
^{7}Li (2002TI10)(See Energy Level Diagrams for ^{7}Li) GENERAL: References to articles on general properties of ^{7}Li published since the previous review (1988AJ01) are grouped into categories and listed, along with brief descriptions of each item, in the General Tables for ^{7}Li located on our website at (nucldata.tunl.duke.edu/NuclData/General_Tables/7li.shtml). See also 3 [Electromagnetic Transitions in A = 57] (in PDF or PS) and 7.2 [Table of Energy Levels] (in PDF or PS).
Q = 40.6 ± 0.8 mb (1988DI1B). See (1988DI1B) for a review of earlier determinations, particularly those of (1984SU09, 1984VE03, 1984VE08, 1985WE08). See also (1989RA17). B(E2): 3/2^{} → 1/2^{} = 8.3 ± 0.5 e^{2}fm^{4} (1985WE08). See also (1984VE08), (1988TA1D) and (1984AJ01). Isotopic abundance: 92.5 ± 0.2% (1984DE53). See also (1987LA1J, 1988LA1C). The interaction nuclear radius of ^{7}Li is 2.23 ± 0.02 fm (1985TA18). [See also for derived nuclear matter, charge and neutron matter r.m.s. radii].
Gamma spectra were measured for 40 MeV/A ^{6}He incident on a solid hydrogen target (2001SA37). The ^{7}Li ground state and the 0.48 MeV first excited states were not resolved. Measurements of momentum spectra of fragments as well as gammaray intensity distributions are described in (2001SA37). See also (2001SAZS).
Excitation functions and angular distributions have been studied for E_{α} = 0.5 to 2.0 MeV. The cross section rises smoothly as expected for a direct capture process: see (1966LA04) and (1987BU18; γ_{0}, γ_{1}). Measurements of the astrophysical Sfactor, S(E), and the branching ratio R for direct capture to the 478 keV state compared to direct capture to the ground state were reported by (1987SC18). They deduce S(0) = 0.14 ± 0.02 keV b, R = 0.32 ± 0.01. More recently, available data on ^{3}H + α scattering were analyzed (1993MO11) in the optical model framework to predict S(0) = 0.10 keV b and branching ratio R = 0.43. Measurements of the cross sections and angular distributions in the energy range 50 ≤ E ≤ 1200 keV were reported by (1994BR25). They determined R ≈ 0.45 at low energies in disagreement with (1987SC18). An extended twocluster model study for E_{cm} < 5 MeV is described in (2000CS06). Effects of inclusion of the ^{6}Li + n channel on the zeroenergy cross section and astrophsyical S factor as well as the quadrupole moment are explored. A recent analysis by (1999BU10) estimated the uncertainties in Big Bang nucleosynthesis ^{7}Li yields. For astrophysical calculations related to ^{3}H(α, γ) see the General Table for ^{7}Li located on our website at (nucldata.tunl.duke.edu/NuclData/General_Tables/7li.shtml). See also references cited in (1988AJ01). Thermonuclear reaction rates for this reaction calculated from evaluated data are presented in the compilation (1999AN35).
The cross section for this reaction has been measured for E_{α} = 11 to 18 MeV: the data show the effect of ^{7}Li*(7.46) and indicate a broad resonance near E_{α} = 16.8 MeV [^{7}Li*(9.6)]. The level parameters derived from this reaction and from reaction 4 are displayed in 7.3 (in PDF or PS). The yield of ^{6}Li ions at 0° (lab) has also been measured for E_{α} = 11.310 to 11.930 MeV with 2  3% accuracy: the data were then reduced to obtain the cm differential cross sections at 0° and 180° for the inverse reaction in the energy region corresponding to formation of ^{7}Li*(7.46): see (1979AJ01). See also the compilation of (1985CA41). A resonating group calculation of σ(E) from threshold to 20 MeV is reported in (1991FU02).
The excitation curves for the elastic scattering show the effects of ^{7}Li*(4.63, 6.68, 7.46, 9.67). The derived level parameters are displayed in 7.3 (in PDF or PS). Angular distributions have been studied for E_{α} = 2.13 to 2.98 MeV and E_{t} = 6.0 to 17 MeV [see (1979AJ01, 1984AJ01)] and at E_{α} = 56.3 to 95.5 MeV (1986YA1M; also A_{y}]. More recently, cross sections and angular distributions were measured at E_{α} = 27.2 MeV and described in an RGM method and in the phenomenological optical model. A polarization extremum (A_{y} = 1) occurs near E_{t} = 11.1 MeV, θ = 95°: see (1984AJ01). For the breakup of ^{7}Li into α + t in various processes see (1984AJ01) and (1984SH17, 1987FO08, 1987PO03) as well as the General Table for ^{7}Li located on our website at (nucldata.tunl.duke.edu/NuclData/General_Tables/7li.shtml). For cross sections determined from shellmodel and Rmatrix calculations see (1987KN04). Other calculations that have been reported include: phase shifts for E_{α} < 300 MeV and ^{7}Li charge form factor (1987RO24); scattering lengths (1988CH47, 1989CH34); phaseshift and transmission coefficients with RGM (1991FU02); phaseshift and astrophysical S factors in a twocluster model (1995DU09, 1997DU15); RGM phase shifts (1995MA37); and phase shifts versus E in a threebody cluster model (1996SH02). For muon catalysis see references cited in (1988AJ01).
^{7}Li*(0 + 0.48, 4.63) have been populated at E(^{3}He) = 266.5 and 280.5 MeV: see (1984AJ01). See also (1984GE05, 1987KA09).
Angular distributions have been reported at E_{α} = 39.9 to 140 MeV [see (1979AJ01, 1984AJ01)] and at 61.5 to 158.2 MeV (1982GL01) and 198.4 MeV (1985WO11) for the transitions to ^{7}Li*(0, 0.48). Cross sections for E_{α} = 159.3, 279.6 and 619.8 MeV were measured by (2001ME13) to enable calculation of the amount of ^{7}Li produced in earlygalaxy cosmic rays. See also (2001AU06). See (1982GL01, 1985WO11) for a discussion of ^{7}Li production in the Big Bang. See also ^{8}Be in (1988AJ01) and (1986KA26).
