| Atomic Mass | Mass Excess |
| 255.089955504223 amu | 83.793 MeV |
| Level energy (MeV) | Spin & parity | Half-life | Mode of decay | Branch ratio (%) | Decay energy (MeV) |
| Ground state | 7/2+ | 20.07 H 0.07 | A | 100 | 7.24 |
| Ground state | 7/2+ | 20.07 H 0.07 | SF | .00002 | 4 0.000 |
| Decay mode | Half-life | Gamma-ray energy (keV) | Intensity (%) |
| A | 20.07 H 0.07 | .57 | 17.0+- 2.0 |
| A | 20.07 H 0.07 | 58.477 | 0.72+- 0.11 |
| A | 20.07 H 0.07 | 81.477 | 0.81+- 0.09 |