
^{8}Be (1974AJ01)(See Energy Level Diagrams for ^{8}Be) GENERAL: See also (1966LA04) and Table 8.3 [Table of Energy Levels] (in PDF or PS). Shell model: (1965CO25, 1965VO1A, 1966BA26, 1966GU06, 1966HA18, 1966PA15, 1967BA1K, 1967BO1C, 1967HS1A, 1967PA10, 1967ST1C, 1967SV1A, 1968BA1L, 1968FA1B, 1968GO01, 1969AB1D, 1969GU1E, 1969GU03, 1969IK1A, 1969KU1F, 1969SV1A, 1970BA75, 1970BO1J, 1970CO1H, 1970DE1F, 1970GU11, 1970KO04, 1970KR1D, 1970NO1C, 1970RU1A, 1970TU01, 1970WO12, 1970ZO1A, 1971BO22, 1971BO29, 1971CO28, 1971GU20, 1971HA1U, 1971NO02, 1972AB12, 1972BO38, 1972HA05, 1972LE1L, 1973BO07, 1973HA05, 1973HA49, 1973JO1K). Collective and deformed models: (1962MO1B, 1965VO1A, 1967LA09, 1967PA10, 1969AB05, 1969RU04, 1970BO41, 1970GO1Q, 1971BO22, 1971BO29, 1971HO19, 1972AB1C, 1972BO38, 1972HA05, 1972HO56, 1973BO07, 1973HO40, 1973KO1F, 1973KU13, 1973PE08). Cluster and αparticle model: (1965IN1A, 1965NE1B, 1966KA1A, 1966PA15, 1966WE1C, 1969AB1B, 1969AB1D, 1969IK1A, 1969KU1C, 1969KU1F, 1969ME1C, 1969TA1C, 1970BA75, 1970YU1B, 1971AB07, 1971AB1B, 1971FR06, 1971KH06, 1971LE1N, 1971NO02, 1972AB1C, 1972AB19, 1972AK10, 1972BA59, 1972FR1B, 1972GR42, 1972HA05, 1972HI16, 1972HO56, 1972IK1A, 1972LE1L, 1972VA45, 1973HO40). Special levels: (1966BA26, 1966BR1H, 1966DA02, 1966GU06, 1966PA15, 1966ST1D, 1967BA1N, 1967HO03, 1967HS1A, 1967MA1B, 1967ST1C, 1968GO01, 1968LA1B, 1969BA43, 1969GU03, 1969HA1G, 1969HA1F, 1969SH1A, 1970BO1J, 1970KI1D, 1970PE18, 1970RU1A, 1971AN03, 1971CO28, 1971GU20, 1971NO02, 1972BE1E, 1972HA1R, 1972VA45, 1973AS02, 1973BO07, 1973FE1J, 1973HO40, 1973MA1K, 1973ST1Q). Electromagnetic transitions: (1965CO25, 1966BA26, 1966PA15, 1966WA1E, 1967HS1A, 1968LA1B, 1969AB05, 1969HA1G, 1969HA1F, 1971BO22, 1972AB12, 1972BO38, 1972HA05, 1972NA05, 1973AS02, 1973BO07, 1973HA49, 1973HA1Q). Special reactions: (1966ME1D, 1967GO1F, 1968BA61, 1968CH1F, 1969DE1M, 1969VI1C, 1970RA1J, 1972BI10, 1972CR1F, 1972HA2F, 1973JO07, 1973KO1P). Other topics: (1965CO25, 1965VO1A, 1966DA02, 1966GU06, 1966HA18, 1966PA15, 1966TO04, 1966YO1B, 1967BA1K, 1967BA12, 1967BA1M, 1967BO1G, 1967BO1C, 1967BR1E, 1967CA17, 1967DI1B, 1967LA09, 1967LA1G, 1967PA10, 1967SV1A, 1968BA1L, 1968FA1B, 1968GO01, 1968LA1B, 1968NE1C, 1969AB05, 1969GU03, 1969KU1F, 1969HO1M, 1969KE1B, 1969NA1E, 1969NA1L, 1969RU04, 1969SH1A, 1969SV1A, 1970BA75, 1970BO1J, 1970CO1H, 1970GR44, 1970HO1J, 1970KO04, 1970KR1D, 1970NO1C, 1970PE18, 1970RU1A, 1970TU01, 1970ZO1A, 1971AN03, 1971DE1V, 1971GR2C, 1971HO19, 1971JE1B, 1971SO11, 1971ST40, 1971ZA1D, 1972AB12, 1972AN05, 1972EL1C, 1972FR1B, 1972HA05, 1972HA57, 1972LE1L, 1972LE23, 1972PN1A, 1972VA45, 1973HA05, 1973JO1K, 1973JU2A, 1973KO26, 1973NA26, 1973RA1E, 1973RO1R, 1973ST1Q). Ground state: (1965CO25, 1965VO1A, 1966BA26, 1966TO1B, 1967BO1G, 1967BR1E, 1967LA1G, 1967PA10, 1968BA1L, 1968BO19, 1968FA1B, 1969AB05, 1969GU03, 1969KE1B, 1969KU1F, 1970GR44, 1970KO04, 1970KR1D, 1970TU01, 1971BO29, 1971GR2C, 1971RU14, 1972AB12, 1972GR42, 1972LE1L, 1972VA45, 1973KO26, 1973MA1K). Adjusted mass excess^{†} of ^{8}Be: 4941.87 ± 0.13 keV (1972WA1G). ^{†} Not used in Q_{m} calculations in this paper.
In α  α scattering (reaction 4) the Q_{0} is found to be 92.12 ± 0.05 keV, Γ_{c.m.} = 6.8 ± 1.7 eV (1968BE02). See also (1966LA04) for earlier values.
Radiative widths have been measured for ^{8}Be*(16.6, 16.9): see (1974NA1H: E_{α} = 31 to 35 MeV).
For reaction (a) see (1952WA31). For reaction (b) see ^{7}Li.
