
^{9}Be (2004TI06)(See Energy Level Diagrams for ^{9}Be) GENERAL: References to articles on general properties of ^{9}Be published since the previous review (1988AJ01) are grouped into categories and listed, along with brief descriptions of each item, in the General Tables for ^{9}Be located on our website at (nucldata.tunl.duke.edu/nucldata/General_Tables/9be.shtml). See also 2 in (1988AJ01) [Electromagnetic Transitions in A = 510] (in PDF or PS), 9.2 [Table of Energy Levels] (in PDF or PS) and 9.3 [Electromagnetic transitions in ^{9}Be] (in PDF or PS).
Interaction cross sections of ^{9}Be with Be, C, and Al targets have been measured at E = 790 MeV/A yielding an interaction nuclear radius of ^{9}Be 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 ^{9}Be. The decay ^{9}Li_{Λ} → π^{} + ^{9}Be* → π^{} + p + ^{8}Li appears to take place via a T = 3/2 state of ^{9}Be at E_{x} = 18.6 ± 0.1 MeV (Γ ≤ 300 keV) that appears to be an analog of the 4.3 MeV level of ^{9}Li (1985PN01). For a discussion of the structure and widths of levels in ^{9}Be and ^{9}B, see the general discussion of ^{9}B.
The 0° differential cross section for reaction (a) increases monotonically between E_{t} = 0.10 and 2.4 MeV. A resonance has been reported at E_{t} = 1.875 MeV (^{9}Be*(18.94)). The excitation function for ^{8}Li (reaction (b)) increases monotonically for E_{t} = 0.275 to 1.000 MeV. See (1974AJ01) for references. In the range E_{t} = 2 to 10 MeV the total cross section for reaction (b) shows a broad structure [Γ_{cm} = 1.5 MeV] at E_{t} = 4.2 MeV (^{9}Be*(20.5)) (1986AB04). Yields and angular distributions for reaction (c) have been measured at E_{t} = 2 to 4.5 MeV (1984LIZY). See also (1984AJ01) for other channels and (1984KR1B).
The energy dependence of the cross section for population of ^{9}Be_{g.s.} has been measured at E(^{3}He) = 235 to 283 MeV (1984WI06).
Angular distributions of p_{0} have been measured at E_{α} = 10.2 to 14.7 MeV and at 30 MeV: see (1974AJ01). Differential cross sections were measured at E_{α} = 26.7 MeV (1990LI37) in a study of exchange processes. See also (1987BI1C) and (1983BE51).
For E_{d} = 0.1 to 1.1 MeV, a resonance in the yield of capture γrays is observed at E_{d} = 360.8 ± 0.3 keV (1987ZI01), 360.7 ± 1.8 keV (1986BE33), corresponding to the excitation of ^{9}Be*(16.97), the second T = 3/2 state [J^{π} = 1/2^{}]: see 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 E_{d} = 6 MeV.
The yield of neutrons has been measured for E_{d} = 0.2 to 23 MeV [see (1979AJ01)] and at E_{d} = 0.19 to 0.55 MeV (1987DA25). See also (1983SZZY). Polarization measurements have been carried out at E_{d} = 0.64 MeV and 2.5 to 3.7 MeV [see (1974AJ01)] and at 0.40 and 0.46 MeV (1984GA07; n_{0}). Resonances are reported at 0.36, 0.68 and 0.98 MeV: see 9.3 (in PDF or PS) in (1974AJ01). See also (1985CA41; astrophys.) and the measurements at E_{d} = 195  550 keV of (1987DA25). Neutron yields for 40 MeV deuterons on ^{7}Li thick targets were measured by (1987SC11). See also the measurements at E_{cm} = 0.7  2.3 MeV (1996BO27) and the fusion calculations of (2000HA50). The yields of αparticles have been measured for E_{d} = 0.25 to 3.0 MeV: see (1974AJ01, 1979AJ01). Resonances are reported at E_{d} = 0.75, 1.00 and 2.5 MeV; the latter is broad: see 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 E_{cm} = 57  141 keV have been reported by (1997YA08). See also the calculations described in (2000HA50).
