A=5Li (1974AJ01)

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⁵Li (1974AJ01)

(See Energy Level Diagrams for ⁵Li)

GENERAL: See also (1966LA04) and Table 5.5 [Table of Energy Levels] (in PDF or PS) here.

Shell model calculations: (1966FR1B, 1968GO01, 1968GO36, 1970RA1D, 1971RA15, 1972LE1L, 1973HA49).

Cluster calculations: (1965NE1B, 1971HE05).

Special levels: (1970HE1D, 1971HE05, 1971RA15, 1973JO1J).

Electromagnetic transitions:(1973HA49).

General reviews: (1966DE1E).

Special reactions: (1971CH31).

Other topics: (1968GO01, 1970RA1J, 1971CH50, 1971ZA1D, 1972CA37, 1972HA57, 1972JA14, 1972LE1L, 1973RO1R).

1. ³He(d, γ)⁵Li Q_m = 16.39

Excitation curves and angular distributions have been measured for E_d = 0.2 to 2.85 MeV (1954BL89), E_d = 0.2 to 1.2 MeV (1968BU09), E_d = 1 to 5 and E(³He) = 2 to 5.5 MeV (1968KR03), E(³He) = 2 to 26 MeV (1972KI01), E(³He) = 2.3 to 11.2 MeV (1968DE14) and E(³He) = 3.7 to 12 MeV (1970SC18).

A broad maximum in the cross section is observed at E_d = 0.45 ± 0.04 MeV [⁵Li*(16.66)]: σ = 50 ± 10 μb, Γ_γ = 11 ± 2 eV (1954BU06: γ₀ + γ₁); σ_γ₀ = 21 ± 4 μb, Γ_γ₀ = 5 ± 1 eV (1968BU09). See also (1968KR03). The radiation at resonance is isotropic, consistent with s-wave capture: see (1954BU06, 1968BU09, 1968KR03). Study of γ₀ and γ₁ yield Γ = 2.6 ± 0.4 MeV for the ground state width, and E_x = 7.5 ± 1.0 MeV, Γ = 6.6 ± 1.2 MeV for the 1/2^- state. The ratio of γ₀ to γ₁ is 1.00 ± 0.2 and 1.9 ± 0.4 at E_d = 480 and 1025 keV (1968BU09).

An excess in the cross section at higher bombarding energies is interpreted by (1972KI01) as being due to a state at E_x ≈ 18 MeV: even parity is deduced from the relative intensity of γ₀ and γ₁. It is presumed to be the 1/2⁺ state reported in reactions 3 and 7. A broad peak is also observed at E_x ≈ 20.7 MeV in the γ₀ cross section. The cross section for γ₁ is ≈ 0. The observations are consistent with J^π = 5/2⁺: angular distributions appear to require at least one other state with significant strength near 19 MeV (1972KI01). (1970SC18) also report this state but find E_x = 19.7 ± 0.2 MeV [Γ = 5.0 MeV]: (2J + 1) Γ_γ₀ = 1.32 keV (± 50%), suggesting E1 (if only one state is involved). See also (1971WA08; theor.).

2. ³He(d, n)⁴Li Q_m = -5.324

This reaction has not been observed: see (1966LA04) and reaction 7 in ⁴Li in (1968ME03).

3. (a) ³He(d, p)⁴He Q_m = 18.3538 E_b = 16.39
(b) ³He(d, np)³He Q_m = -2.22464
(c) ³He(d, 2p)³H Q_m = -1.4608
(d) ³He(d, 2d)¹H Q_m = -5.4938

