gaseous Detector (MPGD),
with particular attention to the realisation of the largest triple (Gas
electron Multiplier) GEM chambers so far operated, the GE1/1 chambers of the
CMS experiment at LHC. The GE1/1 CMS project consists of 144 GEM chambers of
about 0.5 m2 active area each, employing three GEM foils per chamber, to be
installed in the forward region of the CMS endcap during the long shutdown of
LHC in 2108-2019. The large active area of each GE1/1 chamber consists of GEM
foils that are mechanically stretched in order to secure their flatness and the
consequent uniform performance of the GE1/1 chamber across its whole active
surface. So far FBGs have been used in high energy physics mainly as high
precision positioning and re-positioning sensors and as low cost, easy to
mount, low space consuming temperature sensors. FBGs are also commonly used for
very precise strain measurements in material studies. In this work we present a
novel use of FBGs as flatness and mechanical tensioning sensors applied to the
wide GEM foils of the GE1/1 chambers. A network of FBG sensors have been used
to determine the optimal mechanical tension applied and to characterise the
mechanical tension that should be applied to the foils. We discuss the results
of the test done on a full-sized GE1/1 final prototype, the studies done to
fully characterise the GEM material, how this information was used to define a
standard assembly procedure and possible future developments.Comment: 4 pages, 4 figures, presented by Luigi Benussi at MPGD 2015 (Trieste,
Italy). arXiv admin note: text overlap with arXiv:1512.0848
Development and performance of Triple-GEM detectors for the upgrade of the muon system of the CMS experiment
The CMS Collaboration is evaluating GEM detectors for the upgrade of the muon system. This contribution will focus on the R&D performed on chambers design features and will discuss the performance of the upgraded detector
Performance of a Large-Area GEM Detector Prototype for the Upgrade of the CMS Muon Endcap System
Gas Electron Multiplier (GEM) technology is being considered for the forward
muon upgrade of the CMS experiment in Phase 2 of the CERN LHC. Its first
implementation is planned for the GE1/1 system in the region of the muon endcap mainly to control muon level-1 trigger rates
after the second long LHC shutdown. A GE1/1 triple-GEM detector is read out by
3,072 radial strips with 455 rad pitch arranged in eight -sectors.
We assembled a full-size GE1/1 prototype of 1m length at Florida Tech and
tested it in 20-120 GeV hadron beams at Fermilab using Ar/CO 70:30 and
the RD51 scalable readout system. Four small GEM detectors with 2-D readout and
an average measured azimuthal resolution of 36 rad provided precise
reference tracks. Construction of this largest GEM detector built to-date is
described. Strip cluster parameters, detection efficiency, and spatial
resolution are studied with position and high voltage scans. The plateau
detection efficiency is [97.1 0.2 (stat)]\%. The azimuthal resolution is
found to be [123.5 1.6 (stat)] rad when operating in the center of
the efficiency plateau and using full pulse height information. The resolution
can be slightly improved by 10 rad when correcting for the bias due
to discrete readout strips. The CMS upgrade design calls for readout
electronics with binary hit output. When strip clusters are formed
correspondingly without charge-weighting and with fixed hit thresholds, a
position resolution of [136.8 2.5 stat] rad is measured, consistent
with the expected resolution of strip-pitch/ = 131.3 rad. Other
-sectors of the detector show similar response and performance.Comment: 8 pages, 32 figures, submitted to Proc. 2014 IEEE Nucl. Sci.
Symposium, Seattle, WA, reference adde
Charged particle detection performance of Gas Electron Multiplier (GEM) detectors for the upgrade of CMS endcap muon system at the CERN LHC
The Compact Muon Solenoid (CMS) detector is one of the two general-purpose detectors at the CERN LHC. LHC will provide exceptional high instantaneous and integrated luminosity after second long shutdown. The forward region |η| ≥ 1:5 of CMS detector will face extremely high particle rates in tens of kHz/cm2 and hence it will affect the momentum resolution, efficiency and longevity of the muon detectors. Here, η is pseudorapidity defined as η = -ln(tan(θ/2)), where θ is the polar angle measured from z-axis. To overcome these issues the CMSGEM collaboration has proposed to install new large size rate capable Triple Gas Electron Multiplier (GEM) detectors in the forward region of CMS muon system. The first set of Triple GEM detectors will be installed in the GE1/1 region (1:6 <; |η| <; 2.2) of the muon endcap during the long shutdown 2 (LS2) of the LHC. Towards this goal, full size CMS Triple GEM detectors have been fabricated and tested at the CERN SPS, H2 and H4 test beam facility. The GEM detectors were operated with two gas mixtures: Ar/CO2 (70/30) and Ar/CO2/CF4 (45/15/40). In 2014, good quality data was collected during test beam campaigns. In this paper, the performance of the detectors is summarized based on their tracking efficiency and time resolution
Design of a constant fraction discriminator for the VFAT3 front-end ASIC of the CMS GEM detector
In this work the design of a constant fraction discriminator (CFD) to be used in the VFAT3 chip for the read-out of the triple-GEM detectors of the CMS experiment, is described. A prototype chip containing 8 CFDs was implemented using 130 nm CMOS technology and test results are shown. © CERN 2016
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