| Atomic Mass | Mass Excess |
| 257.099603447564 amu | 92.78 MeV |
| Level energy (MeV) | Spin & parity | Half-life | Mode of decay | Branch ratio (%) | Decay energy (MeV) |
| Ground state | 0.646 S 0.025 | A | <=100.0 | 0 9.060 | |
| Ground state | 0.646 S 0.025 | SF | <=0.03 | 9.06 |
There is no gamma-rays or the intensities are so weak!