
^{9}Be (1974AJ01)(See Energy Level Diagrams for ^{9}Be) GENERAL: See also (1966LA04) and Table 9.2 [Table of Energy Levels] (in PDF or PS). Shell model: (1961KO1A, 1965CO25, 1965GR18, 1965VO1A, 1966AD06, 1966BA26, 1966HA18, 1966MA1P, 1966WI1E, 1967CO32, 1967ST1C, 1968GO01, 1969BO1V, 1969BO19, 1969BO33, 1969GU03, 1969VA1C, 1970CO1H, 1971CO28, 1971GR02, 1971NO02, 1972LE1L, 1973HA49, 1973KU03). Aplha and cluster models: (1965NE1B, 1966HI1A, 1967TA1C, 1968KU1B, 1969BA1J, 1969NE1C, 1970BA1Q, 1971LE1N, 1971NO02, 1972AB19, 1972CH1N, 1972HI16, 1972IK1A, 1972LE1L, 1973KU03, 1973OK1B). Collective and deformed models: (1965VO1A, 1966EL08, 1967BO1K, 1967BO34, 1973KU13, 1973SL02). Special levels: (1966AD06, 1966BA26, 1966EL08, 1967CO32, 1967ST1C, 1968BO19, 1968GO01, 1969BO1V, 1969BO33, 1969GU03, 1969HA1G, 1970PE18, 1970TO1E, 1971CO28, 1971GR02, 1971LI30, 1971NO02, 1972BE1E, 1972CH1N). Electromagnetic transitions: (1965CO25, 1966BA26, 1966EL08, 1967KU1E, 1968KU1D, 1969HA1G, 1969VA1C, 1971GR02, 1972AB19, 1972NA05, 1973HA49, 1973SL02). Astrophysical questions: (1968HA1C, 1970BA1M, 1972CL1A, 1972KO1E, 1973AU1H, 1973LA19, 1973RA37, 1973RE1G, 1974AU1A). Special reactions: (1968HA1C, 1968YI01, 1969AR13, 1969GA18, 1969YI1A, 1971AR02, 1972VO06, 1973KO1D, 1973KU03, 1973LA19, 1973WI15). Muon capture: (1968BA2G, 1969WU1A, 1970FA15, 1971DE2D, 1972BU29, 1973MU11). Pion capture and reactions: (1967ME1F, 1967MI1B, 1968BA2G, 1968ER1A, 1968NO1A, 1968WI1B, 1969BU1C, 1969CA1B, 1969CH1C, 1969KO1F, 1969MO1E, 1970BA1E, 1970BE1J, 1970CA1L, 1970ER1A, 1970GO28, 1971CA01, 1971CA1J, 1971FA09, 1971GO14, 1971MA1C, 1971RE1H, 1971SE02, 1972AB1H, 1972BE34, 1972BU1P, 1972HU1A, 1972MA1H, 1972SA10, 1972SE1F, 1973BA2R, 1973BA2V, 1973DI1H, 1973GA20, 1973HS1A, 1973HS1B, 1973JA1K, 1973NY04, 1973OS01, 1973PE1E, 1973SQ01, 1973UL1D). Kaon reactions: (1973BA1Y). Other topics: (1965CO25, 1965VO1A, 1966CH1B, 1966DO1C, 1966HA18, 1966HE1C, 1966WI1E, 1967BA12, 1967CA17, 1967CH1H, 1967MO1H, 1968KO1H, 1968GO01, 1969GU03, 1969LE1G, 1970CO1H, 1970GR33, 1970KA1K, 1970PA1D, 1970PE18, 1970SA05, 1971DA13, 1971ER1C, 1972AN05, 1972CA37, 1972CH1P, 1972FR09, 1972HA57, 1972LE1L, 1972PN1A, 1972RA1J, 1972TA31, 1972TU1B, 1973BA1Y, 1973BE1N, 1973CL09, 1973JU2A, 1973KO1J, 1973KU03, 1973MA48, 1973RA1E). Ground state properties: (1965CO25, 1965GR18, 1965VO1A, 1966AD06, 1966BA26, 1966EL08, 1966MA1P, 1966WI1E, 1967SH05, 1967SH14, 1968DZ1A, 1969AF1A, 1969BO19, 1969GU03, 1969HE1N, 1969JA1M, 1969PE1D, 1969VA1C, 1971AU1G, 1972FR09, 1972LE1L, 1973MA1K).
