284 research outputs found
A study of Ar-Nâ supercritical mixtures using neutron scattering, molecular dynamics simulations and quantum mechanical scattering calculations
The microscopic structure of Ar-Nâ supercritical mixtures was obtained using neutron scattering experiments at temperatures between 128.4 - 154.1âŻK, pressures between 48.7 - 97.8âŻbar and various mole fractions. Molecular Dynamics simulations (MD) were used to study the thermodynamics, microscopic structure and single molecule dynamics at the same conditions. The agreement between experimental and theoretical results on the intermolecular structure was very good. Furthermore, a new explicitly-correlated coupled cluster potential energy surface was obtained for the Ar-Nâ van der Waals complex. The ab initio potential energy surface (PES) was found in agreement with the MD interaction potential. The global minimum of the ab initio PES DââŻ=âŻ98.66 cmâ»Âč was located at the T-shaped geometry and at the intermolecular equilibrium distance of RââŻ=âŻ7.00aâ. The dissociation energy of the complex was determined to be DââŻ=âŻ76.86 cmâ»Âč. Quantum mechanical (QM) calculations on the newly obtained PES were used to provide the bound levels of the complex. Finally, integral and differential QM cross sections in Ar + Nâ collisions were calculated at collision energy corresponding to the average temperature of the experiments and at room temperature
An investigation of thermodynamics, microscopic structure, depolarized Rayleigh scattering, and collision dynamics in Xe-N-2 supercritical mixtures
We would like to dedicate this work to the late Professor W. A. Steele (W.A.S.), Penn State University, USA. NATO Research-Project SA 5-2-05(CRG 950087) JARC (97) 288 is acknowledged for project funding to J.S., H.V. and W.A.S. The Greek State Scholarships Foundation (IKY) is acknowledged for an award based on performance to S. M. This work was supported by computational time granted from the Greek Research & Technology Network (GRNET) in the National HPC facility ARIS. The CPU time of the Computing Centre of the University of Athens (Greece) is gratefully acknowledged. This research utilized Queen Maryâs Mid-Plus computational facilities, supported by QMUL Research-IT and funded by EPSRC grant EP/K000128/1. J.K. acknowledges financial support from the NSF Grant No. CHE-1565872 to Millard Alexander
Very Long Baseline Neutrino Oscillation Experiment for Precise Measurements of Mixing Parameters and CP Violating Effects
We analyze the prospects of a feasible, Brookhaven National Laboratory based,
very long baseline (BVLB) neutrino oscillation experiment consisting of a
conventional horn produced low energy wide band beam and a detector of 500 kT
fiducial mass with modest requirements on event recognition and resolution.
Such an experiment is intended primarily to determine CP violating effects in
the neutrino sector for 3-generation mixing. We analyze the sensitivity of such
an experiment. We conclude that this experiment will allow determination of the
CP phase and the currently unknown mixing parameter
, if , a value times
lower than the present experimental upper limit. In addition to
and , the experiment has great potential for precise measurements
of most other parameters in the neutrino mixing matrix including , , ,
and the mass ordering of neutrinos through the observation of the matter effect
in the appearance channel.Comment: 12 pages, 10 figure
Recommended from our members
PROPOSAL FOR AN EXPERIMENT PROGRAM IN NEUTRINO PHYSICS AND PROTON DECAY IN THE HOMESTAKE LABORATORY.
