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USNDP

11B (1990AJ01)


(See Energy Level Diagrams for 11B)

GENERAL: See also (1985AJ01) and Table 11.3 [Table of Energy Levels] (in PDF or PS).

Nuclear models: (1984ZW1A, 1985KW02, 1987KI1C, 1988OR1C, 1988WO04).

Special states: (1984ZW1A, 1985CH27, 1985GO1A, 1985HA1J, 1985SH24, 1987KI1C, 1988KW02, 1988ZH1B, 1989BA60, 1989OR02).

Electromagnetic transitions and giant resonances: (1983GM1A, 1984MO1D, 1984VA06, 1985GO1A, 1986ER1A, 1987KI1C, 1989BA60).

Astrophysical questions: (1982AU1A, 1982CA1A, 1984TR1C, 1985DW1A, 1985WA1K, 1987AR1J, 1987AU1A, 1987DW1A, 1987MA2C, 1987RO25, 1987WE1E, 1988AP1A, 1988BA86, 1988FE1A, 1988RE1B, 1989BO1F, 1989BO1M, 1989GU1Q, 1989JI1A).

Complex reactions involving 11B: (1984AI1A, 1984FI17, 1984HO23, 1984RE14, 1984SI15, 1984XI1B, 1985AG1A, 1985BE40, 1985BH02, 1985JA18, 1985MC03, 1985MO08, 1985PO11, 1985SH1G, 1985SI19, 1985WA1F, 1985WA22, 1986AV1B, 1986BA69, 1986BI1A, 1986BO1B, 1986CH2G, 1986CS1A, 1986HA1B, 1986MA19, 1986ME06, 1986MO15, 1986PO06, 1986RE13, 1986SA30, 1986SH2B, 1986UT01, 1986WA1H, 1986WE1C, 1987AN1A, 1987AR19, 1987BA1G, 1987BA38, 1987BE58, 1987BE55, 1987BO1K, 1987BU07, 1987DE37, 1987FE1A, 1987GR1O, 1987JA06, 1987KI05, 1987KO15, 1987LY04, 1987MA2F, 1987MU1D, 1987NA01, 1987OS1E, 1987PA01, 1987PO23, 1987SH23, 1987SI1C, 1987ST01, 1987TE1D, 1987TR05, 1987VI02, 1987WA09, 1987WE1D, 1987YA16, 1988BA53, 1988BL09, 1988CA06, 1988FE1A, 1988FO03, 1988GA12, 1988KA1L, 1988KHZX, 1988KI05, 1988KI06, 1988MI28, 1988MO1K, 1988PAZS, 1988RA10, 1988RU01, 1988SA19, 1988TE03, 1988UT02, 1989BL1D, 1989CEZZ, 1989HA43, 1989PA06, 1989PO06, 1989SA10, 1989SE03, 1989ST1G, 1989YO02).

Applications: (1984CA1D, 1986NO1C, 1988XI1B).

Muon and neutrino capture and reactions: (1983GM1A, 1984KO24, 1985MI1D, 1986KE1Q, 1987KU23, 1987SU06, 1987WE1E, 1988RA1E, 1989MI1G).

Pion and kaon capture and reactions (see also reactions 20, 30, and 48): (1983GE1C, 1983GM1A, 1984BA1T, 1984BA1U, 1985CO16, 1986PE05, 1986RO03, 1987BO1X, 1988AB05, 1988GIZU).

Antinucleon interactions: (1985BA51).

Hypernuclei: (1983SH1E, 1984CH1G, 1984SH1J, 1984ZH1B, 1985AH1A, 1985GA1E, 1985GR10, 1986AN1R, 1986BA3L, 1986BI1G, 1986DA1H, 1986DA1G, 1986DA1B, 1986DU1P, 1986FR1J, 1986GA33, 1986GA1H, 1986KI1K, 1986KO1A, 1986ME1F, 1986PO1H, 1986SZ1A, 1986YA1F, 1987MI38, 1987PO1H, 1988MA1G, 1988MO1L, 1988TA29, 1988TA14, 1989MI30).

Other topics: (1984PO11, 1985AN28, 1985SH24, 1986AN07, 1988KW02, 1988OR1C, 1989BA60, 1989OR02).

Ground-state properties of 11B: (1984AN1B, 1984ZI04, 1985AN28, 1985GO1A, 1985HA18, 1985FA01, 1985ZI05, 1986DO1E, 1986GL1A, 1986RO03, 1986WI04, 1987AB03, 1987FU06, 1987KI1C, 1988AR1I, 1988BI1A, 1988VA03, 1988WA08, 1988WO04, 1989SA10).

