KATRIN: An experiment to determine the neutrino mass

Abstract

The KArlsruhe TRItium Neutrino (KATRIN) experiment is a next generation, model independent, large scale experiment to determine the neutrino mass by investigating the kinematics of tritium beta-decay with a sensitivity of 200 meV/c2. The measurement setup consists of a high luminosity windowless gaseous molecular tritium source (WGTS), a differential and cryogenic pumped electron transport and tritium retention section, a tandem spectrometer section (pre-spectrometer and main spectrometer) for energy analysis, followed by a detector system for counting transmitted beta-decay electrons. To achieve the desired sensitivity, the WGTS, in which tritium decays with an activity of about 1011 Bq, needs to be stable on the 0.1 % level in injection pressure and temperature at an absolute value of about 30 K. With the capability to create an axial magnetic field of 3.6 T the WGTS is going to be one of the world's most complex superconducting magnet and cryostat systems. The main spectrometer (length 24 m, diameter 10 m), which works as a retarding electrostatic spectrometer, will have an energy resolution of 0.93 eV at 18.6 keV. For the precise energy analysis at the tritium endpoint, a retarding potential of -18.6 kV is needed with 1 ppm stability. To reach the background level needed to achieve the sensitivity, it will be operated at a pressure of 10-11 mbar. This article will give an overview of the KATRIN experiment and its current status.