(See Energy Level Diagrams for 9Be)
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 9Be is 0.42 ± 0.04 (1977LA11).
The 0° differential cross section for reaction (a) increases monotonically between Et = 0.10 and 2.4 MeV (1960SE12, 1961VA43, 1962SE1A) except for a resonance at Et = 1.875 MeV (9Be* = 18.938). The excitation function for 8Li (reaction (b)) increases monotonically for Et = 0.275 to 1.000 MeV (1972CI05, 1972CI1C). 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] (1973AB10). For reaction (c), (d) and (e) see (1966LA04). See also 8Li and (1977SU1A).
Angular distributions of p0 have been measured at Eα = 10.2 to 14.7 MeV and at 30 MeV: see (1974AJ01). In a study of the inverse reaction [9Be(p, α)6Li] at 45 MeV, the spectroscopic factors for (6Li + t) and (5He + α) cluster structures in 9Be are calculated to be 0.003 and 0.102, respectively (1972DE01, 1972DE02).
For Ed = 0.1 to 1.1 MeV, a resonance in the yield of capture γ-rays is observed at Ed = 362 ± 3 keV (1965WO01), 361 ± 2 keV (1965IM01), corresponding to 9Be*(16.976) 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 (1965WO01). The angular distribution of the γ-rays to 9Be(0) is isotropic to within 7% (1965IM01). The branching ratios to 9Be*(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 Ex and Γ of 9Be*(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 [9Be*(16.98)] and is consistent with Jπ = (1/2)- for 9Be*(2.8) (1971SC19).
The yield of neutrons has been measured for Ed = 0.2 to 19 MeV [see (1974AJ01)] and for 0.4 to 3.0 MeV (1975MC02; σt), 2.5 MeV (1974JO1C) and 14.8, 18 and 23 MeV (1977LO10). Resonances in the yield of neutrons are reported at Ed = 0.36, 0.68, 0.98 and (1.8) MeV: see Table 9.3 (in PDF or PS). Polarization measurements have been reported at Ed = 0.64 MeV and at 2.5 to 3.7 MeV: see (1974AJ01). See also (1975SE07, 1977SE09).
The yield of α-particles has been studied for Ed = 0.2 to 3.0 MeV [see (1974AJ01)] and at Ed = 0.60 to 1.25 MeV (1973RO42: α1). Resonances are observed at Ed = 0.75, 1.00 and 2.5 MeV: see Table 9.3 (in PDF or PS).
At Ed = 1.0 MeV reaction (c) is dominated by sequential decay via 8Be*(2.9) and 5Heg.s.. There is evidence also for the involvement of 9Be*(17.50): J = 3/2 is suggested (1973HE26). See also (1975DA15, 1978SP03). See also 5He, 8Be, (1975FO19; astrophysics) and (1974JO1C, 1975GO38, 1977GR1F, 1977LO10, 1977SA28; applications).
The yield of p0 has been measured for Ed = 0.29 to 0.78 MeV and the 8Li yield for Ed = 0.4 to 7.0 MeV [see (1974AJ01)] and from threshold to 3.6 MeV (1974MCZS, 1975MC02: σt; also cross sections for p0 and p1, from 0.5 MeV). The yield of 8Li has also been measured for Ed = 0.61 to 1.95 MeV (1976SC14): resonances are displayed in Table 9.3 (in PDF or PS). The total cross section at the Ed = 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 7Be(p, γ)8B data and to calculations of the S-factor, of interest in relation to the solar neutrino problem. See also (1976HA1J).
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 (1974LO10) and Ed = 10.0 to 12.0 MeV (1971BI11). See also 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 (1955MA20). The t0 yield curve (θlab = 155°) decreases monotonically for Ed = 10.0 to 12.0 MeV (1971ZA07). 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 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(3He) = 0.9 to 10 MeV [see (1974AJ01)], at 1.0 to 2.5 MeV (1975BO55: p0, p2) and at 14 MeV (1976IR02: p0). See also 10B and (1973WE15, 1975ST16; theor.).
At Eα = 30 MeV d0, d1 and d2 angular distributions have been measured (1972ME07). See also (1976LE1K).
Angular distributions of the α0 group have been measured at E(7Li) = 3.78 to 5.95 MeV (1967KI03). See also (1974AJ01).
Not reported: see (1970LK1A; theor.).