Below 100 keV the cross section follows the simple Gamow form: σ = (18.2 ± 10³/E)exp(-91E^-1/2) b (E in keV) (1953JA1A, 1954AR02). The zero-energy cross section factor S₀ = 6700 keV · b (1964PA1A). A pronounced resonance occurs at E_d = 430 keV, Γ ≈ 450 keV. The peak cross section is given as 695 ± 14 mb (1952BO68, 1955KU03): see Table 5.2 (in PDF or PS). See also (1970CA1K, 1972PL02). Excitation functions for gorund state protons have also been reported by (1966WA18: E(³He) = 0.39 to 1.46 MeV), (1971GR47: E_d = 2.8 to 11.5 MeV), (1972BA30: E_d = 9.4 to 17.8 MeV) and (1972KI02: E(³He) = 18.7 to 44.1 MeV). Angular distribution and polarization measurements are summarized in Table 5.6 (in PDF or PS). Below E_d = 1.1 MeV, the polarization analyzing power of the reaction is minimally affected by p-wave contributions (less than a few percent). However, at E_d = 500 keV, the analyzing power is reduced by 12 ± 5% by intervention of the s-wave J^π = 1/2⁺ channel (1966BR02, 1967MC01, 1971LE27). See also (1971RO35, 1972SI1F, 1973OH02). (1971LE13) have evaluated matrix elements for l = 1 at E_d = 0.43 MeV. Vector polarization effects at E_d > 1 MeV disagree with the predictions of stripping theory (1966BR02). See also (1971ZA1C). Contour maps, T_ab vs. θ, E_d for the vector and tensor analyzing powers are presented for E_d = 0 to 12 MeV by (1971GR47). See also (1971KL02, 1973CL13). Energy dependence of the angular distributions indicate resonance-like behavior at E_x = 16.6, 17.5, 20.0, 20.9 and 22.4 MeV in ⁵Li (1971GR47). See also (1972SE09, 1973CL13). At E_d ≈ 6 MeV (1971KL02) find the angular distribution more complex than could be accounted for by a single ²D_3/2 or ²D_5/2 level at E_x ≈ 20 MeV [see ³He(d, d)]. For E_d(cm) = 7 to 18 MeV, differential cross sections fall monotonically with no indication of states of ⁵Li with 23.4 < E_x < 34, with Γ > 0.8 MeV and with appreciable widths for decay into ³He + d (1972KI02). See also (1972BA30). The analyzing power for ³He polarization has been studied by (1971HA02, 1971HU1B, 1971LE13, 1971LE27): see (1971ST1J). For a discussion of excitation of ⁴He excited states in reaction (a) see (1973FI04).

Reaction (b) has been studied at E_d = 10.92 MeV (1972NI02), 11.0 MeV (1970LA10, 1970LA1K), E(³He) = 16.5 MeV (1971LI04), 18 MeV (1965ZU02), 18.0 and 24.0 MeV (1970AS02), E(³He) = 27 MeV (1971WA18, 1973WA13) and E_d = 27.5 MeV (1973CH05). See also (1966LA04). The spectra show the influence of neutron-proton final state interaction. Sequential decay via excited states of ⁴He is also reported: see (1970AS02, 1972NI02) and (1973FI04).

Reaction (c) has been investigated at E_d = 10.9 MeV (1972NI02), 11 MeV (1965TO01, 1970LA10, 1970LA1K), 15.2 and 20.2 MeV (1967NE1B, 1968NE1D), E(³He) = 16.5 MeV (1971LI04), 18 MeV (1965ZU02), 18.0 and 24.0 MeV (1970AS02), 19.9 MeV (1971GR12), E_d = 20.7 MeV (1970WA15), 24 to 33 MeV (1963BI14, 1964CO1A), 29.8 MeV (1970SL1A), E(³He) = 27 MeV (1971WA18, 1973WA13), 30 MeV (1973TR1H), E_d = 39.1 MeV (1971RU07, 1971RU1E), E_d = 36 MeV and E(³He) = 53 MeV (1967MO08, 1967MO1E, 1968MO10) and at E_d = 83 MeV (1972BA32). See also (1972SC1R, 1973SL03). The triton spectra are characterized by p-p final state interaction and by sequential decay via ⁴He*, as in reaction (b). (1970LA10, 1970LA1K) have analyzed the data of (1968MO10) using all first order interactions, in PWBA. The calculations indicate that complex exchange processes cannot be ignored, and that estimates of the nucleon-nucleon scattering length from such experiments are highly ambiguous (1970LA10, 1970LA1K).

Under kinematic conditions such that two outgoing particles have small relative kinetic energy, a DWBA analysis with two-body interactions has some success in accounting for spectral shapes: see (1967HE1B, 1971CH31, 1971WA18, 1972WA22, 1973WA13, 1973SL03). Reaction (d) has been studied at E(³He) = 26.8 MeV (1972WA22).

