Neutron gyromagnetic ratio in MHz/T

$γₙ/2π$ = 29.164 6935(69) MHz T⁻¹

Value: 29.164 6935 MHz T⁻¹
Standard uncertainty: 6.9 × 10⁻⁶ MHz T⁻¹
Relative uncertainty: 2.4 × 10⁻⁷ (237 parts per billion)
Status: Measured
Symbol: $γₙ/2π$
Source: CODATA 2022 via NIST · NIST entry

Use in a calculation

# neutron gyromagnetic ratio in MHz/T, CODATA 2022 (NIST)
neutron_gyromagnetic_ratio_in_mhz_t = 2.91646935e1  # MHz T^-1, standard uncertainty 6.9e-6

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

What it is

The precession frequency, per tesla of magnetic field, of the neutron, the electrically neutral nucleon: 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	29.164 6935(69)	2.4 × 10⁻⁷	+0.1 σ of 2018
2018	29.164 6931(69)	2.4 × 10⁻⁷	−0.0 σ of 2014
2014	29.164 6933(69)	2.4 × 10⁻⁷	−0.1 σ of 2010
2010	29.164 6943(69)	2.4 × 10⁻⁷	−0.2 σ of 2006
2006	29.164 6954(69)	2.4 × 10⁻⁷	+0.1 σ of 2002
2002	29.164 6950(73)	2.5 × 10⁻⁷	−0.1 σ of 1998
1998	29.164 6958(70)	2.4 × 10⁻⁷

“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).