(See Energy Level Diagrams for 9Be)
Complex reactions involving 9Be: (1978BE1G, 1978BH03, 1978DU1B, 1978HE1C, 1979AL22, 1979BA10, 1979BA34, 1979BO22, 1979BU1G, 1979DY01, 1979FR12, 1979GA04, 1979GE1A, 1979JA1C, 1979LO11, 1979SA17, 1979SA27, 1979SA1E, 1979SC08, 1979SC1D, 1979VI05, 1979WE06, 1980BR1P, 1980GR10, 1980ME1F, 1980MI01, 1980MO28, 1980WI1L, 1981BH02, 1981BL1G, 1981CI03, 1981HN02, 1981LE03, 1981ME13, 1981MO20, 1981TA16, 1981TA22, 1982BO1J, 1982BO35, 1982GU1H, 1982JA1C, 1982LU01, 1982LY1A, 1982MO1N, 1982WU1B, 1983FU04, 1983SA06).
Reactions involving pions (See also reaction 17): (1978AR1J, 1978ER1A, 1978FU09, 1978GE11, 1978KI13, 1978VL1B, 1978WA1B, 1979AL1J, 1979BA16, 1979BO21, 1979BO1N, 1979BU1D, 1979CO1D, 1979DE06, 1979DE1G, 1979FR1F, 1979FU1G, 1979GI1B, 1979GI1C, 1979HO13, 1979HOZS, 1979IN1A, 1979KI1G, 1979MA02, 1979MA1P, 1979NA1E, 1979OH1A, 1979PE1D, 1979PI1C, 1979SC1E, 1979ST1G, 1979TI1A, 1979WI1E, 1980BU15, 1980CR03, 1980ER01, 1980HA29, 1980JE1C, 1980LE02, 1980MA1F, 1980NA1D, 1980NA1L, 1980NI03, 1980ST15, 1980TH1C, 1980TR1A, 1981AS1H, 1981BA2M, 1981BA2R, 1981BE13, 1981BE1X, 1981BE63, 1981BO06, 1981DU1H, 1981FE2A, 1981GE03, 1981IO01, 1981IS11, 1981KU15, 1981LE14, 1981MC09, 1981NA05, 1981NI03, 1981SEZR, 1981WA1H, 1981YA1A, 1982AP1A, 1982AS01, 1982GR1F, 1982MU1C, 1983AS02).
Reactions involing kaons and other mesons: (1978AN1B, 1978DA1A, 1978SO1A, 1979GA1E, 1979LI1A, 1980AU1C, 1980BE30, 1980BE12, 1980DE11, 1980DO1E, 1980GA1C, 1980PO1A, 1981BA2N, 1981BE17, 1981BE45, 1981BO09, 1981DA1C, 1981HU1C, 1981KA1U, 1981PO1D, 1981WA1H, 1981ZH1C, 1982AB07, 1982BA17, 1982BO1U, 1982DEZQ, 1982DO1C, 1982ER1E, 1982PI1J, 1982PO1C).
Hypernuclei: (1977KO1D, 1978DA1A, 1978PO1A, 1978SO1A, 1979GA1E, 1979VE1B, 1980AU1C, 1980BE30, 1980BE12, 1980DO1E, 1980GA1P, 1980GI1C, 1980PO1A, 1980ZH1C, 1980ZO1A, 1981BA2N, 1981BE17, 1981BE45, 1981BO09, 1981DA1C, 1981DA1D, 1981PO1D, 1981PO1F, 1981RE1B, 1981ST1G, 1981SU1D, 1981WA1J, 1982BA1P, 1982BA17, 1982BO1U, 1982DA1R, 1982DEZQ, 1982DO1C, 1982DO1M, 1982ER1B, 1982ER1E, 1982GA1J, 1982IK1A, 1982JO1C, 1982KO11, 1982MO1Q, 1982PO1C, 1982SH1P, 1982ZH1F, 1983BA2K, 1983JO1E).
Q = +53 ± 3 mb: see (1978LEZA).
