(See Energy Level Diagrams for 10Be)
Cluster and alpha-particle model: (1973KU03).
Special reactions: (1967KO1F, 1967SH1B, 1968YI01, 1969AR13, 1969GA18, 1969GO1H, 1969YI1A, 1971AR02, 1971LE33, 1971RA1K, 1972AM04, 1972PN1A, 1972SI1G, 1972VO06, 1973KO1D, 1973KU03, 1973LA19, 1973VO1G, 1973WI15).
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 τ1/2 = (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).
The yield of γ0 and γ1 (to 10Be*(0, 3.4)) has been studied at 90° for Et = 0.5 to 3.0 MeV. The γ1 yield shows a peak at Et = 1.85 MeV, Γlab ≈ 0.5 MeV. The γ0 yield peaks near the same energy but with a width Γlab ≈ 1.5 MeV (1973BL1B).
The yields of 9Li and 8Li (reactions (c) and (d)) have been studied from threshold to E(7Li) = 21 MeV (1970CH1Q) and Et = 6.5 MeV (1973AB10). A sharp minimum is observed in the 9Li yield at E(7Li) ≈ 13.6 MeV (1970CH1Q) and Et = 5.62 MeV (1973AB10). It may correspond to a T = 2 state in 10Be at Ex = 21.2 MeV, Γc.m. = 0.4 MeV (1970CH1Q, 1973AB10).
Angular distributions are reported for E(7Li) = 2.1 to 5.75 MeV (1969CA1A; α1, α2+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).
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).
The older cross section data is summarized in (1964ST25). More recent measurements of the total cross section are reported for En = 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 En = 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 En = 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 En = 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, Jπ = 3+ state (1964LA04). The structure at En = 2.73 MeV is ascribed to two levels: a broad state at about 2.85 MeV with Jπ = 2+, and a narrow one, Γ ≈ 100 keV, at En = 2.73 MeV with a probable assignment of Jπ = 4- (1951BO45, 1966SC16). The 4- assignment results from a study of the polarization of the n0 group at En = 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 En = 4 MeV (1967GO36). See also (1966DA1B). A weak dip at En ≈ 4.3 MeV is ascribed to a level with J ≥ 1 (1961FO07).
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 En = 5.2 MeV (1968EA1B). The cross section is ≈ 600 mb at En = 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 En = 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).
The cross section for the (n, d) reaction has been measured for En = 16.3 to 18.7 MeV (1969SC05).
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 En = 2.7 MeV (1957ST95). From En = 3.9 to 8.6 MeV, the cross section decreases smoothly from 100 mb to 32 mb (1961BA53). At En = 14.4 MeV, the total cross section for the α0 transition is 11.7 ± 1.8 mb (1967PA03). See also (1966JE1B, 1966LA04) and (1970BA1L).
At Ep = 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).
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 ln = 1 transfer for 10Be*(0, 3.37, 5.958), ln = 0 transfer for 10Be*(5.960, 6.26) and ln = 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 Jπ = 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 Jπ = 1- and goes mainly by a crossover to 10Beg.s.. Angular correlations measured with the γ-ray detector located normal to the reaction plane (≡ angular distributions) lead to ln 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): Eγ = 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 p3/2 for transfer of a neutron with angular momentum 3/2 have been determined for the p0 and p1 groups using vector polarized deuterons with Ed = 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 (1973TO05; theor.).
The angular distribution has been measured at E(18O) = 16 and 20 MeV (1971KN05).
Angular distributions of the p0 and p1 groups have been measured at Ep = 12.0 to 16.0 MeV. The elastically scattered deuterons have been studied at Ed = 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).
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 Ebs = 18.5 MeV (1970SO03). See also (1969MU10).
See (1969BA1F; theor.).
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).
Angular distributions of α0 and α1 have been measured for Et = 1.0 to 2.1 MeV (1969SI12).
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).
See 14C in (1976AJ04).