Q = 0.065^{+0.009}_{0.006} b (1973BE19). See also (1967BL09, 1969FU11, 1971SH26).
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). 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 reactions (c) and (d) see (1966LA04). For reaction (e) see (1966LA02, 1967BE13). See also ^{5}He, ^{7}Li and ^{8}Li.
Angular distributions of ground state protons have bee measured at E_{α} = 10.2, 11.5 and 13.5 MeV (1960MA15), 13.6 and 14.7 MeV (1962KO13) and 30 MeV (1960KL03). See also (1966LA04).
See (1964KI02).
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*(16.977) with Γ_{cm} < 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 100/8.5 ± 4.3/10.6 ± 5.3/  / ≤ 4.5/9.6 ± 4.8 (1965IM01), 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). See also (1968SN1A).
The yield of neutrons has been measured for E_{d} = 0.2 to 4.8 MeV (1952BA1A, 1957SL01, 1965IM01), 0.86 to 1.33 MeV by (1969NU1C), 3 to 8 MeV by (1967KE1F: yield of neutrons to ^{8}Be*(16.6, 17.6, 18.1), at one MeV intervals) and 5 to 19 MeV by (1973WE19). Polarization measurements have been reported by (1971MO1R, 1973MO07: E_{d} = 0.64 MeV; n_{0}) and (1970TH08: E_{d} = 2.5 to 3.7; n_{0}, n_{1}). See also (1972SE09; theor.) and (1966LA04). Resonances in the yield of neutrons are observed at E_{d} = 0.36, 0.68, 0.98 and (1.8) MeV: see Table 9.3 (in PDF or PS). The yield of αparticles has been measured for E_{d} = 0.2 to 0.3 MeV by (1964MA1F), 0.6 to 2.0 MeV by (1971FR04), 0.7 to 1.6 MeV (1969DE31) and 0.7 to 3.0 MeV by (1963PA04). The excitation function for reaction (b) shows resonances at E_{d} = 0.75 and 1.00 MeV (1971FR04), 0.78 and 1.08 MeV (1969DE31), as well as a broad structure at E_{d} = 2.5 MeV (1963PA04). Also reported are αparticles from reaction (a) associated with ^{8}Be*(11.4, 16.6, 16.9); the αparticles from the decay of ^{8}Be*(11.4) seems to show resonance behavior at E_{d} = 0.7, 1.0 and 1.75 MeV. It is not clear whether the αparticles corresponding to ^{8}Be*(16.6) show resonance at E_{d} = 2.5 MeV or whether the ^{8}Be*(16.9) αparticles are appearing at this point (1963PA04). A study of the B_{L} coefficients of the angular distributions of the α_{0} group for E_{d} = 0.45 to 2.0 MeV and of the αα angular correlation coefficient, together with a reanalysis of the (d, d_{0}) data of (1964FO1B), lead to assignments of 3/2^{} and (3/2, 5/2)^{+} for ^{9}Be*(17.30, 17.50). The analysis also requires a (3/2, 5/2)^{} state at lower excitation energy and a (3/2, 5/2)^{+} state at higher energy (1972DE44). See also (1973MO07) for an interpretation of results from reaction (a). A kinematically complete study of reaction (c) at E_{d} = 1.0 MeV shows that the yield 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) [measurement of relative yield for E_{d} = 0.9 to 1.1 MeV]: J = 3/2 is suggested (1973HE26). See also ^{5}He, ^{8}Be and (1966AS04, 1967KE1F, 1967VA11, 1968WI1E, 1973HE06). See also (1966NU1B, 1966PO1D, 1967BE13, 1967WI1C, 1968DA1H, 1971DA21, 1972BR1R, 1972SU1E, 1973DA1R).
