Alpha particle mass energy equivalent in MeV
Atomic & nuclearMeasured
= 3727.379 4118(12) MeV
- Value
- 3727.379 4118 MeV
- Standard uncertainty
- 1.2 × 10−6 MeV
- Relative uncertainty
- 3.2 × 10−10 (322 parts per trillion)
- Status
- Measured
- Symbol
- Source
- CODATA 2022 via NIST · NIST entry
Use in a calculation
# alpha particle mass energy equivalent in MeV, CODATA 2022 (NIST)
alpha_particle_mass_energy_equivalent_in = 3.7273794118e3 # MeV, standard uncertainty 1.2e-6
# SciPy: scipy.constants.physical_constants['alpha particle mass energy equivalent in MeV']What it is
The rest energy (mass × c²) of the alpha particle, the nucleus of helium-4 (two protons and two neutrons), in mega-electronvolts, the unit particle physicists use.
In other units
| Unit | Value | |
|---|---|---|
| CGS (cm2 g s−2) | 0.005 971 920 1996 | |
| keV kiloelectronvolt | 3 727 379.4118 | |
| GeV gigaelectronvolt | 3.727 379 4118 | |
| erg erg | 0.005 971 920 1996 |
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 | 3727.379 4118(12) | 3.2 × 10−10 | +4.7 σ of 2018 |
| 2018 | 3727.379 4066(11) | 3.0 × 10−10 | +1.2 σ of 2014 |
| 2014 | 3727.379 378(23) | 6.2 × 10−9 | +1.7 σ of 2010 |
| 2010 | 3727.379 240(82) | 2.2 × 10−8 | +1.4 σ of 2006 |
| 2006 | 3727.379 109(93) | 2.5 × 10−8 | −0.2 σ of 2002 |
| 2002 | 3727.379 17(32) | 8.6 × 10−8 | +0.9 σ of 1998 |
| 1998 | 3727.379 04(15) | 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).