The 0° differential cross section for reaction (a) increases monotonically between Et = 0.10 and 2.4 MeV except for a resonance at Et = 1.875 MeV (9Be* = 18.937). The excitation function for 8Li (reaction (b)) increases monotonically for Et = 0.275 to 1.000 MeV. In the range Et = 2.0 to 6.8 MeV, a broad peak [Γ ≈ 1.3 MeV] is observed at Et = 4.57 MeV [Ex = 20.73 MeV]: see (1974AJ01) for references. For reaction (d) see (1982CE1C). Cross sections for 7Be production [reaction (f)] (Et = 4.4 to 11.99 MeV) are reported by (1980GU26). For reactions (c) and (e) see (1966LA04).
For Ed = 0.1 to 1.1 MeV, a resonance in the yield of capture γ-rays is observed at Ed = 361 ± 2 keV, corresponding to 9Be*(16.975) with Γc.m. < 0.47 keV. The small width of this state and its energy correspondence with 9Li*(2.69) argue for T = 3/2. The angular distribution of the γ-rays to 9Be(0) is isotropic to within 7%: see (1974AJ01) for references.
The yield of neutrons has been measured for Ed = 0.2 to 23 MeV: observed resonances are displayed in Table 9.3 (in PDF or PS). For polarization measurements [Ed = 0.64 MeV and 2.5 to 3.7 MeV] see (1974AJ01). See also (1979SE04; theor.).
The yields of α-particles have been measured for Ed = 0.25 to 0.75 MeV (1977RO1C; α1) and 0.2 to 3.0 MeV: see Table 9.3 (in PDF or PS). For reaction (c) see (1974AJ01) and 5He. The 7Be production cross section (reaction (d)) has been studied for Ed = 5.38 to 11.94 MeV (1980GU26). See also (1978BA1F, 1979JO1B; applications).
Excitation functions have been measured for Ed = 0.29 to 7 MeV [see (1974AJ01, 1979AJ01)] and 0.60 to 1.2 MeV (1982EL03, 1982FI03; σt) and 0.7 to 3.4 MeV (1979MI1E; σt): observed resonances are displayed in Table 9.3 (in PDF or PS). Recent measurements of the total cross section at the Ed = 0.78 MeV resonance are 181 ± 8 mb (1976SC14), 174 ± 16 mb (1979MI1E), 146 ± 13 mb (1982EL03) and 148 ± 12 mb (1982FI03): we adopt 147 ± 9 mb. See also (1983FI01). For earlier values see (1974AJ01). This cross section serves as normalization for the 7Be(p, γ)8B data and to calculations of the S-factor. The new value predicts that the neutrino-capture rate in 37Cl should be decreased by about 15%.
The elastic scattering [Ed = 0.4 to 1.8 MeV] shows a marked increase in cross section for Ed = 0.8 to 1.0 MeV (perhaps related to 9Be*(17.30)) and a conspicuous anomaly at Ed = 1.0 MeV, due to p-wave deuterons [9Be*(17.50)]. The elastic scattering has also been studied for Ed = 1.0 to 2.6 MeV and 10.0 to 12.0 MeV: see (1979AJ01). See also (1982AB1D) and 7Li.
The cross section for reaction (a) rises steeply from threshold to 95 mb at Ed = 2.4 MeV and then more slowly to ≈ 165 mb at Ed = 4.1 MeV. The t0 yield curve (θlab = 155°) decreases monotonically for Ed = 10.0 to 12.0 MeV: see (1974AJ01). See also 6Li. For reaction (b) see 6He.
Observed proton groups are listed in Table 9.4 (in PDF or PS). The parameters for the particle and γ-decay of observed states are displayed in Tables 9.5 (in PDF or PS) and 9.6 (in PDF or PS). Angular distributions have been reported in the range E(3He) = 0.9 to 14 MeV: see (1974AJ01, 1979AJ01). See also (1981SL03), (1981VI1B) and 10B.
The γ-decay of 9Be*(14.39) [Jπ = 3/2-; T = 3/2] has been measured by (1978DI08) and compared with the decay from the mirror state in 9B: see Table 9.6 (in PDF or PS). No evidence is found for violation of the selection rule for ΔT = 1 mirror γ transitions (1978DI08).
