The KArlsruhe TRItium Neutrino experiment (KATRIN) aims to measure the effective electron anti-neutrino mass with an unprecedented sensitivity of 0.2eV/c2, using β-electrons from tritium decay. The ...electrons are guided magnetically by a system of superconducting magnets through a vacuum beamline from the windowless gaseous tritium source through differential and cryogenic pumping sections to a high resolution spectrometer and a segmented silicon pin detector. At the same time tritium gas has to be prevented from entering the spectrometer. Therefore, the pumping sections have to reduce the tritium flow by more than 14 orders of magnitude. This paper describes the measurement of the reduction factor of the differential pumping section performed with high purity tritium gas during the first measurement campaigns of the KATRIN experiment. The reduction factor results are compared with previously performed simulations, as well as the stringent requirements of the KATRIN experiment.
•Measurement of tritium gas flow reduction in differential pumping in KATRIN.•Reduction of gas flow by more than 7 orders of magnitude.•Excellent agreement between measurement and simulations.•Regeneration interval of KATRIN cryogenic pump longer than 60 days possible.
The KArlsruhe TRItium Neutrino experiment (KATRIN) aims to measure the effective electron anti-neutrino mass with an unprecedented sensitivity of 0.2 eV/c2, using β-electrons from tritium decay. ...Superconducting magnets will guide the electrons through a vacuum beamline from the windowless gaseous tritium source through differential and cryogenic pumping sections to a high resolution spectrometer. At the same time tritium gas has to be prevented from entering the spectrometer. Therefore, the pumping sections have to reduce the tritium flow by at least 14 orders of magnitude. This paper describes various simulation methods in the molecular flow regime used to determine the expected gas flow reduction in the pumping sections for deuterium (commissioning runs) and for radioactive tritium. Simulations with MolFlow+ and with an analytical model are compared with each other, and with the stringent requirements of the KATRIN experiment.
•Simulation of the gas flow of D2 and T2 in differential and the cryogenic pumping in the KATRIN experiment.•The total gas flow is reduced by more than 14 orders of magnitude with the combined pumping systems.•Tritium migration along the beam line due to the sojourn time on Ar-frost and β-induced desorption are investigated.•Two simulation methods are compared; TPMC simulation with MolFlow+, and a custom-made C++ code.
Abstract The neutrino mass experiment KATRIN requires a stability of 3 ppm for the retarding potential at − 18.6 kV of the main spectrometer. To monitor the stability, two custom-made ultra-precise ...high-voltage dividers were developed and built in cooperation with the German national metrology institute Physikalisch-Technische Bundesanstalt (PTB). Until now, regular absolute calibration of the voltage dividers required bringing the equipment to the specialised metrology laboratory. Here we present a new method based on measuring the energy difference of two $$^{83{\mathrm{m}}}$$ 83m Kr conversion electron lines with the KATRIN setup, which was demonstrated during KATRIN’s commissioning measurements in July 2017. The measured scale factor $$M=1972.449(10)$$ M=1972.449(10) of the high-voltage divider K35 is in agreement with the last PTB calibration 4 years ago. This result demonstrates the utility of the calibration method, as well as the long-term stability of the voltage divider.
The neutrino mass experiment KATRIN requires a stability of 3 ppm for the retarding potential at − 18.6 kV of the main spectrometer. To monitor the stability, two custom-made ultra-precise ...high-voltage dividers were developed and built in cooperation with the German national metrology institute Physikalisch-Technische Bundesanstalt (PTB). Until now, regular absolute calibration of the voltage dividers required bringing the equipment to the specialised metrology laboratory. Here we present a new method based on measuring the energy difference of two 83mKr conversion electron lines with the KATRIN setup, which was demonstrated during KATRIN’s commissioning measurements in July 2017. The measured scale factor M=1972.449(10) of the high-voltage divider K35 is in agreement with the last PTB calibration 4 years ago. This result demonstrates the utility of the calibration method, as well as the long-term stability of the voltage divider.
