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## 9B (1979AJ01)

(See Energy Level Diagrams for 9B)

GENERAL: See also (1974AJ01) and Table 9.9 [Table of Energy Levels] (in PDF or PS).

Model calculations: (1977HO1F, 1977OK01, 1978HO1E).

Special levels: (1974IR04, 1975WI1E, 1976IR1B, 1978HO1E).

Astrophysical questions: (1977SI1D).

Pion reactions: (1974KA07).

Other topics: (1974HA1C, 1974IR04, 1976IR1B).

Ground state properties: (1975BE31, 1977OK01).

 1. (a) 6Li(3He, n)8B Qm = -1.975 Eb = 16.603 (b) 6Li(3He, p)8Be Qm = 16.7878 (c) 6Li(3He, d)7Be Qm = 0.113 (d) 6Li(3He, t)6Be Qm = -4.306 (e) 6Li(3He, 3He)6Li (f) 6Li(3He, p)4He4He Qm = 16.8797

The total cross section for reaction (a) increases monotonically from threshold to ≈ 7 mb at 3.8 MeV. It then decreases monotonically from ≈ 20 mb at E(3He) = 5.5 MeV to 7.6 MeV (1974MCZS, 1975MC02) and the decrease continues in the range E(3He) = 8.9 to 26.5 MeV (1973MA24). See also 8B.

The excitation functions for protons leading to 8Be*(0, 2.9) [p0, p1] have been measured for E(3He) = 0.9 to 17 MeV (reaction (b)): see (1974AJ01). Resonances are reported at E(3He) = 1.6 MeV [Jπ = 3/2- or 5/2- (1969VI05), Γ = 0.25 MeV] and 3.0 MeV (Γ = 1.5 MeV) (1956SC01). Total cross sections have been measured for the p1 and p2 groups for E(3He) = 3 - 6 MeV (1976GO1F). Polarization measurements are reported at E(3He) = 14 MeV (1977AS04, 1977IR01: p0, p1). See also 8Be.

The yields of 0.43 and 0.48 MeV γ-rays (reaction (c)) for E(3He) = 0.5 to 1.3 MeV are reported to show the excitation of 9B*(17.20 ± 0.02) with Γ = 110 ± 30 keV, Jπ = 1/2+, 3/2+; T = 1/2 (1970AL25). See also 7Be and (1976KA1D).

Excitation functions for t0 (reaction (d)) have been measured for E(3He) = 10 to 16 and 23.3 to 25.4 MeV: see (1974AJ01). See also 6Be. For reaction (e) see (1972GI07). See also 6Li. The total cross section for reaction (f) has been measured for E(3He) = 3 to 6 MeV (1976GO1F). The yield of α - α coincidences [to 5Lig.s.] has been measured for E(3He) = 1.4 to 1.8 MeV: a resonance is observed at 1.57 ± 0.02 MeV [9B*(17.63)], Γ = 70 ± 20 keV (1978GU15).

 2. 6Li(α, n)9B Qm = -3.975

Angular distributions at Eα = 8.0, 10.0, 12.0 and 14.0 MeV all display strong forward peaking (1963ME08). At Eα = 14.4 MeV, neutron groups are observed to 9B*(0, 2.4): the upper limit of the cross section to a state at ≈ 1.7 MeV is 100 μb/sr or < 0.1 of the ground state group (1964BA29). See also 10B.

 3. 6Li(6Li, t)9B Qm = 0.809

Angular distributions of the t0 group have been measured for E(6Li) = 4.0 to 5.5 MeV and at 7.35 and 9.0 MeV. No evidence was observed for a group corresponding to 9B*(1.6) (1966KI09).

 4. (a) 7Li(3He, n)9B Qm = 9.352 (b) 7Li(3He, np)8Be Qm = 9.537

For E(3He) to 12.5 MeV this reaction populates 9B*(0, 2.4, 2.8, (7.0)) (1963DU12) and levels at 12.06 ± 0.06 [0.8 ± 0.2], 14.01 ± 0.07 [0.39 ± 0.11], 14.670 ± 0.016 [< 0.045], 16.024 ± 0.025 [0.180 ± 0.016], 17.19 and 17.63 MeV (1965DI03) [widths in brackets].

