A=6Li (1974AJ01)

1. (a) ³He(³H, γ)⁶Li Q_m = 15.795 E_b = 15.795
(b) ³He(³H, p)⁵He Q_m = 11.20
(c) ³He(³H, p)⁴He + n Q_m = 12.0963
(d) ³He(³H, n)⁵Li Q_m = 10.13
(e) ³He(³H, d)⁴He Q_m = 14.3209
(f) ³He(³H, ³H)³He
(g) ³He(³H, dn)³He Q_m = -6.2576
(h) ³He(³H, p2n)³He Q_m = -8.4822
(i) ³He(³H, 2d)²H Q_m = -9.5267
(j) ³He(³H, pd)³H Q_m = -5.4938

Capture γ-rays (reaction (a)) to the first three states of ⁶Li [γ₀, γ₁, γ₂] have been observed for E(³He) = 0.5 to 20.0 MeV (1968BL10, 1970YO1A), 1 to 3 MeV (1963KO04), 5 to 20 MeV (1966NU01) and 5.4 to 25.8 MeV (1971VE10, 1973VE1B). In addition the yields of γ₃, γ₄ have been measured for E(³He) = 12.6 to 25.8 MeV (1971VE10, 1973VE1B). The γ₂ excitation function does not show resonance structure. However, the γ₀, γ₁, γ₃ and γ₄ yields do show broad maxima at E(³He) = 5.0 ± 0.4 [γ₀, γ₁], 20.6 ± 0.4 [γ₁], ≈ 21 [γ₃] and 21.8 ± 0.8 [γ₄] MeV. The magnitude of the ground state capture cross section is well accounted for by a direct capture model; that for the γ₁ capture indicates a non-direct contribution above E(³He) = 10 MeV, interpreted as a resonance due to a state with E_x = 25 ± 1 MeV, Γ_c.m. = 4 MeV, T = 1 (because the transition is E1, to a T = 0 final state) [the E1 radiative width |M|² ≳ 5.2/(2J + 1) W.u.], J^π = (2, 3, 4)^-, α + p + n parentage (1973VE09, 1973VE1B). The γ₄ resonance is interpreted as being due to a broad state at E_x = 26.6 MeV with T = 0. J^π = 3^- is consistent with the measured angular distribution (1973VE1B). The ground and first excited state reduced widths for ³He + t parentage, θ²₀ = 0.8 ± 0.2 and θ²₁ = 0.6 ± 0.3 (1971VE10, 1973VE09, 1973VE1B). (1970YO04) calculate that the upper limit to the t + ³He clustering is θ²₀ = 0.69, θ²₁ = 0.55, θ²₂ = 0.48 for the first states of ⁶Li.

Elastic scattering (reaction (f)) angular distributions have been measured at E(³He) = 5.00, 7.00, 9.00, 11.00 MeV (1968IV01), 5.8 to 19.9 MeV (1968BA76) and 27.7 and 32.3 MeV (1970BA29). Excitation functions are reported for E(³He) = 4.48 to 11.94 MeV (1968IV01), 4.3 to 21.4 MeV (1968BA76) and 24.7 to 33.4 MeV (1970BA29). At the lower energies the elastic yield is structureless and decreases monotonically with energy (1968IV01). Above E(³He) = 15 MeV a marked change in the angular distributions is attributed to a broad resonance in the l = 3 partial wave (1968BA76) which is reported by (1970BA29) to be located at ⁶Li*(29.0) [Γ ≈ 4 MeV] (see, however, reaction (a) above): the resonance is tentatively associated with the ¹F and ³F levels predicted from the one-channel resonating group theory (1967TH1C, 1968TH01). See also (1968OH04, 1973NO07) and (1972BR1Q, 1972JA1K, 1972KU20; theor.).

Angular distributions and total cross section measurements for reactions (b), (c) and (e) are listed in (1966LA04). Angular distributions of deuterons (reaction (e)) at E_t = 1.04 to 1.52 MeV (1969NA16), E_t = 1.51 to 3.27 MeV (1972WA1L) and at E(³He) = 0.29 to 0.80 MeV (1973NO07) are approximately (to within 1%) symmetric about 90°, as expected from isospin conservation: see also reaction 4. On the basis of a composite of available measurements (1973NO07) suggest that two broad resonances occur in the differential cross sections at θ_c.m. = 10° and 90° corresponding to ⁶Li states at E_x ≈ 16.2 MeV and ≈ 17 MeV, with J^π; T possibly 2⁺; 1 and 1^-; 0, respectively. For reaction (e) see also (1968ME03) and (1967BI1C; theor.). Measurements for reaction (c) lead to a n - p scattering length a_np = -21 ± 3 fm (1972KU08). See also (1968BL06, 1970BE1N, 1970GR17, 1971BE21, 1972KU1N, 1973RO2A, 1973SL03).

The angular distribution and polarization of the neutrons in reaction (d) has been measured at E(³He) = 2.70 and 3.55 MeV. The excitation function for E(³He) = 0.7 to 3.8 MeV decreases monotonically with energy (1971KL04). The excitation function for the n₀ group (θ_lab = 20°) has been measured for E(³He) = 14 to 26 MeV; evidence for a broad structure at E(³He) = 20.5 ± 0.8 MeV, Γ ≈ 6 MeV is reported [E_x = 26.1 MeV] (1973VE1B, 1974CH15). See also (1969VA1G, 1973GR1L, 1973LI19; theor.).

For reactions (g), (h), (i) and (j) see (1973SL03: E(³He) = 50 MeV): evidence for quasi-free reaction mechanism is observed in reactions (c), (i) and (j) and for d - d, p - ³He and d - ³He quasi-free scattering in reactions (i), (h) and (g), respectively.

2. ³H(α, n)⁶Li Q_m = -4.784

This reaction has been observed for E_α = 11.0 to 18.3 MeV: see ⁷Li. Neutron groups corresponding to ⁶Li*(0, 2.19) were detected (1967SP10).