Alpha  α scattering reveals the ground state as a resonance with Q_{0} = 92.12 ± 0.05 keV, Γ_{c.m.} = 6.8 ± 1.7 eV, [τ = (0.97 ± 0.24) × 10^{16} sec] (1966BE05, 1968BE02). Effective range theory analysis of higher energy scattering yields widths consistent with this value but subject to considerable uncertainty (1966TO1B). However, (1967KE1B, 1967KE1E) and (1967RA1B) have carried out such analyses yielding Γ = 6.14 ± 0.04 eV and 6.4^{+}0.8_{0.5} eV, respectively. Using a threelevel, onechannel Rmatrix formalism (1968BA2D) find Γ = 5.1 ± 0.4 eV for the ground state of ^{8}Be. Rmatrix analysis of the swave scattering and of the ^{9}Be(p, d)^{8}Be reaction indicates the presence of a second 0^{+} state at E_{x} ≈ 6 ± 3 MeV, Γ = 9 ± 4 MeV (a_{0} = 7 fm) (1968BA2D). For E_{α} = 30 to 70 MeV the l = 0 phase shift shows resonant behavior at E_{α} = 40.7 MeV, corresponding to a 0^{+} state at E_{x} = 20.2 MeV, Γ < 1 MeV, Γ_{α}/Γ < 0.5. No evidence for other 0^{+} states is seen above E_{α} = 43 MeV (1972BA83). The dwave phase shift becomes appreciable for E_{α} > 2.5 MeV and passes through resonance at E_{α} = 6 MeV (E_{x} = 3.18 MeV, Γ = 1.5 MeV, J^{π} = 2^{+}) (1963TO02). See Table 8.4 (in PDF or PS). Analyses by manylevel Rmatrix theory of the αscattering, of the ^{9}Be(p, d)^{8}Be reaction and of the ^{8}Li and ^{8}B βdecays lead to approximately correct values for the E_{x} and Γ of ^{8}Be*(2.9) and suggest a second 2^{+} state at E_{x} ≈ 8.5 MeV, Γ ≈ 10.5 MeV (1969BA43: a_{2} = 6.75 fm), E_{x} = 12.0^{3.0}_{+3.5} MeV, Γ = 14^{3}_{+4} MeV (1969CL10: a_{2} = 6.0 ± 0.5 fm). Five 2^{+} levels are observed from the l = 2 phase shifts measured from E_{α} = 30 to 70 MeV: ^{8}Be*(16.6, 16.9) with Γ_{α} = Γ, and states with E_{x} = 20.2, 22.2 and 25.2 MeV. The latter has a small Γ_{α} (1972BA83). See also reaction 11. The l = 4 shift rises from E_{α} ≈ 11 MeV and indicates a broad 4^{+} level at E_{x} = 11.4 ± 0.3 MeV (1959BR71). See also (1973CH1W). A rapid rise of δ_{4} at E_{α} = 40 MeV corresponds to a 4^{+} state at 19.9 MeV with Γ_{α}/Γ ≈ 0.96; Γ < 1 MeV and therefore Γ_{α} < 1 MeV, which is < 5% of the Wigner limit. A broad 4^{+} state is also observed near E_{α} = 51.3 MeV (E_{x} = 25.5 MeV) but there is no evidence for a previously reported state at E_{x} = 27.5 MeV (1972BA83). Over the range E_{α} = 30 to 70 MeV a gradual increase in δ_{6} is observed (1972BA83). Some indications of a 6^{+} state at E_{x} ≈ 28 MeV and of an 8^{+} state at ≈ 57 MeV have been reported by (1965DA11), with Γ_{c.m.} ≈ 20 and ≈ 73 MeV, respectively. The elastic scattering has been studied at E_{α} = 140 MeV by (1972FR1K). For a listing of the older work see Table 8.7 (in PDF or PS) [(dσ/dΩ)], Table 8.8 (in PDF or PS) [parameters of ^{8}Be states from ^{4}He(α, α)] and Table 8.9 (in PDF or PS) [parameters of ^{8}Be*(2.9)] in (1966LA04). See also (1972FR1J). For studies of inelastic scattering of αparticles from ^{4}He see (1969GR06, 1971HA41) and the review in (1973FI04). See also (1965SL1A, 1967ST30, 1968CO1M). The bremsstrahlung cross section has been measured at E_{α} = 9.35 MeV and for E_{α} = 11.4 to 13.5 MeV: no significant enhancement is found at the final state energy corresponding to ^{8}Be*(2.9) (1972FR02, 1973FR17). The cross section has also been measured for E_{α} = 12.1 to 18.7 MeV by (1972PE16). See also (1965PR1A, 1965TA1D, 1966AB1A, 1966AL1G, 1966EN1A, 1966HI1A, 1966OK1A, 1967AB1A, 1967AL1E, 1967BE1N, 1967CH1H, 1967KE1C, 1967KE10, 1967PA1E, 1968BA1H, 1968HA1G, 1968HA1C, 1968KE1E, 1968PA1L, 1968SA1F, 1968SH1G, 1968TA1L, 1968TK1A, 1969AF1B, 1969BA1W, 1969BA1Y, 1969DO03, 1969KE1D, 1969KE09, 1969RE12, 1969SA1D, 1969TH06, 1969TR1C, 1970CH1P, 1970CH1R, 1970EF01, 1970FE1C, 1970KH1C, 1970KU15, 1970LO1F, 1970PI1B, 1971BR30, 1971GR39, 1971KU10, 1971KU22, 1971LE23, 1971MU1H, 1971NE1C, 1971PI1F, 1971RE1F, 1972DE29, 1972GI1G, 1972GO16, 1972HI16, 1972KA1K, 1972ME23, 1972OK02, 1973GR1M, 1973HA57, 1973PE08, 1973RA27, 1973YU1A; theor.).
Not observed: (1953SA1A, 1954SI07).
The yield curve has been measured for E_{d} = 0.06 to 5.5 MeV [see (1966LA04) and (1966SC26)], and at E_{d} = 12 to 17 MeV (1970GA07: population of ^{7}Be*(0 + 0.43)). A broad swave resonance is indicated at E_{d} = 0.41 MeV, Γ = 0.45 MeV (1952BA64, 1956NE13). Polarization measurements are reported at E_{d} = 0.27 to 0.60 MeV (1966MI06; n_{1}) and 2.5 to 3.7 MeV (1970TH08; n_{0}, n_{1}). The distributions observed by (1970TH08) are quite constant over the range 2.5 to 3.7 MeV, indicating that the predominant reaction mechanism is direct. See also ^{7}Be. Comparisons of the populations of ^{7}Be*(0, 0.43) and of ^{7}Li*(0, 0.48) have been made at many energies, up to E_{d} = 7.2 MeV. The n/p ratios are closely equal for analog states, consistent with charge symmetry (1957WI24, 1963BI27, 1963CR08). See also (1966AU1A).
Excitation functions have been measured for E_{d} = 30 keV to 5.4 MeV [see (1966LA04) and (1966LO18, 1968BE1P, 1969BL14)]. A broad maximum near E_{d} = 1.0 MeV is interpreted as indicating a level at E_{d} = 0.4 MeV (1950WH02). In the range E_{d} = 1 to 5 MeV there is evidence for both direct interaction and compound nucleus formation (1963BI27, 1963ME09, 1964PA06): at back angles the (d, p_{1}) data show evidence of the E_{d} = 3.7 MeV resonance [see ^{6}Li(d, α)^{4}He]. An anomaly is observed in the p_{1}/p_{0} intensity ratio at E_{d} = 6.945 MeV, corresponding to the J^{π} = 0^{+}; T = 2 analog of the ground state of ^{8}He: E_{x} = 27.483 ± 0.010 MeV, Γ = 10 ± 3 keV, Γ_{p0} ≪ Γ_{p1}, Γ_{p0} < Γ_{d} (1969BL14). The parameters of this state have been calculated by (1969BA36). Polarization measurements have been made at E_{d} = 0.6 and 0.96 MeV (1969NA1J, 1972SE09; p_{0}, p_{1}) and at E_{d} = 2.1 to 10.9 MeV (1968DU09, 1968FI07, 1970FI07; p_{0}, p_{1}). The latter report pronounced differences in the angular distributions of the vector analyzing power of the two l_{n} = 1 transitions to ^{7}Li*(0, 0.48). See also (1972FI1E, 1973FI1C). For reaction (b) see (1966FR06). See also ^{7}Li and (1966AU1A, 1966BR25).
The yield of elastically scattered deuterons has been measured for E_{d} = 2 to 4.8 MeV (1964PA06), 4.0 to 6.5 MeV (1966BR1J), and 6.33 to 7.14 MeV (1969BL14): no resonances are reported. At E_{d} = 12.0 MeV, θ_{lab} = 95°, the differential cross section for elastic scattering is 9.82 ± 0.20 mb/sr (1971BI11). See also ^{6}Li and (1972FI1E, 1973FI1C).
The cross section for tritium production rises rapidly to 190 mb at 1 MeV, then more slowly to 290 mb near 4 MeV. There is evidence of deviation from isotropy near 0.4 MeV (1955MA20). See also ^{5}Li.
See ^{5}He.
Cross sections and angular distributions (reaction (a)) have been measured for E_{d} = 0.03 to 12 MeV: see (1966LA04) and (1969LE22: E_{d} = 40 to 130 keV), (1966LO18: 0.2 to 2 MeV), (1968BE1P: 0.3 to 1.0 MeV), (1965RO1E, 1969DE31, 1969HU17: 0.35 to 1.50 MeV), (1966BR25: 1.0 to 2.0 MeV), (1964AN1A: 1.0 to 2.5 MeV), (1967CL06: 3 to 12 MeV) and (1969BL14: 6.33 to 7.14 MeV). Polarization measurements are reported at E_{d} = 0.40, 0.60, 0.80, 0.96 MeV (1971NE12, 1972SE09), 0.7 to 2.2 MeV (1967PL02), 2.1 to 10.9 MeV (1968DU07), 4.3, 6.3, 8.0, 10.1 and 11.8 MeV (1968BU13) and at E(^{6}Li) = 0.6 MeV (1970HO11). See also (1967BU1B, 1972KO1P). Maxima are observed at E_{d} = 0.8 MeV, Γ_{lab} ≈ 0.8 MeV and E_{d} = 3.75 MeV, Γ_{lab} ≈ 1.4 MeV (1963ME09, 1964PA06). Analysis of these and other data up to E_{d} = 12 MeV indicate a 2^{+}, 0^{+}, (6^{+}), 2^{+}, 4^{+} sequence of states: see Table 8.10 (in PDF or PS) in (1966LA04) (1965FR02, 1967CL06). See, however, reaction 4. The assignment of J^{π} = 2^{+} to ^{8}Be*(22.2) is consistent with the polarization information (1971NE12, 1972SE09), but the 0^{+} state may actually be virtual with respect to ^{6}Li + d (1972SE09) [^{8}Be*(20.3): see reaction 4 and (1972BA83)]. At E_{d} = 6.945 MeV, the αyield shows an anomaly corresponding to ^{8}Be*(27.48), the J^{π} = 0^{+}; T = 2 analog of the ^{8}He ground state (1969BL14). See also reaction 7 and (1969BA36; theor.). See also (1966LE1C), (1971PL1C) and (1967TS1A, 1968CO1L, 1968KO1G, 1969CH1J, 1970FI11; theor.). For reactions (b), (c) and (d), see (1972HA34) and (1973FI04).
