(See Energy Level Diagrams for 5Li)
Complex reactions involving 5Li: (1985PO18, 1985PO19, 1985WI1A, 1986BA2D, 1986CH10, 1986CS1A, 1986MA1V, 1986XU1B, 1987BL1K, 1987CH33, 1987CH32, 1987DE1O, 1987DU07, 1987FO08, 1987GA20, 1987GE1B, 1987HA45, 1987KI16, 1987LY04, 1987PE1B, 1988CEZZ, 1988SA09).
The ratio Γγ/Γpα has been determined for E(3He) = 63 to 150 keV [Ec.m. = 25 to 60 keV] by (1985CE13) by measuring simultaneously the γ-rays and the charged particles. Because of the large widths of the final states, γ0 and γ1 could not be resolved but the results are consistent with Ex = 3.0 ± 1.0 MeV for the excited state. Γγ0/Γpα is roughly constant for Ec.m. = 25 to 60 keV at (4.5 ± 1.2) × 10-5 and Γγ1/Γpα = (8 ± 3) × 10-5 at E(3He) = 150 keV (1985CE13). For applications see (1985CE13, 1985CE16).
Excitation curves and angular distributions have been measured for Ed = 0.2 to 5 MeV and E(3He) = 2 to 26 MeV. A broad maximum in the cross section is observed at Ed = 0.45 ± 0.04 MeV [5Li*(16.66)]. σγ0 = 21 ± 4 μb, Γγ0 = 5 ± 1 eV. The radiation at resonance is isotropic, consistent with s-wave capture. Study of γ0 and γ1 yields Γ = 2.6 ± 0.4 MeV for the ground-state width, and Ex = 7.5 ± 1.0 MeV, Γ = 6.6 ± 1.2 MeV for the 1/2- state: see (1974AJ01). An excess in the cross section at higher bombarding energies is interpreted as being due to a state at Ex ≈ 18 MeV: even parity is deduced from the relative intensity of γ0 and γ1. A broad peak is also observed at Ex ≈ 20.7 MeV in the γ0 cross section. The cross section for γ1 is ≈ 0. The observations are consistent with Jπ = 5/2+: angular distributions appear to require at least one other state with significant strength near 19 MeV: see (1974AJ01). For cross section and analyzing power measurements for Epol. d = 4 to 9 MeV see (1985RIZZ; prelim.).
Excitation functions and angular distributions have recently been measured for Ec.m. = 6.95 to 171.3 keV, and S(E) have been deduced: S(0) = 6.3 ± 0.6 MeV · b (1987KR18). See also (1984AJ01). Recently, S-factors have been obtained down to Ec.m. = 5.88 keV. The effect on S of electron screening at low energies has been studied by (1988EN03).
A pronounced resonance occurs at Ed = 430 keV, Γ ≈ 450 keV. The peak cross section is 695 ± 14 mb: see Table 5.2 (in PDF or PS) in (1979AJ01). Excitation functions for ground-state protons have also been reported for E(3He) = 0.39 to 2.15 MeV and 18.7 to 44.1 MeV and for Ed = 2.8 to 17.8 MeV [see (1974AJ01)]. Angular distributions hav been measured for Ed = 0.25 to 27 MeV and E(3He) = 18.7 to 44.1 MeV [see Table 5.6 (in PDF or PS) in (1974AJ01) and (1979AJ01)]. Resonance-like behavior has been suggested at Ex = 16.6, 17.5, 20.0, 20.9 and 22.4 MeV: see (1979AJ01).
Tensor analyzing power measurements are reported for Epol. d = 0.48 to 6.64 MeV (1980DR01). [See, however, (1980GR14) for a discussion of the (1980DR01) results and for a summary of T20(0°) for Epol. d = 0 to 40 MeV.] Measurements of angular distributions and analyzing powers at E(3He) = 27 and 33 MeV have suggested the presence of a broad resonance(s) at Ex ≈ 28 MeV. Vector and tensor analyzing powers have been studied at Epol. d = 1.0 to 13.0 MeV (1986BI1C, 1986BIZP; prelim.) and 18, 20 and 22 MeV (1986SA1L; prelim.). See also (1986RO1J) and Tables 5.6 (in PDF or PS) in (1974AJ01) and 5.4 (in PDF or PS) in (1979AJ01).