This report is intended to describe first, the principal physics reasons for an ambitious experimental program in neutrino physics and proton decay based on construction of a series of massive water Cherenkov detectors located deep underground (4850 ft) in the Homestake Mine of the South Dakota Science and Technology Authority (SDSTA); and second, the engineering design of the underground chambers to house the Cherenkov detector modules; and third, the conceptual design of the water Cherenkov detectors themselves for this purpose. In this proposal we show the event rates and physics sensitivity for beams from both FNAL (1300 km distant from Homestake) and BNL (2540 km distant from Homestake). The program we propose will benefit with a beam from FNAL because of the high intensities currently available from the Main Injector with modest upgrades. The possibility of tuning the primary proton energy over a large range from 30 to 120 GeV also adds considerable flexibility to the program from FNAL. On the other hand the beam from BNL over the larger distance will produce very large matter effects, and consequently a hint of new physics (beyond CP violation) can be better tested with that configuration. In this proposal we focus on the CP violation physics. Included in this document are preliminary costs and time-to-completion estimates which have been exposed to acknowledged experts in their respective areas. This presentation is not, however, to be taken as a technical design report with the extensive documentation and contingency costs that a TDR usually entails. Nevertheless, some contingency factors have been included in the estimates given here. The essential ideas expressed here were first laid out in a letter of intent to the interim director of the Homestake Laboratory on July 26, 2001. Since that time, the prospect of a laboratory in the Homestake Mine has been realized, and the design of a long baseline neutrino experiment has been refined. The extrapolation contained in this proposal is within the common domain of thinking in the area of physics discussed here. It needs now only the encouragement of the funding agencies, NSF and DOE
Higgs-Boson Decay to Four Fermions Including a Single Top Quark Below Threshold
The rare decay modes Higgs four light fermions, and Higgs
single top-quark + three light fermions for , are
presented, and phenomenologically interpreted. The angular correlation between
fermion planes is presented as a test of the spin and intrinsic parity of the
Higgs particle. In Higgs decay to single top, two tree-level graphs contribute
in the standard model (SM); one couples the Higgs to , and
one to t\bar t(\sim g_{top\;yukawa}=m_t/246\GeV). The large Yukawa coupling
for m_t>100\GeV makes the second amplitude competitive or dominant for most
values. Thus the Higgs decay rate to single top directly probes the
SM universal mechanism generating both gauge boson and fermion masses, and
offers a means to infer the Higgs- Yukawa coupling when is kinematically disallowed. We find that the modes at the SSC, and at future high energy,
high luminosity colliders, may be measureable if is not too far above
. We classify non-standard Higgses as gaugeo-phobic, fermio-phobic or
fermio-philic, and discuss the Higgs single top rates for these
classes.Comment: 30 pages, 6 figures (figures available upon request); VAND-TH-93/
A consistent treatment for pion form factors in space-like and time-like regions
We write down some relevant matrix elements for the scattering and decay
processes of the pion by considering a quark-meson vertex function. The pion
charge and transition form factors , , and
are extracted from these matrix elements using a relativistic
quark model on the light-front. We found that, the form factors and
in the space-like region agree well with experiment.
Furthermore, the branching ratios of all observed decay modes of the neutral
pion, that are related to the form factors and
in the time-like region, are all consistent with the data as
well. Additionally, in the time-like region, which deals with the
nonvalence contribution, is also discussed.Comment: 24 pages, 6 figures, to appear in Phys. Rev.
Long-Baseline Neutrino Facility (LBNF) and Deep Underground Neutrino Experiment (DUNE) Conceptual Design Report Volume 2: The Physics Program for DUNE at LBNF
The Physics Program for the Deep Underground Neutrino Experiment (DUNE) at
the Fermilab Long-Baseline Neutrino Facility (LBNF) is described
Long-Baseline Neutrino Experiment (LBNE)Conceptual Design ReportThe LBNE Water Cherenkov DetectorApril 13 2012
Conceptual Design Report (CDR) developed for the Water Cherekov Detector (WCD) option for the far detector of the Long Baseline Neutrino Experiment (LBNE
Chemical pretreatment of Arundo donax L. for second-generation ethanol production
Background: Pretreatment of lignocellulosic biomass is essential for
using it as a raw material for chemical and biofuel production. This
study evaluates the effects of variables in the chemical pretreatment
of the Arundo biomass on the glucose and xylose concentrations in the
final enzymatic hydrolysate. Three pretreatments were tested: acid
pretreatment, acid pretreatment followed by alkaline pretreatment, and
alkaline pretreatment. Results: The amounts of glucose and xylose
released by the enzymatic hydrolysis of the Arundo biomass obtained
from acid pretreatment ranged from 6.2 to 19.1 g/L and 1.8 to 3.1 g/L,
respectively. The addition of alkaline pretreatment led to a higher
yield from the enzymatic hydrolysis, with the average glucose
concentration 3.5 times that obtained after biomass hydrolysis with an
acid pretreatment exclusively. The use of an alkaline pretreatment
alone resulted in glucose and xylose concentrations similar to those
obtained in the two-step pretreatment: acid pretreatment followed by
alkaline pretreatment. There was no significant difference in
5-hydroxymethylfurfural, furfural, or acetic acid concentrations among
the pretreatments. Conclusion: Alkaline pretreatment was essential for
obtaining high concentrations of glucose and xylose. The application of
an alkaline pretreatment alone resulted in high glucose and xylose
concentrations. This result is very significant as it allows a cost
reduction by eliminating one step
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