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USNDP

11B (1980AJ01)


(See Energy Level Diagrams for 11B)

GENERAL: See also (1975AJ02) and Table 11.3 [Table of Energy Levels] (in PDF or PS).

Shell model: (1977BO07, 1977JA14, 1977TE01, 1978BO31).

Cluster, collective and rotational models: (1976BR26, 1977BO07, 1977NI1A, 1977OK1C, 1979NI06).

Special levels: (1976IR1B, 1977BO07, 1977JA14, 1977TE01, 1977TE02, 1978BO31, 1979NI06).

Electromagnetic transitions: (1974HA1C, 1977BO07, 1977DO06, 1977OK1C, 1977TE01, 1977TE02, 1978KI08, 1979NI06).

Astrophysical questions: (1975AR1E, 1975HA1N, 1975ME1E, 1975PR1B, 1975TR1A, 1976AU1B, 1976AU1C, 1976BO1E, 1976CO1B, 1976EP1A, 1976GI1C, 1976HA1F, 1976RO1J, 1976SI1C, 1976VI1A, 1977AU1B, 1977DW1A, 1977HA1L, 1977KO1L, 1977MA1H, 1977SC1D, 1978AU1C, 1978BO1K, 1978BU1B, 1978BY1A, 1978DI04, 1978DI1D, 1978DW1A, 1978DW1B, 1978ME1D, 1979MC1A).

Special reactions: (1975AB1D, 1975AR14, 1975HU14, 1975RA21, 1976BE1K, 1976BU16, 1976HE1H, 1976LE1F, 1976NA11, 1976OS04, 1976RA1C, 1976RO12, 1976YOZZ, 1977AR06, 1977FO04, 1977GE08, 1977GO07, 1977KU1D, 1977RE08, 1977SH1D, 1977ST1G, 1977UD1A, 1977YA1B, 1978BH03, 1978BI08, 1978GE1C, 1978GR1F, 1978HE1C, 1978KO01, 1978LE15, 1978PE1E, 1978TU06, 1978VO1D, 1978WE1D, 1978ZE02, 1979CR03, 1979DY01, 1979GA04, 1979GO11, 1979PA09, 1979SC08, 1979VI05, 1979WE06).

Muon and neutrino capture and reactions: (1974EN10, 1974WA1C, 1975DO1F, 1975DO1D, 1976DO1G, 1977CA1E, 1977DO06, 1977MU1A, 1977WA1G, 1978DE15, 1978LE04, 1979BE1N, 1979DE01).

Pion capture and reactions (See also reactions 27, 38 and 54.): (1975HU1D, 1975ZI1B, 1976BAYR, 1976CA1H, 1976KA1F, 1976MI15, 1976NO1D, 1977BA2H, 1977BA1Q, 1977BA2G, 1977BE1L, 1977DO06, 1977HO1B, 1977KO25, 1977MA35, 1977PI1D, 1977SI01, 1978CO02, 1978KI08, 1978KI13, 1978MO01, 1978SI1D, 1978TS1A, 1979BE1N, 1979BO1U, 1979EL1E, 1979HU02, 1979TI1A, 1979ZI1C).

Reactions and kaons and other mesons: (1975TA1C, 1976DE1D, 1978AT01, 1978DA1A).

Applied topics: (1975AU1C, 1979AN1L, 1979GR1E, 1979JA1F, 1979JUZU).

Ground state of 11B: (1974DE1E, 1974EN10, 1974SHYR, 1975AL19, 1975BE31, 1975EP02, 1976BR26, 1976DO1G, 1976FU06, 1976PH01, 1977AN21, 1977MA35, 1977PA25, 1977YO1D, 1978AN07, 1978HE1D, 1978ZA1D, 1979NI06).

μ = +2.68837 (2) (1978LEZA);

Q = 40.65 (26) mb [(1970NE05; theor.): adopted by (1978LEZA); see also (1968SC18, 1969SC34)].

1. 6Li(6Li, p)11B Qm = 12.218

Angular distributions have been measured for proton groups to states with Ex < 9.3 MeV at E(6Li) = 2.4 to 9.0 MeV (1966KI09). For γ-spectra and for τm see Tables 11.4 (in PDF or PS) and 11.5 (in PDF or PS). See also (1975AJ02) and (1976EP1A; astrophys.).

2. 7Li(α, γ)11B Qm = 8.665

Resonances for capture radiation are displayed in Table 11.6 (in PDF or PS). Results of studies of angular correlations, distributions and branching ratios are displayed in Tables 11.6 (in PDF or PS) and 11.4 (in PDF or PS): see (1968AJ02) for a discussion of the results. See also (1978SC1D; applied).

3. 7Li(α, n)10B Qm = -2.790 Eb = 8.665

Table 11.7 (in PDF or PS) displays the thresholds and resonances observed in this reaction. See also (1976SE1E), (1974LO1B, 1975AJ02, 1977LI19).

