Deuteron-electron magnetic moment ratio

$μ_d/μₑ$ = −4.664 345 550(12) × 10⁻⁴

Value: −4.664 345 550 × 10⁻⁴
Standard uncertainty: 1.2 × 10⁻¹²
Relative uncertainty: 2.6 × 10⁻⁹ (2.6 parts per billion)
Status: Measured
Symbol: $μ_d/μₑ$
Source: CODATA 2022 via NIST · NIST entry

Use in a calculation

# deuteron-electron magnetic moment ratio, CODATA 2022 (NIST)
deuteron_electron_magnetic_moment_ratio = -4.66434555e-4  # standard uncertainty 1.2e-12

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

What it is

The magnetic moment of the deuteron 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).

Relative uncertainty

CODATA	Value (uncertainty)	Relative uncertainty	Change from previous
2022	−4.664 345 550(12) × 10⁻⁴	2.6 × 10⁻⁹	+0.1 σ of 2018
2018	−4.664 345 551(12) × 10⁻⁴	2.6 × 10⁻⁹	−0.6 σ of 2014
2014	−4.664 345 535(26) × 10⁻⁴	5.6 × 10⁻⁹	+0.1 σ of 2010
2010	−4.664 345 537(39) × 10⁻⁴	8.4 × 10⁻⁹	+0.0 σ of 2006
2006	−4.664 345 537(39) × 10⁻⁴	8.4 × 10⁻⁹	+0.2 σ of 2002
2002	−4.664 345 548(50) × 10⁻⁴	1.1 × 10⁻⁸	−0.2 σ of 1998
1998	−4.664 345 537(50) × 10⁻⁴	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).