Angular distributions of α0 have been studied at E(7Li) = 3.78 to 5.95 MeV: see (1974AJ01).
9Li decays by β- emission with τ1/2 = 178.3 ± 0.4 msec to several 9Be states: see (reaction 1 in 9Li and Table 9.7 (in PDF or PS). Measurement of β-α coincidences involving 9Be*(11.28) show contributions from the direct n + 2α breakup process as well as the sequntial n-emission to 8Be*(2.9) [Jπ = 2+], followed by breakup into 2α (1981LA11, 1981NY1A). The branching ratio fop the 9Be*(2.43) → 8Beg.s. + n decay is (6.4 ± 1.2)%. 9Be*(2.78) [Jπ = 1/2-] decays mainly to 8Beg.s. + n presumably by p-wave neutron emission: see (reaction 13 in (1979AJ01). See also (1981JOZV) and (1979DE15; theor.).
The photoneutron cross section has been measured from threshold to 320 MeV: see Table 9.6 (in PDF or PS) in (1966LA04) and (1979AJ01). A pronounced peak occurs ≈ 29 keV above threshold with σmax = 1.33 ± 0.24 mb. The shape of the resonance has been measured very accurately for Eγ = 1675 to 2168 keV. The FWHM of the peak is estimated to be 100 keV (1982FU11). See also (1983BA52; theor.). The cross section then decreases slowly to 1.2 mb at 40 keV above threshold. From bremsstrahlung studies, peaks in the (γ, Tn) cross section are observed corresponding to Ex = 1.80 and 3.03 MeV. At higher energies, using monoenergetic photons, the (γ, Tn) cross section is found to be relatively smooth from Eγ = 17 to 37 MeV with weak structures which correspond to Ex = 17.1, 18.8, 19.9, 21.4, 22.4, 23.8 [± 0.2] MeV and 27 ± 0.5 MeV (broad). In the range Eγ = 18 to 26 MeV the integrated (γ, n0) cross section is < 0.1 MeV · mb, that for (γ, n1) = 2.4 ± 0.4 MeV · mb and the combined integrated cross section for (γ, n) to 8Be*(16.6) and (γ, α0) to 5Heg.s. is 13.1 ± 2 MeV · mb.
The total absorption cross section has been measured for Eγ = 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. An integrated cross section of 156 ± 15 MeV · mb is reported for Eγ = 10 to 29 MeV as is resonant structure at Eγ = 11.8, (13.5), 14.8, 917.3), (19.5), 21.0, (23.0) and (25.0) MeV. Fine structure is also reported at Eγ = 20.47 ± 0.04 and 20.73 ± 0.04 MeV. See (1979AJ01) for references. See also (1978CH1E, 1979ZI1A, 1980AH1A, 1982DE1H), (1982BA1T; applications) and (1979BA60, 1979KI1D, 1980TA1D, 1981DE18, 1981DE33, 1981IS11; theor.).
The yield shows structure in the energy region corresponding to the 9Be levels at 17 - 19 MeV followed by the giant resonance at Eγ ≈ 23 MeV (σ = 2.64 ± 0.30 mb). Structure attributed to eleven states of 9Be with 18.2 < Ex < 32.2 MeV has also been reported. Integrated cross sections have been obtained for each of these resonances, and over different energy intervals for protons leading to 8Li*(0 + 0.98, 2.26 + 3.21, 9.0, 17.0). Angular and energy distributions of photoprotons in various energy intervals have been studied by many groups: see (1974AJ01) for references. See also (1976MA34). For momentum spectra using tagged photons with Eγ = 180 - 420 MeV and 360 - 600 MeV, see (1980HO22) and (1982BA32), respectively. See also (1981AR04, 1981TA1T, 1983ST1G).