4. 7Li(α, p)10Be Qm = -2.5635 Eb = 8.665

See 10Be in (1979AJ01).

5. 7Li(α, d)9Be Qm = -7.1507 Eb = 8.665

See (1976LE1K) and 9Be in (1979AJ01).

6. 7Li(α, t)8Be Qm = -2.559 Eb = 8.665

Excitation functions have been measured for Eα = 14 to 25 MeV (t0) and 18 to 25 MeV (t1) (1972VA34, 1974DM01). See also (1976LE1K) and 8Be in (1979AJ01).

7. 7Li(α, α)7Li Eb = 8.665

The elastic scattering and the scattering to 7Li*(0.48) have been studied at many energies to Eα = 22.5 MeV: see (1968AJ02, 1975AJ02). Observed resonances are displayed in Table 11.8 (in PDF or PS). See also (1968AJ02, 1975AJ02, 1975VO1B), (1977BE51, 1977NI1A; theor.) and 7Li in (1979AJ01).

8. 7Li(6Li, d)11B Qm = 7.192

Angular distributions have been measured for E(7Li) = 3.3 to 5.95 MeV: see (1975AJ02). For γ-spectra and τm see Tables 11.4 (in PDF or PS) and 11.5 (in PDF or PS). See also 13C in (1981AJ01).

9. 7Li(7Li, t)11B Qm = 6.199

Angular distributions have been measured at E(7Li) = 2.10 to 5.75 MeV (1969CA1A: t0 → t3). See also (1976CAZJ). At E(7Li) = 79.6 MeV transitions are observed to several 11B states. 11Bg.s. is particularly strongly populated (1974CE06).

10. 9Be(d, γ)11B Qm = 15.8159

The 90° differential cross section has measured for Ed = 0.5 to 11.9 MeV: see (1975AJ02). The behavior of the γ0, γ1 and γ2+3 total cross sections of the angular distributions of these γ-rays indicate two resonances at Ed = 1.98 ± 0.05 and 3.12 ± 0.05 MeV with Γlab = 225 ± 50 and 320 ± 100 keV, corresponding to 11B*(17.43, 18.37). The higher resonance was not observable in the γ2 + γ3 cross section which was not measured beyond Ed = 2.5 MeV. The maximum γ0 cross section observed is 10.1 ± 3.5 μb at Ed ≈ 0.96 MeV (1971BA72). (1974DE39) observe resonant behavior in the 90° γ0 cross section at Ed ≈ 3.4 and 9.65 MeV (11B*(18.6, 23.7)) in addition to a wide structure at 4.7 MeV (11B*(19.7)). The angular distributions of γ0 from 11B*(18.6, 23.7) are typical of E1 transitions. The (d, γ0) reaction appears to proceed via excitation of the T = 1/2 component of the giant dipole resonance in 11B. See also (1974LO1B).

11. 9Be(d, n)10B Qm = 4.3607 Eb = 15.8159

The cross section follows the Gamow function for Ed = 70 to 110 keV (1955RA14). The fast neutron and γ-yield rise smoothly to Ed = 1.8 MeV except for apossible "resonance" at Ed ≈ 0.94 MeV. The fast neutron yield then remians approximately constant to 3 MeV: see (1968AJ02) for references. The exciation functions for n0 → n4, and n to 10B*(5.1, 6.57) have been measured for Ed = 14 to 16 MeV: no strong fluctuations are observed (1973PA14). Thick target yields are reported at Ed = 14.8, 18.0 and 23.0 MeV (1977LO10). Polarization measurements have been carried out at Ed = 0.9 to 5.5 MeV [see (1975AJ02)] and at 0.4 MeV (1977BA2K; n0, n1). See also (1975SA1C), (1977GR1F, 1977SA28, 1978BA1F, 1978HA1M, 1979CH11; applied) and 10B in (1979AJ01).

12. (a) 9Be(d, p)10Be Qm = 4.5872 Eb = 15.8159
(b) 9Be(d, α)7Li Qm = 7.151
(c) 9Be(d, t)8Be Qm = 4.5921

Measurements of proton yeilds have been carried out up to Ed = 6.0 MeV for p0 and p1 [see (1975AJ02)] and at 0.9 to 3.1 MeV (1975ZW01: σt, p0, p1). The p0 and p1 yields show a resonance at Ed = 750 ± 15 keV [11B*(16.43)], Γ ≈ 40 keV (1974AN01) and the p1 yield resonates at 1.85 MeV [11B*(17.33)], Γc.m. ≈ 1.0 MeV (1974FR02, 1975ZW01) and 2.3 MeV (1974FR02) [sharp state]. See also (1975AJ02) for other possible structures. Polarization of the protons have been measured at a number of energies for Ed = 1 to 21 MeV [see (1975AJ02)] and at Ed-bar = 12 MeV (1977BA39: TAP; p0, p1) and 15 MeV (1976DA15: VAP; p0, p1, p2+3, p4+5, p6, p7, p9). See also 10Be in (1979AJ01) and (1974BO35, 1974BO37, 1975BO20, 1975BO21; theor.).

