A=8Li (1988AJ01)

The β^- decay is to the broad 2⁺ first-excited state of ⁸Be, which then breaks up into 2α [see reaction 24 in ⁸Be]. The half-life is 838 ± 6 msec [see (1984AJ01)]; log ft = 5.4 (1986WA01).

2. ⁶Li(t, p)⁸Li Q_m = 0.801

Angular distributions have been obtained at E_t = 23 MeV for the proton groups to ⁸Li*(0, 0.98, 2.26, 6.54 ± 0.03); Γ_c.m. for ⁸Li*(2.26, 6.54) are 35 ± 10 and 35 ± 15 keV, respectively. J for the latter is ≥ 4: see (1979AJ01).

3. ⁷Li(n, γ)⁸Li Q_m = 2.033

The cross section for capture radiation has been measured for E_n = 40 to 1000 keV; it decreases from 50 μb to 5 μb over that interval. The cross section shows the resonance corresponding to ⁸Li*(2.26): E_res = 254 ± 3 keV, Γ_n = 31 ± 7 keV, Γ_γ = 0.07 ± 0.03 eV: see Table 8.3 (in PDF or PS) and (1974AJ01). See also (1985SM1B), (1981MUZQ, 1984SH1N, 1986AB1E). The decay of ⁸Li*(2.26) → ⁷Li_g.s. + n in the interaction of 35 MeV/A ¹⁴N ions on Ag is reported by (1987BL13).

4. ⁷Li(n, n)⁷Li E_b = 2.033

The thermal cross section is 0.97 ± 0.04 b [see (1981MUZQ)], σ_free = 1.07 ± 0.03 b (1983KO17). The real coherent scattering length is - 2.22 ± 0.01 fm. The complex scattering lengths are b₊ = - 4.15 ± 0.06 fm and b_- = 1.00 ± 0.08 fm (1983KO17); see also (1979GL12). See (1984AJ01) for earlier references.

Total and elastic cross sections have been reported for E_n = 5 eV to 49.6 MeV: see (1974AJ01, 1979AJ01, 1984AJ01). Cross sections have also been reported for n₀, n_{0 + 1} and n₂ at E_n = 6.82, 8.90 and 9.80 MeV. (1987SC08; n₂ at the two higher energies).

A pronounced resonance is observed at E_n = 254 keV with J^π = 3⁺, formed by p-waves: see Table 8.3 (in PDF or PS). A good account of the polarization is given by the assumption of levels at E_n = 0.25 and 3.4 MeV, with J^π = 3⁺ and 2^-, together with a broad J^π = 3^- level at higher energy. Broad peaks are reported at E_n = 4.6 and 5.8 MeV (± 0.1 MeV) [⁸Li*(6.1, 7.1)] with Γ ≈ 1.0 and 0.4 MeV, respectively, and there is indication of a narrow peak at E_n = 5.1 MeV [⁸Li*(6.5)] with Γ ≪ 80 keV and of a weak, broad peak at E_n = 3.7 MeV: see (1974AJ01, 1984AJ01). A multi-level, multi-channel R-matrix calculation is reported by (1987KN04). This analysis leads to predictions for the cross section for elastic scattering, for (n, n') to ⁷Li*(0.48, 4.68, 6.68) and for triton production. A number of additional (broad) states of ⁸Li, unobserved directly in this and in other reactions, derive from this analysis (1987KN04). See also (1984FE1A, 1984MO1J), (1983DA22, 1983GO1H, 1984SH1N, 1984SH1B, 1986BOZG, 1987LE33, 1988MA1H) and (1983FA17, 1986BA09, 1986FIZX, 1987VE02; theor.).

5. (a) ⁷Li(n, n')⁷Li E_b = 2.033
(b) ⁷Li(n, n')³H + ⁴He Q_m = -2.4678

The excitation function for 0.48 MeV γ-rays shows an abrupt rise from threshold (indicating s-wave formation and emission) and a broad maximum (Γ ≈ 1 MeV) at E_n = 1.35 MeV. A good fit is obtained with either J^π = 1^- or 1⁺ (2⁺ not excluded), Γ_lab = 1.14 MeV. A prominent peak is observed at E_n = 3.8 MeV (Γ_lab = 0.75 MeV) and there is some indication of a broad resonance (Γ_lab = 1.30 MeV) at E_n = 5.0 MeV. At higher energies there is some evidence for structuree at E_n = 6.8 and 8 MeV followed by a decrease in the cross section to 20 MeV: see (1979AJ01, 1984AJ01). The total cross section for n₀ + n₁) and n₂ have been reported at E_n = 8.9 MeV (1984FE1A; prelim.). For R-matrix analyses see (1987KN04) in reaction 4 and (1984AJ01).

The cross section for reaction (b) rises from threshold to ≈ 360 mb at E_n ≈ 6 MeV and then decreases slowly to ≈ 250 mb at E_n ≈ 16 MeV: see (1985SW01, 1987QA01). Cross sections for tritium production have been reported recently from threshold to E_n = 16 MeV (1983LI1C; prelim.), 4.57 to 14.1 MeV (1985SW01), 7.9 to 10.5 MeV (1987QA01), 14.74 MeV (1984SMZX; prelim.) and at 14.94 MeV (1985GO18: 302 ± 18 mb). At E_n = 14.95 MeV the total α production cross section [which includes to (n, 2n d) process] is 336 ± 16 mb (1986KN06). Spectra at 14.6 MeV may indicate the involvement of states of ⁴H (1986MI11). The half-life of ³H has recently been measured to be 12.38 ± 0.03 mean solar years (1987OL04). See also (1987TI07).

