
^{9}Be (1979AJ01)(See Energy Level Diagrams for ^{9}Be) GENERAL: See also (1974AJ01) and Table 9.2 [Table of Energy Levels] (in PDF or PS). Shell model: (1975KU27, 1975SC1K, 1977CA08, 1977JA14, 1978BO31). α and cluster models: (1974CH19, 1974GR42, 1974PA1B, 1975AB1E, 1975CH28, 1975KR1D, 1975RO1B, 1975SC1K, 1976ZA06, 1977DE1K, 1977HO1F, 1977OK01, 1977SE1D, 1978FO1J, 1978FO1G, 1978HO1E, 1978OK01, 1978OS01). Collective and deformed models: (1974BO25, 1976BR26, 1977CA08). Special levels: (1974IR04, 1974KU06, 1975CH28, 1975LI20, 1975WI1E, 1976IR1B, 1976ZA06, 1977CA08, 1977JA14, 1978BO31, 1978FO1G, 1978HO1E, 1978OK01, 1978OK1B). Electromagnetic transitions: (1974CH46, 1974HA1C, 1974KU06, 1974MU13, 1976KU07, 1977DO06, 1978KI08). Astrophysical questions: (1973CA1B, 1973SC1C, 1973SC1D, 1973TI1A, 1973TR1B, 1973WE1D, 1974AU1A, 1974BO1J, 1974BO1K, 1974RE1A, 1974RO1G, 1975CH1F, 1975LA1E, 1975ME1E, 1975PR1B, 1976AU1B, 1976AU1C, 1976BO1E, 1976BO1H, 1976BO1J, 1976CO1B, 1976EP1A, 1976FU1B, 1976GI1C, 1976HA1F, 1976PE1A, 1976RA1C, 1976RO1J, 1976RO12, 1976SI1C, 1976SI1D, 1976VI1A, 1977AU1B, 1977BO1F, 1977DR1C, 1977DW1A, 1977GA1C, 1977HA1L, 1977MA1H, 1977PR1D, 1977SC1D, 1977WE1D, 1978AU1C, 1978BY1A, 1978DW1A). Special reactions: (1975AR14, 1975FE1A, 1975KU01, 1975RA12, 1975RA14, 1975RA21, 1975ZE01, 1976BE1K, 1976BU16, 1976CH28, 1976FR05, 1976HI05, 1976LE1F, 1976MI13, 1976NA11, 1976OS04, 1976RA1C, 1976RO12, 1977AR06, 1977FE1B, 1977GE08, 1977GO07, 1977GR1D, 1977KU1D, 1977PR05, 1977ST34, 1977ST1G, 1977YA1B, 1978BA1J, 1978BI08, 1978DI04, 1978FA1D, 1978GE1C, 1978GR1F, 1978UN01, 1978WE1D). Muon and neutrino capture and reactions: (1974EN10, 1975CA1H, 1975CH22, 1975FE1B, 1975KN1C, 1976SH1H, 1977CA1E, 1977DO06, 1977MU1A, 1978DE15, 1978LE04). Pion capture and reactions: (1973AL1A, 1973AR1B, 1973BA1G, 1973GO41, 1973WI1A, 1974AM01, 1974CL04, 1974DI20, 1974GO04, 1974HU14, 1974KA07, 1974MI06, 1974SP1A, 1974ST1G, 1974TA18, 1975BA1L, 1975BA1G, 1975BU1A, 1975ER03, 1975HU1D, 1975NI1B, 1975RO1G, 1975TA1C, 1975VO1D, 1975YA02, 1976AB1B, 1976AL1F, 1976AS1B, 1976BA1P, 1976DO1D, 1976DU1B, 1976ED1A, 1976EN02, 1976HEZU, 1976KI1E, 1976PI1B, 1976RA1F, 1976TR1A, 1977AB09, 1977AL1C, 1977AN1D, 1977AP1A, 1977AR1F, 1977AS1D, 1977BA51, 1977BA1Q, 1977BA2D, 1977BE1V, 1977DE1F, 1977DE1G, 1977DE1H, 1977DE1J, 1977DO06, 1977FY1A, 1977HO1B, 1977MA35, 1977MC1E, 1977PI1C, 1977SC1F, 1977SH1C, 1977SP1B, 1977TE1A, 1978BA1L, 1978BO01, 1978ER1C, 1978GEZX, 1978KI08, 1978MI1D, 1978MO01, 1978OL1A, 1978SE1D, 1978TH1B, 1978ZE01). Kaon reactions and reactions involving other mesons: (1973GO41, 1975PO1C, 1976AB1B, 1976BO1K, 1976BR1G, 1976KI1E, 1977AN1D, 1977BA27, 1977BE1U, 1977PO1A, 1978AT01, 1978BR1G). Other topics: (1973DZ1A, 1974CH19, 1974IR04, 1974KU06, 1974MU13, 1975CH1E, 1975CH28, 1975KU27, 1975LI20, 1975SC1M, 1976BR26, 1976DA1D, 1976DA1E, 1976ES1A, 1976GA1C, 1976IR1B, 1976KU07, 1976MA04, 1977KO1K, 1977PO1A, 1978OS01). Ground state properties: (1974DE1E, 1974EN10, 1974KU06, 1974MU13, 1974PA1B, 1974SHYR, 1975BE31, 1975CH28, 1976BR26, 1976FU06, 1977BA2E, 1977MA35, 1977OK01, 1978AN07).