The yields of α-particles [α0, α1], reaction (b), have been measured for Ed = 0.3 to 12.4 MeV [see (1975AJ02)] and at Ed = 2.25 to 3.10 MeV (1977SL02: α0, α1) and 12.17 to 14.43 MeV (1978TA04: α0, α1, α2, α4). (1974AN01) report a weak indication of the 0.75 MeV resonance, observed in the proton yield, in the α0 yield. See also 7Li in (1979AJ01).

The cross section for reaction (c) has been measured for Ed = 0.15 to 19 MeV [see (1968AJ02, 1975AJ02)] and at 0.9 to 2.5 MeV (1975BO1C; t0), 0.9 to 3.1 MeV (1975ZW01; t0) and 12.17 to 14.43 MeV (1978TA04; t0, t1). Polarization studies have been carried out at Ed-bar = 12 MeV (1977BA39: TAP; t0, t1) and 15 MeV (1976DA15; VAP; t0, t1). There is no clear evidence of resonance structure. See also 8Be in (1979AJ01). See also (1974CH1L).

13. 9Be(d, d)9Be Eb = 15.8159

Excitation functions for elastically scattered deuterons have been measured for Ed = 0.4 to 7.0 MeV [see (1975AJ02)] and for 12.17 to 14.43 MeV (1978TA12; also d1, d2). Polarization measurements involving the d0 group have been reported at Ed = 6.3 to 12.6 MeV [see (1975AJ02)] and at Ed-bar = 15 MeV (1976DA15: TAP; d to 9Be*(0, 2.43, 3.06)). See also 9Be in (1979AJ01).

14. 9Be(t, n)11B Qm = 9.5586

Angular distributions have been measured at Et = 1.1 to 1.7 MeV (1977MA1N; n0, n1, n2, n6, n8, n9 [at 1.3 MeV]).

15. 9Be(3He, p)11B Qm = 10.3224

Proton groups have been observed to a number of 11B states: see Table 11.9 (in PDF or PS). Angular distributions of many of these proton groups have been studied at E(3He) = 1.0 to 10.2 MeV [see (1968AJ02, 1975AJ02)] and at 3 to 6 MeV (1977LI1F) and 14 MeV (1977IR01; p0, p1). Gamma-ray branching ratios and multipolarities are displayed in Table 11.4 (in PDF or PS): see the discussion in (1968AJ02). See also (1966YO1A) and (1976EP1A; astrophys.).

16. 9Be(α, d)11B Qm = -8.0308

Angular distributions have been measured at Eα = 23.4, 24.7, 25.2 MeV (1975VA19; d0, d1 (at two higher energies only)), 27.0 MeV (1975PU01; d0 → d6) and 28.3 MeV (1965KA14; d0 → d3). The predominant L-transfers are L = 0, 2; 0; 0 for 11B*(0, 2.12, 5.02). The angular distribution for 11B*(4.45) is flat (1975PU01). See also (1976LE1K) and (1978ZE03; theor.).

17. (a) 9Be(6Li, α)11B Qm = 14.342
(b) 9Be(6Li, 2α)7Li Qm = 5.677
(c) 9Be(6Li, αp)10Be Qm = 3.114
(d) 9Be(6Li, αt)8Be Qm = 3.119

Angular distributions have been determined for seven α-groups at E(6Li) = 3 to 4 MeV: see (1968AJ02). Angular distributions have also been obtained at E(6Li) = 24 MeV to 11B*(0, 2.12) and to a number of unresolved levels with Ex ≤ 13.2 MeV (1968DA20, 1967CH34). See also (1977EL10; theor.).

The breakup reactions have been studied at E(6Li) = 3.5 MeV by (1968JA08): reaction (b) goes mainly via a sequential process process involving 11B*(10.3, 11.4, 12.6, 13.16, 13.5). The results for reaction (c) are not conclusive. 11B*(12.6, 13.16) may possibly contribute to reaction (d) (1968JA08).

18. (a) 9Be(7Li, αn)11B Qm = 7.092
(b) 9Be(9Be, 7Li)11B Qm = -0.880

See (1975AJ02).

19. 10Be(p, γ)11B Qm = 11.2287

The yield of ground state γ-rays has been measured at 90° for Ep = 0.6 to 6.3 MeV. Observed resonances are displayed in Table 11.10 (in PDF or PS). The four resonances correspond to states in 11B whose energies match well with those of the first four states in 11Be: T = 3/2. Several known T = 1/2 states in 11B are not observed in this reaction: see Table 11.3 (in PDF or PS) (1970GO04, 1973GO09). See also (1974LO1B).