μ = +2.688637(2) nm (1978LEZA),
Q = 40.65(26) mb [see (1980AJ01)],
B(E2; 3/2- → 1/2-) = 2.6 ± 0.4 e2 · fm4 (1980FE07).

Mass of 11B: The mass excess of 11B has been measured to be 9303.09 ± 1.30 μu (1984EL05) [mass spectrometer]. The mass excess listed by (1988WA18) is 8668.2 ± 0.3 keV, and we adopt it.

See Table 11.4 [Electromagnetic Transitions in 11B] (in PDF or PS) here.

Isotopic abundance: (80.1 ± 0.2)% (1984DE53).

1. 6Li(6Li, p)11B Qm = 12.215

Angular distributions have been measured for the proton groups to the first eight states of 11B at E(6Li) = 2 to 16 MeV (1987DO05). For the earlier work see (1980AJ01). For excitation functions see 12C. See also (1987DO07).

2. 7Li(α, γ)11B Qm = 8.6637

Resonances for capture radiation are displayed in Table 11.5 (in PDF or PS). See also (1984YA1A, 1985CA41, 1988BU01, 1988CA26; astrophys.).

3. 7Li(α, n)10B Qm = -2.7905 Eb = 8.6637

The total cross section has been measured from threshold to Eα = 5.67 MeV [see also reaction 22]: a broad maximum at Eα ≈ 5.1 MeV (σmax = 40 mb) is observed (1984OL05). For the earlier work see Table 11.7 (in PDF or PS) in (1980AJ01) and Table 11.7 (in PDF or PS) in (1985AJ01). See also (1985CA41; astrophys.).

4. 7Li(α, t)8Be Qm = -2.5597 Eb = 8.6637

Excitation functions have been measured for Eα = 14 to 25 MeV (t0) and 18 to 25 MeV (t1): see (1980AJ01). See also 8Be in (1988AJ01) and (1987DM1C).

5. 7Li(α, α)7Li Eb = 8.6637

The elastic scattering and the scattering to 7Li*(0.48) have been studied at many energies to Eα = 22.5 MeV: see (1975AJ02, 1980AJ01, 1985AJ01). Observed resonances are displayed in Table 11.6 (in PDF or PS). For α - 7Li correlations see (1987PO03) and the "General" section. See also (1987BU27), (1987EL1B; applied) and (1985CH27; theor.).

6. 7Li(6Li, d)11B Qm = 7.189

Angular distributions have been measured for E(7Li) = 3.3 to 5.95 MeV: see (1975AJ02).

7. 7Li(7Li, t)11B Qm = 6.196

Angular distributions have been measured at E(7Li) = 2.10 to 5.75 MeV. At E(7Li) = 79.6 MeV transitions are observed to several 11B states. 11Bg.s. is particularly strongly populated. See (1975AJ02) for references.

8. 8Li(α, n)11B Qm = 6.6309

See (1988MA1U; astrophysics). See also (1988SA2Q, 1989BO1K).

9. 9Be(d, γ)11B Qm = 15.8153

The 90° γ0 differential cross section has been measured for Ed = 0.5 to 11.9 MeV: see (1975AJ02). The behavior of the γ0, γ1, and γ2+3 total cross sections and 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. Resonant behavior is observed 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.

10. 9Be(d, n)10B Qm = 4.3612 Eb = 15.8153

The cross section follows the Gamow function for Ed = 70 to 110 keV. The fast neutron and γ-yield rise smoothly to Ed = 1.8 MeV except for a possible "resonance" at Ed ≈ 0.94 MeV. The fast neutron yield then remains approximately constant to 3 MeV: see (1968AJ02) for references. The excitation 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: see (1975AJ02). Thick target yields for γ-rays have been measured at Ed = 48 to 170 keV: see (1985AJ01). Thick target yields are also reported at Ed = 14.8, 18.0 and 23.0 MeV: see (1980AJ01). Polarization measurements have been carried out at Ed = 0.4 to 5.5 MeV [see (1975AJ02, 1980AJ01)] and at Epol. d = 12.3 MeV: see (1985AJ01). See also 10B in (1988AJ01), (1985SM08, 1986BA40) and (1988ZVZZ; theor.).