The yield of p_{0} measured for E_{d} = 0.29 to 0.78 MeV shows a single resonance with E_{d} = 360 ± 3 keV, Γ < 2 keV, Γ_{p}/Γ_{γ} ≈ 0.5 (1965IM01, 1965WO01): see also reaction 4. The yield of ^{8}Li has been measured for E_{d} = 0.4 to 4 MeV (1952BA1A, 1954BA46, 1956BE1A, 1960KA05), for E_{d} = 0.62 to 1.97 MeV by (1972SC1U) and for E_{d} = 2.0 to 7.0 MeV by (1973AB10): observed resonances are displayed in Table 9.3 (in PDF or PS). The yield of 0.98MeV γrays [from ^{7}Li(d, p)^{8}Li*] rises monotonically from E_{d} = 1.9 to 3.3 MeV (1962CH14). The total cross section at the E_{d} = 0.77 MeV resonance is 202 ± 9 mb (1972SC1U). Earlier values were 176 ± 15 mb (1960KA05) and 211 ± 15 mb (1966PA16). We adopt 205 ± 8 mb. This cross section is important since the ^{7}Be(p, γ)^{8}B data are normalized to it and the Sfactor is of interest in relation to the solar neutrino problem: see (1968PA1M). See also ^{8}Li.
The upper limit for the relative partial width for elastic scattering at E_{d} = 0.36 MeV (^{9}Be* = 16.98), Γ_{d0}/Γ_{γ} is 400 (1965IM01). The elastic scattering, at 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)] (1964FO1B) [and discussion in (1972DE44) and in reaction 5]. The elastic scattering cross section (θ_{cm} = 162°) decreases monotonically for E_{d} = 10.0 to 12.0 MeV (1971BI11). See also ^{7}Li.
The cross section for reaction (a) rises 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.
See (1959AJ1C, 1962SE1A) and ^{10}Be.
Observed proton groups are listed in Table 9.4 (in PDF or PS) (1968CO07). See also Table 9.5 (in PDF or PS) in (1966LA04) for a listing of the older work. Angular distributions have been measured for the protons to ^{9}Be*(0, 1.7, 2.4, 3.1) at E(^{3}He) = 0.90 to 1.10 MeV (1971ST35: not to ^{9}Be*(1.7)), 2.2 to 3.2 MeV (1969SA04, 1972LI31) and at E(^{3}He) = 10 MeV (1970DI12, 1970DI1F), and for the group corresponding to ^{9}Be*(14.39) at E(^{3}He) = 10 MeV (1971AD01). The characteristics of the neutron and γdecays of ^{9}Be states are displayed in Tables 9.5 (in PDF or PS) and 9.6 (in PDF or PS) (1965GR08, 1965LY01, 1966CH20, 1968CO08, 1968KR02, 1971AD01, 1972AD04, 1972MC1E). See also (1964MA57, 1970LI1Q), (1969BA1Z), (1968SA1G, 1968TA1N, 1970LK1A, 1971WE1L; theor.), ^{8}Be and ^{10}B.
At E_{α} = 30 MeV angular distributions have been measured for the deuterons corresponding to ^{9}Be*(0, 1.7, 2.4) (1972ME07). See also (1971BU1K; theor.) and (1966LA04).
At E(^{7}Li) = 2.9 MeV αparticle groups are observed corresponding to ^{9}Be*(0, 1.7, 2.4, 3.1, 11.9 ± 0.2 [Γ = 0.5 ± 0.1 MeV]) (1964ME07). Angular distributions of the α_{0} group have been measured at E(^{7}Li) = 3.78 to 5.95 MeV (1967KI03). At E(^{6}Li) = 26.0 MeV and E(^{7}Li) = 30.3 MeV the excitation of ^{9}Be*(0, 11.8, 13.8, 15.2, 17.8, 21.0) is reported (1971GL07). See also (1967CH34, 1968DA20, 1970OG1A) and (1966RO1E, 1966RO1F, 1966RO1H, 1969RO1G; theor.).
See (1970LK1A; theor.).
^{9}Li decays by β^{} emission with τ_{1/2} = 176 ± 2 msec to ^{9}Be*(0, 2.43, 2.78): see ^{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 allowed nature of the ^{9}Li decay, and the large value of θ^{2}_{p} [0.48 ± 0.06] which is in agreement with the shellmodel 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, 1970CH1T). See also (1963AL18, 1965SC17, 1973RO2F) and (1969MA11) for a general discussion of the problems in identifying the parameters of the lowlying states of ^{9}Be.