4. ³He(d, d)³He E_b = 16.39

In the range E_d = 380 to 570 keV, the scattering cross section is consistent with s-wave formation of the J^π = 3/2⁺ state at 16.66 MeV (1954BR05). The excitation curves for E_d = 1.96 to 10.99 MeV show a broad resonance (Γ > 1 MeV) corresponding to E_x = 20.0 ± 0.5 MeV. From the behavior of the angular distributions an assignment of ²D_3/2 or (²D, ⁴D)_5/2 is favored, if only one state is involved [see, however, ⁷Li(p, t)⁵Li] (1967TO02). [There is some evidence that there is more than one D-wave state in this E_x region: see reaction 3]. See also (1969DA1F, 1972AL1P). In the range E_d(cm) = 7 to 18 MeV differential cross sections show only a monotonic variation with energy. There is no evidence for any other resonances from E_x = 23 to 34 MeV (1972BA30, 1972KI02). See also (1970WI1G). Angular distributions have been measured at a number of energies from E(³He) = 18.7 to 44.1 MeV (1972KI02). Polarization measurements are reported for E_d = 4.0 to 11.5 MeV (1972KO07), 4 to 12 MeV (1973BA2P), 4.78 to 11.88 MeV (1970HA1M, 1971HA02), 5.7, 7.1, 8.4 and 9.4 MeV (1973LO1D), 6, 8 and 10 MeV (1969PL01), 9.9 and 11.9 MeV (1970WA32) and 10 and 12 MeV (1971DO1C). Strong variations of the angular distributions for all components of the analyzing power are observed between E_d = 4.0 and 8.0 MeV: it is suggested that one or more positive parity states are involved (18.8 < E_x < 21.2 MeV). At higher energies potential scattering is the dominant mode (1972KO07). See also (1971BA1U, 1971ST1J) and (1966BA1J, 1966BA1M, 1967HE1B, 1970BR1L, 1970HE1D, 1971HA1L, 1972TA1E, 1973CH27, 1974CH02; theor.).

5. (a) ³He(t, n)⁵Li Q_m = 10.13
(b) ³He(t, np)⁴He Q_m = 12.0963

For reaction (a) see (1966LA04) and (1971KL04). For reaction (b) see (1970GR17) and ⁶Li.

6. (a) ³He(³He, p)⁵Li Q_m = 10.89
(b) ³He(³He, 2p)⁴He Q_m = 12.8601
(c) ³He(³He, 3p)³H Q_m = -6.9546

The spectrum of protons shows a pronounced peak corresponding to ⁵Li_g.s. superposed on a continuum (1965BA1D, 1965BA1E, 1972DE46: E(³He) = 3 to 18 MeV): the ⁵Li breaks up with a strong angular asymmetry (1968BA1N). The α-spectra E(³He) = 6.9, 7.9, 9.1 MeV) have been analyzed in terms of final state interactions including both p-p and p-α interactions (1972DE46). At E(³He) = 43.7 and 53.0 MeV, the spectra show a prominent peak at the high energy end whose angular distributions exhibit a pronounced diffraction pattern (1967SL01, 1968MO10). See also (1965ZU02, 1966BL02, 1966WA18, 1967MO1E, 1968BL06) and (1973LI1M; theor.). A search for a three-proton enhancement (reaction (c)) was unsuccessful at E(³He) = 44 MeV (1968TO01) and 53 MeV (1968MO10). See also (1966LA04).

7. ⁴He(p, p)⁴He E_b = -1.97

Differential cross sections and polarizations have been measured at many energies: see Table 5.5 (in PDF or PS) in (1966LA04) and Table 5.7 (in PDF or PS) here.

Phase shifts below E_p = 3.2 MeV have been determined by (1967BR03) based on polarization measurements of (1967BR02) and available differential cross sections. The results are in essential agreement with earlier phase shifts of (1949CR1A) but are considerably more precise. In this range, the s-wave phase shift is that of a hard sphere with R = 2.48 fm; d-wave shifts are zero. The P_3/2 phase shift shows a pronounced resonance corresponding to ⁵Li_g.s. while the P_1/2 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: see (1959AJ76, 1966LA04) for reviews of earlier results.

From E_p = 3 to 18 MeV (1971SC04) have analyzed available polarization and differential cross section data to produce a set of phase shifts constrained to an analytic (effective range expansion) energy dependence. d- and f-wave phase shifts are positive and become of some importance above 8 MeV. A polarization contour plot is presented for E_p = 1 to 18 MeV (1971SC04). See also (1968MO26, 1971AR20, 1973AR1N). An R-matrix (single level plus background) formalism is used by (1972ST01). For P_1/2 and P_3/2 the resonance energies are given by E_R = 8.10 and 2.06 MeV and the reduced widths γ² = 12.30 and 8.02 MeV, respectively (1972ST01). See also (1973NI1B).

A resonance is observed at E_p = 23 MeV, corresponding to the known 3/2⁺ state at E_x = 16.7 MeV (1968AL1B, 1968DA04). An anomaly in the polarization is also observed at this energy (1966WE03, 1968DA04, 1972BA24). A further broad feature in the polarization excitation function (θ = 102°) is observed at E_p = 30 MeV (E_x = 22 MeV) (1972BA24). Cross sections for 23 < E_p < 45 MeV show no further evidence of excited states (1969BU10).

