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USNDP

19Ne (95TI07)


(See Energy Level Diagrams for 19Ne)

GENERAL: See Tables 19.26 [General Table] (in PDF or PS) and 19.27 [Table of Energy Levels] (in PDF or PS) here.

μg.s. = -1.88542 (8) nm (82MA39)
μ0.239 = -0.740 (8) nm (78LEZA)

1. 19Ne(β+)19F Qm = 3.238

We adopt the half-life of 19Ne suggested by (83AD03): 17.34 ± 0.09 s. See also (78AJ03). The decay is principally to 19Fg.s.: see Table 19.29 (in PDF or PS). The 19Ne decay to 19F*(0.11) [Jπ = 1/2+ --> 1/2-] proceeds by vector and axial vector weak currents, with the former making a negligible contribution. The measured decay rates are roughly an order of magnitude smaller than predicted using the 0 h-barω + 1 h-barω shell model (81AD05, 83AD03). Decay of polarized 19Ne is consistent with time-reversal invariance: see (87AJ02, 88SE11, 93CA1K). See also (88BR1D, 88SA12, 89SA55, 91NA05, 91SAZX, 92HE12, 92SE08, 93SE1B).

2. 15O(α, γ)19Ne Qm = 3.529

(86LA07) have recalculated the 15O(α, γ) direct capture rate at stellar energies. (90MA05) have measured the branching ratios Γαtotal for Ecm = 850, 1020, 1071, 1183 and 1563 keV resonances in 15O + α. The strengths of these resonances were determined (see Table 19.30 (in PDF or PS)) and the reaction rate for temperatures between 7 x 108 and 3 x 109 K was determined to differ from theoretical calculations (86LA07, 88CA1N) by no more than 20%. See also (88BU01, 88TR1C). A recent measurement by (95MA1A) determined Γα for Ex = 4.033 keV and hence the resonant rate for 15O(α, γ) at astrophysical energies.

3. (a) 16O(3He, γ)19Ne Qm = -3.196 Eb = 8.443
(b) 16O(3He, n)18Ne Qm = -11.420
(c) 16O(3He, p)18F Qm = 2.032
(d) 16O(3He, d)17F Qm = -4.894
(e) 16O(3He, 3He')16O
(f) 16O(3He, α)15O Qm = 4.914
(g) 16O(3He, 7Be)12C Qm = -5.576

Excitation functions at 90° for γ0-2, γ3-5 and γ6 [reaction (a)] have been measured for E(3He) = 3 to 19 MeV (83WA05): see Table 19.31 (in PDF or PS) for a listing of the resonances reported in this and in the other channels. See also (83AJ01, 87AJ02) and (90AB1G, 91SU17, 92CO08).

4. 16O(α, n)19Ne Qm = -12.134

Gamma transitions have been observed from the first six excited states of 19Ne: see Table 19.25 (in PDF or PS) in (78AJ03) and Table 19.28 (in PDF or PS) here. Angular distributions of many neutron groups have been studied at Eα = 41 MeV: see (83AJ01).

5. 16O(6Li, t)19Ne Qm = -7.352

This reaction and the mirror reaction 16O(6Li, 3He)19Fhave been studied at E(6Li) = 24, 35, 36, and 46 MeV: see (78AJ03, 83AJ01). Table 19.16 (in PDF or PS) displays the analog states observed in the two reactions. In addition triton groups are reported to states with Ex = 6.08, 6.28, 6.85, 7.21, 8.08, 8.45, 8.94, 9.81, 10.01, 11.08, 11.24, 11.40, 12.56 [all ± 0.02], 13.1, 13.22, 14.18, 14.44, 14.78 [remaining, ± 0.3] MeV. See also (83CU02) and the preliminary report in (92ROZZ).

6. 16O(10B, 7Li)19Ne Qm = -9.345

This as well as the analog reaction [16O(10B, 7Be)19F] have been studied at E(10B) = 100 MeV. On the basis of similar yields and Ex, and in addition to the low-lying analogs, it is suggested that the following pairs of states are analogs in 19F - (19Ne): 8.98 (8.94), 11.33 (11.09), 12.79 (12.48), 14.15 (14.17), 14.99 (14.61) and 15.54 (15.40) [ ± 100 keV]; however, problems of energy resolution are evident. See (83AJ01) for references on this and on other heavy-ion induced reactions.

7. 16O(12C, 9Be)19Ne Qm = -17.836

This 3He stripping reaction was studied at E(12C) = 480 MeV (88KR11). The ground state, 0.2 MeV doublet and 1.5 MeV multiplet were weakly populated. High spin states at 2.8 MeV (9/2+) and 4.64 MeV (13/2+) were strongly populated and were inferred to belong to the (sd)3, 2N + L, g.s. band with ((1d5/2)22s1/2)9/2+ and (1d5/2)313/2+ configurations. Levels at 8.9, 9.88 and 10.41 MeV were inferred to have spin parities of 11/2-, 11/2+, and 13/2+. A 17/2- spin parity was proposed for the strongly populated 12.3 MeV level.