3. ⁴He(d, γ)⁶Li Q_m = 1.4737

At E_d = 1.06 MeV [⁶Li*(2.19)], σ < 0.1 mb (1954SI07). At E_d = 3.1 MeV [⁶Li*(3.56)] Γ_d,α < 0.2 eV (1958WI15).

4. (a) ⁴He(d, n)⁵Li Q_m = -4.19 E_b = 1.4737
(b) ⁴He(d, p)⁵He Q_m = -3.12
(c) ⁴He(d, t)³He Q_m = -14.3209
(d) ⁴He(d, d)p + ³H Q_m = -19.8147
(e) ⁴He(d, d)d + d Q_m = -23.8476

For reaction (a) see ⁵Li, (1966LA04) and (1971NO1C). The proton yield (reaction (b)) gives no evidence of states in ⁶Li with 6.5 < E_x < 8.7 MeV (1964OH01). Polarization measurements at E_d = 8.5, 10 and 11 MeV (1971KE16) and 11 to 17 MeV (1972AV1E) indicate scattering through the first two states of ⁵He. The vector analyzing power has been measured at E_d = 32.1 and 41.0 MeV (1973CO2A, 1973DA1Q: detected ³H and ³He).

Studies of the t and ³He differential cross sections (reaction (c)) at E_α = 48.3 MeV (1971WA20) and at E_α = 49.9, 64.3 and 82.1 MeV (1970GR07, 1972GR07) show pronounced deviations from 90°_c.m. symmetry which are angle and energy dependent. [See analysis in (1973ED02)]. The observed asymmetries can be accounted for in terms of the p and the n separation energies in ⁴He (1972GR07). The asymmetry remains but is considerably smaller at E_α = 166 MeV (1973BA2U): it is attributed in part to Coulomb effects. See also (1969HA1Q, 1973FI04) and (1970RI16, 1971KO14, 1971MU17, 1972KN05, 1973BE2H; theor.).

For reactions (d) and (e) see (1972LI04: E_d = 52 MeV).

5. (a) ⁴He(d, d)⁴He E_b = 1.4737
(b) ⁴He(d, pn)⁴He Q_m = -2.22464

Elastic scattering differential cross-section measurements have been carried out previously at many energies up to 27.3 MeV: see (1966LA04) for a listing of the previous work. Recently, measurements have been reported at E_d = 2.48 MeV (1964MA50), 3 to 14 MeV (1968MA03), 12.00 MeV (1971JE01), 14.2 MeV (1967FU1D), 27.1 to 39.6 MeV (1969HA1Q) and at E_α = 166 MeV (1969BR19). Polarization measurements are listed in Table 6.3 (in PDF or PS). See also the reviews by (1966DA1B, 1971PL1C), (1972OH02) who set up a convenient parametrization for 1 + 0 → 1' + 0' polarization transfer phenomena, and (1973OH01, 1973OH02).

Phase shift analyses have been carried out for E_d = 0.3 to 4.2 MeV (1955GA74), 2 to 10 MeV (1967MC02), 3 to 10 MeV (1964SE07), 3 to 11 MeV (1970KE17), 3 to 11.5 MeV (1972SC14) and 10 to 27 MeV (1967DA1B). See also (1968MA03). (1973TH1F) have recalculated the phase shifts, including distortion of the deuteron cluster. This effect is important in the even-l cases. It leads to larger phase shifts than in calculations which do not include distortion, and in sharp resonance structure above 12 MeV. The pre '67 analyses were based on the analyses of differential cross section measurements; the newer ones also include the fitting of polarization measurements. On the basis of these analyses it is found that the d-wave shifts are split and exhibit resonance at E_x = 2.18 (³D₃), 4.8 (³D₂) and 5.7 MeV (³D₁): the parameters of these states are displayed in Table 6.4 (in PDF or PS). A good fit to all data below E_d = 11 MeV is found with partial waves of l ≤ 3 (1972SC14). The p-wave phase shifts are small which is strong evidence against the existence of the T = 0 p-wave triplet reported earlier by (1964SE07): see (1967MC02, 1969KO1N, 1970KE17, 1972SC14). For E_d = 11.5 to 17 MeV, the vector analyzing power iT₁₁ at a given angle is fairly constant (at θ_c.m. = 90° it is close to zero): this is also indicative of the absence of negative parity states in that region (1973CH35). At higher energies the l = 3 and 4 partial waves become important. The l = 0, 1 and 2 waves continue smoothly their low-energy behavior. [See, however, (1973TH1F)]. The interaction appears to be dominated by absorption (1967DA1B). See also (1969HA1Q, 1969KR14, 1969LI06).

In the range E_α = 30 to 80 MeV there is no difference in the cross sections for ²H(α, αp)n and ²H(α, αn)p, indicating that spin statistics play a dominant role in the deuteron breakup reactions and that charge and FSI effects are unimportant when quasi-free scattering conditions are satisfied (1972AL04). However, it is also found that the shapes of the quasi-free peaks do not remain the same for the two cases over the above energy range (1972AL1T). Reaction (b) appears to proceed at least partly via ⁶Li*(4.3) [whose E_x was assumed to be 4.57 MeV]. An upper limit for the T = 1 impurity amplitude of this state is estimated to be 10^-2 (1972DE49). For other work on reaction (b), see (1968WA01, 1970AS02, 1970BO1Q, 1972HO1H, 1973CH05) and reactions 9 in ⁵He and in ⁵Li. See also (1965TO01, 1967FU1D).

6. (a) ⁴He(³He, p)⁶Li Q_m = -4.020
(b) ⁴He(³He, n2p)⁴He Q_m = -7.7184

Angular distributions have been measured at E(³He) = 8 to 18 MeV (1967SP10; p₀), 11 to 18 MeV (1967SP10; p₁), 26 MeV (1965EC1A; p₀, p₁, p₂), 28 MeV (1971KL1E; p₀, p₁, p₂), E_α = 42 MeV (1970VI01; p₀, p₁) and 71.7 and 81.4 MeV (1973HA50: formation of ⁶Li*(0, 2.19, 3.56)). At E_α = 63.7, 71.7 and 81.4 MeV, the α spectra show that the sequential decay (reaction (b)) involves ⁶Li*(2.19) and possibly ⁵Li (1973HA50). See also (1961CH09, 1970BA1V) and ⁷Be.

