Shielded helion to proton magnetic moment ratio

$μₕ′/μₚ$ = −0.761 766 577 21(66)

Value: −0.761 766 577 21
Standard uncertainty: 6.6 × 10⁻¹⁰
Relative uncertainty: 8.7 × 10⁻¹⁰ (866 parts per trillion)
Status: Measured
Symbol: $μₕ′/μₚ$
Source: CODATA 2022 via NIST · NIST entry

Use in a calculation

# shielded helion to proton magnetic moment ratio, CODATA 2022 (NIST)
shielded_helion_to_proton_magnetic_momen = -7.6176657721e-1  # standard uncertainty 6.6e-10

# SciPy: scipy.constants.physical_constants['shielded helion to proton mag. mom. ratio']

What it is

The magnetic moment of the shielded helion 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	−0.761 766 577 21(66)	8.7 × 10⁻¹⁰	−1.7 σ of 2018
2018	−0.761 766 5618(89)	1.2 × 10⁻⁸	−0.2 σ of 2014
2014	−0.761 766 5603(92)	1.2 × 10⁻⁸	−0.2 σ of 2010
2010	−0.761 766 558(11)	1.4 × 10⁻⁸	+0.0 σ of 2006
2006	−0.761 766 558(11)	1.4 × 10⁻⁸	+0.3 σ of 2002
2002	−0.761 766 562(12)	1.6 × 10⁻⁸	+0.1 σ of 1998
1998	−0.761 766 563(12)	1.6 × 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).