86 research outputs found
Accurate reference gas mixtures containing tritiated molecules: Their production and ramanâbased analysis
Highly accurate, quantitative analyses of mixtures of hydrogen isotopologuesâboth the stable species, H, D2, and HD, and the radioactive species, T, HT, and DTâare of great importance in fields as diverse as deuteriumâtritium fusion, neutrino mass measurements using tritium ÎČ-decay, or for photonuclear experiments in which hydrogenâdeuterium targets are used. In this publication we describe a production, handling, and analysis facility capable of fabricating well-defined gas samples, which may contain any of the stable and radioactive hydrogen isotopologues, with sub-percent accuracy for the relative species concentrations. The production is based on precise manometric gas mixing of H, D, and T. The heteronuclear isotopologues HD, HT, and DT are generated via controlled, in-line catalytic reaction or by ÎČ-induced self-equilibration, respectively. The analysis was carried out using an in-line intensity- and wavelength-calibrated Raman spectroscopy system. This allows for continuous monitoring of the composition of the circulating gas during the self-equilibration or catalytic evolution phases. During all procedures, effects, such as exchange reactions with wall materials, were considered with care. Together with measurement statistics, these and other systematic effects were included in the determination of composition uncertainties of the generated reference gas samples. Measurement and calibration accuracy at the level of 1% was achieved
Commissioning of the vacuum system of the KATRIN Main Spectrometer
The KATRIN experiment will probe the neutrino mass by measuring the
beta-electron energy spectrum near the endpoint of tritium beta-decay. An
integral energy analysis will be performed by an electro-static spectrometer
(Main Spectrometer), an ultra-high vacuum vessel with a length of 23.2 m, a
volume of 1240 m^3, and a complex inner electrode system with about 120000
individual parts. The strong magnetic field that guides the beta-electrons is
provided by super-conducting solenoids at both ends of the spectrometer. Its
influence on turbo-molecular pumps and vacuum gauges had to be considered. A
system consisting of 6 turbo-molecular pumps and 3 km of non-evaporable getter
strips has been deployed and was tested during the commissioning of the
spectrometer. In this paper the configuration, the commissioning with bake-out
at 300{\deg}C, and the performance of this system are presented in detail. The
vacuum system has to maintain a pressure in the 10^{-11} mbar range. It is
demonstrated that the performance of the system is already close to these
stringent functional requirements for the KATRIN experiment, which will start
at the end of 2016.Comment: submitted for publication in JINST, 39 pages, 15 figure
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
New Constraint on the Local Relic Neutrino Background Overdensity with the First KATRIN Data Runs
We report on the direct cosmic relic neutrino background search from the
first two science runs of the KATRIN experiment in 2019. Beta-decay electrons
from a high-purity molecular tritium gas source are analyzed by a
high-resolution MAC-E filter around the kinematic endpoint at 18.57 keV. The
analysis is sensitive to a local relic neutrino overdensity of 9.7e10 (1.1e11)
at a 90% (95%) confidence level. A fit of the integrated electron spectrum over
a narrow interval around the kinematic endpoint accounting for relic neutrino
captures in the Tritium source reveals no significant overdensity. This work
improves the results obtained by the previous kinematic neutrino mass
experiments at Los Alamos and Troitsk. We furthermore update the projected
final sensitivity of the KATRIN experiment to <1e10 at 90% confidence level, by
relying on updated operational conditions.Comment: 7 pages, 7 figure
Reduction of stored-particle background by a magnetic pulse method at the KATRIN experiment
The KATRIN experiment aims to determine the effective electron neutrino mass with a sensitivity of 0.2 eV/c2 (%90 CL) by precision measurement of the shape of the tritium ÎČ-spectrum in the endpoint region. The energy analysis of the decay electrons is achieved by a MAC-E filter spectrometer. A common background source in this setup is the decay of short-lived isotopes, such as 219Rn and 220Rn, in the spectrometer volume. Active and passive countermeasures have been implemented and tested at the KATRIN main spectrometer. One of these is the magnetic pulse method, which employs the existing air coil system to reduce the magnetic guiding field in the spectrometer on a short timescale in order to remove low- and high-energy stored electrons. Here we describe the working principle of this method and present results from commissioning measurements at the main spectrometer. Simulations with the particle-tracking software Kassiopeia were carried out to gain a detailed understanding of the electron storage conditions and removal processes
New Constraint on the Local Relic Neutrino Background Overdensity with the First KATRIN Data Runs
We report on the direct search for cosmic relic neutrinos using data acquired during the first two science campaigns of the KATRIN experiment in 2019. Beta-decay electrons from a high-purity molecular tritium gas source are analyzed by a high-resolution MAC-E filter around the end point at 18.57 keV. The analysis is sensitive to a local relic neutrino overdensity ratio of η < 9.7 Ă 10/α (1.1 Ă 10/α) at a 90% (95%) confidence level with α = 1 (0.5) for Majorana (Dirac) neutrinos. A fit of the integrated electron spectrum over a narrow interval around the end point accounting for relic neutrino captures in the tritium source reveals no significant overdensity. This work improves the results obtained by the previous neutrino mass experiments at Los Alamos and Troitsk. We furthermore update the projected final sensitivity of the KATRIN experiment to η < 1Ă10/α at 90% confidence level, by relying on updated operational conditions
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
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