11. (a) 9Be(d, p)10Be Qm = 4.5874 Eb = 15.8153
(b) 9Be(d, α)7Li Qm = 7.152
(c) 9Be(d, t)8Be Qm = 4.5919

Measurements of proton yields have been carried out at Ed up to 6.0 MeV for p0 and p1 [see (1975AJ02, 1980AJ01, 1985AJ01)]. The p0 and p1 yields show a resonance at Ed = 750 ± 15 keV [11B*(16.43), Γ ≈ 40 keV] and the p1 yield resonates at 1.85 MeV [11B*(17.33), Γcm ≈ 1.0 MeV] and 2.3 MeV [11B*(17.70), sharp]. See also (1975AJ02, 1985AJ01) for other possible structures. Polarization of the protons has been measured at Ed = 1 to 21 MeV [see (1975AJ02, 1980AJ01, 1985AJ01)] and at Epol. d = 2.0 to 2.8 MeV (1984DE46; VAP; p0, p1). See also 10Be in (1988AJ01) and (1984AN16).

The yield of α-particles (reaction (b)) has been measured for Ed = 0.3 to 14.43 MeV [see (1975AJ02, 1980AJ01, 1985AJ01)]. The 0.75 MeV resonance, observed in reaction (a), is weakly populated in the α0 yield. For polarization measurements see (1985AJ01) and (1984AN16: Ed = 2.0 to 2.8 MeV; α0+1; VAP). See also 7Li in (1988AJ01).

The cross section for reaction (c) has been measured for Ed = 0.15 to 19 MeV: see (1968AJ02, 1975AJ02, 1980AJ01). Polarization measurements are reported at Epol. d = 12 and 15 MeV [see (1980AJ01)] and at Epol. d = 2.0 to 2.8 MeV (1984AN16; t0). There is no clear evidence of resonance structure. See also 8Be in (1988AJ01).

12. 9Be(d, d)9Be Eb = 15.8153

Excitation functions for elastically scattered deuterons have been measured for Ed = 0.4 to 7.0 MeV and for 12.17 to 14.43 MeV (also d1, d2) [see (1975AJ02, 1980AJ01)]. Polarization measurements have been reported at Epol. d = 6.3 to 15 MeV [see (1975AJ02, 1980AJ01)] and at Ed = 2.0 to 2.8 MeV (1983DE50; d0; VAP). See also 9Be in (1988AJ01).

13. 9Be(t, n)11B Qm = 9.5580

Angular distributions have been measured at Et = 1.1 to 1.7 MeV (n0, n1, n2, n6, n8, n9): see (1980AJ01).

14. 9Be(3He, p)11B Qm = 10.3218

Observed proton groups are displayed in Table 11.7 (in PDF or PS). Angular distributions have been obtained at a number of energies in the range E(3He) = 1.0 to 38 MeV [see (1980AJ01, 1985AJ01)] and at 3 to 6 MeV (1981LI1C; nine groups; DWBA). It is suggested that the T = 1/2 strength is strongly fragmented (1982ZW02). See also (1985AJ01), 12C, (1985MC1C; applied) and (1988KH11; theor.).

15. 9Be(α, d)11B Qm = -8.0314

Angular distributions have been measured at a number of energies in the range Eα = 23.4 to 28.3 MeV [see (1980AJ01)] and at 30.2 MeV (1984VA07; d0 → d3). The predominant L-transfers are L = 0, 2; 0; 0 for 11B*(0, 2.12, 5.02). The angular distribution to 11B*(4.44) is flat at Eα = 27 MeV. At Eα = 48 MeV, 11B*(16.44, 17.69, 18.0, 19.15) are not excited suggesting that these states are rather pure T = 3/2 states (1982ZW02): see Table 11.7 (in PDF or PS).

16. 9Be(6Li, α)11B Qm = 14.3403

Angular distributions have been determined for seven α-groups at E(6Li) = 3 to 4 MeV, and at 24 MeV to 11B*(0, 2.12) and to a number of unresolved levels with Ex ≤ 13.2 MeV: see (1968AJ02, 1975AJ02). For the breakup reactions see (1975AJ02).

17. 10Be(p, γ)11B Qm = 11.2279

The yield of γ0 has been measured at 90° for Ep = 0.6 to 6.3 MeV. Observed resonances are displayed in Table 11.8 (in PDF or PS). T = 3/2 assignments are made for the states at Ex = 12.56, 12.91, 14.33 and 15.32 MeV whose energies match those of the first four states of 11Be [compare with the T = 3/2 states reported in 9Be(3He, p)11B - Table 11.7 (in PDF or PS)]. See also Table 11.15 (in PDF or PS). Several known T = 1/2 states in 11B are not observed in this reaction: see Table 11.3 (in PDF or PS).

18. 10Be(p, n)10B Qm = -0.2262 Eb = 11.2279

The reaction cross section has been measured for Ep = 0.89 to 1.93 MeV: the excitation of 11B*(12.56, 12.91) is reported ((1986TE1A) and G.M. Ter-Akopian, private communication; (1987ERZY)). See also (1988DU06; theor.).

