2,853 research outputs found
Complete list of Darboux Integrable Chains of the form
We study differential-difference equation of the form with unknown
depending on continuous and discrete variables and . Equation
of such kind is called Darboux integrable, if there exist two functions and
of a finite number of arguments , ,
, such that and , where
is the operator of total differentiation with respect to , and is
the shift operator: . Reformulation of Darboux integrability in
terms of finiteness of two characteristic Lie algebras gives an effective tool
for classification of integrable equations. The complete list of Darboux
integrable equations is given in the case when the function is of the
special form
Mn local moments prevent superconductivity in iron-pnictides Ba(Fe 1-x Mn x)2As2
75As nuclear magnetic resonance (NMR) experiments were performed on
Ba(Fe1-xMnx)2As2 (xMn = 2.5%, 5% and 12%) single crystals. The Fe layer
magnetic susceptibility far from Mn atoms is probed by the75As NMR line shift
and is found similar to that of BaFe2As2, implying that Mn does not induce
charge doping. A satellite line associated with the Mn nearest neighbours
(n.n.) of 75As displays a Curie-Weiss shift which demonstrates that Mn carries
a local magnetic moment. This is confirmed by the main line broadening typical
of a RKKY-like Mn-induced staggered spin polarization. The Mn moment is due to
the localization of the additional Mn hole. These findings explain why Mn does
not induce superconductivity in the pnictides contrary to other dopants such as
Co, Ni, Ru or K.Comment: 6 pages, 7 figure
Scintillator light yield measurements with waveform digitizers
The proton light yield of organic scintillators has been measured extensively
in recent years using fast waveform digitizers and large discrepancies exist in
the values reported by different authors. In this letter, we address principles
of digital signal processing that must be considered when conducting
scintillator light yield measurements. Digitized waveform pulse height values
are only proportional to the amount of scintillation light if the temporal
shape of the scintillation pulse is independent of the amount of energy
deposited. This is not the case for scintillation pulses resulting from fast
neutron interactions in organic scintillators. Authors measuring proton light
yield should therefore report pulse integral values and ensure that the
integration length is long enough to capture most of the scintillation light.Comment: 6 pages, 2 figure
Absolute light yield of the EJ-204 plastic scintillator
The absolute light yield of a scintillator, defined as the number of
scintillation photons produced per unit energy deposited, is a useful quantity
for scintillator development, research, and applications. Yet, literature data
on the absolute light yield of organic scintillators are limited. The goal of
this work is to assess the suitability of the EJ-204 plastic scintillator from
Eljen Technology to serve as a reference standard for measurements of the
absolute light yield of organic scintillators. Four EJ-204 samples were
examined: two manufactured approximately four months prior and stored in
high-purity nitrogen, and two aged approximately eleven years and stored in
ambient air. The scintillator response was measured using a large-area
avalanche photodiode calibrated using low energy -ray and X-ray
sources. The product of the quantum efficiency of the photodetector and light
collection efficiency of the housing was characterized using an
experimentally-benchmarked optical photon simulation. The average absolute
light yield of the fresh samples, 9100 400 photons per MeV, is lower than
the manufacturer-reported value of 10400 photons per MeV. Moreover, the aged
samples demonstrated significantly lower light yields, deviating from the
manufacturer specification by as much as 26\%. These results are consistent
with recent work showcasing environmental aging in plastic scintillators and
suggest that experimenters should use caution when deploying plastic
scintillators in photon counting applications.Comment: 12 pages, 9 figure
On the Drach superintegrable systems
Cubic invariants for two-dimensional degenerate Hamiltonian systems are
considered by using variables of separation of the associated St\"ackel
problems with quadratic integrals of motion. For the superintegrable St\"ackel
systems the cubic invariant is shown to admit new algebro-geometric
representation that is far more elementary than the all the known
representations in physical variables. A complete list of all known systems on
the plane which admit a cubic invariant is discussed.Comment: 16 pages, Latex2e+Amssym
Statistical properties of Pu, and Pu(n,) cross section calculation
The level density and gamma-ray strength function (gammaSF) of 243Pu have
been measured in the quasi-continuum using the Oslo method. Excited states in
243Pu were populated using the 242Pu(d,p) reaction. The level density closely
follows the constant-temperature level density formula for excitation energies
above the pairing gap. The gammaSF displays a double-humped resonance at low
energy as also seen in previous investigations of actinide isotopes. The
structure is interpreted as the scissors resonance and has a centroid of
omega_{SR}=2.42(5)MeV and a total strength of B_{SR}=10.1(15)mu_N^2, which is
in excellent agreement with sum-rule estimates. The measured level density and
gammaSF were used to calculate the 242Pu(n,gamma) cross section in a neutron
energy range for which there were previously no measured data.Comment: 9 pages, 8 figure
A Physicist's Proof of the Lagrange-Good Multivariable Inversion Formula
We provide yet another proof of the classical Lagrange-Good multivariable
inversion formula using techniques of quantum field theory.Comment: 9 pages, 3 diagram
Pressure as a Source of Gravity
The active mass density in Einstein's theory of gravitation in the analog of
Poisson's equation in a local inertial system is proportional to .
Here is the density of energy and its pressure for a perfect fluid.
By using exact solutions of Einstein's field equations in the static case we
study whether the pressure term contributes towards the mass
Future multimodal mobility scenarios within Europe
The European transport system faces multiple pressing challenges, including the need for significant emissions reduction in the sector and the provision of a seamless, multimodal journey to travellers. In order to address these challenges, a thorough understanding and assessment of different development pathways are required. This paper elaborates on four different scenarios developed within the scope of the Modus project. Based on these as well as additional insights from experts of the air and rail sector, initial implications for emissions reduction potential, travel times, or technological options are discussed
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