Tritium–helium-3 mass difference using the Penning trap mass spectroscopy

The atomic masses of both ³H and ³He have been measured with a Penning trap mass spectrometer that utilizes a frequency-shift detector to observe ion cyclotron resonances. Present resolution exceeds 1 part in 10⁹ and is limited only by the stability of the magnetic field. The leading systematic shift (at {}1 part in 10¹⁰) is due to the residual quadratic B field dependence. The atomic masses have been combined to yield {Δ}Mc²{(}³H{{{-}}}³$He)=18 590.1(1.7) eV. The excellent agreement with recent results from {β} spectrometers lends strong support for new limits on the neutrino's rest mass.