19. 10B(n, γ)11B Qm = 11.4542
Q0 = 11454.1 ± 0.2 keV (1986KO19)

The thermal capture cross section is 0.29 ± 0.04 b (1986KO19). The observed capture γ-rays are displayed in Table 11.9 (in PDF or PS). See also (1988MU05; theor.).

20. 10B(n, n)10B Eb = 11.4542

The scattering amplitude (bound) a = -0.2 ± 0.4 fm, the total scattering cross section σ(free) = 2.23 ± 0.06 b (1983KO17). 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. For a display of cross sections and a listing of measurements see (1988MCZT).

Total cross section measurements in the range En = 10 to 500 keV show a broad maximum near En = 0.23 MeV, also observed in the (n, α) cross section. At higher energies the total cross section shows broad maxima at En = 1.9, 2.8 and 4.3 MeV: see Table 11.10 (in PDF or PS). In the range En = 5.5 to 16 MeV σtot is constant at 1.5 b.

Polarization measurements (0.075 to 2.2 MeV and 2.63 MeV) and measurements of differential cross sections (0.075 to 4.4 MeV) have been analyzed using R-matrix calculations: the results are shown in Table 11.11 (in PDF or PS). They are consistent with results from 10B(n, n'γ) and 7Li(α, n). See (1980AJ01) for references.

Elastic and inelastic cross sections have also been reported at En = 4 to 14.1 MeV [see (1980AJ01)], at En = 3.0 to 12.0 MeV (1986SAZR, 1987SAZX; prelim.), at 8.0 to 13.9 MeV (1982GL02) and at 10 to 17 MeV (1986MU08; also polarization measurements at 10 and 15 MeV; prelim.). The yield of 0.7 MeV γ-rays has been studied from threshold to En = 5.2 MeV: observed resonances are displayed in Table 11.10 (in PDF or PS). 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 (1988AJ01), (1986BAYL, 1986DR10), (1983GO1H, 1988MA1H), (1988RE09; computer code) and (1985CH27, 1988HAZT; theor.).

21. (a) 10B(n, p)10Be Qm = 0.2262 Eb = 11.4542
(b) 10B(n, t)4He4He Qm = 0.3226

The thermal cross section for reaction (a) is 6.4 ± 0.5 mb (1987LA16); that for reaction (b) is 4.47 ± 0.15 mb (1989CL01) [see also for other references], 7 ± 2 mb (1987KA32). The cross section for reaction (b) has also been studied for En = 1.4 to 8.2 MeV [see Table 11.10 (in PDF or PS) and (1968AJ02)] and 3 to 8 MeV (1986QA01; prelim.). For various breakup processes see (1984TU02). For a display of cross sections and a listing of measurements see (1988MCZT). See also (1985BO1D, 1988MA1H, 1988SUZY).

22. 10B(n, α)7Li Qm = 2.7905 Eb = 11.4542
The "recommended" value of the thermal isotopic absorption cross section is 3837 ± 9 b (1981MUZQ). The α01 branching for thermal neutrons is (6.723 ± 0.011)% [mean of values listed in (1985AJ01)]. At En = 2 and 24 keV the values are (7.05 ± 0.16)% and (7.13 ± 0.15)%, respectively (1979ST03).

The cross section for this reaction has been measured for En = 0.025 eV to 14.8 MeV [see (1975AJ02, 1980AJ01, 1985AJ01)]: for observed and deduced structures see Tables 11.10 (in PDF or PS) and 11.11 (in PDF or PS). For a display of cross sections and a listing of measurements see (1988MCZT). For a review see (1986CA28). "Detailed balance" [from 7Li(α, n) measurements] has led to the determination of the 10B(n, α0) cross section from 0 < En ≤ 0.78 MeV: two resonances are inferred at ER = 241 ± 18 and 493 ± 4 keV, with σR = 17 ± 3 and 112 ± 3 mb and Γ = 166 ± 40 and 194 ± 6 keV (1984OL05).

A study of the reaction involving polarized thermal neutrons and a polarized 10B target shows that the transition to 7Li*(0.48) proceeds almost totally through the J = 7/2 channel (1986KO19). The ratio of the 10B(n, α) cross section to the 6Li(n, t) cross section has been measured from En ≈ 1 to 45 eV (1986CA29; prelim.).

