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GENERAL: See (1958BL57, 1959BA1D, 1959BR1E, 1959PI45, 1959TH16, 1960HE04, 1960KU1B, 1960PH1A, 1960SP08, 1960TA1C, 1960VA1H, 1961BA1G, 1961BA1E, 1961CL10, 1961GU1B, 1961KU1C, 1962BA1C, 1962IN02, 1962SC12, 1962TA1H, 1963HI1B, 1963MA1E, 1963SC1P, 1964AM1D, 1964BA29, 1964BA1Y, 1964BE1M, 1964GR1J, 1964NE1E, 1964RE1C, 1964ST1B, 1965BO1M, 1965KU1E, 1965MU1A, 1965NE1C, 1965RO1H, 1965WO01).

See also Table 9.2 [Table of Energy Levels] (in PDF or PS).

Ground state: μ = -1.1776 nm; Q = ± 0.03 b (1965FU1G).

1. (a) 6Li(t, d)7Li	Qm = 0.995	Eb = 17.688
(b) 6Li(t, p)8Li	Qm = 0.803
(c) 6Li(t, n)8Be	Qm = 16.023
(d) 6Li(t, α)5He	Qm = 15.160

The differential cross section for reaction (a) at 90° measured up to E_t = 1.90 MeV increases rapidly with energy below the coulomb barrier and then approaches a constant value. At 1.50 MeV, the total cross section for formation of the ground state of ⁷Li is 190 mb; that for the first excited state is 4 times less (1961HO21: see also (1957JA37)). Angular distributions for both groups show maxima in the forward hemisphere. It is suggested that the large cross section indicates a cluster exchange process - here the exchange of t and d (1961HO1F, 1961HO21).

The 0° differential cross section for reaction (c) increases monotonically between 0.10 and 2.4 MeV (1960SE12, 1961VA43, 1962SE1A) except for a resonance at E_t = 1.875 MeV, corresponding to an excited state of ⁹Be at 18.937 MeV. The total cross section for neutron production at E_t = 2.12 MeV is 324 ± 32 mb (1961VA43). See also (1963JA1E).

The 90° differential cross section for reaction (d) rises from 0.75 mb/sr at 0.62 MeV to 5.7 mb/sr at 1.8 MeV and then decreases slowly to 5.3 mb/sr at 2.2 MeV (see (1957JA37)). See also ⁵He, ⁷Li, ⁸Li and ⁸Be.

2. 6Li(α, p)9Be	Qm = -2.126
	Q0 = -2.1256 ± 0.012 (1965BR28).

Angular distributions of ground-state protons have been measured at E_α = 10.15, 11.5 and 13.5 MeV (1960MA15) 13.6 and 14.7 MeV (1962KO13) and 30 MeV (1960KL03). At 30 MeV, strong backward peaking is evident (1960KL03). A qualitative account of the observations can be given if heavy-particle stripping (p + ⁵He + α) is assumed (1962HO1C). See also (1956WA29).

3. 6Li(6Li, 3He)9Be

Qm = 1.895

See (1964KI02).

4. 7Li(d, γ)9Be

Qm = 16.693

In the region E_d = 0.1 to 1.1 MeV, a resonance in the yield of capture γ-rays is observed at E_d = 362 ± 3 keV (1965WO01), 361 ± 2 keV (1965IM01), corresponding to an excited state in ⁹Be at 16.973 ± 0.002 MeV. The width of the level is less than 470 eV (c.m.). The small width of the level and the correspondence with ⁹Li*(2.69) argues for T = 3/2 (1965WO01). The angular distribution of the γ-rays to the ground state is isotropic to within 7%. The branching ratios to the ground state, and to the levels at 1.67, 2.43, 3.03 and 4.70 MeV are 100/8.5 ± 4.3/10.6 ± 5.3/ ≤ 4.5/9.6 ± 4.8. An upper limit for non-resonant, direct capture is 1.6 μb. The neutron decay of ⁹Be*(2.43) and ⁹Be*(4.70) is observed (1965IM01).

5. (a) 7Li(d, n)8Be	Qm = 15.028	Eb = 16.693
(b) 7Li(d, α)5He	Qm = 14.165
(c) 7Li(d, n)4He + 4He	Qm = 15.122

The cross sections for reactions (a) and (b) have been measured for E_d = 70 to 110 keV (1955RA14), 30 to 250 keV (1953SA1A) and 330 to 400 keV (1965IM01). The 0.36 MeV resonance is observed here also, in the yield of neutrons with E_n > 10 MeV: the ratio of the partial width of the 16.97 MeV level for emission of neutrons to ⁸Be_g.s. to that for emission of γ-rays is ≈ 1.5, while Γ_α0/Γ_γ < 20 (1965IM01).

