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GENERAL: See also Table 8.1 [Table of Energy Levels] (in PDF or PS).

Theory: See (LA55A, KU56, FR57, KU57).

1. 8Li(β-)8Be

Qm = 16.001

The weighted mean of half-lives reported in (55AJ61) is 0.848 ± 0.004 sec. A value of 0.873 ± 0.013 sec is given by (VE58A). See also (IM58). The decay is complex: see ⁸Be.

2. 6Li(t, p)8Li	Qm = 0.803
	Q0 = 0.790 ± 0.011 (AL54E).

The ground state reaction has been observed by (MO52, PE52, AL54E, CU55B). (CU55B) also reports one event corresponding to the transition to an excited state at 0.7 ± 0.2 MeV.

3. 7Li(n, γ)8Li

Qm = 2.035

The thermal capture cross section is 33 ± 5 mb (HU47A), 42 ± 10 mb (KO56E). At E_n = 275 keV, neutron capture is not observed: σ < 0.25 mb (KO56E). Polarization of ⁸Li produced by polarized thermal neutrons has been detected by (BU57). See also (KU57, IM58, SH58).

4. 7Li(n, n)7Li

Eb = 2.035

Cross sections for Li metal and for ⁷Li are reported in (HU58: see also (GO56M, KA57B, BR58H)). The thermal cross section is 1.07 ± 0.04 b (C. Hibdon: see (HU55C, TH56)).

A pronounced resonance occurs at E_n = 258 keV (see Table 8.2 (in PDF or PS)). Total cross sections and angular distributions establish that the state has J = 3⁺, formed by p-waves (WI56A). A further, broad peak centering at E_n ~ 5 MeV may indicate a broad level of ⁸Li at ~ 6.5 MeV (HU58: see also (GO56M)).

Data on coherent scattering and total cross section for zero-energy neutrons permit two solutions for the two s-wave scattering lengths corresponding to anti-parallel (J = 1^-) and parallel (J = 2^-) interactions; for the first solution, the interaction is essentially pure J = 1^-, for the other, pure J = 2^-. Measurement of the interference between the s-wave background and the p-wave (channel spin 2) resonance indicate that the second solution is the correct one, and it is concluded that the splitting between parallel and anti-parallel interactions is about 1.5 MeV (TH56). (WI56A) find, on the other hand, that the observed asymmetries in the angular distributions indicate a nearly statistical (5/3) mixture of J = 1^- and 2^- background. Use of scattering in ⁷Li as a polarization analyzer is discussed by (WI56B).

See also (BE56C, KH57A).

5. 7Li(n, n')7Li*

Eb = 2.035

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. The rise above threshold indicates the existence of a J = 1^- level, which may be identified with the 1.35-MeV resonance (if a strong d-wave contribution is included). On the other hand, the latter resonance appears to be better described as a J = 1⁺ level, formed by p-waves. Under this assumption, E_r(lab) = 1.45 MeV, Γ = 1.14 MeV, with the sum of reduced widths θ²_in + θ²_out ~ 0.5 x (3(h-bar)²/2MR²). The ratio θ²_in/θ²_out = 0.1 to 0.4 or 1.0 to 3.0 (FR55A).

6. 7Li(n, p)7He

Qm = -14

Eb = 2.035

Not observed: see ⁷He.

7. 7Li(n, d)6He

Qm = -7.779

Eb = 2.035

At E_n = 14 MeV, the cross section is 9.8 ± 1.1 mb (BA53). See also (FR54B).

8. (a) 7Li(n, t)5He	Qm = -3.423	Eb = 2.035
(b) 7Li(n, t)4He + n	Qm = -2.466

The cross section for reaction (a) is 55 ± 8 mb at E_n = 14 MeV (FR54B). See also (MA54F) and (BA54).

9. 7Li(d, p)8Li	Qm = -0.192
	Q0 = -0.183 ± 0.02 (KH55).

Three proton groups are observed, corresponding to the ground state and to levels at 0.974 ± 0.015 (LE55), 0.977 ± 0.02 MeV (KH55, KH55A) and 2.28 MeV (LE55). A search for further levels in the range E_x = 2.28 to 8 MeV revealed no levels with Γ < 80 keV (HA58A). At E_d = 14 MeV, the angular distributions of the protons, analyzed by stripping theory, indicate l_n = 1 and therefore even parity, J < / = 3, for the ground state and the 0.98-MeV level (LE55). On the assumption that J = 2⁺ and 1⁺ for the ground state and 0.98-MeV level, respectively, (FR57) calculate θ² = 0.054 and 0.028 from the data of (LE55). These two levels are presumed to arise from a ³³P term, with a third component of J = 0⁺ expected at higher energy (FR57). See also (GI55).

10. 7Li(t, d)8Li

Qm = -4.224

Not observed.

11. 7Li(α, 3He)8Li

Qm = -18.543

Not observed.

12. 9Be(γ, p)8Li

Qm = -16.885

See ⁹Be and (CH58C).

13. 9Be(n, d)8Li

Qm = -14.658

Not observed.

14. 9Be(p, 2p)8Li

Qm = -16.885

Production of ⁸Li at E_p = 20 MeV is reported by (LE56G). At E_p = 185 MeV, the summed proton spectrum shows two peaks, corresponding to pickup of protons with binding energies of ~ 18 and ~ 26 MeV, respectively. There is some indication of α-particle structure (MA58H, TY58B).

15. 9Be(d, 3He)8Li

Qm = -11.409

See (WI54F).

16. 9Be(t, α)8Li

Qm = 2.928

Not observed.

17. 10B(n, 3He)8Li

Qm = -15.771

Not observed.

18. 11B(n, α)8Li

Qm = -6.636

See ¹²B.