Kinematic Mass Measurements II: Onward to the "final state"

We consider the sensitivity of future kinematic mass measurements using tritium and Ho-163. Knowledge of the final-state spectra is essential for a correct interpretation of measured spectra in terms of a possible neutrino mass. Important aspects had been overlooked in the case of Ho, and theoretical attention has now been directed to those issues, but the recent new Q-value determination makes this isotope unattractive statistically even if the systematic concerns can be dealt with. The situation in tritium looks better. There is good knowledge of the final state distribution, and Project 8 may offer a path to an atomic tritium experiment.