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9Li (2004TI06)


(See Energy Level Diagrams for 9Li)

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

See also Table 9.1 preview 9.1 [Table of Energy Levels] (in PDF or PS).

Ground state properties:

μ = 3.4391 ± 0.0006 μN (1983CO11). See also (1987AR22, 2001STZZ);

Q = -27.4 ± 1.0 mb (1992AR07, 2001STZZ).

See also (1988AR17), and see (1992LI24, 1993NE08).

The isospin quartets which contain the ground and first-excited states of 9Li are well established (1974BE66, 1974KA15). The energies, widths, and relative cross sections in the 7Li(t, p)9Li reaction for the states listed in Table 9.1 preview 9.1 (in PDF or PS) are consistent with the expected properties of the first five p-shell states (see the discussion of reaction 4). The lowest positive-parity states are expected between 4 and 5 MeV in excitation energy but could be very broad on account of s-wave parentage to 8Li. The lowest 2ℏω state is predicted just above 5 MeV [B.A. Brown, private communication].

1. 9Li(β-)9Be Qm = 13.6067

The half-life of 9Li is 178.3 ± 0.4 msec: see (1979AJ01). See also (1986CU01, 1988SA04, 1991RE02). 9Li decays to a number of states in 9Be: see reaction 12 in 9Be and Table 9.8 preview 9.8 (in PDF or PS). The nature of the decay to 9Be*(0, 2.43) with Jπ = 3/2-, 5/2- is evidence for Jπ = 3/2- for 9Lig.s.. The probability for delayed neutron decay, Pn, 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 9Be (2003PR11). See also (1990NY01, 1993CH06) and references cited in (1984AJ01, 1988AJ01).

2. 1H(8He, 8He)1H Eb = 13.933

From an analysis of the excitation function for 8He + p elastic scattering obtained by the thick target inverse kinematics method, three T = 5/2 states of 9Li were identified at Ex = 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 9He (2003RO07).

3. 1H(9Li, 9Li)1H

The elastic scattering angular distribution was measured at E(9Li) = 703 MeV/A and analyzed using Glauber multiple-scattering theory to obtain an r.m.s. matter radius for 9Li of 2.43 ± 0.07 fm (2002EG02).

4. 7Li(t, p)9Li Qm = -2.3857

Protons are observed to excited states at Ex = 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 Et = 11.3 (1964MI04; p0), 15 (1971YO04; p0, p2, p4) and 23 MeV (1978AJ02; p0, p1, p2, p4). It is plausible that the observed levels can be identified with the first five predicted p-shell levels with Jπ = 3/2-, 1/2-, 5/2-, and 7/2- (1971YO04). The largest two-neutron 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 n0, n1 and the 7/2- state mainly via n2. See also 10Be (1987AB15, 1990GU36).

5. 9Be(γ, π+)9Li Qm = -153.1769

The angular distribution of the π+ to 9Lig.s. has been measured at Ee = 200 MeV (1983SH19). For the earlier work see (1984AJ01).

6. 9Be(π-, γ)9Li Qm = 125.9635

Capture branching ratios to 9Li*(0, 2.69) are reported by (1986PE05).

7. 9Be(n, p)9Li Qm = -12.8244

Double differential cross sections were measured at En = 96 MeV (2000DA22). Cross sections for reactions to the 9Li ground state and to the first excited state (Ex = 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 En = 198 MeV, the ground and first excited states are clearly seen, as is a strong spin-dipole peak centered near an excitation energy of 7 MeV (1988JA1K).

8. 9Be(t, 3He)9Li Qm = -13.5881

The 0° cross section for Et = 381 MeV shows a weak ground-state transition and a strong spin-dipole peak at Ex ≈ 6.5 MeV (1998DA05).

9. 9Be(7Li, 7Be)9Li Qm = -14.4689

See (1984GL06: E(7Li) = 78 MeV).

10. 11B(6Li, 8B)9Li Qm = -25.121

At E(6Li) = 80 MeV the angular distribution to 9Lig.s. has been measured. States at Ex = 2.59 ± 0.10, 4.36 ± 0.10 and 6.38 ± 0.12 MeV are also populated: see (1977WE03).

11. natAg(14N, 8Li + n)X

Neutron unbound states in light fragments from 14N - Ag reactions at 35 MeV/A were studied by (1989HE24). They report a measurement of a 9Li level at Ex = 4.296 ± 0.015 MeV, Γ = 60 ± 45 keV.

12. natPb(9Li, 8Li + n)X

Coulomb dissociation of 28.53 MeV/A 9Li on targets of Pb and U was studied by (1998ZE01) to determine an upper limit for the 8Li(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 8Li(n, γ) in (1991MA04).

13. natU(9Li, 8Li + n)X

See reaction 12.