20. 10B(n, γ)11B Qm = 11.4552

The thermal capture cross section is 0.5 ± 0.2 b (1973MU14). For a listing of the observed capture γ-rays see Table 11.12 (in PDF or PS) (1967TH05). For τm see Table 11.4 (in PDF or PS). The yield of γ-rays at En = 14 MeV shows a smaller fore-aft anisotropy than is observed in proton capture, suggesting that the forward peaking in the (p, γ) reaction is due mainly to direct rather than collective capture amplitudes (1975AR19). See also (1976MA1J).

21. 10B(n, n)10B Eb = 11.4552

The "free" neutron scattering cross section, σs-bar = 2.23 ± 0.06 b. The coherent scattering amplitude (bound) is a = +1.4 ± 0.5 fm (1973MU14). The total scattering cross section is constant at 2.23 ± 0.06 b for En = 0.7 to 10 keV and then rises to 2.97 b at En = 127 keV (1970AS10).

Total cross section measurements in the range En = 10 to 500 keV confirm the broad maximum near En = 0.23 MeV, originally suggested by (1951BO45) and also observed in the (n, α) cross section (1966MO09). At higher energies the total cross section shows broad maxima at En = 1.9 and 2.8 MeV (1951BO45) and at 4.3 MeV (1961FO07): see Table 11.12 (in PDF or PS). In the range En = 5.5 to 16 MeV σtot is constant at 1.5 b (1961FO07, 1979AU07). (1976GAYV) displays reported σtot measurements.

Polarization measurements (0.075 to 2.2 MeV and 2.63 MeV) and measurements of differential cross sections (0.075 to 4.4 MeV) by (1971LA10, 1973CO05, 1973HA64) have been analyzed using R-matrix calculations: the results are shown in Table 11.13 (in PDF or PS). They are consistent with results from 10B(n, n'γ) and 7Li(α, n).

Elastic differential cross sections have also been reported at En = 7.02 to 9.72 MeV [see (1975AJ02)] and at 4 to 8 MeV (1978KN01; n0, n1) and 14.1 MeV (1974HY01). See also 10B in (1979AJ01).

22. 10B(n, n')10B* Eb = 11.4552

The yield of 0.7 MeV γ-rays has been studied from threshold to En = 5.2 MeV: observed resonances are displayed in Table 11.12 (in PDF or PS) (1960DA08). Inelastic scattering cross sections for formation of various 10B states have been measured at a number of energies in the range En = 1.45 to 14.8 MeV: see (1975AJ02). See also 10B in (1979AJ01).

23. 10B(n, p)10Be Qm = 0.2265 Eb = 11.4552

The thermal cross section is < 0.2 b (1973MU14). See also (1976SL2A).

24. 10B(n, d)9Be Qm = -4.3607 Eb = 11.4552

See 9Be in (1979AJ01) and (1976SL2A).

25. (a) 10B(n, t)8Be Qm = 0.2314 Eb = 11.4552
(b) 10B(n, t)4He4He Qm = 0.3233

The cross section for reaction (b) has been measured for En = 1.4 to 8.2 MeV by (1961DA16). Fluctuations are observed at some of the resonant energies in the 10B(n, α) reaction: see Table 11.12 (in PDF or PS). For a display of the cross section see (1976GAYV). See also (1975BI07) and (1976LI1H, 1976SL2A).

26. 10B(n, α)7Li Qm = 2.790 Eb = 11.4552

The "recommended" value of the thermal isotropic absorption cross section is 3837 ± 9 b (1973MU14). The ground state branching for thermal neutrons is (6.308 ± 0.006)% (1967DE15), (6.699 ± 0.012)% (1979ST03). At En = 2 and 24 keV the values are (7.05 ± 0.16)% and (7.13 ± 0.15)%, respectively (1979ST03). The cross section for En = 10 eV to 200 keV is given by the expression:

13.837/ √E(square root of E) = 0.312 - 1.014 × 10-2√E(square root of E) +
fraction[(2.809 × 105/ √E(square root of E)[(170.3 - E)2 + 2.243 × 104]] b (1970SO1A).

See also (1974ST1F).

The total cross section for the (n, α) reaction is displayed in (1976GAYV). The cross section has been measured for En = 1.03 to 300 keV (1974CO1C; α1γ; no evidence for resonances), 4.70 to 630.64 keV (1978SC31; α1γ), 0.15 to 1.25 MeV (1975SE1H, 1976SE06; α0, α1; 0°, 120°; evidence for broad resonance at En ≈ 0.4 MeV in the α1 (0°) cross section) and at higher energies up to 14.8 MeV: see (1975AJ02) and Tables 11.12 (in PDF or PS) and 11.13 (in PDF or PS). At En = 0.79 MeV, the ratio for the α1tot yield is 0.66 ± 0.03 (1975LA08). See 7Li in (1979AJ01), (1975AJ02, 1976LI1H, 1976SL2A), (1975FR1C), (1976BO1L, 1976DA1F; applied) and (1975HA1L, 1977LO1C; theor.).