The photoneutron cross section has been measured from threshold to 320 MeV: see Table 9.6 (in PDF or PS) in (1966LA04). 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). A satisfactory fit to the cross section is obtained with a onelevel approximation of Rmatrix theory (1968BA1C). Peaks in the cross section of (γ, xn) are reported corresponding to E_{x} = 2.43 ± 0.03, 3.00 ± 0.03, 19.00 ± 0.03, 21.50 ± 0.05 and 23.9 ± 0.1 MeV, and there is some indication also of structure at E_{x} = 9.1, 10.8, 12.8 and 14.8 MeV (1973HU1G). See also (1966CO16, 1972TH12) and (1966LA04) for references to earlier work. The total absorption cross section has been measured for E_{γ} = 10 to 155 MeV by (1972AH1B, 1973AH1A)^{†}. The integrated cross section for E_{γ} = 16 to 29 MeV is 53 MeV · mb (1972AH1B). (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). See also (1965WY1A).
^{†} We are deeply indebted to E.G. Fuller for his very helpful remarks on the ^{9}Be + γ processes. See (1966LA04) for a discussion of the early evidence on ^{9}Be levels from reaction (a). See also (1966TH03, 1967GL1B, 1968AD09, 1968KA1D, 1971KA70, 1972BU1R, 1972CR1E), (1967SH1E) and (1965BO1B, 1965MA1H, 1967BO1K, 1967BO34, 1969BO1U, 1968MA1Y, 1968MA1X, 1968PA1H, 1969AU05, 1970SA17, 1972TA31, 1973SL02; theor.).
The yield shows structure in the energy region corresponding to the ^{9}Be levels at 17  19 MeV (1962CL06) followed by the giant resonances 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 (1966LA04) and (1966VO06, 1968AD09). See also (1965KO1B, 1969AN1H, 1971AN04, 1973DO13), (1967SH1E, 1973CO1N) and )1968MA1X; 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 (1966LA04) and (1966VO06, 1968AD09, 1969AN1H, 1971AN04, 1972AN1L) for reaction (a) and (1966VO06, 1972AN09) for reaction (b). See also (1968MA1X; theor.).
See (1967LO1B, 1968SN1A, 1969MO1H).
< r^{2} >^{1/2} = 2.46 ± 0.11 fm, Q = 6.5^{+0.9}_{0.6} fm^{2}, b = 1.5^{+0.3}_{0.2} fm [b = oscillator parameter] (1973BE19); < r^{2} >^{1/2} = 2.519 ± 0.012 fm, Q = 6.4 ± 2.4 fm^{2} ((1972JA10) and K. de Jager, private communication to J.C. Bergstrom); < r^{2} >^{1/2} = 2.43 ± 0.08 fm, Q = 3 fm^{2} (1969BE21). See also (1966AF1A, 1967BE26, 1967BE1P, 1973SL02). (1973LA1T) report b = 1.80 ± 0.03 fm from magnetic scattering. The elastic scattering of electrons has been studied at E_{e} up to 700 MeV: see (1966LA04), the references listed above, and (1965VA1G, 1966RA29, 1969BE50). Magnetic elastic scattering at θ = 180° gives indication of both M1 and M3 contributions [(1965GR18, 1966RA29): see (1968KU1D)]. Inelastic scattering reveals a number of levels: Table 9.8 (in PDF or PS) displays the parameters of these states (1960BA47, 1962ED02, 1963NG01, 1965NG1A, 1966CL01, 1967AR1A, 1968CL08, 1968VA05, 1973BE19, 1973SL02). See also (1966LA04) for a discussion of the earlier work. Electron bremsstrahlung has been measured at E_{e} = 1.0 and 2.0 MeV by (1968RE11). See also (1966PE1E), (1968GO1J) and (1965GR1E, 1965NE1B, 1966DE1K, 1966KU1C, 1967KA1A, 1967ST1G, 1967WA1E, 1967WA1F, 1968JA1D, 1968KU1B, 1969BO1V, 1969BO19, 1969VI02, 1970BE1G, 1970TI1C, 1971GO14, 1972BL12, 1972BO01, 1972DR1B, 1973OK1B; theor.). For reaction (b) see (1970AL1M; theor.). For reaction (c) see (1968AM1A, 1968BO46, 1970HI1F, 1970RE1E) and (1965AL1F, 1973HI03; theor.). For reaction (d) see (1973JU1E).
