Shielded helion magnetic moment to nuclear magneton ratio

$μₕ′/μ_N$ = −2.127 497 7624(17)

Value: −2.127 497 7624
Standard uncertainty: 1.7 × 10⁻⁹
Relative uncertainty: 8.0 × 10⁻¹⁰ (799 parts per trillion)
Status: Measured
Symbol: $μₕ′/μ_N$
Source: CODATA 2022 via NIST · NIST entry

Use in a calculation

# shielded helion magnetic moment to nuclear magneton ratio, CODATA 2022 (NIST)
shielded_helion_magnetic_moment_to_nucle = -2.1274977624  # standard uncertainty 1.7e-9

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

What it is

The magnetic moment of a helion in a helium-3 gas atom (spherical sample at 25 °C), screened by the atom's two electrons, expressed in nuclear magnetons.

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	−2.127 497 7624(17)	8.0 × 10⁻¹⁰	−1.7 σ of 2018
2018	−2.127 497 719(25)	1.2 × 10⁻⁸	+0.0 σ of 2014
2014	−2.127 497 720(25)	1.2 × 10⁻⁸	−0.1 σ of 2010
2010	−2.127 497 718(25)	1.2 × 10⁻⁸	+0.0 σ of 2006
2006	−2.127 497 718(25)	1.2 × 10⁻⁸	+0.2 σ of 2002
2002	−2.127 497 723(25)	1.2 × 10⁻⁸	−0.2 σ of 1998
1998	−2.127 497 718(25)	1.2 × 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).