
^{8}Li (1979AJ01)(See Energy Level Diagrams for ^{8}Li) 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).
μ = +1.65335 ± 0.00035 nm (1973HA12). See also (1974AJ01);
The βdecay leads mainly to ^{8}Be*(2.9): see ^{8}Be. The adopted halflife [see (1974AJ01)] = 842 ± 6 msec, log ft = 5.61 (B. Zimmerman, private communication). The distribution of recoil momenta indicates J^{π} = 2^{+} for ^{8}Li_{g.s.}. The coefficient for the angular correlation between β^{}, ν_{e}bar and αparticles, 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 βdecay in polarized ^{8}Li nuclei and have determined the quadrupole moment for ^{8}Li_{g.s.}: see the "GENERAL" section here. See also reaction 28 in ^{8}Be.
Angular distributions have been obtained at E_{t} = 23 MeV for the proton groups to ^{8}Li*(0, 0.98, 2.26, 6.54 ± 0.03); Γ_{c.m.} for ^{8}Li*(2.26, 6.54) = 35 ± 10 and 35 ± 15 keV, respectively; J for the latter is ≥ 4 (1978AJ02).
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 the interval. The cross section shows the resonance corresponding to ^{8}Li*(2.26): Γ_{γ} = 0.07 ± 0.03 eV (1959IM04); E_{res} = 254 ± 3 keV, Γ_{n} = 31 ± 7 keV (1971AL09): see Table 8.2 (in PDF or PS). For unpublished data see (1974AJ01). See also (1976GAYV).
The thermal cross section is 1.07 ± 0.04 b (1960HU08); the coherent scattering length (thermal, bound) is 2.1 ± 0.1 fm (see (1973MU14)). See also (1974RO20). Total crosssection measurements have been reported for E_{n} = 5 eV to 30 MeV [see (1974AJ01, 1976GAYV)] and by (1976KN1D, 1976LA1C; E_{n} = 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 ^{7}Li. A pronounced resonance is observed at E_{n} = 261 keV with J^{π} = 3^{+}, formed by pwaves (Table 8.2 (in PDF or PS)) (1970ME1C). 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 (1964LA19). Broad peaks are reported at E_{n} = 4.6 and 5.8 MeV (± 0.1 MeV) [^{8}Li*(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 [^{8}Li*(6.5)] with Γ « 80 keV and of a weak, broad peak at E_{n} = 3.7 MeV (1971FO1P, 1971FO24) [and see (1974AJ01)]. See also (1977ST24, 1978ST20; theor.).
The exciation function for 0.48 MeV γrays shows an abrupt rise from threshold (indicating swave 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 (1955FR10). At higher energies 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. The two resonances are interpreted as being due to states with J^{π} = 2^{+} or 3^{+} [^{8}Li*(5.4)] [see, however, (1978ST20)] and J^{π} = 3^{+} or 3^{} [^{8}Li*(6.4)] [(1972PR03): Γ_{λ}, γ^{2}_{λ} and θ^{2}_{λ} are listed for these two states under various assumptions]. (1977BA62) predicts a 2^{} state at E_{x} = 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 γrays has been measured at 125° for E_{n} = 0.4 to 20 MeV: it shows the structures described above followed by a decrease in the cross section from E_{n} = 6 to 20 MeV with some evidence of structures at E_{n} = 6.8 and 8 MeV (1977DI11). Crosssection measurements have also been reported for E_{n} = 0.57 to 4.0 MeV (1976SM08), 4.0 to 7.5 MeV (1977KN1B) and 7 to 13 MeV (1976BI1B; n_{0+1}, n_{2}). See also (1976MI1C, 1978LI1C) and the review in (1976GAYV). For applications see (1974ST1D).
See (1977RI07) and ^{7}He. See also (1976SL2A).
See ^{6}He. See also (1976SL2A).
The cross section rises to 450 mb at E_{n} ≈ 8 MeV and thereafter decreases slowly to 300 mb at E_{n} = 15 MeV (1976GAYV). See also (1975VO1C, 1978QA01), (1974ST1D; applied) and (1976SL2A).
