A=9B (1974AJ01)

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⁹B (1974AJ01)

(See Energy Level Diagrams for ⁹B)

GENERAL: See also (1966LA04) and Table 9.9 [Table of Energy Levels] (in PDF or PS).

Model calculations: (1966BA26, 1966EL08, 1967ST1C, 1971CO28, 1972LE1L, 1973HA49).

Special levels: (1966BA26, 1966EL08, 1967BA59, 1967ST1C, 1969HA1G, 1970TO1E, 1971CO28, 1971LI30, 1972BE1E).

Astrophysical questions: (1970BA1M).

Other topics: (1967CA17, 1967CH1H, 1970SA05, 1972AN05, 1972HA57, 1972CA37, 1972LE1L, 1972PN1A, 1973JU2A).

Ground state properties: (1966BA26, 1966EL08, 1968PE16, 1969HE1N, 1969JA1M, 1969LE1D, 1971AU1G, 1972LE1L).

1. (a) ⁶Li(³He, n)⁸B Q_m = -1.975 E_b = 16.604
(b) ⁶Li(³He, p)⁸Be Q_m = 16.788
(c) ⁶Li(³He, d)⁷Be Q_m = 0.1126
(d) ⁶Li(³He, t)⁶Be Q_m = -4.306
(e) ⁶Li(³He, ³He)⁶Li

The total cross section for reaction (a) has been measured from threshold to E(³He) = 3.5 MeV: it increases monotonically reaching the value 4.3 mb at 3.5 MeV (1973MCZW). No structure is observed in the n₀ excitation curve for E(³He) = 4.0 to 5.7 MeV (1967VA24). The yield of ⁸B has also been measured for E(³He) = 8.9 to 26.5 MeV (1973MA24). See also (1966FA1A) and 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)). Resonances are reported at E(³He) = 1.6 MeV (Γ = 0.25 MeV) [1.68 MeV: (1969VI05). J^π = 3/2^- or 5/2^-] and 3.0 MeV (Γ = 1.5 MeV) (1956SC01). Above 5 MeV, the p₀ yield at 0° increases monotonically with energy to E(³He) = 17 MeV (1965FL03). Polarization measurements are reported at E(³He) = 1.4 to 2.0 MeV (1966SI1C, 1971SI1J; p₀, p₁). See also (1970GA1G) and ⁸Be.

The yields of 0.43 and 0.48 MeV γ-rays (reaction (c)), measured 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, J^π = 1/2⁺, 3/2⁺; T = 1/2 (1970AL25). See also ⁷Be.

Excitation functions for ground state tritons (reaction (d)) have been measured for E(³He) = 10 to 16 MeV (1969NU1A) and 23.3 to 25.4 MeV (1972GI07). See also ⁶Be. Differential cross sections have been measured at several angles for the ³He groups to ⁶Li*(0, 2.19) (reaction (e)) for E(³He) = 23.3 to 25.4 MeV (1972GI07). See also ⁶Li.

2. ⁶Li(α, n)⁹B Q_m = -3.975

Angular distributions at E_α = 8.0, 10.0, 12.0 and 14.0 MeV all display strong forward peaking (1963ME08). At E_α = 14.4 MeV, neutron groups are observed to ⁹Be*(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 Q_m = 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 Q_m = 9.353
(b) ⁷Li(³He, np)⁸Be Q_m = 9.538

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 [widths in brackets] (1964DI1A, 1965DI03). (1967BA59) report Q = (-5306 ± 5) keV and therefore E_x = 14.659 ± 0.005 MeV (based on Q_m).

⁹B*(14.66) is the first T = 3/2 state in ⁹B (1965DI03). It γ-decays to ⁹B*(0, 2.4, 2.8) with branching ratios which appear to be similar to those for the analog state in ⁹Be: see Table 9.6 (in PDF or PS). Assuming that the Γ_γ for both T = 3/2 states in ⁹Be, ⁹B are the same, the total Γ for ⁹B*(14.66) is then ≈ 80% of that for ⁹Be*(14.40): 260⁺⁹⁰_-120 eV (1971AD01) [corrected for revised value of Γ of ⁹Be*(14.40)]. The ratio Γ_p₀/Γ_γ₀ < 1.5, Γ_p₁/Γ_γ₀ = 13.9 ± 2.1 [Γ_p₀ is the width for decay of ⁹B*(14.66) to the ground state of ⁸Be; Γ_p₁ is that for decay to ⁸Be*(2.9)]. Assuming Γ_γ₀ for ⁹B*(14.66) = 6.9 ± 0.5 eV [the value for the analog state in ⁹Be: see Table 9.6 (in PDF or PS)], Γ_p₀ < 10 eV, Γ_p₁ = 96 ± 20 eV (1972AD04). See also (1971AD1C).