Parity violation has been studied using polarized thermal neutrons: the P-odd asymmetries for the transitions to 7Li*(0, 0.48) are < 3.7 × 10-6 and < 6.1 × 10-7, respectively (1986ER05): see also (1983VE10), and (1985AJ01) for the earlier work. See also 7Li in (1988AJ01), (1984AL1M, 1984XI1A, 1986CO1M, 1986DR1G, 1986GR1F, 1986OL1B, 1986WI1B; applied) and (1986AB1E, 1986MI1G, 1988MA1H).

23. 10B(p, π+)11B Qm = -128.897

Angular distributions have been obtained at Ep = 168 to 800 MeV to several states of 11B [see (1980AJ01, 1985AJ01)] as have cross sections for π+ production near threshold. At Epol. p = 200 to 260 MeV, angular distributions and analyzing powers have been measured for the groups to 11B*(0, 2.12) (1985ZI04).

24. 10B(d, p)11B Qm = 9.2296

Reported proton groups are displayed in Table 11.14 (in PDF or PS) of (1980AJ01). Angular distributions have been studied at many energies in the range Ed = 0.17 to 28 MeV [see (1968AJ02, 1975AJ02, 1980AJ01)]. 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.

25. (a) 10B(t, d)11B Qm = 5.1969
(b) 10B(α, 3He)11B Qm = -9.1236

See (1968AJ02, 1975AJ02).

26. (a) 10B(7Li, 6Li)11B Qm = 4.204
(b) 10B(9Be, 8Be)11B Qm = 9.7888
(c) 10B(13C, 12C)11B Qm = 6.5078

See (1980AJ01, 1985AJ01).

27. 11Be(β-)11B Qm = 11.506

11Be decays to many states of 11B: see Table 11.12 (in PDF or PS) for the observed β- and γ-transitions (1982MI08). 11B*(9.88) decays via α-emission for 7Li*(0, 0.48) with branching ratios (87.4 ± 1.2)% and (12.6 ± 1.2)%, respectively (1981AL03). A study of the βν angular correlation in the first-forbidden decay of 11Be to the 1/2- state 11B*(2.12) has been performed: the β-transition is dominated by rank-0 matrix elements and is of interest as a test of meson-exchange effects: see (1985AJ01). See also (1988WA1E).

28. (a) 11B(γ, n)10B Qm = -11.4542
(b) 11B(γ, p)10Be Qm = -11.2279
(c) 11B(γ, d)9Be Qm = -15.8153
(d) 11B(γ, t)8Be Qm = -11.2234

The giant dipole resonance is shown to consist mainly of T = 1/2 states in the lower energy region and of T = 3/2 states in the higher energy region by observing the decay to states in 10B and 10Be [reactions (a) and (b)]. Absolute measurements of the 11B(γ, all n) cross section have been carried out from threshold to 35 MeV: 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: see (1980AJ01) and (1988DI02). See also (1984AL22). 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. The yield of 3.37 MeV γ-rays [from 10Be*(3.37), reaction (b)] has been measured for Ebs = 100 to 800 MeV. See also (1984AL22, 1986AL24). For reaction (d) see (1986AL24). See (1980AJ01, 1985AJ01) for references and for other photonuclear processes. See also (1985CH27, 1985GO1A, 1987KI1C, 1987LU1B, 1988DU04; theor.).

29. 11B(γ, γ)11B

Widths of excited states are displayed in Table 11.13 (in PDF or PS). See also (1984AL22, 1988BEYY).

30. (a) 11B(e, e)11B
(b) 11B(e, ep)10Be Qm = -11.2279

< r2 >1/2 = 2.43 ± 0.11 fm (1986DO1E; prelim.).

[See also unpublished result in (1980AJ01).]

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.. The quadrupole contribution to the elastic form factor is best accounted for by the undeformed shell model, Q = 3.72 (± 20%) fm2, < r2 >1/2 = 2.42 fm. See (1980AJ01) for references. A recent study of the elastic scattering for q = 2.0 to 3.9 fm-1 is reported by (1988HI02): the M3 component is dominant in the elastic form factor for q > 1.5 fm-1.

The excitiation of 11B*(2.1, 4.4, 5.0, 8.6, 8.9) has been studied. 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. At Ee = 121, 186 and 250 MeV form factors (and B(Eλ)↑) are obtained for 11B*(4.4, 6.7, 8.5, 8.9, 13.00 ± 0.15) and the excitation of 11B*(14.50 ± 0.15, 16.7 ± 0.2) is also reported: see (1985AJ01). See also (1984DO20, 1987DE43).

For Γγ0 see Table 11.13 (in PDF or PS). For reaction (b) see (1975AJ02). See also (1985KE1E, 1986HA1M, 1986KE1F, 1987AL1M, 1987DO12; theor.).