9B*(14.66) is the first T = 3/2 state in 9B. Its decay properties are displayed in Table 9.6 (in PDF or PS) and compared with those of 9Be*(14.40) (1971AD01, 1972AD04, 1976MC10).

The n0 angular distribution has been measured at E(3He) = 3.1 MeV. A state at Ex = 4.8 ± 0.1 MeV, Γ = 1.0 ± 0.2 MeV is also reported (1970GU08). See also (1976RA1G, 1976SL1A) and 10B.

 5. 7Be(d, p)8Be Qm = 16.675 Eb = 16.490

For Ed = 0.75 to 1.70 MeV, resonances in the yields of protons are observed at Ed = 0.900 ± 0.025 MeV (p0, p1) and 1.475 ± 0.010 MeV (p1 only) with Γc.m. = 120 ± 40 and 71 ± 8 keV, respectively [9B* = 17.19 and 17.64 MeV] (1960KA17).

 6. (a) 9Be(p, n)9B Qm = -1.850 (b) 9Be(p, pn)8Be Qm = -1.6652

At Ep = 20 MeV, 9B*(0, 2.4) are populated. The results are consistent with the excitation of 9B*(2.8) [Γ ≈ 0.3 MeV] and 9B*(7.0) [Γ > 1 MeV]. No other states are excited for Ex < 7.1 MeV (1970AN07). Additional states have been reported by a number of groups: see (1974AJ01) and (1978CH07). The width of the ground state is 540 ± 210 eV (1964TE01).

Angular distributions have been reported at many energies in the range Ep = 3.5 to 49.3 MeV [see (1974AJ01)] and at 22.8 MeV (1975CA18: quasi elastic). See also (1978WA1D). A study of reaction (b) at Ep = 5.5 MeV is said to suggest a (19 ± 5)% decay of 9B*(2.4) to 8Beg.s. (1978CH07): see, however, reaction 13. See also (1974BO1H, 1976ANZQ, 1976CA17, 1977JE01, 1977LO10, 1978BY1B, 1978BY1C, 1978GO1G, 1978LO1C) and reactions 15 and 16 in 10B.

 7. 9Be(3He, t)9B Qm = -1.0860

Angular distributions have been measured in the range E(3He) = 3.0 to 25 MeV [see (1974AJ01)] and at 217 MeV (1976WI05: t0, t1). At E(3He) = 39.8 MeV, 9Bg.s. is strongly populated and 9B*(2.4, 14.7) are also observed. There is some indication that other known 9B states are also populated (1969BA06). See also (1976UE01, 1974LO1B) and 12C in (1975AJ02, 1980AJ01).

 8. 9Be(6Li, 6He)9B Qm = -4.575

At E(6Li) = 30.8 and 31.8 MeV the ground state of 9B is strongly excited. 9B*(2.4) is also observed (1970CH19, 1971CH1B). A partial angular distribution for the ground state transition is reported at the higher energy by (1971CH1B).

 9. 9C(β+)9B → 8Be + p Qm = 16.681 → 5Li + α Qm = 14.81

Several groups of delayed protons are observed indicating the involvement of a number of 9B states: see Table 9.10 (in PDF or PS) (1972ES05). It is not possible to determine ft values since some of the 9B states involved in the 9C decay via 5Li + α: see (1972ES05).

 10. 10B(γ, n)9B Qm = -8.436

See 10B.

 11. 10B(p, d)9B Qm = -6.211

Observed groups are displayed in Table 9.11 (in PDF or PS) (1968KU04, 1969BA05, 1970SQ01). See also (1977GU14; α to 9B*(0, 2.36); Ep = 16.7 and 17.7 MeV).