7. ⁶He(β^-)⁶Li Q_m = 3.510

See ⁶He.

8. ⁶Li(γ, γ)⁶Li

The width, Γ_γ, of ⁶Li*(3.56) is 8.1 ± 0.5 eV. Γ_α,d for the forbidden decay of this state into α + d is < 1.3 eV (1969RA20). The measurements by (1968CR07) are incorrect: see the discussion in (1969RA20). (1973SA21) reports Γ_γ = 6.5^+2.4_-1.7 eV. See also Table 6.5 (in PDF or PS) and (1966LA04).

9. (a) ⁶Li(γ, n)⁵Li Q_m = -5.66
(b) ⁶Li(γ, p)⁵He Q_m = -4.59
(c) ⁶Li(γ, d)⁴He Q_m = -1.4737
(d) ⁶Li(γ, t)³He Q_m = -15.7946
(e) ⁶Li(γ, pd)³H Q_m = -21.288
(f) ⁶Li(γ, nd)³He Q_m = -22.052

Measurements of reaction (a) with monochromatic γ-rays have been made for E_γ = 5.4 to 9.0 MeV (1964GR40) and 10 to 32 MeV (1965BE42). The cross section for reactions (a), (b) and (f) shows a possible peak at 6.75 MeV (1964GR40), a maximum at ≈ 12 MeV (σ ≈ 1.6 mb) and a gentle decrease to 0.6 mb at 32 MeV (1965BE42). Other maxima in the cross section for neutron production are reported in (1965BA16, 1965HA19, 1966CO1B, 1966PA12) and in (1966LA04). See also (1966HI1B, 1968OD1A).

The cross section for photoproton production (reaction (b)) is generally flat up to 90 MeV with a slight evidence of a hump at ≈ 16 MeV excitation (1970WO10). Additional peaks are reported by (1969SO13). The energy distribution of the photoprotons has been measured at E_brem. = 95 to 102 MeV: the data are consistent with the predictions of the quasi deuteron model with a characteristic pair momentum parameter of 80 MeV/c (1968MA19). See also (1965BA16, 1965MA46, 1967DE12, 1973DE17, 1973GA16), (1973CO1N) and ⁵He.

The cross section for reaction (c) is ≲ 5 μb in the range E_γ = 2.6 to 17 MeV consistent with the expected inhibition of dipole absorption by isospin selection rules: see (1959AJ76, 1966LA04). See also (1965MA46) and (1973PA17).

The cross section for reaction (d) shows a peak at E_γ ≈ 21 MeV with σ_max = 5.1 mb. The angular distribution of the tritons at that energy is asymmetric around 90°, indicating interference between E1 and E2 absorption (1968MU1A, 1970MU05). Between 19 and 35 MeV the cross section decreases from 0.46 ± 0.24 mb to 0.11 ± 0.06 mb (1968SH10). See also (1965BA16, 1965MA46, 1970WO10, 1973DE17), and (1966LA04). The cross sections reported in this reaction are not in agreement with those found in the inverse reaction: see reaction 1 and e.g. (1973VE09, 1973VE1B). For reaction (e) see (1968MU1A, 1970MU05, 1973DE17).

See also the review articles by (1966FU1C, 1967SH1E, 1968SC1B, 1973AR1L), (1965DA06, 1966SH06, 1969ME1D, 1972CR1E) and (1966FE1B, 1966KU12, 1967AU1C, 1967NE1C, 1968CO13, 1969CL1D, 1969MA1N, 1970KU02, 1971AU01, 1971GH1A, 1971GH1B, 1971MU19, 1972KU05, 1972WE03, 1973MA2C, 1973RA1G, 1973SH08, 1973SR1B; theor.).

10. (a) ⁶Li(e, e)⁶Li
(b) ⁶Li(e, ep)⁵He Q_m = -4.59
(c) ⁶Li(e, ed)⁴He Q_m = -1.4737

Elastic scattering has been measured at E_e = 85 to 140 MeV (1966RA29), 200 to 499 MeV (1971LI10) and 200 to 600 MeV (1967SU1A). The elastic scattering shows a diffraction minimum at q² = 8 fm^-2. The diffraction feature in F² indicates a lowering of the central charge density (1971LI10). A model-independent analysis of the scattering yields r_rms = 2.51 ± 0.10 fm (1972BU01). See also (1967SU1A, 1969MO1J, 1971LI10, 1971NE03). Measurement of the ratio of elastic charge scattering from ⁶Li and from ⁷Li as a function of (momentum transfer)² yields < r² >^1/2₆/< r² >^1/2₇ = 1.001 ± 0.008 (1971VA20).

The population of excited states of ⁶Li has been reported at E_e = 41 to 59 MeV (1969EI06: ⁶Li*(2.19, 3.56, 4.27, 5.37)), 63 to 128 MeV (1968HU03, 1968HU1C, 1969HU05: ⁶Li*(3.56)), 89 to 175.4 MeV (1971NE03: ⁶Li*(2.19, 3.56, 5.36)), 109.0 to 166.9 MeV (1969NE1B: ⁶Li*(3.56)), 109.0 to 281.7 MeV (1969NE1B: ⁶Li*(2.19)) and 200 and 499 MeV (1971LI10: ⁶Li*(2.19)). The inelastic electron groups are superposed on a rather large quasi-continuous background [see, e.g., (1969HU05)]. See also (1968EI03, 1970BR1E, 1972THZF, 1973TH1B, 1973YE1B). Table 6.5 (in PDF or PS) summarizes the results. See (1966LA04) for a summary of the earlier reported results.

