90 research outputs found
Performance Analysis Tool for HPC and Big Data Applications on Scientific Clusters
Big data is prevalent in HPC computing. Many HPC projects rely on complex workflows to analyze terabytes or petabytes of data. These workflows often require running over thousands of CPU cores and performing simultaneous data accesses, data movements, and computation. It is challenging to analyze the performance involving terabytes or petabytes of workflow data or measurement data of the executions, from complex workflows over a large number of nodes and multiple parallel task executions. To help identify performance bottlenecks or debug the performance issues in large-scale scientific applications and scientific clusters, we have developed a performance analysis framework, using state-ofthe- art open-source big data processing tools. Our tool can ingest system logs and application performance measurements to extract key performance features, and apply the most sophisticated statistical tools and data mining methods on the performance data. It utilizes an efficient data processing engine to allow users to interactively analyze a large amount of different types of logs and measurements. To illustrate the functionality of the big data analysis framework, we conduct case studies on the workflows from an astronomy project known as the Palomar Transient Factory (PTF) and the job logs from the genome analysis scientific cluster
Precision measurement of the electron energy-loss function in tritium and deuterium gas for the KATRIN experiment
The KATRIN experiment is designed for a direct and model-independent
determination of the effective electron anti-neutrino mass via a high-precision
measurement of the tritium -decay endpoint region with a sensitivity on
of 0.2eV/c (90% CL). For this purpose, the -electrons
from a high-luminosity windowless gaseous tritium source traversing an
electrostatic retarding spectrometer are counted to obtain an integral spectrum
around the endpoint energy of 18.6keV. A dominant systematic effect of the
response of the experimental setup is the energy loss of -electrons from
elastic and inelastic scattering off tritium molecules within the source. We
determined the \linebreak energy-loss function in-situ with a pulsed
angular-selective and monoenergetic photoelectron source at various
tritium-source densities. The data was recorded in integral and differential
modes; the latter was achieved by using a novel time-of-flight technique.
We developed a semi-empirical parametrization for the energy-loss function
for the scattering of 18.6-keV electrons from hydrogen isotopologs. This model
was fit to measurement data with a 95% T gas mixture at 30K, as used in
the first KATRIN neutrino mass analyses, as well as a D gas mixture of 96%
purity used in KATRIN commissioning runs. The achieved precision on the
energy-loss function has abated the corresponding uncertainty of
[arXiv:2101.05253] in the KATRIN
neutrino-mass measurement to a subdominant level.Comment: 12 figures, 18 pages; to be submitted to EPJ
Suppression of Penning discharges between the KATRIN spectrometers
The KArlsruhe TRItium Neutrino experiment (KATRIN) aims to determine the effective electron (anti)-neutrino mass with a sensitivity of 0.2eV/c by precisely measuring the endpoint region of the tritium ÎČ-decay spectrum. It uses a tandem of electrostatic spectrometers working as magnetic adiabatic collimation combined with an electrostatic (MAC-E) filters. In the space between the pre-spectrometer and the main spectrometer, creating a Penning trap is unavoidable when the superconducting magnet between the two spectrometers, biased at their respective nominal potentials, is energized. The electrons accumulated in this trap can lead to discharges, which create additional background electrons and endanger the spectrometer and detector section downstream. To counteract this problem, âelectron catchersâ were installed in the beamline inside the magnet bore between the two spectrometers. These catchers can be moved across the magnetic-flux tube and intercept on a sub-ms time scale the stored electrons along their magnetron motion paths. In this paper, we report on the design and the successful commissioning of the electron catchers and present results on their efficiency in reducing the experimental background
Quantitative Long-Term Monitoring of the Circulating Gases in the KATRIN Experiment Using Raman Spectroscopy
The Karlsruhe Tritium Neutrino (KATRIN) experiment aims at measuring the effective electron neutrino mass with a sensitivity of 0.2 eV/c, i.e., improving on previous measurements by an order of magnitude. Neutrino mass data taking with KATRIN commenced in early 2019, and after only a few weeks of data recording, analysis of these data showed the success of KATRIN, improving on the known neutrino mass limit by a factor of about two. This success very much could be ascribed to the fact that most of the system components met, or even surpassed, the required specifications during long-term operation. Here, we report on the performance of the laser Raman (LARA) monitoring system which provides continuous high-precision information on the gas composition injected into the experimentâs windowless gaseous tritium source (WGTS), specifically on its isotopic purity of tritiumâone of the key parameters required in the derivation of the electron neutrino mass. The concentrations c for all six hydrogen isotopologues were monitored simultaneously, with a measurement precision for individual components of the order 10 or better throughout the complete KATRIN data taking campaigns to date. From these, the tritium purity, ΔT, is derived with precision of <10 and trueness of <3 Ă 10, being within and surpassing the actual requirements for KATRIN, respectively
Analysis methods for the first KATRIN neutrino-mass measurement
We report on the dataset, data handling, and detailed analysis techniques of the first neutrino-mass measurement by the Karlsruhe Tritium Neutrino (KATRIN) experiment, which probes the absolute neutrino-mass scale via the ÎČ-decay kinematics of molecular tritium. The source is highly pure, cryogenic T2 gas. The ÎČ electrons are guided along magnetic field lines toward a high-resolution, integrating spectrometer for energy analysis. A silicon detector counts ÎČ electrons above the energy threshold of the spectrometer, so that a scan of the thresholds produces a precise measurement of the high-energy spectral tail. After detailed theoretical studies, simulations, and commissioning measurements, extending from the molecular final-state distribution to inelastic scattering in the source to subtleties of the electromagnetic fields, our independent, blind analyses allow us to set an upper limit of 1.1 eV on the neutrino-mass scale at a 90% confidence level. This first result, based on a few weeks of running at a reduced source intensity and dominated by statistical uncertainty, improves on prior limits by nearly a factor of two. This result establishes an analysis framework for future KATRIN measurements, and provides important input to both particle theory and cosmology
Improved eV-scale sterile-neutrino constraints from the second KATRIN measurement campaign
We present the results of the light sterile neutrino search from the second Karlsruhe Tritium Neutrino (KATRIN) measurement campaign in 2019. Approaching nominal activity, 3.76Ă106 tritium ÎČ-electrons are analyzed in an energy window extending down to 40 eV below the tritium end point at E0=18.57ââkeV. We consider the 3Îœ+1 framework with three active and one sterile neutrino flavors. The analysis is sensitive to a fourth mass eigenstate m24âČ1600ââeV2 and active-to-sterile mixing |Ue4|2âł6Ă10â3. As no sterile-neutrino signal was observed, we provide improved exclusion contours on m24 and |Ue4|2 at 95% C.L. Our results supersede the limits from the Mainz and Troitsk experiments. Furthermore, we are able to exclude the large Îm241 solutions of the reactor antineutrino and gallium anomalies to a great extent. The latter has recently been reaffirmed by the BEST Collaboration and could be explained by a sterile neutrino with large mixing. While the remaining solutions at small Îm241 are mostly excluded by short-baseline reactor experiments, KATRIN is the only ongoing laboratory experiment to be sensitive to relevant solutions at large Îm241 through a robust spectral shape analysis
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