27. 10B(p, π+)11B Qm = -128.894

Angular distributions for proton capture to 11B*(0, 2.15 ± 0.10) have been measured at Ep = 168 to 186 MeV. The population of 11B*(4.45 + 5.02) and of unresolved higher states is also observed at 186 MeV but an attempt to observe T = 3/2 analogue states in 11B and 11N (the latter populated via (p, π-)) was unsuccessful (1974DA27, 1979HO09). Polarization measurements are reported by (1979PIZZ). See also (1977BE1X, 1979BE1W, 1979JO1C, 1979PI06, 1979SOZY) and (1979BO1V; theor.).

28. 10B(d, p)11B Qm = 9.2306

Reported proton groups are displayed in Table 11.14 (in PDF or PS). Angular distributions have been studied at many energies in the range Ed = 0.17 to 28 MeV [see (1968AJ02, 1975AJ02)] and at 0.75 to 2.5 MeV (1977AR12; p0 → p3). The lowest five levels are formed by ln = 1 except for 11B*(2.12) which appears to involve a spin-flip process. They are presumed to comprise the set 3/2-, 1/2-, 5/2-, 3/2-, 7/2- expected as the lowest p7 levels (a/K ≈ 4.0). 11B*(9.19, 9.27) [Jπ = 7/2+, 5/2+] show strong l = 0 stripping and are ascribed to capture of a 2s neutron by 10B: see (1968AJ02) for a listing of all the relevant references. Studies of pγ correlations are discussed in reaction 14 of (1968AJ02) and displayed in Table 11.4 (in PDF or PS) of this paper. See also 12C and (1975ZA06).

29. 10B(t, d)11B Qm = 5.1979

At Et = 5.5 MeV, deuteron groups are observed to the ground state of 11B and to states at Ex = 2.126, 4.449, 5.027, 6.769, 6.806 and 7.301 MeV (± 10 keV). All the angular distributions appear to be characteristics of ln = 1 (1961BA10). See also 13C in (1981AJ01).

30. 10B(α, 3He)11B Qm = -9.1226

Angular distributions have been measured at Eα = 56 MeV for the ground state transitions in this, and in the analog (α, t) reactions: the average ratio of the (α, 3He) to the (α, t) differential cross sections is 1.2 ± 0.1 (1969GA11).

31. (a) 10B(6Li, 5Li)11B Qm = 5.79
(b) 10B(7Li, 6Li)11B Qm = 4.205

At E(7Li) = 24 MeV angular distributions are reported to 11B*(0, 6.74, 8.92). 11B*(4.45, 5.02) are also populated. The (7Li, 6He) reaction [see reaction 16 in 11C] has also been studied (1977KO27). See also (1975AJ02).

32. 10B(13C, 12C)11B Qm = 6.5088

Total cross section measurements involving 11B*(4.45, 6.74) have been carried out for E(13C) = 8.0 to 12.7 MeV: S1S2 = 0.6 and 1.7, respectively (1975SE03). τm for 11B*(6.74) < 50 fsec (1975SE04): see Table 11.5 (in PDF or PS).

33. 10B(14N, 13N)11B Qm = 0.902

See (1975NA15, 1977MO1A). See also 13N in (1976AJ04, 1981AJ01), (1975AJ02) and (1975OS01; theor.).

34. 10B(16O, 15O)11B Qm = -4.209

See (1975NA15), 15O in (1976AJ04) and (1977OK1D; theor.).

35. (a) 10B(18O, 17O)11B Qm = 3.411
(b) 10B(19F, 18F)11B Qm = 1.024

Angular distributions have been measured at E(18O) and E(19F) = 20 and 24 MeV (1971KN05). See also (1975AJ02).

36. 11Be(β-)11B Qm = 11.508

11Be decays to 11B*(0, 2.12, 5.02, 6.79, 7.98, 9.88): see Table 11.15 (in PDF or PS) for the parameters of the observed β and γ transitions (1971AL07). Delayed α-particles are also observed with a total Iα of 3.0%/decay. These α-particles are not observed to be in coincidence with 478 keV γ-rays [upper limit = 5% for Eα > 0.3 MeV], suggesting that they result from the decay of 11B*(9.88) to 7Lig.s. (1971AL07).

37. 11B(γ, γ)11B

Mean gamma widths of low-lying states obtained by resonance scattering and transmission studies are listed in Table 11.16 (in PDF or PS) (1978KU12, 1979MO1M). The excitation energies of 11B*(2.13, 4.45, 5.02) are 2126.5 ± 1.5, 4446.4 ± 1.8 and 5.021.1 ± 1.8 keV (1977WE1C). See also (1975BR1F, 1979MOZX).