For reaction (b) see (1966LA02, 1967BE13, 1967BI1D). See also (1966LA04).
Proton groups are observed to ^{8}Be*(0, 2.9, 16.63, 16.91, 17.64): see (1966LA04) and Tables 8.4 (in PDF or PS) and 8.5 (in PDF or PS). The excitation of ^{8}Be*(18.15, 19.0, 19.4, 19.9) is also reported by (1971GL07). Angular distributions have been measured at E(^{3}He) = 1.4 to 1.8 MeV (1969VI05; p_{0}, p_{1}) and 5, 6, 7, 9, 10, 13 and 17 MeV (1965FL03; p_{0}, p_{1}; PWBAE analysis). A gradual change is observed from a dominant back angle maximum to a dominant forward maximum (1965FL03). Measurements of the energies of all the particles emitted in this reaction and reactions 23, 38 and 42 show that the apparent width of ^{8}Be*(2.9) does not depend on the relative velocity of the spectator particle: E_{x} = 2.83 ± 0.20 MeV, Γ = 1.75 ± 0.30 MeV (1969NU01). See also Table 8.4 (in PDF or PS). Reaction (b) proceeds via ^{8}Be*(16.63, 16.91): Γ = 117 ± 10 and 85 ± 10 keV, respectively. Interference effects are observed (1969VI05). See also ^{5}Li and (1967RE03, 1968RE10, 1972TH08). See also (1964MA57, 1968VI03, 1970GA1G, 1971TR1B), (1967HO1C) and (1967BA1E, 1968HE1F, 1969TH1D, 1970DE41, 1973ED02; theor.).
Deuteron groups have been observed to ^{8}Be*(0, 2.9, 11.3 ± 0.4) (1959ZE1A, 1962CE01). Angular distributions have been measured at E_{α} = 20 and 24 MeV (1973GR1N), 20.5 to 24.5 MeV and at 38 MeV (1965DE1F; d_{0}), 43 MeV (1959ZE1A; d_{0}, d_{1}) and 48 MeV (1962CE01; d_{0}, d_{1}). At E_{α} = 12 MeV (θ = 15° and 20°) the deuteron spectrum does not show a "ghost" anomaly at E_{x} = 0.1  0.5 MeV (1971BE52). A study of reaction (b) shows that the peak due to ^{8}Be*(2.9) is best fitted by using Γ = 1.2 ± 0.3 MeV (1969BA18): see also Table 8.4 (in PDF or PS). See also (1968LA1E) and (1971BU1K; theor.). For reaction (b) see ^{6}Li. See also (1966LA04).
This reaction proceeds via ^{8}Be*(0, 2.9, 16.6, 16.9, 22.5), and there is indication also that the direct threebody breakup (reaction (b)) is possible (1971GA1N, 1971GA21, 1972GA32: E_{max}(^{6}Li) = 13.0 MeV). The involvement of a state at E_{x} = 19.9 MeV (Γ = 1.3 MeV) is suggested by (1966MA40). See also (1971GL07). Good agreement with the shapes of the peaks corresponding to ^{8}Be*(16.6, 16.9) is obtained by using a simple twolevel formula with interference, corrected for the effect of final state Coulomb interactions, assuming Γ(16.6) = 90 and Γ(16.9) = 70 keV: see also Table 8.5 (in PDF or PS) (1971NO04). See also (1968NO03, 1969IN06). The ratio of the intensities of the groups corresponding to ^{8}Be*(16.6, 16.9) remains constant for E(^{6}Li) = 4.3 to 5.5 MeV: I(16.6)/I(16.9) = 1.22 ± 0.08 (1966KI09, 1966MA40). Partial angular distributions for the α_{0} group have been measured at fourteen energies for E(^{6}Li) = 4 to 24 MeV (1970FR06). For reaction (b) see also (1966BE22). For a review of the older work see (1966LA04). See also (1964MA26, 1967AL1F, 1967CH34, 1968DA20, 1971PO1D), (1966BR1G, 1967CA1D), (1966BA1T, 1966EL1A, 1966RO1E, 1966RO1F, 1966RO1H, 1972JO1D; theor.) and ^{12}C.
Cross sections and angular distributions have been reported from E_{p} = 30 keV to 18 MeV. Gamma rays are observed to the ground (γ_{0}) and to the broad, 2^{+}, excited state at 2.9 MeV (γ_{1}) and to ^{8}Be*(16.6, 16.9) (γ_{3}, γ_{4}). Resonances for both γ_{0} and γ_{1} occur at E_{p} = 0.44 and 1.03 MeV, and for γ_{1} alone at 2, 4.9, 6.0, 7.3, and possibly at 3.1 and 11.1 MeV. In addition broad resonances are reported at E_{p} ≈ 5 MeV (γ_{0}), Γ ≈ 4  5 MeV, and at E_{p} ≈ 7.3 MeV (γ_{1}), Γ ≈ 8 MeV. The E_{p} ≈ 5 MeV resonance (E_{x} ≈ 22 MeV) represents the giant dipole resonance based on ^{8}Be(0) while the γ_{1} resonance, ≈ 2.3 MeV higher, is based on ^{8}Be*(2.9). The γ_{0} and γ_{1} giant resonance peaks each contain about 10% of the dipole sum strength (1966FI1B, 1968BL1E, 1970FI1B). The main trend between E_{p} = 8 and 17.5 MeV is a decreasing cross section (1970FI1B). See, however, (1967FE04). See also Table 8.6 (in PDF or PS). At the E_{p} = 0.44 MeV resonance (E_{x} = 17.64 MeV) the radiation is nearly isotropic consistent with pwave formation, J^{π} = 1^{+}, with channel spin ratio σ(J_{c} = 2)/σ(J_{c} = 1) = 3.2 ± 0.5 (1961ME10). Radiative widths for the γ_{0} and γ_{1} decay are displayed in Table 8.7 (in PDF or PS). The E2/M1 amplitude ratio for the 17.6 → 2.9 transition varies over the energy of the broad final state: the average value is δ = 0.21 ± 0.04 (1967CO19). See also (1967CO29). ^{8}Be*(16.63, 16.91) are 2^{+} states with mixed T = 0, 1 isospin [see (1965MA1G, 1966MA03, 1968PA09, 1969SW01)], with the lower state of ^{7}Li + p parentage and the higher of ^{7}Be + n parentage (1965SW03, 1968PA09). A careful study of the αbreakup of ^{8}Be*(16.63, 16.91) for E_{p} = 0.44 to 2.45 MeV shows that the nonresonant part of the cross section for production of ^{8}Be*(16.63) is accounted for by an extranuclear directcapture process. Resonances for production of ^{8}Be*(16.63, 16.91) are observed at E_{p} = 0.44, 1.03 and 1.89 MeV [^{8}Be*(17.64, 18.15, 18.9)]. The results are consistent with the hypothesis of nearly maximal isospin mixing for ^{8}Be*(16.63, 16.91): decay to these states is not observed from the 3^{+} states at E_{x} = 19 MeV, but rather from the 2^{} state at 18.9 MeV excitation (1969SW01). See also reaction 17. (1968PA09) find squared T = 1 components of 40% and 60% in ^{8}Be*(16.6, 16.9) and of 95% and 5% in ^{8}Be*(17.6, 18.2). Gamma  α angular correlation measurements at E_{p} = 0.44 MeV show that the 17.64 → 16.63 γ is nearly pure M1 δ(E2/M1) = 0.014 ± 0.013 (1969SW02). See also (1965SW03). Radiative widths are shown in Table 8.7 (in PDF or PS). For a review of the earlier work, see (1959AJ76, 1966LA04). See also (1973SU1E), (1966EV1B, 1966PE1D, 1966WA1C, 1969KA1J), and (1973AS02; theor.).
