Information on mass chains 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

GENERAL: See also (1980AJ01) and Table 12.2 [Table of Energy Levels] (in PDF or PS).

Model calculations:(1980HA35, 1983SH38, 1984VA06).

Special states:(1980HA35, 1980OK01, 1981SE06, 1984VA06).

Complex reactions involving ¹²B:(1979AL22, 1979BO22, 1980MA24, 1980NA1C, 1980TR1F, 1980WI1L, 1981GR08, 1981ME13, 1981MO20, 1982GO1E, 1982LY1A, 1983EN04, 1983MA06, 1983OL1A, 1983SA06, 1983WI1A, 1984GR08, 1984HI1A).

Muon and neutrino capture and reactions (See also reaction 17.):(1979HW02, 1979KI1G, 1979PA19, 1979PR1C, 1979WU10, 1980MU1B, 1981AM05, 1981CI05, 1981EI1A, 1981GI08, 1981PA1G, 1981RO05, 1981RO15, 1982BO1W, 1982MI05, 1982RO1F, 1982RO13, 1983FU17, 1983GM01, 1983KU1L, 1983NO12, 1984BO1M).

Pion and kaon capture and reactions (See also reactions 13 and 16.):(1978GO18, 1979AL21, 1980AR01, 1980DU20, 1980HA18, 1980OH07, 1980RA05, 1980SO05, 1980TR1A, 1981DE01, 1981DE1U, 1981DO1F, 1981DU1H, 1981EI01, 1981RA16, 1982AR06, 1982BE1D, 1982BO11, 1982GO01, 1982GOZX, 1982RA28, 1983BE1A, 1983CO1L, 1983DE2G, 1983GI08, 1983HS01, 1983MO1J, 1983SH2C, 1983TR1J).

Hypernuclei:(1978SO1A, 1979BU1C, 1980KI1F, 1982KA1D, 1983CH1T, 1983CO1L, 1983DO1B, 1983FE07, 1983HS01, 1983SH38).

Other topics:(1979HA58, 1979NO05, 1981DO1F, 1981SE06, 1981WA1J, 1982NG01).

Ground-state properties of ¹²B, including its polarization:(1980FU1G, 1980TR1F, 1981AV02, 1981KO1D, 1981MI1C, 1981MI1D, 1981NE1B, 1981SE06, 1982BA37, 1982DE16, 1982NG01, 1982RE01, 1983ANZQ, 1983FU15, 1983KU1L, 1983MI28, 1983NO05, 1983TA1K, 1984KU07).

1. 12B(β-)12C

Qm = 13.369

The half-life of ¹²B is 20.20 ± 0.02 msec (1978AL01). The decay is complex. ¹²B decays to ¹²C*(0, 4.4, 7.7, 10.3): see Table 12.14 (in PDF or PS). The transitions to ¹²C*(0, 4.4) are allowed: hence the J^π of ¹²B_g.s. is 1⁺. See also (1983AD1B) and (1979HW03, 1979KI1G, 1979MA31, 1979NO01, 1979PR1C, 1979RH1A, 1980OK01, 1980SY02, 1981CH1B, 1981HO06, 1981KO27, 1982GU09, 1983MO1N; theor.).

2. 6Li(7Li, p)12B

Qm = 8.334

Eleven groups of protons are reported to known states of ¹²B. Angular distributions have been measured at E(⁶Li) = 3.5 to 5.95 MeV. The distributions are generally featureless: see (1975AJ02).

3. 7Li(7Li, d)12B

Qm = 3.308

Angular distributions for d₀, d₁, d₂, d₃₊₄ have been measured at E(⁷Li) = 2.10 to 5.75 MeV. See also (1975AJ02) and (1981KO1D).

4. 9Be(t, n)11B

Qm = 9.5589

Eb = 12.928

Thirteen resonances have been reported corresponding to 13.6 < E_x < 14.7 MeV: see Table 12.3 (in PDF or PS) in (1975AJ02). The yield of 2.12 MeV γ-rays has been measured for E_t = 1.5 to 3.3 MeV and E(⁹Be) = 10 to 16 MeV by (1983MI08): no resonances are observed.

