Deuteron-proton magnetic moment ratio

$μ_d/μₚ$ = 0.307 012 209 30(79)

Value: 0.307 012 209 30
Standard uncertainty: 7.9 × 10⁻¹⁰
Relative uncertainty: 2.6 × 10⁻⁹ (2.6 parts per billion)
Status: Measured
Symbol: $μ_d/μₚ$
Source: CODATA 2022 via NIST · NIST entry

Use in a calculation

# deuteron-proton magnetic moment ratio, CODATA 2022 (NIST)
deuteron_proton_magnetic_moment_ratio = 3.070122093e-1  # standard uncertainty 7.9e-10

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

What it is

The magnetic moment of the deuteron divided by the magnetic moment of the proton. 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	0.307 012 209 30(79)	2.6 × 10⁻⁹	−0.1 σ of 2018
2018	0.307 012 209 39(79)	2.6 × 10⁻⁹	+1.1 σ of 2014
2014	0.307 012 2077(15)	4.9 × 10⁻⁹	+0.3 σ of 2010
2010	0.307 012 2070(24)	7.8 × 10⁻⁹	+0.0 σ of 2006
2006	0.307 012 2070(24)	7.8 × 10⁻⁹	−0.3 σ of 2002
2002	0.307 012 2084(45)	1.5 × 10⁻⁸	+0.0 σ of 1998
1998	0.307 012 2083(45)	1.5 × 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).