9Li decays by β- emission with τ1/2 = 178.3 ± 0.4 msec to 9Be*(0, 2.43, 2.78): see reaction 1 in 9Li, and Table 9.7 (in PDF or PS). 9Be(2.43, 2.78) are neutron unstable. The probability that 9Li decays to these two states is 0.35. The branching ratio for the 9Be*(2.43) → 8Be(0) + n decay is (6.4 ± 1.2)%. 9Be*(2.78) decays mainly to 8Be(0) + n. The assignment Jπ = 1/2- to 9Be*(2.78) derives from the nature of the 9Li decay, and the large value of θ2p [0.48 ± 0.06] which is in agreement with the shell model prediction that the 1/2- state should decay mainly by p-wave neutron emission to 8Be(0): if Jπ = 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 σmax = 1.6 mb. The cross section then decreases slowly to 1.2 mb at Eγ = 40 keV (1967BE49). From bremsstrahlung studies, peaks in the (γ, Tn) cross section are observed corresponding to Ex = 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 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). See also (1976BE1H).
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 (1977BU02) 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 (1978BU01).
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 (1974AH03, 1975AH06). (1969DO09) report an integrated cross section of 156 ± 15 MeV · mb for Eγ = 10 to 29 MeV and resonant structure at Eγ = 11.8, (13.5), 14.8, (17.3), (19.5), 21.0, (23.0) and (25.0) MeV (1969DO09). Fine structure is reported at Eγ = 20.47 ± 0.04 and 20.73 ± 0.04 MeV (1964TE04). The absorption coefficient of 6.418 MeV γ-rays is reported by (1975MO27). Double pair production by 6.6 MeV γ-rays has been observed by (1976RO1N): σππ/σπ = (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 9Be levels at 17 - 19 MeV (1962CL06) followed by the giant resonance at Eγ ≈ 23 MeV (1962CL06; σ = 2.64 ± 0.30 mb). (1966DE13) report structure attributed to eleven states of 9Be with 18.2 < Ex < 32.2 MeV. 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) (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 (Eγ = 21 → 33 MeV) for reaction (a) to 7Li*(0 + 0.4) and 0.6 ± 0.3 MeV · mb (Eγ = 25 → 33 MeV) for reaction (b) 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).
See (1977CR1C) and (1974AJ01).
< r2 >1/2 = 2.46 ± 0.11 fm, Q = 6.5-0.6+0.9 fm2, b = 1.5-0.2+0.3 fm [b = oscillator parameter] (1973BE19);
< r2 >1/2 = 2.519 ± 0.012 fm, Q = 6.4 ± 2.4 fm2 (1972JA10) and private communication to J.C. Bergstrom);
< 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] (1975LA23; see also for calculations of (b)).
The elastic scattering of electrons has been studied for Ee 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 Ee = 1.0 and 2.0 MeV by (1968RE11). For reaction (b) see (1974AJ01). At Ee = 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: Ee = 500 MeV; observe a peak at Ex ≈ 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 9Be*(0, 1.7, 2.4, 3.1) and possibly 9Be*(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 En = 14 MeV [see (1974AJ01)], at 5.9, 10.1 and 14.2 MeV (1977DR09: n0, n1+2+3+4), and 14.1 MeV (1974HY01: n0, n2). See also (1974HO1E, 1975HO1F, 1976BI1B). For reactions (a) and (b) see also 10Be. 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 Ep = 5 to 1000 MeV [see (1974AJ01)] and (1974YA1C: p0(5.0, 6.0 MeV), p1(5.2, 6.0 MeV), p2(4.2 → 6.0 MeV)), (1977CO1G: p0(35.2 MeV)) and (1976AL1G: p0; 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 quadrupole-deformed optical model potential with a deformation parameter β = 1.1 provides an improved description of the elastic data and a good fit to the p2 data.
The structure corresponding to 9Be*(1.7) is asymmetric: the line shape peaks 25+15-11 keV above the threshold for 8Be + n (1970TU06). 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. An anomaly at Ep = 5.1 MeV is attributed to FSI between n, p and 8Be (1974YA05).
The weighted mean of the values of Ex listed in (1974AJ01) is 2432 ± 3 keV. 9Be*(3.1) has a width 250 ± 50 keV (1960SP08), Jπ = 3/2+, 5/2+, Ex = 3.03 ± 0.03 MeV (1956BO18), 3.04 ± 0.05 MeV (1960SP08). 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] (1965HA17). (1965JA1A) reports 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 also (1966LA04).
