A=10Be (2004TI06)

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¹⁰Be (2004TI06)

(See Energy Level Diagrams for ¹⁰Be)

GENERAL: References to articles on general properties of ¹⁰Be published since the previous review (1988AJ01) are grouped into categories and listed, along with brief descriptions of each item, in the General Tables for ¹⁰Be located on our website at: (nucldata.tunl.duke.edu/nucldata/General_Tables/10be.shtml).

See also 2 in (1988AJ01) [Electromagnetic Transitions in A = 5-10] (in PDF or PS), 10.5 [Table of Energy Levels] (in PDF or PS) and 10.6 [Electromagnetic transitions in ¹⁰Be] (in PDF or PS).

The interaction nuclear radius of ¹⁰Be is 2.46 ± 0.03 fm [(1985TA18), E = 790 MeV/A; see also for derived nuclear matter, charge and neutron matter r.m.s. radii].

B(E2)(↑) for ¹⁰Be*(3.37) = 52 ± 6 e² · fm⁴ (1987RA01);

B(E2)(↓) for ¹⁰Be*(3.37) = 10.5 ± 1.0 e² · fm⁴.

¹⁰Be atomic excitations: Isotope shifts for various ¹S and ¹D Rydberg series atomic excitations in ⁹Be and ¹⁰Be were measured in (1988WE09).

1. ¹⁰Be(β^-)¹⁰B Q_m = 0.5560

The half-life of ¹⁰Be is (1.51 ± 0.04) × 10⁶ years; this is the weighted average of 1.51 ± 0.06 Ma (1987HO1P), 1.53 ± 5% Ma (1993MI26) and 1.48 ± 5% Ma (1993MI26). The log ft = 13.396 ± 0.012. For the earlier work see (1974AJ01). See also (1992WA02, 1990HO28, 1998MA36).

2. ⁴He(⁶He, ⁶He)⁴He E_b = 7.4133

At E(⁶He) = 151 MeV, angular distributions were measured to investigate two-neutron exchange and the cluster configurations that dominate in the reaction. The data are consistent with a significant spatial correlation for the exchanged neutrons (1998TE03). Measurements at lower energies, E_cm = 11.6 MeV and 15.9 MeV, indicate that a simple di-neutron exchange is not dominant and give evidence that the structure of ⁶He is more complex than an alpha-plus-di-neutron model (1999RA15). See also (2000BB06).

3. (a) ⁶Li(⁶He, ¹⁰Be + d)
(b) ⁶Li(⁶He, ⁶He + α)²H Q_m = -1.4738

Molecular cluster states in ¹⁰Be were studied by bombarding ⁶Li targets with E(⁶He) = 17 MeV projectiles and detecting the ¹⁰Be + d and ⁶He + ⁴He reaction products (1999MI39). In reaction (a) reconstruction of the missing energy indicates that ¹⁰Be*(0, 3.37) participate in the reaction as well as unresolved states at 6 MeV and 7.5 MeV. In reaction (b) the 10.2 MeV level is observed, and due to its apparent cluster nature it is suggested that this state could be the 4⁺ member in the rotational band (6.18 [0⁺], 7.54 [2⁺], 10.2 [4⁺]) [J^π in brackets]. However, see reaction 7 which indicates J^π = 3^- for E_x = 10.2 MeV.

4. (a) ⁷Li(t, γ)¹⁰Be Q_m = 17.2509
(b) ⁷Li(t, n)⁹Be Q_m = 10.4387 E_b = 17.2509
(c) ⁷Li(t, p)⁹Li Q_m = -2.3857
(d) ⁷Li(t, t)⁷Li
(e) ⁷Li(t, α)⁶He Q_m = 9.8376

The yield of γ₀ and γ₁ has been studied for E_t = 0.4 to 1.1 MeV [¹⁰Be*(17.79) is said to be involved]: see (1984AJ01). The neutron yield exhibits a weak structure at E_t = 0.24 MeV and broad resonances at E_t ≈ 0.77 MeV [Γ_lab = 160 ± 50 keV] and 1.74 MeV: see (1966LA04) [¹⁰Be*(17.79, 18.47)]. The total cross section for reaction (c), the yield of neutrons (reaction (b) to ⁹Be*(14.39)), and the yield of γ-rays from ⁷Li*(0.48) (reaction (d)) all show a sharp anomaly at E_t = 5.685 MeV: J^π = 2^-; T = 2 is suggested for a state at E_x = 21.22 MeV. The total cross section for α₀ (reaction (e)) and the all-neutrons yield do not show this structure: see (1984AJ01, 1988AJ01). An additional anomaly in the proton yield is reported at E_t = 8.5 MeV [¹⁰Be*(23.2)] [see (1987AB15)]. For reaction (c) a reanalysis of the proton yields indicate two states at E_x = 21.216 ± 0.023 and 23.138 ± 0.140 MeV with Γ_cm = 80 ± 30 and 440 ± 178 keV, respectively (1990GU36). For reaction (e) the angular distributions of α₀ and α₁ products were measured at E_t = 151 and 272 keV, and the analysis suggests possible evidence for a 2⁺ resonance, ¹⁰Be*(17.3), at E_res = 117 ± 3 keV with Γ_lab = 253 ± 1 keV (1987AB09). Differential cross sections and S-factors are reported by (1983CE1A) for E_t = 70 to 110 keV for ⁶He*(0, 1.80). The zero-energy S-factor for ⁶He*(1.80) is 14 ± 2.5 MeV · b. The relevance to a Li-seeded tritium plasma is discussed by (1983CE1A). See also (1985CA41; astrophys.).