Recent measurements of cross sections have been made for E_{p} = 1.9 to 2.36 MeV (1967BE61; σ_{t}), 1.93 to 2.66 MeV (1969LE23), 2.1 to 3.8 MeV (1971BU1D), 2.4 to 6.0 MeV (1972PR03; n_{1}γ), 2.6 to 5.4 MeV (1972EL19; n_{0}), 3 to 10 MeV (1966HA1J; n_{1}γ), 3.2 to 5.4 MeV (1972EL19; n_{1}), 23 to 52 MeV (1967LO07; n_{1}γ), and 30 and 50 MeV (1969CL06; n_{0}, n_{1}). See also (1973WA34). The shape of the neutron yield near threshold has been studied by (1966PA03). Polarization measurements are reported at E_{p} = 2.05 to 3.00 MeV (1973RO35, 1973RO2E), 3.0 to 4.0 MeV (1971HA27; n_{0}, n_{1}), 3.0 to 5.5 MeV (1971TH07; n_{0}, n_{1}) and 30 and 50 MeV (1969RO20). For a report on the earlier yield and polarization measurements, see (1966LA04). For angular distributions, see ^{7}Be. The yield of ground state neutrons (n_{0}) rises steeply from threshold and shows pronounced resonances at E_{p} = 2.25 and 4.9 MeV (1963BO06). The yield of n_{1} also rises steeply from threshold (1964BU08) and exhibits a broad maximum near E_{p} = 3.2 MeV (1961BE05, 1972PR03) and a broad dip at E_{p} ≈ 5.5 MeV, also observed in the p_{1} yield (1972PR03). Multichannel scattering length approximation analysis of the 2^{} partial wave near the n_{0} threshold indicates that the 2^{} state at E_{x} = 18.9 MeV is virtual relative to the threshold and that its width Γ = 50 ± 20 keV (1974AR10). The ratio of the cross section for ^{7}Li(p, γ)^{8}Be*(18.9) γ / → ^{8}Be*(16.6 + 16.9) [obtained by (1969SW01)] to the thermal neutron capture cross section ^{7}Be(n, γ)^{8}Be*(18.9) γ / → ^{8}Be*(16.6 + 16.9) [obtained by (1973BA1J)], provides a rough estimate of the isospin impurity of ^{8}Be*(18.9): σ_{p,γ}/σ_{n,γ} ≈ 1.5 × 10^{5} and therefore the T = 1 isospin impurity is < 4% in intensity (1974AR10). The structure at E_{p} = 2.25 MeV is ascribed to a 3^{+}, T = (1), l = 1 resonance with Γ_{n} ≈ Γ_{p} and γ^{2}_{n}/γ^{2}_{p} = 3 to 10: see (1966LA04). See also (1973RO35). At higher energies the broad peak in the n_{0} yield at E_{p} = 4.9 MeV can be fitted by J^{π} = 3^{(+)} with Γ = 1.1 MeV, γ^{2}_{n} ≈ γ^{2}_{p} (1963BO06). The behavior of the n_{1} cross section can be fitted by assuming a 1^{} state at E_{x} = 19.5 MeV and a J = 0, 1, 2, positiveparity state at 19.9 MeV [presumably the 20.2 MeV state reported in reaction 4]. In addition the broad dip at E_{p} ≈ 5.5 MeV may be accounted for by the interference of two 2^{+} states (1972PR03). See Table 8.8 (in PDF or PS). The ratio of the cross sections of the (p, n_{1}) reaction to ^{7}Be*(0.43) to that for the (p, p_{1}) reaction to the analog state ^{7}Li*(0.48) has been measured for E_{p} = 2.4 to 6.0 MeV (1972PR03), 3 to 10 MeV (1966HA1J) and 23 to 52 MeV (1967LO07). At the lower energies it deviates markedly from unity and varies strongly with energy (1966HA1J). At the higher energies the measurements seem to indicate that the spinflip, isospinflip part of the effective interaction is essentially independent of energy while the pure central part appears to decrease as the energy increases (1967LO07). See also (1969CL06). See also (1968DA1H, 1970DA26, 1971JU05, 1971SC32, 1973AR1R, 1973NE1G), (1971WA1D) and (1970HO04, 1970LU1A, 1970RA33; theor.).
Absolute differential cross sections for elastic scattering have been reported for E_{p} = 0.4 to 12 MeV (1953WA27, 1956MA12, 1965GL03), 14.5, 20.0 and 31.5 MeV (1956KI54) and more recently at 0.85 to 2.0 MeV (1966BA1Q), at 1.36 MeV (1969LE08) and at 6.868 MeV (1971BI11). The yield of inelastically scattered protons (p_{1}, to ^{7}Li*(0.48)) and of 0.48 MeV γrays have been measured in the range E_{p} = 0.8 to 12 MeV (1951BR10, 1954KR06, 1954MO04, 1955HA34, 1957NE22, 1965GL03, 1966BA1Q, 1972PR03). Polarization measurements are reported at E_{p} = 0.67 to 2.45 MeV (1973BR13; p_{0}), 2.7 to 10.6 MeV (1969KI04; p_{0}, p_{1}), 14.5 MeV (1965RO22; p_{0}), 49.8 MeV (1971MA13, 1971MA44; p_{0}, p_{1}), 152 MeV (1966RO1C; p_{0}) and 155 MeV (1968GE04; p_{0}, p_{2}). For earlier measurements see (1966LA04). For a summary of angular distribution studies see ^{7}Li. Anomalies in the elastic scattering appear at E_{p} = 0.44, 1.03, 1.88, 2.1, 2.5, 4.2 and 5.6 MeV. Resonances at E_{p} = 1.03, 3 and 5.5 MeV and an anomaly at E_{p} = 1.88 MeV appear in the inelastic channel. A phase shift analysis and a review of the existing cross section data by (1973BR13) show that the 0.44 and 1.03 MeV resonances are due to 1^{+} states which are a mixture of ^{5}P_{1} and ^{3}P_{1} with a mixing parameter of +25°; that the 2^{} state at the neutron threshold (E_{p} = 1.88 MeV) has a width of about 50 keV [see also reaction 17]; and that the E_{p} = 2.05 MeV resonance corresponds to a 3^{+} state. The anomalous behavior of the ^{5}P_{3} phase around E_{p} = 2.2 MeV appears to result from the coupling of the two 3^{+} states [resonances at E_{p} = 2.05 and 2.25 MeV]. The ^{3}S_{1} phase begins to turn positive after 2.2 MeV suggesting a 1^{} state at E_{p} = 2.5 MeV (1973BR13): see Table 8.9 (in PDF or PS) and (1972PR03). An attempt has been made to find the T = 2 analog of the ground state of ^{8}He: no resonances were observed in either the p_{0} or the p_{1} yield for E_{p} = 11.1 to 11.9 MeV (1968HA1H). Measurements of the intensity ratios of the reactions (p, p_{1}) and (p, n_{1}) have been made by (1966HA1J, 1967LO07, 1972PR03): see reaction 17. See also (1967CA1G, 1972RU1C) and (1967JO01, 1967SA1C, 1969WA11; theor.).
See (1969KO1P; theor.) and ^{6}Li.
See ^{5}Li.