The yield of neutrons has been measured from 0.2 to 4.8 MeV by (1952BA1A, 1957SL01: see also (1947BE1A, 1949WH1A)), and the yield of α-particles has been measured from E_d = 0.2 to 0.3 MeV by (1964MA60) and for 0.7 to 3.0 MeV by (1963PA04). Resonances for neutron production are observed at E_d = 0.68, 0.98 and (1.8) MeV (Table 9.4 (in PDF or PS)). At E_d = 0.90 MeV, α-particles from reaction (b) are isotropic within 2%, consistent with formation by s-wave deuterons (1957RI39). The angular correlation of ground-state α-particles with those resulting from the breakup of ⁵He indicates J = 5/2^- for the ⁹Be level mainly responsible for the reaction at E_d = 0.9 MeV (1956RI37); a similar observation at E_d = 0.16 MeV suggests J = 3/2^- for the responsible level (1957FA10). See also (1964FE01). At E_d = 0.9 MeV, reactions (a) and (c) account for less than 10% of the disintegrations at this energy (1956RI37). Polarization of ground-state neutrons has been measured by (1962HE06).

The excitation function for reaction (b) shows indications of the E_d = 0.7 and 1.0 MeV resonances (unresolved in this work) as well as broad structure at E_d = 2.5 MeV. There is no indication of resonance at 1.8 MeV in this ground-state α-yield. Also reported are α-particles from reaction (a) associated with the ⁸Be excited states at 11.3, 16.6 and 16.9 MeV; the α-particles from the decay of the 11.3 MeV state seem to show resonance behavior at E_d = 0.7, 1.0 and 1.75 MeV. It is not clear whether the α-particles corresponding to ⁸Be*(16.6) show resonance at E_d = 2.5 MeV or whether the ⁸Be*(16.9) α-particles are appearing at this point (1963PA04). See also (1964BI10, 1965BI1F, 1965JO19), ⁵He and ⁸Be.

6. 7Li(d, p)8Li

Qm = -0.192

Eb = 16.693

The yield of ⁸Li (ground-state protons) has been measured for E_d = 0.29 to 0.78 MeV. A resonance is observed at E_d = 360 ± 3 keV with Γ < 2 keV. The ratio Γ_p/Γ_γ is ≈ 0.5 (1965IM01, 1965WO01): see also ⁷Li(d, γ)⁹Be.

The yield of ⁸Li(p₀ + p₁) has been measured in the range E_d = 0.4 to 3.3 MeV by (1952BA1A, 1954BA46, 1960KA05) and from 1.1 to 4 MeV by (1956BE1A: stacked foils). Ground-state protons have been examined from E_d = 1.0 to 4.0 MeV by (1960SE08, 1963SE1F). Resonances are reported at 0.77, 1.02, (1.375), 2.0, 2.5 and 3.7 MeV (Table 9.4 (in PDF or PS)), apparently superposed on a rising background. The total cross section at E_d = 0.77 MeV is 150 ± 35 mb (1954BA46), 176 ± 15 mb (1960KA05), From E_d = 1.0 to 4.0 MeV, angular distributions are unusually well described by stripping theory; the resonance at E_d = 1.375 MeV shows no effect on the angular distribution (1960SE08, 1963SE1F).

The yield of 0.95 MeV γ-rays from ⁷Li(d, p)⁸Li* rises smoothly from E_d = 1.9 to 3.3 MeV. Above E_d = 2.3 MeV, the isotropy of the γ-rays is taken to indicate predominance of the stripping process (1962CH14).

7. 7Li(d, d)7Li

Eb = 16.693

The upper limit for the relative partial width for elastic scattering at E_d = 0.36 MeV (⁹Be* = 16.97), Γ_d0/Γ_γ, is 400 (1965IM01).

The elastic scattering has been studied from E_d = 0.4 to 1.8 MeV by (1964FO13). The scattering cross sections lie below the Rutherford values at the lower energies. A marked increase occurs in the range E_d = 0.8 to 1.0 MeV, and a conspicuous anomaly occurs at E_d = 1.0 MeV. A rising background is ascribed to other overlapping resonances. The scattering below E_d = 1.0 MeV can be satisfactorily accounted for by s-waves: the variation of parameters is consistent with - but does not require - a level at E_d = 0.8 MeV. The resonance at 1 MeV appears to be due to p-wave deuterons (1964FO13). See also ⁷Li and (1958RO49).

8. (a) 7Li(d, t)6Li	Qm = -0.995	Eb = 16.693
(b) 7Li(d, 3He)6He	Qm = -4.486

The cross section for reaction (a) rises steeply from threshold to 95 mb at E_d = 2.4 MeV and then more slowly to about 165 mb at E_d = 4.1 MeV (1955MA20). See also ⁶He and ⁶Li.

9. 7Li(t, n)9Be

Qm = 10.435

See (1959AJ77, 1962SE1A) and ¹⁰Be.

