Helion magnetic moment

$μ_{h}$ = −1.074 617 551 98(93) × 10⁻²⁶ J T⁻¹

Value: −1.074 617 551 98 × 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

# helion magnetic moment, CODATA 2022 (NIST)
helion_magnetic_moment = -1.07461755198e-26  # J T^-1, standard uncertainty 9.3e-36

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

What it is

The magnetic moment of the helion, the nucleus of helium-3 (two protons and one neutron): 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	−1.074 617 551 98(93) × 10⁻²⁶	8.7 × 10⁻¹⁰	−1.5 σ of 2018
2018	−1.074 617 532(13) × 10⁻²⁶	1.2 × 10⁻⁸	−0.7 σ of 2014
2014	−1.074 617 522(14) × 10⁻²⁶	1.3 × 10⁻⁸	−1.3 σ of 2010
2010	−1.074 617 486(27) × 10⁻²⁶	2.5 × 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).