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9B (1959AJ76)
(See the Energy Level Diagram for 9B)
GENERAL: See also Table 9.4 [Table of Energy Levels] (in PDF or PS).
| 1. 6Li(3He, p)8Be | Qm = 16.786 | Eb = 16.598 |
The excitation functions for protons leading to the ground and 2.9-MeV excited states of 8Be have been measured for E(3He) = 0.9 to 5.1 MeV (θ = 0° and 150°, lab.). Resonances are observed at E(3He) = 1.6 MeV (Γ = 0.25 MeV, 9B* = 17.6 MeV) and 3.0 MeV (Γ = 1.5 MeV, 9B* = 18.6 MeV) (1956SC01). However, J.W. Butler (private communication) suggests that the decrease in the yield for E(3He) ≳ 3 MeV can be accounted for by competition from the 6Li(3He, n)8B reaction with a threshold at 2.966 MeV. Angular distributions, taken at 6 energies, are isotropic at ≈ 1 MeV and become increasingly asymmetric at higher energies. In particular, the ground state protons exhibit strong backward peaking for E(3He) ≳ 3 MeV (1956SC01).
| 2. 6Li(α, n)9B | Qm = -3.979 |
See (1956RO06).
| 3. 7Li(3He, n)9B | Qm = 9.346 |
Not reported.
| 4. 9Be(p, n)9B | Qm = -1.854 |
The width of the ground state is < 2 keV (1951ST76). At Ep = 6.59 MeV, a neutron group is observed corresponding to a level at 2.37 ± 0.04 MeV. A continuous distribution of neutrons, attributed to the (p, p'n) reaction, is also observed (1953AJ09, 1959MA20: see also (1950JO1B) and 9Be). For Ep = 2 to 5.8 MeV, two neutron thresholds have been observed at Ep = 2.060 ± 0.003 and 4.645 ± 0.005 MeV (9B* = 2.326 ± 0.006 MeV + 1/2 Γ). The continued slow neutron yield above threshold suggests l = 1 neutron emission (1955MA84). A broad threshold reported at Ep = 3.6 MeV appears to have been due to variation in counter sensitivity. It is possible, however, that part of the continuum neutron spectrum arises from a 9B level expected near 1.4 MeV (1959MA20). See also (1957KI1B, 1958BO63).
| 5. 9Be(3He, t)9B | Qm = -1.089 |
The ground state angular distributions are peaked in the forward direction at E(3He) = 5.7 MeV (S. Hinds and R. Middleton) and 21 MeV (1958WE1E).
| 6. 10B(γ, n)9B | Qm = -8.439 |
See (1951SH63).
| 7. 10B(p, d)9B | Qm = -6.212 |
At Ep = 18.9 MeV, deuteron groups are observed corresponding to the ground state of 9B and to an excited state at 2.40 ± 0.15 MeV. The angular distributions to both states, analyzed by pickup theory, show an l = 1 transfer, indicating odd parity, 1/2 < J ≤ 9/2, for these states (1956RE04). The ratio of cross sections is in good agreement with an intermediate-coupling calculation (1955FR1F).
| 8. 10B(d, t)9B | Qm = -2.180 |
| Q0 = -2.187 ± 0.010 (1956BO18). |
| 9. 10B(3He, α)9B | Qm = 12.139 |
At E(3He) = 1 MeV, alpha-particle groups have been observed corresponding to the ground state of 9B and to an excited state at 2.58 ± 0.13 MeV (1955AL57). At E(3He) = 2 to 3 MeV, groups are observed corresponding to the ground state and to levels at Ex = 2.37 ± 0.02 MeV and 2.83 ± 0.03 MeV. The widths are 80 keV and 300 keV for 9B*(2.37) and 9B*(2.83), respectively. There is no evidence of a well-defined state corresponding to 9Be*(1.75) (1958PO61, 1959PO61). See also (1959SP17).
| 10. 11B(p, t)9B | Qm = -11.418 |
Not observed.
| 11. 12C(p, α)9B | Qm = -7.563 |
| Q0 = -7.58 ± 0.1 (1955RE16). |
At Ep = 18.8 MeV, alpha-particle groups have been observed to the ground state of 9B and to an excited state at 2.39 ± 0.08 MeV. The two α-groups are superimposed on a background possibly due to 12C(p, p')12C* →3α. The average differential cross section for the ground state group at Ep ≈ 18 MeV is 3 ± 1 mb/sr. No other groups were observed up to Ex ≈ 7.9 MeV (1955RE16). The angular distribution of the ground state group at Ep = 15.6 to 18.6 MeV is consistent with triton pickup or knock-on theories, except for discrepancies at low angles (1958MA40). At Ep = 29 MeV, the reaction appears to go to the ground state and to a level at 3.2 ± 1.0 MeV (1955NE18: stars in a cloud chamber; 12C + p →α + 9B →3α + p). At Ep = 32 MeV, groups corresponding to 9B(0), 9B*(2.4) and a new level at 7.0 MeV are observed (1958KN52).