Angular distributions have been reported for E(³He) = 1.56 to 5.27 MeV (1966DI04; n₀) and 3.1 MeV (1970GU08; n₀). (1970GU08) find that a structure in the neutron spectrum which might correspond to ⁹B*(1.5) is really due to sequential decay of ⁹Be*(11.8) to ⁸Be(0). They also report a ⁹B state with E_x = 4.8 ± 0.1 MeV, Γ = 1.0 ± 0.2 MeV. See also (1970LI1Q), (1969BA1Z) and ¹⁰B.

5. ⁷Be(d, p)⁸Be Q_m = 16.676 E_b = 16.491

For E_d = 0.75 to 1.70 MeV, resonances in the yields of protons are observed at E_d = 0.900 ± 0.025 MeV (p₀, p_2.4) and 1.475 ± 0.010 MeV (p_2.4 only) with Γ_cm = 120 ± 40 and 71 ± 8 keV, respectively [⁹B* = 17.19 and 17.64 MeV] (1960KA17). See (1972PA1C) for astrophysical considerations.

6. ⁹Be(p, n)⁹B Q_m = -1.8498

A high resolution experiment at E_p = 20 MeV shows the population of ⁹B*(0, 2.4) and is 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 E_x < 7.1 MeV (1970AN07). (1972AR22) report E_x = 3.09 ± 0.10 MeV. Additional states have been reported by a number of groups: see (1966LA04) for earlier references and (1967SL04, 1970CL01). The width of the ground state is 540 ± 210 eV (1964TE01).

Angular distributions have been measured at E_p = 3.5 to 10.9 MeV (1965WA04), 6.8 MeV (1967DR08), 8 to 14 MeV (1960SA03), 18.5 MeV (1964AN1B) and 30.3 and 49.3 MeV (1970CL01). See also (1967BO1D, 1969JU1A, 1969VE02, 1970WI1B, 1971BE46, 1971CA1F, 1972CA1Q, 1973WA28), (1966LA04) and (1966PA1H, 1968TH1H; theor.).

7. ⁹Be(³He, t)⁹B Q_m = -1.0860

Angular distributions have been reported at E(³He) = 3.0 to 3.8 MeV (1969OR01; t₀), 5.0 to 9.0 MeV (1967EA01; t₀), 5.7 MeV (1959HI69; t₀), 10 MeV (1967CR04; t₀, t_2.4), 20 to 27.8 MeV (1969OP1A, 1970OP1B; t₀, t_2.4) and 25 MeV (1960WE04; t₀, t_2.4). At E(³He) = 39.8 MeV ⁹Be(0) is very stongly excited and ⁹B*(2.4, 14.7) are also observed. There is some indication that other known ⁹B states are also populated (1969BA06). See also ¹²C in (1975AJ02) and (1970CA28).

8. ⁹Be(⁶Li, ⁶He)⁹B Q_m = -4.577

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* → ⁹Be + p Q_m = 16.677
⁹C(β⁺)⁹B* → ⁵Li + α Q_m = 14.80

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 may decay via ⁵Li + α: see (1972ES05).

10. ¹⁰B(γ, n)⁹B Q_m = -8.435

See ¹⁰B.

11. ¹⁰B(p, d)⁹B Q_m = -6.211

At E_p = 33.6 MeV (1968KU04, 1970KU1D) and 155.6 MeV (1969BA05) deuteron groups are observed to ⁹B*(0, 2.4, 7.0, 11.7, 14.7). All have angular distributions characteristic of l_n = 1 and therefore odd parity and J = (3/2, 5/2, 7/2, 9/2): see Table 9.11 (in PDF or PS). There is some evidence also for the population of ⁹B*(2.8, 18.4) (1968KU04, 1969BA05). Angular distributions have also been reported at E_p = 49.5 MeV (1970SQ01; d₀, d_2.4, d_11.7). See also (1968KR02), (1966LA04) and (1969TO1A; theor.).