10. 7Li(3He, p)9Be

Qm = 11.199

Observed proton groups are listed in Table 9.5 (in PDF or PS) (1955AL57, 1958MO99, 1963CA02, 1965CO1F, 1965MA1E). The γ-decay of the narrow 14.39 MeV state to the ground and 2.4 MeV states indicates Γ_γ0/Γ_p = 0.023 ± 0.005, Γ_γ1/Γ_p = 0.04 ± 0.01. Assuming Γ_γ0 = 18 eV (see ⁹Be(e, e')), Γ = 0.8 ± 0.3 keV for the 14.39 MeV state. This level is presumed to be the lowest T = 3/2 state of ⁹Be, analogous to the ⁹Li ground state (1965GR08, 1965LY01). There is some evidence also for the γ-decay of a state at ≈ 17 MeV, presumably the T = 3/2 analogue of the first excited state of ⁹Li (1965GR08: see also ⁷Li(d, γ)). See also (1961WO05) and ¹⁰B.

11. 7Li(α, d)9Be

Qm = -7.154

The ground-state angular distribution has been observed at E_α = 48 MeV (1960CE01). See also (1962MA59).

12. 7Li(6Li, α)9Be

Qm = 15.220

At E(⁷Li) = 2.9 MeV, α-particle groups are observed corresponding to ⁹Be*(0, 1.75, 2.4, 3.0, 11.9 ± 0.2 MeV); the last has Γ = 500 ± 100 keV. No other levels are observed for E_x < 13.0 MeV (1964ME07). See also (1963GA02, 1963HU02, 1964KI02, 1965BE1X).

13. 9Li(β-)9Be

Qm = 13.615

⁹Li decays to the ground state (25 ± 15 %) and to ⁹Be*(2.4) (75 ± 15 %): log ft = 5.5 ± 0.2 and 4.7 ± 0.2, respectively. The allowed character of the transition is consistent with ⁹Be*(2.4) = 5/2^- and ⁹Li(0) = 3/2^- or 5/2^- (1963AL18). See also ⁹Li.

14. 9Be(γ, γ)9Be

See (1964LO1C).

15. (a) 9Be(γ, n)8Be	Qm = -1.665
(b) 9Be(γ, α)5He	Qm = -2.528
(c) 9Be(γ, n)4He + 4He	Qm = -1.570
(d) 9Be(γ, 2n)7Be	Qm = -20.561

The photoneutron cross section has been measured from threshold (E_γ = 1664 ± 4 keV: (1956CO56)) to 320 MeV: see Table 9.6 (in PDF or PS). A sharp peak occurs just above threshold, at E_γ = 1.70 MeV (1960WA06, 1961JA13) followed by a weak maximum at 2.4 MeV, a strong sharp peak at 2.95 MeV, and a broad maximum at 4.6 MeV (1961JA13). (1959TH15) find well-defined peaks at 11.3 ± 0.2 and 13.3 ± 0.2 MeV, with integrated cross sections of 4.0 and 3.9 MeV · mb. A considerable yield in the range 8 - 11 MeV is also indicated (1959TH16). The giant resonance occurs at 20 - 22 MeV (1953JO1B, 1953NA1A, 1956CO59). At E_γ = 6.1 MeV, the main processes appear to involve ⁹Be(γ, n)⁸Be*(2.9) and reaction (b) (1954CA1A). For E_γ = 18 to 25 MeV, ≈ 80% of (γ, n) processes lead to ⁸Be*(16.6) (1964BE30). See also (1960SE1D, 1965KO08, 1965KO1B).

The total nuclear absorption cross section is about 2 mb at E_γ = 10 MeV: a deep minimum at ≈ 13 MeV is followed by a rise to ≈ 5 mb at 18 MeV and a slow decrease to ≈ 3 mb at 35 MeV (1965WY02). Fine structure is reported at E_γ = 20.47 ± 0.04 and 20.73 ± 0.04 MeV (1964TE04). See also (1962MI15).

Measurements involving time-of-flight analysis of the neutron energies show the 1.7 and 3 MeV resonances in ground-state neutrons (n₀), but ascribe the 4.6 MeV structure to slow neutrons, arising from reactions (b), (c) or from n₁ to ⁸Be*(2.9): ground-state neutrons account for < 10% of the total at this energy. The yield of n₀ remains essentially constant from 5 to 16 MeV, aside from a broad maximum near 10 MeV and a shallow minimum at 13 MeV. The yield of n₁ rises sharply near 6 MeV, showing signs of a sharp peak at 7 MeV and remains high until about 10 MeV where it falls rapidly to a minimum at 13 - 14 MeV. There is evidence of a broad peak near 12 MeV (1963DE1J). For E_γ = 5.6 to 8.5 MeV, the relative contribution of n₀ ranges from 0.5 to 0.3 (1963BO32).