An extensive phase shift analysis, using complex phases with l ≤ 4 over a range E_p = 20 to 40 MeV was made by (1972PL02), using mainly polarization and differential cross section data of (1972BA24). The D_3/2 level is fit with R-matrix formalism, including background interference, with the following parameters: E_x = 16.68 MeV, γ²_p = 122 keV, γ²_d(l = 0) = 1.58 MeV (negative sign), γ²_d(l = 2) = 1.58 MeV, θ²_p = 0.014, θ²_d = 0.765.

The E_p = 30 MeV structure is not reflected in anomalous behavior of any single phase shift. Strong absorption of even partial waves may indicate broad overlapping positive-parity levels, J^π = 1/2⁺, 3/2⁺, 5/2⁺, 7/2⁺ of d+³He character near E_x = 22 MeV, but there is no umambiguous identification of excited states other than the 3/2⁺ state in the p-α results (1972PL02). In an alaysis of data of (1971PL07) for E_p = 25 to 29 MeV, (1971RA27) report evidence for a 5/2⁺ level at E_x = 20 MeV [Γ_el/Γ_total = 0.15, Γ_tot = 8 MeV] and a 1/2⁺ level at E_x = 18 ± 1 MeV.

Other phase-shift analyses are reported by (1971AR20, 1973AR1N: 0 to 23 MeV), (1972ST01: 0.3 to 20 MeV), (1967BR02, 1967BR03: 0.9 to 3.2 MeV), (1966WE03: 14.3 to 31.0 MeV), (1967DA08: 29, 40, 48 MeV) and (1969PE01: 63, 70, 80 and 94 MeV). See also (1968PL02, 1973AR1P, 1973HO1U).

Elastic scattering at E_p = 587 MeV (1972BO29) and at 1 GeV (1967PA25) reflect the mass distribution and multibody correlations within the α-particle.

Alpha-proton bremsstrahlung is observed at E_p = 7.0 to 12.0 MeV (1971WO07, 1972WO1E), and at E_α = 20 MeV (1967BO1B). See also (1972AN1P). Cross section measurements have also been carried out at E_p = 23.4 to 48.5 MeV (1973DA1N, 1973DA1P), 180 to 560 MeV (1972SC1M) and at 1 GeV (1967IG1A). For inelastic scattering to excited states of ⁴He, see (1973FI04). For pion production, see (1972GU1D).

8. (a) ⁴He(p, d)³He Q_m = -18.3538 E_b = -1.97
(b) ⁴He(p, pn)³He Q_m = -20.5785
(c) ⁴He(p, 2p)³H Q_m = -19.8147

Angular distributions of ³He ions (reaction (a)) have been measured at E_p = 27.9 MeV (1957WI22), 31 MeV (1953BE14, 1964BU16), 46.8 MeV (1969RO1L, 1969RO24), 49.5 MeV (1969HA16, 1970HA36), 53 MeV (1964CA1B), 55 MeV (1964HA13, 1964HA1P, 1964HA49), 94 MeV (1958SE74) and 155.4 MeV (1967BE35, 1970BE49). See also (1973VO1M). The excitation function shows no indication of resonances for E_p = 38.5 to 44.6 MeV (1969BU10). Polarization measurements have been carried out at E_p = 32, 40, 50 and 52.5 MeV (1973SA1W) and 55 and 63 MeV (1966BO1A). At E_p = 141 MeV the total reaction cross section (not including elastic scattering) is 79.5 ± 2.0 mb (1972NI04).

Reactions (b) and (c) have been studied at E_p = 46.8 MeV (1969RO1L, 1969RO24, 1970RO17, 1970SA01), 49.5 MeV (1969HA16, 1970HA36) and 156 MeV (1967BE35, 1970BE49). See also (1973KI1L, 1973RO1Z). Angular distributions have been measured in the region of the final state interactions. The t and ³He spectra show peaks due to sequential reaction processes via continuum resonance states in ⁴He: see (1973FI04). See also (1967AU1A, 1968PA1J) and (1969DO1G, 1969NA1F, 1973HA46, 1973JU02; theor.). For ⁴He(p, 2N + χπ) see (1965KU1C).

