A new value for the deuteron binding energy of B(d)=2.388 176 8(24)×${10}^{\mathrm{-}3}$ u is reported based on an absolute wavelength determination of the 2.2-MeV n-p capture γ ray. Derived values of the n-H and n-p mass differences are also given. We also derive $M_n$=1.008 664 919(14) u. We note that the uncertainties in the neutron-mass data are now dominated by uncertainties arising from mass spectroscopy.

• Received 17 January 1986

DOI:https://doi.org/10.1103/PhysRevLett.56.819