407 research outputs found
Modelling of gas dynamical properties of the KATRIN tritium source and implications for the neutrino mass measurement
The KATRIN experiment aims to measure the effective mass of the electron
antineutrino from the analysis of electron spectra stemming from the beta-decay
of molecular tritium with a sensitivity of 200 meV. Therefore, a daily
throughput of about 40 g of gaseous tritium is circulated in a windowless
source section. An accurate description of the gas flow through this section is
of fundamental importance for the neutrino mass measurement as it significantly
influences the generation and transport of beta-decay electrons through the
experimental setup. In this paper we present a comprehensive model consisting
of calculations of rarefied gas flow through the different components of the
source section ranging from viscous to free molecular flow. By connecting these
simulations with a number of experimentally determined operational parameters
the gas model can be refreshed regularly according to the measured operating
conditions. In this work, measurement and modelling uncertainties are
quantified with regard to their implications for the neutrino mass measurement.
We find that the systematic uncertainties related to the description of gas
flow are represented by eV,
and that the gas model is ready to be used in the analysis of upcoming KATRIN
data.Comment: 28 pages, 13 figure
Modeling the unified measurement uncertainty of deflectometric and plenoptic 3-D sensors
In this paper we propose new models of two complementary optical sensors to
obtain 2.5-D measurements of opaque surfaces: a
deflectometric and a plenoptic sensor. The deflectometric sensor uses active
triangulation and works best on specular surfaces, while the plenoptic sensor
uses passive triangulation and works best on textured, diffusely reflecting
surfaces. We propose models to describe the measurement uncertainties of the
sensors for specularly to diffusely reflecting surfaces under consideration
of typical disturbances like ambient light or vibration. The predicted
measurement uncertainties of both sensors can be used to obtain optimized
measurements uncertainties for varying surface properties on the basis of a
combined sensor system. The models are validated exemplarily based on real
measurements.</p
Differentially Testing Soundness and Precision of Program Analyzers
In the last decades, numerous program analyzers have been developed both by
academia and industry. Despite their abundance however, there is currently no
systematic way of comparing the effectiveness of different analyzers on
arbitrary code. In this paper, we present the first automated technique for
differentially testing soundness and precision of program analyzers. We used
our technique to compare six mature, state-of-the art analyzers on tens of
thousands of automatically generated benchmarks. Our technique detected
soundness and precision issues in most analyzers, and we evaluated the
implications of these issues to both designers and users of program analyzers
Efficient Interpolation for the Theory of Arrays
Existing techniques for Craig interpolation for the quantifier-free fragment
of the theory of arrays are inefficient for computing sequence and tree
interpolants: the solver needs to run for every partitioning of the
interpolation problem to avoid creating -mixed terms. We present a new
approach using Proof Tree Preserving Interpolation and an array solver based on
Weak Equivalence on Arrays. We give an interpolation algorithm for the lemmas
produced by the array solver. The computed interpolants have worst-case
exponential size for extensionality lemmas and worst-case quadratic size
otherwise. We show that these bounds are strict in the sense that there are
lemmas with no smaller interpolants. We implemented the algorithm and show that
the produced interpolants are useful to prove memory safety for C programs.Comment: long version of the paper at IJCAR 201
Using a runway paradigm to assess the relative strength of rats' motivations for enrichment objects
Laboratory animals should be provided with enrichment objects in their cages; however, it is first necessary to
test whether the proposed enrichment objects provide benefits that increase the animalsâ welfare. The two main
paradigms currently used to assess proposed enrichment objects are the choice test, which is limited to determining
relative frequency of choice, and consumer demand studies, which can indicate the strength of a preference but are complex to design. Here, we propose a third methodology: a runway paradigm, which can be used to assess the strength of an animalâs motivation for enrichment objects, is simpler to use than consumer demand studies, and is faster to complete than typical choice tests. Time spent with objects in a standard choice test was used to rank several enrichment objects in order to compare with the ranking found in our runway paradigm. The rats ran significantly more times, ran faster, and interacted longer with objects with which they had previously spent the most time. It was concluded that this simple methodology is suitable for measuring ratsâ motivation to reach enrichment objects. This can be used to assess the preference for different types of enrichment objects or to measure reward system processes
Detergents and chaotropes for protein solubilization before two-dimensional electrophoresis
Because of the outstanding ability of two-dimensional electrophoresis to
separate complex mixtures of intact proteins, it would be advantageous to apply
it to all types of proteins, including hydrophobic and membrane proteins.
Unfortunately, poor solubility hampers the analysis of these molecules. As
these problems arise mainly in the extraction and isoelectric focusing steps,
the solution is to improve protein solubility under the conditions prevailing
during isoelectric focusing. This chapter describes the use of chaotropes and
novel detergents to enhance protein solubility during sample extraction and
isoelectric focussing, and discusses the contribution of these compounds to
improving proteomic analysis of membrane proteins
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Improved Upper Limit on the Neutrino Mass from a Direct Kinematic Method by KATRIN.
We report on the neutrino mass measurement result from the first four-week science run of the Karlsruhe Tritium Neutrino experiment KATRIN in spring 2019. Beta-decay electrons from a high-purity gaseous molecular tritium source are energy analyzed by a high-resolution MAC-E filter. A fit of the integrated electron spectrum over a narrow interval around the kinematic end point at 18.57 keV gives an effective neutrino mass square value of (-1.0_{-1.1}^{+0.9})ââeV^{2}. From this, we derive an upper limit of 1.1 eV (90% confidence level) on the absolute mass scale of neutrinos. This value coincides with the KATRIN sensitivity. It improves upon previous mass limits from kinematic measurements by almost a factor of 2 and provides model-independent input to cosmological studies of structure formation
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