Mass doublet measurements in the rare earths region and mass doublet calibration of the 12C(n,γ)13C gamma-ray energy

A continuation is given of the precision mass measurement program at the University of Minnesota. In recent years a double focusing spectrometer with a 16-inch magnetic radius and 20-inch electrostatic analyser radius was employed to measure absolute isotopic masses and mass differences. Using the error signal technique, precision of 4 to 7 micromass units for absolute masses is possible. In the present work, absolute masses for selected isotopes of erbium, hafnium, and osmium are reported. These results are combined with other selected mass data to perform a least squares mass adjustment for the region 68 less than or equal to Z less than or equal to 76. Neutron and proton separation energies are calculated and plotted. Comparisons are made to other recent works in this region. Also, an independent and highly accurate determination of the carbon (13) single neutron separation (12C(n,γ)13C gamma-ray energy) was made. This was accomplished by measuring the doublets 12C6D6--13C6H6,12C6D6--12C6H6 and 13C6H6--12C6H12. The error limits of the resulting separation energy are +- 0.05 keV. Also, in the process of measuring this energy, the single neutron separation energy for deuterium was determined. The error limits for this reult are +- 0.04 keV