The integrated cross sections are reported to be 1.0 ± 0.5 MeV · mb (Eγ = 21 → 33 MeV) for reaction (c) to 7Li*(0 + 0.4) and 0.6 ± 0.3 MeV · mb (Eγ = 25 → 33 MeV) for reaction (d) to 6Li(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 9Be*(26.0 ± 0.2) and 9Be*(32.2 ± 0.3), respectively. See also (1974AJ01), (1980IS10, 1982AV06, 1983HO01, 1983LIZN) and (1981IS11, 1982SU09; theor.).
b = 1.5+0.3-0.2 fm [b = oscillator parameter],
< r2 > 1/2M = 3.2 ± 0.3 fm, Ω = 6 ± 2 μN · fm2 [this value of the
magnetic octupole moment implies a deformation of the average nuclear potential].
The elastic scattering of electrons has been studied for Ee up to 700 MeV. Magnetic elastic scattering gives indications of both M1 and M3 contributions. See also (1978DE32). Inelastic scattering populates a number of levels: Table 9.8 (in PDF or PS) displays the parameters of the states. See (1974AJ01, 1979AJ01) for other work and for references.
At Ee = 134.7 and 237 MeV (1979BU11) have determined transverse and longitudinal form factors for electrodisintegration in the region of the quasielastic scattering peak. They report the observation of E1 and E2 giant resonance peaks: see Table 9.8 (in PDF or PS). The quasielastic process has been studied in the range 250 - 580 MeV/c by (1978KU06). For reaction (c) see 8Li. For reaction (e) see (1980ST15). (1979JE04) have measured the ratio π-/π+ in the electroproduction of 10 MeV pions. See also (1979SC1E) and the "General" section here.
See also (1979FR1B, 1979FR1F, 1979FR1C, 1983LIZO), (1979MO1G, 1979TI1A, 1980MO1C, 1981MO1H, 1982DE1J) and (1978KE13, 1978TA1D, 1979OK02, 1980ER01, 1980FU1G, 1980SA1E, 1980ST15, 1981BO1T, 1981CH30, 1981DE1T, 1981IS11, 1981KE15, 1981LA1E, 1982BO1G, 1982KE1C, 1983BO1E, 1983OC01; theor.).
The elastic scattering, and inelastic scattering to 9Be*(2.43, 6.76), have been studied at Eπ± = 162 MeV (1978GE11) and 291 MeV (1981GE03). Quadrupole contributions appear to be quite important for the elastic scattering at 162 MeV (1978GE11), but are much less so at higher energy (1981GE03). The inelastic scattering suggest the importance of radial localization effects (1981GE03). For a study of the (π+, π0) reaction see (1981BO06). For measurements of inclusive charged pion scattering yields see (1981MC09).
The population of 9Be*(0, 1.7, 2.4, 3.1, (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 measured at En = 5.9 to 14.2 MeV [see (1974AJ01, 1979AJ01)] and at 3.5 to 7.1 MeV (1980CO1U; n0, n2), 6.97 to 14.93 MeV (1978HO23; n0, n2) and at 14.6 MeV (1982HAZK; n0). See also (1981DAZZ, 1983ANZY), (1979BY01, 1980AK01; theor.) and 10Be.
Elastic and inelastic scattering angular distributions have been studied at many energies in the range Ep = 5 to 1000 MeV [see (1974AJ01, 1979AJ01)] and at Ep = 2.31 to 2.73 MeV (1980BO1L; p0), 35.2 MeV (1980FA07; p0), 72 MeV (1982AU1B; p0), 225 MeV (1981RO1F; p0) and 1 GeV (1979AL26; p0). The elastic distributions show pronounced diffraction maxima characteristic of the optical model. A quadrupole-deformed optical model potential is necessary to obtain a good fit to the p0 and p2 angular distributions: see (1974AJ01).
