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9Be (2004TI06)

(See Energy Level Diagrams for 9Be)

GENERAL: References to articles on general properties of 9Be published since the previous review (1988AJ01) are grouped into categories and listed, along with brief descriptions of each item, in the General Tables for 9Be located on our website at (nucldata.tunl.duke.edu/nucldata/General_Tables/9be.shtml).

See also Table 2 preview 2 in (1988AJ01) [Electromagnetic Transitions in A = 5-10] (in PDF or PS), Table 9.2 preview 9.2 [Table of Energy Levels] (in PDF or PS) and Table 9.3 preview 9.3 [Electromagnetic transitions in 9Be] (in PDF or PS).

μ = -1.1778 ± 0.0009 μN: see (1978LEZA);

Q = 52.88 ± 0.38 mb: see (1967BL09, 1991SU05, 2001STZZ).

Interaction cross sections of 9Be with Be, C, and Al targets have been measured at E = 790 MeV/A yielding an interaction nuclear radius of 9Be is 2.45 ± 0.01 fm (1985TA18) [see also for derived nuclear matter, charge and neutron matter r.m.s. radii]. See (2001OZ04) for references to derivations of radii for 9Be.

The decay 9LiΛ → π- + 9Be* → π- + p + 8Li appears to take place via a T = 3/2 state of 9Be at Ex = 18.6 ± 0.1 MeV (Γ ≤ 300 keV) that appears to be an analog of the 4.3 MeV level of 9Li (1985PN01).

For a discussion of the structure and widths of levels in 9Be and 9B, see the general discussion of 9B.

1. (a) 6Li(t, n)8Be Qm = 16.0236 Eb = 17.6890
(b) 6Li(t, p)8Li Qm = 0.80079
(c) 6Li(t, n)4He4He Qm = 16.115451

The 0° differential cross section for reaction (a) increases monotonically between Et = 0.10 and 2.4 MeV. A resonance has been reported at Et = 1.875 MeV (9Be*(18.94)). The excitation function for 8Li (reaction (b)) increases monotonically for Et = 0.275 to 1.000 MeV. See (1974AJ01) for references. In the range Et = 2 to 10 MeV the total cross section for reaction (b) shows a broad structure [Γcm = 1.5 MeV] at Et = 4.2 MeV (9Be*(20.5)) (1986AB04). Yields and angular distributions for reaction (c) have been measured at Et = 2 to 4.5 MeV (1984LIZY). See also (1984AJ01) for other channels and (1984KR1B).

2. 6Li(3He, π+)9Be Qm = -121.8998

The energy dependence of the cross section for population of 9Beg.s. has been measured at E(3He) = 235 to 283 MeV (1984WI06).

3. 6Li(α, p)9Be Qm = -2.1249

Angular distributions of p0 have been measured at Eα = 10.2 to 14.7 MeV and at 30 MeV: see (1974AJ01). Differential cross sections were measured at Eα = 26.7 MeV (1990LI37) in a study of exchange processes. See also (1987BI1C) and (1983BE51).

4. 7Li(d, γ)9Be Qm = 16.6959

For Ed = 0.1 to 1.1 MeV, a resonance in the yield of capture γ-rays is observed at Ed = 360.8 ± 0.3 keV (1987ZI01), 360.7 ± 1.8 keV (1986BE33), corresponding to the excitation of 9Be*(16.97), the second T = 3/2 state [Jπ = 1/2-]: see Table 9.5 preview 9.5 (in PDF or PS). Another measurement of the total width of this state determined Γ = 389 ± 10 eV; see (1992KI05). The reduced width for the isospin "forbidden" deuteron breakup is 3.9 × 10-4 relative to the Wigner limit (1992KI05). See also (1984AJ01). The differential cross section and vector analyzing power were measured by (1993SC19) at Ed = 6 MeV.

5. (a) 7Li(d, n)8Be Qm = 15.0306 Eb = 16.6959
(b) 7Li(d, α)5He Qm = 14.229
(c) 7Li(d, n)4He4He Qm = 15.12239

The yield of neutrons has been measured for Ed = 0.2 to 23 MeV [see (1979AJ01)] and at Ed = 0.19 to 0.55 MeV (1987DA25). See also (1983SZZY). Polarization measurements have been carried out at Ed = 0.64 MeV and 2.5 to 3.7 MeV [see (1974AJ01)] and at 0.40 and 0.46 MeV (1984GA07; n0). Resonances are reported at 0.36, 0.68 and 0.98 MeV: see Table 9.3 preview 9.3 (in PDF or PS) in (1974AJ01). See also (1985CA41; astrophys.) and the measurements at Ed = 195 - 550 keV of (1987DA25). Neutron yields for 40 MeV deuterons on 7Li thick targets were measured by (1987SC11). See also the measurements at Ecm = 0.7 - 2.3 MeV (1996BO27) and the fusion calculations of (2000HA50).

The yields of α-particles have been measured for Ed = 0.25 to 3.0 MeV: see (1974AJ01, 1979AJ01). Resonances are reported at Ed = 0.75, 1.00 and 2.5 MeV; the latter is broad: see Table 9.3 preview 9.3 (in PDF or PS) in (1979AJ01). See also (1983SZZY), (1986DIZT, 1987LE1F; applied) and (1984KR1B). In recent work, measurements of astrophysical S factors at Ecm = 57 - 141 keV have been reported by (1997YA08). See also the calculations described in (2000HA50).