31. 11B(π+, π+)11B

The proton matter distribution in 11Bg.s. has a radius of 2.368 ± 0.021 fm, assuming that for 12C to be 2.44 fm. The result is not sensitive to the details of the optical-model calculations (1980BA45; Eπ+ = 38.6 and 47.7 MeV). See also the "General" section.

32. 11B(n, n)11B

Angular distributions have been reported for En = 75 keV to 14.1 MeV [see (1980AJ01, 1985AJ01)] and at En = 8.0 to 13.9 MeV (1982GL02; n0 → n3). Recent work (prelim.) is reported to 17 MeV (1986MU08; n0). See also 12B, (1985WA1P) and (1988HAZT; theor.).

33. (a) 11B(p, p)11B
(b) 11B(p, 2p)10Be Qm = -11.2279
(c) 11B(p, pn)10B Qm = -11.4542

Observed proton groups are displayed in Table 11.14 (in PDF or PS). Angular distributions have been measured for Ep = 6 to 185 MeV [see (1980AJ01)] and at 1 GeV (1985AL16). For reactions (b) and (c) at 1 GeV see (1985BE30, 1985DO16). For pion production see (1988AB05). See also 12C, (1988BE2B), (1985MUZZ) and (1985AJ01).

34. 11B(d, d)11B

Elastic scattering has been studied at Ed = 5.5 and 11.8 MeV: see (1980AJ01).

35. 11B(t, t)11B

The elastic scattering has been studied at Et = 1.8 and 2.1 MeV: see (1980AJ01).

36. 11B(3He, 3He)11B

The elastic scattering has been studied at E(3He) = 8 to 74 MeV: see (1975AJ02, 1980AJ01). At E(3He) = 17.5 and 40 MeV angular distributions have also been studied for the 3He ions to 11B*(2.12, 4.44, 5.02, 6.74). T = 3/2 states observed in this reaction are displayed in Table 11.15 (in PDF or PS). See also (1985AJ01). There is a weak indication of a state at Ex = 14.51 MeV: see (1975AJ02). See also (1986JA14) and (1987TR01; theor.).

37. 11B(α, α)11B

Angular distributions have been reported at Eα = 24 to 31.2 MeV: [see (1975AJ02, 1980AJ01, 1985AJ01)] and at 48.7 and 54.1 MeV (1987AB03; α0). See also (1983SA07) and (1985SH1D; theor.).

38. (a) 11B(6Li, 6Li)11B
(b) 11B(7Li, 7Li)11B

The elastic scattering has been studied at E(6Li) = 28 MeV: see (1975AJ02). At E(7Li) = 34 MeV angular distributions have been reported to 11B*(0, 2.12, 4.44, 5.02, 6.74, 7.29, 8.92) (1987CO02, 1987CO16). See also (1988HN01; theor.).

39. (a) 11B(9Be, 9Be)11B
(b) 11B(10B, 10B)11B
(c) 11B(11B, 11B)11B

For reaction (a) see (1985DA17, 1986CU02). For fusion cross sections (reactions (b) and (c)) see (1989SZ01). See also (1975AJ02, 1980AJ01), (1985BE1A, 1985CU1A) and (1984HA43, 1986RO12; theor.).

40. (a) 11B(12C, 12C)11B
(b) 11B(13C, 13C)11B

The elastic scattering has been studied at E(11B) = 18.8 to 50 MeV and at E(12C) = 15 to 24 MeV and 87 MeV [see (1980AJ01, 1985AJ01)] as well as at E(11B) = 10.4, 12.4 and 14.6 MeV (1985JA01), at Ecm = 25 MeV (1986MA13), at E(11B) = 42.5 to 100 MeV (1985MA10) and at E(12C) = 65 MeV (1985GO1H; prelim.; involving various states of 12C) [see 12C]. The population of 11B*(2.12, 4.44, 6.79) is also reported. For yields, fusion and breakup studies see (1985AJ01) and (1985MA10, 1986MA13). For reaction (b) see (1984DEZX, 1984HAZK; prelim.). See also (1987PO15), (1984FR1A, 1984HA53, 1985BE1A, 1985CU1A, 1988MA07), (1982BA1D, 1985BA1T; astrophys.) and (1984HA43, 1984IN03, 1985KO1J, 1986BA69, 1986HA13; theor.).

41. 11B(14N, 14N)11B

The elastic scattering has been investigated at E(14N) = 41, 77 and 133 MeV: see (1975AJ02, 1985AJ01). See also (1985BE1A, 1985CU1A) and (1984HA43; theor.).