The cross section follows the expression E^{1}e^{B/√E (square root of E)}, with B = 91.5 ± 4.5 keV^{1/2}, in the range E_{p} = 23 to 50 keV. The cross section in that interval rises from 0.013 to 2.4 μb (1967FI05). In the range E_{p} = 131 to 561 keV, the cross section increases from 0.16 ± 0.02 to 3.7 ± 0.4 mb (1971SP05; and T.A. Tombrello, private communication). The cross section has also been measured for E_{p} = 0.04 to 0.13 MeV by (1969LE22). Taking into account ^{8}Be J^{π} = 2^{+} levels at 16.7, 16.9 and 20.6 MeV, (1972BA41) has made an Rmatrix fit to the revised data of (1971SP05) and has obtained a quadratic energy dependence for the Sfactor: S = 0.065[1 + 1.82E  2.51E^{2}] MeV · b, over the energy range E_{p} = 0 to 600 keV. Excitation functions and angular distributions have been measured at many energies up to 18.6 MeV: see (1966LA04) for earlier references. Recently, differential crosssection measurements are reported by (1966MA03, 1969SW01: E_{p} = 0.4 to 2.45 MeV), (1969LE08: E_{p} = 1.36 MeV) and (1967CR05: E_{p} = 41.3 and 45.2 MeV). Polarization measurements have been carried out for E_{p} = 0.8 to 3 MeV (1968PE03), 2.7 to 10.6 MeV (1969KI04), 3.00 to 10.04 MeV (1968PL01), 5.5 to 6.7 MeV (1966BO09), and 7.4 to 10.4 MeV (1968AR04). See also (1966LA04) for a listing of the earlier references and (1966DA1B, 1971PL1C). In the range E_{p} = 3 to 10 MeV the asymmetry has one broad peak in the angular distribution at all energies except near 5 MeV; the peak value is 0.98 ± 0.04 at 6 MeV and is essentially 1.0 for E_{p} = 8.5 to 10 MeV (1968PL01, 1969KI04) [see Fig. 12 in (1969KI04) and Fig. 6 (1968PL01) for contour maps of the asymmetry]. Broad resonances are reported to occur at E_{p} = 3.0 MeV, Γ ≈ 1 MeV (1948HE01) and at E_{p} = 5.6 MeV, Γ ≈ 1 MeV (1961HA27 (and private communication), 1962TE04, 1964MA51). Some structure is also reported near E_{p} = 6.0 to 6.5 MeV, and at E_{p} = 9.0 MeV (1964MA51). The latter is also reflected in the behavior of the A_{2} coefficient (1968PL01). The experimental data on yields and on polarization have been analyzed by (1970KU1H, 1971KU10): the data appear to require including two 0^{+} states [at E_{x} ≈ 19.7 and 21.8 MeV] with very small αparticle widths, and four 2^{+} states [at E_{x} ≈ 15.9, 20.1, 22.2 and 25 MeV]. See, however, reaction 4 and (1972BA83). A 4^{+} state near 20 MeV was also introduced in the calculation but its contribution was negligible. The observed discrepancies are said to be probably due to the assumption of pure T = 0 for these states (1971KU10). See also (1968CO1L, 1968CO1M, 1970CO1M), (1969AU1C, 1972BA2M, 1973TR1E; astrophys. considerations), (1967BO38, 1969DA1G, 1970PE1D). At E_{p} = 9.1 MeV, αparticle spectra are discussed in terms of the first excited state of ^{4}He (1970LI06): see (1973FI04).
At E_{d} = 2 MeV, recoil proton spectra show only the ground state and ^{8}Be*(2.9). No other groups with E_{x} < 9 MeV appear with intensity > 10% of n_{0}. The spectrum yields E_{x} = 3.1 ± 0.1, Γ = 1.75 ± 0.1 MeV (1964JO04) [(1971RO05) report E_{x} = 3.10 ± 0.09, Γ = 1.74 ± 0.08 MeV]. See Table 8.4 (in PDF or PS). At higher deuteron energies the population of ^{8}Be*(16.6, 16.9, 17.6, 18.2, 18.9, 19.1, 19.2) is reported and l_{p} = 1 is obtained for the transitions to ^{8}Be*(16.6, 17.6, 18.2): see (1960DI02, 1966DI1B, 1967KE1A, 1967KE1F). Angular distributions of the n_{0} and n_{1} groups to ^{8}Be*(0, 2.9) are reported by (1966JU1A: E_{d} = 0.7 and 0.8 MeV), (1969NU1C: E_{d} = 0.90 to 1.09 MeV), (1966MI09: E_{d} = 1 MeV), and by (1970OSZY: E_{d} = 1.62 to 2.97 MeV). See also (1966LA04) for earlier references, (1966MA1J, 1966NU1B, 1966PO1D, 1968SA14, 1970SA20, 1970SA25, 1970SA29, 1973JO1L, 1973WE19) and the important theoretical paper by (1969BA43). Reaction (b) appears to proceed primarily by sequential decay via ^{8}Be*(2.9, 16.6, 16.9) and ^{5}He(0): see (1967VA11). See also (1966AS04, 1966MI09, 1967JE01, 1972DE44, 1973HE26, 1973MC13). However, (1969HO11) deduce the involvement of a state with E_{x} = 11.4 ± 0.05 MeV, Γ_{c.m.} = 2.8 ± 0.2 MeV. See also (1973KA32). Attempts to observe n  α rescattering ("proximity scattering") proceeding via ^{8}Be*(16.6, 16.9) have been unsuccessful: see (1968VA12, 1971SW10, 1972BR08). See also (1969TH02, 1971TH08) and the discussion in ^{5}He. For polarization measurements see ^{9}Be. See also (1965LE12, 1967BE13, 1967BI1D, 1967FL12, 1967WI1C, 1969CO1F, 1971HU1H).
Deuteron groups are observed to ^{8}Be*(0, 2.9, 16.6, 16.9, 17.6). The group to ^{8}Be*(2.9) is well fitted by E_{x} = 2.82 MeV, Γ = 1.27 MeV (1971PI06). See also reaction 13 (1969NU01). The J^{π} = 1^{+} mixed isospin state have E_{x} = 16.627 ± 0.005 and 16.901 ± 0.005 MeV and Γ = 113 ± 3 and 77 ± 3 keV (1967MA12): see also Table 8.5 (in PDF or PS) and (1971PI06). Angular distributions have been measured at E(^{3}He) = 0.90 and 1.10 MeV (1971ST35; d_{0}), 3 MeV (1972LI31; d_{0}, d_{1}), and at 10 MeV by (1970DI12, 1970DI1F; d_{0}, d_{1}) and by (1968CO07; d to ^{8}Be*(16.6, 16.9)). Spindependent effects in the angular distributions of d_{0} and d_{1} obtained by (1963WE1B) at 24.3 MeV are discussed by (1967SI1A). The angular distribution to ^{8}Be*(16.6) is forward peaked, that for ^{8}Be*(16.9) is roughly isotropic (1968CO07). See also (1964MA57). The decay of various ^{9}Be states to ^{8}Be*(0, 2.9) has been studied by (1966CH20, 1968CO08, 1972MC1E): see ^{9}Be and Table 9.5 (in PDF or PS). See also (1968LI1D, 1970LI1Q) and (1967CO1L; theor.).
The angular distributions of the t_{0} group have been measured at many energies up to 48 MeV: see (1966LA04). Recently, measurements have been carried out at E_{α} = 23.2 and 25.0 MeV (1972VA34; t_{0}, t_{1}), 30 MeV (1972ME07; t_{0}, t_{1}; PWBAE and DWBA analysis) and at 50 MeV (1970LA14; t_{0}). The ground state of ^{8}Be does decay isotropically in the c.m. system and therefore J^{π} = 0^{+} (1970LA14). Spindependent effects in the angular distributions for t_{0} and t_{1} obtained by (1963WE1B: E_{α} = 28 MeV) are discussed by (1967SI1A). At E_{α} = 10 MeV an anomaly ("ghost") is observed in the ^{8}Be excitation spectrum at E_{x} ≈ 0.5 MeV. It may be due to interference of the 0^{+} states ^{8}Be*(0, 6.) [see reaction 4] or to thresholds of particle channels (1971BE52). In reaction (b), sequential decay is observed at E_{α} = 50 MeV, via ^{8}Be*(0, 2.9, 11.4, 16.6, 16.9, 19.9) (1970LA14). See also (1968BE1Q, 1968MA25).
At E(^{7}Li) = 1.4, 1.7 and 1.8 MeV, the angular distributions of ^{6}He ions leaving ^{8}Be in its ground and 2.9 MeV states are essentially isotropic (1968ST12). See also (1966LA04).
At thermal energies, the (n, p) cross section is (4.8 ± 0.9) × 10^{4} b (1955HA34, 1973MU14), the (n, α) cross section is ≤ 0.1 mb (1962BA1B, 1963BA34) and the (n, γα) cross section is 155 mb (1963BA34). These values, and comparison of the (p, n) cross section with that of reaction (a), support the J^{π} = 3/2^{} assignment for ^{7}Be(0) (1957NE22, 1963BA34). The role of these reactions in astrophysical phenomena is discussed by (1968FOZY, 1969BA1N). See also (1959AJ76) and reaction 17.
For E_{d} = 0.8 to 1.7 MeV, proton groups are observing corresponding to the ground state and ^{8}Be*(2.9): derived parameters for the latter are shown in Table 8.4 (in PDF or PS) (1959SP1A, 1960KA17). See also (1969BA43; theor.).
