ConstantID

Neutron-electron magnetic moment ratio

Atomic & nuclearMeasured

μn/μe = 1.040 668 84(24) × 10−3

Value
1.040 668 84 × 10−3
Standard uncertainty
2.4 × 10−10
Relative uncertainty
2.3 × 10−7 (231 parts per billion)
Status
Measured
Symbol
μn/μe
Source
CODATA 2022 via NIST · NIST entry

Use in a calculation

# neutron-electron magnetic moment ratio, CODATA 2022 (NIST)
neutron_electron_magnetic_moment_ratio = 1.04066884e-3  # standard uncertainty 2.4e-10

# SciPy: scipy.constants.physical_constants['neutron-electron mag. mom. ratio']

What it is

The magnetic moment of the neutron divided by the magnetic moment of the electron. Ratios like this are often measured more precisely than either quantity on its own, which is why CODATA lists them.

How the value changed, 1998–2022

Each point is one CODATA adjustment, plotted as its difference from the 2022 value; the bars show one standard uncertainty (an arrowhead means the bar runs off the chart).

neutron-electron magnetic moment ratio: CODATA values 1998–2022 relative to the 2022 value, in parts per billion, with one-standard-uncertainty bars−600−400−2000+200+400+600parts per billion1998200220062010201420182022

Relative uncertainty

neutron-electron magnetic moment ratio: relative standard uncertainty in each CODATA adjustment, logarithmic scale10⁻⁸10⁻⁷10⁻⁶1998200220062010201420182022
CODATAValue (uncertainty)Relative uncertaintyChange from previous
20221.040 668 84(24) × 10−32.3 × 10−7 +0.1 σ of 2018
20181.040 668 82(25) × 10−32.4 × 10−7 +0.0 σ of 2014
20141.040 668 82(25) × 10−32.4 × 10−7 +0.0 σ of 2010
20101.040 668 82(25) × 10−32.4 × 10−7 +0.0 σ of 2006
20061.040 668 82(25) × 10−32.4 × 10−7 +0.0 σ of 2002
20021.040 668 82(25) × 10−32.4 × 10−7 +0.0 σ of 1998
19981.040 668 82(25) × 10−32.4 × 10−7

“Change from previous” is the shift in the value divided by the standard uncertainty of the previous adjustment. Earlier values are converted into the current unit where NIST changed it (for example J s to J Hz⁻¹).

Related constants

Atomic & nuclear λC,n Neutron Compton wavelength 1.319 590 903 82(67) × 10−15 m Atomic & nuclear mn/me Neutron-electron mass ratio 1838.683 662 00(74) Atomic & nuclear gn Neutron g factor −3.826 085 52(90) Atomic & nuclear γn Neutron gyromagnetic ratio 1.832 471 74(43) × 108 s−1 T−1 Atomic & nuclear γn/2π Neutron gyromagnetic ratio in MHz/T 29.164 6935(69) MHz T−1 Atomic & nuclear μn Neutron magnetic moment −9.662 3653(23) × 10−27 J T−1 Atomic & nuclear μn/μB Neutron magnetic moment to Bohr magneton ratio −1.041 875 65(25) × 10−3 Atomic & nuclear μn/μN Neutron magnetic moment to nuclear magneton ratio −1.913 042 76(45)