The thermal capture cross section is 38.5 ± 3.0 mb (1981MUZQ). Gamma rays are observed corresponding to transitions to ^{7}Li*(0, 0.48) with branching ratios 62 ± 2% and 38 ± 2% (1985KO47). ^{7}Li*(4.63, 6.68) are not populated [≤ 5%] (1985KO47). See (1979AJ01) for the earlier work. The decay of ^{7}Li*(7.46) → ^{6}Li_{g.s.} + n in the interaction of 35 MeV/A ^{14}N ions on Ag is reported by (1987BL13). A recent study discussed in (1997NO04) analyzed reaction rates of ^{6}Li(n, γ) and other reactions that bear on the possibility of observing primordial ^{6}Li.
The real coherent scattering length is 2.0 ± 0.1 fm; the complex scattering lengths are b_{+} = (0.67 ± 0.14)  i(0.08 ± 0.01) fm, b_{} = (4.67 ± 0.17)  i(0.62 ± 0.02) fm; σ_{free} = 0.70 ± 0.01 b (1983KO17). See also (1979GL12). (1983AL1E) report σ_{s} (below 10 keV) = 0.72 ± 0.02 b. See also (1981MUZQ). The total cross section has been measured from E_{n} = 4 eV to 49.6 MeV [see (1976GAYV, 1984AJ01)], at 0.6 to 80 keV (1982AL35) and at 0.08 to 3.0 MeV (1983KN1D). A pronounced resonance occurs at E_{n} = 244.5 ± 1.0 keV [E_{x} = 7459.5 ± 1.0 keV] with a peak cross section of 11.2 ± 0.2 b (1982SM02): see 7.4 (in PDF or PS). No other clearly defined resonance is observed to E_{n} = 49.6 MeV although the total cross section exhibits a broad maximum at E_{n} ≈ 4.5 MeV: see (1984AJ01). The analyzing power has been measured for E_{n} = 1.48 to 5 MeV [see (1984AJ01)] and 5 to 17 MeV (1986PF1A). Multilevel, multichannel Rmatrix analyses (1987KN04, 1983KN06) for E_{n} ≤ 8 MeV [using also data from other channels] include 13 normal and 14 nonnormal parity states with E_{x} ≤ 17 MeV. [Only ten states have been seen directly in reaction or compound nucleus crosssection work.] Two positiveparity states provide an explanation for the anisotropy of the ^{6}Li(n, α) work at low energies (1983KN06). For the results of an earlier Rmatrix analysis see (1984AJ01). The excitation function for 3.56 MeV γrays exhibits an anomaly, also seen in the (n, p) reaction (reaction 9). The data are well fitted assuming E_{res} = 3.50 and 4.60 MeV [E_{x} = 10.25 ± 0.10 and 11.19 ± 0.05 MeV], T = 1/2 and 3/2, Γ_{cm} = 1.40 ± 0.10 and 0.27 ± 0.05 MeV, respectively; both J^{π} = 3/2^{}. However, (1979AJ01) notes that an Rmatrix study of ^{4}He(t, t), ^{6}Li(n, n), and ^{6}Li(n, α) data leads to the identification of a 3/2^{} state at E_{x} = 9.85 MeV, Γ = 1.2 MeV. See (1979AJ01) for a discussion of these and other unpublished data. Differential cross sections for n_{0} and n_{1} were measured at E_{n} = 6.8  9.8 MeV and used with other data in an analysis to deduce σ(E) for E_{n} = 6  14 MeV (1987SC08). Elastic and inelastic scattering cross sections σ(θ) were measured for E_{n} = 24 MeV (1987HA25) and analyzed, along with existing proton scattering data to study neutron and proton transition densities. Elastic and inelastic scattering differential cross sections were measured at E_{n} = 11.5, 14.1 and 18.0 MeV (1998CH33) and used to determine a phenomenological optical model potential. A measurement of doubledifferential neutron emission cross sections for E_{n} = 11.5 and 18.0 MeV was reported by (1998IB02). Theoretical work includes: a calculation of coherent and incoherent thermal cross sections (1990GO26); RGM calculations of σ(θ) at E_{n} = 18 MeV (1992KA06); calculation of phase shifts and cross sections for E_{n} < 18 MeV using a potential description (1993DU09); a study of antisymmetry contribution to the nucleonnucleon potentials (1995CO18); and a study of the applicability of opticalmodel potentials for nuclear data evaluations (1996CH33). See also earlier references cited in (1988AJ01).
For reaction (a) see (1985CH37, 1986CH24). The excitation function for reaction (b), measured from threshold to E_{n} = 8.9 MeV, exhibits an anomaly at E_{n} = 4.6 MeV. The excitation function, at forward angles, of p_{0} is approximately constant for E_{n} = 4.4 to 7.25 MeV: see (1979AJ01). Measurements of particle spectra have been made at E_{n} = 198 MeV (1987HE22), E_{n} = 118 MeV (1987PO18, 1988HA12, 1998HA24). Studies of this reaction as a probe of GamowTeller strength are reported in (1988JA01, 1988WA24, 1992SO02). Measurements at E_{n} = 280 MeV were used in a test of isospin symmetry (1990MI10). Measurements at E_{n} = 0.88 GeV with polarized targets are reported in (1996BB27). Theoretical studies of this reaction include: a dynamical cluster model calculation for E_{n} = 280 MeV (1991DA08); a calculation of phase shifts for E_{n} = 6.77 MeV (1993DU09); a calculation with hyperspherical harmonics (1996DA31); and with a threebody cluster model for E_{n} = 50 MeV (1997DA01). See also (1997ER05, 1997VA06). The excitation function, at forward angles, of deuterons (reaction (c)) increases monotonically for E_{n} = 5.4 to 6.8 MeV: see (1979AJ01, 1988AJ01). A multiconfiguration resonatinggroup method calculation of σ(θ) for E_{n} = 12 MeV is described in (1995FU16).
