
^{9}Li (2004TI06)(See Energy Level Diagrams for ^{9}Li) GENERAL: References to articles on general properties of ^{9}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 ^{9}Li located on our website at (www.tunl.duke.edu/nucldata/General_Tables/9li.shtml). See also 9.1 [Table of Energy Levels] (in PDF or PS). Ground state properties:
The isospin quartets which contain the ground and firstexcited states of ^{9}Li are well established (1974BE66, 1974KA15). The energies, widths, and relative cross sections in the ^{7}Li(t, p)^{9}Li reaction for the states listed in 9.1 (in PDF or PS) are consistent with the expected properties of the first five pshell states (see the discussion of reaction 4). The lowest positiveparity states are expected between 4 and 5 MeV in excitation energy but could be very broad on account of swave parentage to ^{8}Li. The lowest 2ℏω state is predicted just above 5 MeV [B.A. Brown, private communication].
The halflife of ^{9}Li is 178.3 ± 0.4 msec: see (1979AJ01). See also (1986CU01, 1988SA04, 1991RE02). ^{9}Li decays to a number of states in ^{9}Be: see reaction 12 in ^{9}Be and 9.8 (in PDF or PS). The nature of the decay to ^{9}Be*(0, 2.43) with J^{π} = 3/2^{}, 5/2^{} is evidence for J^{π} = 3/2^{} for ^{9}Li_{g.s.}. The probability for delayed neutron decay, P_{n}, is (50.8 ± 0.9)%, obtained by averaging (50.0 ± 1.8)% from (1991RE02) and (51.0 ± 1.0)% from (1992TE03). A recent study has concentrated on the decays to the highest accessible states in ^{9}Be (2003PR11). See also (1990NY01, 1993CH06) and references cited in (1984AJ01, 1988AJ01).
From an analysis of the excitation function for ^{8}He + p elastic scattering obtained by the thick target inverse kinematics method, three T = 5/2 states of ^{9}Li were identified at E_{x} = 16.0 ± 0.1, 17.1 ± 0.2, and 18.9 ± 0.1 MeV. The corresponding widths are < 100, 800 ± 300, and 240 ± 100 keV, respectively. The properties of the three levels are compared with the apparent analog states in ^{9}He (2003RO07).
The elastic scattering angular distribution was measured at E(^{9}Li) = 703 MeV/A and analyzed using Glauber multiplescattering theory to obtain an r.m.s. matter radius for ^{9}Li of 2.43 ± 0.07 fm (2002EG02).
Protons are observed to excited states at E_{x} = 2.691 ± 0.005, 4.31 ± 0.02, 5.38 ± 0.06 and 6.430 ± 0.015 MeV. The widths of the three states above the neutron threshold are 100 ± 30, 600 ± 100 and 40 ± 20 keV, respectively. Angular distributions have been studied at E_{t} = 11.3 (1964MI04; p_{0}), 15 (1971YO04; p_{0}, p_{2}, p_{4}) and 23 MeV (1978AJ02; p_{0}, p_{1}, p_{2}, p_{4}). It is plausible that the observed levels can be identified with the first five predicted pshell levels with J^{π} = 3/2^{}, 1/2^{}, 5/2^{}, and 7/2^{} (1971YO04). The largest twoneutron spectroscopic factors are for the ground state (L = 0) and the 5/2^{} state (L = 2), consistent with the observed angular distributions and the fact that the 4.3 MeV level has the largest cross section. The excited 3/2^{} state is predicted to decay via n_{0}, n_{1} and the 7/2^{} state mainly via n_{2}. See also ^{10}Be (1987AB15, 1990GU36).
The angular distribution of the π^{+} to ^{9}Li_{g.s.} has been measured at E_{e} = 200 MeV (1983SH19). For the earlier work see (1984AJ01).
Capture branching ratios to ^{9}Li*(0, 2.69) are reported by (1986PE05).
Double differential cross sections were measured at E_{n} = 96 MeV (2000DA22). Cross sections for reactions to the ^{9}Li ground state and to the first excited state (E_{x} = 2.69 MeV) were analyzed and compared with DWBA calculations. A Gamow Teller unit cross section was determined for the (weak) ground state transition. At E_{n} = 198 MeV, the ground and first excited states are clearly seen, as is a strong spindipole peak centered near an excitation energy of 7 MeV (1988JA1K).
The 0° cross section for E_{t} = 381 MeV shows a weak groundstate transition and a strong spindipole peak at E_{x} ≈ 6.5 MeV (1998DA05).
See (1984GL06: E(^{7}Li) = 78 MeV).
At E(^{6}Li) = 80 MeV the angular distribution to ^{9}Li_{g.s.} has been measured. States at E_{x} = 2.59 ± 0.10, 4.36 ± 0.10 and 6.38 ± 0.12 MeV are also populated: see (1977WE03).
Neutron unbound states in light fragments from ^{14}N  Ag reactions at 35 MeV/A were studied by (1989HE24). They report a measurement of a ^{9}Li level at E_{x} = 4.296 ± 0.015 MeV, Γ = 60 ± 45 keV.
Coulomb dissociation of 28.53 MeV/A ^{9}Li on targets of Pb and U was studied by (1998ZE01) to determine an upper limit for the ^{8}Li(n, γ) reaction at astrophysical energies. Cross sections calculated in a potential model by (1999BE46) were compared with the data of (1998ZE01). See also the reaction cross section measurements at 80 MeV/A discussed in (1991BL10, 1992BL10), and see the shell model calculation for ^{8}Li(n, γ) in (1991MA04).
See reaction 12.