Q = +53 ± 3 mb (1978SHZM). The neutron spectroscopic factor of ^{9}Be is 0.42 ± 0.04 (1977LA11).
The 0° differential cross section for reaction (a) increases monotonically between E_{t} = 0.10 and 2.4 MeV (1960SE12, 1961VA43, 1962SE1A) except for a resonance at E_{t} = 1.875 MeV (^{9}Be* = 18.938). The excitation function for ^{8}Li (reaction (b)) increases monotonically for E_{t} = 0.275 to 1.000 MeV (1972CI05, 1972CI1C). In the range E_{t} = 2.0 to 6.8 MeV, a broad peak [Γ ≈ 1.3 MeV] is observed at E_{t} = 4.57 MeV [E_{x} = 20.73 MeV] (1973AB10). For reaction (c), (d) and (e) see (1966LA04). See also ^{8}Li and (1977SU1A).
Angular distributions of p_{0} have been measured at E_{α} = 10.2 to 14.7 MeV and at 30 MeV: see (1974AJ01). In a study of the inverse reaction [^{9}Be(p, α)^{6}Li] at 45 MeV, the spectroscopic factors for (^{6}Li + t) and (^{5}He + α) cluster structures in ^{9}Be are calculated to be 0.003 and 0.102, respectively (1972DE01, 1972DE02).
For E_{d} = 0.1 to 1.1 MeV, a resonance in the yield of capture γrays is observed at E_{d} = 362 ± 3 keV (1965WO01), 361 ± 2 keV (1965IM01), corresponding to ^{9}Be*(16.976) with Γ_{c.m.} < 0.47 keV. The small width of this state and its energy correspondence with ^{9}Li*(2.69) argue for T = 3/2 (1965WO01). The angular distribution of the γrays to ^{9}Be(0) is isotropic to within 7% (1965IM01). The branching ratios to ^{9}Be*(0, 1.7, 2.4, 2.8, 3.1, 4.7) are 100 / 11.8 ± 0.6 / 3.3 ± 0.7 / 13.3 ± 4.2 /  / 12.9 ± 1.3 (1971SC19). The E_{x} and Γ of ^{9}Be*(2.8, 4.7) are 2.82 and 1.7 MeV, and 4.64 and 0.95 MeV, respectively. The character of the decay suggests (1/2)^{} for the second T = 3/2 state [^{9}Be*(16.98)] and is consistent with J^{π} = (1/2)^{} for ^{9}Be*(2.8) (1971SC19).
The yield of neutrons has been measured for E_{d} = 0.2 to 19 MeV [see (1974AJ01)] and for 0.4 to 3.0 MeV (1975MC02; σ_{t}), 2.5 MeV (1974JO1C) and 14.8, 18 and 23 MeV (1977LO10). Resonances in the yield of neutrons are reported at E_{d} = 0.36, 0.68, 0.98 and (1.8) MeV: see Table 9.3 (in PDF or PS). Polarization measurements have been reported at E_{d} = 0.64 MeV and at 2.5 to 3.7 MeV: see (1974AJ01). See also (1975SE07, 1977SE09). The yield of αparticles has been studied for E_{d} = 0.2 to 3.0 MeV [see (1974AJ01)] and at E_{d} = 0.60 to 1.25 MeV (1973RO42: α_{1}). Resonances are observed at E_{d} = 0.75, 1.00 and 2.5 MeV: see Table 9.3 (in PDF or PS). At E_{d} = 1.0 MeV reaction (c) is dominated by sequential decay via ^{8}Be*(2.9) and ^{5}He_{g.s.}. There is evidence also for the involvement of ^{9}Be*(17.50): J = 3/2 is suggested (1973HE26). See also (1975DA15, 1978SP03). See also ^{5}He, ^{8}Be, (1975FO19; astrophysics) and (1974JO1C, 1975GO38, 1977GR1F, 1977LO10, 1977SA28; applications).