The thermal cross section is 940 ± 4 b: see (1981MUZQ). See also (1985SW01). A resonance occurs at E_{n} = 241 ± 3 keV with σ_{max} = 3.3 b: see (1984AJ01, 1986CA28). The resonance is formed by pwaves, J^{π} = 5/2^{}, and has a large neutron width and a small αwidth: see 7.4 (in PDF or PS). Above the resonance the cross section decreases monotonically to E_{n} = 18.2 MeV, except for a small bump near E_{n} ≈ 1.8 MeV and an inflection near E_{n} = 3.5 MeV. For a description of Rmatrix analyses which suggest the location of higher states of ^{7}Li, see reaction 8 and (1984AJ01), as well as (1987KN04). Angular distributions have been measured at many energies in the range E_{n} = 0.1 to 14.1 MeV [see (1979AJ01, 1984AJ01)] as well as from 35 eV to 325 keV (1983KN03) and 2.16 to 4.20, 7.1 and 13.7 MeV (1986BA32, 1986BA68). Polarization measurements have been reported for E_{n} = 0.2 to 2.4 MeV: the data suggest interference between swaves and the pwave resonance at 0.25 MeV. Interference between this 5/2^{} state and a broad 3/2^{} state 2 MeV higher also appears to contribute. At the higher energies A_{y} is close to +0.9 near 90° and varies slowly with E_{n}: see (1979AJ01). See also (1983VE10, 1984VEZW). Measurements with polarized thermal neutrons for studying parity violation effects have been reported in (1990VE16, 1994GL07, 1996VE02). Reaction rates for E < 2 MeV were analyzed (1997NO04) in connection with the possibility of observing primordial ^{6}Li. Calculations of tritium production in applications of this reaction are described in (1993FA01). For a study of coincidences in the ^{6}Li(n, αd)n reaction see (1986MI11). The triton production cross section at E_{n} = 14.92 MeV is 32 ± 3 mb (1985GO18). The total αproduction cross section [which includes the (n, nd) process] at E_{n} = 14.95 MeV is 512 ± 26 mb (1986KN06). See also the references cited in (1988AJ01).
At E_{p} = 600 MeV, the reaction preferentially excites ^{7}Li*(4.63). Angular distributions have been obtained for the pions to ^{7}Li*(0, 0.48, 4.63) at E_{p} = 600 and 800 MeV. ^{7}Li*(11.24) [T = 3/2] is not observed: see (1984AJ01). Recently σ(θ) and A_{y} measurements were reported at E_{p} = 800 MeV (1987SO1C). See also (1985LE19). An analysis for E_{p} = 201  800 MeV utilizing a semiphenomenological model is discussed in (1993AL05).
Angular distributions of proton groups have been studied for E_{d} = 0.12 to 15 MeV and at 698 MeV: see (1966LA04, 1974AJ01, 1979AJ01, 1984AJ01). J^{π} of ^{7}Li*(0.48) is 1/2^{}. The two higher states have E_{x} = 4630 ± 9 and 7464 ± 10 keV, Γ_{cm} = 93 ± 8 and 91 ± 8 keV. The breakup reactions involve ^{7}Li*(4.63, 7.46) and possibly ^{7}Li*(9.6) [Γ = 0.5 ± 0.1 MeV]: see (1979AJ01). See also ^{8}Be in (1988AJ01) and (1988KO1C). The (d, p)/(d, n) yield ratio for low deuteron energies (E_{d} < 1 MeV) has been studied. Calculations in (1990KO26) concluded that Coulombinduced predissociation of the deuteron should influence the ratio by < 10%. Measurements in (1993CE02) found no evidence of an enhanced ratio for E_{cm} = 20  135 keV. The yield ratio was studied in experiments of (1993CZ01, 1997CZ04). This work explained the chargesymmetry violation in terms of a subthreshold 2^{+} state in ^{8}Be. See also the instrumentationrelated measurements of (1994YE09) and the thicktarget gamma yield measurements of (2000EL08). Calculations involving conservation of channel spin are described in (1996MA36). This reaction was also discussed by (1997NO04) in connection with deduction of the primordial ^{6}Li component. Calculations for energy balance in controlled fusion are described in (2000HA50). See also the compilation of chargedparticleinduced thermonuclear reaction rates in (1999AN35).
The reaction was studied by (1999NA36) for E(^{7}Li) = 65 MeV/A to compare the GamowTeller transition strengths to those deduced from β decay.
The total photoneutron cross section rises sharply from 10 MeV to reach a broad plateau at about 15 mb from 14 to 20 MeV, decreases more slowly to about 0.5 mb at 25 MeV and then decreases further to about 0.3 mb at E_{γ} = 30 MeV (monoenergetic photons): there are indications of weak structure through the entire region: see (1979AJ01), (1988DI02) and (1988AJ01). A study by (1986SI18) reported evidence for the excitation of ^{7}Li*(7.46), as well as of states at E_{x} = 13.75 ± 0.03 and 14.65 ± 0.03 MeV with Γ ≈ 500 and 700 keV [and integrated cross sections of ≈ 0.14 and 0.17 MeV · mb], in addition to a major broad structure at 17 MeV. The integrated cross section to 23 MeV is 39 ± 4 MeV · mb for the n_{0} transition and 17 ± 4 MeV · mb for the n_{1} transition: together these account for 0.4 of the exchange augmented dipole sum of ^{7}Li: see (1979AJ01). The integrated cross section for formation of ^{6}Li*(3.56) is 4 ± 1 MeV · mb to 30 MeV and 11 ± 3 MeV · mb to 55 MeV: see (1984AJ01). The total absorption cross section for ^{nat}Li in the range 10 to 340 MeV shows a broad peak at ≈ 30 MeV (σ_{max} ≈ 3 mb), a minimum centered at ≈ 150 MeV at ≈ 0.3 mb and a fairly smooth increase in cross section to ≈ 3 mb at ≈ 320 MeV: see (1984AJ01). The cross section for the (γ, p) reaction (reaction (c)) shows a maximum at ≈ 15.6 MeV with a width of ≈ 4 MeV. It then decreases fairly smoothly to 27 MeV. The integrated cross section for 11 → 28 MeV is 13.2 ± 2.0 MeV · mb: see (1974AJ01, 1979AJ01, 1984AJ01). Differential cross sections for the (γ, n_{0} + n_{2}) and (γ, p_{0}) processes are reported by (1983SE07, 1985SE17; E_{γ} = 48 to 141 MeV). Photodisintegration cross sections in the giant resonant range were analyzed by (1987VA05). Analyses of photodisintegration data for reactions (a, b, c, d) at E_{γ} < 50 MeV (1990VA16) were used to deduce the role of cluster configuration. Reaction (e) has been studied in the giant resonance region with bremsstrahlung photons, E_{brem} ≤ 30 MeV. Deuteron groups to ^{5}He_{g.s.} and possibly to the first excited state are reported. States of ^{7}Li with E_{x} = 25  30 MeV may be involved when E_{brem} = 37 to 50 MeV is used: see (1979AJ01). At E_{γ} = 0.9 GeV, (1985RE1A) have studied π^{} emission with the population of ^{6}Li*(2.19). The cross section for reaction (f) at 90° displays a broad resonance at E ≈ 7.7 MeV (Γ = 7.2 MeV) with an integrated cross section of 6.2 MeV mb, a plateau for 12 → 22 MeV (at ≈ 0.6 the cross section at 7.7 MeV) and a gradual decrease to 48 MeV. The (γ, t) cross section integrated from threshold to 50 MeV is 8.1 MeV mb: see (1984AJ01), and (1986VO20). More recently, measurements of differential cross sections with linearly polarized photons (E_{γ} < 90 MeV) were reported (1995BU08). Angular distributions at E_{γ} = 6.4, 6.7, 8.5, 9.0 MeV have been measured by (1999LI02). Theoretical studies on this reaction include: a microscopic analysis for E < 70 MeV (1987BU04); an analysis in the giant resonance range (1987VA05); a cluster structure study (E < 50 MeV) (1990ZH19); and a calculation of photodisintegration observables for E < 90 MeV (1998KO17). For earlier work, see references cited in (1988AJ01).