6. 7Li(d, p)8Li Qm = -0.19228 Eb = 16.69594

Excitation functions and cross sections have been measured for Ed = 0.29 to 7 MeV [see (1974AJ01, 1979AJ01, 1984AJ01)] and 0.60 to 0.95 MeV (1983FI13). See also (1983SZZY, 1986AB04). Deuteron energies (in MeV) and widths [Γlab in brackets in keV] of resonances reported are: Ed = 0.360 ± 0.003 [< 0.5], 0.776 ± 0.007 [250], 1.027 ± 0.007 [60], 2.0 [broad], 2.375 ± 0.050, 3.220 ± 0.050 [400 ± 100] and ≈ 4.8 MeV corresponding to 9Be*(16.975) [see also Table 9.5 preview 9.5 (in PDF or PS)], 17.298, 17.493, (18.5), 18.54, 19.20, 20.4): for references see Table 9.3 preview 9.3 (in PDF or PS) in 1979AJ01, and Table 9.3 preview 9.3 (in PDF or PS) in 1984AJ01. The total cross section at the Ed = 0.78 MeV resonance is important because it serves as a normalization for the 7Be(p, γ)8B reaction: the "best" value suggested by (1983FI13) is 157 ± 10 mb. See also (1986BA38) and (1974AJ01, 1984AJ01) for the earlier values. At E(7Li) = 12.2 ± 1.3 MeV [corresponding to Ed = 3.5 MeV] the cross section is reported to be 155 ± 20 mb (1985HA40).

At the peak of the Ed = 0.78 MeV resonance, σ = 143.6 ± 8.9 mb from the proton yield and σ = 151 ± 20 mb from the β-delayed α activity of the residual 8Li nucleus (1996ST18). In (1998WE05), a value σ = 155 ± 8 mb was obtained, backscattering effects were examined, and the consequences for the 7Be(p, γ) cross sections were discussed. The 7Li(d, p) yield for Ed = 0.4 - 1.8 MeV was measured by (1998ST20) to deduce corrections due to recoil loss. See also the compilation and analysis of astrophysical S-factor data and calculations in (1998AD12).

7. 7Li(d, d)7Li Eb = 16.69594

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), and at Ed = 9.05 MeV (1980YE02).

8. 7Li(d, t)6Li Qm = -0.99306 Eb = 16.69594

The cross section 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). Differential cross sections measured at Ed = 30.7 MeV were reported in (1987BO39). An analysis of data from this reaction at Ed = 8 - 50 MeV is discussed in (1995GU22).

9. 7Li(3He, p)9Be Qm = 11.2025

Observed proton groups are displayed in Table 9.6 preview 9.6 (in PDF or PS). The parameters for the particle and γ-decay of observed states are displayed in Table 9.4 preview 9.4 (in PDF or PS) and Table 9.7 preview 9.7 (in PDF or PS). Angular distributions have been reported in the range E(3He) = 0.9 to 14 MeV [see (1974AJ01, 1979AJ01)] and at E(pol. 3He) = 14 and 33 MeV (1983LE17, 1983RO22; p0). See also 10B, (1984ME11) and (1986SC35; applications).

In more recent work cross sections σ(Ep, θ) were measured at Ecm = 0.5 - 2 MeV, and the astrophysical S-factor was deduced (1990RA16). Polarization observables were measured at E(3He) = 4.6 MeV and analyzed by DWBA (1995BA24). See (1993YA01) for S-factor calculations and discussions of astrophysical implications. See also the earlier theoretical work of (1988KH11) on time-reversal violating amplitude features.

10. 7Li(α, d)9Be Qm = -7.1506

Angular distributions of d0, d1 and d2 have been reported at Eα = 30 MeV: see (1974AJ01). See also (1983BE51).

11. 7Li(6Li, α)9Be Qm = 15.2221

Angular distributions of the α-groups to 9Be*(0, 2.43, 6.76) have been measured at E(7Li) = 78 MeV (1989GL03). For the excitation of 4He* see (1987GLZX, 1987GLZY; E(6Li) = 93 MeV). For the earlier work see (1974AJ01).

12. 9Li(β-)9Be Qm = 13.6067

9Li decays by β- emission with τ1/2 = 178.3 ± 0.4 msec and Pn = 50.8 ± 0.9% to several 9Be states: see reaction 1 in 9Li and Table 9.8 preview 9.8 (in PDF or PS). A series of studies at ISOLDE (1981LA11, 1990NY01, 2003PR11) have measured β - α coincidences and established the existence of transitions with large B(GT) values to 9Be*(11.28) and/or 9Be*(11.81). The information in Table 9.8 preview 9.8 (in PDF or PS) is based largely on the results of (1990NY01) and an analysis by (1993CH06). The most recent study (2003PR11) finds that the low-energy decays are mostly to 9Be*(11.81) with a B(GT) value of 8.5 ± 1.5, that a spin assignment of 5/2- is favored, and note that the B(GT) value is a factor of 4.4 ± 1.0 larger than that of the mirror transition in 9C (see reaction 10 in 9B). Such a large asymmetry for a strong transition and the magnitude of the B(GT) value for 9Li decay are difficult to understand theoretically. The latter difficulty is highlighted by the fact that, in the limit of good supermultiplet symmetry only 1/3 of the GT sum-rule strength 9(gA/gV)2 eff [see footnote c in Table 9.8 preview 9.8 (in PDF or PS)] goes to 5/2- states.

