A=10Be (1974AJ01)

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¹⁰Be (1974AJ01)

(See Energy Level Diagrams for ¹⁰Be)

GENERAL: See also (1966LA04) and Table 10.1 [Table of Energy Levels] (in PDF or PS).

Shell model: (1961KO1A, 1968FA1B, 1969SA1A, 1970BO35, 1970KA32, 1973KU03, 1973SA30).

Cluster and alpha-particle model: (1973KU03).

Special levels: (1970BO35, 1970FR1C, 1970PE18, 1973SA30).

Electromagnetic transitions: (1965ST22, 1973SA30).

Astrophysical questions: (1967KO1F, 1967SH1B, 1971LE33, 1971RA1K, 1972SI1G, 1973LA19, 1973RA37, 1974SI1H).

Special reactions: (1967KO1F, 1967SH1B, 1968YI01, 1969AR13, 1969GA18, 1969GO1H, 1969YI1A, 1971AR02, 1971LE33, 1971RA1K, 1972AM04, 1972PN1A, 1972SI1G, 1972VO06, 1973KO1D, 1973KU03, 1973LA19, 1973VO1G, 1973WI15).

Pion capture and reactions (See also reaction 12.): (1971DA10, 1971KA62, 1972FA14, 1972FU1C, 1973KA1D).

Other topics: (1968FA02, 1968FA1B, 1968JO1E, 1968NE1C, 1969SA1A, 1970FO1B, 1970PE18, 1971BA2Y, 1971ST40, 1972AN05, 1972CA37, 1972PN1A, 1973BU20, 1973JU2A, 1973KU03, 1973MA48, 1973MU11).

Ground-state properties: (1968FA02, 1968FA1B, 1971ST40, 1973SA30).

1. ¹⁰Be(β^-)¹⁰B Q_m = 0.5559

The half-life is (1.6 ± 0.2) × 10⁶ y (1972EM01), (1.7 ± 0.4) x 10⁶ y (1972MC26) and (1.5 ± 0.3) × 10⁶ y (1972YI01): we adopt τ_1/2 = (1.6 ± 0.2) × 10⁶ y: log ft = 13.42 (B. Zimmerman and G. Fox, private communication). The spectrum is of the D₂ type (1950WU1A). For a discussion of astrophysical and nuclear chronology considerations see (1972YI01). See also (1969VA1C, 1970WA11; theor.) and (1966BR1N).

2. (a) ⁷Li(t, γ)¹⁰Be Q_m = 17.251
(b) ⁷Li(t, n)⁹Be Q_m = 10.4389 E_b = 17.251
(c) ⁷Li(t, p)⁹Li Q_m = -2.397
(d) ⁷Li(t, d)⁸Li Q_m = -4.2249
(e) ⁷Li(t, α)⁶He Q_m = 9.837

The yield of γ₀ and γ₁ (to ¹⁰Be*(0, 3.4)) has been studied at 90° for E_t = 0.5 to 3.0 MeV. The γ₁ yield shows a peak at E_t = 1.85 MeV, Γ_lab ≈ 0.5 MeV. The γ₀ yield peaks near the same energy but with a width Γ_lab ≈ 1.5 MeV (1973BL1B).

The neutron yield exhibits a weak structure at E_t = 0.24 MeV and broad resonances at E_t ≈ 0.77 MeV [Γ = 160 ± 50 keV] and 1.74 MeV (1960SE12, 1961VA43, 1962SE1A).

The yields of ⁹Li and ⁸Li (reactions (c) and (d)) have been studied from threshold to E(⁷Li) = 21 MeV (1970CH1Q) and E_t = 6.5 MeV (1973AB10). A sharp minimum is observed in the ⁹Li yield at E(⁷Li) ≈ 13.6 MeV (1970CH1Q) and E_t = 5.62 MeV (1973AB10). It may correspond to a T = 2 state in ¹⁰Be at E_x = 21.2 MeV, Γ_c.m. = 0.4 MeV (1970CH1Q, 1973AB10).

For reaction (e) see (1966LA04). See also ⁶He, ⁸Li, ⁹Li and ⁹Be.

3. ⁷Li(α, p)¹⁰Be Q_m = -2.5638

Angular distributions of the p₀ and p₁ groups have been measured at E_α = 30 MeV (1960KL03, 1972ME07). See also (1966LA04).