Excitation functions and cross sections have been measured for E_{d} = 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 [Γ_{lab} in brackets in keV] of resonances reported are: E_{d} = 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 ^{9}Be*(16.975) [see also 9.5 (in PDF or PS)], 17.298, 17.493, (18.5), 18.54, 19.20, 20.4): for references see 9.3 (in PDF or PS) in 1979AJ01, and 9.3 (in PDF or PS) in 1984AJ01. The total cross section at the E_{d} = 0.78 MeV resonance is important because it serves as a normalization for the ^{7}Be(p, γ)^{8}B reaction: the "best" value suggested by (1983FI13) is 157 ± 10 mb. See also (1986BA38) and (1974AJ01, 1984AJ01) for the earlier values. At E(^{7}Li) = 12.2 ± 1.3 MeV [corresponding to E_{d} = 3.5 MeV] the cross section is reported to be 155 ± 20 mb (1985HA40). At the peak of the E_{d} = 0.78 MeV resonance, σ = 143.6 ± 8.9 mb from the proton yield and σ = 151 ± 20 mb from the βdelayed α activity of the residual ^{8}Li nucleus (1996ST18). In (1998WE05), a value σ = 155 ± 8 mb was obtained, backscattering effects were examined, and the consequences for the ^{7}Be(p, γ) cross sections were discussed. The ^{7}Li(d, p) yield for E_{d} = 0.4  1.8 MeV was measured by (1998ST20) to deduce corrections due to recoil loss. See also the compilation and analysis of astrophysical Sfactor data and calculations in (1998AD12).
The elastic scattering [E_{d} = 0.4 to 1.8 MeV] shows a marked increase in cross section for E_{d} = 0.8 to 1.0 MeV (perhaps related to ^{9}Be*(17.30)) and a conspicuous anomaly at E_{d} = 1.0 MeV, due to pwave deuterons [^{9}Be*(17.50)]. The elastic scattering has also been studied for E_{d} = 1.0 to 2.6 MeV and 10.0 to 12.0 MeV: see (1979AJ01), and at E_{d} = 9.05 MeV (1980YE02).
The cross section rises steeply from threshold to 95 mb at E_{d} = 2.4 MeV and then more slowly to ≈ 165 mb at E_{d} = 4.1 MeV. The t_{0} yield curve (θ_{lab} = 155°) decreases monotonically for E_{d} = 10.0 to 12.0 MeV: see (1974AJ01). Differential cross sections measured at E_{d} = 30.7 MeV were reported in (1987BO39). An analysis of data from this reaction at E_{d} = 8  50 MeV is discussed in (1995GU22).
Observed proton groups are displayed in 9.6 (in PDF or PS). The parameters for the particle and γdecay of observed states are displayed in 9.4 (in PDF or PS) and 9.7 (in PDF or PS). Angular distributions have been reported in the range E(^{3}He) = 0.9 to 14 MeV [see (1974AJ01, 1979AJ01)] and at E(pol. ^{3}He) = 14 and 33 MeV (1983LE17, 1983RO22; p_{0}). See also ^{10}B, (1984ME11) and (1986SC35; applications). In more recent work cross sections σ(E_{p}, θ) were measured at E_{cm} = 0.5  2 MeV, and the astrophysical Sfactor was deduced (1990RA16). Polarization observables were measured at E(^{3}He) = 4.6 MeV and analyzed by DWBA (1995BA24). See (1993YA01) for Sfactor calculations and discussions of astrophysical implications. See also the earlier theoretical work of (1988KH11) on timereversal violating amplitude features.
Angular distributions of d_{0}, d_{1} and d_{2} have been reported at E_{α} = 30 MeV: see (1974AJ01). See also (1983BE51).
Angular distributions of the αgroups to ^{9}Be*(0, 2.43, 6.76) have been measured at E(^{7}Li) = 78 MeV (1989GL03). For the excitation of ^{4}He* see (1987GLZX, 1987GLZY; E(^{6}Li) = 93 MeV). For the earlier work see (1974AJ01).
^{9}Li decays by β^{} emission with τ_{1/2} = 178.3 ± 0.4 msec and P_{n} = 50.8 ± 0.9% to several ^{9}Be states: see reaction 1 in ^{9}Li and 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 ^{9}Be*(11.28) and/or ^{9}Be*(11.81). The information in 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 lowenergy decays are mostly to ^{9}Be*(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 ^{9}C (see reaction 10 in ^{9}B). Such a large asymmetry for a strong transition and the magnitude of the B(GT) value for ^{9}Li 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 sumrule strength 9(g_{A}/g_{V})^{2}_{ eff} [see footnote ^{c} in 9.8 (in PDF or PS)] goes to 5/2^{} states.