The neutron spectrum at E_{n} = 3.7 MeV is consistent with the excitation of ^{9}Be*(0, 1.7, 2.4, 3.1) with subsequent neutron decay of the two higher states (1957HU14, 1958WA05). About 1/2 of the inelastic processes involve ^{9}Be*(2.4) for E_{n} = 2.6 to 6.0 MeV; that level decays only (12 ± 5)% via ^{8}Be(0) + n (1959MA34). See Table 9.5 (in PDF or PS). At E_{n} = 14 MeV ^{9}Be*(6.8) appears to be excited (1963JE05). Angular distributions have been measured at E_{n} = 14 MeV (1958AN32, 1958NA09, 1968RO1H, 1969RO1F; n_{0}, n_{2}). See also ^{10}Be, (1966LA04) and (1965BO19, 1965FR1B, 1965GO1E, 1966AM1A, 1966BO1C, 1966BO1F, 1967BO1F, 1970DR1B) and (1969WA11; theor.).
The elastic scattering has been studied at many energies for E_{p} = 5 to 725 MeV: see (1966LA04). More recent angular distribution measurements have been carried out at E_{p} = 2.009 to 2.099 MeV (1971SI1K; p_{0}), 6.36 and 6.48 MeV (1971VA34; p_{1}), 13.0, 14.0, 15.0, 21.35 and 30.3 MeV (1973VO02; p_{0}, p_{2}), 17.0, 21.0, 25.0, 29.1 (1973MO01; p_{0}, p_{2} and p to ^{9}Be*(3.1)), 33.6 MeV (1970KU1D; p_{0}), 46 MeV (1967SA13, 1967VE01; p_{0}, p_{2} and p to ^{9}Be*(11.3, 14.4, 16.7, 17.5)), 49.75 MeV (1971MA13, 1971MA44; p_{0}, p_{2} and p to ^{9}Be*(6.4)), and 100 MeV (1966MA38, 1968LI1C; p_{0}, p_{2} and p to ^{9}Be*(4.7, 6.8)). The elastic angular distributions show pronounced diffraction maxima characteristic of the optical model. See (1973MO01) for a discussion of optical model parameters. (1973VO02), in coupled channels analysis, find that a quadrupoledeformed optical model potential with a deformation parameter β = 1.1 [see also (1967SA13)] provides an improved description of the elastic data and a good fit to the p_{2} data [to ^{9}Be*(2.4)]. 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): see also the discussions in (1960SP08, 1971JE03) and in (1966LA04). The energy of ^{9}Be*(2.4) is given as 2433 ± 5 (1951BR72), 2434 ± 5 (1956BO18), 2432 ± 4 (1955GO48), 2430 ± 5 keV (1960SP08). ^{9}Be*(3.1) has a width of 250 ± 5 keV (1960SP08): E_{x} = 3.03 ± 0.03 MeV (1956BO18), 3.04 ± 0.05 MeV (1960SP08), J^{π} = 3/2^{+}, 5/2^{+}. 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] (1956BE14, 1965HA17). See also Table 9.8 (in PDF or PS) in (1966LA04). (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) in this reaction is consitent 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 discussion in (1966LA04). See also (1966MA38). See also (1965HU10, 1971HU1A, 1971SC1N) and (1968GL1A, 1968NE1A, 1968NE1B, 1968SE1B, 1969NE1A, 1969NE08, 1969WA11, 1970MA04, 1970MA38, 1971BA87, 1971IN05, 1971RA36, 1972SO03, 1973GU08, 1973HU05; theor.).
The summed proton spectrum (reaction (a)) shows two peaks with Q = 16.4 ± 0.3 and Q = 25.4 ± 0.5 MeV, corresponding to removal of a pproton and an sproton respectively, and a third peak of uncertain assignment with Q = 32.3 ± 0.6 MeV (probably due to unresolved states) (1966TY01: E_{p} = 460 MeV). See also (1966LA04), (1966WA12, 1968PE1A), (1965BE1E, 1966JA09, 1966JA1A, 1967BE1Q, 1967JA1E, KO67Q, 1968JA1G, 1969KO1J; theor.) and ^{8}Li. For reaction (b) see (1966LA04) and (1973KO1M). Reaction (c) is characterized by a sequential mechanism at low energies and by a quasi elastic scattering mechanism at higher energies. At E_{p} = 26.0, 35.0, 46.8 and 57 MeV the data are consistent with quasi free scattering of the incident protons by zeromomentum αparticle clusters in ^{9}Be: the probability of finding such clusters at these four energies is determined to be 0.166, 0.099, 0.124 and 0.09, respectively (1968RO19, 1970QU1C, 1972QU01). See also (1967TA1C, 1969YA1B, 1970GO12, 1973WO1E), (1969HO1K, 1971GA1J) and (1973HO30; theor.). For reaction (d), see (1969WI1F, 1970TH1F, 1971HU1A, 1973MI1J) and (1967BE1Q; theor.). For reaction (e) see (1969KO1G). See also (1968KO1E, 1969ED01).
