The KATRIN experiment aims to measure the effective electron antineutrino mass
m
ν
¯
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.
The KATRIN experiment aims to determine the effective electron neutrino mass with a sensitivity of
0.2
eV/c
2
(%90 CL) by precision measurement of the shape of the tritium
β
-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
219
Rn
and
220
Rn
, 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.
Optimization Calculations for the KATRIN Magnet System Gehring, R.; Osipowicz, A.; Weinheimer, C.
IEEE transactions on applied superconductivity,
06/2006, Letnik:
16, Številka:
2
Journal Article, Conference Proceeding
Recenzirano
The Karlsruhe Tritium Neutrino experiment aims to measure the neutrino mass to extreme high precision by measuring the energy spectrum of the electrons of the tritium decay. A highly specialized ...magnet system is needed to transport the electrons from tritium beta decay along a more than 70 meter long path with differential and cryogenic pumping sections, pre- and main spectrometer to the detector plane. Each magnet group does not only provide a guiding field for the electrons but also serves additional purposes. The intermediate sections between magnet groups as well as the magnet design itself needs to be analyzed very carefully in order to work properly in the whole KATRIN experiment. This paper describes optimization calculations performed to achieve this goal
The goal of the KArlsruhe TRItrium Neutrino (KATRIN) experiment is the determination of the effective electron antineutrino mass with a sensitivity of 0.2eV/c2 at 90% C.L.11C.L. - confidence level.. ...This goal can only be achieved with a very low background level in the order of 10mcps22mcps - milli count per second. in the detector region of interest. A possible background source are α-decays on the inner surface of the KATRIN Main Spectrometer. Rydberg atoms, produced in sputtering processes accompanying the α-decays, are not influenced by electric or magnetic fields and freely propagate inside the vacuum of the Main Spectrometer. Here, they can be ionized by thermal radiation and the released electrons directly contribute to the KATRIN background. Two α-sources, 223Ra and 228Th, were installed at the Main Spectrometer with the purpose of temporarily increasing the background in order to study α-decay induced background processes. In this paper, we present a possible background generation mechanism and measurements performed with these two radioactive sources. Our results show a clear correlation between α-activity on the inner spectrometer surface and background from the volume of the spectrometer. Two key characteristics of the Main Spectrometer background – the dependency on the inner electrode offset potential, and the radial distribution – could be reproduced with this artificially induced background. These findings indicate a high contribution of α-decay induced events to the residual KATRIN background.
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