Shielded helion gyromagnetic ratio in MHz/T

$γₕ′/2π$ = 32.434 100 033(28) MHz T⁻¹

Value: 32.434 100 033 MHz T⁻¹
Standard uncertainty: 2.8 × 10⁻⁸ MHz T⁻¹
Relative uncertainty: 8.6 × 10⁻¹⁰ (863 parts per trillion)
Status: Measured
Symbol: $γₕ′/2π$
Source: CODATA 2022 via NIST · NIST entry

Use in a calculation

# shielded helion gyromagnetic ratio in MHz/T, CODATA 2022 (NIST)
shielded_helion_gyromagnetic_ratio_in_mh = 3.2434100033e1  # MHz T^-1, standard uncertainty 2.8e-8

# SciPy: scipy.constants.physical_constants['shielded helion gyromag. ratio in MHz/T']

What it is

The precession frequency, per tesla of magnetic field, of a helion in a helium-3 gas atom (spherical sample at 25 °C), screened by the atom's two electrons: the gyromagnetic ratio divided by 2π. Magnetic resonance spectroscopists use this form.

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	32.434 100 033(28)	8.6 × 10⁻¹⁰	+1.6 σ of 2018
2018	32.434 099 42(38)	1.2 × 10⁻⁸	−0.6 σ of 2014
2014	32.434 099 66(43)	1.3 × 10⁻⁸	−1.5 σ of 2010
2010	32.434 100 84(81)	2.5 × 10⁻⁸	−1.3 σ of 2006
2006	32.434 101 98(90)	2.8 × 10⁻⁸	+0.2 σ of 2002
2002	32.434 1015(28)	8.6 × 10⁻⁸	−0.7 σ of 1998
1998	32.434 1025(14)	4.3 × 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).