4. ⁷Li(⁷Li, α)¹⁰Be Q_m = 14.784

Angular distributions are reported for E(⁷Li) = 2.1 to 5.75 MeV (1969CA1A; α₁, α_2+3+4+5), 3.5 to 5.75 MeV (1969CA1A; α₀) and 30.3 MeV (1971GL07; α-groups to ¹⁰Be*(0, 3.4, 6.0, 7.4, 9.4, 10.7, 11.9, 17.9)). (1971GL07) also report an α-group corresponding to ¹⁰Be*(18.8). See also (1970OG1A), (1966RO1E; theor.) and ¹⁴C in (1976AJ04).

5. ⁹Be(n, γ)¹⁰Be Q_m = 6.8120
Q₀ = 6811.9 ± 0.4 keV (1966GR18);
Q₀ = 6812.5 ± 1.0 keV (1967RA24).

The thermal capture cross section is 9.2 ± 1.0 mb (1973MU14). Reported γ transitions are displayed in Table 10.2 (in PDF or PS) (1960BA01, 1961JA19, 1963DR02, 1966GR18, 1969WE10). See (1968FOZY) for astrophysical considerations. See also (1968RO1H).

6. ⁹Be(n, n)⁹Be E_b = 6.8120

The older cross section data is summarized in (1964ST25). More recent measurements of the total cross section are reported for E_n = 0.5 to 20 MeV ((1971SC1P), and R.B. Schwartz, private communication), 1.9 to 4.6 MeV (1968JO1F), 2.5 to 15 MeV (1971FO1P, 1971FO24), 13.70 to 14.60 MeV (1968HU17, 1969AN1E, 1970AN1F), 23 to 45 MeV (1972BU1T), 36.3 to 58.9 MeV (1972AU01: at five energies in this range) and at a neutron momentum of 10 GeV/c (1968EN1A). Angular distributions are summarized in (1970GA1A). See also ⁹Be. The coherent scattering length (thermal, bound) is 7.74 ± 0.10 fm (1973MU14).

Five resonances are reported in the total cross section, at E_n = 0.63, 0.82, 2.73, (2.85) and 4.3 MeV; see Table 10.3 (in PDF or PS). Polarization and differential cross sections are reported for E_n = 0.2 to 2 MeV by (1961LA1A, 1962EL01, 1964LA04). Analysis of these data leads to the 3^-, 2⁺ assignments for ¹⁰Be*(7.37, 7.55) (1964LA04). Below E_n = 0.5 MeV the scattering cross section reflects the effect of bound 1^- and 2^- states, presumably ¹⁰Be*(5.960, 6.26). There is also indication of interference with s-wave background and with a broad l = 1, J^π = 3⁺ state (1964LA04). The structure at E_n = 2.73 MeV is ascribed to two levels: a broad state at about 2.85 MeV with J^π = 2⁺, and a narrow one, Γ ≈ 100 keV, at E_n = 2.73 MeV with a probable assignment of J^π = 4^- (1951BO45, 1966SC16). The 4^- assignment results from a study of the polarization of the n₀ group at E_n = 2.60 to 2.77 MeV. A rapid variation of the polarization over this interval is observed, and the data are consistent with 4^- (l = 2) for ¹⁰Be*(9.27) (1966SC16). The polarization of the n₀ group has also been studied at E_n = 4 MeV (1967GO36). See also (1966DA1B). A weak dip at E_n ≈ 4.3 MeV is ascribed to a level with J ≥ 1 (1961FO07).

See also (1966LA04), (1969MA39), (1966CH1C) and (1966AG1A, 1966JA08, 1966SE1E, 1967BE1F, 1967HO1F, 1972FR09; theor.).

7. (a) ⁹Be(n, n')⁹Be* E_b = 6.8120
(b) ⁹Be(n, 2n)⁸Be Q_m = -1.6651

Data on non-elastic cross sections are summarized by (1964ST25). The processes involved include (n, 2n) and (n, n')⁹Be* → n + ⁸Be; the (n, α) process is relatively weak. The total non-elastic cross section rises rapidly from threshold to 730 ± 100 mb at E_n = 5.2 MeV (1968EA1B). The cross section is ≈ 600 mb at E_n = 6 MeV and then falls slowly to 500 mb at 14 MeV. In the range 3.5 to 6.0 MeV, ⁹Be(n, n')⁹Be*(2.4) accounts for about half of the non-elastic cross section (1959MA34: see (1964ST25)). The (n, 2n) cross section increases slowly from E_n = 2.00 to 2.70 (the threshold for the process ⁹Be(n, n')⁹Be*(2.4) → n + ⁸Be) and then sharply, reaching a plateau with a value ≈ 580 mb at 6.40 MeV (1969HO45, 1973BL03). See also (1968EA1B).