9. (a) ⁴He(d, n)⁵Li Q_m = -4.19
(b) ⁴He(d, np)⁴He Q_m = -2.22464

Reaction (b) has been studied at E_d = 14.2 MeV (1967FU1D), E_α = 29.2 MeV (1968TA11), 38.8 MeV (1971LE02), 42 MeV (1967WA08, 1968WA01) and at E_α = 18.0 and 24.0 MeV (1970AS02). See also (1971CH1T). The data indicate that at 42 MeV, direct breakup, with quasi-free α - p scattering taking place and the n acting as a spectator, is at least as important a mechanism as the final state interaction in the ⁵Li ground state (1967WA08, 1968WA01): see ⁵He. See also (1967NA1D, 1969NA09, 1972NA1D; theor.) and (1966LA04) for the earlier references.

10. ⁴He(³He, np)⁵Li Q_m = -9.68

See (1973HA50).

11. ⁶Li(γ, n)⁵Li Q_m = -5.66

See ⁶Li and (1965BA16).

12. (a) ⁶Li(p, d)⁵Li Q_m = -3.44
(b) ⁶Li(p, pd)⁴He Q_m = -1.4737

Deuteron groups are observed to ⁵Li*(0, 16.7). Angular distributions have been measured at E_p = 18.6 MeV (1955LI09; d₀), 33.6 MeV (1967KU10, 1970KU1D; d₀, d₂), 100 MeV (1969LI02; d₀) and 156 MeV (1968BE72, 1969BA05, 1969TO1A; d₀, d₂). See (1969TO1A) for spectroscopic factors. In addition, the excitation of a state with E_x = 3.72 ± 0.10, Γ = 6.3 ± 0.5 MeV is reported by (1966SE1C). [See, however, (1967KU10, 1970KU1D)]. (1969BA05) confirm the population of the first excited state. See also (1966SE1C, 1972AZ03) and (1968JA1D; theor.).

At E_p = 9 and 10 MeV (1968VA02) and at E_p = 45 MeV (1971BR12), the p-α final state interaction corresponding to ⁵Li(0) is observed.

13. (a) ⁶Li(d, t)⁵Li Q_m = 0.59
(b) ⁶Li(d, pt)⁴He Q_m = 2.5592

Angular distributions of the tritons to the ground state of ⁵Li have been measured at E_d = 15 and 20 MeV (1959VL24, 1960HA14). See also (1971IN1C). For reaction (b) see (1968LE15).

14. (a) ⁶Li(³He, α)⁵Li Q_m = 14.91
(b) ⁶Li(³He, pα)⁴He Q_m = 16.880

At E(³He) = 25.5 MeV, the spectra show ⁵Li*(0, 16.7) and two broad peaks at E_x ≈ 19.8 and 22.7 MeV with Γ_cm = 2 and 1 MeV, respectively (1972BA30).

Cylindrical asymmetry observed in the breakup of ⁵Li(0) is attributed to the short lifetime of the ⁵Li imtermediate state and to the memory retained by the proton of its localization at the time of formation of ⁵Li (1967RE03, 1968RE10). The first excited state of ⁵Li also appears to be involved (1972TH08, 1972TH1B). See also (1964MA57, 1966LO10, 1967HO1C, 1968VI03, 1969VI05, 1970GA1G), (1966LA04), (1970DE41, 1972TH04; theor.) and ⁸Be.

15. (a) ⁷Li(p, t)⁵Li Q_m = -4.43
(b) ⁷Li(p, pα)³H Q_m = -2.467

At E_p = 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 for a very broad excited state between E_x = 2 and 5 MeV. ⁵Li*(16.7, 20.0) were not observed. The formation of ⁵Li*(16.7) (⁴S_3/2) would be S-forbidden: the absence of ⁵Li*(20.0) would indicate that this state(s) is also of quartet character [see reaction 19 in ⁵He] (1966CE05). See also (1966BA1L, 1967PO1C). Weak, broad states at E_x = 22.0 ± 0.5 MeV and 25.0 ± 0.5 MeV and possibly 34 MeV are reported by (1968MC02) in a coincidence experiment in which 3- and 4-particle breakup was analyzed. The t₀ angular distribution has also been studied at E_p = 16.6 MeV (1965OG03) and 30.3 MeV (1969DE04).

For reaction (b) see (1967JO1C).

16. ¹⁰B(³He, pα)⁴He⁴He Q_m = 12.420

At E(³He) = 2.45 and 6.00 MeV the reaction proceeds in part via the first two states of ⁵Li (1966WA16).

17. ¹²C(p, 2α)⁵Li Q_m = -9.24

Not observed: see (1972MA62).