It is suggested that at low energies [Ed = 2.2 to 6 MeV] reaction (c) goes primarily via a Jπ = 3/2-, T = 1/2 state of 5Li located 0.8 ± 0.2 MeV above threshold [i.e., Ex = 18.9 ± 0.2 MeV]: see (1979AJ01). Recent studies of the breakup have been reported at Ed = 23.08 MeV (1986BR1J; reaction (c)) and 60 MeV (1985OK03; reaction (d)). For the earlier work see (1984AJ01).
See also (1983MA1E, 1984ALZU, 1984GA1C, 1984HA1J, 1984MU1C, 1984VL1A, 1984WI1C, 1985GU1F, 1985KU1B, 1986BI1E, 1986JA1E, 1986KA1L, 1986LO1B, 1986PO1F, 1986WI1B, 1986WI1E, 1987JO1A, 1987KA1O, 1987TE1D, 1988GU1G, 1988KU1E; applications), (1984YA1A, 1985CA41, 1986DE1K, 1987DO1H, 1987RO25; astrophysics), (1986VA1D, 1987GR08) and (1984DU10, 1984KR1B, 1986AB1C, 1986BL15, 1986ILZZ, 1987AS05; theor.).
In the range Ed = 380 to 570 keV, the scattering cross section is consistent with s-wave formation of the Jπ = 3/2+ state at 16.66 MeV. The excitation curves for Ed = 1.96 to 10.99 MeV show a broad resonance (Γ > 1 MeV) corresponding to Ex = 20.0 ± 0.5 MeV. From the behavior of the angular distributions an assignment of 2D3/2 or (2D, 4D)5/2 is favored, if only one state is involved: see (1979AJ01). A phase-shift analysis of the angular distribution and VAP data below 5 MeV suggests several MeV broad states [2P3/2, 4D7/2, 4D5/2, 4D3/2 and, possibly, 4D1/2]: see (1984AJ01). See also (1987KR18).
Angular distributions and analyzing powers have been measured at many energies to E = 44 MeV: see (1979AJ01, 1984AJ01) for the earlier work, (1982COZO, 1983COZR; Epol. d = 10 MeV; TAP; prelim.) and (1987YAZJ; Ed = 29.5 MeV on polarized 3He; prelim.). For d-3He correlations see (1987PO03). See also "Complex reactions" in the 5Li "GENERAL" section. See also (1987GR08) and (1981PL1A, 1983ZE06, 1983ZE1B, 1985SH08, 1986BO01, 1986KA28, 1986YA1E, 1987ZE1D; theor.).
The spectrum of protons at E(3He) = 3 to 18 MeV shows a pronounced peak corresponding to 5Lig.s. superposed on a continuum: see (1974AJ01). The angular distribution of p0 has been measured at E(3He) = 26 MeV (1983KI10; polarized target). See also 6Be and (1986OS1D; theor.).
Differential cross sections and polarization measurements have been carried out at many energies: see (1966LA04, 1974AJ01, 1979AJ01, 1984AJ01) for the earlier work. Recent measurements are reported at Epol. p = 65 MeV (1986FU05; Ay), 100 MeV (1983NAZV, 1985GUZX; σ(θ), Ay; prelim.) and 495 MeV (1988STZZ; prelim.) and at Ep = 695, 793, 890, 991 MeV (1985VE13; σ(θ)) and 1 GeV (1985AL09; σ(θ)). Cross sections and Ay at Epol. p = 98.7 and 149.3 MeV for the continuum are reported by (1985WE12).
Phase shifts below Ep = 18 MeV have been determined by (1977DO01) based on all the available cross-section and polarization measurements, using an R-matrix analysis program. The P3/2 phase shift shows a pronounced resonance corresponding to 5Lig.s. while the P1/2 shift changes slowly over a range of several MeV, suggesting that the first excited state is very broad and located 5 - 10 MeV above the ground state. The reduced widths of the P-wave resonance states are nearly the same. The D5/2, D3/2, F7/2 and F5/2 phase shifts become greater than 1° at Ep ≈ 11, 13, 14 and 16 MeV, respectively (1977DO01). (1986TH1C; prelim.) have measured Ay for 1.1 ≤ Epol. p ≤ 2.15 MeV: Ay = 1 for Ep = 1.89 MeV, θc.m. = 87.0°.
