Helion mass in u
Atomic & nuclearMeasured
= 3.014 932 246 932(74) u
- Value
- 3.014 932 246 932 u
- Standard uncertainty
- 7.4 × 10−11 u
- Relative uncertainty
- 2.5 × 10−11 (25 parts per trillion)
- Status
- Measured
- Symbol
- Source
- CODATA 2022 via NIST · NIST entry
Use in a calculation
# helion mass in u, CODATA 2022 (NIST)
helion_mass_in_u = 3.014932246932 # u, standard uncertainty 7.4e-11
# SciPy: scipy.constants.physical_constants['helion mass in u']What it is
The rest mass of the helion, the nucleus of helium-3 (two protons and one neutron), in unified atomic mass units (daltons), where 1 u is one twelfth of the mass of a carbon-12 atom.
In other units
| Unit | Value | |
|---|---|---|
| CGS (g) | 5.006 412 786 18 × 10−24 | |
| MeV/c² MeV / c² | 2808.391 611 13 | |
| GeV/c² GeV / c² | 2.808 391 611 13 |
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 | 3.014 932 246 932(74) | 2.5 × 10−11 | −2.5 σ of 2018 |
| 2018 | 3.014 932 247 175(97) | 3.2 × 10−11 | +3.7 σ of 2014 |
| 2014 | 3.014 932 246 73(12) | 4.0 × 10−11 | −0.0 σ of 2010 |
| 2010 | 3.014 932 2468(25) | 8.3 × 10−10 | −0.2 σ of 2006 |
| 2006 | 3.014 932 2473(26) | 8.6 × 10−10 | +0.7 σ of 2002 |
| 2002 | 3.014 932 2434(58) | 1.9 × 10−9 | +10.1 σ of 1998 |
| 1998 | 3.014 932 234 69(86) | 2.9 × 10−10 |
“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).