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GENERAL: See Table 11.1 [Table of Energy Levels] (in PDF or PS).

Mass of ¹¹Be: The Q-value of the ⁹Be(t, p)¹¹Be reaction is given as Q = -1.164 ± 0.015 MeV by (PU62) (based on ¹²C(t, p)¹⁴C*). This value has been adjusted by (RY65) to -1.170 MeV, leading to M - A for ¹¹Be = 20.181 ± 0.015 MeV (relative to ¹²C) (MA65A).

See (TA60D, TA60L, DO61, RO66S, DE67P). The ground state of ¹¹Be has even parity (AL64I).

1. 11Be(β-)11B

Qm = 11.513

The decay proceeds to the ¹¹B states at 0, 2.12, 6.79 and 8.00 MeV (J^π = 3/2^-, 1/2^-, 3/2⁺, 3/2⁺, respectively); the half-life is 13.68 ± 0.14 sec. The nature of the decay indicates even parity, J^π = 1/2⁺, 3/2⁺ or 5/2⁺ for ¹¹Be_g.s. (DO61, AL64I): see ¹¹B.

2. 9Be(t, p)11Be

Qm = -1.170

Proton groups have been observed corresponding to seven states of ¹¹Be: see Table 11.2 (in PDF or PS) (PU62). Angular distributions measured at E_t = 6, 10 and 14 MeV do not show a clear stripping pattern for the ground-state protons. At E_t = 14 MeV, the distribution of protons corresponding to ¹¹Be*(0.319) exhibits an L = 2 pattern indicating J^π = 1/2^-, 5/2^- or 7/2^- (PU62, HI64B). (TA60D) suggest J^π = 1/2⁺ and 1/2^- for the ground and first excited states, respectively. The dimensionless reduced widths θ²_n for E_x = 1.8, 2.7 and 3.4 MeV indicate l = 0, 1 or 2 decay to ¹⁰Be + n, J^π = 1/2^±, 3/2^± or 5/2⁺ (PU62). See also (HO68A).

3. 9Be(6He, α)11Be

Qm = 6.343

See (ST67J) and ¹⁵C.

4. 11B(n, p)11Be

Qm = -10.731

At E_n = 14.8 MeV, σ(nα)/σ(np) = 10.0 ± 1.5 (NU58).

5. 11B(γ, π+)11Be

Qm = -151.09

See (DY62, NE63C).