Abstract :
In the new tables, the masses of fundamental nuclides such as H, D, 4He, 14N, 16O and even 20Ne and 40Ar could be given with a precision of a few parts in 1010, due to Penning trap cyclotron frequency measurements. The masses of stable Si atoms, of possible importance for the definition of the kg, the only base unit not yet defined in terms of natural constants, are given with 80 ppb (200 eV) accuracy. A repeated Penning trap result for 28Si with a 100 ppb precision confirms the mass table result. Precision reaction and binding energies had now to be given in terms of the 1990 representation of the eV which is 8.1 ppm larger than the preceding (1972) one. Penning trap technology has also been applied on even short-lived (few s) unstable nuclides, with a precision of about 10 keV. Time of flight measurements on very unstable nuclides gave their masses with about 100 keV accuracy. Similar or better accuracy applied to many masses derived from newly measured reaction energies. Information is given on the way in which the mass values in the table have been derived from many thousands of experimental determinations of masses and nuclear reaction and decay energies
Keywords :
atomic mass; collections of physical data; constants; frequency measurement; isotopes; mass measurement; measurement standards; particle traps; silicon; time of flight mass spectra; units (measurement); weighing; 1993 atomic mass tables; 14N; 16O; 20N; 28Si; 40Ar; 4He; Ar; D; H; He; N; Ne; O; Penning trap cyclotron frequency measurements; Si; Si atoms; binding energies; decay energies; fundamental nuclides; kg; measured reaction energies; nuclear reaction; time of flight measurements; unstable nuclides; Argon; Atomic measurements; Cyclotrons; Electrons; Energy measurement; Frequency measurement; Helium; Mass spectroscopy; Neutrino sources; Nuclear measurements;