5. ⁷Li(³He, π⁺)¹⁰Be Q_m = -122.3379

Cross sections have been measured to ¹⁰Be*(3.37, 6.2 [u], 7.4 [u] [u = unresolved]) at E(³He) = 235 MeV. The ground-state group is not seen: its intensity at θ_lab = 20° is ≤ 0.1 of that to ¹⁰Be*(3.37) (1984BI08).

6. ⁷Li(α, p)¹⁰Be Q_m = -2.5629

Angular distributions were measured at E_α = 65 MeV (1994HA16). Observed states are shown in 10.8 (in PDF or PS). For ¹⁰Be*(11.76) the angular distribution is consistent with L = 3 which supports a J^π = 4⁺ assignment. It is suggested that the 11.76 MeV state is the 4⁺ member of the ground-state K^π = 0⁺ rotational band (g.s. [0⁺], 3.37 [2⁺], 11.76 [4⁺] [J^π in brackets]).

7. (a) ⁷Li(⁷Li, p + ⁹Li)⁴He Q_m = -4.8526
(b) ⁷Li(⁷Li, d + ⁸Li)⁴He Q_m = -6.69185
(c) ⁷Li(⁷Li, t + ⁷Li)⁴He Q_m = -2.46691
(d) ⁷Li(⁷Li, α)¹⁰Be Q_m = 14.7840
(e) ⁷Li(⁷Li, α + ⁶He)⁴He Q_m = 7.3707
(f) ⁷Li(⁷Li, α + ⁹Be)n Q_m = 7.9718

Resonant particle decay spectroscopy measurements have been reported for reactions (a), (b), (c), (e), (f): see 10.9 (in PDF or PS) for an overview of experimental conditions. These measurements are particularly well-suited for spectroscopic studies of levels that decay to excited states of the component isotopes, i.e. α₁ + ⁶He*(1.8). Values of Γ_α/Γ = (3.5 ± 1.2) × 10^-3 and 0.16 ± 0.04 for ¹⁰Be*(7.542, 9.6), respectively, are determined by (2002LI15). See also (2004AR01) for a cluster model analysis.

New evidence suggests that the previously accepted level energy at 9.4 MeV corresponds to the level presently observed at 9.6 MeV (1996SO17, 2001MI39, 2002LI15). (1997CU03, 2001CU06) measured E_x = 9.56 ± 0.02 MeV and determined Γ_cm = 141 ± 10 keV and J^π = 2⁺. Assuming that the ¹⁰Be*(9.56) state is 2⁺ suggests that it is probably a member of the K^π = 1⁺ band and the 3^- 10.15 MeV level is probably in the K^π = (1^-, 2^-) band (2001CU06, 2002LI15). See also (2004MI07) and Fig. 8 in (2002LI15).

The work of (1996SO17) reported a new level that decays by α-emission at E_x = 10.2 MeV with Γ < 400 keV. The level energy is identified as E_x = 10.15 ± 0.02 MeV by (2001CU06) who also determined Γ_cm = 296 ± 15 keV and, based on α + ⁶He decay angular correlations, J^π = 3^-. This is in contrast with a J = 4 spin value that was suggested by (1996SO17). The 10.2 MeV level appears to have a small Γ_n; it is neither observed in fast neutron capture nor in the ⁹Be + n decay channel.

A natural parity state at 11.23 ± 0.05 MeV with Γ_cm = 200 ± 80 keV is identified by (2001CU06) along with inconclusive evidence for states at 13.1, 13.9 and 14.7 MeV. (2002LI15) observed a new state at 18.15 ± 0.05 MeV with Γ = 100 ± 30 keV; based on reaction systematics they deduce J^π = 0^-. See 10.10 (in PDF or PS) for other states observed in (2003FL02).

For reaction (d), angular distributions of α₁ and α_2+3+4+5 were reported in (1969CA1A). Groups corresponding to ¹⁰Be*(0, 3.4, 6.0, 7.4, 9.4, 10.7, 11.9, 17.9) and possibly ¹⁰Be*(18.8) were reported in (1971GL07). See (1974AJ01).

8. ⁹Li(p, α)⁶He Q_m = 12.2233 E_b = 19.6366

A calculation estimating the impact of ⁹Li(p, α)⁶He β / → ⁶Li and other reactions on the production of primordial ⁶Li in Big Bang nucleosynthesis is given in (1997NO04).

9. ⁹Be(n, γ)¹⁰Be Q_m = 6.8122

The thermal capture cross section is 8.49 ± 0.34 mb (1986CO14). Reported γ-ray transitions are displayed in 10.7 (in PDF or PS) (1983KE11). Partial cross sections involving ¹⁰Be*(0, 3.37, 5.96) are listed in (1987LY01). See also the references cited in (1988AJ01).

Retardation of E1 strength was found in a measurement of the capture γ-rays from ⁹Be + n using E_n = 622 keV neutrons to populate the J^π = 3^- D-wave resonance at ¹⁰Be*(7.372) (1994KI09); Γ_n = 17.5 keV. Capture to the J^π = 2⁺ states at ¹⁰Be*(3.368, 5.958) was observed, and Γ_γ = 0.62 ± 0.06 and 0.11 ± 0.08 eV were deduced, respectively. Simple capture models indicate that capture to the 3368 keV state is appreciably hindered, which is explained by assuming a strong coupling between the d-state single particle neutron motion and the E1 giant resonance.