13. (a) 9Be(γ, n)8Be Qm = -1.6654
(b) 9Be(γ, α)5He Qm = -2.467
(c) 9Be(γ, n)4He4He Qm = -1.5736

As noted in the previous review (1988AJ01), "the photoneutron cross section has been measured from threshold to 320 MeV: see Table 9.6 preview 9.6 (in PDF or PS) in (1966LA04), (1979AJ01) and (1988DI02). 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) and (1987KU05). The cross section then decreases slowly to 1.2 mb at 40 keV above threshold. From bremsstrahlung studies, peaks in the (γ, n) cross section are observed corresponding to Ex = 1.80 and 3.03 MeV".

Subsequently (1992GO27) measured the photoneutron yield and mean energies of photoneutron spectra from bremsstrahlung photons. The reaction cross section for energies from threshold to 20 MeV was extracted. Resonances were observed corresponding to Ex = 1.68 MeV (1/2+), 2.43 MeV (5/2-), and 3.05 MeV (5/2+) in 9Be. See Table 1 in (1992GO27) for resonance parameters. In other work (2001UT01, 2002SU19), laser-induced Compton backscattering photons with Eγ = 1.78 - 6.11 MeV were used to measure the photoneutron cross section resonance parameters for the 9Be 1/2+, 5/2- and 5/2+ states; see Table 9.9 preview 9.9 (in PDF or PS). The radiative widths in Table 9.9 preview 9.9 (in PDF or PS) are not in good agreement with those from low-energy electron scattering listed in Table 9.3 preview 9.3 (in PDF or PS). Also, the width given for the 5/2+ state is roughly twice the accepted width of 282 ± 11 keV in Table 9.2 preview 9.2 (in PDF or PS); using the accepted width while maintaining a fit to the peak (γ, n) cross section would reduce Γγ by almost a factor of two and into the range of the values from (e, e') listed in Table 9.3 preview 9.3 (in PDF or PS). Shell-model calculations give a stable B(M1)(↓) ≈ 1 W.u. (Γγ ≈ 0.45 eV) for the broad 1/2- state at 2.78 MeV implying significant (γ, n) cross section underlying the energy region of interest. A one-level R-matrix analysis of the Eγ = 1.6 - 2.2 MeV cross section is described in (2000BA21). The energy at which the cross section due to the 1/2+ state peaks and the FWHM of the peak vary somewhat for different fits to a number of data sets but are relatively stable. However, the extracted B(E1)(↓) values vary considerably and generally correspond to larger Γγ's than those listed in Table 9.3 preview 9.3 (in PDF or PS) and Table 9.9 preview 9.9 (in PDF or PS). For theoretical calculations of the low-energy (γ, n) cross section see (1998EF05, 1999EF01, 2002IT07). See also the calculation of 9Be Coulomb dissociation (1994KA25) and polarized neutron production by magnetic Bremsstrahlung gamma rays (1997ER03).

(1988AJ01) notes that "at higher energies, using monoenergetic photons, the (γ, n) 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, (17.3), (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. At Eγ = 1.58 MeV, the cross section for reaction (c) is 0.40 ± 0.18 μb (1983FU13). For the electroproduction and photoproduction of helium nuclei for Ee = 100 to 225 MeV see (1986LI22). For hadron production at high energies see (1983AR24)". See also the earlier work cited in (1988AJ01).

14. (a) 9Be(γ, p)8Li Qm = -16.8882
(b) 9Be(γ, n + p)7Li Qm = -18.9205
(c) 9Be(γ, d)7Li Qm = -16.6959
(d) 9Be(γ, t)6Li Qm = -17.6890

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 early references. For momentum spectra of protons using tagged photons with Eγ = 360 - 600 MeV, see (1984BA09). See also (1984AJ01) and (1984HO24), and see the analysis for Eγ = 200 - 420 MeV by (1988TE04).

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 6Lig.s.. The total integrated cross section for [(γ, p) + (γ, pn) + (γ, d) + (γ, t)] is 33 ± 3 MeV · mb. Calculations for reaction (b) at Eγ = 247 MeV are presented in (1993BO35). Resonances in the (γ, d) and (γ, t) cross sections corresponding to 9Be*(26.0 ± 0.2) and 9Be*(32.2 ± 0.3), respectively, have been reported: see (1974AJ01). A recent measurement and cluster-model analyses for reactions (a), (c), (d) for Eγ = 21 - 39 MeV are described in (1999SH05). For momentum spectra of deuterons and tritons at Eγ = 360 - 600 MeV see (1986BA07). Cross sections have been measured in the region of the Δ(1232) resonance by (1984HO09) [(γ, pn), (γ, 2p)], (1987KA13) [(γ, p), (γ, pn), (γ, 2p)] and (1986AR06) [(γ, π0)]. For a high energy study of hadron production see (1983AR24). See also (1986MC1G), (1985HO27, 1985MA1G) and the calculations of (1983TR04, 1986HO11, 1987LU1B, 1988DU04).

