8,227 research outputs found
Properties of potential eco-friendly gas replacements for particle detectors in high-energy physics
Gas detectors for elementary particles require F-based gases for optimal performance.
Recent regulations demand the use of environmentally unfriendly F-based gases to be limited or
banned. This work studies properties of potential eco-friendly gas replacements by computing the
physical and chemical parameters relevant for use as detector media, and suggests candidates to be
considered for experimental investigation
Properties of potential eco-friendly gas replacements for particle detectors in high-energy physics
Modern gas detectors for detection of particles require F-based gases for
optimal performance. Recent regulations demand the use of environmentally
unfriendly F-based gases to be limited or banned. This review studies
properties of potential eco-friendly gas candidate replacements.Comment: 38 pages, 9 figures, 8 tables. To be submitted to Journal of
Instrumentatio
Candidate eco-friendly gas mixtures for MPGDs
Modern gas detectors for detection of particles require F-based gases for optimal performance.Recent regulations demand the use of environmentally unfriendly F-based gases t o be limited or banned. This review studies properties of potential eco-friendly gas candidate replacements
Effects of urbanization on regional meteorology and air quality in Southern California
Urbanization has a profound influence on regional meteorology and air quality
in megapolitan Southern California. The influence of urbanization on
meteorology is driven by changes in land surface physical properties and land
surface processes. These changes in meteorology in turn influence air quality
by changing temperature-dependent chemical reactions and emissions,
gasâparticle phase partitioning, and ventilation of pollutants. In this study
we characterize the influence of land surface changes via historical
urbanization from before human settlement to the present day on meteorology and
air quality in Southern California using the Weather Research and Forecasting
Model coupled to chemistry and the single-layer urban canopy model
(WRFâUCMâChem). We assume identical anthropogenic emissions for the
simulations carried out and thus focus on the effect of changes in land
surface physical properties and land surface processes on air quality.
Historical urbanization has led to daytime air temperature decreases of up to
1.4 K and evening temperature increases of up to 1.7 K. Ventilation of air
in the LA basin has decreased up to 36.6 % during daytime and increased
up to 27.0 % during nighttime. These changes in meteorology are mainly
attributable to higher evaporative fluxes and thermal inertia of soil from
irrigation and increased surface roughness and thermal inertia from
buildings. Changes in ventilation drive changes in hourly
NOx concentrations with increases of up to 2.7 ppb during
daytime and decreases of up to 4.7 ppb at night. Hourly O3
concentrations decrease by up to 0.94 ppb in the morning and increase by up
to 5.6 ppb at other times of day. Changes in O3 concentrations are
driven by the competing effects of changes in ventilation and precursor
NOx concentrations. PM2.5 concentrations show slight
increases during the day and decreases of up to 2.5 ”g mâ3
at night. Process drivers for changes in PM2.5 include modifications
to atmospheric ventilation and temperature, which impact gasâparticle phase
partitioning for semi-volatile compounds and chemical reactions.
Understanding process drivers related to how land surface changes effect
regional meteorology and air quality is crucial for decision-making on urban
planning in megapolitan Southern California to achieve regional climate
adaptation and air quality improvements.</p
NASSAM: a server to search for and annotate tertiary interactions and motifs in three-dimensional structures of complex RNA molecules
Similarities in the 3D patterns of RNA base interactions or arrangements can provide insights into their functions and roles in stabilization of the RNA 3D structure. Nucleic Acids Search for Substructures and Motifs (NASSAM) is a graph theoretical program that can search for 3D patterns of base arrangements by representing the bases as pseudo-atoms. The geometric relationship of the pseudo-atoms to each other as a pattern can be represented as a labeled graph where the pseudo-atoms are the graph's nodes while the edges are the inter-pseudo-atomic distances. The input files for NASSAM are PDB formatted 3D coordinates. This web server can be used to identify matches of base arrangement patterns in a query structure to annotated patterns that have been reported in the literature or that have possible functional and structural stabilization implications. The NASSAM program is freely accessible without any login requirement at http://mfrlab.org/grafss/nassam/
Cosmic-ray strangelets in the Earth's atmosphere
If strange quark matter is stable in small lumps, we expect to find such
lumps, called ``strangelets'', on Earth due to a steady flux in cosmic rays.
Following recent astrophysical models, we predict the strangelet flux at the
top of the atmosphere, and trace the strangelets' behavior in atmospheric
chemistry and circulation. We show that several strangelet species may have
large abundances in the atmosphere; that they should respond favorably to
laboratory-scale preconcentration techniques; and that they present promising
targets for mass spectroscopy experiments.Comment: 28 pages, 4 figures, revtex
Direct Measurements of the Branching Fractions for Inclusive and Inclusive Semileptonic Decays of and Mesons
With singly-tagged samples selected from the data collected at and
around 3.773 GeV with the BESII detector at the BEPC collider, we have measured
the branching fractions for the inclusive decays of and
mesons, which are , , and
, respectively. We have also
measured the branching fractions for the inclusive semileptonic decays of
and mesons to be and . These yield the ratio of their partial
widths to be .Comment: 6 pages, 5 figure
Search for D to phi l nu and measurement of the branching fraction for D to phi pi
Using a data sample of integrated luminosity of about 33 pb collected
around 3.773 GeV with the BESII detector at the BEPC collider, the semileptonic
decays , and the hadronic
decay are studied. The upper limits of the branching
fractions are set to be 2.01% and 2.04% at the 90% confidence level. The ratio of the
branching fractions for relative to is measured to be . In addition, the
branching fraction for is obtained to be .Comment: 6 pages, 5 figures, to be published in Eur.Phys.J.
Revised experimental upper limit on the electric dipole moment of the neutron
We present for the first time a detailed and comprehensive analysis of the experimental results that set the current world sensitivity limit on the magnitude of the electric dipole moment (EDM) of the neutron. We have extended and enhanced our earlier analysis to include recent developments in the understanding of the effects of gravity in depolarizing ultracold neutrons; an improved calculation of the spectrum of the neutrons; and conservative estimates of other possible systematic errors, which are also shown to be consistent with more recent measurements undertaken with the apparatus. We obtain a net result of dn=â0.21±1.82Ă10â26ââeâcm, which may be interpreted as a slightly revised upper limit on the magnitude of the EDM of 3.0Ă10â26ââeâcm (90% C.L.) or 3.6Ă10â26ââeâcm (95% C.L.)
Measurements of branching fractions for inclusive K0~/K0 and K*(892)+- decays of neutral and charged D mesons
Using the data sample of about 33 pb-1 collected at and around 3.773 GeV with
the BES-II detector at the BEPC collider, we have studied inclusive K0~/K0 and
K*(892)+- decays of D0 and D+ mesons. The branching fractions for the inclusive
K0~/K0 and K*(892)- decays are measured to be BF(D0 to K0~/K0
X)=(47.6+-4.8+-3.0)%, BF(D+ to K0~/K0 X)=(60.5+-5.5+-3.3)%, BF(D0 to K*-
X)=(15.3+- 8.3+- 1.9)% and BF(D+ to K*- X)=(5.7+- 5.2+- 0.7)%. The upper limits
of the branching fractions for the inclusive K*(892)+ decays are set to be
BF(D0 to K*+ X)<3.6% and BF(D+ to K*+ X) <20.3% at 90% confidence level
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