5. (a) 9Be(t, p)11Be	Qm = -1.167	Eb = 12.928
(b) 9Be(t, d)10Be	Qm = 0.5548
(c) 9Be(t, t)9Be
(d) 9Be(t, α)8Li	Qm = 2.927
(e) 9Be(t, 6He)6Li	Qm = -5.380

Yields of elastically scattered tritons have been measured for E_t = 0.60 to 2.1 MeV: see (1975AJ02). Differential cross sections and analyzing power for elastic tritons have been measured at E_{pol. t} = 15 and 17 MeV (1978SC02). The yields of 0.32 MeV (reaction (a)), 0.98 MeV (reaction (d)) and 0.48 MeV γ-rays (from the (t, αn) reaction) have been studied for E_t = 1.5 to 3.3 MeV and E(⁹Be) = 10 to 16 MeV: no resonances are observed (1983MI08). The yields of α₀ and α₁ have also been reported for E_t = 0.52 to 1.70 MeV: see (1975AJ02). The analyzing powers of the reactions leading to ⁶He_g.s. and ⁶Li*(0, 3.56) have been measured at E_{pol. t} = 17 MeV (1979FL03). See also (1983CE01), (1981ME1D, 1983WE02; theor.), ¹¹Be, and ⁶He, ⁶Li, ⁸Li and ⁹Be in (1984AJ01).

6. 9Be(α, p)12B

Qm = -6.886

At E_α ≈ 35 MeV (1981HAZV) report the excitation of two sharp and strong groups to ¹²B*(10.6, 10.9). See also (1983AU1C).

7. 9Be(7Li, α)12B

Qm = 10.460

Observed α-particle groups are displayed in Table 12.3 (in PDF or PS). Angular distributions have been measured at E(⁷Li) = 3.3 to 6.2 MeV, at 20 MeV and at 30.3 MeV: see (1975AJ02, 1980AJ01). At E(⁷Li) = 20 MeV angular distributions to the first seven states are rather featureless and have approximate symmetry about 90°. The integrated cross sections go as 2J_f + 1 consistent with a compound nucleus mechanism for the transitions populating the low-lying states of ¹²B. It is suggested that the sharp states of ¹²B at high excitation energies correspond to states of high angular momenta with cluster configurations.

8. (a) 10Be(d, p)11Be	Qm = -1.722	Eb = 12.373
(b) 10Be(d, α)8Li	Qm = 2.372

The cross sections for production of ⁸Li (reaction (b)) and of ¹¹Be (reaction (a)) have been measured for E_d = 0.67 to 3.0 MeV and 2.3 to 12 MeV, respectively: the yields for both reactions vary smoothly with energy. No resonances are observed: see (1975AJ02).

9. 10B(t, p)12B

Qm = 6.342

Observed excited states are displayed in Table 12.3 (in PDF or PS). Angular distributions have been studied at E_t = 10 and 23 MeV: see (1980AJ01).

10. 11B(n, γ)12B

Qm = 3.369

The thermal-neutron capture cross section is 5.5 ± 3.3 mb [see (1981MUZQ)]. The capture cross section shows resonances at E_n = 20.8 ± 0.5 keV and at 0.43, 1.03, 1.28 and 1.78 MeV, with Γ_γ = 25 ± 8 meV and 0.3, 0.3, 0.2 and 0.9 eV (± 50%): see Table 12.4 (in PDF or PS) and (1968AJ02). See also (1980DO1C; astrophys.).

11. 11B(n, n)11B

Eb = 3.369

The thermal (bound) scattering cross section is 3.9 ± 0.2 b. The scattering amplitude (bound) is a = 6.65 ± 0.04 fm, σ(free) = 4.84 ± 0.04 b (1983KO17). Parameters of observed resonances are shown in Table 12.4 (in PDF or PS). See also (1981MUZQ). Differential cross sections have been studied for E_n = 75 keV to 4.5 MeV [see (1980AJ01)] and for 2.6 to 8.0 MeV (1980WH01; n₀) and 4.86 to 7.55 MeV (1983KO03; n₀, n₁ and, at higher energies, n₂, n₃). Total cross-section measurements have been reported for E_n = 0.3 to 18.0 MeV [see (1968AJ02, 1980AJ01)] and 4.86 to 7.55 MeV (1983KO03). The polarization has been measured at E_n = 75 keV to 2.2 MeV: see (1980AJ01). See also (1983GO1H).

