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14B (1976AJ04)
(See Energy Level Diagrams for 14B)
GENERAL: See also (1970AJ04) and Table 14.1 [Table of Energy Levels] (in PDF or PS).
See (1970AR1D, 1970AR27, 1971AR02), (1973KO1D, 1973TO16) and (1972TH13, 1973WI15, 1974TH01, 1975JE02, 1975BE31, 1975MI12; theor.).
Mass of 14B: From the Q-value of the 14C(7Li, 7Be)14B reaction the atomic mass excess of 14B is 23.657 ± 0.030 MeV. 14B is then stable with respect to breakup into 13B + n and 12B + 2n by 0.98 and 5.86 MeV, respectively (1973BA34). The lowest T = 2 states in 14C, 14N and 14O are estimated to lie at Ex = 22.5, 24.8 and 22.5 MeV. These states would then be stable against allowed neutron decay by ≈ 0.7 MeV and unstable to proton decay by < 3.0 MeV (1973BA34).
| 1. 14B(β-)14C | Qm = 20.64 |
14B has a half-life of 16.1 ± 1.2 msec. The β-decay is primarily to 14C*(6.09) [Jπ = 1-] and (6.73) [Jπ = 3-]: see Table 14.2 (in PDF or PS). The measured γ-ray intensity ratios are I6.09/I6.73/I7.34 = 100/(10.0 ± 2.0) /< 2.2. The nature of the decay fixes the Jπ of 14B to be 2- (1974AL11). See also (1975MI12; theor.).
| 2. 10Be(6Li, 2p)14B | Qm = -11.54 |
14B has been populated in this reaction at E(6Li) = 31 MeV (1974AL11).
| 3. 10Be(9Be, αp)14B | Qm = -9.41 |
See (1974AL11).
| 4. 14C(7Li, 7Be)14B | Qm = -21.50 |
| Q0 = -21.499 ± 0.030 (1973BA34). |
14B states with 0 < Ex < 3 MeV have been populated in this reaction at E(7Li) = 52 MeV: see Table 14.1 (in PDF or PS). Similarities in the relative intensities of 14B*(0, 0.74, 1.38, 1.82, 2.08) and of 12B*(1.67, 2.62, 3.39, 4.37, 4.52) [populated in 12C(7Li, 7Be)12B], and the similarity in the ΔEx of these 12B states with the Ex of the 14B states suggest that they have the same Jπ. The differential cross section for producing 14Bg.s. at θ = 15° is ≈ 4 μb/sr (1973BA34).