^{8}Li decays mainly to the broad 2.9 MeV, 2^{+} level of ^{8}Be, which decays into two αparticles. Both the βspectrum and the resulting αspectrum have been extensively studied. There appears to be an increasing excess of αparticles with E_{α} which may reflect transitions into the tail of the J^{π} = 2^{+} level at E_{x} = 16.67 MeV. See (1959AJ76, 1966LA04) for earlier references. See also (1969KL08) and ^{8}B(β^{+}). Studies of the distribution of recoil momenta and neutrino recoil correlation indicate that the decay is overwhelmingly GT, axial vector [see reaction 1 in ^{8}Li] and that the ground state of ^{8}Li has J^{π} = 2^{+}: see (1966LA04). Angular correlations have been measured for the decays of ^{8}Li and ^{8}B as a test of the conserved vector current theory of βdecay. The values of the coefficients are displayed in Table 8.10 (in PDF or PS). See also (1973TR1J, 1973TR1K, 1973TR1L). The experimental value of δ [δ ≡ B(^{8}Li)  B(^{8}B)] is (5.4 ± 0.4)W_{β}, consistent with CVC theory (1966EI02). A recent asymmetry measurement is reported by (1971VA19). See also (1971VA1E, 1973NE10). Measurements of the excitation spectra in the decays of ^{8}Li and ^{8}B show no evidence for second class currents: g_{IT} < 7 × 10^{4} (1971WI05). See also (1966JA1C) and (1960KU05, 1960WE1A, 1966BA26, 1966LI1C, 1968KR10, 1969BA43, 1970DA21, 1971LI1H, 1971WI18, 1971WI1C, 1972EM02, 1972HO23, 1972MI1M, 1972WI28, 1972WI1C, 1973EM1B, 1973HA49, 1973TO14, 1973WI11, 1974WI1L; theor.).
The decay proceeds mainly to ^{8}Be*(2.9) [see Table 8.4 (in PDF or PS) for its parameters]. Detailed study of the high energy portion of the αspectrum reveals a maximum near E_{α} = 8.3 MeV, corresponding to transitions to ^{8}Be*(16.63), for which parameters E_{x} = 16.67 MeV, Γ = 150 to 190 keV or E_{x} = 16.62 MeV, Γ = 95 keV are derived. Using τ_{1/2} = 769 ± 4 msec, log ft = 2.9. The low ft value supports the identification J^{π} = 2^{+}; T = 1 for ^{8}Be*(16.63) (1964MA35). See, however, (1965MA1G). The energy distribution of αparticles has also been measured by (1969CL10). Analysis of this data and of data from α  α scattering in a three level Rmatrix formalism indicate a 2^{+} state of ^{8}Be at E_{x} = 12.0^{3.0}_{+3.5} MeV and of Γ = 14^{3}_{+4} MeV (a_{2} = 6.0 ± 0.5 fm) (1969CL10). See also (1969BA43; theor.). For angular correlation measurements see reaction 28 (1966EI02) and Table 8.10 (in PDF or PS). See also (1973TR1J, 1973TR1K, 1973TR1L).
For reaction (a) see (1966DE07, 1968AD09, 1969GA1M) and (1965BO1B, 1969AU05; theor.). See also ^{9}Be. Reaction (b) appears to proceed largely via excited states of ^{9}Be, with subsequent decay to ^{8}Be, mainly ^{8}Be*(2.9): see (1966LA04), ^{9}Be and ^{10}Be. At E_{n} = 14 MeV the cross section at 20° for production of dineutrons is < 2 mb/sr (1966RO1G). See also (1965GO1C, 1965GO1E, 1966BO1C, 1966BO1F, 1966FE1C, 1967BO1F, 1969PR13). For reaction (c) see (1966NO1A; theor.) and ^{9}Be. For reaction (d) see (1967SE11). For reaction (e) see (1971GU15, 1973GE1J) and ^{9}Be.
Angular distributions of deuteron groups have been reported at E_{p} = 0.11 to 0.55 MeV (1973SI27; d_{0}), 0.30 to 0.90 MeV (1968BE1N; d_{0}), 5 to 11 MeV (1972HU03; d_{0}) [analysis by DWBA and BHMM (1967BU23); derived spectroscopic factors], 13.0, 14.0, 15.0 and 21.35 MeV (1972VO1H; d_{0}), 17.0, 21.0, 25.0, 29.1 MeV (1973MO01; d_{0}, d_{1}), 33.6 MeV (1967KU10, 1970KU1D: deuterons to ^{8}Be*(0, 2.9, 16.95, 17.62, 18.18, 19.21); also derived spectroscopic factors) [also saw ^{8}Be*(11.4); determined Γ_{c.m.}(16.95) = 103 ± 15 keV, Γ_{c.m.}(19.21) = 208 ± 30 keV], 40.8 MeV (1966MA22: deuterons to ^{8}Be*(16.63, 16.91)), 46 MeV (1967VE01: deuterons to ^{8}Be*(0, 2.9, 16.9, 17.6, 18.2, 19.1) [also report ^{8}Be*(24.5)], 100 MeV (1968LE01: deuterons to ^{8}Be*(0, 2.9, 16.9, 18.9)) [also saw ^{8}Be*(11.0, 23.0, 26.0)], 155 MeV (1969BA05, 1969TO1A: deuterons to ^{8}Be*(0, 2.9) [Γ = 2.0 ± 0.1 MeV], 11.5 [Γ = 8 ± 1 MeV], 16.8 ± 0.2, 18.9 ± 0.3) [also saw ^{8}Be*(17.6 ± 0.4, 21.5 ± 0.3)] and 185 MeV (1969SU02: deuterons to ^{8}Be*(0, 2.94 ± 0.08, 11.3 ± 0.3, 16.87 ± 0.06, 17.58 ± 0.08, 18.10 ± 0.10, 19.16 ± 0.07, 22.0 ± 0.15, 22.9 ± 0.15)) [also report ^{8}Be*(20.0 ± 0.2 (?)); Γ_{c.m.}(2.9) = 1.5 ± 0.1 MeV; Γ_{c.m.}(22.0, 22.9) ≥ 1 MeV (the angular distributions for these two states are not clear cut)]. (1971SC26) have analyzed the angular distributions obtained by (1967VE01, 1968LE01) using DWBA with a localenergy approximation and have derived spectroscopic factors. With the exception of ^{8}Be*(11.4, 22.0, 22.9) the angular distributions are consistent with l = 1. The yield of the deuterons corresponding to ^{8}Be*(16.63) is very low: [≈ 5% compared to ^{8}Be*(16.91)] as expected by predictions of the cluster model (1966MA22: E_{p} = 40.8 MeV). See also (1967KU10) and reaction 21 in ^{9}Be in (1966LA04). Anomalies in the deuteron spectrum between the d_{0} and the d_{1} groups have been reported at various energies [see (1966LA04) and (1967FI1D, 1967HA1K, 1971BE52, 1971MI1C)]. The shape of the deuteron spectrum near ^{8}Be*(2.9) requires a_{2} ≈ 7.1 fm (1969BA43). See also reaction 4 and (1968BA2D). At E_{p} = 17 MeV, for the transitions to ^{8}Be*(0, 2.9) the ratios of σ(p, d)/σ(p, d) = 11.8 and 14.1, respectively (1967CO09, 1969CO06). See also (1968NA1A; theor.). Reaction (b) at E_{p} = 9 MeV is dominated by strong final state interactions through ^{8}Be*(0, 2.9) and ^{6}Li*(2.19) with little or no yield from a direct threebody decay (1971EM01). See also (1967FI1D). See also ^{10}B and (1966CA1E, 1966LA20, 1967OG1A, 1967RO07, 1968TI1A, 1972QU01) and (1967BA1M, 1967JO1D, 1968BO1P, 1970BO1K; theor.).
