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## 6Be (1966LA04)

(See Energy Level Diagrams for 6Be)

See also Table 6.9 [Table of Energy Levels] (in PDF or PS).

Mass of 6Be: From the Q-values of the 6Li(p, n)6Be reaction (Q0 = -5.069 ± 0.010 MeV) and the 6Li(3He, t)6Be reaction (Q0 = -4.306 ± 0.006 MeV), we adopt 6Be - 6Li = 4.2872 ± 0.005 MeV. The mass excess of 6Be is then 18.376 ± 0.005 MeV, based on 12C ≡ 0.

 1. (a) 3He(3He, 2p)4He Qm = 12.860 Eb = 11.487 (b) 3He(3He, p)5Li Qm = 10.895 (c) 3He(3He, 3He)3He

The total cross section for proton production shows a monotonic increase for E(3He) = 100 to 800 keV (1954GO18). The zero-energy cross section factor S0 ≈ 1100 keV · b (1964PA1A). The elastic yield (reaction (c)) does not show any structure for E(3He) = 3 to 12 MeV: the yields at θ = 31°, 55°, 70° and 90° all decrease with increasing energy in a smooth fashion. The angular distributions at E(3He) = 3.0, 5.9, 7.9, 9.9 and 11.9 MeV disagree with the theoretical predictions based on the resonating group structure method (1963TO03). The 90° and 45° cross sections continue to decrease smoothly up to E(3He) = 18 MeV, implying that an odd-parity partial wave (probably l = 3) is beginning to contribute strongly to the cross section in a region corresponding to 6Be* (Ex > 18 MeV) ((1965BA2B) and private communication). The 65° differential cross section increases by a factor of 2.6 between E(3He) = 12 and 18 MeV (1965BA2B). This sharp upward trend is continued to E(3He) = 25 MeV (1960GA1C). Elastic σ(θ) have also been obtained at E(3He) = 12, 16, 19, 22 and 25 MeV (1965LE02), 29 MeV (1960BR19) and 30 MeV (1960MC1E). See also (1960BR27, 1964AR08, 1965BA1E, 1965TO01).

 2. 4He(3He, n)6Be Qm = -9.091

At E(3He) = 24.2 ± 0.3 MeV, two groups are reported corresponding to the ground state of 6Be and to an excited state at ≈ 1.5 MeV (1964BR13).

 3. 6Li(p, n)6Be Qm = -5.070 Qm = -5.2 ± 0.2 MeV (1957BO1F); Qm = -5.05 ± 0.2 MeV (1959AJ81); Qm = -5.05 ± 0.05 MeV (1964BA16); Qm = -5.08 ± 0.04 MeV (1963GU07); Qm = -5.074 ± 0.013 MeV (1964HOZZ); Qm = -5.061 ± 0.017 MeV (1963FR1E).

At Ep = 9 (1957BO1F), 10 (1963GU07) and 10.5 MeV (1959AJ81), the ground-state neutron group is observed: Γ < 300 keV (1957BO1F), ≲ 150 keV (1959AJ81), 140 ± 40 keV (1963GU07). The ground-state neutron threshold function indicates participation of both s- and p-wave neutrons (1964HOZZ). The ground-state width is 126 ± 15 keV (1963FR1E), 95 ± 28 keV (1964HOZZ). (1959AJ81) report evidence for an excited state at Ex = 1.5 ± 0.2 MeV, Γ < 100 keV. However (1964HOZZ) does not observe any but the ground-state threshold up to Ex ≈ 3.8 MeV.

 4. 6Li(3He, t)6Be Qm = -4.306

At E(3He) = 12 MeV (θ = 2°, 10°), a triton group is observed corresponding to the ground state of 6Be (Γ = 89 ± 6 keV, Q0 = -4.306 ± 0.006 MeV). No other states of 6Be are seen with Γ < 1 MeV up to Ex = 2.8 MeV (1964WH06).