An experimental evaluation of the transmission of shock waves from a detonating gas mixture in a 0.5-in-inner-diameter open-ended tube into an inert atmosphere is described in this paper. ...Stoichiometric H
2
/O
2
at 1 atm was used as the reactive gas medium. Results from in-tube diagnostics indicated successful deflagration-to-detonation transition (DDT), which leads to an overdriven detonation before exiting the tube at near Chapman–Jouguet (CJ) conditions. Out-of-tube diagnostics characterized the transmission of the shock wave into the surrounding environment, where the shock wave decays into an acoustic wave as it travels away from the tube exit. A mathematical treatment of overpressure and time-of-arrival data allowed for a direct analytical description of the transmitted shock wave’s transient velocity. This description is combined with a first-principles gas-dynamics treatment of the moving normal shock wave to describe the conditions behind the attenuating shock wave. This work furthers the understanding of shock transmission from an open-ended detonation tube and provides a theoretical framework to estimate the resulting conditions.
Since the discovery of neutrino oscillations, we know that neutrinos have non-zero mass. However, the absolute neutrino-mass scale remains unknown. Here we report the upper limits on effective ...electron anti-neutrino mass, $m_ν$, from the second physics run of the Karlsruhe Tritium Neutrino experiment. In this experiment, $m_ν$ is probed via a high-precision measurement of the tritium β-decay spectrum close to its endpoint. This method is independent of any cosmological model and does not rely on assumptions whether the neutrino is a Dirac or Majorana particle. By increasing the source activity and reducing the background with respect to the first physics campaign, we reached a sensitivity on $m_v$ of ${\text{0.7eV}c^{-2}}$ at a 90% confidence level (CL). The best fit to the spectral data yields $m\frac{2}{v}=\text{(0.26 ± 0.34)eV}^2c^{-4}$, resulting in an upper limit of $m_v{\text{<0.9eV}}c^{-2}$at 90% CL. By combining this result with the first neutrino-mass campaign, we find an upper limit of mν$m_v{\text{<0.8eV}}c^{-2}$ at 90% CL.
Since the discovery of neutrino oscillations, we know that neutrinos have non-zero mass. However, the absolute neutrino-mass scale remains unknown. Here we report the upper limits on effective ...electron anti-neutrino mass, mν, from the second physics run of the Karlsruhe Tritium Neutrino experiment. In this experiment, mν is probed via a high-precision measurement of the tritium β-decay spectrum close to its endpoint. This method is independent of any cosmological model and does not rely on assumptions whether the neutrino is a Dirac or Majorana particle. By increasing the source activity and reducing the background with respect to the first physics campaign, we reached a sensitivity on mν</sub of 0.7 eV c–2 at a 90% confidence level (CL). The best fit to the spectral data yields m$^2_ν$ = (0.26 ± 0.34) eV2 c–4, resulting in an upper limit of mν < 0.9 eV c–2 at 90% CL. By combining this result with the first neutrino-mass campaign, we find an upper limit of mν < 0.8 eV c–2 at 90% CL.
The KArlsruhe TRItium Neutrino experiment (KATRIN) aims to determine the effective electron (anti)-neutrino mass with a sensitivity of 0.2eV/c \(^2\) by precisely measuring the endpoint region of the ...tritium \(\beta \) -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, “electron catchers” 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.
The trigger system for the AUGER fluorescence detector is presented. The main goals of the design were low price, high flexibility of the trigger, high reliability and good testability even at remote ...operation. The simulation of all boards using VHDL tools resulted in a design which is optimal with respect to these goals and highly independent of existing commercial solutions. The large-scale integration of modern FPGAs yielded a massive parallel system for recognition of tracks and suppression of background. The readout and control is carried out by low cost PCs under the LINUX operating system.
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 \(\beta\)-decay ...endpoint region with a sensitivity on \(m_\nu\) of 0.2\(\,\)eV/c\(^2\) (90% CL). For this purpose, the \(\beta\)-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 18.6\(\,\)keV. A dominant systematic effect of the response of the experimental setup is the energy loss of \(\beta\)-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\(_2\) gas mixture at 30\(\,\)K, as used in the first KATRIN neutrino mass analyses, as well as a D\(_2\) gas mixture of 96% purity used in KATRIN commissioning runs. The achieved precision on the energy-loss function has abated the corresponding uncertainty of \(\sigma(m_\nu^2)<10^{-2}\,\mathrm{eV}^2\) arXiv:2101.05253 in the KATRIN neutrino-mass measurement to a subdominant level.
