6,240 research outputs found
System Size Dependence of Particle Production at the SPS
Recent results on the system size dependence of net-baryon and hyperon
production as measured at the CERN SPS are discussed. The observed Npart
dependences of yields, but also of dynamical properties, such as average
transverse momenta, can be described in the context of the core corona
approach. Other observables, such as antiproton yields and net-protons at
forward rapidities, do not follow the predictions of this model. Possible
implications for a search for a critical point in the QCD phase diagram are
discussed. Event-by-event fluctuations of the relative core to corona source
contributions might influence fluctuation observables (e.g. multiplicity
fluctuations). The magnitude of this effect is investigated.Comment: 10 pages, 4 figurs. Proceedings of the 6th International Workshop on
Critical Point and Onset of Deconfinement in Dubna, Aug. 201
Effective renormalized multi-body interactions of harmonically confined ultracold neutral bosons
We calculate the renormalized effective 2-, 3-, and 4-body interactions for N
neutral ultracold bosons in the ground state of an isotropic harmonic trap,
assuming 2-body interactions modeled with the combination of a zero-range and
energy-dependent pseudopotential. We work to third-order in the scattering
length a defined at zero collision energy, which is necessary to obtain both
the leading-order effective 4-body interaction and consistently include
finite-range corrections for realistic 2-body interactions. The leading-order,
effective 3- and 4-body interaction energies are U3 = -(0.85576...)(a/l)^2 +
2.7921(1)(a/l)^3 + O[(a/l)^4] and U4 = +(2.43317...)(a/l)^3 + O[(a\l)^4], where
w and l are the harmonic oscillator frequency and length, respectively, and
energies are in units of hbar*w. The one-standard deviation error 0.0001 for
the third-order coefficient in U3 is due to numerical uncertainty in estimating
a slowly converging sum; the other two coefficients are either analytically or
numerically exact. The effective 3- and 4-body interactions can play an
important role in the dynamics of tightly confined and strongly correlated
systems. We also performed numerical simulations for a finite-range boson-boson
potential, and it was comparison to the zero-range predictions which revealed
that finite-range effects must be taken into account for a realistic
third-order treatment. In particular, we show that the energy-dependent
pseudopotential accurately captures, through third order, the finite-range
physics, and in combination with the multi-body effective interactions gives
excellent agreement with the numerical simulations, validating our theoretical
analysis and predictions.Comment: Updated introduction, correction of a few typos and sign error
Deciphering the silica / silane reaction mechanism for the development of a new generation of low rolling resistance tires:Part 1 – Characterization by in situ IR spectroscopy
Particle Production at the SPS and the QCD Phase Diagram
Recent results of particle production in the energy regime of the CERN-SPS
are reviewed. In order to collect information on the properties of the QCD
phase diagram systematic studies of the system size and the energy dependence
of particle production in heavy ion collisions have been performed. Net-baryon
distributions and results on strangeness production are discussed. The system
size dependence of many observables can be understood in the core-corona
approach, which has implications on the possibility to use system size as a
control parameter to study different areas of the phase diagram. Recent
attempts to search for a critical point, such as multiplicity fluctuations and
the transverse mass dependence of anti-baryon/baryon ratios are reviewed.Comment: Proccedings of 26th Winter Workshop on Nuclear Dynamics, 9 pages, 7
figure
Computation of the frequency response of a nonlinearly loaded antenna within a cavity
We analyze a nonlinearly loaded dipole antenna which is located within a rectangular cavity and excited by an electromagnetic signal. The signal is composed from two different frequencies. In order to calculate the spectrum of the resulting electromagnetic field within the resonator we transform the antenna problem into a network problem. This requires to precisely determine the antenna impedance within the cavity. The resulting nonlinear equivalent network is solved by means of the harmonic balance technique. As a result the occurrence of low intermodulation frequencies within the spectrum is verified
Non-identical particle correlation analysis as a probe of transverse flow
Non-identical two particle correlation functions probe asymmetries between
the average space-time emission points of different particle species. The
system collective expansion would produce such asymmetry because massive
particles, such as protons, are on average more pushed towards the edge of the
system, than lighter ones, i.e. pions. Measuring pion-kaon, pion-proton and
kaon-proton correlation functions, using the STAR detector, we show that the
data are consistent with the effect of transverse flow in Au-Au collisions at
GeV.Comment: 4 pages, 2 figures, 1 table, Contribution to Quark Matter 2002,
Nantes, France, July 200
Centrality and Energy Dependence of Proton, Light Fragment and Hyperon Production
Recent results of the NA49 collaboration are discussed. These include the
energy dependence of stopping and the production of the light fragments t and
3He. New data on the system size dependence of hyperon production at 40A and
158AGeV are also presented.Comment: 4 pages, Quark Matter 2006 proceeding
Practical learning method for multi-scale entangled states
We describe a method for reconstructing multi-scale entangled states from a
small number of efficiently-implementable measurements and fast
post-processing. The method only requires single particle measurements and the
total number of measurements is polynomial in the number of particles. Data
post-processing for state reconstruction uses standard tools, namely matrix
diagonalisation and conjugate gradient method, and scales polynomially with the
number of particles. Our method prevents the build-up of errors from both
numerical and experimental imperfections
Efeito de agentes de controle biológico na indução de resistência em videira.
O objetivo deste trabalho foi avaliar o efeito de agentes comerciais de controle biológico como indutores de resistência em videira para o controle do míldio
Quantification of sulfur distribution on rubber surfaces by means of μ-X-ray fluorescence analysis
A homogeneous distribution of sulfur in a rubber compound is often desired. Spatially resolved imaging techniques are useful for evaluating the distribution of this crosslinking chemical. Typical measurement methods such as SEM (scanning electron microscopy) or TEM (transmission electron microscopy) have very high resolutions. However, the sample size or the maximum area to be investigated is limited, which makes it difficult to obtain a statistically reliable determination of sulfur homogeneity across the component or sample. In this work, an alternative measurement technique is therefore presented: the μ-XRF (μ-X-ray fluorescence analysis). With the help of this method, it is possible to scan surfaces of several cm2 and to show the distribution of different chemical elements. Its measuring principle has been known for decades but has hardly been used in the rubber industry so far. The main reason for this is that its quantification process for polymeric samples is more complex than for geologic or metallic samples, which are typically been investigated with μ-XRF to date. In this paper, this issue is addressed and a solution is presented: With the help of the fundamental parameter method, the determination of sulfur homogeneity and distribution on rubber surfaces becomes possible. This opens up a variety of further possibilities for the use of μ-XRF in the rubber industry: For example, it could be used in areas of tire production, recycling of end-of-life rubber, and beyond.</p
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