At E_{d} = 11.8 MeV, angular distributions have been obtained for the tritons to ^{8}Be*(0, 2.9) (1967FI07): S = 0.51 and 0.75, respectively (DWBA analysis). At E_{d} = 38 MeV, angular distributions of the tritons to ^{8}Be*(16.91, 17.64, 19.0) have been compared with those of the ^{3}He to the analog states in ^{8}Li. The crosssection ratios σ_{17.64}/σ_{0.98(8Li)} = 0.45 ± 0.04 and σ_{16.91}/σ_{0(8Li)} = 0.75 ± 0.04, consistent with the pure T = 1 nature of ^{8}Be*(17.64) and the mixed T nature of ^{8}Be*(16.91) [and ^{8}Be*(16.63)] (1966GA21; abstract). Angular distributions have also been measured at E_{d} = 0.3 to 1.0 MeV (1968BE1E; t_{0}), 0.9 to 3.1 MeV (1973SA1Q; t_{0}), 15.0 MeV (1969AR1B; t_{0}) and at many other energies up to E_{d} = 20 MeV: see (1966LA04). The ghost anomaly which is seen near the t_{0} group has been studied at E_{d} = 2.5 MeV: it is interpreted as being due to an extreme threshold effect (1971BE52). See also (1967DE1J) and (1970BO1K, 1973HE1J; theor.). A kinematically complete study of reaction (b) at E_{d} = 26.3 MeV indicates the involvement of ^{8}Be*(0, 2.9, 11.4, 16.9, 19.9 + 20.1). Parameters obtained for ^{8}Be*(2.9, 11.4) are E_{x} = 3.20 ± 0.03 and 11.70 ± 0.07 MeV, Γ = 1.72 ± 0.09 and 4.41 ± 0.5 MeV (1973SO08).
Angular distributions have been measured at E(^{3}He) = 3.0 MeV (1968MO05; α_{16.91}), 3.0 and 4.0 MeV (1963DO08; α_{0}, α_{2.9}, α_{16.6}, α_{16.9}, α_{17.6}), 18.0, 22.7, 26.7, 32.3 MeV (1965AR07; α_{0}, α_{1}) and 26.7 MeV (1968AR12; α_{16.9}, α_{17.6}, α_{18.1}, α_{19.2}). See also (1959AJ76) and (1967SI1A). The parameters of the observed states are shown in Tables 8.4 (in PDF or PS) and 8.5 (in PDF or PS) (1961ER01, 1963DO08). Reaction (b) has been studied at E(^{3}He) = 1.6 MeV (1970EH1A), 3.0 MeV (1966SU04, 1968MO05) and 3.0 and 4.0 MeV (1972TA04). See also (1966LA04) and (1967ST1E). The reaction proceeds by sequential decay via ^{8}Be*(0, 2.9, 11.4, 16.6, 16.9, 19.9, 22.5) (1972TA04). The angular correlation via ^{8}Be*(16.91) is consistent with J^{π} = 2^{+} for that state (1968MO05). J^{π} = 2^{+} is also indicated for ^{8}Be*(16.63) (1966SU04). See also (1968TH1G). For reaction (c) see (1967ST1D). See also (1964MA57, 1966CA08, 1966DI1C, 1967OG1A, 1970CA28, 1971TR1B, 1972RO1N), (1967HO1C) and (1970BO1K, 1971OS05, 1972TH04, 1973RO28; theor.).
At E(^{6}Li) = 3.5 MeV the population of ^{8}Be*(2.9) is very small but ^{8}Be_{g.s.} is involved (1968JA08). See also (1966LA04). For reaction (b) see (1966LE10) and (1968TO1C; theor.). For reaction (c) see (1970BA1J, 1970BA1Y). For reaction (d) see (1968KN1A, 1970BA1J, 1970BA1Y). Reaction (e) has been studied at E(^{18}O) = 16 and 20 MeV (1971KN05). See also (1968FA04). For reaction (f) see (1968FA04).
Angular distributions have been measured at E_{n} = 14.4 MeV (1964VA14; t_{0}, t_{1}). Reaction (b) has been studied at the same energy by (1967VA12). See also (1971MI1H) and (1967BA1E; theor.). See also ^{11}B in (1975AJ02).
At E_{p} = 49.5 MeV angular distribution measurements have been carried out for the ^{3}He groups to ^{8}Be*(0, 2.9, 16.6, 16.9): the ratio dσ(16.63)/dσ(16.91) has a mean value of 0.65 ± 0.05 for θ = 15° to 30°, suggesting possibly a preferential excitation of the T = 1 components of these two states. The ratio of the differential cross sections dσ(p, t) [to ^{8}B_{g.s.}] to dσ(p, ^{3}He) [to ^{8}Be*(16.63, 16.91)] (15° to 30°) seems to also suggest this (1971SQ01).
Angular distributions have been reported at E_{d} = 0.5 to 1.0 MeV (1968FR07; α_{0}, α_{1}), 0.8 to 2.5 MeV (1968CO31; α_{0}, α_{1}), 3.0 to 7.2 MeV (1967LE1C; α_{0}) and 7.5 MeV (1966BR08; α to ^{8}Be*(16.63, 16.91, 17.64, 18.15)). At E_{d} = 7.5 MeV the total cross section for formation of ^{8}Be*(16.63), σ_{t}(16.63), is about 1.15 σ_{t}(16.91), consistent with the mixed isospin character of these two states. σ_{t}(18.15) is ≈ 0.85 σ_{t}(16.91), but the other nearby 1^{+} state ^{8}Be*(17.64) has σ_{t}(17.64) ≈ 0.07 σ_{t}(16.91), consistent with the nearly pure T = 1 nature of ^{8}Be*(17.64) (1966BR08). These four states [^{8}Be*(16.63, 16.91, 17.64, 18.15)] have been studied for E_{d} = 4.0 to 12.0 MeV. Interference between the 2^{+} states [^{8}Be*(16.63, 16.91)] varies as a function of energy. The cross section ratios for formation of ^{8}Be*(17.64, 18.15) vary in a way consistent with a change in the population of the T = 1 part of the wave function over the energy range: at the higher energies, there is very little isospin violation. At higher E_{x} only the 3^{+} state at E_{x} = 19.2 MeV is observed, the neighboring 3^{+} state at E_{x} = 19.06 MeV is not seen. The J^{π} = 1^{+}; T = 0 state is found to have E_{x} = 18.146 ± 0.005 MeV (based on 17.638 for the J^{π} = 1^{+}; T = 1 state) and Γ = 138 ± 6 keV (1970CA12). There is some question as to whether a twolevel fit can be made for the α groups to ^{8}Be*(16.63, 16.91). ((1970CA12) and W.D. Callender, private communication) are dubious about this, feeling that other 2^{+} states have to be brought into the calculation. Based on a twolevel fit they find the following average values: Γ_{16.6} = 113 keV, Γ_{16.9} = 80 keV, ΔQ = 302 keV. However, (1971NO04) state that the twolevel fit is appropriate if the spectra are properly corrected for effects of final state Coulomb interactions: Γ_{16.6} = 90 ± 5 keV, Γ_{16.9} = 70 ± 5 keV, ΔQ = 290 ± 7 keV. See also (1966BR22) and (1970KI1D; theor.). For a listing of the parameters of observed states see Tables 8.4 (in PDF or PS) and 8.5 (in PDF or PS) (1961ER01, 1969NU01, 1970CA12). Angular correlation studies [E_{d} ≤ 3 MeV] indicate that reaction (b) takes place mainly by a sequential process involving ^{8}Be*(0, 2.9, 11.4, 16.6, 16.9): see (1968LO01, 1970ST02, 1971LA14) and (1967CA13, 1968AS01). (1968LO01) report E_{x} = 2.7 ± 0.2 MeV, Γ = 1.0 ± 0.1 MeV, and Γ = 3.0 ± 0.5 MeV for ^{8}Be*(11.4). See also (1967CA13, 1970ST02). For a study of rescattering effects see (1972VA1L). See also ^{12}C and (1964MA57, 1965PA1E, 1966AS10, 1966DI1C, 1967AS1A, 1967NA11, 1967PE1B, 1968TH1G, 1969NA17, 1972RO1N), (1966BR1G) and (1967BA1M, 1968NA1B, 1970KO01, 1970NA06, 1973RO28; theor.).
At E(^{3}He) = 2.45 and 6.00 MeV this reaction proceeds primarily by sequential decay via ^{8}Be*(0, 2.9) and via ^{5}Li, ^{9}B and ^{12}C states [see also the latter nuclei] (1966WA16). See also (1966WI08, 1968KR02, 1970BE1F), (1966LA04, 1967HO1C) and (1967PR1B; theor.).
At E_{α} = 46 MeV angular distributions obtained for the transitions to ^{8}Be*(0, 2.9) are consistent with a direct interaction mechanism (1970ZE03).