Because of the astrophysical implications of a 0⁺ state in ⁶Be near the ³He + ³He binding energy, several attempts have been made to locate the analog state in ⁶Li at E_x ≈ 15.2 MeV. The results were negative: Γ_γ < 11 eV for the M1 width of the 0⁺ → 1⁺ transition to the ground state of ⁶Li (1973CA1M: E_e = 65 MeV; looked a E_x = 9.0 to 16.8 MeV), Γ_γ < 3 eV (1973FA04: E_e = 37, 50, 60 MeV), Γ_γ < 8.8 eV (1973BI1M: E_e = 100 MeV).

The harmonic oscillator parameters of the 1p and 1s shells in ⁶Li are q_p = 50 ± 5 MeV/c and q_s = 108 ± 9 MeV/c (1972AN27). For reaction (b) see also (1970WO10, 1971HE1K, 1973HE1L) and ⁵He. For reaction (c) see (1966AL1F, 1971HE1K, 1972GE1H, 1973HE1L, 1973JU1E). See also (1972TI03).

11. ⁶Li(n, n')⁶Li*

Angular distributions have been reported at E_n = 1.00 to 2.30 MeV (1967KN1A; n₀), 4.8, 5.7, 7.5 MeV (1968HO03; n₀), 10 MeV (1967CO01; n₀, n₁), 14.0 MeV (1966ME1C; n₀, n₁) and 14.2 MeV (1970AB04; n₀, n₁). See (1966LA04) for earlier references. The population of ⁶Li*(3.56) is weak: see (1966LA04, 1968HO03). See, however, (1966ME1C). See also (1971MI12; theor.) and ⁷Li.

12. (a) ⁶Li(p, p)⁶Li
(b) ⁶Li(p, 2p)⁵He Q_m = -4.59
(c) ⁶Li(p, pd)⁴He Q_m = -1.4737
(d) ⁶Li(p, p³H)³He Q_m = -15.795
(e) ⁶Li(p, pn)⁵Li Q_m = -5.66
(f) ⁶Li(p, 2d)³He Q_m = -19.828

Proton angular distributions have been measured recently at E_p = 3.6 to 9.4 MeV (1967HA07, 1967HA08; p₁), 4.3 to 9.4 MeV (1967HA07, 1967HA08; p₂), 14.0 MeV (1968ME25; p₀, p₁, p₂), 24.4 MeV (1968AU05, 1968AU06; p₂), 25.9, 29.9, 35.0, 40.1, 45.4 MeV (1972BR20; p₀, p₁), 25.9, 45.4 MeV (1972BR20; p₂), 33.6 MeV (1970KU1D; p₀), 49.8 MeV (1971MA13, 1971MA44; p₀, p₁), 100 MeV (1968LI1C; p₀), 144 MeV (1972JA07; p₀), 152 MeV (1966RO1C; p₀), 155 MeV (1968GE04; p₀), 155 MeV (1965JA1A: ⁶Li*(2.2 ± 0.05, 3.6 ± 0.1, 4.5, 5.5)), 185 MeV (1970HU13; p₀, p₁, p₂) and 600 MeV (1973GA1M; p₀). See also (1970KO36). See (1966LA04) for a listing of the earlier references.

Inelastic groups corresponding to excited states of ⁶Li are displayed in Table 6.6 (in PDF or PS): no others appear for E_x < 16 MeV (1968MA02). See also (1969KO1M, 1970BA1V) and (1968GL1A, 1968NE1B, 1969MA1G, 1969NE1A, 1969TI02, 1969WA11, 1973RA04; theor.).

Angular correlations of protons (reaction (b)) corresponding to ⁵He(0) show an l = 1 character, but with an anomalously low peak-to-valley ratio, as compared e.g. with ⁷Li, suggesting a significant s-wave contribution (1967RO06: E_p = 156 MeV); and see discussion in (1972MA61) relating both to this transition and to the one involving ⁵He*(16.8). See also (1965BE1E, 1970TH1F, 1972MI1N, 1973MI1J, 1973CO2B), (1966LA04) and (1966JA1A, 1967JA1C, 1967JA1D, 1967JA1E, 1968KU1B, 1968SA1C, 1968TA1K, 1969JA1D, 1969KO1J, 1971KO27, 1973BA65, 1973CH1Q; theor.)

Reaction (c) has been studied at E_p = 9 and 10 MeV (1968VA02), 19 MeV (1971LI1N, 1973LI22), 45 MeV (1970BR1N), 56.5 and 61.5 MeV (1969RO04, 1970JA17), 100 MeV (1971MA61, 1973GO2A), 118.1 MeV (1972BA2L), 156 MeV (1968BA09, 1973BA01), 590 MeV (1972AL21, 1973KI1M) and 1 GeV (1967SU1C). At E_p = 590 MeV, in a kinematically complete experiment, the width of the momentum distribution of a deuteron in ⁶Li is found to be 124 ± 4 MeV/c (1972AL21) [see also preliminary report by (1973KI1M)], while (1970JA17) find 70 ± 8 MeV/c at E_p = 56.5 MeV. See also (1973CH1R). The probability for a deuteron cluster in ⁶Li is estimated to be 0.45 ± 0.08 (1971MA61), 0.13 ± 0.05 (1973LI22). At E_p = 9 and 10 MeV sequential decay via ⁶Li*(0, 2.19, 4.6, 6.0) dominates the yield: the final state interactions do not support the previously proposed [see (1966LA04)] negative-parity states in ⁶Li (1968VA02). See also (1966SE1C, 1971GA1J, 1973CO2B), (1968KO1E) and (1965NE1B, 1966ZE1A, 1968RO1F, 1969BO1G, 1969HO1K, 1969JA13, 1969NA1H, 1970JA1L, 1970MI1J, 1973RO2B; theor.). See also reaction 9 in ⁷Li (1973WE07).