42. (a) 11B(16O, 16O)11B
(b) 11B(18O, 18O)11B

The elastic scattering in reaction (a) has been studied at E(16O) = 14.5 to 60 MeV and at E(11B) = 41.6, 49.5 and 115 MeV. The elastic scattering in reaction (b) is reported at E(11B) = 115 MeV. For references see (1975AJ02, 1980AJ01, 1985AJ01).

43. 11B(20Ne, 20Ne)11B

The elastic angular distribution has been studied at E(11B) = 115 MeV: see (1985AJ01).

44. (a) 11B(24Mg, 24Mg)11B
(b) 11B(25Mg, 25Mg)11B
(c) 11B(26Mg, 26Mg)11B
(d) 11B(27Al, 27Al)11B
(e) 11B(28Si, 28Si)11B

The elastic angular distributions for reactions (a) to (d) have been studied at E(11B) = 79.6 MeV: see (1985AJ01). See also (1987PO15). For reaction (e) see (1984TE1A).

45. (a) 11B(40Ar, 40Ar)11B
(b) 11B(40Ca, 40Ca)11B

For reaction (a) see (1985MO1K; prelim.). Angular distributions have been reported in reaction (b) at E(11B) = 51.5 MeV to 11B*(0, 2.12): see (1985AJ01).

46. 11C(β+)11B Qm = 1.982

See 11C.

47. (a) 12C(γ, p)11B Qm = -15.9572
(b) 12C(e, p)11B Qm = -15.9572

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 = 21.7 to 42 MeV: the ground state is predominantly populated: see (1980AJ01). The predominant population of 11Bg.s. has also recently been observed at Eγ = 28 MeV (1989FE01). Analog states are populated similarly in the (γ, n) and (γ, p) reactions. Angular distributions for the protons to several states of 11B have been measured at Eγ = 21.7 → 31 MeV and at 60, 80 and 100 MeV [see (1980AJ01, 1985AJ01)] as well as in the giant resonance region [see 12C] (1986KE06; p0) and at 60 MeV (1988SH08; p to 11B*(0, 2.12, 5.0, 6.8 (unres.)). The relative population of 11B*(6.8) is much greater than that reported in (e, ep) (1988SH08). Spectra have also been studied by (1986AN25, 1986MC15). For reaction (b) see (1985AJ01). See also 12C, (1987VO08) and (1984BO18, 1987GO37, 1988OR02, 1989PIZZ; theor.).

48. 12C(e, ep)11B Qm = -15.9572

(1988VA09) have studied the l = 1 knockout to 11B*(0, 2.12, 5.02) at Ee = 284.5 to 481.1 MeV. One-third to one-half of the sum-rule strength predicted by the independent-particle shell model is observed. See (1988VA09) also for a review of spectroscopic factors. 11B*(4.44) is not observed: the two-step processes which are necessary to excite it in this reaction appear to be weak (1985VA16, 1988VA21). Weak transitions have been studied to states at Ex = 6.751 (unresolved), 7.278, 7.954, 8.61, 9.820 (± 25 keV, except ± 50 keV for 8.61) and to a broad structure at 11.5 MeV. l = 0 and 1 are suggested for the structures at 9.8 and 11.5 MeV (1988VA21; also Sα). See also the earlier work in (1985VA05). The effects of the nuclear medium have been studied by (1986VA17, 1987UL03, 1988VA09): see 12C. See 12C and (1984CA34, 1987CAZY) for the decay of 12C states to 11B*(0, 2.12). See also (1985DE56, 1986DE1U, 1986LA1T, 1988HA12, 1989BOZZ) and (1984LA16, 1985CA32, 1985LA1F, 1986DE05, 1987BL10, 1987GOZO, 1987VA15, 1988HO10, 1988SU02, 1989RY03; theor.).

49. 12C(π+, π+p)11B Qm = -15.9572

At Eπ+ = 100 to 200 MeV the reaction proceeds primarily to 11Bg.s.. 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+. At Eπ+ = 60 to 300 MeV 11B*(4.44) [Jπ = 5/2-] is strongly populated as is the analog state in the mirror reaction: see (1980AJ01, 1985AJ01) for references. At Eπ± = 220 MeV the quasi-elastic nature of the scattering has been studied by (1984FA11). See also the studies by (1984ZI1B, 1987HU02), 12C, (1984GO1F), (1986CH1J) and (1985CO03; theor.).

50. 12C(n, d)11B Qm = -13.7326

See (1985FR07, 1987FR16, 1989ROZW) and in 13C in (1986AJ01, 1991AJ01). See also (1986DO12, 1988YOZX).