15. 9Be(γ, γ)9Be

The ground state radiative widths of the Ex = 14.393 and 16.975 MeV T = 3/2 levels of 9Be have been measured in a resonant absorption experiment (1992KI05) that updates the results of (1986ZI01, 1987ZI01). The results are Γγ0 = 5.9 ± 0.8 eV and Γγ0 = 16.9 ± 1.0 eV for Ex = 14.393 and 16.975 MeV, respectively. See Table 9.4 preview 9.4 (in PDF or PS) and Table 9.5 preview 9.5 (in PDF or PS). With Ebrem = 31 MeV eight resonances in (γ, γ') were reported for 17.4 < Ex < 29.4 MeV (1984AL22).

16. (a) 9Be(e, e)9Be
(b) 9Be(e, en)8Be Qm = -1.6654
(c) 9Be(e, ep)8Li Qm = -16.8882
(d) 9Be(e, eα)5Li Qm = -2.757

< r2 >1/2 = 2.519 ± 0.012 fm (1973BE19, 1979AJ01);

Q = 5.86 ± 0.06 fm2 (1991GL02);

b = 1.5-0.2+0.3 fm (1973BE19, 1979AJ01) [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] (1975LA23, 1979AJ01).

The previous review (1988AJ01) observed that: "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. Inelastic scattering populates a number of levels: see Table 9.8 preview 9.8 (in PDF or PS) in (1988AJ01). At Ee = 45 and 49 MeV 9Be*(1.68) has a strongly asymmetric line shape, as expected from its closeness to the 8Be + n threshold. The form factor is dominated by a 0p3/2 → 1s1/2 particle-hole transition. 9Be*(2.43) is strongly excited (1987KU05). Form factors have also been measured for 9Be*(0, 14.39, 16.67, 16.98, 17.49) by (1983LO11; Ee = 100.0 to 270.2 MeV). See also (1985HY1A, 1986MA48, 1987HY01). (1984WO09) suggests that the T = 1/2 states [9Be*(16.67, 17.49)] have Jπ = 5/2+ and 7/2+, respectively, and that they have large parentage amplitudes with 8Be*(16.6 + 16.9) [Jπ = 2+], rather than with 8Beg.s.. See (1974AJ01, 1979AJ01, 1984AJ01).

In a more recent study (1991GL02), electrons at energies between 110 and 360 MeV were used along with detailed line-shape analysis to extract cross sections for states at Ex = 0, 1.68, 2.43, 3.05, 4.70, 6.38, 6.76, 11.28, and 13.79 MeV, and for momentum transfers between 1.0 and 2.5 fm-1. See Table 9.10 preview 9.10 (in PDF or PS).

A previously unknown state at 6.38 MeV was isolated from the known 6.76 MeV state in both the (e, e') data of (1991GL02) and the (p, p') data (1991DI03) using the dependence of the peak position upon momentum transfer. On the basis of the form factor the 6.38 MeV state replaces the 6.76 MeV state as the 7/2- member of the ground state rotational band, and the 6.76 MeV state is identified with the lowest 9/2+ state predicted by the shell model. Results of these measurements are tabulated and compared with the shell model prediction in Table V in (1991GL02) and in Table 9.10 preview 9.10 (in PDF or PS) here.

An analysis of form factors to deduce vertex constants is described in (1991BE40). Harmonic scattering calculations are presented in (1992DE42).

For early work in the quasifree and Δ-resonance regions see references cited in (1988AJ01).

17. 9Be(π±, π±)9Be

The elastic scattering, and inelastic scattering to 9Be*(2.43, 6.76) have been studied at Eπ± = 162 and 291 MeV. Quadrupole contributions appear to be quite important for the elastic scattering at 162 MeV, but are much less so at the higher energy: see (1984AJ01) and see the General Table for 9Be located on our website at (nucldata.tunl.duke.edu/nucldata/General_Tables/9be.shtml). Calculations of threshold pion-nucleus amplitude by current algebra are discussed in (1989GE10). See also the diffraction theory calculations of the scattering process by (2000ZH50).

18. (a) 9Be(n, n)9Be
(b) 9Be(n, 2n)8Be Qm = -1.6654

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 9.7 preview 9.7 (in PDF or PS). Angular distributions have been measured at En = 3.5 to 14.93 MeV [see (1974AJ01, 1979AJ01, 1984AJ01)], at En = 7 to 15 MeV (1983DA22; n0), 11 to 17 MeV (1985TE01; n0, n2), 14.6 MeV (1985HA02, 1986HAYU; n0) and 14.7 MeV (1984SH01; n0, n2) as well as at En = 9 to 17 MeV (1984BY03; n0, n2; see also for transition to 9Be*(6.76)). See also 10Be, and other early work cited in (1988AJ01).

Spin-dependent scattering lengths were measured at low energies (1987GL06) by a pseudomagnetic precession method, and cross sections were measured at En = 1 - 10 MeV (1989SU13) and En = 21.6 MeV (1990OL01). Calculations and analysis for 9Be(n, n) are reported in (1988FE06, 1991IO01, 1996CH33, 2001BO10).

For reaction (b) the n - n scattering length was measured at En = 10.3 MeV (1990BO43). A thick target neutron spectrum was used in a measurement of the reaction cross section by (1994ME08). See also the analysis and model calculations for 9Be(n, 2n) at En = 5.9 MeV (1988BE04).