Angular correlation studies in reaction (d) give evidence for an appreciable ³He + ³H configuration in ⁶Li(0) (1968BA09, 1970BA1T, 1973GO2A). At E_p = 590 MeV, in a kinematically complete experiment, the width of the momentum distribution is determined to be 168 ± 34 MeV/c (1973DO12). See also (1969KO1G, 1973RA1G) and ⁷Be. For reaction (e) see (1972MI1N, 1973MI1J). For reaction (f) see (1973CO2B).

13. (a) ⁶Li(d, d')⁶Li*
(b) ⁶Li(d, pn)⁶Li Q_m = -2.22464
(c) ⁶Li(d, 2d)⁴He Q_m = -1.4737
(d) ⁶Li(d, αt)¹H Q_m = -2.559
(e) ⁶Li(d, α³He)n Q_m = -1.795

Angular distributions of deuterons have been measured at E_d = 4.5 to 5.5 MeV (1970PO03; d₀), 8 to 12 MeV (1970BI1B, 1971BI11; d₀), 11.8 MeV (1968LU02; d₀, d₁), 14.7 MeV (1969MA13; d₀, d₁) and 19.6 MeV (1971CHYH; d₀). The T = 1, 0⁺ state, ⁶Li*(3.56), is not appreciably populated. See also (1966LA04) and (1966BR1G). ⁶Li*(4.31) has been studied at E_d = 20 and 25 MeV: a single-level, many-channel fit yields Γ = 1.82 ± 0.11 MeV (1975BR21). See also (1968LE15). See Table 6.6 (in PDF or PS) for a summary of the results on excited states.

At E_d = 21 MeV reaction (b) shows spectral peaking (characteristic of ¹S₀ for the pn system [T = 1]) when ⁶Li*(3.56) is formed, in contrast with the much broader shape (characteristic of ³S₁) seen when ⁶Li*(0, 2.19) are populated (1972BR03). See also (1973CH05). A study of reaction (c) at E_d = 52 MeV shows that the α-clustering probability, N_eff = 0.12^+0.12_-0.06 if a Hankel function is used (1973HA31) [see this reference also for a discussion of other results on momentum distributions and α-clustering probability in ⁶Li]. The α-particle and the deuteron clusters in ⁶Li have essentially a relative orbital momentum of l = 0. The D-state probability of the ground state of ⁶Li is ≈ 5% of the S-state (1973HA31). Quasi-free scattering is an important process even for E_d = 6 to 11 MeV (1973MI20). Interference effects are evident in reaction (c) proceeding through ⁶Li*(2.19, 4.31): this is due to the experiment being unable to determine whether the detected particle was emitted first or second in the sequential decay (1968LE15). See also (1973JA21). For reactions (d) and (e) see (1968LE15) and (1974GR02).

14. ⁶Li(³He, ³He)⁶Li

Angular distributions have been measured at E(³He) = 8 to 20 MeV (1968LU02: g.s.), 21, 24 and 27 MeV (1966VA1B, 1967BL1E: g.s., 2.19), 24.6 and 27 MeV (1971GI1E, 1972GI07: g.s., 2.19, 3.56), 34 MeV (1971CHYH: g.s.) and 217 MeV (1973WI07: g.s.). At E(³He) = 24.0 MeV the population of ⁶Li*(0, 2.19, 3.56, 4.53, 5.37) is reported by (1973VE1B). See also (1967CO1J) and (1973DU1D; theor.).

15. (a) ⁶Li(α, α')⁶Li*
(b) ⁶Li(α, 2α)²H Q_m = -1.4737

Angular distributions (reaction (a)) have been measured at E_α = 3.0 and 4.0 MeV (1972BO07; α₀), 12.54 to 18.54 MeV (1970BI1B, 1971BI12; α₀), 25 MeV (1968DO13; α₀, α₁), 29.4 MeV (1968MA25, 1969MA13; α₀, α₁), 36.5 MeV (1971CHYH; α₀), 104 MeV (1968HA1D, 1969HA14, 1970HA1G; α₀) and 166 MeV (1972BA89; α₀). See (1966LA04) for earlier references. In the range E_α = 12.5 to 18.5 MeV the optical model gives good agreement with the elastic angular distributions when a target spin-orbit potential is included (1971BI12). At E_α = 104 MeV the elastic angular distribution shows a pronounced diffraction pattern (1969HA14) while at 166 MeV there is some backward peaking in addition to a single strong forward peak (1972BA89). See also (1969TR1B, 1970FO1B, 1970MI1J, 1973CL1K; theor.) and (1969HO1K).

Reaction (b) has been studied by (1969PU01, 1970WA1U, 1971WA19) at E_α = 50.4, 59.0, 60.5, 70.3 and 79.6 MeV. At each of these energies several coincident energy spectra of the two α-particles were taken, with special emphasis on those angles at which zero lab momentum is possible for the residual deuteron. From the measurements at these particular angles, off-mass-shell α - α cross sections were extracted and were found to be in excellent agreement with the free α - α cross sections at comparable energies: see ⁸Be. The momentum distribution for α-particles in ⁶Li has a width of 29 ± 2 MeV/c. The effective number of α + d clusters for ⁶Li(0), N_eff = 0.08 ± 0.04. The knockout process appears to occur only in the nuclear surface region (1971WA19).

Reaction (b) has also been studied at E_α = 23.6 MeV (1969BA18), 25 MeV (1968DO13, 1969DO02), 29.4 MeV (1968MA25), 37.5 and 43.5 MeV (1971DE15), 42.8 MeV (1970GA14), 55 MeV (1968PI04, 1969PI11, 1970PI1D), 64.3 MeV (1970JA17). See also (1967MO1F, 1969VE1B, 1973JA21, 1974DO1G). The reaction ⁶Li(α, αx)Y has been studied at E_α = 50 MeV [x = p, d, t, ³He, α]: p, d, and α clustering is strong, t and ³He clustering is weak (1971LA20). See also (1968BA1H, 1969DO03, 1970BU1C, 1970MI12, 1972KO1J, 1972AV04; theor.).

