We consider degenerate Kolmogorov–Fokker–Planck operators
L
u
=
∑
i
,
j
=
1
m
0
a
ij
(
x
,
t
)
∂
x
i
x
j
2
u
+
∑
k
,
j
=
1
N
b
jk
x
k
∂
x
j
u
-
∂
t
u
≡
∑
i
,
j
=
1
m
0
a
ij
(
x
,
t
)
∂
x
i
x
j
2
u
+
...Y
u
(with
(
x
,
t
)
∈
R
N
+
1
and
1
≤
m
0
≤
N
) such that the corresponding model operator having constant
a
ij
is hypoelliptic, translation invariant w.r.t. a Lie group operation in
R
N
+
1
and 2-homogeneous w.r.t. a family of nonisotropic dilations. The matrix
(
a
ij
)
i
,
j
=
1
m
0
is symmetric and uniformly positive on
R
m
0
. The coefficients
a
ij
are bounded and
Dini continuous in space
, and only bounded measurable in time. This means that, setting
(
i
)
S
T
=
R
N
×
-
∞
,
T
,
(
ii
)
ω
f
,
S
T
(
r
)
=
sup
(
x
,
t
)
,
(
y
,
t
)
∈
S
T
‖
x
-
y
‖
≤
r
|
f
(
x
,
t
)
-
f
(
y
,
t
)
|
(
iii
)
‖
f
‖
D
(
S
T
)
=
∫
0
1
ω
f
,
S
T
(
r
)
r
d
r
+
‖
f
‖
L
∞
S
T
we require the finiteness of
‖
a
ij
‖
D
(
S
T
)
. We bound
ω
u
x
i
x
j
,
S
T
,
‖
u
x
i
x
j
‖
L
∞
(
S
T
)
(
i
,
j
=
1
,
2
,
.
.
.
,
m
0
),
ω
Y
u
,
S
T
,
‖
Y
u
‖
L
∞
(
S
T
)
in terms of
ω
L
u
,
S
T
,
‖
L
u
‖
L
∞
(
S
T
)
and
‖
u
‖
L
∞
S
T
, getting a control on the uniform continuity in space of
u
x
i
x
j
,
Y
u
if
L
u
is bounded and Dini-continuous in space. Under the additional assumption that both the coefficients
a
ij
and
L
u
are log-Dini continuous, meaning the finiteness of the quantity
∫
0
1
ω
f
,
S
T
r
r
log
r
d
r
,
we prove that
u
x
i
x
j
and
Yu
are Dini continuous; moreover, in this case, the derivatives
u
x
i
x
j
are locally uniformly continuous in space
and time
.
This paper describes work done in the context of the Gaseous Electronics Conference (GEC) Plasma Data Exchange Project (PDEP) as discussed in the preface to this cluster issue. The purposes of this ...paper and its companion papers are to compare sets of cross sections for electron scattering from ground-state noble gas atoms in the energy range from thermal to about 1 keV and to comment on their applicability for plasma modelling. To these ends, we present in this paper intercomparisons of the nine independently derived sets of cross sections for electron scattering from ground-state argon atoms that have been posted in databases on the LXCat open-access website (www.lxcat.laplace.univ-tlse.fr). We show electron transport, excitation and ionization coefficients (swarm parameters) calculated using these cross section data in Boltzmann solvers and we compare calculated values with measurements. For the most part, the cross section sets have been compiled by co-authors on this paper and appendices giving details about how the various cross sections datasets were compiled have been written by the individual co-authors. Additional appendices discuss our criteria for selection of experimental data to be included in the comparisons and give a brief overview of the methods used here for solving the Boltzmann equation.
LXCat is an open-access website containing data needed for low temperature plasma modeling as well as on-line tools useful for their manipulation. Display omitted
► LXCat: an open-access website with ...data for low temperature plasma modeling. ► Contains compilations of electron scattering cross sections and transport data. ► Data from different contributors for many neutral, ground-state species. ► On-line tools for browsing, plotting, up/downloading data. ► On-line Boltzmann solver for calculating electron swarm parameters.
LXCat is a dynamic, open-access, website for collecting, displaying, and downloading ELECtron SCATtering cross sections and swarm parameters (mobility, diffusion coefficient, reaction rates, etc.) required for modeling low temperature, non-equilibrium plasmas. Contributors set up individual databases, and the available databases, indicated by the contributor’s chosen title, include mainly complete sets of electron-neutral scattering cross sections, although the option for introducing partial sets of cross sections exists. A database for measured swarm parameters is also part of LXCat, and this is a growing activity. On-line tools include options for browsing, plotting, and downloading cross section data. The electron energy distribution functions (edfs) in low temperature plasmas are in general non-Maxwellian, and LXCat provides an option for execution of an on-line Boltzmann equation solver to calculate the edf in homogeneous electric fields. Thus, the user can obtain electron transport and rate coefficients (averages over the edfs) in pure gases or gas mixtures over a range of values of the reduced electric fields strength, E/N, the ratio of the electric field strength to the neutral density, using cross sections from the available databases. New contributors are welcome and anyone wishing to create a database and upload data can request a username and password. LXCat is part of a larger, community-wide effort aimed at collecting, evaluating, and sharing data relevant to modeling low temperature plasmas. To illustrate the utility of LXCat in this context, we compare electron swarm parameters in argon calculated using the different compilations of cross sections presently available on LXCat. These compilations include quite different groupings of excited states, yet lead to swarm parameters in good agreement. LXCat is available at http://www.lxcat.laplace.univ-tlse.fr.