19. (a) 9Be(p, p)9Be
(b) 9Be(p, p')9Be*

The previous review (1988AJ01) summarized the information available from the reaction as follows: "Elastic and inelastic angular distributions have been studied at many energies in the range Ep = 2.3 to 1000 MeV [see (1974AJ01, 1979AJ01, 1984AJ01)], at Ep = 2.31 to 2.73 MeV (1983AL10; p0), 11 to 17 MeV (1988AJ01; p0) and 1 GeV (1985AL16; p0) as well as at Epol. p = 200 MeV (1985GLZZ; p0) and 220 MeV (1985RO15; p0, p2). The elastic distributions show pronounced diffraction maxima. A quadrupole-deformed optical-model potential is necessary to obtain a good fit to the p0 and p2 angular distributions: see (1974AJ01). The spin-flip probability at Epol. p = 31 MeV is ≈ 0 for the p2 group, which is expected in view of the collective nature of the transition (1981CO08)."

"The structure corresponding to 9Be*(1.7) is asymmetric, as expected: see reaction 16 and Table 9.8 preview 9.8 (in PDF or PS) in (1988AJ01) for its parameters. [At Ep = 13 MeV the spectra are dominated by 9Be*(2.43) (1987KU05)]. 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 and Γ in MeV) Ex = 4.8 ± 0.2, 6.76 ± 0.06 [Jπ = (1/2+, 5/2+, 7/2+) (but see below), Γ = 1.2 ± 0.2], 7.94 ± 0.08 (Γ ≈ 1), 11.3 ± 0.2 (Γ ≈ 1), 14.4 ± 0.3 (Γ ≈ 1), 16.7 ± 0.3, 17.4 ± 0.3, 19.0 ± 0.4, 21.1 ± 0.5 and 22.4 ± 0.7 [the five highest states are all broad]. 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."

In an experimental and theoretical study of 9Be structure (1991DI03), cross section and analyzing power measurements made with 180 MeV protons provided data for 24 states below Ex = 21 MeV. Detailed line shape analysis was used to isolate several broad states. In particular the strong resonance at 6.76 MeV (1988AJ01) was separated into two levels identified as the 7/2- member of the ground state rotational band at 6.38 MeV and the 9/2+ weak-coupling state at 6.76 MeV. Level energies, suggested assignments and widths are summarized in Table 9.11 preview 9.11 (in PDF or PS). Transition densities were fitted to (p, p') data and compared with results from (e, e') data (1991GL02). Shell model calculations in 0ℏω and 1ℏω model space were performed and used in making suggested assignments (1991DI03).

In other experimental work, measurements have been reported for cross sections and polarization observables at Ep = 135 MeV (1988KE04, 1989KE03), and at Ep = 54.7 and 74.7 MeV (1994DE23). The data from these experiments were analyzed with other data for 30 < Ep < 220 MeV in terms of a variety of optical model and coupled-channel analyses to calculate final-state interaction effects for proton knockout reactions on 10B (1994DE23). Microscopic coupled-channel calculations for the ground-state rotational band of 9Be and 100 < Ep < 500 MeV have been made using the folding model and density-dependent interactions (1992KE05). Elastic scattering cross sections have been reported at Ep ≤ 2.66 MeV (1994WR01), and application-related scattering cross sections at Ep = 2.3 - 2.7 keV (1988LA07) and Ep = 2.4 - 2.7 MeV (1994LE18).

Other theoretical work published since the previous review (1988AJ01) includes geometric model calculations (1990HU09); construction of interaction potentials from phase shifts (1996KU14); Glauber-Sitenko theory calculations for Ep = 0.22, 1 GeV (1996ZH31); microscopic-model analysis for Ep = 200 MeV (1997DO01); Glauber-model calculations for Ep = 0.22, 1.0 GeV (1997ZH39); calculations of polarization features for Ep = 0.22, 1.0 GeV (1998ZH02); and diffraction theory calculations for Ep = 0.16 - 1.04 GeV (2000ZH50).

20. (a) 9Be(p, 2p)8Li Qm = -16.8882
(b) 9Be(p, pd)7Li Qm = -16.6959
(c) 9Be(p, p + n)8Be Qm = -1.6654
(d) 9Be(p, p + t)6Li Qm = -17.6890
(e) 9Be(p, p + 3He)6He Qm = -21.1787
(f) 9Be(p, pα)5He Qm = -2.467

The reactions (p, 2p)X and (p, pd)X have been studied at Ep = 300 MeV (1983GR21, 1984HE03). For reactions (a) and (c) see also 8Li, 8Be (1985BE30, 1985DO16; 1 GeV) and (1984AJ01). Reaction (c) at Ep = 10 - 24 MeV involves 9Be*(3.0, 4.7): see (1984AJ01). See also (1984WA21). For reactions (b) and (d) at Ep = 58 MeV see 7Li and 6Li in (2002TI10), and (1984DE1F, 1985DE17). For reactions (e) and (f) see (1985PAZL; Epol. p = 70 MeV). The (p, pα) process (reaction (f)) has been studied at Ep = 150.5 MeV (1985WA13), at 200 MeV (1989NA10), and at 296 MeV (1998YO09). Alpha cluster knockout spectroscopic factors were deduced. For inclusive proton spectra yields see (1985SE15). Inclusive differential cross sections for 4,6,8He and 6,7,8Li formation by 1 GeV protons on 9Be were measured by (1994AM09). Cross section and proton and neutron spectra for reactions (a) and (c) at Ep = 70 MeV were studied by (2000SH01). See also the earlier work cited in (1988AJ01).