The yield of p_{0} has been measured for E_{d} = 0.29 to 0.78 MeV and the ^{8}Li yield for E_{d} = 0.4 to 7.0 MeV [see (1974AJ01)] and from threshold to 3.6 MeV (1974MCZS, 1975MC02: σ_{t}; also cross sections for p_{0} and p_{1}, from 0.5 MeV). The yield of ^{8}Li has also been measured for E_{d} = 0.61 to 1.95 MeV (1976SC14): resonances are displayed in Table 9.3 (in PDF or PS). The total cross section at the E_{d} = 0.77 MeV resonance is 181 ± 8 mb (1976SC14). For earlier values see (1974AJ01). The cross section at the 0.77 MeV resonance serves as normalization for the ^{7}Be(p, γ)^{8}B data and to calculations of the Sfactor, of interest in relation to the solar neutrino problem. See also (1976HA1J).
The elastic scattering [E_{d} = 0.4 to 1.8 MeV] shows a marked increase in cross section for E_{d} = 0.8 to 1.0 MeV (perhaps related to ^{9}Be*(17.30)) and a conspicuous anomaly at E_{d} = 1.0 MeV, due to pwave deuterons [^{9}Be*(17.50)]. The elastic scattering has also been studied for E_{d} = 1.0 to 2.6 MeV (1974LO10) and E_{d} = 10.0 to 12.0 MeV (1971BI11). See also ^{7}Li.
The cross section for reaction (a) rises steeply from threshold to 95 mb at E_{d} = 2.4 MeV and then more slowly to ≈ 165 mb at E_{d} = 4.1 MeV (1955MA20). The t_{0} yield curve (θ_{lab} = 155°) decreases monotonically for E_{d} = 10.0 to 12.0 MeV (1971ZA07). See also ^{6}Li. For reaction (b) see ^{6}He.
Observed proton groups are listed in Table 9.4 (in PDF or PS). The parameters for the particle and γdecay of observed states are displayed in Table 9.5 (in PDF or PS), and in Table 9.6 (in PDF or PS) (1976MC10). Angular distributions have been reported in the range E(^{3}He) = 0.9 to 10 MeV [see (1974AJ01)], at 1.0 to 2.5 MeV (1975BO55: p_{0}, p_{2}) and at 14 MeV (1976IR02: p_{0}). See also ^{10}B and (1973WE15, 1975ST16; theor.).
At E_{α} = 30 MeV d_{0}, d_{1} and d_{2} angular distributions have been measured (1972ME07). See also (1976LE1K).
Angular distributions of the α_{0} group have been measured at E(^{7}Li) = 3.78 to 5.95 MeV (1967KI03). See also (1974AJ01).
Not reported: see (1970LK1A; theor.).
^{9}Li decays by β^{} emission with τ_{1/2} = 178.3 ± 0.4 msec to ^{9}Be*(0, 2.43, 2.78): see reaction 1 in ^{9}Li, and Table 9.7 (in PDF or PS). ^{9}Be(2.43, 2.78) are neutron unstable. The probability that ^{9}Li decays to these two states is 0.35. The branching ratio for the ^{9}Be*(2.43) → ^{8}Be(0) + n decay is (6.4 ± 1.2)%. ^{9}Be*(2.78) decays mainly to ^{8}Be(0) + n. The assignment J^{π} = 1/2^{} to ^{9}Be*(2.78) derives from the nature of the ^{9}Li decay, and the large value of θ^{2}_{p} [0.48 ± 0.06] which is in agreement with the shell model prediction that the 1/2^{} state should decay mainly by pwave neutron emission to ^{8}Be(0): if J^{π} = 3/2^{} this decay branch should be small (1970CH07).
