Electron-deuteron magnetic moment ratio

$μₑ/μ_d$ = −2143.923 4921(56)

Value: −2143.923 4921
Standard uncertainty: 5.6 × 10⁻⁶
Relative uncertainty: 2.6 × 10⁻⁹ (2.6 parts per billion)
Status: Measured
Symbol: $μₑ/μ_d$
Source: CODATA 2022 via NIST · NIST entry

Use in a calculation

# electron-deuteron magnetic moment ratio, CODATA 2022 (NIST)
electron_deuteron_magnetic_moment_ratio = -2.1439234921e3  # standard uncertainty 5.6e-6

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

What it is

The magnetic moment of the electron divided by the magnetic moment of the deuteron. 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).

Relative uncertainty

CODATA	Value (uncertainty)	Relative uncertainty	Change from previous
2022	−2143.923 4921(56)	2.6 × 10⁻⁹	−0.1 σ of 2018
2018	−2143.923 4915(56)	2.6 × 10⁻⁹	+0.6 σ of 2014
2014	−2143.923 499(12)	5.6 × 10⁻⁹	−0.1 σ of 2010
2010	−2143.923 498(18)	8.4 × 10⁻⁹	+0.0 σ of 2006
2006	−2143.923 498(18)	8.4 × 10⁻⁹	−0.2 σ of 2002
2002	−2143.923 493(23)	1.1 × 10⁻⁸	+0.2 σ of 1998
1998	−2143.923 498(23)	1.1 × 10⁻⁸

“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).