21. 9Be(d, d)9Be

Angular distributions have been measured in the range 1.0 to 410 MeV [see (1974AJ01, 1979AJ01, 1984AJ01)] and at Ed = 2.0 to 2.8 MeV (1983DE50, 1984AN16). See also 11B in (1990AJ01).

Inelastic groups have been reported to 9Be*(1.7, 4.7, 6.8) and to states with Ex = 2431.9 ± 7.0 keV and 3040 ± 15 keV (Γ = 294 ± 20 keV): see (1974AJ01). Measurements at Ed = 6.7 - 7.5 MeV of differential cross sections for inelastic groups to 9Be*(2.43) and DWBA analysis were reported by (1989SZ02). An analysis by (1989VA17) of (d, d') data at Ed = 13.6 MeV found evidence for kinematic focusing of the products of 3-particle decay of 9Be*(2.43). An optical-model description for Ed = 4 - 11 MeV is discussed in (1993AB10).

22. (a) 9Be(t, t)9Be
(b) 9Be(t, n + t)8Be Qm = -1.6654

Angular distributions of elastically scattered tritons have been measured at Et = 2.10 MeV and at Epol. t = 15 and 17 MeV: see (1974AJ01, 1984AJ01). A more recent analysis by a strong absorption model of cross sections measured at Et = 17 MeV is reported in (1994SO26). Reaction (b) at 4.2 and 4.6 MeV proceeds via 9Be*(2.4): see (1974AJ01).

23. (a) 9Be(3He, 3He)9Be
(b) 9Be(3He, 2α)4He Qm = 19.0041

Angular distributions have been studied for E(3He) = 1.6 to 46.1 MeV and at 217 MeV [see (1974AJ01, 1979AJ01, 1984AJ01)]. At E(3He) = 39.8 MeV, 9Be*(1.7, 2.4, 3.1, 4.7, 6.8, 14.4) are populated. Data for E(3He) = 50, 60 MeV were analyzed by (1992AD06), and rainbow effects were observed. Differential cross sections for E(3He) = 60 MeV were measured by (1993MA48, 1996RU13). Measurements and analysis of the α-particle spectra from the decay of 9Be*(2.43) populated in the inelastic scattering reaction with E(3He) = 40.5 MeV are reported in (1990BO51). An optical model description of the elastic scattering is discussed in (1987TR01).

Reaction (b) has been studied in a kinematically complete experiment for E(3He) = 3 to 12 MeV (1986LA26) and 11.9 to 24.0 MeV (1987WA25). See also (1990BO51). For the earlier work see (1984AJ01).

24. (a) 9Be(α, α)9Be
(b) 9Be(α, 2α)5He Qm = -2.467

Angular distributions have been studied at many energies in the range Eα = 5.0 to 104 MeV [see (1974AJ01, 1984AJ01)] and Eα = 23.1 MeV (1984HU1D, 1985HU1B; α0, α2). 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). A coupled channel folding model analysis for data at Eα = 65 MeV is described in (1995RO21). See also (2000ZH38).

See also the multicluster model calculation of (1993KU21) and the calculations of levels and rotational bands using (α, α') data reported in (1997VO06). In application-related work backscattering cross sections were measured for Eα = 6.00 - 6.52 MeV (1996QI03), 0 - 5.3 MeV (1994LE18), 0.15 - 3.0 MeV (1994LI51). Related data were compiled and reviewed in (1991LE33, 1996ZH36). For reaction (b) see (1983ZH09; 18 MeV); Sα = 0.96 [see (1984AJ01)] and (1987WA25; E(3He) =12 to 24 MeV). A measurement of energy-sharing distributions at Eα = 197 MeV was reported in (1994CO16). Cluster knockout at Eα = 580 MeV was studied by (1999NA05). See also 8Be, (1987BU27, 1987KO1K) and (1984LI28, 1985SR01).

25. 9Be(6He, 6He)9Be

The cross section at E(6He) = 8.8 - 9.3 MeV was measured by (1991BE49).

26. (a) 9Be(6Li, 6Li)9Be
(b) 9Be(7Li, 7Li)9Be

Elastic angular distributions have been measured at E(6Li) = 4, 6 and 24 MeV and at E(7Li) = 24 and 34 MeV [see (1979AJ01)] as well as at E(6Li) = 32 MeV (1985CO09; also to 9Be*(2.43)) and 50 MeV (1988TRZY) and E(7Li) = 78 MeV (1986GLZV, 1986GLZU; also to 9Be*(2.43, 6.76)). More recently, measurements and analysis of complete angular distributions for elastic scattering and inelastic scattering to 9Be*(2.43) at Ecm = 7, 10, 12 MeV were reported by (1995MU01). See also the cross section measurements and optical model analysis for E(6Li) = 50 MeV (1990TR02) and the analyzing power measurements for elastic and inelastic scattering at E(6Li) = 32 MeV (1993RE08). Thresholds of non-Rutherford cross sections for ion-beam analysis were studied by (1991BO48). For the interaction cross section at E(6Li) = 790 MeV/A see (1985TA18).

For reaction (b), cross section measurements at E(7Li) = 63, 130 MeV and optical-model analyses are reported in (2000TR01). The α - 5He decay of 9Be excited states populated by E(7Li) = 52 MeV was studied by (1998SO05).

