(See Energy Level Diagrams for 19Ne)
Pion capture and reactions1:(EC72).
1 A γ-ray with Eγ = 275.34 ± 0.50 keV is reported by Backenstoss et al. [quoted in (EC72).]. The identification of the γ-ray is not certain (EC72).
μ0.239 = -0.74 nm (FU76H).
The half-life of 19Ne is 17.43 ± 0.06 sec (EA62A), 17.36 ± 0.06 sec (GO68L, WI74M), 17.219 ± 0.017 sec (AZ75A). See Table 19.22 (in PDF or PS) in (72AJ02) for earlier measurements. We adopt τ1/2 = 17.22 ± 0.02 sec. See also (VI77). The decay is principally to 19Fg.s. [log ft = 3.237 ± 0.001 (AL76B)]. The allowed nature of the decay to the ground state of 19F sets Jπ = 1/2+ for 19Neg.s.. A very weak branch is also observed to 19F*(1.55): the branching ratio is (2.1 ± 0.3) x 10-3 % [log ft = 5.72 ± 0.06]; Eγ = 1356.92 ± 0.15 keV for the transition 19F*(1.55 --> 0.20) (AL76B). Other values for this branching ratio are (8.2 ± 2.0) x 10-4% (FR75), < 3 x 10-3% (MA74L, MA75CC). The ratio of εK/β+ is (9.6 ± 0.3) x 10-4 (LE72O).
(BA77E) have studied the triple angular correlation 19F + ν, and find a preliminary result of D = (-0.62 ± 0.88) x 10-3, which is consistent with T-invariance and which corresponds to a phase difference between the axial-vector and vector weak coupling constants of φ = 180.07 ± 0.10°. For an earlier experiment on the existence of second class currents see (CA75L, VA74O). See also (72AJ02, CA75S, CA76A, SI76B, BA77C) and (HO72H, LA73, MU73L, WI73B, WI73D, LE74F, WI74F, CA75M, AZ77A, HO77E, KL77, KU77, LE77H; theor.).
The capture cross section at the 2.40 MeV resonance (reaction (a)) is < 0.8 μb (BR59D). Studies of the excitation functions for reactions (c) and (e) [α0, p1+2+3+4, p5, p6, p7] for E(3He) = 2.0 to 3.0 MeV are interpreted in terms of two resonances at E(3He) = 2.400 and 2.425 MeV (19Ne*(10.46, 10.48)) with Γ = 355 and 45 keV, Jπ = 1/2+ and 3/2+, respectively (BR59D, SI61B). Studies of the (p0, p1, p5) yields, of the elastic yield (reaction (d)), and the analysis of angular distributions in the range E(3He) = 4.3 to 5.6 MeV show the presence of a single resonance at E(3He) = 5.05 ± 0.05 MeV [19Ne*(12.69)], Γ = 180 ± 40 keV, Jπ = 1/2+ (RO67F). A resonance-like structure is also reported at E(3He) ~ 9.5 MeV in the yields of neutron groups (reaction (b)) (AD70). See also (GA76J).
The elastic scattering (reaction (d)) and the α0 yield (reaction (e)) have been studied for E(3He) = 3.2 to 7.0 MeV by (OT72). They report a state at Ex = 11.51 ± 0.05 MeV [E(3He) = 3.65 MeV] with Jπ = 3/2- or (1/2-), Γcm = 25 keV. In addition, two states at Ex = 12.23 and 12.40 MeV (± 0.05 MeV) [E(3He) = 4.50 and 4.70 MeV], Jπ = 5/2+ and 7/2+, Γcm = 200 and 180 keV (± 25 keV) respectively, are indicated by a two-level analysis. An R-matrix analysis seems to indicate additional structure as well (OT72). The polarization of elastically scattered 3He has been studied at E(3He) = 18 MeV (MC72A). See also (LE67L; theor.). The α0 yield for E(3He) = 4.0 to 9.0 MeV shows fluctuations which are analyzed with a coherence width of 130 ± 20 keV (DA69I). These fluctuations continue at least to 11.8 MeV (BR69). For other work on these reactions see (72AJ02). See also (LO74F).
This reaction (and its mirror reaction 16O(6Li, 3He)19F) have been studied at E(6Li) = 24 MeV (BI71D, GA72A) and 35 and 36 MeV (PA72K). Observed states are displayed in Table 19.13 (in PDF or PS). The population of states at Ex = 4.593 ± 0.006, 4.71, 4.78 and 5.09 MeV, in addition to states previously reported in this reaction has been observed by (BI73B). For excitation functions see (BI73G) and (EN78). See also (WO76A, MA77G), (BA72P, FO73J) and (ST73K; theor.).
This reaction, 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 (HA76C).
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 19.26 (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*(4.558, 4.555) [Jπ = 5/2+, 3/2-]: these assignments disagree with the reports from the 16O(6Li, t)19Ne reaction [see reaction 4 and Table 19.13 (in PDF or PS)]. There is no evidence for a reported state at Ex = 4.78 MeV [see, however, reactions 4 and 14] (DA73P).
For a review of the threshold measurements see (72AJ02, FR76A). Excited states of 19Ne determined from γ-spectra are displayed in Table 19.25 (in PDF or PS): for τm and branching ratio measurements see Table 19.26 (in PDF or PS) (GI70E, IT71, LE77D). Earlier neutron measurements are displayed in Table 19.24 (in PDF or PS) of (72AJ02). The g-factor of 19Ne*(0.24) = -0.296 ± 0.003 (BL69B). See also (DE74B).
At E(3He) = 26 MeV, angular distributions of the triton groups to 19Ne*(0, 0.24, 1.54, 2.79) have been obtained by (SC70J); those to 19Ne*(0, 0.24) appear to proceed primarily via L = 0 and L = 2, respectively.
At E(6Li) = 34 MeV the transitions to 19Ne*(0, 0.24, 1.54, 2.79, 4.368 ± 0.010) have been studied (GA74D).
See (IN71C; unpublished thesis).
Alpha groups have been observed to 19Ne states with Ex < 10.6 MeV: see Tables 19.23 (in PDF or PS) and 19.27 (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 19.27 (in PDF or PS). Relative spectroscopic factors were also extracted. 19Ne*(0, 0.24, 1.54, 2.79) are identified as members of the K = 1/2+ rotational band [with 19Ne*(4.38) as the 7/2+ member: see, however, Table 19.13 (in PDF or PS)] and 19Ne*(0.28, 1.51, 1.62) with K = 1/2- band. Candidates for the 7/2- and 9/2- members of the K = 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 (GA70F). For lifetime and radiative decay measurements see Table 19.26 (in PDF or PS).
At Ep = 45 MeV triton groups are observed corresponding to 19Ne*(0, 0.24, 2.79, 4.03, 7.620 ± 0.025). The latter has an angular distribution [L = 0] 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 tritons to that state should be 2 (HA69H). At Ep = 40 MeV the ground-state angular distributions in this, and in the (p, 3He) mirror reaction, have been compared: see 19F (NA76N).