See 7.4 (in PDF or PS) in (1966LA04) [summary of early measurements] for τ_{m} of ^{7}Li*(0.48) = 107 ± 5 fsec. See also (1984AJ01), (1987BE1K) and (1986DU03).
The electric form factor measurements for E_{e} = 100 to 600 MeV are well accounted for by a simple harmonicoscillator shell model with a quadrupole contribution described by an undeformed pshell: r_{r.m.s.} = 2.39 ± 0.03 fm, Q = 42 ± 2.5 mb. From results obtained for E_{e} = 24.14 to 97.19 MeV, r_{r.m.s.} = 2.35 ± 0.10 fm (model independent), 2.29 ± 0.04 fm (shell model). A study of the ratio of the electric charge scattering from ^{6}Li and from ^{7}Li as a function of (momentum transfer)^{2} yields < r^{2} > ^{1/2}_{6}/< r^{2} > ^{1/2}_{7} = 1.001 ± 0.008. The r.m.s. radius of the ground state magnetization density distribution, < r^{2} > ^{1/2}_{M} = 2.98 ± 0.05 fm. See (1979AJ01) for references. More recent theoretical studies include: a study by (1991BE40) which obtained vertex constants from an analysis of form factors; a shellmodel calculation of largebasis space and mesonic effects (1992BO30); a calculation of form factors including meson exchange contributions (1992WA37); and a study of shellmodel structures of low lying states (1997KA24). Inelastic scattering studies show peaks corresponding to ^{7}Li*(0.48, 4.63, 6.68, 7.46): see (1974AJ01) and 7.5 (in PDF or PS). Form factors for ^{7}Li*(0, 0.48) have recently been studied at E_{e} = 80 to 680 MeV (1989LI09, 1990LI21). Theoretical work includes: a calculation by (1989TA31) of cross section and reduced transition matrix elements for oriented nuclei; a calculation for polarized electron and polarized targets (1990LE14); a shell model calculation in a (0 + 2)ℏω space (1990WO10); a study of spin modes (1991AR22); a microscopic cluster calculation (1991UN01); calculation of form factors including meson exchange contribution (1992BO30, 1992WA37); and a shellmodel study of low lying states (1997KA24). For reaction (b) energy and angular distributions were measured at E_{e} = 203 MeV (1999SH25) to study spinisospin flip giant resonances. For reactions (c) and (d) a measurement of the momentum distribution and study of clustering effects was reported in (1989LA22). Calculations discussed in (2000LA17) were used to study correlations in the ^{7}Li groundstate wave function. See also the PWIA calculation for polarized electrons and targets of (1993CA11). See also (1988BO05). For earlier work see the references cited in (1988AJ01).
^{7}Li*(0, 0.48, 4.63, 6.68, 7.46, 9.67) have been populated in this reaction. Angular distributions have been measured at E_{π+} = 49.7 MeV and E_{π±} = 143 and 164.4 MeV: see (1984AJ01). Total and partial cross sections have been obtained for E_{π±} in the range 85 → 315 MeV [see (1984AJ01)] and at E_{π+} = 50 MeV (1983NA18). A measurement of inclusive analyzing power at E_{π} = 134, 164, 194 MeV was reported by (1994ME01). A clustermodel calculation of quadrupole effects is described in (1994NO06). Calculations of pion scattering for E_{π} = 100  240 MeV are described in (2001LE01). Nuclear transition densities predicted by Quantum MonteCarlo calculations were used. The ^{7}Li(π^{}, π^{}p) reaction was studied at 0.7 GeV/c by (2000AB25). For ^{7}Li(π^{+}, π^{}p), see (1998PA31). For the (π^{+}, 2p) reaction see ^{5}He (1986RI01). For studies of (π^{+}, pd) and (π^{±}, pn) see (1986WH01) and (1986YO06), respectively. For π^{+} induced fission of ^{7}Li see (1983BA26). See also references in the General Table for ^{7}Li located on our website at (nucldata.tunl.duke.edu/NuclData/General_Tables/7li.shtml).
