# ${{\boldsymbol e}}$ MASS (atomic mass units u) INSPIRE search

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
$548.579909070$ $\pm0.000000016$
 2016
RVUE 2014 CODATA value
• • • We do not use the following data for averages, fits, limits, etc. • • •
$548.57990946$ $\pm0.00000022$
 2012
RVUE 2010 CODATA value
$548.57990943$ $\pm0.00000023$
 2008
RVUE 2006 CODATA value
$548.57990945$ $\pm0.00000024$
 2005
RVUE 2002 CODATA value
$548.5799092$ $\pm0.0000004$ 1
 2002
CNTR Penning trap
$548.5799110$ $\pm0.0000012$
 1999
RVUE 1998 CODATA value
$548.5799111$ $\pm0.0000012$ 2
 1995
CNTR Penning trap
$548.579903$ $\pm0.000013$
 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:
 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;
 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