10. (a) ⁹Be(n, n)⁹Be E_b = 6.8122
(b) ⁹Be(n, 2n)⁸Be Q_m = -1.6654

The scattering amplitude (bound) a = 7.778 ± 0.003 fm, σ_free = 6.151 ± 0.005 b (1981MUZQ). The difference in the spin-dependent scattering lengths, b⁺ - b^- is +0.24 ± 0.07 (1987GL06). See also (1987LY01). Total cross section measurements have been reported for E_n = 0.002 eV to 2.6 GeV/c [see (1979AJ01, 1984AJ01)] and at 24 keV (1983AI01), 7 to 15 MeV (1983DA22; also reaction cross sections) and 10.96, 13.89 and 16.89 MeV (1985TE01; for n₀ and n₂).

Observed resonances are displayed in 10.11 (in PDF or PS). Analysis of polarization and differential cross section data leads to the J^π = 3^-, 2⁺ assignments for ¹⁰Be*(7.37, 7.55), respectively. 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. 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 at E_n = 2.73 MeV, Γ_cm ≈ 100 keV, with a probable assignment of J^π = 4^-. 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). A weak dip at E_n ≈ 4.3 MeV is ascribed to a level with J ≥ 1. See (1974AJ01) for references. The analyzing power has been measured for E_n = 1.6 to 15 MeV [see (1984AJ01)] and at E_{pol. n} = 9 to 17 MeV (1984BY03; n₀, n₂).

The non-elastic and the (n, 2n) cross sections rise rapidly to ≈ 0.6 b (≈ 0.5 b for (n, 2n)) at E_n ≈ 3.5 MeV and then stay approximately constant to E_n = 15 MeV: see (1979AJ01, 1984AJ01). For total γ-ray production cross sections for E_n = 2 to 25 MeV, see (1986GO1L). See also references cited in (1988AJ01).

11. (a) ⁹Be(n, p)⁹Li Q_m = -12.8244 E_b = 6.8122
(b) ⁹Be(n, d)⁸Li Q_m = -14.6636
(c) ⁹Be(n, t)⁷Li Q_m = -10.4387

Cross sections have been measured at E_n = 14.1 - 14.9 MeV for reaction (a), and at 16.3 - 18.8 MeV for reaction (b): see (1979AJ01). For reaction (c), measurements have been reported at E_n = 13.3 - 15.0 (t₁), at 22.5 MeV (see (1979AJ01)), and at 14.6 MeV (1987ZA01). A measurement of the ⁹Be(n, tγ₁)⁷Li inclusive cross sections that encompassed E_n = 12 - 200 MeV observed peaks corresponding to ¹⁰Be*((17.79), 18.55, 21.22, 22.26, (24.0)) (2002NE02). For the 18.55 and 24.0 MeV states, the peaks were observed at 18.76 and 23.4 MeV, respectively.

12. ⁹Be(n, α)⁶He Q_m = -0.6011 E_b = 6.8122

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. From E_n = 3.9 to 8.6 MeV, the cross section decreases smoothly from 100 mb to 32 mb. Excitation functions have been measured for α₀ and α₁ for E_n = 12.2 to 18.0 MeV: see (1979AJ01) for references.

13. (a) ⁹Be(p, π⁺)¹⁰Be Q_m = -133.5403
(b) ⁹Be(p, K⁺)

Angular distributions for reaction (a) have been studied at E_p = 185 to 800 MeV [see (1984AJ01)] and at E_{pol. p} = 650 MeV (1986HO23; to ¹⁰Be*(0, 3.37)). States at E_x = 6.07 ± 0.13, 7.39 ± 0.13, 9.31 ± 0.24, 11.76 MeV have also been populated. A_y measurements involving ¹⁰Be*(0, 3.37) are reported at E_{pol. p} = 200 to 250 MeV [see (1984AJ01)] and at 650 MeV (1986HO23).

For reaction (b), the K⁺ production cross sections were measured for E_p = 835 - 990 MeV (1988KO36). Calculations for one- and two-step K⁺ production for E_p = 0.8 - 3 GeV are given in (2000PA15).

14. ⁹Be(d, p)¹⁰Be Q_m = 4.5877

Angular distributions of proton groups have been studied at many energies in the range E_d = 0.06 to 17.3 MeV and at 698 MeV [see (1979AJ01, 1984AJ01, 1988AJ01) and (1997YA02)], as well as at E_{pol. d} = 2.0 to 2.8 MeV (1984AN16, 1984DE46; p₀, p₁; also VAP) and E_d = 12.5 MeV (1987VA13; p₀, p₁). The angular distributions show l_n = 1 transfer for ¹⁰Be*(0, 3.37, 5.958, 7.54), l_n = 0 transfer for ¹⁰Be*(5.960, 6.26), l_n = 2 transfer for ¹⁰Be*(7.37). ¹⁰Be*(6.18, 9.27, 9.6) are also populated, as are two states at E_x = 10.57 ± 0.03 and 11.76 ± 0.02 MeV. The state reported by (1974AN27) at 9.4 MeV is most likely the 9.6 MeV 2⁺ state based on its separation from the 9.27 MeV state (2001CU06). ¹⁰Be*(9.27, 9.6, 11.76) have Γ_cm = 150 ± 20, 291 ± 20 and 121 ± 10 keV, respectively. See (1979AJ01) for references. See also (1989SZ02, 1995LY03, 1998LE27, 2000GE16).

Angular distributions and excitation functions for ⁹Be(d, p₀) and (d, p₁) were measured for the energy range E_cm = 57 - 139 keV (1997YA02, 1997YA08). Astrophysical S(E)-factors were deduced and the spectroscopic factor S = 0.92 was deduced for ⁹Be(d, p₀). (2000GE16) analyzed σ(E) and S(E) for E = 0.085 - 11 MeV and evaluated the impact of this reaction for forming heavier B, C and N nuclei in nucleosynthesis.

