Shielded helion magnetic moment

$μ_{h^{'}}$ = −1.074 553 110 35(93) × 10⁻²⁶ J T⁻¹

Value: −1.074 553 110 35 × 10⁻²⁶ J T⁻¹
Standard uncertainty: 9.3 × 10⁻³⁶ J T⁻¹
Relative uncertainty: 8.7 × 10⁻¹⁰ (865 parts per trillion)
Status: Measured
Symbol: $μ_{h^{'}}$
Source: CODATA 2022 via NIST · NIST entry

Use in a calculation

# shielded helion magnetic moment, CODATA 2022 (NIST)
shielded_helion_magnetic_moment = -1.07455311035e-26  # J T^-1, standard uncertainty 9.3e-36

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

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: how strongly it behaves like a tiny bar magnet. A negative value means it points opposite to the spin.

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	−1.074 553 110 35(93) × 10⁻²⁶	8.7 × 10⁻¹⁰	−1.6 σ of 2018
2018	−1.074 553 090(13) × 10⁻²⁶	1.2 × 10⁻⁸	−0.7 σ of 2014
2014	−1.074 553 080(14) × 10⁻²⁶	1.3 × 10⁻⁸	−1.3 σ of 2010
2010	−1.074 553 044(27) × 10⁻²⁶	2.5 × 10⁻⁸	−2.1 σ of 2006
2006	−1.074 552 982(30) × 10⁻²⁶	2.8 × 10⁻⁸	+0.5 σ of 2002
2002	−1.074 553 024(93) × 10⁻²⁶	8.7 × 10⁻⁸	−1.3 σ of 1998
1998	−1.074 552 967(45) × 10⁻²⁶	4.2 × 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).