The structure corresponding to 9Be*(1.7) is asymmetric: the line shape peaks 25+15-11 keV above the threshold for 8Be + n. The population of 9Be*(1.7) has been studied for Ep = 4.2 to 5.5 MeV: it is consistent with a scattering length of about -20 fm between a neutron and 8Be. The weighted mean of the values of Ex for 9Be*(2.4) listed in (1974AJ01) is 2432 ± 3 keV. 9Be*(3.1) has Ex = 3.03 ± 0.03 MeV, Γ = 250 ± 50 keV, Jπ = 3/2+, 5/2+. Higher states are observed at Ex = 4.8 ± 0.2, 6.76 ± 0.06 [Jπ = 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]. For 9Be*(2.4, 6.8) B(E2 ↑) = 49 ± 6 and 24 ± 4 fm4 and Γ(E2 ↓) = 0.0025 and 0.10 eV, respectively. The strong population of 9Be*(2.4, 6.8) is consistent with the assumption that they have Jπ = 5/2- and 7/2-, respectively, and are members of the ground-state K = 3/2- band. See (1966LA04, 1974AJ01) for references.
The elastic scattering studied at Ep = 25 MeV (1974BI14) and 225 MeV (1981RO1F) shows that the depolarization parameter, D, deviates from unity and thus that a spin-spin term must be included in the optical parameter. The spin-flip probability at Ep-bar = 31 MeV is ≈ 0 for the p2 group, which is expected in view of the collective nature of the transition (1981CO08). See also (1978AL1G) and (1979BY01, 1980KO1V, 1981BA50, 1981CO08, 1981GU1B, 1981GU1F, 1981KR17, 1982BA1X, 1982BA14, 1982GUZS; theor.).
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 p-proton and an s-proton respectively, and a third peak of uncertain assignment (perhaps due to unresolved states) with Q = -32.3 ± 0.6 MeV. See (1974AJ01). See also (1979KO21; also for (p, pX)), (1979KRZX, 1981FR24). For reaction (b) see (1974AJ01). Reactions (c) and (f) are dominated by quasifree processes at Ep = 101.5 MeV: Sα(L = 0) = 0.45, Sα(L = 2) = 0.55 (1980NA09). See also (1982NA1N). Reaction (d) at Ep = 10 - 24 MeV involves the 5/2+ state [3.01 ± 0.02 MeV]. 9Be*(4.7) is also involved (1978JE01). See also (1982PE1F). For pion production see (1979BU1D). See also (1979BA28) and (1978WO1A, 1979BO27, 1979DO03, 1979KI10, 1979MA1M, 1980BO12, 1981IS11; theor.).
Inelastic groups have been reported to 9Be*(1.7), to states with Ex = 2431.9 ± 7.0 keV and 3040 ± 15 keV (Γ = 294 ± 20 keV), and to 9B*(4.7, 6.8): see (1974AJ01). See also (1978ZE03, 1979DO03; theor.) and 11B in (1985AJ01).
Angular distributions of elastically scattered tritons have been measured at Et = 2.10 MeV [see (1974AJ01)] and at Epol. t = 15 and 17 MeV (1978SC02). Reaction (b) at Et = 4.2 and 4.6 MeV proceeds via 9Be*(2.4): see (1974AJ01). See also (1981ME1D; theor.).
Angular distributions have been studied for E(3He) = 1.6 to 32.6 MeV and at 217 MeV [see (1974AJ01, 1979AJ01)] and at E(3He) = 46.1 MeV (1979GO07; elastic). For optical model parameters see references in (1979AJ01). At E(3He) = 39.8 MeV, 9Be*(1.7, 2.4, 3.1, 4.7, 6.8, 14.4) are populated. In a study of reaction (b) the (5He + α) system is found to be mainly in an S-state: the probability of finding such a cluster in 9Be is Neff = 0.05 (1975KA05). At E(3He) = 2.1 to 2.7 MeV quasifree processes are reported by (1978AR21): see 8Be. See also (1981DE1X) and (1979KA1G).
Angualr distributions have been studied at many energies in the range Eα = 5.0 to 104 MeV [see (1974AJ01)] and at Eα = 35.5 MeV (1982PE03; α0, α1, α2, α4, α5 and α to 9Be*(11.28)) and 65 MeV (1980HA33; α0, α2, α5). See (1972DE01) for a discussion of optical model parameters. The structure (5He + α) for 9Be is found to be much more probable than (6Li + t ): the ratio of spectroscopic factors is about 30 (1972DE01).