Angular distributions have been measured at E_{n} = 0.5  3 MeV (1991AL04), E_{n} = 1.5 to 18 MeV [see (1979AJ01, 1984AJ01)], E_{n} = 5.4, 6.0, 14.2 MeV (1985CH37; n_{0+1}, n_{2}), E_{n} = 6.82  9.80 MeV (1987SC08; n_{0+1}), 7 to 14 MeV (1983DA22; n_{0}), E_{n} = 11, 13 MeV (1988CH09), 8.0 and 24.0 MeV (1988HA25; n_{0} and n_{2} at 24 MeV), E_{n} = 9, 9.5, 10 MeV (1995HU17; n_{1}) and at 14.7 MeV (1984SH01; n_{0+1}). Double differential cross sections were measured at E_{n} = 11.5 and 18.0 MeV (1998IB02). Theoretical work includes: calculations of coherent and incoherent scattering for E_{n} = 0.0728 eV (1987VE02, 1990GO26); DWBA calculations of σ(θ) for inelastic excitation of ^{7}Li*(0, 478 MeV) (1992HU05); multiconfiguration RGM calculations, E_{n} = 9.58  12.2 MeV (1995FU16); and studies of optical model potentials for nuclear data evaluation, E_{n} < 200 MeV (1996CH33). Reaction (b) at E_{n} = 14.4 MeV proceeds primarily via ^{7}Li*(4.63) although some involvement of ^{7}Li*(6.68) may also occur: see (1979AJ01). Cross sections have been measured by activation methods at E_{n} = 14.7 MeV (1987ME18) and 7.9  10.5 MeV (1987QA01). See also the evaluation of tritium production cross section for E < 17 MeV (1990YU02). See also ^{8}Li and references cited in (1988AJ01) and (1985CO18; applications).
Angular distributions of protons have been measured for E_{p} = 1.0 to 185 MeV [see (1974AJ01, 1984AJ01)] and at E_{p} = 1.89 to 2.59 MeV (1986SA1P; p_{0}). Inelastic proton groups have been observed to ^{7}Li*(0.48, 4.63, 6.68, 7.46, 9.6): see (1952AJ38, 1974AJ01). Double differential cross sections for the continuum are reported at E_{p} = 65 MeV and 85 MeV (1987TO06, 1989TO04). Measurements of differential cross sections and analyzing powers for p_{0}, p_{1} and p_{2} for E_{p} = 200 MeV were used to deduce radial transition density differences (1991GL01). Cross sections for inelastic scattering to the ^{7}Li E_{x} = 0.478 MeV level have been measured in applicationrelated experiments for E_{p} = 2.2  3.8 MeV (1988BO37), 3.2  3.6 MeV (1990BO15), 2.5  3.5 MeV (1994MI21), 1.03 MeV (1994WI15), 0.7  3.2 MeV (1995RI14). See also (1999SA16). For reaction (b) see (1984PA1B, 1985PA1B; 50  100 MeV) and (1985BE30, 1985DO16; 1 GeV). See also ^{6}He and (1984AJ01). Cross section measurements at E_{p} = 70 MeV were used to distinguish contributions of 1p and 1s shell nucleons by (1988PA26, 1998SH33). Proton spectra and polarization measurements at E_{p} = 1 GeV are reported by (2000MI17). For reaction (c) see (1986WA11). For reaction (d) see (1985BE30) and ^{6}Li. Reaction (d) has been studied at E_{p} = 200 MeV (1986WA11): the deuteron spectroscopic factor is close to unity and the results indicate that the deuteron cluster momentum distribution is characterized, at small momentum, by a FWHM of 140 MeV/c. For measurements at E_{p} = 70 MeV, see (1998SH33). Cross sections for the (p, pt) reaction (reaction (e)) are very small but are consistent with a spectroscopic factor of unity for t + ^{4}He in ^{7}Li (1986WA11). For reaction (f) recent measurements of cross sections and analyzing powers measured for E_{p} = 296 MeV were used to deduce alpha spectroscopic factor for ^{7}Li (1998YO09). See also (1983GO06, 1985PA1C, 1985PA04). See also ^{5}He and (1984AJ01). See also ^{8}Be in (1988AJ01), and references to earlier work cited in (1988AJ01). For early theoretical work on these reactions see references cited in (1988AJ01). More recent calculations include: threshold effects in elastic scattering for E_{p} = 1.35  3 MeV (1990GU22); differential cross section calculated at high energies with a geometric model (1990HU09); a potential description of ^{7}Li(p, p) with E_{p} < 7 MeV (1992DU07); calculation with a microscopic effective interaction (1993KO44); a folding model description for E_{p} = 25  50 MeV (1993PE13); a microscopic threecluster model calculation for E_{cm} = 0.5  25 MeV, σ(E), S factors (1994DE09); a fully microscopic analysis for E_{p} = 200 MeV (1997DO01); an analysis of E_{p} = 200 MeV data studying shell model structures of low lying ^{7}Li levels (1997KA24); a microscopic analysis of elastic scattering at E_{p} = 25, 30 and 40 MeV (2000DE61), E_{p} = 65 MeV (1998DO16), and at 60  70 MeV (1998FUZP); a resonance opticalmodel calculation for E_{p} = 1  10 MeV (2000LA40); and a GlauberSitenko diffraction theory calculation for E_{p} = 0.16  1.04 GeV (2000ZH50). See also (2000ZH53). Reaction rate uncertainties for reaction (g) were analyzed by (1998FI02).
Angular distributions have been reported for E_{d} = 1.0 to 28 MeV [see (1974AJ01, 1979AJ01)] and at 50 MeV (1988KO1C). See also ^{9}Be in (1988AJ01) and (1987GOZF) for a breakup study.
Angular distributions have been reported at E(^{3}He) = 11 MeV to 44.0 MeV and at E(^{3}He) = 33.3 MeV: see (1974AJ01, 1984AJ01). See also the compilation and analysis of differential cross sections for E(^{3}He) = 24 MeV (1995MI16). The missing mass spectrum in reaction (b) at E(^{3}He) = 120 MeV indicates, in addition to the unresolved group to ^{7}Li*(0, 0.48), a small peak at E_{x} = 17.8 ± 0.5 MeV, possibly some structure between 30 and 40 MeV, a peak at 40.5 ± 0.5 MeV (Γ ≈ 2  3 MeV) and possibly some structure at higher energies (1985FR01). Measurements of cross sections for yields of protons, deuterons, ^{4}He, ^{3}H and ^{3}He from 93 MeV ^{3}He on ^{7}Li are reported by (1994DO32). For pion production see (1984BR22).
