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USNDP

8Li (1979AJ01)


(See Energy Level Diagrams for 8Li)

GENERAL: See also (1974AJ01) and Table 8.1 [Table of Energy Levels] (in PDF or PS).

Nuclear models: (1975KH1A, 1977ST24).

Special states: (1974IR04, 1976IR1B, 1978KH03).

Electromagnetic interactions: (1974KU06, 1976KU07).

Special reactions: (1973SI38, 1974BA70, 1974BA1N, 1974BO08, 1975FE1A, 1975ZE01, 1976BE67, 1976BO08, 1976BU16, 1977FE1B, 1977PR05, 1977ST1J, 1977YA1B, 1978DI04).

Muon and neutrino interactions: (1977BA1P).

Pion and kaon reactions (See also reaction 16.): (1968ZE1A, 1973AG05, 1973AG06, 1973CA1C, 1974BO1F, 1974ZI1A, 1975CO06, 1975KU1J, 1977JU1B, 1977MA1K, 1978MO01, 1978VE1B).

Astrophysical questions: (1977SC1D, 1977ST1J).

Other topics: (1974IR04, 1974SE1B, 1975KH1A, 1976IR1B, 1977TR07, 1978GA1C, 1978RO01).

Ground state properties: (1974KU06, 1974SHYR, 1975BE31, 1976FU06, 1977TR07, 1978RO01, 1978ZA1D).

J = 2 (1973NE10);

μ = +1.65335 ± 0.00035 nm (1973HA12). See also (1974AJ01);

Q= 24 ± 2 mb (1975MI04);
= 32 ± 6 mb (1974AC03);
= 32 mb (1977DU06).

1. 8Li(β-)8Be Qm = 16.005

The β-decay leads mainly to 8Be*(2.9): see 8Be. The adopted half-life [see (1974AJ01)] = 842 ± 6 msec, log ft = 5.61 (B. Zimmerman, private communication). The distribution of recoil momenta indicates Jπ = 2+ for 8Lig.s.. The coefficient for the angular correlation between β-, νe-bar and α-particles, b = -0.88 ± 0.08 (1965GR25), -1.01 ± 0.07 (1966EI02), in substantial agreement with b = -1, expected from axial vector coupling. (1975MI04) have looked at the symmetry of the β-decay in polarized 8Li nuclei and have determined the quadrupole moment for 8Lig.s.: see the "GENERAL" section here. See also reaction 28 in 8Be.

2. 6Li(t, p)8Li Qm = 0.801

Angular distributions have been obtained at Et = 23 MeV for the proton groups to 8Li*(0, 0.98, 2.26, 6.54 ± 0.03); Γc.m. for 8Li*(2.26, 6.54) = 35 ± 10 and 35 ± 15 keV, respectively; J for the latter is ≥ 4 (1978AJ02).

3. 7Li(n, γ)8Li Qm = 2.033

The cross section for capture radiation has been measured for En = 40 to 1000 keV: it decreases from 50 μb to 5 μb over the interval. The cross section shows the resonance corresponding to 8Li*(2.26): Γγ = 0.07 ± 0.03 eV (1959IM04); Eres = 254 ± 3 keV, Γn = 31 ± 7 keV (1971AL09): see Table 8.2 (in PDF or PS). For unpublished data see (1974AJ01). See also (1976GAYV).

4. 7Li(n, n)7Li Eb = 2.033

The thermal cross section is 1.07 ± 0.04 b (1960HU1A); the coherent scattering length (thermal, bound) is -2.1 ± 0.1 fm (see (1973MU14)). See also (1974RO20). Total cross-section measurements have been reported for En = 5 eV to 30 MeV [see (1974AJ01, 1976GAYV)] and by (1976KN1D, 1976LA1C; En = 4 to 7.5 MeV), (1974HY01; 14.1 MeV) and (1976MI1C; 14.6 MeV). For polarization measurements see (1966LA04, 1974AJ01). For angular distribution measurements see 7Li.