At Eα = 35.5 MeV, states belonging to the K = 3/2- ground-state band are strongly excited [9Be*(0, 2.43, 6.76, 11.28); it is suggested that the latter has Jπ = (9/2-); see, however, reaction 12]. The first three states belonging to the K = 1/2+ band are also excited [9Be*(1.68, 3.05, 4.70)] (1982PE03; coupled channels analysis). For reaction (b) see (1974AJ01) and (1980ZH1A; 18 MeV) and (1980WA07; 140 MeV). Sα = 0.96 (1976WO11). For reaction (c) see (1974AJ01). See also (1978ZE03, 1981BA20, 1982BU1D; theor.).
Elastic angular distributions have been measured at E(6Li) = 4, 6 and 24 MeV and at E(7Li) = 24 and 34 MeV: see (1979AJ01).
Elastic angular distributions are reported at E(10B) = 20.1 and 30 MeV (1980BO14).
Elastic angular distributions have been measured for reaction (a) at E(12C) = 12, 15, 18 and 21 MeV and E(9Be) = 14, 20, 26 and 43 MeV [see (1979AJ01)] and at E(9Be) = 14, 20 and 26 MeV (1979UN01), 20 MeV (1979BO1K), 20 and 26.1 MeV (1979JA04), 50 MeV (1977ST20), 69.7 and 76.6 MeV (1979MA21) and 158.4 MeV (1983FUZY). For yield and fusion cross-section measurements see (1978MA44, 1979MA21, 1981JA09, 1982DEZL, 1982HU06). Elastic angular distributions for reaction (b) are reported at E(9Be) = 14, 20 and 26 MeV (1979UN01) and 19.5 and 25.0 MeV (1979JA04). See also (1978TA1B, 1982JA1E) and (1978GR22, 1980BR05, 1980OH1B, 1981GR17, 1981HU07, 1982LO13, 1983DE1U; theor.).
Elastic angular distributions have been reported in the range E(16O) = 15 to 30 MeV [see (1979AJ01)] and at E(9Be) = 14, 20 and 26 MeV (1979UN01) and 158.4 MeV (1983FUZY), as well as at E(18O) = 12.1, 16 and 20 MeV [see (1974AJ01)]. See also (1981ST1P, 1982BE54), (1979HU1B, 1979MA30, 1979PAZY, 1981GR17, 1981GU1B; theor.).
Elastic angular distributions have been measured at E(9Be) = 14, 20 and 26 MeV for reactions (a), (c), (d) and at 14 and 17 MeV for reaction (d): see (1979AJ01). Recent measurements are at E(9Be) = 12 to 30 MeV (1980BO11, 1981HU08; reaction (d)), 14, 20 and 26 MeV (1978UN02, 1979UN01; reactions (a) (nat. Mg), (c), (d), (f)), 20 MeV (1978JA07; reaction (d)), 27 and 40 MeV (1981GL03; reaction (d)), 40 MeV (1981HN04; reactions (e), (f), (g)), 45 and 60 MeV (1980EC01; reactions (d), (f)), 50 MeV (1977ST20; reactions (d), (f)), 158.4 MeV (1983FUZY; reactions (b), (c)) and 121 and 201.6 MeV (1980ZI02; reaction (d)). For fusion studies see (1980EC03, 1983EC01). See also (1980EC04) and (1979SA1E, 1980HU09; theor.).
Forward angular distributions have been obtained at Ed = 15.0 MeV for the tritons to 9Be*(0, 1.7, 2.4, 3.1). The ground-state transition is well fitted by l = 1. The transition to 9Be*(1.7) [≈ 165 ± 25 keV] is consistent with Jπ = 1/2+, that to 9Be*(2.4) is quite well fitted with l = 3 [Jπ = 5/2-], and that to 9Be*(3.1) [Γ = 280 ± 25 keV] is consistent with l = 2. No other narrow states are seen up to Ex = 5.5 MeV (1970AU02).
The summed proton spectrum at Ep = 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): see (1974AJ01).
