|
![]() |
![]() |
![]()
8B (84AJ01)(See Energy Level Diagrams for 8B) GENERAL: See also (79AJ01) and Table 8.11 [Table of Energy Levels] (in PDF or PS). Special states:(OK80). 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 (AL82H): see 8He, 10Be, as well as 11Be in (85AJ01).): (BO79GG, GR80D, MO81N). Astrophysical questions:(BA81OO, LI83). Reactions involving pions:(JU81A, NI81B, HA82W, HU83C). Hypernuclei:(WA81D). Other topics:(BE79A, AW82, NG82). Ground state of 8B:(NG82).
The β+ decay leads mainly to 8Be*(2.9). The mean half-lives listed in (74AJ01) 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 (79AJ01) and reaction 28 in 8Be. See also (RA78F), (DA79O, HA80Q, PE80K, BA81EE, BA81GG, BA81JJ, IT81, BA82B, CO82A, KL82B, TR83B; astrophsyics) and (DE79C, OK80, BA81OO, HO81C, IT82; theor.).
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 (AS82). See also (LE82I).
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 (74AJ01) and 9B.
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 (FI83A), appreciably lower than earlier results: see (79AJ01). Calulations by (BA80FF) 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 (ZI75C, BA80J, BA80FF, BA80NN, BA81II, BA82B, FI83A). The predicted 37Cl ν-capture rate is decreased to 5.3 SNU, a reduction of about 25% in the previous value (FI83A). See also (PE80K; astrophys.) and (WI81; theor.).
See (HA83B).
See (DO82).
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 (74AJ01).
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 (79AJ01).
See (79AJ01).
See (AL83C).
|
![]() |