A pronounced resonance is observed at En = 261 keV with Jπ = 3+, formed by p-waves (Table 8.2 (in PDF or PS)) (1970ME1C). A good account of the polarization is given by the assumption of levels at En = 0.25 and 3.4 MeV, with Jπ = 3+ and 2-, together with a broad Jπ = 3- level at higher energy (1964LA19). Broad peaks are reported at En = 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 En = 5.1 MeV [8Li*(6.5)] with Γ « 80 keV and of a weak, broad peak at En = 3.7 MeV (1971FO1A) [and see (1974AJ01)]. See also (1977ST24, 1978ST20; theor.).

5. 7Li(n, n')7Li* Eb = 2.033

The exciation 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 En = 1.35 MeV. A good fit is obtained with either Jπ = 1- or 1+ (2+ not excluded), Γlab = 1.14 MeV (1955FR10). At higher energies a prominent peak is observed at En = 3.8 MeV (Γlab = 0.75 MeV) and there is some indication of a broad resonance (Γlab = 1.30 MeV) at En = 5.0 MeV. The two resonances are interpreted as being due to states with Jπ = 2+ or 3+ [8Li*(5.4)] [see, however, (1978ST20)] and Jπ = 3+ or 3- [8Li*(6.4)] [(1972PR03): Γλ, γ2λ and θ2λ are listed for these two states under various assumptions]. (1977BA62) predicts a 2- state at Ex = 2.74 MeV and 1- states at 3.52 and 5.4 MeV with Γ ≈ 1.8, 2.5 and 3.8 MeV. The excitation function for 0.48 MeV γ-rays has been measured at 125° for En = 0.4 to 20 MeV: it shows the structures described above followed by a decrease in the cross section from En = 6 to 20 MeV with some evidence of structures at En = 6.8 and 8 MeV (1977DI1A).

Cross-section measurements have also been reported for En = 0.57 to 4.0 MeV (1976SM1B), 4.0 to 7.5 MeV (1977KN1B) and 7 to 13 MeV (1976BI1B; n0+1, n2). See also (1976MI1C, 1978LI1C) and the review in (1976GAYV). For applications see (1974ST1D).

6. 7Li(n, 2n)6Li Qm = -7.251 Eb = 2.033

See (1974KO35, 1976GAYV).

7. 7Li(n, p)7He Qm = -10.40 Eb = 2.033

See (1977RI07) and 7He. See also (1976SL2A).

8. 7Li(n, d)6He Qm = -7.751 Eb = 2.033

See 6He. See also (1976SL2A).

9. 7Li(n, t)4He + n Qm = -2.467 Eb = 2.033

The cross section rises to 450 mb at En ≈ 8 MeV and thereafter decreases slowly to 300 mb at En = 15 MeV (1976GAYV). See also (1975VO1C, 1978QA01), (1974ST1D; applied) and (1976SL2A).

10. 7Li(d, p)8Li Qm = -0.192

Angular distributions of the p0 and p1 groups [ln = 1] at Ed = 12 MeV have been analyzed by DWBA: Sexp = 0.87 and 0.48 respectively for 8Li*(0, 0.98) [Sexp/Stheor = 0.84, 1.09] (1967SC29). Angular distributions have also been measured at several energies in the range Ed = 0.49 → 3.44 MeV (p0) and 0.95 to 2.94 MeV (p1) by (1975MC02). The first excited state decays by emitting a 980 ± 10 keV γ-ray. The transition is M1 (1962CH14). The lifetime of 8Li*(0.98) is 10.1 ± 4.5 fsec (1971TH02). See also (1975MI04, 1978HA1K), (1974AJ01, 1976HA1J) and (1974LO10, 1975KU27, 1976KU07; theor.).

11. 7Li(t, d)8Li Qm = -4.225

See 10Be in (1974AJ01).

12. 8He(β-)8Li Qm = 10.649

See 8He.

13. 9Be(γ, p)8Li Qm = -16.888

See 9Be.

14. 9Be(e, ep)8Li Qm = -16.888

At Ee = 801 MeV two groups are observed at Q = -28.7 ± 0.1 and -16.9 ± 0.1 MeV corresponding to the ejection of 1s and 1p protons (1974GO35). See also 9Be and (1977BE1Q, 1977MO1F).

15. 9Be(n, d)8Li Qm = -14.663

See 10Be.

16. 9Be(π+, π+p)8Li Qm = -16.888

The population of 8Li*(0.98) and its subsequent γ-decay are reported by (1978MO01).

