Hamburg 2016 – scientific programme
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T: Fachverband Teilchenphysik
T 6: Neutrinomasse I
T 6.4: Talk
Monday, February 29, 2016, 11:50–12:05, VMP5 SR 0079
Radon-induced backgrounds in the KATRIN Main Spectrometer — •Fabian Harms for the KATRIN collaboration — Karlsruhe Institute of Technology (KIT), Institute for Experimental Nuclear Physics (IEKP)
The KArlsruhe TRItium Neutrino (KATRIN) experiment aims to determine the effective mass of the electron anti-neutrino with a sensitivity of 200 meV/c2 (90% C.L.) by investigating the kinematics of tritium β-decay. One crucial prerequisite to reach this unsurpassed sensitivity is a background level of ≤0.01 counts per second within the 1240-m3 vessel of the KATRIN Main Spectrometer.
In 2014/15, a dedicated series of commissioning measurements was performed in order to identify and characterize the various background sources in the spectrometer. This talk will focus on background generating processes that do follow the radioactive decays of radon atoms in the vessel volume. Besides a well-understood stored-electron induced background that is caused by the decay of the short-lived isotopes 219Rn and 220Rn, this also includes a newly identified background contribution due to a deposition of the progeny of the long-lived isotope 222Rn on inner surfaces of the spectrometer. The characteristics of both background contributions, possible countermeasures, and the consequences for the absolute background level of KATRIN will be discussed.
This work has been supported by the Helmholtz Association and the German BMBF (05A14VK2).