
^{10}Be (1974AJ01)(See Energy Level Diagrams for ^{10}Be) 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 alphaparticle 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, 1972FA14, 1972FU1C, 1972KA1F, 1973KA1D). Other topics: (1968FA02, 1968FA1B, 1968JO1E, 1968NE1C, 1969SA1A, 1970FO1B, 1970PE18, 1971BA2Y, 1972AN05, 1972CA37, 1972PN1A, 1972ST1C, 1973BU20, 1973JU2A, 1973KU03, 1973MA48, 1973MU11). Groundstate properties: (1968FA02, 1968FA1B, 1972ST1C, 1973SA30).
The halflife is (1.6 ± 0.2) × 10^{6} y (1972EM01), (1.7 ± 0.4) x 10^{6} y (1972MC26) and (1.5 ± 0.3) × 10^{6} y (1972YI01): we adopt τ_{1/2} = (1.6 ± 0.2) × 10^{6} y: log ft = 13.42 (B. Zimmerman and G. Fox, private communication). The spectrum is of the D_{2} type (1950WU1A). For a discussion of astrophysical and nuclear chronology considerations see (1972YI01). See also (1969VA1C, 1970WA11; theor.) and (1966BR1N).
The yield of γ_{0} and γ_{1} (to ^{10}Be*(0, 3.4)) has been studied at 90° for E_{t} = 0.5 to 3.0 MeV. The γ_{1} yield shows a peak at E_{t} = 1.85 MeV, Γ_{lab} ≈ 0.5 MeV. The γ_{0} 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 ^{9}Li and ^{8}Li (reactions (c) and (d)) have been studied from threshold to E(^{7}Li) = 21 MeV (1970CH1Q) and E_{t} = 6.5 MeV (1973AB10). A sharp minimum is observed in the ^{9}Li yield at E(^{7}Li) ≈ 13.6 MeV (1970CH1Q) and E_{t} = 5.62 MeV (1973AB10). It may correspond to a T = 2 state in ^{10}Be at E_{x} = 21.2 MeV, Γ_{c.m.} = 0.4 MeV (1970CH1Q, 1973AB10). For reaction (e) see (1966LA04). See also ^{6}He, ^{8}Li, ^{9}Li and ^{9}Be.
Angular distributions of the p_{0} and p_{1} groups have been measured at E_{α} = 30 MeV (1960KL03, 1972ME07). See also (1966LA04).
Angular distributions are reported for E(^{7}Li) = 2.1 to 5.75 MeV (1969CA1A; α_{1}, α_{2+3+4+5}), 3.5 to 5.75 MeV (1969CA1A; α_{0}) and 30.3 MeV (1971GL07; αgroups to ^{10}Be*(0, 3.4, 6.0, 7.4, 9.4, 10.7, 11.9, 17.9)). (1971GL07) also report an αgroup corresponding to ^{10}Be*(18.8). See also (1970OG1A), (1966RO1E; theor.) and ^{14}C 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 (1968FO1A) 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 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 (1971FO1A), 13.70 to 14.60 MeV (1968HU1E, 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 ^{9}Be. 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 ^{10}Be*(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 ^{10}Be*(5.960, 6.26). There is also indication of interference with swave 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 n_{0} 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 ^{10}Be*(9.27) (1966SC16). The polarization of the n_{0} group has also been studied at E_{n} = 4 MeV (1967GO1G). 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.).
Data on nonelastic cross sections are summarized by (1964ST25). The processes involved include (n, 2n) and (n, n')^{9}Be* → n + ^{8}Be; the (n, α) process is relatively weak. The total nonelastic 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, ^{9}Be(n, n')^{9}Be*(2.4) accounts for about half of the nonelastic 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 ^{9}Be(n, n')^{9}Be*(2.4) → n + ^{8}Be) and then sharply, reaching a plateau with a value ≈ 580 mb at 6.40 MeV (1969HO45, 1972BL1H). See also (1968EA1B). See also (1966LA04), (1966JE1B) and (1966FE04, 1967RO1E, 1967SA1F, 1968GR1F, 1969MA39, 1969PR17, 1971AL1E).
See (1966LA04, 1972ED01) and (1970BA1L).
The cross section for the (n, d) reaction has been measured for E_{n} = 16.3 to 18.7 MeV (1969SC05).