Angular distributions of neutrons from the 1.67 and 4.6 MeV levels are isotropic; those from the 2.4 MeV level show slightly higher yield at θ = 90°. Neutrons from the 3.0 MeV level have the distribution σ(θ) = 1 + (1.0 ± 0.2)sin²θ, compatible with E1 excitation to a 5/2⁺ D-state (1961JA13: see also (1949HA1A, 1961BA1G)). Some fore and aft asymmetry may indicate the presence of odd-parity amplitudes (1965PH1B). The fact that the 3.0 MeV state is strongly excited in (γ, n) and not in 180° (e, e') (M1 excitation) also indicates positive parity (1961BL1D). The same argument suggests positive parity (E1 transitions) for levels at 1.7, 6.8, 7.9, 9.2, 11.3 and 13.3 MeV (1959TH16). For E_γ = 5.6 to 8.5 MeV, angular distributions are of the form 1 + Asin²θ, with A = 0.20 to 0.27, consistent with P_3/2 → D_3/2 transitions (1962BO08, 1962BO21, 1963BO32). Evidence for polarization of neutrons is reported by (1964CO17). See also (1959KU84, 1961VA09, 1964AL33).

Calculations of the (γ, n) cross section near threshold have been made by (1960FR1B), using a single-particle model with a diffuse-surface Saxon-Woods potential and assuming a 1/2⁺ level at E_x = 1.70 MeV. A good account of the observations is obtained, but with a rather large diffuseness parameter, a = 1.2 fm, in the final state. If the parameter is taken to be a = 0.6 fm, the calculated cross section is about 1.6 times too high. According to (1961BL1D), a model in which the neutron in ⁹Be(0) is strongly coupled to a deformed ⁸Be core leads to a sizable probability of excitation of the core to the 2⁺ state, reducing the calculated cross section at 1.7 MeV. The 4.7 MeV structure is then ascribed to transformations in which ⁸Be is left in the excited 2⁺ state. A calculation of the low-energy excitation function has been made by (1963CO05) using the same model as (1960FR1B) but fixing the final state diffuseness parameter at a = 0.6 fm, and varying the final state potential depth. The slope and magnitude of the observed (γ, n) cross section are best accounted for by a bound s-state, with energy 19⁺⁹_-5 keV below threshold (1963CO05). (1961BA1G) considers couplings of 1s and 1d neutrons to ⁸Be(0) and ⁸Be(2⁺). With the 1.7 MeV level assumed 1/2⁺, 3/2⁺ and 5/2⁺ levels are predicted at 4.88 and 4.05 MeV, respectively. It is suggested that the 3.03 MeV level is an unresolved combination of 1/2^- and 5/2⁺. See also (1961GU1C, 1961KO1J, 1962CU05, 1962KO11, 1963CO1D, 1963SA09, 1964BI1E, 1964FR1C, 1964MA2E, 1965WE1E).

The cross section for reaction (c) is < 1 μb at E_γ = 1.63 MeV (1952AL26, 1952AL30). For reaction (d) see (1957LO1A).

16. (a) 9Be(γ, p)8Li	Qm = -16.885
(b) 9Be(γ, np)7Li	Qm = -18.917

The yield shows structure in the energy region corresponding to the ⁹Be levels at 17 - 19 MeV (1962CL06), followed by the giant resonance at E_γ = 22.2 MeV (1953HA1A: Γ = 4.7 MeV, σ = 2.72 mb), ≈ 23 MeV (1962CL06: σ = 2.64 ± 0.30 mb). The angular and energy distributions of photoprotons in various energy intervals have been studied by (1956CO59, 1956KL19, 1962CH26, 1963KI1C, 1965KO08). At E_brems.(peak) = 335 MeV, the polarization of photoprotons at 45°, 56° and 90° is small and is consistent with zero (1962LI13). See also (1959CH25, 1961MA36, 1962CU05, 1962MI15, 1962VO1D) and (1959AJ76).

17. (a) 9Be(γ, d)7Li	Qm = -16.693
(b) 9Be(γ, t)6Li	Qm = -17.688

The cross section for reaction (a) is appreciable only for γ-energies greater than the sum of the threshold energy and the binding energy of the most weakly bound nucleon in ⁷Li. The main processes involved are then thought to be those in which the emission of deuterons is accompanied by one or more nucleons (1962BA62, 1962CH26, 1962VO1D). See also (1959CH25, 1960SH1D, 1962CU05, 1962MA1F, 1963BA1K, 1964SH1B, 1965KO08) and (1959AJ76).

18. 9Be(e, e)9Be

Elastic scattering of electrons has been studied at E_e = 42, 80, 125, 150, 190 and 300 MeV (1953HO79, 1954MC45, 1959ME24, 1963GO04). Analysis of the 190 and 300 MeV results has been carried out in terms of various models for the charge distribution; the r.m.s. radius is about 2.60 ± 0.2 fm, depending on the model. At large values of momentum transfer, a static spherical distribution seems inadequate and a contribution from the quadrupole distribution may be required (1959ME24). According to (1960WA1J) the 300 MeV data can be matched with a Fermi distribution plus a quadrupole distortion consistent with Q = 0.02 b. See also (1961WA1C, 1963GU1A). Magnetic scattering at θ = 180° gives indication of both M1 and M3 contributions (1965RA1C: see also (1963GO04)).

