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USNDP

8B (1984AJ01)


(See Energy Level Diagrams for 8B)

GENERAL: See also (1979AJ01) and Table 8.11 [Table of Energy Levels] (in PDF or PS).

Special states: (1980OK01).

Complex reactions involving 8B (The reactions 6Li(6Li, 4H)8B, 12C(6Li, 10Be)8B, 9Be(7Li, 8He)8B and 12C(7Li, 11Be)8B have been studied at E(6Li) = 72 MeV and E(7Li) = 83 MeV (1982AL08): see 8He, 10Be, as well as 11Be in (1985AJ01).): (1979BO22, 1980GR10, 1981MO20).

Astrophysical questions: (1981BA17, 1983LI01).

Reactions involving pions: ( 1981JU1A, 1981NI03, 1982HA57, 1983HU02).

Hypernuclei: (1981WA1J).

Other topics: (1979BE1H, 1982AW02, 1982NG01).

Ground state of 8B: (1982NG01).

μ = 1.0355 ± 0.0003 nm: see (1978LEZA).

1. 8B(β+)8Be Qm = 17.979

The β+ decay leads mainly to 8Be*(2.9). The mean half-lives listed in (1974AJ01) is 770 ± 3 msec; log ft = 5.64. There is also a branch to a 8Be* state at ≈ 16.6 MeV; log ft = 3.3. See also (1979AJ01) and reaction 28 in 8Be. See also (1978RA2A), (1979DA1D, 1980HA1V, 1980PE1N, 1981BA2B, 1981BA17, 1981BA2G, 1981IT1A, 1982BA80, 1982CO1D, 1982KL1C, 1983TR1F; astrophsyics) and (1979DE15, 1980OK01, 1981BA17, 1981HO06, 1982IT01; theor.).

2. 6Li(d, π-)8B Qm = -135.266

At Ed = 300 and 600 MeV 8B*(0, 0.78, 2.32) are populated: the cross sections are higher at the lower (subthreshold for pion production) energy (1982AS01). See also (1982LE1L).

3. 6Li(3He, n)8B Qm = -1.975

Angular distributions for the n0 group have been reported at E(3He) = 4.8 to 5.7 MeV: L = 0. Two measurements for the Ex of 8B*(0.78) are 767 ± 12 and 783 ± 10 keV [Γ = 40 ± 10 keV]: see (1974AJ01) and 9B.

4. 7Be(p, γ)8B Qm = 0.138

Absolute cross sections have been measured for Ep = 0.165 to 10.0 MeV. A resonance at Ep = 724 keV [8B*(0.771)] with Γlab ≈ 46 keV [σpeak = 2.20 ± 0.22 μb, Γγ = 50 ± 25 meV] is reported. The zero-energy cross-section factor S17(0) = 0.0216 ± 0.0025 keV · b (1983FI01), appreciably lower than earlier results: see (1979AJ01). Calulations by (1980BA35) had suggested that S(0) was in the range 0.014 to 0.022 keV · b. The astrophysical implications of this reaction are discussed by (1975ZI1A, 1980BA1P, 1980BA35, 1980BA2M, 1981BA2F, 1982BA80, 1983FI01). The predicted 37Cl ν-capture rate is decreased to 5.3 SNU, a reduction of about 25% in the previous value (1983FI01). See also (1980PE1N; astrophys.) and (1981WI04; theor.).

5. 7Be(d, n)8B Qm = -2.087

See (1983HA1W).

6. 10B(π+, d)8B Qm = 115.561

See (1982DO01).

7. 10B(p, t)8B Qm = -18.531

At Ep = 49.5 MeV angular distributions have been measured for the tritons to 8B*(0, 2.32): L = 2 and L = 0 + 2 leading to Jπ = 2+ and 3+, respectively. Measurements of Ex for 8B*(2.32) yield 2.29 ± 0.05 MeV, 2.34 ± 0.04 MeV [Γlab = 0.39 ± 0.04 MeV]. 8B*(0.78) is also observed: see (1974AJ01).

8. 11B(3He, 6He)8B Qm = -16.914

At E(3He) = 72 MeV the first T = 2 state is observed at Ex = 10.619 ± 0.009 MeV, Γ < 60 keV: dσ/dΩ(lab) = 190 nb/sr at θlab = 9°. No other states are observed within 2.4 MeV of this state. 8B*(0, 0.78, 2.32) have also been populated: see (1979AJ01).

9. 12C(3He, 7Li)8B Qm = -22.896

See (1979AJ01).

10. 14C(7Li, 13Be)8B Qm = -40.0

See (1983AL1N).