At E_d = 1.0 MeV, p + γ coincidences were measured. In this experiment E_x = 3368.34 ± 0.43 keV was measured, which confirms E_x = 3368.03 ± 0.03 keV [ 10.5 (in PDF or PS)] for ¹⁰Be*(3.3) (1999BU26): see reaction 55.

At E_d = 15.3 MeV the p₀ and p₁ + γ₁ double-differential cross sections were measured and evaluated with coupled-channel calculations which suggest that multistep processes are important in the reaction mechanism (2001ZE09).

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 directly in the ⁹Be(n, γ) decay]; the higher state has J^π = 1^- and decays mainly to the ¹⁰Be_g.s.. Angular distributions measured with the γ-ray detector located normal to the reaction plane lead to l_n values consistent with the assignments of 2⁺ and 1^- for ¹⁰Be*(5.9584, 5.9599) obtained from the character of the γ-decay. ¹⁰Be*(6.18) decays primarily to ¹⁰Be*(3.37): E_γ = 219.4 ± 0.3 keV for the 6.18 → 5.96 transition. See 10.12 (in PDF or PS) for a listing of the information on radiative transitions obtained in this reaction and lifetime measurements. For (p, γ) correlations through ¹⁰Be*(3.37) see (1987VA13) and references in (1974AJ01). For polarization measurements see ¹¹B in (1990AJ01).

15. ⁹Be(α, ³He)¹⁰Be Q_m = -13.7654

Angular distributions have been studied at E_α = 65 MeV to ¹⁰Be*(0, 3.37, 5.96, 6.26, 7.37, 7.54, 9.33 [u], 11.88). DWBA analyses of these lead to spectroscopic factors (1980HA33) which are in poor agreement with those reported in other reactions: see (1984AJ01).

Cluster model analyses of the reaction (1996VO03, 1997VO06, 1997VO17) explain the levels between 5.95 and 6.26 MeV as 2α - 2n-cluster states, by analogy with cluster states in ⁹Be. The analysis further suggests that states at 5.960, 6.263, 7.371, 9.27 and 11.76 MeV (with J^π = 1^-, 2^-, 3^-, 4^- and 5^-, respectively) comprise the K^π = 1^- rotational band.

16. ⁹Be(⁶He, ⁵He)¹⁰Be Q_m = 4.946

At E(⁶He) = 25 MeV/A, 1- and 2-neutron transfer cross sections were measured in a study of n - n correlations for neutrons in ⁶He (2003GE05). The reaction was dominated by 1-neutron transfer.

17. (a) ⁹Be(⁷Li, ⁶Li)¹⁰Be Q_m = -0.4381
(b) ⁹Be(⁷Li, α + ⁶He)⁶Li Q_m = -7.8514
(c) ⁹Be(⁸Li, ⁷Li)¹⁰Be Q_m = 4.7799

Angular distributions have been measured at E(⁷Li) = 34 MeV (reactions (a) and (b)) to ¹⁰Be_g.s., S = 2.07, and ¹⁰Be*(3.4), S = 0.42 (p_1/2), 0.38 (p_3/2): see (1979AJ01). At E(⁷Li) = 52 MeV, states are reported at ¹⁰Be*(0, 3.37, ≈ 6 (multiplet), 7.5 (doublet), 9.6, 10.2 11.8) (2001MI39). At E(⁸Li) = 11 MeV (1989KO17) and 14.3 MeV (1989BE28, 1993BE22) angular distributions for ¹⁰Be*(0, 3.37) have been measured. A DWBA analysis of the E(⁸Li) = 14.3 MeV data yields spectroscopic factors of S_g.s. = 4.0 and S_3.37 = 0.2 (p_1/2). At E(⁹Be) = 20 MeV an angular distribution involving ⁸Be_g.s. + ¹⁰Be_g.s. has been measured: transitions to excited states of ¹⁰Be are very weak (1985JA09).

18. ⁹Be(⁹Be, ⁸Be)¹⁰Be Q_m = 5.1468

At E(⁹Be) = 20 MeV an angular distribution involving ⁸Be_g.s. and ¹⁰Be_g.s. was measured: transitions to excited states are weak (1985JA09). At E(⁹Be) = 48 MeV, excited states of ¹⁰Be were populated (2003AS04): see 10.13 (in PDF or PS). The excitation energy of ¹⁰Be states was deduced from the measured energy of the ⁸Be recoil, which was detected as two α particles. The α-particle energy spectra were analyzed in a CCBA model analysis to justify their interpretation of spin values.

19. ⁹Be(¹¹Be, ¹⁰Be)¹⁰Be Q_m = 6.308

The ¹⁰Be core excitations in the ¹¹Be ground state were determined by measuring ¹⁰Be fragments in coincidence with γ-rays in ⁹Be(¹¹Be, ¹⁰Be + γ)X at 60 MeV/A. The γ-rays corresponding to ¹⁰Be*(3.37, 5.96, 6.26) were observed in 6.1%, 6.6% and 9.1% of the events, respectively. This indicates a small 0d admixture to the ¹¹Be ground state which is dominated by a 1s single-particle component (2000AU02). In a different experiment at E(¹¹Be) = 46 MeV/A, γ-ray plus ¹⁰Be coincidences were observed. The γ-rays corresponding to transitions between 6.263 → 3.368 MeV, 5.96 → 0 MeV and 3.368 → 0 MeV were observed (2001CH46), though in this case excitation energies were not resolved in the charged particle spectra. See (1992WA22, 2000PA53) for calculations of spectroscopic factors. Also see (1995KE02, 1996ES01, 1999TO07).