This paper is the second of a series of four reports, describing work carried in 2011 in the context of the Plasma Data Exchange Project with the Gaseous Electronics Conference, devoted to ...intercomparisons between different sets of electron-neutral scattering cross sections from ground-state noble gas atoms, in the energy range from thermal to about 1 keV. The present work compares cross section sets for helium and neon, determined independently, which are available on the open access LXCat website (www.lxcat.laplace.univ-tlse.fr/). The cross sections are used as input data in an electron Boltzmann solver or in Monte Carlo simulations, to calculate different swarm parameters (transport parameters and rate coefficients). The calculated quantities are compared with measurements to assess the quality of the cross sections in providing data for modelling low-temperature plasmas or analysing experiments. The paper includes several appendices prepared by co-authors to the work, presenting details on how the various cross section datasets were compiled or evaluated.
In this paper, a time-integrated search for point sources of cosmic neutrinos is presented using the data collected from 2007 to 2010 by the ANTARES neutrino telescope. No statistically significant ...signal has been found and upper limits on the neutrino flux have been obtained. Assuming an E super(-2) sub(v) spectrum, these flux limits are at 1-10x10 super(-8) GeV cm super(-2) s super(-1) for declinations ranging from -90degrees to 40degrees. Limits for specific models of RX J1713.7-3946 and Vela X, which include information on the source morphology and spectrum, are also given.
This paper, the third in a series of three, describes work carried in the context of Plasma Data Exchange Project of the Gaseous Electronics Conference (PDEP-GEC) to compare electron collision ...cross-sections sets from ground-state, noble gases atoms and to check their consistency with measured swarm parameters. Such consistency is a minimum requirement if the cross-section data are to be used for modelling low-temperature plasmas. In this paper, we present intercomparisons of the independently compiled sets of electron cross-sections from ground-state, neutral Kr and Xe atoms presently available on the LXCat open-access website (www.lxcat.laplace.univ-tlse.fr). Swarm parameters (reduced mobility, characteristic energy, reduced longitudinal diffusion coefficient, reduced ionization coefficient) calculated in a Boltzmann solver or Monte Carlo simulation using these cross-sections sets are compared with experimental data, also available online on the LXCat site.
A good understanding of electroluminescence is a prerequisite when optimising double-phase noble gas detectors for Dark Matter searches and high-pressure xenon TPCs for neutrinoless double beta decay ...detection.
A simulation toolkit for calculating the emission of light through electron impact on neon, argon, krypton and xenon has been developed using the Magboltz and Garfield programs. Calculated excitation and electroluminescence efficiencies, electroluminescence yield and associated statistical fluctuations are presented as a function of electric field. Good agreement with experiment and with Monte Carlo simulations has been obtained.
The calculated position resolutions for X-ray photons (1–60 keV) in pure noble gases at atmospheric pressure are presented. In this work we show the influence of the atomic shells and the detector ...dimensions on the intrinsic position resolution of the used noble gas. The calculated results were obtained by using a new software tool, Degrad, and compared to the available experimental data.
The KM3Net neutrino telescope will be composed of many optical modules, each of them containing 31 (3") photomultipliers, connected to a Central Logic Board. The Central Logic Board integrates Time ...to Digital Converters that measure Time over Threshold of the photomultipliers signals while White Rabbit is used for the optical modules time synchronization. Auxiliary boards have also been designed and built in order to test and extend the performance of the Central Logic Board. The Central Logic Board, as well as the auxiliary boards, will be presented by focusing on the design consideration, prototyping issues and tests.
The KM3NeT collaboration started to build a multi-km3neutrino telescope in the Mediterranean Sea. The telescope is composed of two parts: the ARCA detector, optimised for searches for high energy ...neutrino sources in the Universe, and ORCA, for the determination of the mass hierarchy of neutrinos. ARCA is under construction at the Capo Passero site, Italy, 80 km offshore at a depth of 3500 m while ORCA is located in the Toulon area, France, 40 km offshore at a depth of 2500 m. The basic detection element of the KM3NeT detector is the Digital Optical Module. The module is a pressure resistant glass sphere, containing 31 photo-multiplier tubes. Eighteen modules are arranged in the detection unit, a vertical structure anchored on the sea floor. The detection units are deployed on the sea bed to form a three-dimensional array of optical modules to detect Cherenkov light produced by neutrino-induced muons. In these proceedings preliminary results obtained with the first two detection units of ARCA are presented. The capability to select and reconstruct atmospheric muons is discussed. The dependence of the muon flux with the sea depth is derived, showing that the detector is well calibrated and the systematics are kept under control.
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