Current Direct Neutrino Mass Experiments

Figure 3

Expanded 𝛽-spectrum of an allowed or superallowed 𝛽-decay around its endpoint 𝐸₀ for 𝑚(𝜈_𝑒)=0 (red line) and for an arbitrarily chosen neutrino mass of 1 eV (blue line). In the case of tritium (see Section 2.2), the gray-shaded area corresponds to a fraction of 2⋅10⁻¹³ of all tritium 𝛽-decays.