 12. 10B(d, t)9B Qm = -2.179

Angular distributions have been measured at Ed = 11.8, 13.5 and 28 MeV [see (1974AJ01)], at 13.6 MeV (1973ZA06: t0) and at Ed-bar = 15 MeV (1974LU06: t0, t1). S for 9B*(0, 2.4) are 0.66 and 0.58, respectively (1974LU06). See also (1975ZA06), (1974DA1D; theor.) and 12C in (1975AJ02, 1980AJ01).

 13. (a) 10B(3He, α)9B Qm = 12.142 (b) 10B(3He, αp)8Be Qm = 12.3273

Alpha-particle spectra show the excitation of 9B*(0, 2.4, 2.8, 11.8): see (1966LA04). Measurements by (1968KR02) determine Ex = 2.361 ± 0.005 and 2.788 ± 0.030 MeV, Γ = 81 ± 5 and 548 ± 40 keV, respectively [see Table 9.11 (in PDF or PS) in (1966LA04) for other values]. There is some evidence for a state with Ex ≈ 1.6 MeV, Γ ≈ 0.7 MeV, but it is not conclusive, in agreement with the older work. No evidence is found for any narrow levels in 9B with Γ ≤ 100 keV and 4 < Ex < 7 MeV: the upper limit to the intensity of the corresponding α-group is 1% of the intensity of the group to 9B*(2.4) (1968KR02). Angular distributions have been determined at E(3He) = 5.5 MeV (1966CA02: α0) and 33.7 MeV (1971SQ03: α0, α2.4, α11.8). DWBA does not seem to give a good description of the transition to 9B*(11.8) (1971SQ03).

In reaction (b) study of the decays of 9B*(2.4, 2.8) shows that 9B*(2.4) decays < 0.5% by proton emission to 8Be(0) [θ2 < 5.1 × 10-3] [it decays to 5Li(0) by α-emission] while the second state, Ex = 2.71 ± 0.03 MeV [Γ = 0.71 ± 0.06 MeV] decays almost 100% by that channel [θ2d = 0.74] (1966WI08). No other excited states of 9B with 3.5 < Ex < 9.5 MeV decay by proton emission to 8Be(0) (1968KR02). A number of additional states of 9B are reported by (1974FO08). See also (1974LO1B) and (1974AJ01).

 14. 10B(16O, 17O)9B Qm = -4.292

See (1968OK06).

 15. 11B(p, t)9B Qm = -11.409

At Ep = 45 MeV angular distributions have been obtained for the triton groups to 9B*(0, 2.36, 12.06, 14.01, 14.66, 16.02). In addition the spectra show some indication of the groups corresponding to 9B*(7.0, 17.19, 17.64). T = 1/2 states are reported at Ex = 15.29 ± 0.04 and 15.58 ± 0.04 MeV (1971HA10). The first two T = 3/2 states have been observed at Ex = 14.6550 ± 0.0025 (1974KA15) and 17.076 ± 0.004 MeV [Γ = 22 ± 5 keV] (1974BE66). See also (1975BE56) and reaction 42 in 9Be.

 16. (a) 12C(p, α)9B Qm = -7.552 (b) 12C(p, p)4He4He4He Qm = -7.2748

Angular distributions have been measured for the α0 group at Ep = 14.0 to 54.1 MeV. Alpha groups are also observed to 9B*(2.3, 2.9 ± 0.2, 6.97 ± 0.06): see (1974AJ01). The angular distribution to 9B*(6.97) is consistent with Jπ = 7/2-, Γ ≈ 2 MeV (1972MA21: Ep = 54.1 MeV). Angular distributions involving the α0 and α* groups [to 4He*(20.1), 0+] to 9Bg.s. have been studied at Ep = 45.2 MeV (1978DA1C). For reaction (b) see (1974AJ01). See also 12C in (1975AJ02, 1980AJ01), 13N in (1976AJ04) and (1978HA04; theor.).

 17. 12C(3He, 6Li)9B Qm = -11.572

Angular distributions of 6Li ions have been obtained at E(3He) = 30.0 and 40.7 MeV (1972OH01). See also (1974AJ01).