(1974BI14) have studied the elastic scattering at Ep = 25 MeV: a non-zero D (depolarization) is reported; its existence constitutes evidence of a nucleon-nucleus spin-spin interaction. On the other hand (1976MOZF: Ep-bar = 32 MeV) find no evidence for a non-zero value of D in the transition to 9Be*(2.4). See also (1977KI04, 1978FR1D), (1974LO1B), (1973WE15, 1974GU13, 1974GU1D, 1974JA1F, 1978BY1B, 1978BY1C, 1978WO13; theor.) and 10B.
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 (1966TY01: Ep = 460 MeV). See also 8Li and (1973MA67; theor.). For reaction (b) see (1974AJ01). Quasi-free scattering of the incident protons by zero-momentum α-particle clusters is consistent with the data obtained at Ep = 26.0, 35.0, 46.8 and 57 MeV (1968RO19, 1972QU01). At Ep = 100 MeV (1977CO07, 1977RO02) find < Sα > = 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 Ep = 12.7 MeV, 9Be*(3.05) is strongly populated and 9Be*(4.70) is also observed in reaction (d) (1977JE01). See also Table 9.5 (in PDF or PS). (1978CH07), 8Be (1977WA05; Ep = 45 and 47 MeV), (1974MI05, 1974YA05) and (1974AV02; theor.). See also (1974AJ01). In reaction (f), at Ep = 100 MeV, (1977CO07) find < Sα > = 0.47 ± 0.04.
Elastic angular distributions have been studied in the range 1.1 to 410 MeV [see (1974AJ01)] and at Ed = 1.0 to 2.2 MeV (1972LO05), Ed-bar = 15 MeV (1976DA15; also d2, d4) and Ed = 27.98 MeV (1977OO01). Angular distributions to 9Be*(2.4) have also been reported at Ed = 11.8, 14.35 and 15.8 MeV: see (1974AJ01).
Inelastic groups have been reported to 9Be*(1.7, 2.4, 3.1, 4.7, 6.8): see (1966LA04). (1968KR02) report Ex = 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 Et = 2.10 MeV (1969HE08, 1970CO04). Reaction (b) at Et = 4.2 and 4.6 MeV proceeds via 9Be*(2.4) (1967SE11).
Angular distributions of elastically scattered 3He particles have been obtained at E(3He) = 4 to 32.3 MeV [see (1974AJ01)], at E(3He) = 1.6 to 2.4 MeV (1974BO38) and 32.6 MeV (1975BU11; polarized 3He). See also (1975DA1A). At E(3He) = 217 MeV (1973WI07, 1976WI05) angular distributions have been studied to 9Be*(0, 2.4). For optical model parameters see discussions in (1972BU30, 1973WI07, 1976WI05). At E(3He) = 39.8 MeV inelastic 3He groups are observed to 9Be*(1.7, 2.4, 3.1, 4.7, 6.8, 14.4) (1969BA06). See also (1976RO1L). 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). See also 8Be.
Elastic scattering has been studied at many energies for Eα = 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 (5He + α) for 9Be is found to be much more probable than (6Li + t): the ratio of spectroscopic factors is about 30 (1972DE01, 1972DE02) .
Inelastic groups have been observed to 9Be*(1.7, 2.4, 3.1, 6.8, 11.3): see (1966LA04). The angular distribution of the α1 group to 9Be*(1.7) is consistent with Jπ = 1/2+ (1964LU02: Eα = 18.4 MeV). The angular distributions for α2 are consistent with l = 2 [Jπ = (1/2, 5/2, 7/2)-] (1958SU14, 1967FU08). Analysis based on the rotational model leads to a deformation coefficient β2 = 0.34 ± 0.01 (1964GR39).
The summed α-spectra from reaction (b) show a peak corresponding to quasi-elastic scattering leaving 5He in its ground state. The angular distribution peaks at the angle corresponding to zero-momentum α-cluster. The probability of formation of such clusters is (7+13-5)% (1969PI11). See also (1977WA1M). (1976WO11) find Sα = 0.96.
A study of continuum neutrons at Eα = 4.9 to 6.4 MeV (reaction (c)) indicates that sequential decay takes place via 9Be*(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(6Li) = 4 and 6 MeV (1974VO06) and 24 MeV (1968DA20) and at E(7Li) = 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(12C) = 12, 15, 18 and 21 MeV (1970BA49) and E(9Be) = 14, 20 and 26 MeV (1978LA1G) and 43 MeV (1977MA1L). The neutron spectroscopic factor for 9Be 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(14N) = 25 (1966OE1A) and 27.3 MeV (1959HA28).