Angular distributions (reaction (a)) have been reported for E_{α} = 3.6 to 29.4 MeV [see (1974AJ01, 1984AJ01)] and at E_{α} = 35.3 MeV (1985DI08; α to ^{7}Li*(0, 0.48, 4.63, 6.68, 7.46, 9.67); collective coupled channel analysis). See also (1987BU27). More recently, differential cross sections were measured at E_{α} = 50.5 MeV for inelastic scattering to ^{7}Li*(0, 0.478, 4.63 MeV) by (1996BU06). The α, t cluster spectroscopic factor extracted for the ^{7}Li ground state is S_{α}t = 1.03 ± 0.1. Measurements of target polarization in ^{7}Li(α, α') to E_{x} = 4.63 MeV for E_{α} = 27.2 MeV were reported by (1991KO41). See also coupledchannels calculations for these data (1997DM02). Gamma emission yields for E_{α} = 0.7  3.2 MeV were measured for nuclear microprobe applications by (1995RI14). Reaction (b) has been studied at E_{α} = 18 to 64.3 MeV [see (1974AJ01, 1984AJ01)] and at 27.2 MeV (1985KO29). ^{7}Li*(4.63) is strongly involved in the sequential decay, as are possibly ^{7}Li*(6.68, 7.46). Cross sections measured for E_{α} = 77  119 MeV were used to deduce triton momentum distributions for α + t states in ^{7}Li by (1992WA09). An analysis is reported in (1996JA01). See also references cited in (1988AJ01).
Elastic and inelastic (^{7}Li; E_{x} = 0.476 MeV) differential cross sections for reaction (a) have been reported for E_{α} = 9  40 MeV (1998PO03). See also ^{6}Li. The elastic angular distribution (reaction (b)) has been studied for E(^{7}Li) = 4.0 to 6.5 MeV [see (1974AJ01)] and 2.0 to 5.5 MeV (1983NO08). Elastic and inelastic (^{7}Li; E_{x} = 0.476 MeV) cross sections for E_{α} = 8  17 MeV were measured and analyzed with an optical model (1993BA43, 1997PO03). For reaction (c) cross sections for E(^{11}Li) = 300 MeV were calculated in connection with a study of nuclear matter compressibility (1998GR21).
Elastic angular distributions have been measured at E(^{7}Li) = 34 MeV [see (1979AJ01)] and at 78 MeV (1986GLZV, 1986GLZU; also to ^{7}Li*(4.63)). For the interaction cross section at 790 MeV/A see (1985TA18).
For reaction (a) see ^{10}B in (1988AJ01). Angular distributions have been studied for reaction (b) to ^{7}Li*(0, 0.48) at E(^{7}Li) = 34 MeV (1987CO07, 1987CO02). See also (1987HNZZ).
Angular distributions (reaction (a)) involving ^{7}Li*(0, 0.48) have been studied at E(^{7}Li) = 4.5 to 89 MeV [see (1975AJ02, 1979AJ01, 1984AJ01)] and at E(^{7}Li) = 53.8 MeV and E(^{12}C) = 92.3 MeV (1984VI02, 1986CO02; also to ^{7}Li*(4.63)) and at E(^{7}Li) = 131.8 MeV (1988KA09; ^{7}Li*(0 + 0.48); and various states in ^{12}C) as well as at E(^{7}Li) = 21.1 MeV (1984MO06; elastic). See also (1986GLZU) and ^{12}C in (1985AJ01, 1990AJ01). Breakup studies involving ^{7}Li*(4.63) are reported at E(^{7}Li) = 70 MeV (1986DAZP, 1986YOZU) and 132 MeV (1986SHZP). See also the measurement at E(^{12}C) = 58.4 MeV reported by (1987PA12). The interaction cross section on carbon at 790 MeV/A has been measured by (1985TA18). The elastic scattering in reaction (b) has been studied for E(^{7}Li) = 4.5 to 34 MeV [see ^{13}C in (1986AJ01)] and by (1987CO02, 1987CO16; 34 MeV; also to ^{7}Li*(0.48)). For earlier work, see references cited in (1988AJ01).
Elastic angular distributions (reaction (a)) are reported at E(^{7}Li) = 36 MeV [see (1981AJ01)] and E(^{14}N) = 150 MeV (1986GO1H) while those for reaction (b) have been studied at E(^{7}Li) = 28.8 MeV [see ^{15}N in (1986AJ01)].
The elastic scattering has been studied from E(^{7}Li) = 9.0 to 20 and at 68 MeV [see ^{16}O in (1986AJ04)] as well as at E(^{7}Li) = 50 MeV (1984CO20). For fusion cross sections and breakup studies see (1984MA28, 1986MA19, 1986SC28, 1988MA07). See also (1982GU21, 1988PR02).
Angular distributions have been studied at E(^{7}Li) = 36, 68 and 89 MeV: see ^{20}Ne in (1983AJ01).
The elastic scattering has been studied at E(^{7}Li) = 89 MeV and at 27 MeV (reaction (b)): see (1984AJ01). A study of the breakup on ^{27}Al is reported by (1986NAZV) and the interaction cross section at 790 MeV/A has been measured by (1985TA18). See also (1988OT01, 1988SA10).
Angular distributions involving ^{7}Li*(0, 0.48) and various states of ^{28}Si and ^{40}Ca have been studied at E(^{7}Li) = 45 MeV. The elastic scattering on ^{40}Ca and ^{48}Ca has been studied at E(^{7}Li) = 28, 34 and 89 MeV [the latter also to ^{7}Li*(0.48)]: see (1984AJ01). Angular distributions (reaction (b)) involving ^{7}Li*(0, 0.48) have also been reported at E(^{7}Li) = 34 MeV (1985SA25). See also (1985GO11, 1986SA1D, 1987SA1C).