The photoneutron cross section has been measured from threshold to 320 MeV: see Table 9.6 (in PDF or PS) in (1966LA04) and (1974KN08, 1975KN03: 17 to 37 MeV; monoenergetic γ), (1973AN29, 1975HU03, 1977BU02, 1978BU01). A sharp peak occurs 6 keV above threshold (1967BE49) [but see discussion in (1968BA1C)] with σ_{max} = 1.6 mb. The cross section then decreases slowly to 1.2 mb at E_{γ} = 40 keV (1967BE49). From bremsstrahlung studies, peaks in the (γ, Tn) cross section are observed corresponding to E_{x} = 1.80 and 3.03 MeV (1975HU03) [see both (1973AN29, 1975HU03) for additional structures]. At higher energies, using monoenergetic photons, (1975KN03) [who also report (γ, n) + (γ, pn) and (γ, 2n)] find the (γ, Tn) cross section to be relatively smooth from E_{γ} = 17 to 37 MeV with weak structures which correspond to E_{x} = 17.1, 18.8, 19.9, 21.4, 22.4, 23.8 [ ± 0.2] MeV and 27 ± 0.5 MeV (broad). See also (1976BE1H). In the range E_{γ} = 18 to 26 MeV the integrated (γ, n_{0}) cross section is < 0.1 MeV · mb, that for (γ, n_{1}) = 2.4 ± 0.4 MeV · mb (1977BU02) and the combined integrated cross section for (γ, n) to ^{8}Be*(16.6) and (γ, α_{0}) to ^{5}He_{g.s.} is 13.1 ± 2 MeV · mb (1978BU01). The total absorption cross section has been measured for E_{γ} = 10 to 210 MeV: it rises to ≈ 5 mb at ≈ 21 MeV, decreases to about 0 at 160 MeV and then increases to ≈ 1.5 mb at 210 MeV (1974AH03, 1975AH06). (1969DO09) report an integrated cross section of 156 ± 15 MeV · mb for E_{γ} = 10 to 29 MeV and resonant structure at E_{γ} = 11.8, (13.5), 14.8, (17.3), (19.5), 21.0, (23.0) and (25.0) MeV (1969DO09). Fine structure is reported at E_{γ} = 20.47 ± 0.04 and 20.73 ± 0.04 MeV (1964TE04). The absorption coefficient of 6.418 MeV γrays is reported by (1975MO27). Double pair production by 6.6 MeV γrays has been observed by (1976RO1N): σ_{ππ}/σ_{π} = (1.8 ± 0.6) × 10^{5} [average of values from interaction with several different nuclei]. See also (1973VE12, 1975SC05), (1974BU1A, 1975AB1F, 1975BR1F, 1977DA1B), (1975FO19; astrophysics) and (1976KH1C, 1978OC1B, 1978OK1B; theor.).
The yield shows structure in the energy region corresponding to the ^{9}Be levels at 17  19 MeV (1962CL06) followed by the giant resonance at E_{γ} ≈ 23 MeV (1962CL06; σ = 2.64 ± 0.30 mb). (1966DE13) report structure attributed to eleven states of ^{9}Be with 18.2 < E_{x} < 32.2 MeV. Integrated cross sections have been obtained for each of these resonances, and over different energy intervals for protons leading to ^{8}Li*(0 + 0.98, 2.26 + 3.21, 9.0, 17.0) (1966DE13). Angular and energy distributions of photoprotons in various energy intervals have been studied by many groups: see (1974AJ01) and (1974GO04). See also (1974DO07, 1975MA1K, 1978DO02) and (1975AN1H; theor.).
The integrated cross sections are reported to be 1.0 ± 0.5 MeV · mb (E_{γ} = 21 → 33 MeV) for reaction (a) to ^{7}Li*(0 + 0.4) and 0.6 ± 0.3 MeV · mb (E_{γ} = 25 → 33 MeV) for reaction (b) to ^{6}Li(0). The total integrated cross section for [(γ, p) + (γ, pn) + (γ, d) + (γ, t)] is given as 33 ± 3 MeV · mb by (1966DE13), who also report resonances in the (γ, d) and (γ, t) cross sections corresponding to ^{9}Be*(26.0 ± 0.2) and ^{9}Be*(32.2 ± 0.3), respectively. See also (1974AJ01).
See (1977CR1C) and (1974AJ01).
< r^{2} >^{1/2} = 2.46 ± 0.11 fm, Q = 6.5_{0.6}^{+0.9} fm^{2}, b = 1.5_{0.2}^{+0.3} fm [b = oscillator parameter] (1973BE19); < r^{2} >^{1/2} = 2.519 ± 0.012 fm, Q = 6.4 ± 2.4 fm^{2} (1972JA10) and private communication to J.C. Bergstrom); < r^{2} >^{1/2}_{M} = 3.2 ± 0.3 fm; Ω = 6 ± 2 μ_{N} · fm^{2} [this value of the magnetic octupole moment implies a deformation of the average nuclear potential] (1975LA23; see also for calculations of (b)). The elastic scattering of electrons has been studied for E_{e} up to 700 MeV: see (1974AJ01). Magnetic elastic scattering gives indications of both M1 and M3 contributions (1965GR18, 1966RA29). See also (1973FE13). Inelastic scattering populates a number of levels: Table 9.8 (in PDF or PS) displays the parameters of the states. See also (1974TI05, 1975DI05). Electron bremsstrahlung has been measured at E_{e} = 1.0 and 2.0 MeV by (1968RE11). For reaction (b) see (1974AJ01). At E_{e} = 700 MeV the proton separation spectra are similar to those observed in (p, 2p) except for an upward shift in the excitation (1978NA05). See also (1977BE1Q, 1977TU1C: E_{e} = 500 MeV; observe a peak at E_{x} ≈ 25 MeV), (1973KU19: 1.184 GeV) and (1974AJ01). For reaction (d) see (1975GE12). For reaction (e) see (1977SH1C). See also (1974DE1E, 1975FA1A) and (1973GA19, 1973KE1B, 1974BE10, 1974KU06, 1975AB1E, 1976DU05, 1977KU12, 1977OK01, 1977OK1A, 1978OK01; theor.).