20. ⁹Be(¹¹B, ¹⁰B)¹⁰Be Q_m = -4.642

Differential cross sections for ⁹Be(¹¹B, ¹⁰B)¹⁰Be were measured at E(¹¹B) = 45 MeV for the angular range θ_lab = 10 - 165° (2003KY01). The quasi-symmetric distributions involving ¹⁰Be*(0, 3.368) and ¹⁰B*(0.0.78, 1.74, 2.154, 3.587) were analyzed in a coupled-reaction-channels method. Spectroscopic amplitudes are discussed for all possible 1- and 2-step processes. Analysis indicates that the reaction proceeds primarily by one-step proton- or neutron transfer.

21. ⁹Be(¹⁴N, ¹³N)¹⁰Be Q_m = -3.7412

At E(¹⁴N) = 217.9 MeV, ¹⁰Be*(0, 3.37, 5.960, 6.25, 7.37, 9.27, 11.8, 15.34) states are reported with J^π = 0⁺, 2⁺, 1^-(+2⁺), 2^-, 3^-, 4^-, (5^-), (6^-), respectively (2003BO24, 2003BO38). The data are interpreted by assuming that the levels are α-cluster molecular states with the binding energy provided by the excess neutrons. In this analysis, the members of the K^π = 1^- rotational band are described by the formula, E_x ≈ 0.25 [J(J + 1) - 1 × 2] + 5.96 MeV. See also (2003HO30).

22. (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 reaction was measured in inverse kinematics by scattering 59.2 MeV ¹⁰Be projectiles from protons (2000IW02) and measuring the ¹⁰Be recoils and associated de-excitation γ-rays. Scattering reactions involving ¹⁰Be*(0, 3.77, 5.96) were observed. For the first excited state, a deformation length of δ = 1.80 ± 0.25 fm, β² = 0.635 ± 0.042 and (M_n/M_p)/(N/Z) = 0.51 ± 0.12 are deduced. For the 5.96 MeV level, the branching ratio for decay via the 3.368 MeV state is 14 ± 6% of the branch for decay directly to the ground state. For reaction (b), elastically scattered deuterons have been studied at E_d = 12.0 and 15.0 MeV: see (1974AJ01).

23. ¹⁰Be(¹¹Be, ¹¹Be)¹⁰Be

Theoretical analysis of elastic and inelastic ¹¹Be scattering suggest enhancement of the fusion process due to strong multi-step processes in the inelastic and transfer transitions of the active neutron. In some cases, a neck formation is suggested that is analogous to a "covalent bond" for ¹⁰Be - n - ¹⁰Be (1995IM01).

24. (a) ¹⁰B(γ, π⁺)¹⁰Be Q_m = -140.1262
(b) ¹⁰B(e, e'π⁺)¹⁰Be Q_m = -140.1262

Differential cross sections have been measured to ¹⁰Be*(0, 3.37) at E_γ = 230 to 340 MeV [see (1984AJ01)] and at E_e = 185 MeV (1986YA07) and 200 MeV (1984BLZY). A theoretical study of γ + N → π + N dynamics, for E_γ = 183 and 320 MeV (1994SA02), indicates that core polarization non-local effects due to off-shell dynamics must be accounted for rigorously to obtain agreement with data. See also (1990BE49) for calculations at E_γ ≈ 200 MeV and (1990ER03) for E_γ = 180 - 320 MeV.

25. ¹⁰B(μ^-, ν)¹⁰Be Q_m = 105.1024

Partial capture rates leading to the 2⁺ states ¹⁰Be*(3.37, 5.96) have been reported: see (1984AJ01). A review of muon capture rates (1998MU17), discusses a renormalization of the nuclear vector and axial vector strengths.

26. ¹⁰B(π^-, γ)¹⁰Be Q_m = 139.0142

The photon spectrum from stopped pions is dominated by peaks corresponding to ¹⁰Be*(0, 3.4, 6.0, 7.5, 9.4). Branching ratios have been obtained: those to ¹⁰Be*(0, 3.4) are (2.02 ± 0.17)% and (4.65 ± 0.30)%, respectively [absolute branching ratio per stopped pion] (1986PE05). See (1979AJ01) for the earlier work. Also see (1998NA01).

27. (a)¹⁰B(n, p)¹⁰Be Q_m = 0.2264
(b) ¹⁰B(d, 2p)¹⁰Be Q_m = -1.9982

The cross section for reaction (a) at thermal neutron energies is σ = 6.4 ± 0.5 mb, which is one order of magnitude lower than that of the (n, t) channel (1987LA16). At E_n = 96 MeV, the ¹⁰Be excitation spectra was evaluated by carrying out a multipole decomposition up to E_x = 35 MeV (2001RI02) to deduce the Gamow-Teller strength distribution; while low-lying states were unresolved, the high excitation spectra was dominated by a broad L = 1 peak that was centered at E_x = 22 MeV. Also see (1974AJ01) and ¹¹B in (1990AJ01). For reaction (b) at E_d = 55 MeV, states are reported at ¹⁰Be*(0, 3.37, 5.96, 7.37, 7.54, 9.27 [u], 9.4 [u]) [u = unresolved] (1979ST15), and angular distributions are given for the J^π = 0⁺ ¹⁰Be_g.s. and the J^π = 2⁺ states at 3.37, 5.96 and 9.4 MeV.

