The β-decay of 3H (Tritium) to 3He is the most promising candidate for the direct mass determination of the neutrino. A mass larger than zero will modify the shape of the energy spectrum of the emitted β-electron near the high-energy endpoint as illustrated in Fig. 2.1.
The 3H-to-3He mass difference yields the maximum kinetic energy E0 of the released
β-decay electron and thus provides information for the analysis of the β-spectrum (see
Figure 2.1). In 2016, KATRIN is expected to start data acquisition on the β-spectrum,
with the aim of an unprecedented sensitivity of m(νe) < 0.2 eV/c2. This will also lead to a
value for E0.
By taking the recoil and excitation of the daughter core into account, E0 can be calculated and compared with the spectrum, which will be a test of systematic errors for KATRIN.
In order to meet also the safety and the precision requirements, great care has been taken in the preparation of the tritium laboratory at MPIK. Foremostly tritium is a radioactive gas and thus its handling requires special care. Together with the authority in Karlsruhe and the radiation safety group at MPIK, a detailed security policy was developed, which was reviewed and approved by the service company DEKRA. The concept (see figure 2.2) consists of a separate ventilation system, an extra encapsulation of the experiment, glove boxes in the experiment area and an alarm system for a possible tritium spill.