| Paper | Title | Page |
|---|---|---|
TUPPB038 |
Stored Electrons in the KATRIN Spectrometers: Origin, Problems and Counter Measures | |
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| The Karlsruhe Tritium Neutrino Experiment (KATRIN) will probe the absolute neutrino mass scale with a sensitivity of 200 meV (90\% C.L.) by precision spectroscopy of tritium beta-decay electrons. KATRIN uses an ultra-luminous windowless gaseous tritium source with an activity of about 10+11 Bq. The decay electrons are adiabatically guided to the spectrometers by a magnetic field, while the Tritium molecules are removed by differential and cryogenic pumping units. The beta-spectrum is analyzed with an electrostatic spectrometer combined with magnetic collimation. To reach the design sensitivity a very low background rate is required. The potentially dominating background sources inside the spectrometers are electrons emitted by the decay of radon and tritium. A single stored electron in the volume of the main spectrometer can produce an enhanced background level for up to several hours. Therefor passive and active countermeasures are carried out. Tritium is pumped by non-evaporable getter pumps which are on the other hand the principle radon source. So these pumps are separated from the spectrometer volume by liquid nitrogen cooled baffles. To remove already stored electrons, a novel method based on stochastic heating by using the technique of electron cyclotron resonance will be applied. These measures will allow the KATRIN experiment attaining its full physics potential. | ||