12. ¹⁰B(d, t)⁹B Q_m = -2.178
Q₀ = -2.189 ± 0.010 (1967SP09).

Angular distributions have been measured at E_d = 11.8 MeV (1966BA21, 1967FI07; t₀, t_2.4) [S for ⁹B*(0, 2.4) = 0.80 and 0.64, respectively], 13.5 MeV (1964FU15; t₀) and 28 MeV [(1968GA13; t₀); (1971IN1C; t₀, t_2.4 (partial)]. See also (1971WA1K, 1972WA1M) and (1966BA1X, 1971BO50; theor.).

13. (a) ¹⁰B(³He, α)⁹B Q_m = 12.143
(b) ¹⁰B(³He, αp)⁸Be Q_m = 12.328

Alpha particle spectra show the excitation of ⁹B*(0, 2.4, 2.8, 11.8): see (1966LA04). Measurements by (1968KR02) determine E_x = 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 E_x ≈ 1.6 MeV, Γ ≈ 0.7 MeV, but it is not conclusive, in agreement with the older work [see (1960SP08, 1962BA1C)]. No evidence is found for any narrow levels in ⁹B with Γ ≤ 100 keV and 4 < E_x < 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, α_2.4, α_11.8). 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_f < 5.1 x 10^-3] [it decays to ⁵Li(0) by α-emission] while the second state, E_x = 2.71 ± 0.03 MeV [Γ = 0.71 ± 0.06 MeV] decays almost 100% by that channel [θ²_d = 0.74] (1966WI08). (1966WA16) find Γ = 1.1 ± 0.2 MeV for ⁹B*(2.8) and suggest J = 1/2 for this state [see, however, (1960SP08)]. No other excited states of ⁹B with 3.5 < E_x < 9.5 MeV decay by proton emission to ⁸Be(0) (1968KR02). See also (1970BE1F, 1971FO1E) and (1968TA1M; theor.). See also ⁸Be, and ¹³N in (1976AJ04).

14. ¹⁰B(¹⁶O, ¹⁷O)⁹B Q_m = -4.293

See (1968OK06).

15. ¹¹B(p, t)⁹B Q_m = -11.409

At E_p = 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, 17.63). New T = 1/2 states are reported at E_x = 15.29 ± 0.04 and 15.58 ± 0.04 MeV (1971HA10). See also (1971KA04; theor.) and reaction 41 in ⁹Be.

16. (a) ¹²C(p, α)⁹B Q_m = -7.551
(b) ¹²C(p, p)⁴He⁴He⁴He Q_m = -7.2748

Angular distributions of ground state α-particles have been measured at E_p = 14.0 to 17.2 MeV (1969KO1D), 19.1 to 44 MeV (1967AC01, 1969GA03, 1970GU06, 1971GU23), 38.5, 41.6 and 44.5 MeV [also partial back-angle measurements at E_p = 30.5, 32.0, 33.0, 34.5 and 39.5 MeV] (1966CR05, 1967CR05, 1968LI1E) and at E_p = 54.1 MeV (1972MA21). Alpha groups are also observed to ⁹B*(2.3, 2.9 ± 0.2, 6.97 ± 0.06): see (1955RE16, 1962MA40, 1964BA29, 1972MA21). See also (1966LA04). The angular distribution to ⁹B*(6.97) is consistent with J^π = 7/2^-; Γ ≈ 2 MeV (1972MA21: E_p = 54.1 MeV). For reaction (b) see (1972MA62) and (1966LA04). See also ¹²C in (1975AJ02) and ¹³N in (1976AJ04).

17. ¹²C(³He, ⁶Li)⁹B Q_m = -11.571

Angular distributions of ⁶Li ions have been obtained at E(³He) = 28 MeV (1971KL1E), 30.0 and 40.7 MeV (1972OH01) and 35.7 MeV (1969ZE1A, 1970FO1D).