27. 9Be(9Be, 9Be)9Be

Elastic angular distributions have been obtained at E(9Be) = 5 to 26 MeV [see (1979AJ01, 1984AJ01)] and at 35 to 50 MeV (1984OM02; also to 9Be*(2.43)). See also (1985JA09). For yields and cross sections see (1984OM03, 1986CU02, 1988LA25). See also the application-related measurement at E(9Be) = 5.5 MeV (1988DA05). In more recent work, elastic scattering measurements at E(9Be) = 40 MeV were reported by (1992CO05). It was determined that the angular distribution data of (1984OM02) must be shifted forward by 5° cm. For the interaction cross section at E(9Be) = 790 MeV/A see (1985TA18).

28. (a) 9Be(10B, 10B)9Be
(b) 9Be(11B, 11B)9Be

Elastic angular distributions have been reported at E(10B) = 20.1 and 30.0 MeV (1983SR01). For yields and cross section measurements see (1983SR01, 1984DA17, 1986CU02). See also (1983DU13) and (1984IN03, 1986RO12). Differential cross sections were measured at E(10B) = 100 MeV (1997MU19, 2000TR01). Optical model parameters and values of the asymptotic normalization coefficients (ANC) for 10B → 9Be + p were deduced.

29. (a) 9Be(12C, 12C)9Be
(b) 9Be(13C, 13C)9Be

Elastic angular distributions have been measured for reaction (a) at E(12C) = 12, 15, 18 and 21 MeV and E(9Be) = 14 to 76.6 MeV [see (1979AJ01, 1984AJ01)] and 158.3 MeV (1984FU10) as well as at E(12C) = 65 MeV (1985GO1H; various 12C states). For yield and fusion cross-section measurements see (1983JA09, 1985DE22) and (1984AJ01). Angular distributions and excitations functions for elastic scattering and inelastic scattering to 9Be*(2.43) for Ecm = 10.9 MeV are reported in (1995CA26). Reorientation and coupling effects in the 9Be + 12C system were studied. See also the measurements and analysis for Ecm = 5.14 - 90.46 MeV of (2000RU02).

Elastic angular distributions for reaction (b) are reported for E(9Be) = 14 to 26 MeV: see (1984AJ01). Measurements and optical-model analysis for E(13C) = 130 MeV are reported in (2000TR01). For yield measurements see (1984DA17, 1986CU02). See also the earlier work cited in (1988AJ01).

30. 9Be(14N, 14N)9Be

Elastic angular distributions have been measured at E(14N) = 25 and 27.3 MeV: see (1974AJ01). For a fusion study see (1984MA28).

31. (a) 9Be(16O, 16O)9Be
(b) 9Be(18O, 18O)9Be

Elastic angular distributions have been reported in the range E(16O) = 15 to 30 MeV [see (1979AJ01)] and (1988WE17), at E(9Be) = 14, 20 and 26 MeV [see (1984AJ01)], 43 MeV (1985WI18) and 157.7 MeV (1984FU10), as well as at E(18O) = 12.1, 16 and 20 MeV [see (1974AJ01)]. See also the other references cited in (1988AJ01).

32. (a) 9Be(20Ne, 20Ne)9Be
(b) 9Be(24Mg, 24Mg)9Be
(c) 9Be(26Mg, 26Mg)9Be
(d) 9Be(27Al, 27Al)9Be
(e) 9Be(28Si, 28Si)9Be
(f) 9Be(39K, 39K)9Be
(g) 9Be(40Ca, 40Ca)9Be
(h) 9Be(44Ca, 44Ca)9Be

Elastic angular distributions have been measured for many of these reactions: see (1979AJ01, 1984AJ01). They have been studied on 26Mg and 40Ca at E(9Be) = 43 and 45 MeV, respectively (1985WI18) and on 26Mg, 27Al and 40Ca at E(9Be) = 158.1 - 158.3 MeV (1984FU10). For pion production in reaction (a) see (1985FR13). The interaction cross section for 790 MeV/A 9Be on 27Al has been measured by (1985TA18). Breakup measurements involving 40Ca are reported by (1984GR20). See also the other references cited in (1988AJ01).

33. 10Be(d, t)9Be Qm = -0.5550

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).

34. 10B(γ, p)9Be Qm = -6.5859

Angular distributions have been measured for protons leading to a number of excited states of 9Be using tagged photons of mean energies Eγ = 57.6 and 72.9 MeV. The spectrum of states excited is very similar to that from the 10B(e, e'p)9Be and proton pickup reactions from 10B. However, the spectroscopic information is limited in that direct knockout calculations account for only part of the cross sections and meson-exchange current contributions are found to be large (1998DE34).

35. 10B(e, e'p)9Be Qm = -6.5859

Measurements have been performed in parallel kinematics at incident energies of 407.3 and 498.1 MeV such that Ecm = 70 or 120 MeV for the outgoing proton. The momentum distributions for energy bins centered around the strong peaks in the spectrum are characteristic of p-shell knockout (1998DE23). The measured excitation energies and relative spectroscopic factors are shown in Table 9.12 preview 9.12 (in PDF or PS) (1993DE2A). In absolute terms, 54 ± 2% of the individual-particle shell-model sum rule for 0p strength is accounted for up to Ex = 19 MeV.

36. 10B(n, d)9Be Qm = -4.3613

See (1974AJ01).