Elastic angular distributions have been reported at E(16O) = 15, 18, 21.5 and 25 MeV (1970BA49), 25.7 to 29.5 MeV (1975FU05) and 30 MeV (1969KR03), and at E(18O) = 12.1, 16 and 20 MeV (1971KN05). See also (1974TA1C, 1978CH02), (1978EN06) and (1978PA1B; theor.).
Elastic angular distributions have been measured at E(9Be) = 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 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) [Γ ≈ 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).
See reactions 24 and 26 in10B.
A good fit to the angular distributions of the deuterons to 9Be*(0, 2.4) has been obtained at En = 14.4 MeV, using DWBA. The spectroscopic factors are in close agreement with shell model predictions (1965VA05). See also 11B in (1980AJ01).
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) (1966TY01). See also 10B.
Angular distributions of the 3He groups corresponding to 9Be*(0, 2.4) have previously been measured at Ed = 11.8 and 28 MeV: see (1974AJ01). Recent angular distribution measurements at Ed-bar = 15 MeV (1974LU06; to 9Be*(0, 2.4)) and at Ed = 52 MeV (1975SC41; to 9Be*(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 9Be*(11.3) appears also to be strongly populated. The data for 9Be*(0, 2.4) are very similar, as predicted, to those obtained in the mirror reaction: see reaction 12 in 9B. See also (1974DA1D; theor.) and 12C in (1980AJ01).
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 (1968AJ01). A study at Et = 1.0 to 3.2 MeV finds Ex = 1.750 ± 0.025 MeV, Γ = 220 ± 8 keV. The angular distribution of the corresponding α-group has been determined at Et = 2.5 MeV (1971GE09). See also (1977CI1A) and 13C in (1981AJ01).
The ground state angular distribution has been measured at E(14N) = 27.5 MeV (1962NE01).
The angular distribution of t0 has been measured at En = 14.4 MeV (1970MI14).
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 Jπ = 3/2-, T = 1/2 analogs to 9B*(12.06, 14.01, 16.02) (1971HA10). Angular distributions are also reported at Ep = 40 MeV (1971KA21: α0, α2). The intensity of the group to 9Be*(3.1) is ≈ 1% of the ground state group (1971KA21). The excitation energy of the first T = 3/2 state is Ex = 14392.6 ± 1.8 keV (1974KA15) using the (1977WA08) mass for 9Beg.s.. For reaction (b) see (1964BA1C).
Alpha groups are reported corresponding to 9Be*(0, 1.7, 2.4, 3.1). The width of 9Be*(1.7) [Ex = 1.70 ± 0.01 MeV (1975FO13)] is Γc.m. = 224 ± 25 (1958KA31, 1966PU02), 200 ± 10 keV (1975FO13). 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 = 3.02 ± 0.03 MeV (1955LE36), 3.05 ± 0.03 MeV (1956BO18): Γc.m. = 257 ± 25 keV (1958KA31, 1966PU02). The ratio Γγ/Γ of 9Be*(1.7) ≤ 2.4 × 10-5, that for 9Be*(2.4) is (1.16 ± 0.14) × 10-4 (1966PU02). 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.
Angular distributions for α0 and α2 are reported at Ed = 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 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 (1971RE19). 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 (1971RE19). See also (1978GR07) and 13C in (1981AJ01).
Angular distributions of the α0 group have been measured at En = 13.9 to 18.8 MeV; 9Be*(1.7, 2.4, 3.1) are also populated: see (1974AJ01). Reaction (b) at En = 13 to 18 MeV involves 9Be*(2.4) (1966MO05). See also (1975AN01, 1976AN16), (1973PE19; theor.) and 12C in (1980AJ01), and 13C in (1981AJ01).
Angular distributions have been obtained for the transition to 7Be*(0, 0.43) + 9Beg.s. (1972RU03: 42 MeV).
See (1975RA13; theor.).
See 13C in (1981AJ01).
See (1975OB01) and 14N 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).
At Eα = 65 MeV angular distributions have been measured for the transitions to 9Be*(0, 2.4) (1976WO11).
See (1974CH1Q) and (1978EN06).
See (1974BA15) and (1978EN06).