The heat pulse (flash) experiment is a well-known, widely used method to determine thermal diffusivity. However, for heterogeneous, highly porous materials, neither the measurement nor the evaluation ...methodologies are straightforward. In the present paper, we focus on two open-cell carbon foam types, differing in their porosity but having the same sample size. Recent experiments showed that a non-Fourier behavior, called ’over-diffusive’ propagation, can be present for such a complex structure. The (continuum) Guyer–Krumhansl equation stands as a promising candidate to model such transient thermal behavior. In order to obtain a reliable evaluation and thus reliable thermal parameters, we utilize a novel, state-of-the-art evaluation procedure developed recently using an analytical solution of the Guyer–Krumhansl equation. Based on our observations, it turned out that the presence of high porosity alone is necessary but not satisfactory for non-Fourier behavior. Additionally, the mentioned non-Fourier effects are porosity-dependent; however, porous samples can also follow the Fourier law on a particular time scale. These data serve as a basis to properly identify the characteristic heat transfer mechanisms and their corresponding time scales, which altogether result in the present non-Fourier behavior. Based on these, we determined the validity region of Fourier’s law in respect of time scales.
The muon intensity and angular distribution in the shallow-underground laboratory Felsenkeller in Dresden, Germany have been studied using a portable muon detector based on the close cathode chamber ...design. Data has been taken at four positions in Felsenkeller tunnels VIII and IX, where a new 5 MV underground ion accelerator is being installed, and in addition at four positions in Felsenkeller tunnel IV, which hosts a low-radioactivity counting facility. At each of the eight positions studied, seven different orientations of the detector were used to compile a map of the upper hemisphere with 0.85∘ angular resolution. The muon intensity is found to be suppressed by a factor of 40 due to the 45 m thick rock overburden, corresponding to 140 m water equivalent. The angular data are matched by two different simulations taking into account the known geodetic features of the terrain: First, simply by determining the cutoff energy using the projected slant depth in rock and the known muon energy spectrum, and second, in a Geant4 simulation propagating the muons through a column of rock equal to the known slant depth. The present data are instrumental for studying muon-induced effects at these depths and also in the planning of an active veto for accelerator-based underground nuclear astrophysics experiments.
A third workshop on small-x physics, within the Small-x Collaboration, was held in Hamburg in May 2004 with the aim of overviewing recent theoretical progress in this area and summarizing the ...experimental status.
We analyze the connection between pT and multiplicity distributions in a statistical framework. We connect the Tsallis parameters, T and q, to physical properties like average energy per particle and ...the second scaled factorial moment, F2 = 〈n(n − 1)〉 / 〈n〉2, measured in multiplicity distributions. Near and far from equilibrium scenarios with master equations for the probability of having n particles, Pn, are reviewed based on hadronization transition rates, μn, from n to n + 1 particles.
In this paper we propose a method to study the functional renormalization group (FRG) at finite chemical potential. The method consists of mapping the FRG equations within the Fermi surface into a ...differential equation defined on a rectangle with zero boundary conditions. To solve this equation we use an expansion of the potential in a harmonic basis. With this method we determined the phase diagram of a simple Yukawa-type model; as expected, the bosonic fluctuations decrease the strength of the transition.
The VHMPID RICH upgrade project for ALICE at LHC Di Mauro, A.; Agocs, A.; Alfaro, R. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
05/2011, Letnik:
639, Številka:
1
Journal Article
Recenzirano
RHIC results have shown the importance of high momentum particles as hard probes and the need for particle identification (PID) in a very large momentum range. A Very High Momentum PID (VHMPID) ...detector has been proposed as upgrade of ALICE to extend the track-by-track identification capabilities for charged hadrons from the present 5
GeV/c limit to the momentum range 10–30
GeV/c. The VHMPID detector is a focusing RICH using C
4F
10 gaseous radiator coupled to a CsI-based photon detector. Detector design studies, achievable Cherenkov angle resolution, expected performance and high momentum triggering will be discussed.
Finite heat reservoir capacity, C, and temperature fluctuation, ΔT/T, lead to modifications of the well known canonical exponential weight factor. Requiring that the corrections least depend on the ...one-particle energy, ω, we derive a deformed entropy, K(S). The resultingformula contains the Boltzmann–Gibbs, Rényi, and Tsallis formulas as particular cases. For extreme large fluctuations, in the limit CΔT2/T2→∞, a new parameter-free entropy–probability relation is gained. The corresponding canonical energy distribution is nearly Boltzmannian for high probability, but for low probability approaches the cumulative Gompertz distribution. The latter is met in several phenomena, like earthquakes, demography, tumor growth models, extreme value probability, etc.
•We present a mathematical procedure to obtain a deformed entropy function.•We describe effects due to finite heat capacity and temperature fluctuations in the heat reservoir.•For the Gaussian fluctuation model the resulting entropy–probability relation recovers the traditional “log” formula.•Without temperature fluctuations (but at finite heat capacity) we obtain the Tsallis formula.•For extreme large temperature fluctuations we obtain a new “log(1−log)” formula.
Nonadditive composition rules for several physical quantities are treated in thermodynamics. It is argued that the zeroth law defines the existence of their additive forms, the formal logarithms. A ...further principle, the universal thermostat independence leads to a particular formal logarithm, equivalent to Tsallis entropy Sq. We connect q with generalized susceptibilities of the thermostat.
We present a Bayesian analysis of the Landau mass within the extended
–
model for neutron star matter. To this purpose, we consider the mass measurement of the object PSR 0740+6620, the tidal ...deformability estimation from the GW170817 and the mass-radius estimate of PSR J0030+0451 by NICER. Using Landau mass as free parameter of the theory, we tested the prediction power to find the best value for this nuclear parameter of the Bayesian method.
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