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10Li (2004TI06)

(See Energy Level Diagrams for 10Li)

GENERAL: References to articles on general properties of 10Li published since the previous review (1988AJ01) are grouped into categories and listed, along with brief descriptions of each item, in the General Tables for 10Li located on our website at: (www.tunl.duke.edu/nucldata/General_Tables/10li.shtml).

10Li Ground-State Mass: The mass excess of 10Li adopted by (2003AU03) is 33051 ± 15 keV. This indicates that this nucleus is neutron unbound by 25 ± 15 keV. The width of this state is 230 ± 60 keV (2003AU03). The general consensus for the 10Li ground state configuration is that a broad s-wave neutron resonance couples with the 3/2- 9Li ground state to give either 1- or 2- resonance; see reaction 7. This state has been referred to as a virtual resonance in the n + 9Li system with an energy < 50 keV, based on scattering length considerations (2002GA12).

Although most experimental effort has focused on resonances near the threshold energy, the situation at higher excitation energies is better understood. Two resonances near Eres = 250 keV and 500 keV (above the 9Li + n threshold) have been observed under various experimental conditions. In addition, the work of Bohlen et al. (e.g. (1999BO26)) has resulted in the observation of several higher-lying 10Li resonances. Table 10.3 preview 10.3 (in PDF or PS) shows a summary of observed resonances reported for 10Li. Energies in Table 10.3 preview 10.3 (in PDF or PS) are given relative to the 9Li + n threshold energy.

1. (a) 1H(11Li, p + n)8LiX
(b) 1H(11Li, p + n)9LiX

The separation-energy distribution for 83 MeV/A 11Li incident on a CH2 target was measured by (1997KO07). Two states in 10Li at Eres = 5.2 MeV and 0.4 MeV were observed in reactions (a) and (b), respectively. (Eres is the resonance energy relative to the 9Li + n threshold). s-wave properties of the 9Li + n potential were studied (2002MA77) by calculation of the break-up reactions of a 11Li beam.

2. 2H(9Li, p)10Li Qm = -2.250

The structure of 10Li was investigated in a kinematically complete experiment using the 9Li(d, p)10Li reaction in inverse kinematics at E(9Li) = 20 MeV/A (2003SA07). The resulting Q-value spectrum was best fit with a single resonance at Eres = 0.35 ± 0.11 MeV or two resonances located at Eres = 0.77 ± 0.24 MeV and Eres ≥ 0.2 MeV.

3. 9Be(9Be, 8B)10Li Qm = -33.277

In an experiment at E(9Be) = 40.1 ± 0.1 MeV/A the measured energy spectrum of 8B particles was best fit with a single p-wave resonance at Eres = 0.50 ± 0.06 MeV, Γ = 400 ± 60 keV (1999CA48) . An excess strength at threshold was observed but that strength could not be definitely attributed to a 10Li level. No higher states were observed. This work reported in (1999CA48) also included a review of previous measurements of 10Li.

In early work (1975WI26) cited in (1988AJ01) 10Li was observed for E(9Be) = 121 MeV with a differential cross section (cm) ≈ 30 mb/sr at θ = 14° (lab). The observed group corresponds to Eres = 0.80 ± 0.25 MeV, Γ = 1.2 ± 0.3 MeV. However, these levels were not observed in (1999CA48).

4. 9Be(11Be, X)10Li

An experimental study (2001CH46) of the reaction products of 46 MeV/A 11Be on 9Be found that only 7 ± 3% of the 9Li residues are in coincidence with the 2.7 MeV γ rays corresponding to the 9Li first excited state. This implies that the low-energy neutrons from the decay of 10Li represent a direct l = 0 transition to the 9Li ground state. The authors of (2001CH46) present arguments that this result indicates that the valence neutron corresponding to 10Lig.s. is in a 1/2+ intruder state from the sd shell rather than the 1/2- state that might be expected to correspond to a single neutron hole in the p-shell. See also (2001CH31).

5. 9Be(13C, 12N)10Li Qm = -35.916

This reaction at Elab = 336 MeV was used in a study of 10Li (1993BO03) in which levels at Eres = 0.4, 0.8, and 4.5 MeV were reported. Later work by (1998BO38, 1999BO26) did not report these levels. This reaction was also used at Elab = 336.4 MeV along with 10Be(12C, 12N)10Li (reaction 8: Elab = 357.0 MeV) and 9Be(15N, 14O)10Li (reaction 6: Elab = 240 MeV) to study 10Li (1998BO38, 1999BO26). The (12C, 12N) reaction shows a distinct selectivity for unnatural parity states, whereas natural parity states in 10Li are more strongly populated by 9Be(13C, 12N)10Li. A summary discussion and analysis of the results of these experiments is given in (1999BO26), and the parameters for eight levels are presented. See Table 10.4 preview 10.4 (in PDF or PS) here. See also (1997BO10).

6. 9Be(15N, 14O)10Li Qm = -29.609

This reaction was used (1998BO38) at Elab = 240 MeV along with 9Be(13C, 12N)10Li (reaction 5: Elab = 336.4 MeV) and 10Be(12C, 12N)10Li (reaction 8: Elab = 357 MeV) in a study of 10Li. See also (1999BO26) and Table 10.4 preview 10.4 (in PDF or PS) here.

7. 9Be(18O, 9Li + n)X

In an experiment performed with 80 MeV/A 18O on 9Be (1999TH01), the decay structure of 10Li was studied using the method of sequential neutron decay spectroscopy (SNDS). Evidence for low-lying s-wave strength was observed which supports arguments that 10Li should have a ground state in which the p3/2 proton is coupled to the s1/2 neutron to form a 1- or 2- state.