Population of ^{9}Be*(0, 1.7, 2.4, 3.1) and possibly ^{9}Be*(6.8) has been reported in this reaction: see (1974AJ01). For the neutron decay of these states see Table 9.5 (in PDF or PS). Angular distributions have been reported at E_{n} = 14 MeV [see (1974AJ01)], at 5.9, 10.1 and 14.2 MeV (1977DR09: n_{0}, n_{1+2+3+4}), and 14.1 MeV (1974HY01: n_{0}, n_{2}). See also (1974HO1E, 1975HO1F, 1976BI1B). For reactions (a) and (b) see also ^{10}Be. For reaction (c) see (1978RI02). See also (1976MC1E) and (1978BY1B, 1978BY1C; theor.).
Elastic and inelastic scattering angular distributions have been studied at many energies for E_{p} = 5 to 1000 MeV [see (1974AJ01)] and (1974YA1C: p_{0}(5.0, 6.0 MeV), p_{1}(5.2, 6.0 MeV), p_{2}(4.2 → 6.0 MeV)), (1977CO1G: p_{0}(35.2 MeV)) and (1976AL1G: p_{0}; 1 GeV). The elastic angular distributions show pronounced diffraction maxima characteristic of the optical model. See (1973MO01) for a discussion of optical model parameters. (1973VO02), in a coupled channels analysis, find that a quadrupoledeformed optical model potential with a deformation parameter β = 1.1 provides an improved description of the elastic data and a good fit to the p_{2} data. The structure corresponding to ^{9}Be*(1.7) is asymmetric: the line shape peaks 25^{+15}_{11} keV above the threshold for ^{8}Be + n (1970TU06). The population of ^{9}Be*(1.7) has been studied for E_{p} = 4.2 to 5.5 MeV: it is consistent with a scattering length of about 20 fm between a neutron and ^{8}Be. An anomaly at E_{p} = 5.1 MeV is attributed to FSI between n, p and ^{8}Be (1974YA05). The weighted mean of the values of E_{x} listed in (1974AJ01) is 2432 ± 3 keV. ^{9}Be*(3.1) has a width 250 ± 50 keV (1960SP08), J^{π} = 3/2^{+}, 5/2^{+}, E_{x} = 3.03 ± 0.03 MeV (1956BO18), 3.04 ± 0.05 MeV (1960SP08). Higher states are observed at E_{x} = 4.8 ± 0.2, 6.76 ± 0.06 [J^{π} = 1/2^{+}, 5/2^{+}, 7/2^{+} (but see below), Γ = 1.2 ± 0.2 MeV], 7.94 ± 0.08 (Γ ≈ 1 MeV), 11.3 ± 0.2 MeV (Γ ≈ 1 MeV), 14.4 ± 0.3 (Γ ≈ 1 MeV), 16.7 ± 0.3, 17.4 ± 0.3, 19.0 ± 0.4, 21.1 ± 0.5 and 22.4 ± 0.7 MeV [the five highest states are all broad] (1965HA17). (1965JA1A) reports for ^{9}Be*(2.4, 6.8) B(E2↑) = 49 ± 6 and 24 ± 4 fm^{4} and Γ(E2↓) = 0.0025 and 0.10 eV, respectively. The strong population of ^{9}Be*(2.4, 6.8) is consistent with the assumption that they have J^{π} = 5/2^{} and 7/2^{}, respectively, and are members of the ground state K = 3/2^{} band. See also (1966LA04). (1974BI14) have studied the elastic scattering at E_{p} = 25 MeV: a nonzero D (depolarization) is reported; its existence constitutes evidence of a nucleonnucleus spinspin interaction. On the other hand (1976MOZF: E_{pbar} = 32 MeV) find no evidence for a nonzero value of D in the transition to ^{9}Be*(2.4). See also (1977KI04, 1978FR1D), (1974LO1B), (1973WE15, 1974GU13, 1974GU1D, 1974JA1F, 1978BY1B, 1978BY1C, 1978WO13; theor.) and ^{10}B.