A phase-shift analysis for Ep = 21.8 to 55 MeV is presented by (1978HO17) [see also analyzing-power contour diagram for Ep = 20 to 65 MeV]. A striking anomaly is seen in the analyzing power at Ep = 23 MeV and the 2D3/2 phase shift clearly shows the 3/2+ state at Ex = 16.7 MeV [see also (1979AJ01)]. The other phase shifts 2S1/2, 2P3/2, 2P1/2, 2D5/2, 2F7/2, 2F5/2, 2G9/2 and 2G7/2 are smooth functions of energy. Both the 2P3/2 and 2P1/2 inelastic parameters show a somewhat anomalous behavior at Ep ≈ 30 MeV; the absorption first increases then decreases to stay rather constant at Ep > 40 MeV. These results are consistent with broad and overlapping states with Jπ = 1/2- and 3/2- at Ex ≈ 22 MeV. There is very little splitting of the real parts of the F-wave phase shifts up to 40 MeV. There is some indication (from the 2G7/2 phase shifts) of a 7/2+ level around Ep = 29 MeV [Ex ≈ 21 MeV]. The G-waves are necessary to fit the detailed shape of the angular distributions for Ep = 20 to 55 MeV (1978HO17). For a contour diagram of the analyzing power for Ep = 130 to 1800 MeV see (1980MO09). For a measurement of the spin rotation parameter, R, at Epol. p = 500 MeV see (1983MO01). See also (1986SA1J; prelim.; Epol. p = 65 MeV).
PNC effects have been studied via the elastic scattering of 46 MeV longitudinally polarized protons on 4He: the longitudinal power Az = -(3.3 ± 0.9) × 10-7. This was obtained by measuring σ+ and σ- for the positive and negative helicity of the incident protons (1985LA01, 1986LA29): the conclusion reached by the authors from this, and all other experiments, is that there does not exist any evidence for a non-zero value of fπ, the weak isovector coupling constant. See also (1984AJ01), (1986ADZT) and (1986HA1Q, 1988NA18; theor.).
Work at very high energies (≫ 1 GeV) is reported by (1982AB1B, 1984GL04, 1984SA39, 1985AB1A, 1985BA1H, 1985GL1B, 1986BE1S, 1987OT1D): see also reaction 7 and (1984AJ01). See also (1987MU1B). For α + p correlations see (1987PO03) and the "General" section here.
See also (1986GOZY), (1982NA1B, 1983FA1A, 1984FA1B, 1984FR1C, 1984HA1L, 1984HO1H, 1984SI1A, 1985AD1A, 1985AL1D, 1985FA1A, 1985MI10, 1986BA88, 1986ST1D), (1984SP1A; applications), (1984KR1B; muon fusion) and (1981PL1A, 1983AL1C, 1983BI1C, 1983GR20, 1983PA1B, 1983SA38, 1983ZA1A, 1983ZE06, 1983ZE1B, 1984AH03, 1984BL21, 1984CAZW, 1984DE1G, 1984FI20, 1984KW01, 1984LA1B, 1984PR1A, 1984SC1A, 1985BA68, 1985BLZX, 1985DA1A, 1985FL04, 1985HA04, 1985HE1D, 1985HO1B, 1985JA1F, 1985KI11, 1985KO05, 1985KO37, 1985MI1F, 1985NEZW, 1985RO16, 1985SO06, 1985SO08, 1985TE02, 1986AU05, 1986BA2L, 1986BL02, 1986BO01, 1986FR12, 1986GUZZ, 1986KA1G, 1986KA1H, 1986KA35, 1986KO1J, 1986OK06, 1986OR03, 1986SA05, 1986SA30, 1986WA21, 1987DU1B, 1987FO1C, 1987FR1D,19 87FU10, 1987KR16, 1987LI1K, 1987LI1L, 1987PO1G, 1987PR08, 1987QI01, 1987WA11, 1988FR06, 1988HE1C; theor.).
Angular distributions of deuterons and of 3He ions (reaction (a)) have been measured for Ep = 27.9 to 770 MeV and at Eα = 3.98 GeV/c [see (1979AJ01, 1984AJ01)] as well as at Epol. p = 100 MeV (1983NAZV; prelim.; also Ay), 200 and 400 MeV (1986AL01; also Ay). Excitation functions are reported at several energies in the range Ep = 38.5 to 44.6 MeV and 200 to 500 MeV. Continuum yields and Ay have been studied at Epol. p = 98.7 and 149.3 MeV by (1985WE12). For polarization measurements to 500 MeV see above and (1979AJ01, 1984AJ01). See also (1988BAZH).
For reactions (b), (c) and (d) see (1974AJ01, 1979AJ01, 1984AJ01). The breakup of 4He via reaction (c) has recently been studied by (1986FU05): large values of Ay in the FSI region are reported. For breakup processes at high energies, including pion production, see (1983AN13, 1983MO14, 1984WA1K, 1985BA1H, 1985GL1B, 1986BA2E, 1986BA2M). See also (1983AN18, 1987MUZZ, 1987TEZZ, 1988PA1E), (1983CH1B, 1987MU1B), (1983ZH04, 1984KO1E, 1984LI1B, 1986GO1J, 1987LY1C, 1987MI1N; theor.).