37. 10B(p, 2p)9Be Qm = -6.5859

This reaction shows several peaks corresponding to proton removal from the p shell and the inner s shell. See (1974AJ01) and (1985BE30, 1985DO16).

38. 10B(d, 3He)9Be Qm = -1.0924

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 with S = 0.72 and 0.82 for 9Be*(0, 2.4): see (1979AJ01). At Ed = 52 MeV, S = 1.20, 1.23, and 0.70 for the 0, 2.43, and 6.66 MeV levels; 9Be*(11.3) appears to be strongly populated but is masked by strong transitions from target contaminants (1975SC41). An analysis for Ed = 11.8 MeV and a study of the uniqueness of the asymptotic normalization coefficient method is discussed in (2000FE08).

39. 10B(t, α)9Be Qm = 13.2280

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). See also (1984AJ01) and (1982CI1A).

40. 10B(7Be, 8B)9Be Qm = -6.4484

This reaction was studied with an 84 MeV 7Be radioactive beam (1999AZ02, 2001GA19, 2001TR04). The measured cross section determined the asymptotic normalization coefficients for the virtual transition 8B → 7Be + p which may be used to calculate the astrophysical S factor for (7Be(p, γ)8B at solar energies. See also the calculations and analysis of (1995GA20).

41. 11B(p, 3He)9Be Qm = -10.322

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). 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 = 14392.2 ± 1.8 keV (1974KA15), using Qm. Cross sections for this reaction at Ep = 4 - 11 MeV were calculated by (1994SH21) with Feshbach-Kerman-Koonin quantum multi-step direct reaction theory.

42. (a) 11B(d, α)9Be Qm = 8.031
(b) 11B(d, nα)4He4He Qm = 6.458

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] is Γcm = 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: Γcm = 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 [see Table 9.3 preview 9.3 (in PDF or PS): 0.091 ± 0.010 eV], Γ = 0.78 ± 0.13 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)]. Recent measurements for Ecm = 57 - 141 keV were reported by (1997YA02, 1997YA08). Astrophysical S-factors were deduced. 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) state is to 5Heg.s. + α while 9Be*(3.1, 4.7) states decay to 8Beg.s. + n. It should be noted, however, that the peaks corresponding to 9Be*(3.0) have a FWHM of ≈ 1 MeV, which may imply that 9Be*(2.8) is involved.

43. 12C(γ, pd)9Be Qm = -31.7723

See (1986BU22, 1987BU1A, 1987VO08, 1988BU06). More recently, the reaction was studied at Eγ = 150 - 400 MeV with tagged photons (1999MC06).

44. (a) 12C(n, α)9Be Qm = -5.7012
(b) 12C(n, nα)4He4He Qm = -7.274747

Angular distributions of the α0 group have been measured at En = 13.9 to 18.8 MeV [see (1974AJ01)] and at 14.1 MeV (1984HA48). 9Be*(1.7, 2.4, 3.1, 6.8) are also populated. Cross sections and particle-spectra related to neutron detector development have been measured at En = 4 - 11 MeV (1991BR09), 14.1 MeV (2000SA06), 14.6 MeV (1994KO53) and 40, 56 MeV (1994MO41). See also the calculated cross sections of (1989BR05). Reaction (b) at En = 13 to 18 MeV involves 9Be*(2.4). See (1984HA48) for differential cross sections at 14.1 MeV and for partial and total cross sections.

45. 12C(p, p3He)9Be Qm = -26.2788

See (1985DE17; Ep = 58 MeV), and the calculations of (1987ZH10; Ep ≈ 0.7 GeV).

46. 12C(t, 6Li)9Be Qm = -10.4846

Differential cross sections were measured at Et = 33 MeV to 9Beg.s. (1989SI02). Spectroscopic factors for 3He-cluster pickup were deduced.

47. 12C(α, 7Be)9Be Qm = -24.6927

Cross section measurements at Eα = 90 MeV and DWBA analysis are reported in (1991GL03). See also 7Be in (2002TI10).

48. (a) 12C(7Li, 10B)9Be Qm = -8.4905
(b) 12C(12C, 15O)9Be Qm = -14.203
(c) 12C(13C, 16O)9Be Qm = -3.4856
(d) 12C(14N, 17F)9Be Qm = -10.4359

For reaction (a) see 10B. Differential cross sections for reaction (b) were measured at E(12C) = 480 MeV (1988KR11). For reaction (c) see (1988KR11) and (1985OS06). For reaction (d) see (1986GO1B; E(14N) = 150 MeV).

49. 13C(t, 7Li)9Be Qm = -8.1806

Differential cross sections were measured at Et = 33 MeV to 9Be*(0, 2.43) (1989SI02). Spectroscopic factors for α-cluster pickup were deduced.

50. 13C(3He, 7Be)9Be Qm = -9.0614

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: see (1979AJ01).

51. 13C(α, 8Be)9Be Qm = -10.7393

See 8Be here and 9Be in (1979AJ01).

52. 14N(7Li, 12C)9Be Qm = 6.4236

See (1986GO1B; E(14N) = 150 MeV).

53. 16O(α, 11C)9Be Qm = -24.3100

See (1987KW01, 1987KW02).

54. 16O(13C, 20Ne)9Be Qm = -5.9177

See 20Ne in (1987AJ02). See also (1985KA1J).