8. 17O(3He, n)19Ne Qm = 4.300

Neutron-γ coincidence measurements lead to the determination of excitation energies [Ex = 4032.9 ± 2.4, 4140 ± 4, 4197.1 ± 2.4, 4379.1 ± 2.2, 4549 ± 4, 4605 ± 5, 4635 ± 4 and (5097 ± 10) keV], τm and branching ratios (see Table 19.28 (in PDF or PS)). On the basis of these it is suggested that 19Ne*(4.14, 4.20) are the analogs of 19F*(4.03, 4.00) [Jπ = 9/2-, 7/2-] and that 19Ne*(4.55, 4.60) are the analogs of 19F*(4.556, 4.550) Jπ = 5/2+, 3/2-]. There is no evidence for a reported state at Ex = 4.78 MeV: see (78AJ03).

9. 18O(p, π-)19Ne Qm = -134.812

This reaction (at Ep = 201 MeV) selectively populates stretched 2p-1h states, in particular 19Ne*(4.64) [Jπ = 13/2+] and a structure near 10 MeV. Angular distributions and Ay are reported for 19Ne*(0, 2.80, 4.6) (86KE04). See also (87AJ02) and (90KU1H).

10. 19F(p, n)19Ne Qm = -4.020

For a review of threshold measurements see (72AJ02, 76FR13). Measurements of the total cross section from threshold (Ep = 4.24 MeV) to Ep = 28 MeV are reported by (90WA10). Excited states of 19Ne determined from γ-spectra are displayed in Table 19.25 (in PDF or PS) of (78AJ03). Branching ratio and τm measurements are summarized in Table 19.28 (in PDF or PS) here. For the g-factor of 19Ne*(0.24) see Table 19.27 (in PDF or PS). Angular distributions have been measured at Ep = 160 MeV to 19Ne*(0[0], 1.54[(0 + 2)], 5.4[0], 6.2[(0 + 1)], 7.1[(0 + 1)], 7.7[(0 + 1)], 8.60[(0)], 10.2[(1)], 11.0 [0], 12.1) (84RA22; [transferred angular momentum in brackets] also forward-angle σ(θ) at Ep = 120 MeV). Spin-transfer coefficients were measured at Ep = 120, 160 MeV by (90HUZY). See also 20Ne in (87AJ02) and (87TA13, 89RA1G).

11. 19F(3He, t)19Ne Qm = -3.257

Angular distributions have been obtained for the triton groups to 19Ne*(0.24, 1.54, 2.79) at E(3He) = 26 MeV: see (78AJ03). 19Ne levels at Ex = 7.060/7.088, 7.500, 7.531 and 7.620 MeV were measured to obtain Γpα branching ratios (0.58 ± 0.08, 2.7 ± 0.9, 0.29 ± 0.09, and 0.34 ± 0.05, respectively) for determination of possible HCNO breakout reactions 18F(p, γ)19Ne and 18F(p, α)15O(α, γ)19Ne (93UTZZ).

12. (a) 20Ne(n, 2n)19Ne Qm = -16.864
(b) 20Ne --> 19Ne + n

Theoretical calculations of neutron-induced reaction cross sections on 20Ne in the energy range 1 - 30 MeV were performed (91RE10). The shape and magnitude of the neutron yield from the breakup of 20Ne [reaction (b)] was calculated in the high-energy region using diffraction theory of processes of fragmentation of complex nuclei.

13. 20Ne(3He, α)19Ne Qm = 3.713

Alpha groups have been observed to 19Ne states with Ex < 10.6 MeV: see Tables 19.27 (in PDF or PS) and 19.32 (in PDF or PS). Angular distributions have been measured for E(3He) = 10 to 35 MeV: see (72AJ02). DWBA analysis of the strongest transitions leads to the l and Jπ values shown in Table 19.32 (in PDF or PS). 19Ne*(0, 0.24, 1.54, 2.79) are identified as members of the Kπ = 1/2+ rotational band [with 19Ne*(4.38) as the 7/2+ member] and 19Ne*(0.28, 1.51, 1.62) with the Kπ = 1/2- band. Candidates for the 7/2- and 9/2- members of the Kπ = 1/2- band are thought to be 19Ne*(4.15, 4.20). Possible matching of other 19Ne states with those in 19F is also discussed: see (72AJ02). For lifetime and radiative decay measurements see Table 19.28 (in PDF or PS). See also (87AJ02) and see (89MC1C) for use of this reaction for observing parity-violating effects.

14. 21Ne(p, t)19Ne Qm = 15.144

At Ep = 40 MeV the angular distributions to 19Ne*(0.24, 4.03, 5.09) are well described by L = 2, 0 and 4, respectively. 19Ne*(4.03), Jπ = 3/2+, has a dominant 5p-2h configuration. 19Ne*(5.09) has positive parity and the data are consistent with J = 5/2. At Ep = 45 MeV the triton group to a state with Ex = 7.620 ± 0.025 MeV has an angular distribution [L = 0] which is similar to that for 19F*(7.66); both are thought to be the analogs of the (Jπ; T) = (3/2+; 3/2) 0.096 MeV first excited state of 19O. The ground state of 19O has Jπ = 5/2+; L for the analog state should be 2. 19Ne*(0, 2.79) are also populated: see (78AJ03, 83AJ01).