28. ¹⁰B(t, ³He)¹⁰Be Q_m = -0.5374

At E_t = 381 MeV, states were observed at 0, 3.37, 5.96 and 9.4 MeV with some strength at 12 - 13.25 MeV (1997DA28, 1998DA05). A proportionality between the 0-degree (t, ³He) cross section and the Gamow-Teller strength deduced from β-decay measurements is discussed. The 3.37, 5.96 and 9.4 MeV states are identified as spin-flip Gamow-Teller excitations (ΔS =1, ΔT = 1). J^π = 3⁺ is suggested for the 9.4 MeV state, though 2⁺ or 4⁺ cannot be ruled out. Shell model predictions indicate J^π = 3⁺ Isobaric Analog States (IAS) in ¹⁰Be, ¹⁰B and ¹⁰C at approximately 9, 11 and 8 MeV, respectively (1993WA06, 2001MI29). However, the uncertainty in J^π and lack of observation of these states in ¹⁰B and ¹⁰C prevents an acceptance of this suggested J^π = 3⁺ state as a new level at the present time; we associate this level with the 9.56 MeV, J^π = 2⁺ level in 10.5 (in PDF or PS). The 2⁺ states at 3.37 and 5.96 MeV are Gamow-Teller excitations and the IAS of the 3.35 and 5.3 MeV states in ¹⁰C. The values B(GT_-) = 0.68 ± 0.02 from ¹⁰B(p, n)¹⁰C*(5.38) and B(GT₊) = 0.95 ± 0.13 from ¹⁰B(t, ³He)¹⁰Be*(5.96) may indicate that the nuclear structure of ¹⁰Be and ¹⁰C differs because of the presence of the Coulomb force, giving rise to isospin symmetry violation.

29. ¹⁰B(⁷Li, ⁷Be)¹⁰Be Q_m = -1.4182

At E(⁷Li) = 39 MeV, ¹⁰Be*(0, 3.37, 5.96) states were observed (1988ET02). At this energy sequential processes are blocked, due to isospin mixing, and the one-step mechanism is most important. Also see (1989ET03).

30. ¹¹Li(β^-)¹¹Be → ¹⁰Be + n Q_m = 20.1190

New constraints on the ¹¹Li β-decay branch that feeds the ¹¹Be ground state indicate that the ¹¹Li β-delayed single neutron emission probability is P_1n = 87.6 ± 0.8% (1997BO01).

The β-delayed neutrons following ¹¹Li decay were measured by (1997MO35); results of their observations are presented in 10.14 (in PDF or PS). A different technique, utilizing a β-neutron-γ-ray triple coincidence was employed by (1997AO01, 1997AO04): see 10.15 (in PDF or PS). While the overall shape of the neutron energy spectra measured by (1997MO35) and (1997AO01, 1997AO04) are in excellent agreement, the analysis of their data leads to different interpretations and conflicting results. The measurements of (1997AO01, 1997AO04) reported involvement of a new ¹¹Be state at E_x = 8.03 MeV; this new state is implied by both an ≈ 1.5 MeV neutron in coincidence with the 2590 keV ¹⁰Be*(5.96 → 3.36) γ-ray, and an ≈ 3.6 MeV neutron in coincidence with the 3368 keV ¹⁰Be*(3.36 → 0) γ-ray. However, the interpretation of β - n coincidences by (1997MO35) included low-energy neutrons from the unobserved ¹¹Be*(3.87, 3.96) → ¹⁰Be*(3.36) + n and ¹¹Be*(6.51, 6.70, 7.03) → ¹⁰Be*(≈ 6) + n decay branches into the analysis, and with their inferred branching ratios it was not necessary to introduce a new state at 8.03 MeV.

To address the question of a possible level in ¹¹Be at E_x = 8.03 MeV, (2003FY01) developed a procedure to evaluate Doppler broadening in isotropic γ-ray decay that occurs, for example, following β-delayed neutron decay. A model was developed that indicates a well-defined γ-ray spectrum shape that depends on recoil velocity after decay, the level lifetime, and recoil energy-losses/stopping powers in the target. The 2590 keV γ-ray from ¹⁰Be*(5.958) decay was evaluated, and the observed Doppler broadening was consistent with population of this level via neutron-decay from a ¹¹Be level around E_x = 8.6 - 9.1 MeV. This interpretation favors the analysis of (1997AO01, 1997AO04).

For earlier work see (1984AJ01, 1988AJ01) where population of complex decay branches are reported.

31. ¹¹Be(p, d)¹⁰Be Q_m = 1.7206

Angular distributions were measured for E(¹¹Be) = 35 MeV/A (2000FO17, 2001WI05). The ¹⁰Be_g.s., 3.4 MeV and unresolved states near 6 MeV were observed. The spectroscopic factors for the ¹⁰Be*(3.37) state inferred from standard DWBA and coupled-channels analysis differ by roughly a factor of 1.7. A "best estimate" for describing the ¹¹Be ground-state wave function includes a 16% core excitation of the ¹⁰Be*(3.34) state [2⁺ Ä d]. Also see (1999TI04, 2000YI02). For calculations at E(¹¹Be) = 800 MeV see (1998CA18).

32. ¹¹B(γ, p)¹⁰Be Q_m = -11.228

See (1984AL22) and ¹¹B in (1990AJ01). See also (1979AJ01).

33. ¹¹B(p, 2p)¹⁰Be Q_m = -11.228

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 (1974AJ01). See also (1994SH21) for a quasi-quantum multi-step reaction model.