The decay proceeds to the ground and 0.48 MeV states. The branching ratio to ^{7}Li*(0.48) is 10.44 ± 0.04%, and the adopted halflife is 53.22 ± 0.06 d. Both transitions are superallowed: log ft = 3.32 and 3.55 for the decays to ^{7}Li*(0, 0.48). See also (1979AJ01). The first excited state has E_{x} [from E_{γ}] = 477.612 ± 0.002 keV: see (1984AJ01). A recent investigation of the decay utilized a high efficiency BeO calorimeter developed for use in a ^{7}Li solar neutrino experiment (1998GA08). The decay rate of BeOH_{2} was studied under pressures up to 441 kbar (2000LI21) and showed systematic dependences at the 1% level. A large change in the decay rate for ^{7}Be implanted in Au and Al_{2}O_{3} was observed by (1999RA12) indicating that the chemical environment affects the ^{7}Be lifetime. A further decay study using ^{7}Be in BeO, BeOH_{2} and Be^{2} + (OH_{2})_{4} molecular forms (1999HU20) found considerable variation (≈ 1.5%) in the lifetime. Less significant effects of the chemical environment on the measured halflife have been measured by (1949SE20, 1953KR16, 1956BO36, 1970JO21, 1973HE27). The authors of (2000HU20) deduced a halflife value of 53.42 ± 0.01 d for ^{7}Be in BeOH_{2}. A systematic discussion of ^{7}Be halflives is included in the evaluation of R. Helmer (see 7.6 (in PDF or PS)). Helmer's evaluation produced a generaluse value of the halflife, 53.22 ± 0.06 d, which is intended to be valid for Be and BeO samples and adequate for various chemical forms. In spite of more precise measurements of the ^{7}Be lifetime that show these environmental effects, we presently adopt this value. In related threshold investigations, the polarization of the internal bremsstrahlung has been calculated (1988ME06) as well as the effect of daughter atom ionization (1994RE18) and the fractional electron probablities (1998SC28). For earlier work, see references cited in (1988AJ01).
Total cross sections have been measured at E_{n} = 0.025  13.5 keV (1988KO03). The cross sections obtained for the ^{7}Li ground and first excited states (E_{x} = 0.477 MeV) were 38400 ± 800 b and 420 ± 120 b, respectively. The astrophysical reaction rate N_{A} < σν was calculated. Uncertainties in elemental abundances from primordial nucleosynthesis were deduced in (1998FI02).
Cross sections σ(E) for E_{α} = 2  7 MeV were measured by (1998MIZY). See (1999ZHZN) for a compilation and evaluation of cross section data.
Differential cross sections for E_{α} = 21  39 MeV were measured by (1999SH05). See (1999ZHZN) for a compilation and evaluation of cross section data.
The capture of stopped pions has been studied in a kinematically complete experiment: ^{7}Li*(0, 0.48) are weakly populated. Two large peaks are attributed to the excitation of ^{7}Li*(7.46, 10.25). The recoil momentum distributions corresponding to these peaks are rather similar and both indicate a strong L = 0 component: see (1979AJ01).
An angular distribution is reported at E_{n} = 14.6 MeV (1987ZA01; t_{0+1}). See also (1979AJ01) and ^{10}Be in (1988AJ01). Cross section measurements have also been reported for E_{n} = 12.9  19.6 MeV (1988LI05) and for E_{n} = 16  19.6 MeV with HauserFeshbach calculations (1990WO07).
At E_{p} = 43.7 MeV, angular distributions have been obtained for the ^{3}He particles corresponding to ^{7}Li*(0, 0.48, 4.63, 7.46). The 7.46MeV state is strongly excited while the analog state in ^{7}Be is not appreciably populated in the ^{9}Be(p, t)^{7}Be reaction (see reaction 21 in ^{7}Be). The angular distribution indicates that the transition to ^{7}Li*(7.46) involves both L = 0 and 2, with a somewhat dominant L = 0 character. The J^{π} = 3/2^{}, T = 3/2 state is located at E_{x} = 11.28 ± 0.04 MeV, Γ = 260 ± 50 keV: see (1979AJ01). Reaction (b) at E_{p} = 58 MeV involved ^{7}Li*(0, 0.48, 7.47) (1985DE17). See also (1987KA25).
Angular distributions have been measured for E_{d} = 0.4 to 27.5 MeV [see (1966LA04, 1974AJ01, 1979AJ01)] and at E_{d} = 2.0 to 2.8 MeV (1984AN16; α_{0}, α_{1}). A study at 11 MeV finds Γ_{cm} = 93 ± 25 and 80 ± 20 keV, respectively for ^{7}Li*(4.63, 7.46). No evidence is found for the T = 3/2 state ^{7}Li*(11.25). Differential cross sections measured at E_{d} = 67  75 MeV for excitation of ^{7}Li*(0, 0.48, 4.63, 7.46) were used to deduce spectroscopic amplitudes (1989SZ02). Measurements of vector analyzing powers for ^{7}Li*(0, 0.48) were reported by (1994LY02) for E_{d} = 1.3  3.1 MeV. Measurements at E_{cm} = 57  139 keV (1997YA02) and E_{cm} = 30  130 keV (1997YA08) were used to deduce astrophysical Sfactors. Differential cross sections for E_{d} = 90  290 keV are reported in (2001OCZZ). Astrophysical S factors were deduced. See also (1999OCZZ). The previous review (1988AJ01) notes that in a kinematically complete study of reaction (b) at E_{d} = 26.3 MeV, ^{7}Li*(4.6, 6.5 + 7.5, 9.4) are strongly excited. No sharp αdecaying states of ^{7}Li are observed with 10 < E_{x} < 25 MeV. Parameters for ^{7}Li*(9.7) are E_{x} = 9.36 ± 0.05 MeV, Γ = 0.8 ± 0.2 MeV: see (1979AJ01). [E_{x} = 6.75 ± 0.20 MeV, Γ = 0.87 ± 0.20 MeV (1986PAZN)]. A study of inclusive αspectra at E_{d} = 50 MeV has been reported by (1987KA17) who suggest the involvement of a ^{7}Li state at E_{x} = 18 ± 1 MeV, Γ = 5 ± 1 MeV. For reaction (b) see also (1987VA29). See also ^{11}B in (1990AJ01) and (1988NE1A). In more recent studies of reaction (b), differential cross sections have been measured at E_{d} = 18 MeV (1988GO02, 1988GU20) and E_{d} = 7 MeV (1988SZ02). See also the measurements of σ(E) for E_{d} = 0.9  11.2 MeV (1994AB25), A_{y}(θ) for E_{d} = 1.3  3.1 MeV (1994LY02), σ(θ) at E_{d} = 3  11 MeV (1995AB41) and E_{d} = 8  50 MeV (1995GU22). Astrophysical S factors were determined in measurements at E_{cm} = 57  139 keV (1997YA02, 1997YA08).