The summed proton spectrum (reaction (a)) shows two peaks with Q = 16.4 ± 0.3 and 25.4 ± 0.5 MeV, corresponding to removal of a pproton and an sproton respectively, and a third peak of uncertain assignment (perhaps due to unresolved states) with Q = 32.3 ± 0.6 MeV (1966TY01: E_{p} = 460 MeV). See also ^{8}Li and (1973MA67; theor.). For reaction (b) see (1974AJ01). Quasifree scattering of the incident protons by zeromomentum αparticle clusters is consistent with the data obtained at E_{p} = 26.0, 35.0, 46.8 and 57 MeV (1968RO19, 1972QU01). At E_{p} = 100 MeV (1977CO07, 1977RO02) find < S_{α} > = 0.45 ± 0.02 using DWIA analysis: this value is consistent with that predicted by a simple LS coupling shell model calculation. See also (1975RO1B, 1978CH1H) and (1975SA01; theor.). At E_{p} = 12.7 MeV, ^{9}Be*(3.05) is strongly populated and ^{9}Be*(4.70) is also observed in reaction (d) (1977JE01). See also Table 9.5 (in PDF or PS). (1978CH07), ^{8}Be (1977WA05; E_{p} = 45 and 47 MeV), (1974MI05, 1974YA05) and (1974AV02; theor.). See also (1974AJ01). In reaction (f), at E_{p} = 100 MeV, (1977CO07) find < S_{α} > = 0.47 ± 0.04.
Elastic angular distributions have been studied in the range 1.1 to 410 MeV [see (1974AJ01)] and at E_{d} = 1.0 to 2.2 MeV (1972LO05), E_{dbar} = 15 MeV (1976DA15; also d_{2}, d_{4}) and E_{d} = 27.98 MeV (1977OO01). Angular distributions to ^{9}Be*(2.4) have also been reported at E_{d} = 11.8, 14.35 and 15.8 MeV: see (1974AJ01). Inelastic groups have been reported to ^{9}Be*(1.7, 2.4, 3.1, 4.7, 6.8): see (1966LA04). (1968KR02) report E_{x} = 2431.9 ± 7.0 keV and 3040 ± 15 keV (Γ = 294 ± 20 keV). See also (1978LO1C), (1977TE1A) and (1974BO39, 1974CH58, 1974GU1D, 1977DM1A; theor.).
The angular distribution of elastically scattered tritons has been measured at E_{t} = 2.10 MeV (1969HE08, 1970CO04). Reaction (b) at E_{t} = 4.2 and 4.6 MeV proceeds via ^{9}Be*(2.4) (1967SE11).
Angular distributions of elastically scattered ^{3}He particles have been obtained at E(^{3}He) = 4 to 32.3 MeV [see (1974AJ01)], at E(^{3}He) = 1.6 to 2.4 MeV (1974BO38) and 32.6 MeV (1975BU11; polarized ^{3}He). See also (1975DA1A). At E(^{3}He) = 217 MeV (1973WI07, 1976WI05) angular distributions have been studied to ^{9}Be*(0, 2.4). For optical model parameters see discussions in (1972BU30, 1973WI07, 1976WI05). At E(^{3}He) = 39.8 MeV inelastic ^{3}He groups are observed to ^{9}Be*(1.7, 2.4, 3.1, 4.7, 6.8, 14.4) (1969BA06). See also (1976RO1L). In a study of reaction (b) the (^{5}He + α) system is found to be mainly in an Sstate: the probability of finding such a cluster in ^{9}Be is N_{eff} = 0.05 (1975KA05). See also ^{8}Be.
Elastic scattering has been studied at many energies for E_{α} = 8.76 to 104 MeV [see (1974AJ01)] and at 5.00 to 5.50 MeV (1973GO15). See (1972DE01, 1972DE02) for a discussion of optical model parameters. The structure (^{5}He + α) for ^{9}Be is found to be much more probable than (^{6}Li + t): the ratio of spectroscopic factors is about 30 (1972DE01, 1972DE02) . Inelastic groups have been observed to ^{9}Be*(1.7, 2.4, 3.1, 6.8, 11.3): see (1966LA04). The angular distribution of the α_{1} group to ^{9}Be*(1.7) is consistent with J^{π} = 1/2^{+} (1964LU02: E_{α} = 18.4 MeV). The angular distributions for α_{2} are consistent with l = 2 [J^{π} = (1/2, 5/2, 7/2)^{}] (1958SU14, 1967FU08). Analysis based on the rotational model leads to a deformation coefficient β_{2} = 0.34 ± 0.01 (1964GR39). The summed αspectra from reaction (b) show a peak corresponding to quasielastic scattering leaving ^{5}He in its ground state. The angular distribution peaks at the angle corresponding to zeromomentum αcluster. The probability of formation of such clusters is (7^{+13}_{5})% (1969PI11). See also (1977WA1M). (1976WO11) find S_{α} = 0.96. A study of continuum neutrons at E_{α} = 4.9 to 6.4 MeV (reaction (c)) indicates that sequential decay takes place via ^{9}Be*(1.7, 2.4, 3.1) (1972OB01). See also (1974AJ01, 1975RO1B) and (1974CH58, 1974KU15, 1974LO09, 1974PI11, 1976AV05, 1977DE1K, 1977DM1A, 1977MO11; theor.).