34. ¹¹B(d, ³He)¹⁰Be Q_m = -5.734

Angular distributions have been measured at E_d = 11.8 and 22 MeV to ¹⁰Be_g.s. [see (1974AJ01)] and at 52 MeV to ¹⁰Be*(0, 3.37, 5.96, 9.6): S = 0.65, 2.03, 0.13, 1.19 (normalized to the theoretical value for the ground state); π = + for ¹⁰Be*(9.6): see (1979AJ01).

35. ¹¹B(⁷Li, ¹⁰Be + γ)X

Fusion evaporation products from ¹¹B + ⁷Li were measured at E(⁷Li) = 5.5 - 19 MeV by detecting the reaction products and corresponding γ-rays (2000VL04). Reactions were observed indicating ¹⁰Be_g.s. and ¹⁰Be* + γ(3368). Results were used to evaluate the ⁷Li + ¹¹B fusion barrier and the angular momentum achieved in the compound nucleus.

36. ¹¹B(¹¹B, ¹²C)¹⁰Be Q_m = 4.729

See (1985PO02).

37. ¹²C(γ, 2p)¹⁰Be Q_m = -27.1846

Photo-breakup reactions on ¹²C have been reported for E_γ = 80 - 700 MeV (see 10.16 (in PDF or PS)). Two-nucleon photoemission shows promise as a means to study short-range nucleon-nucleon correlations, however it is necessary to understand the reaction mechanism and final state interactions. Between the Giant Dipole Resonance and the Δ-resonance, γ-ray absorption is primarily on clusters or pairs of nucleons which are emitted after photon absorption. Above the Δ resonance (E_x ≈ 300 MeV) γ-rays may interact with a single nucleon to form a Δ, which then either decays into a nucleon plus pion, or the Δ may interact with another nucleon leading to emission of a pair of nucleons. The missing-mass spectra show strong peaks corresponding to (1p)² and (1p1s) proton pair removal, while the (1s)² peak is weak and broad which makes that contribution difficult to identify. Ejectile energy correlations appear to indicate that final state interactions play a role at low missing mass, however at high missing mass the energy appears to be divided between the two protons and hence final state interactions are not relevant. Polarization observables were measured by (2001PO19) and asymmetries were observed to be smaller than expected. See also (1994RY02, 1996RY04, 1998RY01, 1999IR01).

38. ¹²C(e, e'2p)¹⁰Be Q_m = -27.1846

Electro-production of proton pairs on ¹²C targets has been reported for electron energies ranging from E = 0.1 - 14.5 GeV: see 10.16 (in PDF or PS). The ¹⁰Be_g.s. is observed, but low-lying resonances are not resolved. Above E_x = 25 MeV, peaks corresponding to (1p)², (1p1s) and (1s)² proton pair removal are observed. As in (γ, 2p) reactions [see reaction 37], two-nucleon emission induced by virtual photons also shows promise as a means to study short-range nucleon-nucleon correlations; however the reaction mechanism and final state interactions must be understood. See also (1996RY04, 1997RY01, 2003AN15).

39. ¹²C(π^-, n + p)¹⁰Be Q_m = 111.6032

The reaction mechanism for the absorption of stopped pions on α, np and pp clusters in ¹²C is discussed in (1987GA11).

40. ¹²C(n, ³He)¹⁰Be Q_m = -19.4666

At E_n = 40 - 56 MeV, the pulse shape response for discriminating various final-state channels resulting from n + ¹²C interactions in NE213 and BC401a liquid scintillator was measured by (1994MO41). See also (1989BR05) for calculated cross sections at E_n = 15 - 60 MeV.

41. ¹²C(⁶He, ¹⁰Be + 2α)

At E(⁶He) = 18 MeV, this reaction was studied by detecting the triple coincidence (¹⁰Be + 2α) (2004MI05). The kinematical reconstruction indicates that ¹⁰Be*(0, 3.37) and the multiplet near E_x ≈ 6 MeV participate in this reaction.

42. ¹²C(⁶Li, ⁸B)¹⁰Be Q_m = -21.4414

At E(⁶Li) = 80 MeV, ¹⁰Be*(0, 3.37, 5.96, 7.54, (9.4; J^π probably 2⁺), 11.8) are populated and the angular distribution to ¹⁰Be_g.s. has been measured: see (1976WE09, 1977WE03).

43. ¹²C(⁹Be, ¹¹C)¹⁰Be Q_m = -11.9094

The ¹⁰Be*(0, 3.368) states, and higher lying unresolved states were observed at E(⁹Be) = 40.1 MeV (1999CA48).

44. ¹²C(¹¹B, ¹³N)¹⁰Be Q_m = -9.284

At E(¹¹B) = 190 MeV, the J^π = 0⁺ ¹⁰Be_g.s. and J^π = 2⁺ excited states at ¹⁰Be*(3.36, 5.95, 9.4) excited states are observed (1998BE63).

45. ¹²C(¹²Be, α + ⁶He)¹⁴C Q_m = 2.037

Excited states in ¹⁰Be were reconstructed from the α+⁶He relative energy spectra at E(¹²Be) = 378 MeV (2001FR02). Tentative evidence was found for states at E_x = 13.2, 14.8 and 16.1 MeV, while other known levels were observed at 11.9 and 17.2 MeV.

46. ¹²C(¹²C, ¹⁴O)¹⁰Be Q_m = -20.6141

At E(¹²C) = 357 MeV, the ¹⁰Be*(0, 3.37, 5.96, 7.54, 9.4) levels were populated (1996ST29). The J^π = 0⁺ ¹⁰Be ground state is strongly populated and appears to result from a two-proton transfer which tends to leave the neutron configuration undisturbed.