Inelastic scattering reveals a number of levels from 1.6 to 16.9 MeV (see Table 9.7 (in PDF or PS)). Of these, only the 2.43, (14.7), and (16.9) MeV levels are strong in 180° scattering, where M1 transitions should dominate (1960BA47, 1962BA1D, 1962ED02). Studies of the 2.4 and 6.7 MeV levels at smaller angles reveal strong E2 components; quantitative comparison with form factors and absolute cross sections predicted by the α-rotational model (1960IN1A) indicate J^π = 5/2^- and 7/2^-, respectively, for these two levels. The excitation energies and transition widths are consistent with the assumption that they are members of a K = 3/2^- rotational band based on the ground state. The derived intrinsic g.s. quadrupole moment Q₀ = 0.26 ± 0.01 b is nearly twice that obtained from the spectroscopic value Q₀ = 5 × 0.029 b (1963NG01). In both this work and calculations of (1962KU1C) the rotational α-model shows increasing deviations from experiment for momentum transfer q > 1 fm^-1; the Nilsson model has the same fault, but in opposite sense. An intermediate coupling model with enhanced quadrupole charge distribution is superior (1962KU1C). See also (1961WA1C, 1965RA1D).

Comparison of the inelastic scattering from the 1.6 MeV level at two angles indicates that this level is most probably excited by E1 (1963NG01). The fact that the 1.6, 3.0 and 4.7 MeV levels appear strongly in (γ, n) but not in (e, e') at 180° suggests that these levels are excited by E1 transitions (1962ED02). [The 14.7 MeV level is presumably the T = 3/2, J = (3/2)^- analogue of the ⁹Li ground state; the 16.9 MeV level may correspond to the first excited state.] In the range 17 to 49 MeV, inelastic scattering appears to be largely via E1, E3, M2 to the exclusion of M1, E2, M3 (1962NG02, 1963NG1B, 1964NG1A).

19. (a) 9Be(n, n)9Be
(b) 9Be(n, 2n)8Be	Qm = -1.665

The neutron spectrum observed when ⁹Be is bombarded with 3.7 MeV neutrons exhibits a structure which is consistent with the excitation of the ground states and the levels at 1.7, 2.4 and 3.1 MeV, with subsequent neutron emission from the latter two. It is concluded that the (n, 2n) process at this energy proceeds mainly via discrete states of ⁹Be (1957HU14, 1958WA05). Time-of-flight studies from E_n = 2.6 to 6.0 MeV show that about 1/2 of the inelastic processes involve ⁹Be*(2.43). A continuous distribution may be ascribed either to ⁹Be*(1.7) or to (n, 2n). Examination of the spectra at E_n = 3.5 MeV yields the result that the 2.43 MeV level decays only 12 ± 5 % via ⁸Be_g.s. (1959MA34). At E_n = 14 MeV, evidence is found for the participation of the 6.8 MeV level. A search for an angular correlation between outgoing neutrons yielded a negative result (1963JE05). At E_n = 14 MeV, the cross section for production of ⁹Be*(2.4) is 200 ± 45 mb (1961CO1E), 200 ± 100 mb (1961MY01), 170 ± 30 mb (1958AN32) comparison with σ(n, 2n) = 500 mb (1964ST25) indicates that about 1/3 of the (n, 2n) processes proceed via ⁹Be*(2.4) (1958AN32). Elastic and inelastic neutron angular distributions show forward peaking at E_n = 14 MeV (1958AN32, 1958NA09). See also (1958BE1E, 1959CH1E, 1959SA04, 1959WI41, 1960BA24, 1960BA28, 1960LU1B, 1960MC04, 1963OP1A, 1964BO31, 1964CR1B, 1965LO1K, 1965RO1U) and ¹⁰Be.

20. 9Be(p, p)9Be

Elastic scattering has been studied at E_p = 6 MeV (1963BL20), 5 to 15 MeV (1964BI19), 10 MeV (1956RA32), 6, 8 and 12 MeV (1963TE1B), 12 MeV (1958SU14), 14.5, 20 and 31.5 MeV (1956KI54), 16.6 to 36.6 MeV (1965AR1E), 18.9 MeV (1956DA03), 31 MeV (1953WRZZ, 1954FI35, 1956BE14), 48 MeV (1965WI1H), 142 MeV (1961TA06), 143 MeV (1964ST16), 160 MeV (1965RO1T), 316 MeV (1956CH80) and 725 MeV (1965MC04). All angular distributions show pronounced diffraction maxima characteristic of the optical model. Analysis in terms of the diffuse-surface optical model is discussed by (1957ME21). See also (1956KL55, 1959HI1H, 1959JO43, 1960NE09, 1960NE11, 1960SA28, 1961IS05, 1961JO18, 1961RE03, 1964CR1B, 1964SA1L, 1964VE1A).