See (1966JE1B, 1966LA04) and (1972BI1E).
The cross section for production of ^{6}He 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 α_{0} transition is 11.7 ± 1.8 mb (1967PA03). See also (1966JE1B, 1966LA04) and (1970BA1L).
At E_{p} = 185 MeV the π^{+} spectrum shows groups corresponding to ^{10}Be*(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 ^{10}C 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; p_{0}), (1973SA1Q: 0.9 to 3.1 MeV; p_{0}, p_{1}), (1969RO12: 2.8 MeV; p_{0}, p_{1} and p to ^{10}Be*(5.958, 5.960)), (1970PO03: 4.50 to 6.0 MeV; p_{0}, p_{1}), (1964SC12, 1967SC29: 11.8 MeV; p_{0}, p_{1}) and (1969AR1B: 15 MeV; p_{0}). The angular distributions show l_{n} = 1 transfer for ^{10}Be*(0, 3.37, 5.958), l_{n} = 0 transfer for ^{10}Be*(5.960, 6.26) and l_{n} = 2 transfer for ^{10}Be*(7.37). ^{10}Be*(6.18, 7.54) are also populated. See (1954JU23, 1969RO12) and Table 10.4 (in PDF or PS) in (1966LA04). Attempts to understand the γdecay of ^{10}Be*(5.96) and its population in ^{9}Be(n, γ)^{10}Be 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 ^{10}Be*(3.37) [it is the state fed in the ^{9}Be(n, γ) decay]; the higher state has J^{π} = 1^{} and goes mainly by a crossover to ^{10}Be_{g.s.}. Angular correlations measured with the γray detector located normal to the reaction plane (≡ angular distributions) lead to l_{n} values consistent with the assignments of 2^{+} and 1^{} for ^{10}Be*(5.9658, 5.9660) obtained from the character of the γdecay (1969RO12). ^{10}Be*(6.18) decays primarily to ^{10}Be*(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 ^{10}Be*(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 p_{0} and p_{1} 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 ^{11}B in (1975AJ02) and (1966LA04). See also (1968LA1F), (1966WA1C, 1967LE1F, 1967WA1C, 1967YO1C, 1968SC1E, 1969CO1H) and (1971JO22, 1972DZ06, 1973DO02; theor.).
The d_{0} group has been observed at E_{t} = 1.6 to 3.5 MeV (1967BI1E). See also (1969NA04) and ^{12}B in (1975AJ02).
Not reported.
See (1973TO05; theor.).
The angular distribution has been measured at E(^{18}O) = 16 and 20 MeV (1971KN05).
Angular distributions of the p_{0} and p_{1} 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 ^{10}Be*(3.4) γ / → ^{10}Be(0) transition is 23.8 e^{2} · fm^{4} (from a comparison of the angular distributions with DWBA predictions) (1970AU02).
Not reported.
Transitions to ^{10}Be*(3.4) from the upper region of the giant resonance in ^{11}B are reported to be about twice as intense as those from the lower region (1971PA10): see ^{11}B in (1975AJ02). Angular distributions of the p_{0} and p_{1} groups have been measured with E_{bs} = 18.5 MeV (1970SO03). See also (1969MU10).
The angular distribution of the d_{0} group has been measured at E_{n} = 14.4 MeV (1968MI10, 1971MI12).
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 ^{11}B in (1975AJ02).
Angular distributions have been obtained for the ^{3}He group to ^{10}Be(0) at E_{d} = 11.8 MeV (1967FI07) and at 22 MeV (1971ST05: also ^{3}He to ^{10}Be*(3.4)).
Angular distributions of α_{0} and α_{1} have been measured for E_{t} = 1.0 to 2.1 MeV (1969SI12).
Angular distributions of the groundstate transitions have been measured at E(^{14}N) = 41, 77 and 113 MeV (1971LI11). See also (1973SC1J) and (1973DE1U ; theor.).
At E(^{6}Li) = 80 MeV, ^{10}Be*(0, 3.37, 5.95 ± 0.05) are strongly populated. There is also some evidence for the excitation of ^{10}Be*(9.27 ± 0.1). Angular distributions have been measured to the first three of these states (1973CE1B).
See (1969BR1D).
See ^{14}C in (1976AJ04).
See (1969BR1D).
