Muon mass energy equivalent
Atomic & nuclearMeasured
= 1.692 833 804(38) × 10−11 J
- Value
- 1.692 833 804 × 10−11 J
- Standard uncertainty
- 3.8 × 10−19 J
- Relative uncertainty
- 2.2 × 10−8 (22 parts per billion)
- Status
- Measured
- Symbol
- Source
- CODATA 2022 via NIST · NIST entry
Use in a calculation
# muon mass energy equivalent, CODATA 2022 (NIST)
muon_mass_energy_equivalent = 1.692833804e-11 # J, standard uncertainty 3.8e-19
# SciPy: scipy.constants.physical_constants['muon mass energy equivalent']What it is
The rest energy (mass × c²) of the muon, an unstable heavier cousin of the electron (about 207 times its mass) that lives about 2.2 microseconds, in joules.
In other units
| Unit | Value | |
|---|---|---|
| CGS (cm2 g s−2) | 1.692 833 804 × 10−4 | |
| keV kiloelectronvolt | 105 658.3755 | |
| MeV megaelectronvolt | 105.658 3755 | |
| GeV gigaelectronvolt | 0.105 658 3755 | |
| Eₕ hartree | 3 882 873.682 | unit is itself measured |
| Ry rydberg | 7 765 747.363 | unit is itself measured |
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 | 1.692 833 804(38) × 10−11 | 2.2 × 10−8 | +0.0 σ of 2018 |
| 2018 | 1.692 833 804(38) × 10−11 | 2.2 × 10−8 | +0.7 σ of 2014 |
| 2014 | 1.692 833 774(43) × 10−11 | 2.5 × 10−8 | +1.2 σ of 2010 |
| 2010 | 1.692 833 667(86) × 10−11 | 5.1 × 10−8 | +1.7 σ of 2006 |
| 2006 | 1.692 833 510(95) × 10−11 | 5.6 × 10−8 | −0.3 σ of 2002 |
| 2002 | 1.692 833 60(29) × 10−11 | 1.7 × 10−7 | +2.0 σ of 1998 |
| 1998 | 1.692 833 32(14) × 10−11 | 8.3 × 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).