Elastic angular distributions have been measured at E(^{6}Li) = 4 and 6 MeV (1974VO06) and 24 MeV (1968DA20) and at E(^{7}Li) = 24 MeV (1972WE08) and 34 MeV (1977KE09).
Elastic angular distributions have been obtained at E = 5, 9, 12 and 16 MeV (1977YO02).
Elastic angular distributions are reported at E(^{12}C) = 12, 15, 18 and 21 MeV (1970BA49) and E(^{9}Be) = 14, 20 and 26 MeV (1978LA1G) and 43 MeV (1977MA1L). The neutron spectroscopic factor for ^{9}Be is 0.84 (1970BA49). For spallation studies see (1977IG1D, 1978CH02). See also (1976ECZZ, 1977PE1B, 1978MA1L), (1978EN06) and (1978PA1B; theor.).
Elastic angular distributions have been measured at E(^{14}N) = 25 (1966OE1A) and 27.3 MeV (1959HA28).
Elastic angular distributions have been reported at E(^{16}O) = 15, 18, 21.5 and 25 MeV (1970BA49), 25.7 to 29.5 MeV (1975FU05) and 30 MeV (1969KR03), and at E(^{18}O) = 12.1, 16 and 20 MeV (1971KN05). See also (1974TA1C, 1978CH02), (1978EN06) and (1978PA1B; theor.).
Elastic angular distributions have been measured at E(^{9}Be) = 14, 20 and 26 MeV for reactions (a), (b) and (c) (1977BA71) and at 14 and 17 MeV for reaction (c) (1977EC04). See also (1978DE1M) and (1978EN06).
Forward angular distributions have been obtained at E_{d} = 15.0 MeV for the tritons to ^{9}Be*(0, 1.7, 2.4, 3.1). The ground state transition is well fitted by l = 1. The transition to ^{9}Be*(1.7) [Γ ≈ 165 ± 25 keV] is consistent with J^{π} = 1/2^{+}, that to ^{9}Be*(2.4) is quite well fitted with l = 3 [J^{π} = 5/2^{}], and that to ^{9}Be*(3.1) [Γ = 280 ± 25 keV] is consistent with l = 2. No other narrow states are seen up to E_{x} = 5.5 MeV (1970AU02).
See reactions 24 and 26 in^{10}B.
A good fit to the angular distributions of the deuterons to ^{9}Be*(0, 2.4) has been obtained at E_{n} = 14.4 MeV, using DWBA. The spectroscopic factors are in close agreement with shell model predictions (1965VA05). See also ^{11}B in (1980AJ01).
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 ^{10}B.
Angular distributions of the ^{3}He groups corresponding to ^{9}Be*(0, 2.4) have previously been measured at E_{d} = 11.8 and 28 MeV: see (1974AJ01). Recent angular distribution measurements at E_{dbar} = 15 MeV (1974LU06; to ^{9}Be*(0, 2.4)) and at E_{d} = 52 MeV (1975SC41; to ^{9}Be*(0, 2.4, 6.7)) lead to S = 0.72 and 0.82 (1974LU06) and relative S = 1.00, 0.98 and 0.58 (1975SC41). In the latter experiment ^{9}Be*(11.3) appears also to be strongly populated. The data for ^{9}Be*(0, 2.4) are very similar, as predicted, to those obtained in the mirror reaction: see reaction 12 in ^{9}B. See also (1974DA1D; theor.) and ^{12}C in (1980AJ01).
At E_{t} = 12.9 MeV αgroups are observed to the ground state of ^{9}Be and to excited states at E_{x} = 1.75 ± 0.03, 2.43, 3.02 ± 0.04 (Γ = 320 ± 60 keV), 11.27 ± 0.04 (Γ = 530 ± 70 keV), (14.4) [Γ ≈ 800 keV], 14.39 and 16.67 MeV. The T = 3/2 state ^{9}Be*(14.39) is very weakly populated [≈ 5% of intensity of α_{2}]. The angular distribution of the α_{2} group shows sharp forward and backward peaking. The α_{0} group is not peaked in the backward direction (1968AJ01). A study at E_{t} = 1.0 to 3.2 MeV finds E_{x} = 1.750 ± 0.025 MeV, Γ = 220 ± 8 keV. The angular distribution of the corresponding αgroup has been determined at E_{t} = 2.5 MeV (1971GE09). See also (1977CI1A) and ^{13}C in (1981AJ01).