For reaction (a) see reaction 8 in 5He (1985WI15) and (1987KAZL; Ed = 15 MeV; n0; prelim.). Reaction (b) has been studied at Ed = 12 to 17 MeV and at Eα = 18.0 to 140 MeV: see (1979AJ01, 1984AJ01), 6Li and (1985DO03, 1987KUZI; theor.).
At Eα = 26.3 MeV, 5Lig.s. is reported to have a width of 1.9 ± 0.25 MeV while the first excited state is suggested to lie at Ex = 2.82 ± 0.35 MeV, Γ = 1.64 ± 0.25 MeV [reaction (b)]: see (1982NE09, 1986YA01). See also (1985NEZW).
Differential cross sections have been measured at Eπ = 75 and 150 MeV for p0: see (1984AJ01).
Angular distributions have been measured at Ep = 18.6 to 185 MeV. At the highest energy, the spectra are characterized by a broad asymmetric peak corresponding to 5Lig.s., a narrow peak [5Li*(16.7)] and a broad peak at Ex ≈ 20 MeV. DWBA analysis leads to C2S = 0.64 and 0.57 for 5Li*(0, 16.7). The first excited state of 5Li is also reported to be populated: see (1984AJ01).
Reaction (b) has been studied at Ep = 9 to 50 MeV: the p-α FSI corresponding to 5Lig.s. is observed [see (1979AJ01)]. See also (1983CA13, 1986NI1B). At 1 GeV (reaction (c)) the separation energy between 4 - 5 MeV broad 1p3/2 and 1s1/2 peaks is reported to be 17.7 ± 0.5 MeV (1985BE30, 1985DO16). See also (1985PA03; Ep = 70 MeV).
At E(3He) = 25.5 MeV, 5Li*(0, 16.7) and two broad peaks at Ex ≈ 19.8 and 22.7 MeV [Γc.m. = 2 and 1 MeV] are populated: see (1979AJ01). At E(3He) = 33.3 MeV angular distributions and analyzing powers have been studied for 5Li*(0, 16.7) [Γ ≈ 1.6 and ≈ 0.4 MeV]: see (1984AJ01). In reaction (b) the parameters of the first excited state are deduced to be Ex = 5.0 ± 0.7 MeV, Γc.m. = 5.7 ± 0.7 MeV (1984AR17; E(3He) = 1.7 and 2.3 MeV), Ex = 5.8 ± 0.5 MeV, Γc.m. = 5.2 ± 0.5 MeV (1987FA1I; E(3He) = 1.65 MeV). Angular distributions of protons from the decay of 5Lig.s. are reported by (1988BU04; E(3He) = 1.5 to 3.5 MeV). See also (1985BA1U, 1987ZA07), (1984AJ01) and 8Be.
Angular distributions have been measured at E(6Li) = 156 MeV to 5Lig.s.. Unresolved states at Ex = 16 - 20 MeV are also populated (1987MI34).
At Ep = 43.7 MeV, a triton group is observed to 5Li(0) (Γ = 1.55 ± 0.15 MeV): the angular distribution is consistent with a substantial mixing of L = 0 and 2 transfer. There is some evidence also for a very broad excited state between Ex = 2 and 5 MeV. 5Li*(16.7, 20.0) were not observed. The formation of 5Li*(16.7)(4S3/2) would be S-forbidden: the absence of 5Li*(20.0) would indicate that this state(s) is also of quartet character [see reaction 20 in 5He]. Weak, broad states at Ex = 22.0 ± 0.5 MeV and 25.0 ± 0.5 MeV and possibly 34 MeV are reported in a coincidence experiment in which three- and four-particle breakup was analyzed: see (1979AJ01). See also (1988BAZH). For reaction (b) at Ep = 670 MeV see (1984AJ01). See also (1985NEZW; theor.).
A kinematically complete experiment is reported at E(3He) = 120 MeV. The missing mass spectrum shows the ground-state peak and a 4 MeV wide bump at Ex ≈ 34 MeV, and some slight indication of a small bump at 22.0 ± 0.5 MeV (1985FR01).
At Eα = 90 MeV differential cross sections have been measured for the transitions to 5Lig.s. + 8Lig.s.: see (1984AJ01).