Elastic scattering has been studied at many energies in the range E_{d} = 7.8 to 27.7 MeV: see (1966LA04). Elastic angular distributions are also reported for E_{d} = 1.1 to 2.5 MeV (1968MA1H), 4.5 to 6.0 MeV (1970PO03), 5.00 to 7.00 MeV (1971DJ02), 11.8 MeV (1967FI07; also d_{2}), 12.8 MeV (1973VA08; d_{1}), 13.6 MeV (1968VE11, 1968VE1C, 1970VE06, 1972MA47), 14.35 MeV (1966NG1A; also d_{2}), 15.0 MeV (1969AR1B), 15.8 MeV (1966CO24; also d_{2}) and 410 MeV (1960BU25; forward angles). For optical model parameters see discussions in (1966CO24, 1967FI07). Inelastic deuteron groups have been observed 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 (1963ST1A, 1969VE09, 1970EL16, 1973ZW1A; theor.) and ^{11}B.
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, 6, 8, 10, 15 and 18 MeV (1969PA11), 6.0 and 8.0 MeV (1967EA01), 13.2, 20.4, 22.2 and 27.0 MeV (1972BU30), 22.7 and 32.3 MeV (1965AR1E), and 217 MeV (1973WI07). See also (1970BA1P). For optical model parameters see discussions in (1972BU30, 1973WI07). 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) (1968BA1E, 1969BA06). See also (1968HO1C, 1968PA1P, 1969HO27; theor.), (1966LA04) and reaction 28 in ^{6}Li.
Elastic scattering has been studied at many energies for E_{α} = 9.5 to 48 MeV: see (1966LA04). Recent measurements of the angular distributions of α_{0} are reported at E_{α} = 8.76, 9.27 and 10.13 MeV (1967BR1F), 28.5 MeV (1967FU08; also α_{2}, and partial angular distributions for α_{1} and α_{3}) and 104 MeV (1969HA14, 1970HA1G, 1972DE01, 1972DE02). 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 the 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 group corresponding 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: E_{α} = 48 MeV) and (1967FU08: E_{α} = 28.5 MeV). Analysis based on the rotational model leads to a deformation coefficient β_{2} = 0.46 (1959BL31), 0.34 ± 0.01 (1964GR39). See also (1966GR1E, 1966GR1F, 1968LI1E, 1970WO1B, 1972DM01, 1972RA34). The summed αspectra from reaction (b) show a peak corresponding to quasielastic scattering leaving ^{5}He in the ground state. The angular distribution peaks at the angle corresponding to a zeromomentum αcluster. The probability of formation of such clusters is 7^{+13}_{5}% (1969PI11, 1970PI1D: E_{α} = 55 MeV). See also (1965YA02, 1968YA02, 1969DO02, 1969DO03) and ^{5}He. The reaction cross section has been measured at E_{α} = 42.8 and 49.2 MeV by (1971GU15). See also (1965HI1B, 1965KU1B, 1966HI1A, 1967ME1C, 1968BA1H, 1968TA1K, 1969BA1J, 1970MI12, 1972AV04, 1972HI16; theor.) and (1971GA1J). 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, 3.0) (1972OB01). See also (1971GE09, 1973GE1J, 1973WE03).
Elastic angular distributions have been measured at E(^{6}Li) = 24 MeV (1968DA20) and E(^{7}Li) = 24 MeV (1972WE08). See also (1970LK1A; theor.) for reaction (b).
Elastic scattering angular distributions have been obtained at E(^{12}C) = 12, 15, 18 and 21 MeV. The neutron spectroscopic factor for ^{9}Be is 0.84 (1970BA49).