See (1977KO27).
The ground state angular distribution has been measured at E(^{14}N) = 27.5 MeV (1962NE01).
See (1968OK06).
The angular distribution of t_{0} has been measured at E_{n} = 14.4 MeV (1970MI14).
At E_{p} = 45 MeV angular distributions are reported for the ^{3}He ions corresponding to ^{9}Be*(0, 2.4, 11.8, 13.8, 14.39 [T = 3/2], 15.96 ± 0.04 [T = 1/2]). In addition one or more states may be located at ^{9}Be*(15.13). It is suggested that ^{9}Be*(11.8, 13.8, 15.96) are the J^{π} = 3/2^{}, T = 1/2 analogs to ^{9}B*(12.06, 14.01, 16.02) (1971HA10). Angular distributions are also reported at E_{p} = 40 MeV (1971KA21: α_{0}, α_{2}). The intensity of the group to ^{9}Be*(3.1) is ≈ 1% of the ground state group (1971KA21). The excitation energy of the first T = 3/2 state is E_{x} = 14392.6 ± 1.8 keV (1974KA15) using the (1977WA08) mass for ^{9}Be_{g.s.}. For reaction (b) see (1964BA1C).
Alpha groups are reported corresponding to ^{9}Be*(0, 1.7, 2.4, 3.1). The width of ^{9}Be*(1.7) [E_{x} = 1.70 ± 0.01 MeV (1975FO13)] is Γ_{c.m.} = 224 ± 25 (1958KA31, 1966PU02), 200 ± 10 keV (1975FO13). The weighted mean of the values of E_{x} of ^{9}Be*(2.4), reported in (1974AJ01), is 2425 ± 3 keV. The 5/2^{+} state is at E_{x} = 3.02 ± 0.03 MeV (1955LE36), 3.05 ± 0.03 MeV (1956BO18): Γ_{c.m.} = 257 ± 25 keV (1958KA31, 1966PU02). The ratio Γ_{γ}/Γ of ^{9}Be*(1.7) ≤ 2.4 × 10^{5}, that for ^{9}Be*(2.4) is (1.16 ± 0.14) × 10^{4} (1966PU02). Since Γ_{γ} is known from (e, e') [see Table 9.8 (in PDF or PS): 0.089 ± 0.010 eV], Γ = 0.77 ± 0.15 keV. Angular distributions for α_{0} and α_{2} are reported at E_{d} = 0.39 to 2.5 MeV and at 12 MeV [see (1974AJ01)] and at 3.0 to 3.9 MeV (1974CA34, 1975CA1J, 1975CA1K). Reaction (b), at E_{d} = 10.4 and 12.0 MeV, proceeds via ^{9}Be*(2.4) and to some extent via ^{9}Be*(3.1, 4.7) and possibly some higher excited states. The dominant decay of ^{9}Be*(2.4) is to ^{5}He(0) + α while ^{9}Be*(3.1, 4.7) decay to ^{8}Be(0) + n (1971RE19). It should be noted, however, that the peaks corresponding to ^{9}Be*(3.1) have a FWHM of ≈ 1 MeV, which may imply that ^{9}Be*(2.8) is involved (1971RE19). See also (1978GR07) and ^{13}C in (1981AJ01).
See (1968OK06).
Angular distributions of the α_{0} group have been measured at E_{n} = 13.9 to 18.8 MeV; ^{9}Be*(1.7, 2.4, 3.1) are also populated: see (1974AJ01). Reaction (b) at E_{n} = 13 to 18 MeV involves ^{9}Be*(2.4) (1966MO05). See also (1975AN01, 1976AN16), (1973PE19; theor.) and ^{12}C in (1980AJ01), and ^{13}C in (1981AJ01).
Angular distributions have been obtained for the transition to ^{7}Be*(0, 0.43) + ^{9}Be_{g.s.} (1972RU03: 42 MeV).
See (1975RA13; theor.).
See (1974BA15).
See ^{13}C in (1981AJ01).
See (1975OB01) and ^{14}N in (1981AJ01).
See (1966DE09).
Angular distributions have been obtained at E(^{3}He) = 70 MeV for the transitions to ^{9}Be*(0, 2.4) and ^{7}Be*(0, 0.43). Broad states at 2.9, 4.8 ± 0.2, 7.3 ± 0.2 and 11.9 ± 0.4 MeV are also populated (1976ST11).
At E_{α} = 65 MeV angular distributions have been measured for the transitions to ^{9}Be*(0, 2.4) (1976WO11).
See (1974CH1Q) and (1978EN06).
See (1974BA15) and (1978EN06).
See (1972RU03).
