ADOPTED LEVELS for 216Ac
Author: C. Morse | Citation: Nucl. Data Sheets 209, 409 (2026) | Cutoff date: 5-Aug-2025
Full ENSDF file | Adopted Levels (PDF version)
| Q(β-)=-2149 keV 14 | S(n)= 5952 keV 15 | S(p)= 1671 keV 12 | Q(α)= 9241 keV 3 | ||
| Reference: 2021Wa16 |
| References: | |||
| A | 220Pa α decay (0.82 μs) | B | 220Pa α decay (0.31 μs) |
| C | 220Pa α decay (0.23 μs) | D | 220Pa α decay (0.07 μs) |
| E(level) (keV) | XREF | Jπ(level) | T1/2(level) |
| 0 | ABCD | (1-) | 0.374 ms 22 % α = 100 |
| X? | ≈ 300 ns |
Additional Level Data and Comments:
| E(level) | Jπ(level) | T1/2(level) | Comments |
| X | ≈ 300 ns | α single 322-keV γ ray was reported in 2006PoZX, which apparently depopulated a state with T1/2≈300 ns. The authors hypothesized that this γ ray populates a (9-) isomeric state, which is no longer adopted here (see comment at the top of this dataset). As no other evidence for this state has been observed, its existence should be considered very tenuous. E(level): α single 322-keV γ ray was reported in 2006PoZX, which apparently depopulated a state with T1/2≈300 ns. The authors hypothesized that this γ ray populates a (9-) isomeric state, which is no longer adopted here (see comment at the top of this dataset). As no other evidence for this state has been observed, its existence should be considered very tenuous. |
The previous evaluation of 216Ac (2007Wu02) adopted a 48-keV (9-) isomer. However, as discussed in the most recent evaluation of 212Fr (2020Au03), 2004Ku24 found that the decay data can be explained by a single α-decay from the low-spin ground state. Further, the α-decay hindrance factors do not support a high-spin isomer, and the ratio of the α-decay lines does not change with bombarding energy as expected if there are two different states. Therefore, the 48-keV (9-) level has been removed in the present evaluation.
Q-value: S(2n)=14426 16, S(2p)=5470 13, Q(εp)=543 12 (2021Wa16)