47. ¹²C(¹⁵N, ¹⁷F)¹⁰Be Q_m = -14.4567

At E(¹⁵N) = 318.5 MeV, known ¹⁰Be levels at 0, 3.37, 5.96, 7.37 and 9.5 MeV were observed (2001BO35). Additional measurements by (2001BO35) at E(¹⁵N) = 240 MeV observed known levels at 3.37, 5.96, 7.37 [u] + 7.54 [u], 9.27 [u] + 9.55, 10.5, 11.8 MeV [u = unresolved] and new levels at 13.6 ± 0.1, 15.3 ± 0.2, 16.9 ± 0.2 MeV with Γ = 200 ± 50 keV, 0.8 ± 0.2 MeV and 1.4 ± 0.3 MeV, respectively.

48. ¹³C(π⁺, 3p)¹⁰Be Q_m = 108.2216

The mechanism for π⁺ absorption on 2 and 3 nucleon clusters in targets ranging from Li to C was studied using pions at E_π⁺ = 50, 100, 140 and 180 MeV (1992RA11).

49. ¹³C(p, d + 2p)¹⁰Be Q_m = -29.9064

See ¹²C in (1990AJ01).

50. ¹³C(t, ⁶Li)¹⁰Be Q_m = -8.6187

Angular distributions were measured at E(³H) = 38 MeV (1989SI02). ¹⁰Be*(0, 3.36, 5.96) levels were observed and a DWBA analysis was used to extract spectroscopic factors shown in 10.17 (in PDF or PS). The results indicate that more strength goes to the ¹⁰Be excited states than shell model calculations predict.

51. ¹⁴C(¹⁴C, ¹⁸O)¹⁰Be Q_m = -5.79

See (1985KO04).

52. ¹⁴C(¹⁸O, ²²Ne)¹⁰Be Q_m = -2.34

At E(¹⁸O) = 102 MeV, a study of α-unbound states in ²²Ne indicated that ¹⁰Be*(0, 3.37) participate in the reaction (2002CU04).

53. (a) ¹²C, N, O, Mg, Al, Si, Mn, Fe, Ni, Au(p, ¹⁰Be)X
(b) C, ¹⁴N, ¹⁶O(n, ¹⁰Be)X

Astrophysical production of ¹⁰Be has been evaluated by measuring formation cross sections for protons incident on ¹⁶O and ²⁸Si at E_p = 30 - 500 MeV (1997SI29), on ¹²C at E_p = 40 - 500 MeV (2002KI19) and on O, Mg, Al, Si, Mn, Fe and Ni targets at E_p = 100 MeV - 2.6 GeV (1990DI13, 1990DI06, 1993BO41). The results of (1997SI29) suggest " soft solar proton spectrum with relatively few high energy protons over the last few million years" when compared with ¹⁰Be concentrations found in lunar rocks. See (1997BA2M, 1997GR1H, 1997MU1D, 1997ZO1C) for surveys of terrestrial ¹⁰Be concentrations, and see (2000NA34) for a model estimating ¹⁴N, ¹⁶O(p, ¹⁰Be) and (n, ¹⁰Be) cross sections for E_p = 10 MeV - 10 GeV and for discussion of various atmospheric transport models for distributing ¹⁰Be.

Spallation cross sections for E_p = 50 - 250 MeV protons on ¹⁶O were measured and were compared with Monte Carlo predictions from MCNPX (1999CH50); these data are relevant, for example, for estimating secondary radiation induced in proton therapy treatments. The target mass dependence of the cross sections for formation of ¹⁰Be from E_p = 12 GeV proton induced spallation reactions on Al through Au targets was measured by (1993SH27). Overall, ¹⁰Be production cross sections are found to increase with increasing target mass.

For reaction (b), the ¹⁰Be production cross sections for neutron induced reactions on C, N and O targets were measured at E_n = 14.6 MeV by (2000SU23). See also (2000NA34).

54. (a) ¹²C(¹⁰Be, X)
(b) ²⁸Si(¹⁰Be, X)

At E(¹⁰Be) ≈ 30 MeV/A, the ¹⁰Be + ¹²C reaction was observed to populate various exit channels (2004AH02, 2004AS02). States at E_x = 9.6 ± 0.1 and 10.2 ± 0.1 MeV were observed in the ⁶He + α breakup channel. Cross sections were given for breakup channels populating ⁸Be*(0, 3.0) and ⁹Be*(2.43), and other cross section were given for the (n, p) charge exchange reaction and proton pickup reaction that populate ¹⁰B and ¹¹B, respectively.

For reaction (b), fragmentation of ¹⁰Be was measured on Si targets for E(¹⁰Be) = 20 - 60 MeV/A (1996WA27) and E(¹⁰Be) = 30 - 60 MeV/A (2001WA40). The total reaction cross section was found to be near 1.55 b in this energy region, and R_rms^total(¹⁰Be) ≈ 2.38 fm is deduced from the cross section data.

55. ²⁵²Cf ternary cold fission

The de-excitation of ¹⁰Be* nuclei formed in the ternary cold fission of ²⁵²Cf → ¹⁴⁶Ba + ⁹⁶Sr + ¹⁰Be*(3.37) yields γ-rays that are roughly 6 keV lower in energy (1998RA16) than expected from the accepted excitation energy of E_x = 3368.03 ± 0.03 keV. The absence of Doppler broadening suggests that the ¹⁰Be is formed and decays while in the potential well of the heavier Ba and Sr nuclei (1998RA16). A theoretical analysis of the reaction explains the observation as an anharmonic perturbation, which shifts the excitation energy lower (2000MI07).