Angular distributions of the p_{0} and p_{1} groups [l_{n} = 1] at E_{d} = 12 MeV have been analyzed by DWBA: S_{exp} = 0.87 and 0.48 respectively for ^{8}Li*(0, 0.98) [S_{exp}/S_{theor} = 0.84, 1.09] (1967SC29). Angular distributions have also been measured at several energies in the range E_{d} = 0.49 → 3.44 MeV (p_{0}) and 0.95 to 2.94 MeV (p_{1}) by (1975MC02). The first excited state decays by emitting a 980 ± 10 keV γray. The transition is M1 (1962CH14). The lifetime of ^{8}Li*(0.98) is 10.1 ± 4.5 fsec (1971TH02). See also (1975MI04, 1978HA1K), (1974AJ01, 1976HA1J) and (1974LO10, 1975KU27, 1976KU07; theor.).
See ^{8}He.
See ^{9}Be.
At E_{e} = 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 ^{9}Be and (1977BE1Q, 1977MO1F).
See ^{10}Be.
The population of ^{8}Li*(0.98) and its subsequent γdecay are reported by (1978MO01).
The summed proton spectrum at E_{p} = 156 MeV shows peaks corresponding to ^{8}Li(0) and ^{8}Li*(0.98 + 2.26) [unresolved]. In addition sstates [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 (1967RO06). See also ^{9}Be.
Angular distributions have been reported for the ^{3}He ions to ^{8}Li*(0, 0.98, 2.26, 6.53) at E_{d} = 27.97 MeV (1977OO01; C^{2}S(abs.) = 1.63, 0.61, 0.48, 0.092) and 52 MeV (1975SC41; S_{p3/2} = 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 ^{8}Li*(6.53) [Γ < 100 keV (1974DI1A, 1975DI1B)] are featureless (1975DI1B, 1975SC41, 1977OO01). See reaction 32 [^{9}Be(d, t)] in ^{8}Be (1977OO01). At E_{d} = 80 MeV, (1974DI1A, 1975DI1B; abstracts) report a broad peak at E_{x} ≈ 9 MeV corresponding to sshell pickup. See also (1975RO1E).
At E_{t} = 12.98 MeV, αparticle groups are observed to ^{8}Li*(0, 0.98, 2.26) and to a state at E_{x} = 6.530 ± 0.020 MeV with Γ_{c.m.} < 40 keV (1965WA12). For angular distributions to these four states, see (1968AJ01): the distribution of the αparticles to ^{8}Li*(6.53) is rather featureless and does not involve a forward maximum, suggesting l > 1. A large ltransfer is consistent with the narrow width of this unbound state (1968AJ01). See also (1974AJ01) for unpublished measurements and earlier work. The mean lifetime, τ_{m} = 14 ± 5 fsec for ^{8}Li*(0.98): E_{x} = 980.80 ± 0.10 keV (1972CO09). See also ^{12}B in (1975AJ02).
See (1974KE1C) and (1974AJ01).
At E_{p} = 45 MeV ^{3}He ions are observed to a state of 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 (^{8}Be*(27.49)), measured in the mirror reaction [^{10}Be(p, t)^{8}Be] 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).
See ^{12}B in (1975AJ02).
At E(^{6}Li) = 80 MeV, ^{8}Li*(0, 0.98, 2.26, 6.53) are populated (1976WE09, 1977WE1B).
See (1963NE07).
Angular distributions for the α_{0} and α_{1} groups have been measured at E_{n} = 14.1 MeV (1973BO26). See also ^{12}B in (1975AJ02) and (1977AN1C).
At E_{α} = 129 MeV, ^{8}B groups are observed to ^{8}Li*(0, 0.98, 2.26) (1968MC02).
See (1976BE1L).
At E(^{7}Li) = 34 MeV angular distributions have been measured for the transitions to ^{8}Li_{g.s.} + ^{12}C_{g.s.}, ^{8}Li*_{0.98} + ^{12}C_{g.s.}, ^{8}Li_{g.s.} + ^{12}C*_{4.4} and ^{8}Li*_{0.98} + ^{12}C*_{4.4} (1973SC26).
At E(^{3}He) = 76 MeV ^{8}Li*(0, 0.98) are populated (1976RO04).
See (1974AJ01).
See (1975BE38).