See also (1966LA04), (1966JE1B) and (1966FE04, 1966SA20, 1967RO1E, 1968GR1F, 1969MA39, 1969PR17, 1971AL1E).

8. ⁹Be(n, p)⁹Li Q_m = -12.836 E_b = 6.8120

See (1966LA04, 1972ED01) and (1970BA1L).

9. ⁹Be(n, d)⁸Li Q_m = -14.664 E_b = 6.8120

The cross section for the (n, d) reaction has been measured for E_n = 16.3 to 18.7 MeV (1969SC05).

10. ⁹Be(n, t)⁷Li Q_m = -10.4389 E_b = 6.8120

See (1966JE1B, 1966LA04) and (1972BI1E).

11. ⁹Be(n, α)⁶He Q_m = -0.602 E_b = 6.8120

The cross section for production of ⁶He shows a smooth rise to a broad maximum of 104 ± 7 mb at 3.0 MeV, followed by a gradual decrease to 70 mb at 4.4 MeV. No indication of resonance is found at E_n = 2.7 MeV (1957ST95). From E_n = 3.9 to 8.6 MeV, the cross section decreases smoothly from 100 mb to 32 mb (1961BA53). At E_n = 14.4 MeV, the total cross section for the α₀ transition is 11.7 ± 1.8 mb (1967PA03). See also (1966JE1B, 1966LA04) and (1970BA1L).

12. ⁹Be(p, π⁺)¹⁰Be Q_m = -133.539

At E_p = 185 MeV the π⁺ spectrum shows groups corresponding to ¹⁰Be*(0, 3.37 ± 0.12, 6.07 ± 0.13, 7.39 ± 0.13, 9.31 ± 0.24, 11.75 ± 0.11). Angular distributions have been obtained for the π⁺ corresponding to these six states (1973DA09). See also reaction 3 in ¹⁰C and (1971DA10).

13. ⁹Be(d, p)¹⁰Be Q_m = 4.5873
Q₀ = 4.590 ± 0.008 (1967SP09).

Angular distributions of proton groups have been studied at many energies. Except at the lowest energies the stripping process appears to dominate: see (1966LA04) for the earlier references and (1968BE1E: 0.30 to 1.0 MeV; p₀), (1973SA1Q: 0.9 to 3.1 MeV; p₀, p₁), (1969RO12: 2.8 MeV; p₀, p₁ and p to ¹⁰Be*(5.958, 5.960)), (1970PO03: 4.50 to 6.0 MeV; p₀, p₁), (1964SC12, 1967SC29: 11.8 MeV; p₀, p₁) and (1969AR1B: 15 MeV; p₀). The angular distributions show l_n = 1 transfer for ¹⁰Be*(0, 3.37, 5.958), l_n = 0 transfer for ¹⁰Be*(5.960, 6.26) and l_n = 2 transfer for ¹⁰Be*(7.37). ¹⁰Be*(6.18, 7.54) are also populated. See (1954JU23, 1969RO12) and Table 10.4 (in PDF or PS) in (1966LA04).

Attempts to understand the γ-decay of ¹⁰Be*(5.96) and its population in ⁹Be(n, γ)¹⁰Be led to the discovery that it consisted of two states separated by 1.6 ± 0.5 keV. The lower of the two has J^π = 2⁺ and decays primarily by a cascade transition via ¹⁰Be*(3.37) [it is the state fed in the ⁹Be(n, γ) decay]; the higher state has J^π = 1^- and goes mainly by a crossover to ¹⁰Be_g.s.. Angular correlations measured with the γ-ray detector located normal to the reaction plane (≡ angular distributions) lead to l_n values consistent with the assignments of 2⁺ and 1^- for ¹⁰Be*(5.9658, 5.9660) obtained from the character of the γ-decay (1969RO12). ¹⁰Be*(6.18) decays primarily to ¹⁰Be*(5.9660): E_γ = 219.4 ± 0.3 keV (1969AL17). See Table 10.4 (in PDF or PS) for a listing of the information on radiative transitions obtained in this reaction (1969AL17, 1969RO12), and lifetime measurements (1966WA10, 1968FI09, 1969AL17). For (p, γ) correlations through ¹⁰Be*(3.37) see (1966LA04) and (1967FA03, 1969CA1F).

The probabilities p_3/2 for transfer of a neutron with angular momentum 3/2 have been determined for the p₀ and p₁ groups using vector polarized deuterons with E_d = 10 and 12 MeV, and compared with the shell model calculations of (1965CO25, 1967CO32) [(1970FI07); and see also (1967SC29)]. For polarization measurements see ¹¹B in (1975AJ02) and (1966LA04).