As noted in the previous review (1988AJ01), "the photoneutron cross section has been measured from threshold to 320 MeV: see 9.6 (in PDF or PS) in (1966LA04), (1979AJ01) and (1988DI02). A pronounced peak occurs ≈ 29 keV above threshold with σ_{max} = 1.33 ± 0.24 mb. The shape of the resonance has been measured very accurately for E_{γ} = 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 E_{x} = 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 E_{x} = 1.68 MeV (1/2^{+}), 2.43 MeV (5/2^{}), and 3.05 MeV (5/2^{+}) in ^{9}Be. See Table 1 in (1992GO27) for resonance parameters. In other work (2001UT01, 2002SU19), laserinduced Compton backscattering photons with E_{γ} = 1.78  6.11 MeV were used to measure the photoneutron cross section resonance parameters for the ^{9}Be 1/2^{+}, 5/2^{} and 5/2^{+} states; see 9.9 (in PDF or PS). The radiative widths in 9.9 (in PDF or PS) are not in good agreement with those from lowenergy electron scattering listed in 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 9.2 (in PDF or PS); using the accepted width while maintaining a fit to the peak (γ, n) cross section would reduce Γ_{γ} by almost a factor of two and into the range of the values from (e, e') listed in 9.3 (in PDF or PS). Shellmodel calculations give a stable B(M1)(↓) ≈ 1 W.u. (Γ_{γ} ≈ 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 onelevel Rmatrix analysis of the E_{γ} = 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 Γ_{γ}'s than those listed in 9.3 (in PDF or PS) and 9.9 (in PDF or PS). For theoretical calculations of the lowenergy (γ, n) cross section see (1998EF05, 1999EF01, 2002IT07). See also the calculation of ^{9}Be 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 E_{γ} = 17 to 37 MeV with weak structures which correspond to E_{x} = 17.1, 18.8, 19.9, 21.4, 22.4, 23.8 [± 0.2] MeV and 27 ± 0.5 MeV (broad). In the range E_{γ} = 18 to 26 MeV the integrated (γ, n_{0}) cross section is < 0.1 MeV · mb, that for (γ, n_{1}) = 2.4 ± 0.4 MeV · mb and the combined integrated cross section for (γ, n) to ^{8}Be*(16.6) and (γ, α_{0}) to ^{5}He_{g.s.} is 13.1 ± 2 MeV · mb". "The total absorption cross section has been measured for E_{γ} = 10 to 210 MeV: it rises to ≈ 5 mb at ≈ 21 MeV, decreases to about 0 at 160 MeV and then increases to ≈ 1.5 mb at 210 MeV. An integrated cross section of 156 ± 15 MeV · mb is reported for E_{γ} = 10 to 29 MeV as is resonant structure at E_{γ} = 11.8, (13.5), 14.8, (17.3), (19.5), 21.0, (23.0), and (25.0) MeV. Fine structure is also reported at E_{γ} = 20.47 ± 0.04 and 20.73 ± 0.04 MeV. See (1979AJ01) for references. At E_{γ} = 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 E_{e} = 100 to 225 MeV see (1986LI22). For hadron production at high energies see (1983AR24)". See also the earlier work cited in (1988AJ01).
The yield shows structure in the energy region corresponding to the ^{9}Be levels at 17  19 MeV followed by the giant resonance at E_{γ} ≈ 23 MeV (σ = 2.64 ± 0.30 mb). Structure attributed to eleven states of ^{9}Be with 18.2 < E_{x} < 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 ^{8}Li*(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 E_{γ} = 360  600 MeV, see (1984BA09). See also (1984AJ01) and (1984HO24), and see the analysis for E_{γ} = 200  420 MeV by (1988TE04). The integrated cross sections are reported to be 1.0 ± 0.5 MeV · mb (E_{γ} = 21  33 MeV) for reaction (c) to ^{7}Li*(0 + 0.4), and 0.6 ± 0.3 MeV · mb (E_{γ} = 25  33 MeV) for reaction (d) to ^{6}Li_{g.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 E_{γ} = 247 MeV are presented in (1993BO35). 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, have been reported: see (1974AJ01). A recent measurement and clustermodel analyses for reactions (a), (c), (d) for E_{γ} = 21  39 MeV are described in (1999SH05). For momentum spectra of deuterons and tritons at E_{γ} = 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, π^{0})]. For a high energy study of hadron production see (1983AR24). See also (1986MC1G), (1985HO27, 1985MA1G) and the calculations of (1983TR04, 1986HO11, 1987LU1B, 1988DU04).
The ground state radiative widths of the E_{x} = 14.393 and 16.975 MeV T = 3/2 levels of ^{9}Be have been measured in a resonant absorption experiment (1992KI05) that updates the results of (1986ZI01, 1987ZI01). The results are Γ_{γ0} = 5.9 ± 0.8 eV and Γ_{γ0} = 16.9 ± 1.0 eV for E_{x} = 14.393 and 16.975 MeV, respectively. See 9.4 (in PDF or PS) and 9.5 (in PDF or PS). With E_{brem} = 31 MeV eight resonances in (γ, γ') were reported for 17.4 < E_{x} < 29.4 MeV (1984AL22).