17. 9Be(p, 2p)8Li Qm = -16.888

The summed proton spectrum at Ep = 156 MeV shows peaks corresponding to 8Li(0) and 8Li*(0.98 + 2.26) [unresolved]. In addition s-states [Jπ = 1-, 2-] are suggested at Ex = 9 and 16 MeV, with Γc.m. ≈ 6 and 8 MeV: the latter may actually be due to continuum protons (1967RO06). See also 9Be.

18. 9Be(d, 3He)8Li Qm = -11.394

Angular distributions have been reported for the 3He ions to 8Li*(0, 0.98, 2.26, 6.53) at Ed = 27.97 MeV (1977OO01; C2S(abs.) = 1.63, 0.61, 0.48, 0.092) and 52 MeV (1975SC41; Sp3/2 = 1.50, 0.63, 0.50 for the first three states, with the ground state value normalized to the predicted theoretical value). The distributions to 8Li*(6.53) [Γ < 100 keV (1974DI1A, 1975DI1B)] are featureless (1975DI1B, 1975SC41, 1977OO01). See reaction 32 [9Be(d, t)] in 8Be (1977OO01). At Ed = 80 MeV, (1974DI1A, 1975DI1B; abstracts) report a broad peak at Ex ≈ 9 MeV corresponding to s-shell pickup. See also (1975RO1E).

19. 9Be(t, α)8Li Qm = 2.926

At Et = 12.98 MeV, α-particle groups are observed to 8Li*(0, 0.98, 2.26) and to a state at Ex = 6.530 ± 0.020 MeV with Γc.m. < 40 keV (1965WA12). For angular distributions to these four states, see (1968AJ01): the distribution of the α-particles to 8Li*(6.53) is rather featureless and does not involve a forward maximum, suggesting l > 1. A large l-transfer is consistent with the narrow width of this unbound state (1968AJ01). See also (1974AJ01) for unpublished measurements and earlier work.

The mean lifetime, τm = 14 ± 5 fsec for 8Li*(0.98): Ex = 980.80 ± 0.10 keV (1972CO09). See also 12B in (1975AJ02).

20. 9Be(7Li, 8Be)8Li Qm = 0.368

See (1974KE1C) and (1974AJ01).

21. 10Be(p, 3He)8Li Qm = -15.982

At Ep = 45 MeV 3He ions are observed to a state of Ex = 10.8222 ± 0.0055 MeV (Γc.m. < 12 keV): the angular distributions for the transition to this state, and to its analog (8Be*(27.49)), measured in the mirror reaction [10Be(p, t)8Be] are very similar. They are both consistent with L = 0 using a DWBA (LZR) analysis (1975RO01). The particle decay of the T = 2 state has been studied by (1975ADZV; abstract).

22. 10Be(d, α)8Li Qm = 2.372

See 12B in (1975AJ02).

23. 10B(6Li, 8B)8Li Qm = -17.730

At E(6Li) = 80 MeV, 8Li*(0, 0.98, 2.26, 6.53) are populated (1976WE09, 1977WE1B).

24. 11B(γ, 3He)8Li Qm = -27.210

See (1963NE07).

25. 11B(n, α)8Li Qm = -6.633

Angular distributions for the α0 and α1 groups have been measured at En = 14.1 MeV (1973BO26). See also 12B in (1975AJ02) and (1977AN1C).

26. 12C(α, 8B)8Li Qm = -41.444

At Eα = 129 MeV, 8B groups are observed to 8Li*(0, 0.98, 2.26) (1968MC02).

27. 13C(3He, 8B)8Li Qm = -25.812

See (1976BE1L).

28. 13C(7Li, 12C)8Li Qm = -2.914

At E(7Li) = 34 MeV angular distributions have been measured for the transitions to 8Lig.s. + 12Cg.s., 8Li*0.98 + 12Cg.s., 8Lig.s. + 12C*4.4 and 8Li*0.98 + 12C*4.4 (1973SC26).

29. 14N(3He, 9C)8Li Qm = -32.064

At E(3He) = 76 MeV 8Li*(0, 0.98) are populated (1976RO04).

30. 18O(7Li, 17O)8Li Qm = -6.012

See (1974AJ01).

31. 24Mg(3He, 19Na)8Li Qm = -32.876

See (1975BE38).