An experiment has been performed to determine the electron neutrino mass with the precision of a few eV by measuring the tritium beta decay energy distribution near the endpoint. Key features of the experiment are a 2 eV resolution electrostatic spectrometer and a high-activity frozen tritium source. It is important that the source have electronic wavefunctions which can be accurately calculated. These calculations have been made for tritium and the HeT/sup +/ daughter ion and allow determination of branching fractions to 0.1% and energy of the excited states to 0.1 eV. The excited final molecular state calculations and the experimental apparatus are discussed. 4 refs., 5 figs.

Pressure vs composition (P-C) isotherms for the UH system for temperatuers of 700 to 1065/sup 0/C and pressures to 137.89 MPa are shown. The sample was contained in a vessel concentric and located within a secondary vessel. Plateau pressure at 1065/sup 0/C is 700 atm. The single-phase region on the hydrogen-rich side starts at a H/U ratio of 2.35. Physical property measurements showed a thermal conductivity, k, value of 0.003 cal/cm sec K, R/sub c/ = 50. Experimentally determined plateau pressures are compared with values obtained by other workers. The UH system retains broad, two-phase plateaus at temperatures to 1065/sup 0/C. The critical temperature must be above 1065/sup 0/C. 13 refs., 3 figs., 1 tab.