Q = 5.86 ± 0.06 fm^{2} (1991GL02); b = 1.5_{0.2}^{+0.3} fm (1973BE19, 1979AJ01) [b = oscillator parameter]; < r^{2} >^{1/2}_{M} = 3.2 ± 0.3 fm; Ω = 6 ± 2 μ_{N} · fm^{2} [this value of the magnetic octupole moment implies a deformation of the average nuclear potential] (1975LA23, 1979AJ01). The previous review (1988AJ01) observed that: "The elastic scattering of electrons has been studied for E_{e} up to 700 MeV. Magnetic elastic scattering gives indications of both M1 and M3 contributions. Inelastic scattering populates a number of levels: see 9.8 (in PDF or PS) in (1988AJ01). At E_{e} = 45 and 49 MeV ^{9}Be*(1.68) has a strongly asymmetric line shape, as expected from its closeness to the ^{8}Be + n threshold. The form factor is dominated by a 0p_{3/2} → 1s_{1/2} particlehole transition. ^{9}Be*(2.43) is strongly excited (1987KU05). Form factors have also been measured for ^{9}Be*(0, 14.39, 16.67, 16.98, 17.49) by (1983LO11; E_{e} = 100.0 to 270.2 MeV). See also (1985HY1A, 1986MA48, 1987HY01). (1984WO09) suggests that the T = 1/2 states [^{9}Be*(16.67, 17.49)] have J^{π} = 5/2^{+} and 7/2^{+}, respectively, and that they have large parentage amplitudes with ^{8}Be*(16.6 + 16.9) [J^{π} = 2^{+}], rather than with ^{8}Be_{g.s.}. See (1974AJ01, 1979AJ01, 1984AJ01). In a more recent study (1991GL02), electrons at energies between 110 and 360 MeV were used along with detailed lineshape analysis to extract cross sections for states at E_{x} = 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 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 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 Δresonance regions see references cited in (1988AJ01).
The elastic scattering, and inelastic scattering to ^{9}Be*(2.43, 6.76) have been studied at E_{π±} = 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 ^{9}Be located on our website at (nucldata.tunl.duke.edu/nucldata/General_Tables/9be.shtml). Calculations of threshold pionnucleus amplitude by current algebra are discussed in (1989GE10). See also the diffraction theory calculations of the scattering process by (2000ZH50).
The population of ^{9}Be*(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 9.7 (in PDF or PS). Angular distributions have been measured at E_{n} = 3.5 to 14.93 MeV [see (1974AJ01, 1979AJ01, 1984AJ01)], at E_{n} = 7 to 15 MeV (1983DA22; n_{0}), 11 to 17 MeV (1985TE01; n_{0}, n_{2}), 14.6 MeV (1985HA02, 1986HAYU; n_{0}) and 14.7 MeV (1984SH01; n_{0}, n_{2}) as well as at E_{n} = 9 to 17 MeV (1984BY03; n_{0}, n_{2}; see also for transition to ^{9}Be*(6.76)). See also ^{10}Be, and other early work cited in (1988AJ01). Spindependent scattering lengths were measured at low energies (1987GL06) by a pseudomagnetic precession method, and cross sections were measured at E_{n} = 1  10 MeV (1989SU13) and E_{n} = 21.6 MeV (1990OL01). Calculations and analysis for ^{9}Be(n, n) are reported in (1988FE06, 1991IO01, 1996CH33, 2001BO10). For reaction (b) the n  n scattering length was measured at E_{n} = 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 ^{9}Be(n, 2n) at E_{n} = 5.9 MeV (1988BE04).
