Helion mass
Atomic & nuclearMeasured
= 5.006 412 7862(16) × 10−27 kg
- Value
- 5.006 412 7862 × 10−27 kg
- Standard uncertainty
- 1.6 × 10−36 kg
- Relative uncertainty
- 3.2 × 10−10 (320 parts per trillion)
- Status
- Measured
- Symbol
- Source
- CODATA 2022 via NIST · NIST entry
Use in a calculation
# helion mass, CODATA 2022 (NIST)
helion_mass = 5.0064127862e-27 # kg, standard uncertainty 1.6e-36
# SciPy: scipy.constants.physical_constants['helion mass']What it is
The rest mass of the helion, the nucleus of helium-3 (two protons and one neutron), in kilograms.
In other units
| Unit | Value | |
|---|---|---|
| CGS (g) | 5.006 412 7862 × 10−24 | |
| u dalton / atomic mass unit | 3.014 932 247 | unit is itself measured |
| MeV/c² MeV / c² | 2808.391 6111 | |
| GeV/c² GeV / c² | 2.808 391 6111 |
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 | 5.006 412 7862(16) × 10−27 | 3.2 × 10−10 | +4.4 σ of 2018 |
| 2018 | 5.006 412 7796(15) × 10−27 | 3.0 × 10−10 | +1.3 σ of 2014 |
| 2014 | 5.006 412 700(62) × 10−27 | 1.2 × 10−8 | +1.6 σ of 2010 |
| 2010 | 5.006 412 34(22) × 10−27 | 4.4 × 10−8 | +1.7 σ of 2006 |
| 2006 | 5.006 411 92(25) × 10−27 | 5.0 × 10−8 | −0.3 σ of 2002 |
| 2002 | 5.006 412 14(86) × 10−27 | 1.7 × 10−7 | +1.0 σ of 1998 |
| 1998 | 5.006 411 74(39) × 10−27 | 7.8 × 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).