8. 10Be(12C, 12N)10Li Qm = -37.782

This reaction was studied at Elab = 357 MeV along with 9Be(13C, 12N)10Li (reaction 5: Elab = 336.4 MeV) to determine the structure of 10Li (1997BO10, 1998BO38, 1999BO26). See also reaction 6. The 10Be(12C, 12N)10Li reaction shows a distinct selectivity for unnatural-parity states. 10Li states at Eres = 0.24, 1.40, 4.19, and 4.64 MeV are identified in reaction 8. Parameters for these states and four others are presented in a summary table in (1999BO26) and in Table 10.4 preview 10.4 (in PDF or PS) here.

9. 11Be(d, 3He)10Li Qm = -14.672

This reaction was studied in inverse kinematics with 11Be at 35 MeV/A incident on a deuterium target (2000FO17).

10. 11B(π-, p)10Li Qm = 107.898

Inclusive spectra of protons, deuterons and tritons from the absorption of stopped pions in 11B were measured by (1990AM05). They reported observation of the 10Li ground state at a 9Li + n resonance energy, Eres = 0.15 ± 0.15 MeV with a width Γres < 0.4 MeV.

In more recent work (1998GO30), stopped pions were used for 11B(π-, p)10Li along with 14C(π-, dd) (reaction 15). Missing-mass spectra were measured. An analysis of 11B(π-, p) in terms of a one-peak description gave a resonance energy and width Eres = 0.48 ± 0.10 MeV, Γres = 0.50 ± 0.10 MeV. An appreciably better description in terms of two peaks gave Eres = 0.1 ± 0.1 MeV, Γres = 0.4 ± 0.1 MeV and Eres = 0.7 ± 0.2 MeV, Γres = 0.1 ± 0.1 MeV. It is suggested that the lower of these two states is the 10Lig.s. with unnatural parity. These results are compared with other available data in 10Li. For results of their analysis of 14C(π-, dd) see reaction 15.

11. 11B(7Li, 8B)10Li Qm = -32.397

An experiment at E(7Li) = 18.8 MeV/A was reported by (1994YO01). A broad state in the 5° reaction products was best fit by a single p1/2 resonance at Eres = 538 ± 62 keV with a width Γlab = 358 ± 23 keV. However, two p-wave states separated by no more than 160 keV could not be ruled out as the components of the dominant peak in the spectrum. In addition the data show weak evidence for a narrow s- or p-wave resonance that is unbound to neutron decay by less than 100 keV (Γ ≈ 230 keV).

12. (a) natC(11Li, 9Li + n)X
(b) natC(11Be, 9Li + n)X

Reaction (a) and (b) were studied at 280 and 460 MeV/A, respectively, by (1995ZI03). Analysis of the momentum distributions led to the conclusion that 10Lig.s. is a virtual state in n + 9Li with a scattering length as < -20 fm and excitation energy ≤ 50 keV. A study (1997ZI1F, 1997ZI04) of 11Li on carbon (reaction (a)) and Pb (reaction 16) utilized invariant-mass spectroscopy. Resonance-like structures were observed with Eres = 0.21 ± 0.05 MeV, Γres = 0.12+0.10-0.05 MeV; Eres = 0.62 ± 0.10 MeV, Γres = 0.6 ± 0.1 MeV; Eres ≈ 1.6 MeV. The relative intensities of the first two structures are 0.26 ± 0.10 and 0.74 ± 0.10, respectively. The low-energy behavior of the lowest resonance is only reproduced for l = 0, indicating a low-lying s-wave scattering state, but the authors caution that the parameterization of the apparent peak that leads to Eres = 0.21 MeV is not ideal for fitting a low-lying s-wave scattering state.

13. natC(18O, 9Li + n)X

A study of the neutron decay of 10Li produced by 80 MeV/A 18O incident on a carbon target was reported by (1993KR09). Neutrons and 9Li nuclei were detected in coincidence in a collinear geometry. Analysis of the relative velocity spectrum indicated a 10Li state which the authors conclude is consistent with the 10Li ground state at Eres = 0.15 ± 0.15 MeV above the 9Li + n threshold reported by (1990AM05). The authors explored the possibility that if 9Li*(2.7) plays a role in the breakup, then their observation would be consistent with a 10Li state at Ex = 2.5 MeV. However the work of (2001CH46) indicates that 9Li*(2.7) plays a minor role in the reaction (see reaction 4).

14. 13C(14C, 17F)10Li Qm = -28.858

This reaction was studied at Elab = 337 MeV along with 9Be(13C, 12N)10Li (reaction 5: Elab = 336 MeV) by (1993BO03). Only one broad peak was observed in the (14C, 17F) spectrum at 3.8° - 7.0°. Analysis of the peak failed to give a unique solution, but it supported the identification of levels reported in the (13C, 12N) spectrum in (1993BO03). See, however, the later work reported by the same authors (discussed under reaction 5) which did not confirm these levels.

15. 14C(π-, d + d)10Li Qm = 83.268

The reaction, along with 11B(π-, p) (reaction 10), was studied with stopped pions (1998GO30). The (π-, d + d) reaction indicated a 10Li state with Eres = 0.40 ± 0.10 MeV, Γres = 0.30 ± 0.07 MeV and conformed with the results of 11B(π-, p) (see reaction 10) and the results of (1993BO03) and (1994YO01). The (π-, d + d) reaction also indicates a state with Eres = 5.2 ± 0.2 MeV, Γres ≈ 0.4 MeV (1998GO30).

16. natPb(11Li, 9Li + n)X

See reaction 12 and (1997ZI1F, 1997ZI04).