Angular distributions of the 3He groups corresponding to 9Be*(0, 2.4) have been studied at Ed = 11.8, 28 and 52 MeV [the latter also to 9Be*(6.7)], and at Ed = 15 MeV: S = 0.72 and 0.82 for 9Be*(0, 2.4). At Ed-bar = 52 MeV 9Be*(11.3) appears to be strongly populated: see (1979AJ01).
At Et = 12.9 MeV α-groups are observed to the ground state of 9Be and to excited states at Ex = 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 9Be*(14.39) is very weakly populated [≈ 5% of intensity of α2]. The angular distribution of the α2 group shows sharp forward and backward peaking. The α0 group is not peaked in the backward direction: see (1979AJ01). Angular distributions are also reported at Et = 0.9 and 1.1 MeV to 9Be*(2.4) (1980CI1B). A study at Et = 1.0 to 3.2 MeV finds Ex = 1.750 ± 0.025 MeV, Γ = 220 ± 8 keV: see (1974AJ01). See also (1978KR16; theor.) and 13C in (1981AJ01).
The angular distribution of t0 has been measured at En = 14.4 MeV: see (1974AJ01).
At Ep = 45 MeV angular distributions are reported for the 3He ions corresponding to 9Be*(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 9Be*(15.13). It is suggested that 9Be*(11.8, 13.8, 15.96) are the J = 3/2-, T = 1/2 analogs to 9B*(12.06, 14.01, 16.02). Angular distributions are also reported at Ep = 40 MeV. The intensity of the group to 9Be*(3.1) is ≈ 1% of the ground-state group at that energy: see (1974AJ01). The excitation energy of the first T = 3/2 state is Ex = 14392.9 ± 1.8 keV (1974KA15), using Qm. See also (1981CO2D) and 12C in (1985AJ01).
Alpha groups reported corresponding to 9Be*(0, 1.7, 2.4, 3.1). The width of 9Be*(1.7) [Ex = 1.70 ± 0.01 MeV] is Γc.m. = 220 ± 20 keV. The weighted mean of the values of Ex of 9Be*(2.4), reported in (1974AJ01), is 2425 ± 3 keV. The 5/2+ state is at Ex = 3.035 ± 0.025 MeV: Γc.m. = 257 ± 25 keV. The ratio Γγ/Γ of 9Be*(1.7) ≤ 2.4 × 10-5, that for 9Be*(2.4) is reported to be (1.16 ± 0.14) × 10-4. Since Γγ is known from (e, e') [see Table 9.8 (in PDF or PS): 0.089 ± 0.010 eV], Γ = 0.77 ± 0.15 keV. See (1974AJ01, 1979AJ01) for references.
Angular distributions for α0 and α2 are reported at Ed = 0.39 to 3.9 MeV and at 12 MeV [see (1974AJ01, 1979AJ01)]. Reaction (b), at Ed = 10.4 and 12.0 MeV, proceeds via 9Be*(2.4) and to some extent via 9Be*(3.1, 4.7) and possibly some higher excited states. The dominant decay of 9Be*(2.4) is to 5He(0) + α while 9Be*(3.1, 4.7) decay to 8Be(0) + n. It should be noted, however, that the peaks corresponding to 9Be*(3.1) have a FWHM of ≈ 1 MeV, which may imply that 9Be*(2.8) is involved.
Angular distributions of the α0 group have been measured at En = 13.9 to 18.8 MeV [see (1974AJ01)] and at 14 MeV (1981HAZW). 9Be*(1.7, 2.4, 3.1) are also populated. At En = 14.7 MeV (1981GU12) report the involvement of 9Be*(6.76) which subsequently decays by n-emission. Reaction (b) at En = 13 to 18 MeV populates 9Be*(2.4). See also (1979SUZW), 12C in (1980AJ01) and reactions 30 and 34 in 13C in (1981AJ01).
Angular distributions have been obtained at E(3He) = 70 MeV for the transitions to 9Be*(0, 2.4) and 7Be*(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).
See (1981RU09; Ed = 13.6 MeV).