38. (a) 11B(γ, π-)11C Qm = -141.549
(b) 11B(γ, n)10B Qm = -11.4552
(c) 11B(γ, p)10Be Qm = -11.2287
(d) 11B(γ, d)9Be Qm = -15.8159
(e) 11B(γ, t)4He+4He Qm = -11.1319
(f) 11B(γ, α)7Li Qm = -8.665

For reaction (a) see (1975YE1A) and reaction 20 in 11C. The giant dipole resonance is shown to consist mainly of T = 1/2 states ion the lower energy region and of T = 3/2 sattes in the higher energy region by observing the decay to states in 10B and 10Be [reactions (b) and (c)] (1971PA10). See also (1979BR1D). Absolute measurements of the 11B(γ, all n) cross section from threshold to 35 MeV have been carried out by (1973HU09, 1976KN04): the cross section exhibits a main peak at Eγ = 25 to 28 MeV and weak shoulders at 13 and 16 MeV. The integrated cross section to 35 MeV is 69.1 ± 0.8 MeV · mb (1976KN04). See also (1975AD04) and (1974BU1A, 1976BE1H). For other structures reported in the (γ, n) and (γ, p) cross sections see (1975AJ02). The (γ, d0) cross section peaks at ≈ 19 MeV, lower than it would if T = 3/2 states were involved (1974DE01). The yield of 3.37 MeV γ-rays [from 10Be*(3.37), reaction (c)] has been measured for Ebs = 100 to 800 MeV (1975AD04). See also (1977BR1J). Double positron-electron pair production by 6.6 MeV γ-rays in boron has been studied by (1976RO1N). See (1959AJ76) for reactions (e) and (f). See also (1975AJ02) and (1978DI06).

39. 11B(e, e)11B Qm = -11.2287

The charge-scattering radius leads to an oscillator length parameter of 1.55 fm (1959ME24). Magnetic elastic scattering at θ = 180° shows strong M3 effects: the derived ratio of static M3/M1, 2.9 ± 0.2 fm2, suggests a j-j coupling scheme for 11Bg.s. (1966RA29). The quadrupole contribution to the elastic form factor is best accounted for by the undeformed shell model, Q = 3.72 (± 20%) fm2, r(r.m.s.) = 2.42 fm (1966IS1A, 1966ST12). See also (1979BE1N, muonic X-rays): < r2 >1/2 = 2.47 ± 0.04 fm. The excitation of 11B*(2.1, 4.4, 5.0, 8.6, 8.9) has been studied by (1975KA02: Ee = 52 to 90 MeV). The giant resonance region, centered at ≈ 18 MeV, is characterized by a lack of prominent features except for a pronounced peak at Ex = 13.0 ± 0.1 MeV (mixed M1 - E2) and a broad transverse group at Ex = 15.5 MeV (1975KA02).

Ground state transition widths are listed in Table 11.16 (in PDF or PS). For reaction (b) see (1975AJ02). See also (1974DE1E) and (1974WA1C, 1975DO1D, 1976DO1G, 1977TE02, 1977WA1G, 1978BO09, 1978TA1D; theor.).

40. 11B(n, n')11B*

Angular distributions of neutrons have been measured for En = 7.55, 9.72 and 14.1 MeV [see (1975AJ02)] and for En = 4 to 8 MeV (1976LA1C, 1976WH1A, 1977WH1A, 1977WHZZ; n0), 5.46, 5.62 and 6.00 MeV (1979KOZU; n1), 8 to 14 MeV (1978GL1D; n0 → n3) and 14.1 MeV (1974HY01; n0 → n3, n4+5). See also 12B.

41. (a) 11B(p, p')11B*
(b) 11B(p, 2p)10Be Qm = -11.2287
(c) 11B(p, pn)10B Qm = -11.4552

Observed proton groups are displayed in Table 11.17 (in PDF or PS). Angular distributions have been measured for Ep = 12 to 185 MeV [see (1975AJ02)] and at Ep = 6 MeV (1977SA1B; p0) and 30 MeV (1975CA08: to states shown in column 1 of Table 11.17 (in PDF or PS), except 11B*(8.92)). See also (1976AL1G, 1977CO1G). The analysis of the 3/2- → 1/2- transition [11B*(0 → 2.12)] at Ep-bar = 32 MeV shows less spin flip than predicted by DWBA (1977MO09). For reaction (b) see 10Be in (1979AJ01). For reaction (c) see (1977WA05). See also (1978AL1G) and (1976PH01, 1977PH02; theor.).

42. 11B(d, d)11B

The elastic scattering has been studied at Ed = 5.5 MeV (1971HIZF) and 11.8 MeV (1967FI07). See also (1974CH58; theor.).

43. 11B(t, t)11B

The elastic scattering has been studied at Et = 1.8 and 2.1 MeV (1969HE08, 1969SI12).

