Paper VT-TuM6
The KATRIN Experiment: Vacuum Performance of the Large Main Spectrometer Vessel

Tuesday, October 21, 2008, 9:40 am, Room 205

The scientific objective of the KArlsruhe TRItium Neutrino experiment (KATRIN) is to measure the electron neutrino mass from the β-decay of tritium with an unprecedented sensitivity of 200 meV/c². The kinetic energy of the decay electrons will be measured by an electrostatic spectrometer. Background considerations require a very good vacuum of 10^-11 mbar or better in the large spectrometer vessel (volume 1240 m³, surface: 690 m²). A combination of NEG pumps (S = 10⁶ l/s) and turbo-molecular pumps will provide the necessary pumping speed. In addition a very clean surface and low outgassing rates are mandatory. This talk reports on the manufacturing, vacuum performance before and after bake-out at 350°C.