16. ⁶Li(⁶Li, ⁶Li)⁶Li

Angular distributions of elastically scattered ⁶Li ions have been measured at E(⁶Li) = 3.2 to 7.0 MeV (1966PI02), 8 to 14.5 MeV (1973GR34), 12, 20 and 28 MeV (1971FO08), 30 MeV (1971DA33), 32.0 MeV (1970NA02: also ⁶Li*(3.56)), and 32.0 and 36.0 MeV (1973WH02: for both ⁶Li*(3.56)). A microscopic DWBA analysis (including the tensor interaction and exchange) gives good agreement with the data (except at forward angles) and with the cross sections for this reaction and for the reaction to the analog ground states of ⁶He and ⁶Be (1973WH02). See also reaction 9 in ⁶He. (1971FO08) report that the reaction mechanism is dominated by absorption. See also ¹²C in (1975AJ02) and (1972CL14, 1973PE13; theor.).

17. ⁶Li(¹⁶O, ¹⁶O)⁶Li

At E(¹⁶O) = 36 MeV the elastic angular distribution has been measured by (1971OR02).

18. ⁷Li(n, 2n)⁶Li Q_m = -7.251

See (1965GO1C, 1969VA1F) and ⁸Li.

19. ⁷Li(γ, n)⁶Li Q_m = -7.2506

See (1969GA1M, 1969ME1D, 1969MU1C) and ⁷Li.

20. (a) ⁷Li(p, d)⁶Li Q_m = -5.026
(b) ⁷Li(p, 2d)⁴He Q_m = -6.500
(c) ⁷Li(p, pd)⁵He Q_m = -9.61

Angular distributions of deuterons (reaction (a)) have been recently studied at E_p = 30.3 MeV (1969DE04: ⁶Li*(0, 2.19, 3.56)), 33.6 MeV (1967KU10, 1970KU1D: ⁶Li*(0, 2.19, 3.56, 5.37)), 100 MeV (1968LE01, 1969LI02: ⁶Li*(0, 2.19, 3.56, 5.6)) and 155.6 MeV (1968BE72, 1969BA05, 1969TO1A: ⁶Li*(0, 2.2 ± 0.08, 3.6 ± 0.1, 4.5 ± 0.15, 5.5 ± 0.1)). No states other than those reported above have been observed up to E_x = 18 MeV (1967KU10), 20 MeV (1969BA05). See also (1966LA04) and (1970BA1V, 1972AZ03). At E_p = 12 MeV (1969CO06) have studied the ratio of the cross section of the (p, d) reaction to that for the (p, d) reaction, in which singlet deuterons are formed: σ(p, d)/σ(p, d) = 41.0.

A kinematically complete experiment at E_p = 45 MeV shows that reaction (b) proceeds via low lying excited states of ⁶Li (1972FU07). See also (1967JO1B). For reaction (c) see (1969DE04).

21. ⁷Li(d, t)⁶Li Q_m = -0.993

The angular distributions of the tritons to ⁶Li*(0, 2.19, 3.56) at E_d ≈ 15 MeV indicate l_n = 1, and therefore even parity, for the first three states of ⁶Li: see (1966LA04). A careful study at E_d = 10 - 12 MeV, in a region in ⁹Be which is free of sharp resonances, shows that the t₀ angular distributions which have both fore and aft maxima can be reproduced using a multi-interaction, exact finite-range two-mode DWBA formalism (1970ZE1C, 1971ZA07, 1973WE09).

A study at E_d = 23.6 MeV of the relative cross sections of the analog reactions ⁷Li(d, t)⁶Li (to the first two T = 1 states at 3.56 and 5.37 MeV) and ⁷Li(d, ³He)⁶He (to the ground and 1.80 MeV excited state) shows that ⁶Li*(3.56, 5.37) have high isospin purity (α² < 0.008): this is explained in terms of antisymmetrization effects which prevent mixing with nearby T = 0 states (1971DE08). See also (1970BA1V) and (1971WE1L, 1973DU1D; theor.).

22. ⁷Li(³He, α)⁶Li Q_m = 13.328

Angular distributions have been reported at E(³He) = 5.1 to 12 MeV (1969LI06; α₁), 5.1 and 7.5 MeV (1969LI06; α₂), 5.5 to 9.0 MeV (1969LI06; α₀), 6.0 and 7.5 MeV (1970OR03; α₀, α₁, α₂), 8.7 MeV (1969MA1J; α₁), 8.7 and 9.7 MeV (1969MA1J; α₀), 16 to 18 MeV (1970ZE1C, 1971ZA07; α₀) and 21, 24 and 27 MeV (1966VA1B, 1967BL1E; α₀, α₁, α₂). See also (1969OR01) and ¹⁰B. At E(³He) = 16 to 18 MeV, in a region where there are no sharp or strong resonances in the compound nucleus, both the forward and the backward maxima in the α₀ angular distributions are reproduced by conventional DWBA without inclusion of exchange terms. However, the cross section derived from zero range DWBA is a factor of 25 smaller than the observed cross section. For finite range analysis no appreciable renormalization is necessary (1971ZA07). See also (1973WE1V; theor.).

At E(³He) = 3.8 to 5 MeV, α groups are observed to the ground state and to excited states at E_x = 2.17 ± 0.02, 3.55 ± 0.02 and 5.34 ± 0.02 MeV [Γ = 560 ± 40 keV]: no evidence is seen for other excited states below E_x = 10 MeV previously reported by (1960AL10), even after a spectrum was taken at the energy [E(³He) = 0.9 MeV] at which the earlier work was done (1968CO07). (1969LI06) observe states at E_x = 2.179 ± 0.008, 3.568 ± 0.008 and 5.36 ± 0.03 MeV [Γ ≈ 0.54 ± 0.04 MeV].

At E(³He) = 11 to 12 MeV only structureless broad spectra are observed in the region 15.6 ≤ E_x ≤ 16 MeV: there is no evidence for a sharp T = 1 analog of a state in ⁶Be near the ³He + ³He binding energy postulated for astrophysical considerations (1972MA1W).