See ^{11}B in (1975AJ02).
Angular distributions have been measured at E_{p} = 0.78 to 12.00 MeV (1963SY01, 1968WA1G; α_{0}), 1.4, 2.0 and 2.6 MeV (1972GE19; α_{0}, α_{1} (not at 2.0)), 12, 20, 24 and 30 MeV (1971CA16; α_{0}), 26.7 and 38 MeV (1969GA03, 1970GU06; α_{0}), 40 MeV (1971KA21; α_{0}, α_{1} and α to ^{8}Be*(12.5) [Γ = 4.0 ± 0.5 MeV] and to ^{8}Be*(16.6 + 16.9, 17.6, 18.1, 19.0)) and at E_{p} = 45 MeV (1971DE2B, 1972DE01, 1972DE02; α_{0}, α_{1}). At E_{p} = 45 MeV the angular distributions are typical of a direct reaction mechanism, with a rise in the backward direction indicative of heavy particle stripping (1972DE01, 1972DE02). Observed parameters for ^{8}Be*(2.9) are shown in Table 8.4 (in PDF or PS) (1969NU01, 1971KA21). At E_{p} = 40 MeV, θ = 20°, dσ_{16.6}/dσ_{16.9} = 2.3 ± 0.4 (1971KA21). Reaction (b) has been studied for E_{p} = 0.15 to 9.5 MeV. The reaction proceeds predominantly by sequential twobody decay via ^{8}Be*(0, 2.9): see, e.g., (1965BR18, 1968CH01, 1972HU04). See also (1967KA09, 1967MA11, 1968GI03, 1969QU01, 1970CO03, 1971KO22, 1972MI1J). Some papers report very narrow widths in this reaction for ^{8}Be*(2.9). However, (1972HU04) find a good fit to the data with E_{x} = 2.99 MeV, Γ = 1.45 MeV when an interference term is included. The interference effect is attributable to the identity of the three αparticles and to the ambiguity in their order of emission (1965BR18). See also ^{12}C in (1968AJ02, 1975AJ02), (1966LA04), (1966LO1G, 1967CO29, 1967EN1A, 1967FL12, 1967TR1B, 1968LA1C, 1969LA1B, 1969TR1D, 1972DZ10, 1973PR1C), (1969PH1B) and (1969GO13, 1970GO1J, 1970GO33, 1970GO49, 1970KO1K, 1970MC25, 1970MC1T, 1970SC01, 1972TH1M, 1973DU1D, 1973GO35; theor.).
This reaction has been studied for E(^{3}He) = 1.4 to 5.8 MeV. Angular distributions have been measured at E(^{3}He) = 5.2 MeV involving ^{8}Be_{g.s.} + ^{6}Li_{g.s.}, ^{8}Be_{g.s.} + ^{6}Li^{*}_{3.56}, and ^{8}Be^{*}_{2.9} + ^{6}Li_{g.s.} (1967YO02, 1967YO1C, 1968ME13).
Angular distributions have been reported at E_{α} = 28.4 and 29.0 MeV for ^{8}Be_{g.s.} + ^{7}Li_{g.s.}, ^{8}Be_{g.s.} + ^{7}Li^{*}_{0.48} and ^{8}Be^{*}_{2.9} + ^{7}Li (29 MeV only) by (1968KA24) and at 42 MeV for ^{8}Be_{g.s.} + ^{7}Li_{g.s.} and ^{8}Be_{g.s.} + ^{7}Li^{*}_{0.48} by (1968MI05). At E_{α} = 65 MeV ^{8}Be*(16.6 + 16.9, 20.0) are apparently also excited (1973WO06). See also (1966GE12) and ^{7}Li. For reaction (b) see (1969FU09).
For reaction (a) see (1966LA04), (1973CL1E) and (1965DZ1A; theor.). For reaction (b) see (1970EN1A).
This reaction proceeds via ^{8}Be*(0, 2.9) at E_{n} = 13 to 18 MeV, and via states in ^{5}He, ^{9}Be and ^{12}C (1966MO05). See also (1966LA04) and (1971DO1K).
This reaction has been studied for 13 ≤ E_{p} ≤ 160 MeV. At low energies it involves ^{8}Be(0); at higher energies ^{8}Be*(0, 2.9) (1966RO1D, 1967GA01, 1969LU1B, 1970GO12, 1970KE1B, 1972MA62). It is not clear whether higher states are also involved: see (1970KE1B). See also (1966LA04) and (1966JA1B, 1968YA1C, 1972YA1B).
Angular distributions have been determined at E_{d} = 19.5 MeV (1971GU07), 28 MeV (1972BE1T, 1972BE29: ^{8}Be(0)) and 51.8 MeV (1970EI05: both ^{8}Be*(0, 2.9)). At E_{d} = 28 MeV a structure is observed which is attributed to the process ^{12}C(d, α)^{10}B → α + ^{6}Li (1972CO23). At E_{d} = 55 MeV the population of ^{8}Be*(11.4, 16.6 + 16.9) is also reported (1971MC04). See also (1966DA1C, 1970AN1E), (1967OG1A, 1972GA1E) and (1968RO1D, 1970EL1F, 1971DR02, 1973HE1J; theor.). See also ^{12}C and (1966LA04).
Angular distributions have been measured for the transitions to ^{7}Be_{g.s.} + ^{8}Be_{g.s.} and ^{7}Be^{*}_{0.43} + ^{8}Be_{g.s.} at E(^{3}He) = 25.5 to 29 MeV (1972PI1A, 1973PI1B, 1973PI1D), 28 MeV (1970DE12, 1973KL1B) and at 35.7 MeV (1969ZE1A, 1970FO1D). The transitions to ^{7}Be_{g.s.+0.43} + ^{8}Be^{*}_{2.9} have also been studied by (1970DE12). See also (1967ZA1B, 1973ST1N) and (1969NE1D; theor.).
This reaction has been studied up to E_{α} = 104 MeV. At E_{α} = 25 MeV it involves ^{8}Be(0) (1966BO28); at E_{α} = 28.0, 37.4, 70, 90 and 104 MeV, the reaction goes via ^{8}Be*(0, 2.9) (1965YA02, 1967TA1C, 1968YA02, 1971BR1G, 1972SH1J) and at 90 MeV it may, in addition, involve the broad 4^{+} state at 11.4 MeV (1970JA06). See also (1966LA04) and (1965KU1B, 1967ME1C; theor.). Reaction (b) has been studied for 11.9 ≤ E_{α} ≤ 19.4 MeV and angular distributions are reported for E_{α} = 12.70 to 16.25 MeV (1967CH21) and 65 MeV (1973WO06: ^{8}Be*(0, 2.9)). See ^{16}O in (1971AJ02).
Angular distributions have been measured for E(^{12}C) = 11.6 to 13.4 MeV (1972CO1H). At E(^{12}C) = 50 to 65 MeV the population of ^{8}Be*(0, 2.9) is reported by (1972FL1C). See also (1968JA1F, 1970JA1B, 1972GR1T, 1973CR1A, 1973SC1J).
See (1965WI1A).
See (1972GR1Q).
Angular distributions have been measured at E_{p} = 45 MeV for the transitions to ^{8}Be*(0, 2.9) (1971BR07).
Angular distributions are reported at E_{d} = 14.6 MeV for the transitions to ^{8}Be_{g.s.} + ^{7}Li_{g.s.} and ^{8}Be_{g.s.} + ^{7}Li^{*}_{0.48} (1967DE03).
Angular distributions have been obtained at E(^{3}He) = 3.3, 5.0 and 5.8 MeV for the transition to ^{8}Be_{g.s.} + ^{8}Be_{g.s.} (1968JA07, 1969JA1L). See also ^{16}O in (1971AJ02) and (1967SA1E).
See (1967MO21, 1971SC16) and ^{7}Li.
See (1966LA04) and ^{12}C in (1968AJ02).
See (1961KO02, 1962VA1A) and ^{16}O in (1971AJ02).
Angular distributions have been measured at E_{α} = 65 MeV involving ^{8}Be_{g.s.} and ^{12}C*(0, 4.4) (1973WO06). See also (1968PA12) and ^{16}O in (1971AJ02) and ^{20}Ne in (1972AJ02).
See (1965SH11).
See (1969GO1B, 1971GO1U) and ^{20}Ne in (1972AJ02).
This reaction has not been observed: see (1962LA15).
