NEXTEX- The next generation of electron anti-neutrino mass experiment

The design and progress towards meeting the objectives of the Neutrino Mass Experiment in Texas (NEXTEX) is presented. The mass of the electron antineutrino will be inferred from the beta endpoint energy spectrum from gaseous tritium molecules with precision of at least 0.5 eV. Two differential electrostatic spectrometers will be used to analyze the beta electrons near the endpoint energy with 1 eV resolution. The mass of the neutrino will be deduced following the deconvolution of the well established Fermi function and the measured spectrometer function. The correlations between electrodes' potentials and the energy of the transmitted electrons will be determined with high energy electron diffraction on the T$_{2}$ gas. The differential cross section exhibits an oscillatory pattern due to the coherent scattering from the two atoms forming T$_{2}$. This procedure will provide a series of calibration markers for the spectrum with uncertainties of about 100~meV. The background of less than one count a day, at the detector have been demonstrated. The isotopic purity of tritium is monitored by a novel, laser diode based Raman Spectrometer.