Several attempts have been made to look at the isospin decay of ⁶Li*(5.37) [J^π = 2⁺; T = 1] via ⁷Li(³He, α)⁶Li* → d + α: the branching is < 2% (1971CO22), < 1% (1973BR20). If Γ(5.37) = 560 keV [see above] Γ_d ≤ 12 keV and θ²_d(5.37) ≤ 0.5% (1971CO22). See, however, (1973BR20). Γ_p/Γ = 0.35 ± 0.10 and Γ_p+n/Γ = 0.65 ± 0.10 for ⁶Li*(5.37) (1973AR05). See also (1970KA1M, 1971AR37, 1972KA08) and (1966LA04).

23. ⁹Be(γ, t)⁶Li Q_m = -17.689

See (1959AJ76).

24. (a) ⁹Be(p, α)⁶Li Q_m = 2.125
(b) ⁹Be(p, d)⁴He⁴He Q_m = 0.651
Q₀ = 2.1254 ± 0.0018 (1967OD01: see also (1967SP09)).

Angular distributions of α-particles (reaction (a)) have been measured at E_p = 0.11 to 0.60 MeV (1973SI27; α₀), 0.3 to 0.9 MeV (1968BE1N; α₀), 6 to 11.5 MeV (1963BL20; α₀, α₁), 5.9 and 7 MeV (1964YA1A; α₀, α₁), 15.6 and 18.6 MeV (1962MA40; α₀, α₁), 26.7 and 38 MeV (1967AC01, 1969GA03, 1970GU06; α₀, α₁) and 45 MeV (1970DE17, 1971DE2B, 1971PE10, 1972DE01, 1972DE02; α₀, α₁, α₂ and ⁶Li*(0, 3.56)). At E_p = 45 MeV the reaction appears to proceed by a direct process, with a rise at back angles attributed to a pickup process. The 3.56 MeV state decays by γ-emission: E_γ = 3.572 ± 0.012 MeV; the internal pair spectrum is consistent with an M1 transition (1954MA26). The α-decay of ⁶Li*(3.56) is forbidden by spin and parity conservation: Γ_α/Γ is measured to be < 0.025 (1971AR37). See also (1972KO1N). For the decay of ⁶Li*(5.37) see reaction 22 (1973AR05). See also (1966DO1A, 1966LA20, 1970MA1K) and (1969TH1D, 1973ED02; theor.). See also ¹⁰B and (1966LA04).

At E_p = 9 MeV, the yield of reaction (b) is dominated by final state interactions through ⁸Be*(0, 2.9) and ⁶Li*(2.19) with little or no yield from a direct three-body decay (1971EM01). See also (1967FI1D).

25. ⁹Be(d, ⁵He)⁶Li Q_m = -0.99

Not reported: see (1964BL1C).

26. ⁹Be(t, ⁶He)⁶Li Q_m = -5.386

Angular distributions of ⁶He_g.s. + ⁶Li_g.s., ⁶Li_g.s. + ⁶He_g.s., ⁶Li^*_3.56 + ⁶He_g.s., and ⁶He_g.s. + ⁶Li^*_3.56 [the second listed ion being the detected one] have been measured at E_t = 23.5 MeV. In the latter two cases the final state is composed of two isobaric analog states: angular distributions are symmetric about 90°_c.m., within the overall experimental errors. In the reaction leading to the ground states of ⁶He and ⁶Li differences from symmetry of as much as 40% are observed at forward angles.

Angular distributions involving ⁶He_g.s. + ⁶Li*(2.19) and ⁶Li_g.s. + ⁶He*(1.8) have also been measured (1973VO08).

27. ⁹Be(³He, ⁶Li)⁶Li Q_m = -1.895

Angular distributions of the ⁶Li ions have been obtained at E(³He) = 6, 7, 8 and 10 MeV (1969TA05) and 7.0 and 9.0 MeV (1972YO02): these and the fairly smooth yield curves for E(³He) = 6 to 9 MeV [see ¹²C in (1975AJ02)] seem to suggest that the mechanism of the reaction is essentially direct. The triton spectroscopic factors in ⁹Be are determined to be 0.073 and 0.052 at 7 and 9 MeV, respectively (1972YO02). See also (1971ZE03; theor.).

28. (a) ¹⁰B(γ, α)⁶Li Q_m = -4.460
(b) ¹⁰B(p, pα)⁶Li Q_m = -4.460
(c) ¹⁰B(d, dα)⁶Li Q_m = -4.460
(d) ¹⁰B(α, 2α)⁶Li Q_m = -4.460
(e) ¹⁰B(α, ⁸Be)⁶Li Q_m = -4.552

For reactions (a) and (b), see reactions 23 and 28 in ¹⁰B. For reaction (c) see (1970NA06). Reaction (d) has been studied at E_α = 28.4 MeV (1967TA1C). Reaction (e) has been studied at E_α = 46 MeV (1970ZE03). See also (1966GE12) and ¹⁰B.

29. ¹⁰B(d, ⁶Li)⁶Li Q_m = -2.987

At E_d = 19.5 MeV angular distributions have been measured for the ⁶Li ions to ⁶Li*(0, 2.19). The experimental cross sections of the ground state transition are two orders of magnitude greater than those predicted by the shell model, consistent with the cluster nature of ⁶Li (1971GU07). See also (1972GA1E).

30. ¹⁰B(³He, ⁷Be)⁶Li Q_m = -2.874

Angular distributions of the ⁷Be ions [⁷Be*(0, 0.43)] corresponding to formation of ⁶Li*(0, 2.19) have been measured at E(³He) = 30 MeV (1970DE12, 1972OH01).

31. ¹⁰B(¹⁶O, ²⁰Ne)⁶Li Q_m = 0.270

See (1968OK06).

