Neutron mass energy equivalent
Atomic & nuclearMeasured
= 1.505 349 765 14(76) × 10−10 J
- Value
- 1.505 349 765 14 × 10−10 J
- Standard uncertainty
- 7.6 × 10−20 J
- Relative uncertainty
- 5.0 × 10−10 (505 parts per trillion)
- Status
- Measured
- Symbol
- Source
- CODATA 2022 via NIST · NIST entry
Use in a calculation
# neutron mass energy equivalent, CODATA 2022 (NIST)
neutron_mass_energy_equivalent = 1.50534976514e-10 # J, standard uncertainty 7.6e-20
# SciPy: scipy.constants.physical_constants['neutron mass energy equivalent']What it is
The rest energy (mass × c²) of the neutron, the electrically neutral nucleon, in joules.
In other units
| Unit | Value | |
|---|---|---|
| CGS (cm2 g s−2) | 0.001 505 349 765 14 | |
| keV kiloelectronvolt | 939 565.421 936 | |
| MeV megaelectronvolt | 939.565 421 936 | |
| GeV gigaelectronvolt | 0.939 565 421 936 | |
| erg erg | 0.001 505 349 765 14 |
Converted with ConstantID's unit table; digits are rounded to the precision of the value, and a long exact value is rounded only for display. The relative uncertainty is unchanged by conversion to an exactly defined unit.
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 | 1.505 349 765 14(76) × 10−10 | 5.0 × 10−10 | +2.6 σ of 2018 |
| 2018 | 1.505 349 762 87(86) × 10−10 | 5.7 × 10−10 | +1.3 σ of 2014 |
| 2014 | 1.505 349 739(19) × 10−10 | 1.3 × 10−8 | +1.6 σ of 2010 |
| 2010 | 1.505 349 631(66) × 10−10 | 4.4 × 10−8 | +1.7 σ of 2006 |
| 2006 | 1.505 349 505(75) × 10−10 | 5.0 × 10−8 | −0.2 σ of 2002 |
| 2002 | 1.505 349 57(26) × 10−10 | 1.7 × 10−7 | +0.9 σ of 1998 |
| 1998 | 1.505 349 46(12) × 10−10 | 8.0 × 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).