The KArlsruhe TRItium Neutrino experiment (KATRIN) aims to measure the
effective electron anti-neutrino mass with an unprecedented sensitivity of 0.2
eV/c$^2$, using beta-electrons from tritium ...decay. Super-conducting magnets
will guide the electrons through a vacuum beam-line from the windowless gaseous
tritium source through differential and cryogenic pumping sections to a high
resolution spectrometer. At the same time tritium gas has to be prevented from
entering the spectrometer. Therefore, the pumping sections have to reduce the
tritium flow by at least 14 orders of magnitude. This paper describes various
simulation methods in the molecular flow regime used to determine the expected
gas flow reduction in the pumping sections for deuterium (commissioning runs)
and for radioactive tritium. Simulations with MolFlow+ and with an analytical
model are compared with each other, and with the stringent requirements of the
KATRIN experiment.
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.
The KATRIN experiment aims to measure the effective electron antineutrino mass \(m_{\overline{\nu}_e}\) with a sensitivity of 0.2 eV/c\(^2\) using a gaseous tritium source combined with the MAC-E ...filter technique. A low background rate is crucial to achieving the proposed sensitivity, and dedicated measurements have been performed to study possible sources of background electrons. In this work, we test the hypothesis that gamma radiation from external radioactive sources significantly increases the rate of background events created in the main spectrometer (MS) and observed in the focal-plane detector. Using detailed simulations of the gamma flux in the experimental hall, combined with a series of experimental tests that artificially increased or decreased the local gamma flux to the MS, we set an upper limit of 0.006 count/s (90% C.L.) from this mechanism. Our results indicate the effectiveness of the electrostatic and magnetic shielding used to block secondary electrons emitted from the inner surface of the MS.
In this work, we present the first spectroscopic measurements of conversion
electrons originating from the decay of metastable gaseous $^\mathrm{83m}$Kr
with the Karlsruhe Tritium Neutrino (KATRIN) ...experiment. The results obtained
in this calibration measurement represent a major commissioning milestone for
the upcoming direct neutrino mass measurement with KATRIN. The successful
campaign demonstrates the functionalities of the full KATRIN beamline. The
KATRIN main spectrometer's excellent energy resolution of ~ 1 eV made it
possible to determine the narrow K-32 and L$_3$-32 conversion electron line
widths with an unprecedented precision of ~ 1 %.
The KArlsruhe TRItium Neutrino (KATRIN) experiment aims to make a model-independent determination of the effective electron antineutrino mass with a sensitivity of 0.2 eV/c\(^{2}\). It investigates ...the kinematics of \(\beta\)-particles from tritium \(\beta\)-decay close to the endpoint of the energy spectrum. Because the KATRIN main spectrometer (MS) is located above ground, muon-induced backgrounds are of particular concern. Coincidence measurements with the MS and a scintillator-based muon detector system confirmed the model of secondary electron production by cosmic-ray muons inside the MS. Correlation measurements with the same setup showed that about \(12\%\) of secondary electrons emitted from the inner surface are induced by cosmic-ray muons, with approximately one secondary electron produced for every 17 muon crossings. However, the magnetic and electrostatic shielding of the MS is able to efficiently suppress these electrons, and we find that muons are responsible for less than \(17\%\) (\(90\%\) confidence level) of the overall MS background.
The KArlsruhe TRItium Neutrino experiment (KATRIN) aims to measure the effective electron anti-neutrino mass with an unprecedented sensitivity of 0.2 eV/c\(^2\), using beta-electrons from tritium ...decay. Super-conducting magnets will guide the electrons through a vacuum beam-line from the windowless gaseous tritium source through differential and cryogenic pumping sections to a high resolution spectrometer. At the same time tritium gas has to be prevented from entering the spectrometer. Therefore, the pumping sections have to reduce the tritium flow by at least 14 orders of magnitude. This paper describes various simulation methods in the molecular flow regime used to determine the expected gas flow reduction in the pumping sections for deuterium (commissioning runs) and for radioactive tritium. Simulations with MolFlow+ and with an analytical model are compared with each other, and with the stringent requirements of the KATRIN experiment.
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