44. 11B(3He, 3He)11B

The elastic scattering has been studied has been studied at E(3He) = 8 to 74 MeV [see (1975AJ02)], at 17.5 and 40.0 MeV (1977SH09) and at 46.1 MeV (1979GO07). In the recent work angular distributions have also been studied for the 3He ions to 11B*(2.12, 4.45, 5.02, 6.74) (1977SH09). T = 3/2 states populated in this reaction are displayed in Table 11.18 (in PDF or PS). There is a weak indication also of a state at Ex = 14.51 MeV (1971WA21). See also (1975AJ02).

45. 11B(α, α)11B

Angular distributions have been reported at Eα = 28.3 to 29.0 MeV [see (1975AJ02)] and at 24 MeV (1976DE34: α0 → α3, α4+5). See also (1978ZE03; theor.).

46. 11B(6Li, 6Li)11B

The elastic scattering has been measured at E(6Li) = 28 MeV (1972BA52).

47. 11B(9Be, 9Be)11B

See (1975AJ02).

48. (a) 11B(10B, 10B)11B
(b) 11B(11B, 11B)11B

See (1976HI05). See also (1975AJ02).

49. 11B(12C, 12C)11B

The elastic scattering has been studied at E(11B) = 18.8 to 34.1 MeV (1978FR20) and 28 MeV (1969VO07, 1969VO10), at E(12C) = 15 to 24 MeV (1974BO15, 1975DU11) and at E(12C) = 87 MeV (1971LI11). The population of 11B*(2.12, 4.45, 6.79) and of 12C*(0, 4.43) are also reported: see (1969VO07). See also (1976ST12), (1978RO1D; astophys.) and (1975RE04, 1978AV1A, 1978VA1A; theor.).

50. 11B(14N, 14N)11B

The elastic scattering has been investigated at E(14N) = 41, 77 and 133 MeV (1971LI11).

51. 11B(16O, 16O)11B

The elastic scattering has been studied at E(16O) = 14.5 to 60 MeV [see (1975AJ02)] and at E(11B) = 115 MeV (1979BR03).

52. 11C(β+)11B Qm = 1.982

See 11C.

53. 12C(γ, p)11B Qm = -15.9569

The fraction of transitions to the ground and to excited states of 11B [and to 11C states reached in the (γ, n) reaction] has been measured at Ebs = 24.5, 27, 33 and 42 MeV: the ground state is predominantly populated. The population of analog states in the (γ, n) and (γ, p) reactions are similar: see 11C (1979ME17). See also (1979GO1N: Ebs = 21.7 to 31.0 MeV) and (1978KI03: Ebs to 120 MeV). Differential cross sections have been measured at Eγ = 60, 80 and 100 MeV (1976MA34, 1974FI17; p0, p1, p2 + p3 + p4). See also (1975MA1E, 1979KI1H), 12C and (1975AJ02).

54. 12C(π+, π+p)11B Qm = -15.9569

At Eπ+ = 100 MeV the reaction proceeds primarily to 11Bg.s. (1978CO02). At Eπ = 200 MeV the ratios for σnp for the first excited states in 11C/11B are 1.4 ± 0.2 for π- and 1/1.8 ± 0.2 for π+ (1979LI11). At Eπ+ = 60 to 300 MeV 11B*(4.45) [Jπ = 5/2-] is strongly populated, as is the analog state in the mirror reaction (1978MO01). See also reaction 25 in 11C.

55. 12C(e, ep)11B Qm = -15.9569

At Ee = 497 MeV 11B*(0, 2.1, 5.0) are populated: l = 1 (1976MO17). See also (1978SH14), (1975AJ02), 12C and (1975RO18, 1979BO07; theor.).

56. 12C(n, d)11B Qm = -13.7323

See (1974KI1A, 1975MC19, 1976KI1D).

57. 12C(p, 2p)11B Qm = -15.9569

Gross structure is seen in the summed proton spectrum corresponding to 11Bg.s. and to an excited state with Jπ = 1/2+ at Ex ≈ 19.5 MeV: see (1975AJ02). A high resolution experiment at Ep = 100 MeV shows groups corresponding to 11B*(0, 2.12, 4.45, 5.02, 6.79) (1977DE1M) [see (1975AJ02) for the earlier work]. See also (1977DE1L, 1978DE1P). At Ep = 100 MeV DWIA gives reasonably good agreement with angular correlation distributions (p0, p1, p2+3, p4+5) (1976BH02). See also 12C, (1976SI1A, 1977MC1F, 1977RO1E) and (1975PI1A, 1977RE1A, 1978HA35, 1979FA1B, 1979MA20; theor.).

58. 12C(d, 3He)11B Qm = -10.4634

Angular distributions of 3He ions have been measured for Ed = 20 to 50 MeV [see (1975AJ02)] and at Ed-bar = 29 MeV (1978CO13: to 11B*(0, 2.12, 4.45)) and Ed = 52 MeV (1968HI01, 1975MA41: to 11B*(0, 2.12, 4.45, 5.02, 6.74 + 6.79, 7.29)) and 80 MeV [(1974AS04: to 11B*(0, 4.45)), (1976DI05: to 11B*(0, 2.12, 5.02))]. Reported C2S for 11Bg.s. are 3.22 or 4.42 depending on the choice of parameters (1978CO13: Ed-bar = 29 MeV; see also (d, t) results in reaction 28 of 11C), and 2.98, 0.69, 0.31 for 11B*(0, 2.12, 5.02) (1975MA41: Ed = 52 MeV, DWBA). See also (1975LU07, 1976CHZH, 1977CH01; theor.).