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 E_{p} = 2.3 to 1000 MeV [see (1974AJ01, 1979AJ01, 1984AJ01)], at E_{p} = 2.31 to 2.73 MeV (1983AL10; p_{0}), 11 to 17 MeV (1988AJ01; p_{0}) and 1 GeV (1985AL16; p_{0}) as well as at E_{pol. p} = 200 MeV (1985GLZZ; p_{0}) and 220 MeV (1985RO15; p_{0}, p_{2}). The elastic distributions show pronounced diffraction maxima. A quadrupoledeformed opticalmodel potential is necessary to obtain a good fit to the p_{0} and p_{2} angular distributions: see (1974AJ01). The spinflip probability at E_{pol. p} = 31 MeV is ≈ 0 for the p_{2} group, which is expected in view of the collective nature of the transition (1981CO08)." "The structure corresponding to ^{9}Be*(1.7) is asymmetric, as expected: see reaction 16 and 9.8 (in PDF or PS) in (1988AJ01) for its parameters. [At E_{p} = 13 MeV the spectra are dominated by ^{9}Be*(2.43) (1987KU05)]. The weighted mean of the values of E_{x} for ^{9}Be*(2.4) listed in (1974AJ01) is 2432 ± 3 keV. ^{9}Be*(3.1) has E_{x} = 3.03 ± 0.03 MeV, Γ = 250 ± 50 keV, J^{π} = (3/2^{+}, 5/2^{+}). Higher states are observed at (E_{x} and Γ in MeV) 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], 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 ^{9}Be*(2.4, 6.8) is consistent with the assumption that they have J^{π} = 5/2^{} and 7/2^{}, respectively, and are members of the ground state K = 3/2^{} band. See (1966LA04, 1974AJ01) for references." In an experimental and theoretical study of ^{9}Be structure (1991DI03), cross section and analyzing power measurements made with 180 MeV protons provided data for 24 states below E_{x} = 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^{+} weakcoupling state at 6.76 MeV. Level energies, suggested assignments and widths are summarized in 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 E_{p} = 135 MeV (1988KE04, 1989KE03), and at E_{p} = 54.7 and 74.7 MeV (1994DE23). The data from these experiments were analyzed with other data for 30 < E_{p} < 220 MeV in terms of a variety of optical model and coupledchannel analyses to calculate finalstate interaction effects for proton knockout reactions on ^{10}B (1994DE23). Microscopic coupledchannel calculations for the groundstate rotational band of ^{9}Be and 100 < E_{p} < 500 MeV have been made using the folding model and densitydependent interactions (1992KE05). Elastic scattering cross sections have been reported at E_{p} ≤ 2.66 MeV (1994WR01), and applicationrelated scattering cross sections at E_{p} = 2.3  2.7 keV (1988LA07) and E_{p} = 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); GlauberSitenko theory calculations for E_{p} = 0.22, 1 GeV (1996ZH31); microscopicmodel analysis for E_{p} = 200 MeV (1997DO01); Glaubermodel calculations for E_{p} = 0.22, 1.0 GeV (1997ZH39); calculations of polarization features for E_{p} = 0.22, 1.0 GeV (1998ZH02); and diffraction theory calculations for E_{p} = 0.16  1.04 GeV (2000ZH50).
The reactions (p, 2p)X and (p, pd)X have been studied at E_{p} = 300 MeV (1983GR21, 1984HE03). For reactions (a) and (c) see also ^{8}Li, ^{8}Be (1985BE30, 1985DO16; 1 GeV) and (1984AJ01). Reaction (c) at E_{p} = 10  24 MeV involves ^{9}Be*(3.0, 4.7): see (1984AJ01). See also (1984WA21). For reactions (b) and (d) at E_{p} = 58 MeV see ^{7}Li and ^{6}Li in (2002TI10), and (1984DE1F, 1985DE17). For reactions (e) and (f) see (1985PAZL; E_{pol. p} = 70 MeV). The (p, pα) process (reaction (f)) has been studied at E_{p} = 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 ^{4,6,8}He and ^{6,7,8}Li formation by 1 GeV protons on ^{9}Be were measured by (1994AM09). Cross section and proton and neutron spectra for reactions (a) and (c) at E_{p} = 70 MeV were studied by (2000SH01). See also the earlier work cited in (1988AJ01).
Angular distributions have been measured in the range 1.0 to 410 MeV [see (1974AJ01, 1979AJ01, 1984AJ01)] and at E_{d} = 2.0 to 2.8 MeV (1983DE50, 1984AN16). See also ^{11}B in (1990AJ01). Inelastic groups have been reported to ^{9}Be*(1.7, 4.7, 6.8) and to states with E_{x} = 2431.9 ± 7.0 keV and 3040 ± 15 keV (Γ = 294 ± 20 keV): see (1974AJ01). Measurements at E_{d} = 6.7  7.5 MeV of differential cross sections for inelastic groups to ^{9}Be*(2.43) and DWBA analysis were reported by (1989SZ02). An analysis by (1989VA17) of (d, d') data at E_{d} = 13.6 MeV found evidence for kinematic focusing of the products of 3particle decay of ^{9}Be*(2.43). An opticalmodel description for E_{d} = 4  11 MeV is discussed in (1993AB10).
Angular distributions of elastically scattered tritons have been measured at E_{t} = 2.10 MeV and at E_{pol. t} = 15 and 17 MeV: see (1974AJ01, 1984AJ01). A more recent analysis by a strong absorption model of cross sections measured at E_{t} = 17 MeV is reported in (1994SO26). Reaction (b) at 4.2 and 4.6 MeV proceeds via ^{9}Be*(2.4): see (1974AJ01).
