Information on masschains and nuclides
 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 Group Info Publications HTML General Tables Level Diagrams Tables of EL's NSR Key# Retrieval ENSDF Excitation Functions Thermal N Capt. G.S. Decays Half-Lives Table TUNL Dissertations NuDat at BNL Useful Links Citation Examples Home Sitemap Directory Email Us

 WWW TUNL    ## 12B (1959AJ76)

(See the Energy Level Diagram for 12B)

GENERAL: See also Table 12.1 [Table of Energy Levels] (in PDF or PS).

Theory: See (1956KU1A, 1958FR1C).

 1. 12B(β-)12C Qm = 13.376

The spectrum is complex: see 12C. The transition to 12Cg.s. is allowed; hence J(12B) = 1+.

 2. 6Li(7Li, p)12B Qm = 8.338

Three groups of protons are reported, corresponding to the ground state and to the excited states at 0.95 and 1.67 MeV. At E(7Li) = 2.0 MeV, θ = 90° (lab), the relative intensities are 1 : 1.1 : 0.8 (1957NO14). See also (1957NO17).

 3. 7Li(7Li, d)12B Qm = 3.311

See 14C.

 4. 9Be(α, p)12B Qm = -6.884

At Eα = 21.7 MeV, proton groups are observed corresponding to 12B*(0, 0.95, 1.65, 3.38, 3.82) (1951MC57, 1955RA41).

 5. 9Be(7Li, α)12B Qm = 10.463

See (1957NO17).

 6. 10B(t, p)12B Qm = 6.344

At Et = 0.90 MeV, proton groups are observed corresponding to 12B*(0.94, 1.65, 2.61, 3.37, 3.75, 4.46) (1955BI26: ± ≈ 0.1 MeV).

 7. 11B(n, γ)12B Qm = 3.365

 8. 11B(n, n)11B Eb = 3.365

The parameters of observed resonances at En = 0.43, 1.28, 1.78, 2.45 and 2.58 MeV are exhibited in Table 12.2 (in PDF or PS). The rise of the cross section at low energies may indicate a broad level formed by s-wave neutrons (1951BO45). The angular distributions of elastically scattered neutrons have been studied for En = 0.43 to 1.50 MeV by (1955WI25). It is found that the 0.43-MeV resonance has J = 2+, formed by p-waves, either all in channel spin 1 or all in channel spin 2. The 1.28 MeV resonance had J = 3-, formed by d-waves, with the level width of channel spin 2 about 10 times that of channel spin 1. Potential scattering at En = 1.5 MeV is nearly all s-wave: δ0 = -90° (1955WI25).

The total cross section for natural boron shows no sharp discontinuities for En = 4.4 to 5.6 MeV (σ ≈ 1.6 b) and for En = 7.8 to 8.6 MeV (σ ≈ 1.4 b) (1956BE98). The total cross section has also been measured for En = 6 to 9.7 MeV (1954NE1A) and from En = 14.1 to 18.0 MeV by (1952CO41, 1954CO16); see (1955HU1B). See also (1955HI1C, 1956LA1C, 1957LA14, 1958HU18). At En = 14.5 MeV the non-elastic cross section for natural boron is 0.64 ± 0.04 b (1956FL1B).

 9. (a) 11B(n, d)10Be Qm = -9.010 Eb = 3.365 (b) 11B(n, t)9Be Qm = -9.564 (c) 11B(n, α)8Li Qm = -6.636 (d) 11B(n, p)11Be Qm = -10.69

The cross section for reaction (c) decreases from 27 mb at En = 12.6 MeV to 16 mb at En = 20.0 MeV (1956AR21). At En = 14.1 MeV, the cross section for reaction (b) is 15 ± 5 mb (1958WY67). Reaction (a) has not been reported. See also (1954HE1B). For reaction (d) see 11Be.

 10. 11B(d, p)12B Qm = 1.138

Proton groups observed at Ed = 4.0 to 8.5 MeV are listed in Table 12.3 (in PDF or PS). No other groups are observed for Ex = 0 to 3.15 MeV with an intensity greater than 4% of the ground-state group, or from 3.15 to 3.5 MeV excitation with an intensity greater than 8% (1953EL12). See also (1954KH1A, 1955KH35). Angular distributions and absolute cross sections have been determined at Ed = 8 MeV. Analysis by stripping theory leads to the assignments indicated in Table 12.3 (in PDF or PS). Neutron capture probabilities are compared with expected single-particle values to eliminate certain spin possibilities (1953HO48). At Ed = 1.05 MeV, γ-rays with energy 0.94 and 1.64 MeV are observed with an intensity ratio of 2 : 1 (1954TH1B). See also (1955RA41, 1956KA1A, 1956TA07, 1957CH25, 1957CO59).

 11. 11B(t, d)12B Qm = -2.894

Not reported.

 12. 11B(α, 3He)12B Qm = -17.213

Not reported.

 13. 12C(n, p)12B Qm = -12.593

See (1948JE03).

 14. 12C(t, 3He)12B Qm = -13.358

Not reported.

 15. 13C(γ, p)12B Qm = -17.539

See 13C.

 16. 13C(d, 3He)12B Qm = -12.045

Not reported.

 17. 13C(t, α)12B Qm = 2.274

Not reported.

 18. 14C(n, t)12B Qm = -17.228

Not reported.

 19. 14C(p, 3He)12B Qm = -17.993

Not reported.

 20. 14C(d, α)12B Qm = 0.358 Q0 = 0.362 ± 0.0015 (1956DO41).  