59. 12C(t, α)11B Qm = 3.8571

Angular distributions have been measured for Et = 1 to 3.4, 10.1 and 13 MeV: see (1975AJ02). For electromagnetic transitions see Table 11.4 (in PDF or PS) (1968BE30).

60. (a) 12C(α, 5Li)11B Qm = -17.92
(b) 12C(α, αp)11B Qm = -15.9569

At Eα = 65 MeV, 11B*(0, 2.12, 6.74 + 6.79) are strongly populated (1978SA26). For reaction (b) see (1977YA1A, 1979KU08).

61. 12C(10B, 11C)11B Qm = -7.266

See reaction 31 in 11C (1975NA15, 1975VO05, 1976NA09).

62. 12C(12C, 13N)11B Qm = -14.014

The angular distribution involving the ground state transitions has been measured at E(12C) = 114 MeV (1974AN36). See also (1979HEZX).

63. 12C(14N, 15O)11B Qm = -8.660

See (1975AJ02) and 15O in (1981AJ01).

64. 12C(16O, 17O)11B Qm = -12.595

See (1977ZE1A; theor.).

65. 12C(19F, 20Ne)11B Qm = -3.1123

At E(19F) = 40, 60 and 68.8 MeV angular distributions involving 20Neg.s. + 11Bg.s., 20Ne*1.63 + 11Bg.s. and 20Neg.s. + 11B*2.12 (E = 68.8 MeV only) have been measured by (1972SC03). See also (1975PU02).

66. 13C(p, 3He)11B Qm = -13.1851

At Ep = 50.5 MeV, in addition to 11B*(0, 2.12, 4.45, 5.02, 6.74, 8.92), a state is observed at Ex = 12.94 ± 0.05 MeV, Γ = 350 ± 50 keV. Comparison of the angular distributions of the 3He and of the tritons [in the analog reaction] at Ep = 43.7 and 50.3 MeV lead to the assignments Jπ = 1/2-, T = 3/2 for this state and for 11C*(12.50): the strong proton and the weak α-decay are consistent with this assignment (1968CO26). See Table 11.18 (in PDF or PS) and (1974BE20). Angular distributions have been measured to 11B*(2.12, 4.45, 5.02), at Ep = 26.9 to 49.6 MeV [see (1975AJ02)] and at Ep-bar = 49.6 MeV (1974MA12; also to 11B*(6.74, 12.94)). See also reaction 34 in 11C for the mirror reaction, and see 14N in (1981AJ01).

67. 13C(d, α)11B Qm = 5.1680

Observed proton groups are displayed in Table 11.17 (in PDF or PS) (1970BR23). Angular distributions are reported at Ed = 0.41 to 14.1 MeV: see (1975AJ02). See also 15N in (1981AJ01).

68. 13C(17O, 19F)11B Qm = -4.865

See (1977CH22).

69. 14C(p, α)11B Qm = -0.7839

Angular distributions of the α0 → α3 groups have been measured at Ep = 18 MeV (1962BR34).

70. (a) 14N(n, α)11B Qm = -0.1580
(b) 14N(n, 2α)7Li Qm = -8.823

Angular distributions have been measured for En = 4.9 to 18.8 MeV [see (1975AJ02)] and at 13.9 MeV (1978MO09; α0 → α3). At En = 14.1 and 15.7 MeV various states of 11B with 8.9 < Ex < 14.5 MeV appear to be involved in the sequential decay to 7Li. Angular correlation results are consistent with Jπ = 7/2 and 5/2 for 11B*(9.19, 9.27) respectively (1971SC16). See also (1979SUZW), 7Li in (1979AJ01), 15N in (1981AJ01), and (1975AJ02).

71. 14N(10B, 13N)11B Qm = 0.902

See 13N in (1981AJ01).

72. 15N(α, 8Be)11B Qm = -11.0832

At Eα = 72.5 MeV angular distributions are reported to 11B*(0, 2.10 ± 0.04, 4.50 ± 0.07, 6.75 ± 0.04): S = 0.23, 0.12, 0.29, 0.45 (unresolved groups) (1974WO1C, 1976WO11).

73. 16O(d, 7Be)11B Qm = -16.039

At Ed = 80 MeV angular distributions have been measured to 11B*(0, 2.12, 4.45 + 5.02, 6.74 + 6.79 + 7.29) (1978OE1A).

74. 19F(12C, 20Ne)11B Qm = -3.1123

See 20Ne in (1978AJ03).