51. 12C(p, 2p)11B Qm = -15.9572

At Ep = 98.7 MeV groups are observed to 11B*(0, 2.12, 4.44, 5.02, 6.79). DWIA lead to relative spectroscopic factors of 2.0, 0.37, 0.15, 1.08, 0.25 for these states. No evidence is seen for multistep reaction processes which would be necessary to populate 11B*(4.44, 6.74): see (1985AJ01). At Ep = 1 GeV the separation energy between 6 and 14 MeV broad 1p3/2 and 1s1/2 groups is 18 MeV (1985BE30, 1985DO16). See also (1984VD01, 1986VDZY; Ep = 50 MeV), (1989TEZZ) and (1985DE56, 1987VD1A).

52. 12C(d, 3He)11B Qm = -10.4637

Angular distributions of 3He ions have been measured for Ed = 20 to 80 MeV and spectroscopic factors have been derived for 11B*(0, 2.12, 5.02): see (1975AJ02, 1980AJ01, 1985AJ01).

53. 12C (t, α)11B Qm = 3.8568

Angular distributions have been measured at Et = 33 and 38 MeV to 11B*(0, 2.12, 4.44, 5.02, 6.74, 7.29, 7.98, 8.56). As expected, the 5/2- and 7/2- states 11B*(4.44, 6.74) are populated by two-step processes. The best Jπ value for 11B*(8.56) is 3/2- but this assumes some direct population which may not be the case (1987FO21, 1988SI08) [see for spectroscopic factors]. For the earlier work see (1975AJ02).

54. 12C(α,5Li)11B Qm = -17.92

See (1987GA20) and (1985AJ01).

55. 12C(6Li, 7Be)11B Qm = -10.351

At E(6Li) = 93 MeV, 11B*(0, 2.12, 5.0, 6.8, 8.9) are populated (1988BUZI; prelim.). See also (1986GL1E; prelim.).

56. 12C(12C, 13N)11B Qm = -14.0134

Angular distributions involving 11Bg.s. have been measured at E(12C) = 93.8 and 114 MeV: see (1985AJ01). See also (1987WIZW).

57. 12C(13C, 14N)11B Qm = -8.4066

See (1987AD07, 1988VO08) and 14N in (1991AJ01). See also (1989VO1D).

58. 12C(19F, 20Ne)11B Qm = -3.108

At E(19F) = 40, 60 and 68.8 MeV angular distributions involving 11B*(0, 2.12) and 20Ne*(0, 1.63) have been measured: see (1980AJ01). See also (1986HE1A, 1988DI08; theor.).

59. 13C(p,3He)11B Qm = -13.1855

At Ep = 50.5 MeV, in addition to 11B*(0, 2.12, 4.44, 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 [to the analog state] at Ep = 43.7 and 50.5 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: see Table 11.15 (in PDF or PS). Angular distributions have been measured at Ep = 26.9 to 49.6 MeV involving the above states except for 11B*(8.92) and at Epol. p = 65 MeV (to 11B*(0, 2.12)): see (1975AJ02, 1980AJ01, 1985AJ01). See also 14N in (1986AJ01) and (1985HA1J).

60. 13C(d, α)11B Qm = 5.1677

Observed proton groups are displayed in Table 11.14 (in PDF or PS). Angular distributions are reported at Ed = 0.41 to 14.1 MeV: see (1975AJ02). See also (1985HA1J).

61. 14C(p, α)11B Qm = -0.7842

Observed states are displayed in Table 11.14 (in PDF or PS) (1985AR03). It is suggested 11B*(12.92, 15.29, 16.50, 19.07) are T = 3/2, negative-parity states. Spectroscopic factors have also been derived (1985AR03).

62. (a) 14N(n, α)11B Qm = -0.1583
(b) 14N(n, 2α)7Li Qm = -8.8220

Angular distributions have been measured for En = 4.9 to 18.8 MeV [see (1975AJ02, 1980AJ01, 1985AJ01)] and at 12.2, 14.1 and 18.0 MeV (1986RU1B; α0, α1). 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 J = 7/2 and 5/2 for 11B*(9.19, 9.27) respectively: see (1975AJ02). See also (1985HA1J).

63. 14N(p, p3He)11B Qm = -20.7361

See (1986VDZY; prelim.; 50 MeV).

64. 16O(d, 7Be)11B Qm = -16.038

At Ed = 80 MeV angular distributions have been measured to 11B*(0, 2.12, 4.44 + 5.02, 6.74 + 6.79 + 7.29): see (1980AJ01).