See also (1968LA1F), (1966WA1C, 1967LE1F, 1967WA1C, 1967YO1C, 1968SC1E, 1969CO1H) and (1971JO22, 1972DZ06, 1973DO02; theor.).

14. ⁹Be(t, d)¹⁰Be Q_m = 0.5544

The d₀ group has been observed at E_t = 1.6 to 3.5 MeV (1967BI1E). See also (1969NA04) and ¹²B in (1975AJ02).

15. ⁹Be(α, ³He)¹⁰Be Q_m = -13.7665

Not reported.

16. ⁹Be(¹⁴N, ¹³N)¹⁰Be Q_m = -3.742

See (1973TO05; theor.).

17. ⁹Be(¹⁸O, ¹⁷O)¹⁰Be Q_m = -0.679

The angular distribution has been measured at E(¹⁸O) = 16 and 20 MeV (1971KN05).

18. (a) ¹⁰Be(p, p)¹⁰Be
(b) ¹⁰Be(d, d)¹⁰Be

Angular distributions of the p₀ and p₁ groups have been measured at E_p = 12.0 to 16.0 MeV. The elastically scattered deuterons have been studied at E_d = 12.0 and 15.0 MeV. B(E2) for the ¹⁰Be*(3.4) γ / → ¹⁰Be(0) transition is 23.8 e² · fm⁴ (from a comparison of the angular distributions with DWBA predictions) (1970AU02).

19. ¹⁰B(n, p)¹⁰Be Q_m = 0.2266

See (1966GO1D, 1970NE03).

20. ¹⁰B(t, ³He)¹⁰Be Q_m = -0.5372

Not reported.

21. ¹¹B(γ, p)¹⁰Be Q_m = -11.2294

Transitions to ¹⁰Be*(3.4) from the upper region of the giant resonance in ¹¹B are reported to be about twice as intense as those from the lower region (1971PA10): see ¹¹B in (1975AJ02). Angular distributions of the p₀ and p₁ groups have been measured with E_bs = 18.5 MeV (1970SO03). See also (1969MU10).

22. ¹¹B(n, d)¹⁰Be Q_m = -9.0047

The angular distribution of the d₀ group has been measured at E_n = 14.4 MeV (1968MI10, 1971MI12).

23. ¹¹B(e, ep)¹⁰Be Q_m = -11.2294

See (1969BA1F; theor.).

24. ¹¹B(p, 2p)¹⁰Be Q_m = -11.2294

Structure is observed in the summed proton spectrum corresponding to Q = -10.9 ± 0.35, -14.7 ± 0.4, -21.1 ± 0.4, -35 ± 1 MeV: see (1966LA04, 1966TY01). See also (1971RA26), (1966JA09, 1967KO1B, 1968JA1D; theor.) and ¹¹B in (1975AJ02).

25. ¹¹B(d, ³He)¹⁰Be Q_m = -5.7356

Angular distributions have been obtained for the ³He group to ¹⁰Be(0) at E_d = 11.8 MeV (1967FI07) and at 22 MeV (1971ST05: also ³He to ¹⁰Be*(3.4)).

26. ¹¹B(t, α)¹⁰Be Q_m = 8.585

Angular distributions of α₀ and α₁ have been measured for E_t = 1.0 to 2.1 MeV (1969SI12).

27. ¹¹B(¹⁴N, ¹⁵O)¹⁰Be Q_m = -3.937

Angular distributions of the ground-state transitions have been measured at E(¹⁴N) = 41, 77 and 113 MeV (1971LI11). See also (1973SC1J) and (1973DE35; theor.).

28. ¹²C(⁶Li, ⁸B)¹⁰Be Q_m = -21.443

At E(⁶Li) = 80 MeV, ¹⁰Be*(0, 3.37, 5.95 ± 0.05) are strongly populated. There is also some evidence for the excitation of ¹⁰Be*(9.27 ± 0.1). Angular distributions have been measured to the first three of these states (1973CE1B).

29. ¹²C(¹¹B, ¹³N)¹⁰Be Q_m = -9.286

See (1969BR1D).

30. ¹³C(n, α)¹⁰Be Q_m = -3.836

See ¹⁴C in (1976AJ04).

31. (a) ¹³C(¹¹B, ¹⁴N)¹⁰Be Q_m = -3.679
(b) ¹⁵N(¹¹B, ¹⁶O)¹⁰Be Q_m = 0.898
(c) ¹⁶O(¹¹B, ¹⁷F)¹⁰Be Q_m = -10.629

See (1969BR1D).