Angular distributions involving ^{7}Li*(0, 0.48) have been reported at E(^{6}Li) = 32 MeV (1985CO09) and E(^{9}Be) = 14 MeV (1985JA09). Reaction cross sections have been calculated by (2001BH02) for E(^{6}Li) = 790 MeV/A.
Angular distributions of α_{0}, α_{1} and of α_{2} at the higher energies have been measured from E_{n} = 2 keV to 14.4 MeV: see (1979AJ01, 1984AJ01). τ_{m}(0.48) = 102 ± 5 fsec (1985KO47). More recently measurements of the ground to excitedstate transition ratio σ(n, α_{0})/σ(n, αγ) for E_{n} = 0.2  1.0 MeV were reported by (1991WE11). A relative measurement of the ^{10}B(n, αγ)^{7}Li cross section has been made (1993SC20) for E_{n} = 0.2  4.0 MeV. A study of Podd effects (in the mixing of oppositeparity levels) in this reaction determined forwardbackward asymmetries for the α_{0} and α_{1} groups (3.4 ± 6.7) × 10^{7} and (2.5 ± 1.6) × 10^{7} respectively (1996VE02). Earlier work was reported in (1986ER05, 1994GL07). Measurement and analysis of the Dopplerbroadened gamma line shapes produced in the (n, α, γ) reaction for the purpose of boron concentration determination are described in (1994SA72, 1998MA61). See also (1997SA70). For early polarization studies (involving both n and ^{10}B) see (1986KO19) and ^{11}B in (1990AJ01). See also (1986CO1M; applications). See also the more recent measurements and calculations of (1999VE03) and the measurement at thermal energies of (2000GO03). A calculation of αγ correlation parameters and study of timereversal invariance related features are described in (2000GA43).
See ^{5}Li.
Angular distributions involving ^{7}Li_{g.s.} and ^{7}Be_{g.s.} and ^{7}Li*(0.48) + ^{7}Be*(0.43) have been studied at E_{α} = 91.8 MeV (1985JA12, 1986JA03). See also (1988SH1E; theor.).
Delayed αparticles have been observed in the β^{} decay of ^{11}Be: they are due to the decay of ^{11}B*(9.88) [J^{π} = 3/2^{+}]. This state decays by αemission 87.4 ± 1.2% to the ground state of ^{7}Li and 12.6 ± 1.2% to ^{7}Li*(0.48) (1981AL03). See also ^{11}Be and ^{11}B in (1985AJ01).
Angular distributions involving ^{7}Li_{g.s.} and ^{7}Be_{g.s.} and ^{7}Li*(0.48) + ^{7}Be*(0.43) have been studied at E(^{3}He) = 71.8 MeV (1986JA02, 1986JA03). See also (1987KW01, 1987KW03).
Angular distributions have been measured at E_{α} = 27.2 to 29.0 MeV and at 65 MeV. At E_{α} = 65 and 72.5 MeV, ^{7}Li*(0, 4.63) are very strongly populated while ^{7}Li*(0.48, 6.68, 7.46) are weakly excited: see (1979AJ01, 1984AJ01).
Cross sections were measured at E_{γ} = 27  47 MeV with bremsstrahlung photons by (1998KO77).
Angular distributions involving ^{7}Li_{g.s.} and ^{7}Be_{g.s.} and ^{7}Li*(0.48) + ^{7}Be*(0.43) have been studied at E_{d} = 39.8 MeV [see (1979AJ01)] and at 78.0 MeV (1986JA03, 1986JA15). See also (1984NE1A) and (1987KW01, 1987KW03). More recently differential cross sections at E_{d} = 78 MeV were measured in a study of fivenucleon transfer (1996JA12).
Angular distributions have been studied at E_{t} = 38 MeV to ^{8}Be_{g.s.} and ^{7}Li*(0, 0.48) (1986SIZS).
Angular distributions are reported at E_{α} = 49.0 and 80.1 MeV (1984GO03). See also (1984AJ01). Differential cross sections were measured at E_{α} = 90 MeV by (1991GL03).
Angular distributions have been obtained at E(^{6}Li) = 36 MeV for the transitions to ^{7}Li*(0, 0.48): see (1979AJ01). See also (1986GL1E). More recently differential cross sections and polarization observables were measured at E(^{6}Li) = 50 MeV in a study of mirror states in ^{7}Li, ^{7}Be (1997KE04).
The reaction was studied (1999NA36) at E(^{7}Li) = 65 MeV/A, and GamowTeller transition strengths were compared to those deduced from β decay.
At E_{d} = 14.6 MeV angular distributions are reported for the transitions to ^{7}Li*(0, 0.48) and ^{8}Be_{g.s.}: see (1979AJ01). See also (1984NE1A, 1984SH1D).
At E_{n} = 14.1 MeV, ^{7}Li*(0, 0.48) are approximately equally populated: see (1979AJ01). Differential cross sections have been measured at E_{n} = 14.4 and 18.2 MeV involving ^{8}Be_{g.s.} and ^{7}Li*(0 + 0.48, 4.63) (1986TU02).
Gamma ray intensities and photo production cross sections were measured fo E_{n} = 4  200 MeV by (2001NE09).
At E_{d} = 14.6 to 15.0 MeV, angular distributions have been measured for the transitions to ^{12}C_{g.s.} + ^{7}Li*(0, 0.48) [reaction (a)], ^{13}C_{g.s.}+^{7}Li*(0, 0.48) [reaction (b)] and ^{14}N_{g.s.}+^{7}Li*(0, 0.48) [reaction (c)]: see (1979AJ01). See also (1984AJ01).
A Coulomb breakup experiment reported by (2001TO07) used a 42 MeV ^{7}Li beam incident on target of ^{27}Al, ^{58}Ni, ^{64}Zn, ^{90}Zr, ^{120}Sn, ^{144}Sm, ^{169}Tm, ^{197}Au and ^{208}Pb. The spectra of breakup particles were studied and the astrophysical S factors, S(E) for ^{3}H(α, γ)^{7}Li, were deduced.
Measurements of charged particle multipolarity, angular distributions and rapidity distributions were reported in (2001AB25). ^{7}Li cluster structure was deduced.
Elastic and inelastic cross sections and analyzing powers were measured at E(^{7}Li) = 27 MeV to study the effect of electric dipole polarizability of ^{7}Li (1998MA65).
