The primary determination of an electron's mass comes from measuring the ratio of the mass to that of a nucleus, so that the result is obtained in u (atomic mass units). The conversion factor to MeV is more uncertain than the mass of the electron in u; indeed, the recent improvements in the mass determination are not evident when the result is given in MeV. In this datablock we give the result in u, and in the following datablock in MeV.

VALUE ($ 10^{-6} $ u) DOCUMENT ID TECN  COMMENT $548.579909065$ $\pm0.000000016$ TIESINGA 2021 RVUE 2018 CODATA value • • We do not use the following data for averages, fits, limits, etc. • • $548.579909070$ $\pm0.000000016$ MOHR 2016 RVUE 2014 CODATA value $548.57990946$ $\pm0.00000022$ MOHR 2012 RVUE 2010 CODATA value $548.57990943$ $\pm0.00000023$ MOHR 2008 RVUE 2006 CODATA value $548.57990945$ $\pm0.00000024$ MOHR 2005 RVUE 2002 CODATA value $548.5799092$ $\pm0.0000004$ 1 BEIER 2002 CNTR Penning trap $548.5799110$ $\pm0.0000012$ MOHR 1999 RVUE 1998 CODATA value $548.5799111$ $\pm0.0000012$ 2 FARNHAM 1995 CNTR Penning trap $548.579903$ $\pm0.000013$ COHEN 1987 RVUE 1986 CODATA value 1  BEIER 2002 compares Larmor frequency of the electron bound in a ${}^{12}\mathrm {C}{}^{5+}$ ion with the cyclotron frequency of a single trapped ${}^{12}\mathrm {C}{}^{5+}$ ion. 2  FARNHAM 1995 compares cyclotron frequency of trapped electrons with that of a single trapped ${}^{12}\mathrm {C}{}^{6+}$ ion.

References:

TIESINGA 2021 RMP 93 025010 CODATA recommended values of the fundamental physical constants: 2018 MOHR 2016 RMP 88 035009 CODATA Recommended Values of the Fundamental Physical Constants: 2014 MOHR 2012 RMP 84 1527 CODATA Recommended Values of the Fundamental Physical Constants: 2010 MOHR 2008 RMP 80 633 CODATA Recomended Values of the Fundamental Physical Constants: 2006 MOHR 2005 RMP 77 1 NIST Constants BEIER 2002 PRL 88 011603 New Determination of the Electron's Mass MOHR 1999 JPCRD 28 1713 CODATA Recommended Values of the Fundamental Physical Constants: 1998; Also RMP 72 351 CODATA Recommended Values of the Fundamental Physical Constants: 1998 FARNHAM 1995 PRL 75 3598 Determination of the Electron's Atomic Mass and the Proton/Electron Mass Ratio via Penning Trap Mass Spectroscopy COHEN 1987 RMP 59 1121 CODATA Fundamental Physical Constants 1986 Adjustments