The KArlsruhe TRItium Neutrino experiment (KATRIN) aims to determine the effective electron (anti)neutrino mass with a sensitivity of \(0.2\textrm{ eV/c}^2\) (90\(\%\) C.L.) by precisely measuring ...the endpoint region of the tritium \(\beta\)-decay spectrum. It uses a tandem of electrostatic spectrometers working as MAC-E (magnetic adiabatic collimation combined with an electrostatic) filters. In the space between the pre-spectrometer and the main spectrometer, an unavoidable Penning trap is created 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, "electron catchers" 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.
Our group at KIT has been developing data acquisition (DAQ) systems for many years mainly for large physics experiments like the KATRIN neutrino experiment or the Pierre Auger cosmic ray observatory. ...The DAQ systems were continuously enhanced as new technologies became available. The core of the DAQ systems are field programmable gate arrays (FPGAs). Trigger functions running on the FPGAs select relevant events out of the permanent data stream of the ADCs and pass it over PCI bus to a embedded Linux computer for further analysis and storage. Modern experiments have raising requirements in both data rate and complexity of trigger and analysis function. To achieve a flexible and fast data link we developed a PCI to PCI Express (PCIe) adapter board which can be connected to any PC equipped with a standard PCIe plug-in adapter. We use this adapter to replace the embedded Linux system and to connect external GPU servers directly to the DAQ system. With this powerful data processing facility at the end of the data chain we can run complex third level trigger functions, reconstruction algorithms and analysis calculations. With PCIe as fast data link and GPU computing together with the well established FPGA unit we achieved a substantial enhancement of our DAQ system.
Design of the trigger system for the Auger fluorescence detector Gemmeke, H.; Grindler, A.; Keim, H. ...
1999 IEEE Conference on Real-Time Computer Applications in Nuclear Particle and Plasma Physics. 11th IEEE NPSS Real Time Conference. Conference Record (Cat. No.99EX295),
1999
Conference Proceeding
A description of the trigger system for the 13 200 channels of the Auger fluorescence detector is presented. The concept for the front-end electronics, the first and second level trigger, the data ...flow and the data processing rests upon the system requirements. The design uses FPGAs to obtain a cost-effective and flexible solution whenever possible. The large scale integration of the modern FPGA allowed a massive parallel solution for recognition of tracks and suppression of background. The supervision task and readout is carried out by low cost PCs under LINUX operating system.
Escherichia coli K-12 W3110 grows in the presence of membrane-permeant organic acids that can depress cytoplasmic pH and accumulate in the cytoplasm. We conducted experimental evolution by daily ...diluting cultures in increasing concentrations of benzoic acid (up to 20 mM) buffered at external pH 6.5, a pH at which permeant acids concentrate in the cytoplasm. By 2,000 generations, clones isolated from evolving populations showed increasing tolerance to benzoate but were sensitive to chloramphenicol and tetracycline. Sixteen clones grew to stationary phase in 20 mM benzoate, whereas the ancestral strain W3110 peaked and declined. Similar growth occurred in 10 mM salicylate. Benzoate-evolved strains grew like W3110 in the absence of benzoate, in media buffered at pH 4.8, pH 7.0, or pH 9.0, or in 20 mM acetate or sorbate at pH 6.5. Genomes of 16 strains revealed over 100 mutations, including single-nucleotide polymorphisms (SNPs), large deletions, and insertion knockouts. Most strains acquired deletions in the benzoate-induced multiple antibiotic resistance (Mar) regulon or in associated regulators such as rob and cpxA, as well as the multidrug resistance (MDR) efflux pumps emrA, emrY, and mdtA Strains also lost or downregulated the Gad acid fitness regulon. In 5 mM benzoate or in 2 mM salicylate (2-hydroxybenzoate), most strains showed increased sensitivity to the antibiotics chloramphenicol and tetracycline; some strains were more sensitive than a marA knockout strain. Thus, our benzoate-evolved strains may reveal additional unknown drug resistance components. Benzoate or salicylate selection pressure may cause general loss of MDR genes and regulators.
Benzoate is a common food preservative, and salicylate is the primary active metabolite of aspirin. In the gut microbiome, genetic adaptation to salicylate may involve loss or downregulation of inducible multidrug resistance systems. This discovery implies that aspirin therapy may modulate the human gut microbiome to favor salicylate tolerance at the expense of drug resistance. Similar aspirin-associated loss of drug resistance might occur in bacterial pathogens found in arterial plaques.
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