Elastic angular distributions have been measured at E(^{14}N) = 25 MeV (1966OE1A) and 27.3 MeV (1959HA28). See also (1966LA04), (1969BR1D) and (1965BO37).
Elastic angular distributions have been reported at E(^{16}O) = 15, 18, 21.5 and 25 MeV (1970BA49) and 30 MeV (1969KR03), and at E(^{18}O) = 12.1, 16 and 20 MeV (1971KN05).
Forward angular distributions have been obtained at E_{d} = 15.0 MeV for the tritions 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 ^{10}B.
See (1969BA1F; theor.) and ^{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 shellmodel predictions (1965VA05). See also (1966GO1D), (1966WE1B, 1971MI12), (1966LA04) and ^{11}B in (1975AJ02).
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 (1965BE1E, 1966JA09, 1966JA1A, 1967JA1E, 1967KO1B, 1968JA1G; theor.), ^{10}B and (1966LA04).
Angular distributions of the ^{3}He groups corresponding to ^{9}Be*(0, 2.4) have been measured at E_{d} = 11.8 MeV (1966BA21, 1967FI07: S_{exp} = 0.76 and 0.66, respectively) and at 28 MeV [(1971IN1C); (1968GA13: ground state only)]. The data are very similar, as predicted, to those obtained in the mirror reaction: see reaction 12 in ^{9}B. See also (1965SY02, 1971WA1K, 1972WA1M).
At E_{t} = 12.9 MeV α groups 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).
The ground state angular distribution has been measured at E(^{14}N) = 27.5 MeV (1962NE01).
See (1968OK06).
The angular distribution of the ground state group 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). 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): Γ_{cm} = 224 ± 25 keV (1958KA31, 1966PU02). The energy of ^{9}Be*(2.4) is 2422 ± 5 keV (1951VA08), 2431 ± 6 keV (1954EL10), 2424 ± 5 keV (1956BO18). The 5/2^{+} state is at E_{x} = 3.02 ± 0.03 MeV (1955LE36), 3.05 ± 0.03 MeV (1956BO18): Γ_{cm} = 257 ± 25 keV (1958KA31, 1966PU02). Angular distributions are reported at E_{d} = 0.39 to 0.7 MeV (1965SA15; α_{0}, α_{2}), 0.8 to 2.5 MeV (1968CO31; α_{0}, α_{2}) and at 12.6 MeV (1966DR04; α_{0}, α_{2}). See also (1966ME1E; theor.). The ratio of the γdecay width to the total width, Γ_{γ}/Γ, of ^{9}Be*(2.4) is (1.16 ± 0.14) × 10^{4}. Since Γ_{γ} is known from (e, e') [see Table 9.8 (in PDF or PS)], Γ = 1.03 ± 0.18 keV. For ^{9}Be*(1.7), Γ_{γ}/Γ ≤ 2.4 × 10^{5} (1966PU02). 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 ^{9}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 ^{8}Be, ^{13}C in (1976AJ04) and (1966LA04).
See (1968OK06).
Angular distributions of the α_{0} group have been measured at E_{n} = 14.1 MeV (1969HS02, 1969KI02), 13.9 and 15.6 MeV (1968BR21), and 14.8 to 18.8 MeV (1971SA31). (1968BR21, 1969HS02) also report the population of ^{9}Be*(1.7, 2.4, 3.1). Reaction (b) at E_{n} = 13 to 18 MeV involves ^{9}Be*(2.4) (1966MO05). See also (1965MO09, 1966MI1D, 1968BE1J, 1969KA1D, 1969LO1D, 1971DO1K, 1971FA04), (1966CI1A, 1966LA04), (1967EL1D, 1968CH1J; theor.), ^{12}C in (1975AJ02), and ^{13}C in (1976AJ04).
Angular distributions have been obtained for the transitions to ^{7}Be*(0, 0.43) + ^{9}Be(0) (1972RU03; 42 MeV). See also (1971LE33).
See ^{13}C in (1976AJ04).
See (1971BR07).
A partial angular distribution involving the transition to ^{6}Li(0) + ^{9}Be(0) has been measured at E_{d} = 14.6 MeV (1966DE09).
The angular distribution involving the transition to ^{11}C(0) + ^{9}Be(0) has been measured at E_{α} = 42 MeV (1972RU03).