Inelastic scattering is observed to states at 1.7, 2.4, 3.1, 4.8, 6.8, 7.9, 11.3 MeV and others: see Table 9.8 (in PDF or PS). The structure at ⁹Be*(1.7) is unsymmetrical, rising abruptly from threshold at Q = -1.669 MeV to a peak within < 14 keV (1962BR09). The width at half-maximum is 175 ± 25 keV (c.m.), indicating dominant s-wave emission of neutrons (1960SP08). According to (1960SP08) the structure does not represent a true state, but results from the spatial localization of the low-energy neutron and ⁸Be after emission of the inelastically scattered proton. Using a specialized density-of-states function, they obtain a good match to the experimental shape in this hypothesis. See also (1963PH1A). On the other hand, (1962BA1C) find an equally good fit with a density-of-states function of Breit-Wigner shape, corresponding to a J^π = 1/2⁺ level at E_x = 1.75 MeV with width γ²₀ = 1.01 MeV (R = 4.35 fm), parameters which also fit the (γ, n) cross section. At E_p = 18.9 MeV, the 1.7 MeV group is not observed; the upper limit to the intensity of the group is < 2% of that to the 2.4 MeV state (1962SC12). See also (1955GO48, 1956BO18, 1958MI1C, 1958SU14, 1964BI19, 1964SC1F, 1965WI1H).

The energy of the 2.4 MeV level is given as 2433 ± 5 (1951BR72), 2434 ± 5 (1956BO18), 2432 ± 4 (1955GO48), 2430 ± 5 keV (1960SP08); the width is ≤ 1 keV (1955GO48), ≤ 3 keV (1960SP08). Angular distributions of protons leading to the 2.4 MeV state are not well matched by plane wave direct interaction calculations (1962SC12). The 12 MeV data suggest l = 0 and 2 (J^π = 1/2^- or 5/2^-) (1958SU14) while the 31 MeV data are best fitted by l = 2 (1956BE14, 1958SU14, 1962SC12). It appears that the relative inelastic cross sections for various levels are largely independent of bombarding energy or particle; in particular, the 2.4 and 6.8 MeV levels are always strong and the 1.7, 3.0 and 4.8 MeV levels always weak. It is suggested that the strong excitation of the former is relative to a collective enhancement of electric multipole transition strengths connecting them to the ground state (1958BL57, 1959PI45, 1962SC12). The excitation energies and inelastic cross sections are consistent with the assumption that they have J^π = 5/2^- and 7/2^-, respectively. On the collective model, they are members of the ground state K = 3/2^- band: the J = 9/2^- member is then expected at 10 - 11 MeV (1958BL57). See also (1964JA03, 1965HA17).

The 3 MeV state has a width 250 ± 50 keV (1960SP08): E_x = 3.03 ± 0.03 MeV (1956BO18), 3.04 ± 0.05 MeV (1960SP08). Comparison of the width with that of the mirror level ⁹B*(2.79) suggests that the level decays either to ⁸Be(0) via d-wave or to ⁸Be(2⁺) via s-wave: J = 3/2⁺, 5/2⁺ (1960SP08). See also (1955GR12, 1958TY46, 1960LU1B, 1961IS05, 1963BA1R, 1963BL20, 1963RU05).

21. 9Be(p, d)8Be

Qm = 0.559

Angular distributions of ground-state deuterons have been studied at E_p = 4.9, 5.5 MeV (1961RE03), 5 to 8 MeV (1951HA1A), 6.8 MeV (1960NE09, 1960NE11), 7 MeV (1964YA1A), 10 MeV (1956RA32), 12 MeV (1958SU14), 16.5 MeV (1956RE04), 22 MeV (1953CO1C), 31 MeV (1956BE14), 95 MeV (1956SE1A) and 155 MeV (1963BA1R, 1963RA01). The distributions in the range E_p = 5 to 31 MeV are substantially identical, contrary to the prediction of the simple Butler theory with fixed cut-off radius (1956GL25). An analysis by (1961RE03) (see Table 9.9 (in PDF or PS)), shows good agreement for the 12 to 31 MeV data with inclusion of a volume interaction, leading to θ²_n = 1.2%. Polarization of the deuterons has been studied at E_p = 3 MeV (1961LA17). See also (1960BA26, 1965MO27).

At E_p = 95 MeV, states of ⁸Be near 16 to 18 MeV are strongly excited (1956SE1A). At E_p = 155 MeV, states at ≈ 16.6 and ≈ 18.9 MeV are excited with 0° differential cross sections of 3.6 and 1.15 mb/sr, respectively (1963BA1R, 1963RA01).

