Neutron mass energy equivalent in MeV
Atomic & nuclearMeasured
= 939.565 421 94(48) MeV
- Value
- 939.565 421 94 MeV
- Standard uncertainty
- 4.8 × 10−7 MeV
- Relative uncertainty
- 5.1 × 10−10 (511 parts per trillion)
- Status
- Measured
- Symbol
- Source
- CODATA 2022 via NIST · NIST entry
Use in a calculation
# neutron mass energy equivalent in MeV, CODATA 2022 (NIST)
neutron_mass_energy_equivalent_in_mev = 9.3956542194e2 # MeV, standard uncertainty 4.8e-7
# SciPy: scipy.constants.physical_constants['neutron mass energy equivalent in MeV']What it is
The rest energy (mass × c²) of the neutron, the electrically neutral nucleon, in mega-electronvolts, the unit particle physicists use.
In other units
| Unit | Value | |
|---|---|---|
| CGS (cm2 g s−2) | 0.001 505 349 7651 | |
| keV kiloelectronvolt | 939 565.421 94 | |
| GeV gigaelectronvolt | 0.939 565 421 94 | |
| erg erg | 0.001 505 349 7651 |
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 | 939.565 421 94(48) | 5.1 × 10−10 | +2.6 σ of 2018 |
| 2018 | 939.565 420 52(54) | 5.7 × 10−10 | +1.2 σ of 2014 |
| 2014 | 939.565 4133(58) | 6.2 × 10−9 | +1.6 σ of 2010 |
| 2010 | 939.565 379(21) | 2.2 × 10−8 | +1.4 σ of 2006 |
| 2006 | 939.565 346(23) | 2.4 × 10−8 | −0.2 σ of 2002 |
| 2002 | 939.565 360(81) | 8.6 × 10−8 | +0.8 σ of 1998 |
| 1998 | 939.565 330(38) | 4.0 × 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).