Results from the most recent R-matrix analysis are displayed in Table 12.4 (in PDF or PS) (1983KO03). See also (1980WH01, 1983DA22). For a discussion of the earlier work see (1980AJ01). See also (1979GLZV, 1980HA35; theor.).

12. (a) 11B(n, p)11Be	Qm = -10.726	Eb = 3.369
(b) 11B(n, d)10Be	Qm = -9.0042
(c) 11B(n, t)9Be	Qm = -9.5589
(d) 11B(n, α)8Li	Qm = -6.632

The cross section for reaction (a) has been measured for E_n = 14.7 to 16.9 MeV and that for reaction (b) has been investigated for E_n = 12.6 to 20.0 MeV and at 25 and 38 MeV: see (1975AJ02). A recent study of reaction (d) at E_n = 14.4 MeV is reported by (1979AN18). See also (1980AJ01).

13. 11B(p, π+)12B

Qm = -136.980

(1979MA38) have measured the cross section for π⁺ production near threshold. At E_p = 200 MeV the population of ¹²B*(0, 0.95, 1.67, 2.62, 3.39, 3.76, 4.30 + 4.52, 5.00, 5.61) is reported by (1980SO05). See also the "GENERAL" section here.

14. 11B(d, p)12B

Qm = 1.145

Observed proton groups and γ-rays are displayed in Table 12.5 (in PDF or PS). The J^π assignments for ¹²B*(0.95, 1.67) are derived as follows [see (1968AJ02) for a listing of earlier references]: 0.95 MeV: l_n = 1 leads to J^π = 0⁺, 1⁺, 2⁺ or 3⁺. The γ-radiation is anisotropic and therefore J ≠ 0. τ_m is too short for pure E2 and hence J ≠ 3, which is conformed by studies of the polarization of γ₁. The results are consistent with J^π = 1⁺ and 2⁺. The latter is fixed by γγ correlations in the cascade 1.67 → 0.95 → g.s. The mixing ratio δ = -0.08 ± 0.06. 1.67 MeV: l_n = 0 and therefore J^π = 1^- or 2^-. The state decays primarily to ¹²B_g.s.. Gamma-gamma correlations lead to J^π = 2^-. An assignment of 1^- to ¹²B*(2.62) is made in a similar manner.

See Table 12.12 (in PDF or PS) in (1980AJ01) for a comparison of the properties of the first seven T = 1 states in ¹²B and in ¹²C. See also (1981HU1G) and (1982GO05; theor.).

15. 12Be(β-)12B

Qm = 11.708

See ¹²Be.

16. (a) 12C(γ, π+)12B	Qm = -152.937
(b) 12C(e, eπ+)12B	Qm = -152.937
(c) 12C(π-, γ)12B	Qm = 126.198

Using monoenergetic photons with E_γ = 210 to 381 MeV (1982AR06) have measured the total cross section for π⁺ emission and the spectra of the positive pions. The latter show the influence of quasi-free pion production and FSI processes. At E_e = 195 and 200 MeV the π⁺ energy distributions show contributions from ¹²B*(0, 0.95, ≈ 4.5, 7.0) (1980MI08, 1980SH22, 1983SH1W). The 2^- and 4^- states at E_x ≈ 4.5 MeV are compared with their isobaric analogs in ¹²C at E_x ≈ 19.5 MeV (1980MI08). At E_e = 400 MeV (1983SC03, 1983SC11) have studied π⁺ with E_π = 32 MeV: double differential cross sections are obtained for the transitions to ¹²B*(0, 0.95, 1.67) and single differential cross sections to ¹²B*(0, 0.95). (1983SC03) found that the cross section (at θ = 54°) is the same whether virtual or real photons are used in producing the pions.