Angular distributions have been studied for E(^{3}He) = 1.6 to 46.1 MeV and at 217 MeV [see (1974AJ01, 1979AJ01, 1984AJ01)]. At E(^{3}He) = 39.8 MeV, ^{9}Be*(1.7, 2.4, 3.1, 4.7, 6.8, 14.4) are populated. Data for E(^{3}He) = 50, 60 MeV were analyzed by (1992AD06), and rainbow effects were observed. Differential cross sections for E(^{3}He) = 60 MeV were measured by (1993MA48, 1996RU13). Measurements and analysis of the αparticle spectra from the decay of ^{9}Be*(2.43) populated in the inelastic scattering reaction with E(^{3}He) = 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(^{3}He) = 3 to 12 MeV (1986LA26) and 11.9 to 24.0 MeV (1987WA25). See also (1990BO51). For the earlier work see (1984AJ01).
Angular distributions have been studied at many energies in the range E_{α} = 5.0 to 104 MeV [see (1974AJ01, 1984AJ01)] and E_{α} = 23.1 MeV (1984HU1D, 1985HU1B; α_{0}, α_{2}). At E_{α} = 35.5 MeV, states belonging to the K = 3/2^{} groundstate band are strongly excited [^{9}Be*(0, 2.43, 6.76, 11.28); it is suggested that the latter has J^{π} = (9/2^{}); see, however, reaction 12]. The first three states belonging to the K = 1/2^{+} band are also excited [^{9}Be*(1.68, 3.05, 4.70)] (1982PE03; coupled channels analysis). A coupled channel folding model analysis for data at E_{α} = 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 applicationrelated work backscattering cross sections were measured for E_{α} = 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); S_{α} = 0.96 [see (1984AJ01)] and (1987WA25; E(^{3}He) =12 to 24 MeV). A measurement of energysharing distributions at E_{α} = 197 MeV was reported in (1994CO16). Cluster knockout at E_{α} = 580 MeV was studied by (1999NA05). See also ^{8}Be, (1987BU27, 1987KO1K) and (1984LI28, 1985SR01).
The cross section at E(^{6}He) = 8.8  9.3 MeV was measured by (1991BE49).
Elastic angular distributions have been measured at E(^{6}Li) = 4, 6 and 24 MeV and at E(^{7}Li) = 24 and 34 MeV [see (1979AJ01)] as well as at E(^{6}Li) = 32 MeV (1985CO09; also to ^{9}Be*(2.43)) and 50 MeV (1988TRZY) and E(^{7}Li) = 78 MeV (1986GLZV, 1986GLZU; also to ^{9}Be*(2.43, 6.76)). More recently, measurements and analysis of complete angular distributions for elastic scattering and inelastic scattering to ^{9}Be*(2.43) at E_{cm} = 7, 10, 12 MeV were reported by (1995MU01). See also the cross section measurements and optical model analysis for E(^{6}Li) = 50 MeV (1990TR02) and the analyzing power measurements for elastic and inelastic scattering at E(^{6}Li) = 32 MeV (1993RE08). Thresholds of nonRutherford cross sections for ionbeam analysis were studied by (1991BO48). For the interaction cross section at E(^{6}Li) = 790 MeV/A see (1985TA18). For reaction (b), cross section measurements at E(^{7}Li) = 63, 130 MeV and opticalmodel analyses are reported in (2000TR01). The α  ^{5}He decay of ^{9}Be excited states populated by E(^{7}Li) = 52 MeV was studied by (1998SO05).
Elastic angular distributions have been obtained at E(^{9}Be) = 5 to 26 MeV [see (1979AJ01, 1984AJ01)] and at 35 to 50 MeV (1984OM02; also to ^{9}Be*(2.43)). See also (1985JA09). For yields and cross sections see (1984OM03, 1986CU02, 1988LA25). See also the applicationrelated measurement at E(^{9}Be) = 5.5 MeV (1988DA05). In more recent work, elastic scattering measurements at E(^{9}Be) = 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(^{9}Be) = 790 MeV/A see (1985TA18).
Elastic angular distributions have been reported at E(^{10}B) = 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(^{10}B) = 100 MeV (1997MU19, 2000TR01). Optical model parameters and values of the asymptotic normalization coefficients (ANC) for ^{10}B → ^{9}Be + p were deduced.
