Results of the first Cool-down of the KATRIN Cryogenic Pumping Section

The Karlsruhe Tritium Neutrino (KATRIN) experiment uses the kinematics of tritium β -decay to determine the effective neutrino mass with a sensitivity of m_ν = 200^meV/c² (90% C.L.). In order to measure the decay electrons it is important to guide them adiabatically from the source to the spectrometer. In addition the diffusion of tritium into the spectrometers from the source has to be reduced by 14 orders of magnitude as tritium inside the spectrometers would induce additional background. For these two tasks the transport and pumping section were constructed. The last part of this section is the Cryogenic Pumping Section (CPS), which aims to reduce the residual gas flow by more than seven orders of magnitude. For this a cold argon frost surface, with a ≈ 2 m²) area that is maintained at 3 K, will be prepared to adsorb the incoming tritium molecules. Before the whole KATRIN setup will be connected together the performance of CPS will be tested on its own. This poster presents the measurement results of the first cool-down of the CPS. This work was supported by the GRK1694 and the Helmholtz Association. (paper)