Fig. (27) The shape factor of the β-ray spectrum of ³⁵S measured with a cooled Si(Li) detector [192]. In the energy region of 17 keV below the endpoint of Q_β = 167 keV, the observed spectrum deviates by 8 standard deviations from the expected single component β-spectrum. Solid line includes the 17 keV neutrino mass component with an admixture of 0.0084 ± 0.0006_stat ± 0.0005_syst.