22. 9Be(p, α)6Li

Qm = 2.126

Angular distributions and excitation functions for E_p = 3 to 12 MeV suggest direct interaction. Analysis with DWBA in terms of ⁹Be → ⁶Li + t (l = 1) yields fair agreement for α₀ but not for α₁ (1963BL20). The observed large cross section at back angles suggests that ⁹Be is better described as ⁴He + ⁵He (1963SC1P). See also (1964YA1A, 1965MO27).

23. (a) 9Be(p, 2p)8Li	Qm = -16.885
(b) 9Be(p, pd)7Li	Qm = -16.693
(c) 9Be(p, pα)5He	Qm = -2.528

The summed proton spectrum in reaction (a), observed at E_p = 155 to 450 MeV shows two peaks, with Q = -16.7 ± 0.3 and Q = -25.8 ± 0.4 MeV, corresponding to removal of a p-proton and an s-proton respectively (1958MA1B, 1958TY49, 1961PU1A, 1962GA09, 1962GA23, 1962IN1A, 1963BE1A, 1963BE42, 1963BO1R, 1963RI1B, 1964BA1C, 1964TI02, 1965RI1A, 1966TY01).

At E_p = 155 MeV, p - α correlations (reaction (c)) give evidence for a substructure ⁹Be = ⁵He + ⁴He in a relative s-state with a probability of 7% (1963RU05).

For reaction (b), see ⁷Li.

24. 9Be(d, d)9Be

Elastic scattering has been studied at intermediate energies by (1961BA06, 1962GR14: 7.8 MeV), (1963FR1F: 12.8 MeV), (1961IS04, 1963SA1G: 14.7 to 18.1 MeV), (1964HE01: 15.8 MeV), (1958SU14: 24 MeV), (1962SL03: 27.7 MeV). All show pronounced diffraction patterns. See also (1947GU1A, 1952EL01, 1959ZA01) and ¹¹B.

Inelastic groups are reported to states at 1.7, 2.4, 3.0, 4.8 and 6.8 MeV (1955RA41, 1956GR37, 1958MI1C, 1958SU14). The angular distributions to the 2.4 MeV state have been studied at E_d = 15, 24 and 27.7 MeV (1956HA90, 1958SU14, 1962SL03). Analysis by direct interaction theory yields l = 2, J = 1/2^-, 5/2^- or 7/2^-. See also (1958BL57, 1959BL31, 1960EL09, 1960LU1B).

25. 9Be(d, t)8Be

Qm = 4.592

Comparison of (d, t) and (p, d) pickup cross sections leads to an estimated form factor for the triton of 4 ± 1 fm^-1 (1961RE03); this values is about 4 times larger than that estimated by (1960MA32).

26. 9Be(3He, 3He)9Be

See (1960IG01, 1962WE1C, 1964GO1J).

27. 9Be(3He, α)8Be

Qm = 18.913

See ⁸Be.

28. (a) 9Be(α, α)9Be
(b) 9Be(α, 2α)5He	Qm = -2.528

Elastic scattering has been studied at E_α = 9.5 to 20 MeV (1965TA1C), 18.4 MeV (1964LU02), 23.8 MeV (1964GR39), 28 MeV (1964YA1A), 42 MeV (1956FA02: see (1958BL57)) and 48 MeV (1958SU14). Inelastic groups are observed to ⁹Be*(1.8, 2.4, 3.0, 6.8, 11.3) (1955RA41, 1958SU14, 1964LU02, 1964YA1A). The angular distribution of the groups corresponding to the 1.8 MeV "level" is consistent with J^π = 1/2⁺ (1964LU02). The angular distribution of the Q = -2.4 MeV group, at E_α = 48 MeV, indicates l = 2, J = 1/2^-, 5/2^- or 7/2^- (1958SU14). Analysis based on the rotational model leads to a deformation coefficient β₂ = 0.46 (1959BL31), 0.34 ± 0.01 (1964GR39).

Measurement of the momentum and angular distributions of α-particles from the breakup of ⁹Be*(2.4) indicates that the decay proceeds mainly via ⁴He + ⁵He, or by direct three-body breakup. Gamma decay is < 1%, neutron emission to ⁸Be(0) is < 10% (1957BO83: see also (1959MA34) in ⁹Be(n, n')⁹Be*, and (1962ST12)). At E_α = 25.4 MeV, the continuum has been analyzed in terms of a combination of three- and four-body breakup. At low energies the results are consistent with a mixture of ⁹Be + α → ⁸Be(0) + α + n, ⁹Be*(2.4) → 2α + n or ⁵He + ⁴He (1962BR14). The third excited state is located at E_x = 3.04 ± 0.03 MeV, with Γ = 300 ± 50 keV (1964LU02). See also (1958BL57, 1959PI45, 1962ST12, 1964GO1K, 1965SA1K) and ¹³C.

