Evaluation Home Page |
| Information on mass chains and nuclides |
|
 |
8B (1966LA04)
(See Energy Level Diagrams for 8B)
GENERAL: See (1958FO1C, 1960TA1C, 1962IN02, 1963NA1E, 1964BA1X, 1964BA2A, 1964GR1J, 1964ST1B).
See also Table 8.18 [Table of Energy Levels] (in PDF or PS).
| 1. 8B(β+)8Be | Qm = 17.979 |
The beta decay leads mainly to 8Be*(2.9). Reported half lives are listed in Table 8.19 (in PDF or PS); taking τ1/2 = 0.774 sec and Q = 17.979 - 2.90, ft = 4.41 × 105 (1966BA1A). There is also observed a branch to a 8Be state at ≈ 16.6 MeV; log ft = 2.9 (1964MA35). See also (1964BA1X) and 8Be.
| 2. 6Li(3He, n)8B | Qm = -1.975 |
Thresholds for production of slow neutrons are reported at E(3He) = 2.9661 ± 0.0017 MeV (1958DU78), 2.974 ± 0.010 MeV (1959FA02), corresponding to the ground state of 8B, and at E(3He) = 4.16 ± 0.05 (1958DU78), 4.159 ± 0.030 MeV (1959FA02), corresponding to an excited state at Ex = 0.789 ± 0.030 MeV with Γc.m. = 70 ± 40 keV. A threshold at 3.9 MeV reported by (1958DU78) is not confirmed by (1959FA02).
Neutron time-of-flight spectra at E(3He) = 4 to 9 MeV show groups corresponding to 8B(0) and 8B*(0.8), with forward-peaked angular distributions, and to a new state at Ex = 2.17 ± 0.05 MeV (1963DI02). At E(3He) = 4.5 to 5.3 MeV, time-of-flight spectra locate the first excited state at 0.767 ± 0.012 (1965FA03), 0.783 ± 0.010 MeV (1965MC06: Γ = 40 ± 10 keV). See also (1963MO1J).
| 3. 7Be(p, γ)8B | Qm = 0.135 |
The cross section for proton capture is 0.48 ± 0.18 μb at Ep = 0.80 MeV and 0.50 ± 0.20 μb at Ep = 1.40 MeV (1960KA05). The relevance of this reaction in stellar energy production is discussed by (1958FO1C, 1960KA05, 1963BA2D, 1964BA2A, 1964PA1A). See also (1961CH1C).
| 4. (a) 10B(p, t)8B | Qm = -18.532 |
| (b) 9Be(p, 2n)8B | Qm = -20.426 |
| (c) 12C(p, nα)8B | Qm = -26.130 |
See (1950AL57).
| 5. (a) 10B(γ, 2n)8B | Qm = -27.014 |
| (b) 11B(γ, 3n)8B | Qm = -38.470 |
| (c) 12C(γ, p3n)8B | Qm = -54.426 |
See (1952SH44).