Elastic angular distributions have been measured for reaction (a) at E(^{12}C) = 12, 15, 18 and 21 MeV and E(^{9}Be) = 14 to 76.6 MeV [see (1979AJ01, 1984AJ01)] and 158.3 MeV (1984FU10) as well as at E(^{12}C) = 65 MeV (1985GO1H; various ^{12}C states). For yield and fusion crosssection measurements see (1983JA09, 1985DE22) and (1984AJ01). Angular distributions and excitations functions for elastic scattering and inelastic scattering to ^{9}Be*(2.43) for E_{cm} = 10.9 MeV are reported in (1995CA26). Reorientation and coupling effects in the ^{9}Be + ^{12}C system were studied. See also the measurements and analysis for E_{cm} = 5.14  90.46 MeV of (2000RU02). Elastic angular distributions for reaction (b) are reported for E(^{9}Be) = 14 to 26 MeV: see (1984AJ01). Measurements and opticalmodel analysis for E(^{13}C) = 130 MeV are reported in (2000TR01). For yield measurements see (1984DA17, 1986CU02). See also the earlier work cited in (1988AJ01).
Elastic angular distributions have been measured at E(^{14}N) = 25 and 27.3 MeV: see (1974AJ01). For a fusion study see (1984MA28).
Elastic angular distributions have been reported in the range E(^{16}O) = 15 to 30 MeV [see (1979AJ01)] and (1988WE17), at E(^{9}Be) = 14, 20 and 26 MeV [see (1984AJ01)], 43 MeV (1985WI18) and 157.7 MeV (1984FU10), as well as at E(^{18}O) = 12.1, 16 and 20 MeV [see (1974AJ01)]. See also the other references cited in (1988AJ01).
Elastic angular distributions have been measured for many of these reactions: see (1979AJ01, 1984AJ01). They have been studied on ^{26}Mg and ^{40}Ca at E(^{9}Be) = 43 and 45 MeV, respectively (1985WI18) and on ^{26}Mg, ^{27}Al and ^{40}Ca at E(^{9}Be) = 158.1  158.3 MeV (1984FU10). For pion production in reaction (a) see (1985FR13). The interaction cross section for 790 MeV/A ^{9}Be on ^{27}Al has been measured by (1985TA18). Breakup measurements involving ^{40}Ca are reported by (1984GR20). See also the other references cited in (1988AJ01).
Forward angular distributions have been obtained at E_{d} = 15.0 MeV for the tritons to ^{9}Be*(0, 1.7, 2.4, 3.1). The groundstate transition is well fitted by l = 1. The transition to ^{9}Be*(1.7) [≈ 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).
Angular distributions have been measured for protons leading to a number of excited states of ^{9}Be using tagged photons of mean energies E_{γ} = 57.6 and 72.9 MeV. The spectrum of states excited is very similar to that from the ^{10}B(e, e'p)^{9}Be and proton pickup reactions from ^{10}B. However, the spectroscopic information is limited in that direct knockout calculations account for only part of the cross sections and mesonexchange current contributions are found to be large (1998DE34).
Measurements have been performed in parallel kinematics at incident energies of 407.3 and 498.1 MeV such that E_{cm} = 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 pshell knockout (1998DE23). The measured excitation energies and relative spectroscopic factors are shown in 9.12 (in PDF or PS) (1993DE2A). In absolute terms, 54 ± 2% of the individualparticle shellmodel sum rule for 0p strength is accounted for up to E_{x} = 19 MeV.
See (1974AJ01).
This reaction shows several peaks corresponding to proton removal from the p shell and the inner s shell. See (1974AJ01) and (1985BE30, 1985DO16).
Angular distributions of the ^{3}He groups corresponding to ^{9}Be*(0, 2.4) have been studied at E_{d} = 11.8, 28 and 52 MeV [the latter also to ^{9}Be*(6.7)], and at E_{d} = 15 MeV with S = 0.72 and 0.82 for ^{9}Be*(0, 2.4): see (1979AJ01). At E_{d} = 52 MeV, S = 1.20, 1.23, and 0.70 for the 0, 2.43, and 6.66 MeV levels; ^{9}Be*(11.3) appears to be strongly populated but is masked by strong transitions from target contaminants (1975SC41). An analysis for E_{d} = 11.8 MeV and a study of the uniqueness of the asymptotic normalization coefficient method is discussed in (2000FE08).
At E_{t} = 12.9 MeV αgroups are observed to the ground state of ^{9}Be and to excited states at E_{x} = 1.75 ± 0.03, 2.43, 3.02 ± 0.04 (Γ = 320 ± 60 keV), 11.27 ± 0.04 (Γ = 530 ± 70 keV), (14.4) [Γ ≈ 800 keV], 14.39 and 16.67 MeV. The T = 3/2 state ^{9}Be*(14.39) is very weakly populated [≈ 5% of intensity of α_{2}]. The angular distribution of the α_{2} group shows sharp forward and backward peaking. The α_{0} group is not peaked in the backward direction: see (1979AJ01). See also (1984AJ01) and (1982CI1A).