29. 9Be(7Li, 8Li)8Be

Qm = 0.367

Angular distributions of ⁸Li nuclei observed for E(⁷Li) = 2 to 4.0 MeV, show pronounced peaks at θ_lab = 60° to 30°. The decrease of peak angle with increasing energy suggests a neutron transfer process (1957NO17, 1959NO40, 1960NO1A). The radial distribution of the ⁹Be neutron is deduced for R = 15 to 30 fm (1960AL1H, 1960GE1B). See also (1963LE10, 1965PO1F).

30. (a) 9Be(14N, 14N)9Be

(b) 9Be(16O, 16O)9Be

Elastic scattering in reactions (a) and (b) for E_c.m. = 3 to 15 MeV has been studied for angles near 90° (c.m.). The fact that no diffraction structure was found may reflect a more diffuse surface for ⁹Be than for ¹²C (1961KU1D, 1963KU1L). At E(¹⁴N) = 27.3 MeV no agreement is found with the predictions of a sharp cut-off model for elastic scattering (1959HA28). See also (1963WI1G).

31. 10B(γ, p)9Be

Qm = -6.587

See (1956GO1G).

32. 10B(n, d)9Be

Qm = -4.363

At E_n = 14 MeV, groups are observed corresponding to ⁹Be*(0, 2.43); no other groups are observed below E_x ≈ 5.5 MeV. The angular distributions of the deuterons indicate odd parity, 1/2 < J ≤ 9/2 for both states (1954RI15). See also (1955FR1F, 1956FR18, 1963CE1B, 1964TO1C) and ¹¹B.

33. 10B(p, 2p)9Be

Qm = -6.587

The summed proton spectrum at E_p = 460 MeV yields Q = -6.7 ± 0.5, -11.9 ± 0.5, -17.1 ± 0.6 (all l ≠ 0), and Q = -30.5 ± 0.6 MeV (l = 0) (1966TY01). See also (1958TY49, 1961PU1A, 1962GA09, 1962GA23). See also (1963RI1B, 1964TI02) and ¹⁰B.

34. 10B(d, 3He)9Be

Qm = -1.094

At E_d = 10 MeV, θ = 30°, groups corresponding to ⁹Be*(0, 1.7, 2.4, 3.0) are observed with relative intensities 1.0/0.07/0.70/0.16 (1965SY02).

35. 10B(t, α)9Be

Qm = 13.227

At E_t = 1 MeV, α-groups are observed corresponding to ⁹Be*(2.39, 3.06) (1955AL57). See also (1963HO19).

36. 10B(14N, 15O)9Be

Qm = 0.706

At E(¹⁴N) = 27.5 MeV, the ground state angular distribution shows a single maximum at θ_c.m. = 30° (σ(θ) = 1.3 mb/sr). The total ground-state transfer cross section is 1.34 ± 0.30 mb, corresponding to an interaction radius R_min ≈ 2.2(A^1/3₁ + A^1/3₂) fm (1962NE01).

37. 11B(n, t)9Be

Qm = -9.561

Not reported.

38. (a) 11B(p, 3He)9Be	Qm = -10.325
(b) 11B(p, pd)9Be	Qm = -15.819

Not reported. For reaction (b), see (1964BA1C).

39. 11B(d, α)9Be

Qm = 8.028

Alpha groups are reported corresponding to states at (1.75), 2.4 and 3.0 MeV (1956BO18, 1958KA31, 1958MI1C). The width of the 1.75 MeV structure is 224 ± 25 keV (1958KA31, 1966PU02). The energy of the 2.4 MeV state is 2422 ± 5 keV (1951VA08), 2431 ± 6 keV (1954EL10), 2424 ± 5 keV (1956BO18). The next state is at 3.02 ± 0.03 MeV (1955LE36), 3.05 ± 0.03 MeV (1956BO18). Its width is ≈ 0.3 MeV (1956BO18), Γ_c.m. = 257 ± 25 keV (1958KA31, 1966PU02). See also (1955HO48, 1961TE02, 1963RO22, 1964GR19, 1964YA1A).

The ratio of the γ-decay width to the total width, Γ_rad/Γ, of the 2.4 MeV state is (1.15 ± 0.15) × 10^-4 (1964PU04). Since Γ_rad is known from (e, e') (see (1962ED02) and Table 9.4 (in PDF or PS)), Γ = 1.0 ± 0.2 keV. For the 1.7 MeV state Γ_rad/Γ < 2.6 × 10^-5 (1964PU04, 1966PU02).

40. 12C(n, α)9Be

Qm = -5.704

Analysis of 128 cloud chamber stars involving ⁹Be*(2.4) leads to the conclusion that the probability of ⁹Be*(2.4) → n + ⁸Be(0) is 13 ± 5 % (1965MO09). See also (1955GR21, 1962BA15, 1962BA25, 1963AL10, 1963DA12, 1963SE08, 1964BR25, 1964CH28).

41. 13C(γ, α)9Be

Qm = -10.651

See (1953MI31).