A measurement of the beta spectrum of 63Ni using a new type of cryogenic detector

A precision measurement of the beta spectrum of 63Ni has been performed using a new type of cryogenic particle detector. This is the first nuclear physics experiment using this technique, and we discuss the principles of the method, its advantages and its shortcomings. Careful studies of detector stability, calibration, pulse pile-up and systematics have made it possible to collect large numbers of events (∼ 108) over long periods (∼ 28 days). The measurement is consistent with no 17 keV/c2 neutrino admixture, giving a preferred value of (−0.05 ± 0.31)%.