For the earlier work see (1980AJ01). See also (1979TR1B), (1979CH31, 1980NA11, 1981SI09; theor.) and the "GENERAL" section here.

17. 12C(μ-, ν)12B

Qm = 92.290

Observations of γ-transitions have led to the determination of the capture rates to ¹²B*(0, 0.95, 1.67, 2.62) [J^π = 1⁺, 2⁺, 2^-, 1^-] (1981GI08, 1981RO15). The ratio of the polarization of ¹²B_g.s., P_av, and of the longitudinal polarization, P_L, has been determined by (1981RO05, 1981RO15, 1982RO13): this ratio leads to a neutrino helicity, h_ν = -1.08 ± 0.11, in agreement with the partial conservation of axial-vector current (PCAC) hypothesis. See also the "GENERAL" section here. For the earlier work see (1980AJ01).

18. 12C(n, p)12B

Qm = -12.587

At E_n = 59.6 MeV (1982BR04) have determined the angular distribution of the p₀ group. Broad (unresolved) structures are also observed with E_x < 10 MeV (1984BR03). The use of this reaction for the production of polarized ¹²B nuclei is discussed by (1982DE16). For the earlier work see (1980AJ01).

19. 12C(d, 2p)12B

Qm = -14.812

Angular distributions are reported at E_d = 55 MeV to ¹²B*(0, 0.95, 4.5). ¹²B*(1.67, 5.6 and 8.0) are also populated (1979ST15). At E_d = 99.2 MeV σ(θ) at forward angles have been measured for the transitions to ¹²B*(0, 4.5). The differential cross sections are nearly the same for the two groups (1982BE33).

20. 12C(7Li, 7Be)12B

Qm = -14.231

At E(⁷Li) = 78 MeV the population of ¹²B*(0, 0.95, 4.52) is reported by (1984GA1N). In the earlier work of (1973BA34; E(⁷Li) = 52 MeV) ¹²B*(1.71, 2.70, 2.87) were also observed. See also (1982AL1G).

21. 12C(14N, 14O)12B

Qm = -18.512

See (1979NA1G).

22. 13C(γ, p)12B

Qm = -17.533

See (1983ZU02). See also ¹³C in (1981AJ01, 1986AJ01).

23. 13C(d, 3He)12B

Qm = -12.040

Angular distributions have been measured for the transitions to ¹²B*(0, 0.95) at E_d = 24.1 to 29 and at 52 MeV. Distributions to ¹²B*(2.72, 3.76, 5.00) have been reported at E_d = 52 MeV: see (1980AJ01). The spectroscopic factors for ¹²B*(0, 0.95) are S = 1.1 ± 0.2 and 2.0 ± 0.5. C²S = 1.09 [assuming 1p_3/2], 2.17, 0.14, 0.07, 0.22 [assuming 1p_1/2] for ¹²B*(0, 0.95, 2.72, 3.76, 5.00) [from measurements at E_d = 52 MeV]. See (1980AJ01) for references. For a discussion of analog states of ¹²B and ¹²C see reaction 67 in ¹²C. See also ¹⁵N in (1981AJ01), (1979SHZH, 1983AD1B) and (1980LE14; theor.).

24. 14C(p, 3He)12B

Qm = -17.992

At E_p = 54 MeV, in addition to transitions to ¹²B*(0, 0.95, 5.61), the population of T = 2 states at E_x = 12.72 ± 0.07 and 14.82 ± 0.10 MeV is reported. The angular distribution of ³He ions to ¹²B*(12.75) is fitted by L = 0; that to ¹²B*(12.82) is rather featureless [its T = 2 characater is assigned from the energies of the analog states]: both states have Γ_c.m. ≲ 200 keV (1976AS01). See also reaction 72 in ¹²C and (1983AR1K).

25. 14N(12C, 14O)12B

Qm = -18.510

See (1980AJ01).

26. 18O(d, 8Be)12B

Qm = -5.957

See (1984NE1A).