See also (1986DE20, 1986DR10), (1984SH1N, 1985BO1D, 1986BOZG, 1986LI15) and (1986CH1S, 1986FA13, 1986GO1K, 1986IG1A, 1986KO32, 1986MA1R, 1986SE1D, 1986SH1T, 1986SH33, 1986TA1H, 1986VE1A, 1986YA1K, 1986YO1D; applications).

6. ⁷Li(n, 2n)⁶Li Q_m = -7.2501 E_b = 2.033

See (1985CH37, 1986CH24). See also (1984SH1B, 1986BOZG, 1988MA1H).

7. ⁷Li(p, π⁺)⁸Li Q_m = -138.318

Angular distributions and analyzing powers for the transitions to ⁸Li*(0, 0.98, 2.26) have been studied at E_p = 200.4 MeV. [The (p, π^-) reaction to the analog states in ⁸B is discussed there.] The (p, π⁺) cross sections are an order of magnitude greater than the (p, π^-) cross sections and show a much stronger angular dependence (1987CA06). Angular distributions and A_y have also been measured at E_p = 250, 354 and 489 MeV to the first three states of ⁸Li. Those to ⁸Li*(0, 2.26) have differential cross sections which exhibit a maximum near the invariant mass of the Δ₁₂₃₂ and A_y which are similar to each other and to those of the pol. pp → dπ⁺ reaction. ⁸Li*(6.53) is clearly populated (1987HU12).

8. ⁷Li(d, p)⁸Li Q_m = -0.192

Angular distributions of the p₀ and p₁ groups [l_n = 1] at E_d = 12 MeV have been analyzed by DWBA: S_exp = 0.87 and 0.48 respectively for ⁸Li*(0, 0.98). Angular distributions have also been measured at several energies in the range of E_d = 0.49 → 3.44 MeV (p₀) and 0.95 to 2.94 MeV (p₁). The lifetime of ⁸Li*(0.98) is 10.1 ± 4.5 fsec: see (1979AJ01). See also (1985FI1D; astrophysics).

9. (a) ⁷Li(⁶Li, ⁵Li)⁸Li Q_m = -3.63
(b) ⁷Li(⁷Li, ⁶Li)⁸Li Q_m = -5.217

See (1984KO25).

10. ⁸He(β^-)⁸Li Q_m = 10.652

See ⁸He.

11. (a) ⁹Be(e, ep)⁸Li Q_m = -16.887
(b) ⁹Be(p, 2p)⁸Li Q_m = -16.887

For reaction (a) see (1984AJ01) and (1985KI1A). The summed proton spectrum (reaction (b)) at E_p = 156 MeV shows peaks corresponding to ⁸Li(0) and ⁸Li*(0.98 + 2.26) [unresolved]. In addition s-states [J^π = 1^-, 2^-] are suggested at E_x = 9 and 16 MeV, with Γ_c.m. ≈ 6 and 8 MeV; the latter may actually be due to continuum protons: see (1974AJ01). At E_p = 1 GeV the separation energy between 5 and 8 MeV broad 1p_3/2 and 1s_1/2 groups is reported to be 10.7 ± 0.5 MeV (1985BE30, 1985DO16). See also (1987GAZM).

12. ⁹Be(d, ³He)⁸Li Q_m = -11.393

Angular distributions have been reported for the ³He ions to ⁸Li*(0, 0.98, 2.26, 6.53) at E_d = 28 MeV [C²S(abs.) = 1.63, 0.61, 0.48, 0.092] and 52 MeV. The distributions to ⁸Li*(6.53)[Γ < 100 keV] are featureless: see (1979AJ01).

13. ⁹Be(t, α)⁸Li Q_m = 2.927

At E_t = 12.98 MeV, angular distributions of the α-particles to ⁸Li*(0, 0.98, 2.26, 6.53 ± 0.02 [Γ_c.m. < 40 keV]) have been measured: see (1974AJ01). At E_t = 17 MeV angular distributions to these four states have been analyzed by ZRDWBA and C²S have been derived (1988LI27). At E_t = 17 MeV, σ(θ) and A_y measurements, analyzed by CCBA, lead to J^π = 4⁺ for ⁸Li*(6.53): see (1984AJ01). For ⁸Li*(0.98), τ_m = 14 ± 5 fsec, E_x = 980.80 ± 0.10 keV: see (1974AJ01).

14. ⁹Be(⁷Li, ⁸Be)⁸Li Q_m = 0.367

See (1984KO25).

15. ⁹Be(¹¹B, ¹²C)⁸Li Q_m = -0.930

See (1986BE1Q).

16. ¹⁰Be(p, ³He)⁸Li Q_m = -15.981

At E_p = 45 MeV, ³He ions are observed to a state at E_x = 10.8222 ± 0.0055 MeV (Γ_c.m. < 12 keV): the angular distributions for the transition to this state, and to its analog (⁸Be*(27.49)), measured in the analog reaction [¹⁰Be(p, t)⁸Be] are very similar. They are both consistent with L = 0 using a DWBA (LZR) analysis: see (1979AJ01).

17. ¹¹B(n, α)⁸Li Q_m = -6.631

Angular distributions of the α₀ and α₁ groups have been measured at E_n = 14.1 and 14.4 MeV: see (1974AJ01, 1984AJ01).

18. ¹¹B(⁷Li, ¹⁰B)⁸Li Q_m = -9.421

At E(⁷Li) = 34 MeV angular distributions have been studied involving ⁸Li*(0, 0.98) and ¹⁰B_g.s. (1987CO16).

19. ¹³C(d, ⁷Be)⁸Li Q_m = -20.454

See (1984NE1A).