32. ¹¹B(d, ⁷Li)⁶Li Q_m = -7.192

Angular distributions of ⁶Li ions are reported at E_d = 19.5 MeV for transitions to ⁷Li*(0, 0.48) (1971GU07). At E_d = 40 MeV the cross section for the transition to ⁶Li*(3.56) is half the cross section for the reaction ¹¹B(d, ⁷Be)⁶He to the analog state (the ground state of ⁶He) [to within 10%] as predicted by isospin conservation (1972GO1P).

33. ¹¹B(³He, ⁸Be)⁶Li Q_m = 4.570

Angular distributions of ⁶Li ions are reported at E(³He) = 3.0 and 5.2 MeV. The reaction has been observed to lead to ⁸Be*(2.9) + ⁶Li(0) and to ⁸Be(0) + ⁶Li*(3.56). It is suggested that ⁶Li*(3.56) contains a far smaller admixture of the (³He + t) configuration than does ⁶Li(0) (1964YO06, 1967YO02). See also (1967YO1C).

34. ¹²C(p, ⁷Be)⁶Li Q_m = -22.569

Angular distributions of the ⁶Li ions corresponding to the transition to ⁷Be*(0 + 0.43) have been measured at five energies in the range E_p = 36.0 to 56.8 MeV and the data have been analyzed using zero-range and finite-range DWBA assuming the pickup of ⁵He and ⁶Li clusters as the dominant mechanism. The differential cross sections decrease with energy: at E_p = 36 MeV, dσ/dΩ as large as 200 μb/sr are observed (1971HO1K, 1971HO25). The angular distribution has also been measured at E_p = 45 MeV by (1971BR07).

35. ¹²C(d, ⁸Be)⁶Li Q_m = -5.893

Angular distributions of ⁶Li ions are reported at E_d = 19.5 MeV (1971GU07: transition to ⁸Be(0)) and at 51.8 MeV (1970EI05: transitions to ⁸Be*(0, 2.9)).

36. ¹²C(³He, ⁹B)⁶Li Q_m = -11.571

Angular distributions of ⁶Li ions have been obtained at E(³He) = 28 MeV (1971KL1E), 30.0 and 40.7 MeV (1972OH01) and 35.7 MeV (1969ZE1A, 1970FO1D).

37. ¹²C(α, ¹⁰B)⁶Li Q_m = -23.715

Angular distributions have been obtained of ⁶Li and ¹⁰B ions corresponding to transitions to ⁶Li*(0, 2.19) and ¹⁰B*(0, 0.72, 2.15) (1972RU03: E_α = 42 MeV).

38. ¹²C(⁶Li, ¹²C)⁶Li

See ¹²C in (1968AJ02, 1975AJ02) and (1968NO1C; theor.).

39. ¹³C(p, ⁸Be)⁶Li Q_m = -8.615

At E_p = 45 MeV, the angular distributions of the ⁶Li ions corresponding to the transitions to ⁸Be*(0, 2.9) have been measured: the cross sections, integrated from 20° to 85° c.m., are, respectively, 1.9 and 2.7 μb (1971BR07).

40. (a) ¹⁴N(α, ¹²C)⁶Li Q_m = -8.799
(b) ¹⁴N(α, αd)¹²C Q_m = -10.2725

For reaction (a) see ¹²C in (1968AJ02, 1975AJ02). Reaction (b), studied at E_α = 22.9 MeV, appears to involve ⁶Li*(2.19) (1969BA17).

41. ¹⁶O(p, ¹¹C)⁶Li Q_m = -22.185

See (1969HO1H).

42. ¹⁶O(d, ¹²C)⁶Li Q_m = -5.688

Angular distributions of ⁶Li ions have been obtained at E_d = 19.5 MeV corresponding to formation of ¹²C*(0, 4.4) (1971GU07). See also ¹²C in (1968AJ02, 1975AJ02).

43. ¹⁶O(³He, ¹³N)⁶Li Q_m = -9.238

Angular distributions of ⁶Li ions have been measured at E(³He) = 30.0 and 40.7 MeV (1972OH01). See also ¹³N in (1970AJ04).

44. ¹⁶O(α, ¹⁴N)⁶Li Q_m = -19.263

Angular distributions have been obtained of ⁶Li and ¹⁴N ions corresponding to the population of the ground states (1972RU03: E_α = 42 MeV).

45. ¹⁹F(d, ¹⁵N)⁶Li Q_m = -2.539

Angular distributions of ⁶Li ions have been measured corresponding to formation of ¹⁵N*(0, 5.3, 6.3) (1971GU07: E_d = 19.5 MeV). See also ¹⁵N in (1970AJ04).

46. ¹⁹F(³He, ¹⁶O)⁶Li Q_m = 4.095

Angular distributions have been measured at E(³He) = 11 MeV (1971ST06: ⁶Li_g.s. + ¹⁶O_g.s., ⁶Li_g.s. + ¹⁶O_6.06+6.14, ⁶Li_3.56 + ¹⁶O_g.s.), 22.4, 30.0 and 40.7 MeV (1972OH01: ⁶Li_g.s. + ¹⁶O_g.s. except at 30.0 MeV where also ⁶Li_3.56 + ¹⁶O_g.s.) and at 28 MeV (1970KL09: ⁶Li_g.s.+¹⁶O_g.s., ⁶Li_3.56 + ¹⁶O_g.s.). The angular distributions involving ¹⁶O_g.s. show pronounced diffraction structure. The direct-reaction mechanism appears to involve coupling ³He and t with l = 0 angular momentum to either a singlet or triplet state (1970KL09). The ratio σ_g.s./σ_3.56 = 2.24 ± 0.07 rather than 3 (from the ratios of 2J + 1) but this is accounted for by the Q-value dependence of the cross sections (1970KL09). See also ¹⁶O in (1971AJ02).

47. ¹⁹F(α, ¹⁷O)⁶Li Q_m = -12.341

Angular distributions of ⁶Li ions have been measured at E_α = 28 MeV for ⁶Li_g.s. + ¹⁷O_g.s., ⁶Li_g.s. + ¹⁷O_0.87 and ⁶Li_3.56 + ¹⁷O_g.s. (1971KL1E). See also (1968MI05).