
^{8}Li (1988AJ01)(See Energy Level Diagrams for ^{8}Li) GENERAL: See also (1984AJ01) and Table 8.2 [Table of Energy Levels] (in PDF or PS) here. Nuclear models: (1983KU17, 1983SH38, 1984MO1H, 1984REZZ, 1984VA06, 1988WO04). Special states: (1982PO12, 1983KU17, 1984REZZ, 1984VA06, 1986XU02). Electromagnetic transitions: (1983KU17). Astrophysics: (1987MA2C). Complex reactions involving ^{8}Li: (1983FR1A, 1983GU1A, 1983OL1A, 1983WI1A, 1984GR08, 1984HI1A, 1984LA27, 1985JA18, 1985MA02, 1985MA13, 1985MO17, 1985MO24, 1986AV1B, 1986CS1A, 1986GO1G, 1986HA1B, 1986MA19, 1986NAZV, 1986SA30, 1986SIZS, 1986WE1C, 1986XU02, 1987BA38, 1987BE58, 1987BL13, 1987CH26, 1987DE37, 1987GR11, 1987JA06, 1987LY04, 1987TAZU, 1987WA09, 1988AU1A, 1988BL09, 1988CA06, 1988KI05, 1988LI1A, 1988RU01, 1988ST06, 1988TA1A). Polarization of ^{8}Li: (1984KO25, 1986HA1P, 1986NO1C, 1986NO1D, 1987NO04). Applications: (1985HA40, 1986NO1C, 1987NO04). Reactions involving pions and other mesons: (1983HA45, 1986CE04, 1986GO1G). Hypernuclei: (1982KA1D, 1982MO1B, 1983MO1C, 1983SH1E, 1984AS1D, 1984CH1G, 1984MI1C, 1984MI1E, 1984SH1J, 1984ZH1B, 1985MO1F, 1986AN1R, 1986DA1B, 1986YA1F, 1987MI38, 1987PO1H, 1987YA1M, 1988TA29). Other topics: (1985AN28). Ground state of ^{8}Li: (1983ANZQ, 1985AN28, 1985SA32, 1986GL1A, 1987AR22, 1987HA30, 1987VA26, 1988JO1C, 1988POZS, 1988VA03, 1988WO04).
μ = +1.65335 ± 0.00035 nm: see (1978LEZA) Q = 24 ± 2 mb: see (1979AJ01). The interaction nuclear radius of ^{8}Li is 2.36 ± 0.02 fm (1985TA18) [see also for derived nuclear matter, charge and neutron matter r.m.s. radii].
The β^{} decay is to the broad 2^{+} firstexcited state of ^{8}Be, which then breaks up into 2α [see reaction 24 in ^{8}Be]. The halflife is 838 ± 6 msec [see (1984AJ01)]; log ft = 5.4 (1986WA01).
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) are 35 ± 10 and 35 ± 15 keV, respectively. J for the latter is ≥ 4: see (1979AJ01).
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 ^{8}Li*(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 ^{8}Li*(2.26) → ^{7}Li_{g.s.} + n in the interaction of 35 MeV/A ^{14}N ions on Ag is reported by (1987BL13).
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 n_{0}, n_{0 + 1} and n_{2} at E_{n} = 6.82, 8.90 and 9.80 MeV. (1987SC08; n_{2} at the two higher energies). A pronounced resonance is observed at E_{n} = 254 keV with J^{π} = 3^{+}, formed by pwaves: 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) [^{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: see (1974AJ01, 1984AJ01). A multilevel, multichannel Rmatrix calculation is reported by (1987KN04). This analysis leads to predictions for the cross section for elastic scattering, for (n, n') to ^{7}Li*(0.48, 4.68, 6.68) and for triton production. A number of additional (broad) states of ^{8}Li, 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.).
The excitation 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. 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 n_{0} + n_{1}) and n_{2} have been reported at E_{n} = 8.9 MeV (1984FE1A; prelim.). For Rmatrix 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 ^{4}H (1986MI11). The halflife of ^{3}H 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).
See (1985CH37, 1986CH24). See also (1984SH1B, 1986BOZG, 1988MA1H).
Angular distributions and analyzing powers for the transitions to ^{8}Li*(0, 0.98, 2.26) have been studied at E_{p} = 200.4 MeV. [The (p, π^{}) reaction to the analog states in ^{8}B 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 ^{8}Li. Those to ^{8}Li*(0, 2.26) have differential cross sections which exhibit a maximum near the invariant mass of the Δ_{1232} and A_{y} which are similar to each other and to those of the pol. pp → dπ^{+} reaction. ^{8}Li*(6.53) is clearly populated (1987HU12).
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). Angular distributions have also been measured at several energies in the range of E_{d} = 0.49 → 3.44 MeV (p_{0}) and 0.95 to 2.94 MeV (p_{1}). The lifetime of ^{8}Li*(0.98) is 10.1 ± 4.5 fsec: see (1979AJ01). See also (1985FI1D; astrophysics).
See (1984KO25).
See ^{8}He.
For reaction (a) see (1984AJ01) and (1985KI1A). The summed proton spectrum (reaction (b)) 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: 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).
Angular distributions have been reported for the ^{3}He ions to ^{8}Li*(0, 0.98, 2.26, 6.53) at E_{d} = 28 MeV [C^{2}S(abs.) = 1.63, 0.61, 0.48, 0.092] and 52 MeV. The distributions to ^{8}Li*(6.53)[Γ < 100 keV] are featureless: see (1979AJ01).
At E_{t} = 12.98 MeV, angular distributions of the αparticles to ^{8}Li*(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 C^{2}S have been derived (1988LI27). At E_{t} = 17 MeV, σ(θ) and A_{y} measurements, analyzed by CCBA, lead to J^{π} = 4^{+} for ^{8}Li*(6.53): see (1984AJ01). For ^{8}Li*(0.98), τ_{m} = 14 ± 5 fsec, E_{x} = 980.80 ± 0.10 keV: see (1974AJ01).
See (1984KO25).
See (1986BE1Q).
At E_{p} = 45 MeV, ^{3}He 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 (^{8}Be*(27.49)), measured in the analog reaction [^{10}Be(p, t)^{8}Be] are very similar. They are both consistent with L = 0 using a DWBA (LZR) analysis: see (1979AJ01).
Angular distributions of the α_{0} and α_{1} groups have been measured at E_{n} = 14.1 and 14.4 MeV: see (1974AJ01, 1984AJ01).
At E(^{7}Li) = 34 MeV angular distributions have been studied involving ^{8}Li*(0, 0.98) and ^{10}B_{g.s.} (1987CO16).
See (1984NE1A).