This reaction was studied with an 84 MeV ^{7}Be radioactive beam (1999AZ02, 2001GA19, 2001TR04). The measured cross section determined the asymptotic normalization coefficients for the virtual transition ^{8}B → ^{7}Be + p which may be used to calculate the astrophysical S factor for (^{7}Be(p, γ)^{8}B at solar energies. See also the calculations and analysis of (1995GA20).
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). Angular distributions are also reported at E_{p} = 40 MeV. The intensity of the group to ^{9}Be*(3.1) is ≈ 1% of the groundstate group at that energy: see (1974AJ01). The excitation energy of the first T = 3/2 state is E_{x} = 14392.2 ± 1.8 keV (1974KA15), using Q_{m}. Cross sections for this reaction at E_{p} = 4  11 MeV were calculated by (1994SH21) with FeshbachKermanKoonin quantum multistep direct reaction theory.
Alpha groups are reported corresponding to ^{9}Be*(0, 1.7, 2.4, 3.1). The width of ^{9}Be*(1.7) [E_{x} = 1.70 ± 0.01 MeV] is Γ_{cm} = 220 ± 20 keV. The weighted mean of the values of E_{x} of ^{9}Be*(2.4), reported in (1974AJ01), is 2425 ± 3 keV. The 5/2^{+} state is at E_{x} = 3.035 ± 0.025 MeV: Γ_{cm} = 257 ± 25 keV. The ratio Γ_{γ}/Γ of ^{9}Be*(1.7) ≤ 2.4 × 10^{5}, that for ^{9}Be*(2.4) is reported to be (1.16 ± 0.14) × 10^{4}. Since Γ_{γ} is known [see 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 α_{0} and α_{2} are reported at E_{d} = 0.39 to 3.9 MeV and at 12 MeV [see (1974AJ01, 1979AJ01)]. Recent measurements for E_{cm} = 57  141 keV were reported by (1997YA02, 1997YA08). Astrophysical Sfactors were deduced. 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) state is to ^{5}He_{g.s.} + α while ^{9}Be*(3.1, 4.7) states decay to ^{8}Be_{g.s.} + n. It should be noted, however, that the peaks corresponding to ^{9}Be*(3.0) have a FWHM of ≈ 1 MeV, which may imply that ^{9}Be*(2.8) is involved.
See (1986BU22, 1987BU1A, 1987VO08, 1988BU06). More recently, the reaction was studied at E_{γ} = 150  400 MeV with tagged photons (1999MC06).
Angular distributions of the α_{0} group have been measured at E_{n} = 13.9 to 18.8 MeV [see (1974AJ01)] and at 14.1 MeV (1984HA48). ^{9}Be*(1.7, 2.4, 3.1, 6.8) are also populated. Cross sections and particlespectra related to neutron detector development have been measured at E_{n} = 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 E_{n} = 13 to 18 MeV involves ^{9}Be*(2.4). See (1984HA48) for differential cross sections at 14.1 MeV and for partial and total cross sections.
See (1985DE17; E_{p} = 58 MeV), and the calculations of (1987ZH10; E_{p} ≈ 0.7 GeV).
Differential cross sections were measured at E_{t} = 33 MeV to ^{9}Be_{g.s.} (1989SI02). Spectroscopic factors for ^{3}Hecluster pickup were deduced.
Cross section measurements at E_{α} = 90 MeV and DWBA analysis are reported in (1991GL03). See also ^{7}Be in (2002TI10).
For reaction (a) see ^{10}B. Differential cross sections for reaction (b) were measured at E(^{12}C) = 480 MeV (1988KR11). For reaction (c) see (1988KR11) and (1985OS06). For reaction (d) see (1986GO1B; E(^{14}N) = 150 MeV).
Differential cross sections were measured at E_{t} = 33 MeV to ^{9}Be*(0, 2.43) (1989SI02). Spectroscopic factors for αcluster pickup were deduced.
Angular distributions have been obtained at E(^{3}He) = 70 MeV for the transitions to ^{9}Be*(0, 2.4) and ^{7}Be*(0, 0.43). Broad states at 2.9, 4.8 ± 0.2, 7.3 ± 0.2 and 11.9 ± 0.4 MeV are also populated: see (1979AJ01).
See ^{8}Be here and ^{9}Be in (1979AJ01).
See (1986GO1B; E(^{14}N) = 150 MeV).
See ^{20}Ne in (1987AJ02). See also (1985KA1J).
