XXth International Conference on Neutrino Physics and Astrophysics
Novel Search for Heavy Neutrino Mixing from the Positron Decay of
K-38m Confined in an Atom Trap
A new technique, neutrino momentum spectroscopy, is used to set limits
on the admixture of heavy neutrinos into the electron neutrino. We
measure coincidences between nuclear recoils and positrons from the
beta decay of trapped radioactive atoms and deduce the neutrino
momentum. A two-dimensional maximum likelihood search for peaks in the
resulting reconstructed recoil time-of-flight spectrum as a function
of positron energy is performed. The admixture upper limits range from
4x10^-3 to 2x10^-2 and are the best direct limits for neutrinos (as
opposed to antineutrinos) for the mass region of 0.7 to 3.5 MeV.
See PDF Version of Poster.