(See Energy Level Diagrams for 19Ne)
Astrophysical questions: (1970BA1M).
The half-life is 17.40 ± 0.04 sec: see Table 19.22 (in PDF or PS) (1962EA02, 1968GO10). The decay is to 19F(0) (1954JO21). log ft = 3.23 †. See also (1965HA31, 1970ST04). The allowed nature of the decay sets Jπ = 1/2+ for 19Ne(0).
† B.A. Zimmerman, private communication.
A test of time reversal invariance and a measurement of positron and neutrino asymmetry has been made by (1969CA14). See also (1959AL1E, 1959AL10, 1961JO03, 1963CO22, 1967CA1M, 1967CO1D, 1969CA1H) and (1965GA1D, 1966MI1F, 1967CA1N, 1969LE1D, 1969SU15, 1970KO41, 1970MC23, 1970PR1G, 1971WE1F; theor.).
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 (1959BR79, 1961SI09). The capture cross section at the 2.40 MeV resonance (reaction (a)) is < 0.8 μb (1959BR79). 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+ (1967RO10). A resonance-like structure is also reported at E(3He) ≈ 9.5 MeV in the yields of neutron groups (reaction (b)) (1970AD02).
The elastic scattering (reaction (d)) and the α0 yield (reaction (e)) have been studied for E(3He) = 3.2 to 7.0 MeV by (1971OT1C). They report a state at Ex = 11.51 MeV [E(3He) = 3.65 MeV] with Jπ = 3/2- or (1/2-), Γc.m. = 24 keV. In addition, two states at Ex = 12.23 and 12.50 MeV [E(3He) = 4.50 and 4.82 MeV], Jπ = 5/2+ and 7/2+, Γc.m. = 200 and 150 keV respectively, are indicated by the work of (1971OT1C). See also (1970OT1B, 1970WE1K).
For reaction (b), see also (1961DU02: 3.4 to 5.6 MeV), (1961TO03: 3.9 to 5.7 MeV), (1968TO09: 9.1 to 10.4 MeV) and (1964BR1G, 1965BR1B: 11 to 29 MeV). For reaction (c), see also (1966GO1E: 2.0 to 5.5 MeV), (1966HA21: 3.0 to 9.5 MeV) and (1964BR1G, 1965BR1B: 11 to 29 MeV). For reaction (d), see also (1965AL05: 8.1 to 10 MeV) and (1969BR07: 9.8 to 11.7 MeV). For polarization measurements, see (1970MC1F, 1971MC1M). For reaction (e), see also (1966HA21: 3 to 9.5 MeV), (1959HI73: 5.6 to 5.9 MeV), (1965AL05: 8.0 to 10.0 MeV). For reaction (f) see (1967ES02) and for reaction (g) see (1964BR1G, 1965BR1B). See also (1965JI1A, 1966MA1R, 1969PA1C).
This reaction (and its mirror reaction 16O(6Li, 3He)19F) have been studied at E(6Li) = 24 MeV: see reaction 12 in 19F and Table 19.11 (in PDF or PS) for a summary of the results (1971BI06). See also (1971GA1H, 1971GO1B).
At E(3He) = 3.1 MeV, neutron groups have been observed corresponding to states at Ex = 0.24 ± 0.07, 1.55 ± 0.06, 2.78 ± 0.05, (3.70 ± 0.04), 4.01 ± 0.02, 4.13 ± 0.03, 4.36 ± 0.03, 4.54 ± 0.03, 4.61 ± 0.04, 4.69 ± 0.03 and 5.09 ± 0.03 MeV (1968GU07). Angular distributions have been obtained for n0+1+2, n3+4+5 and n6. The latter suggest L = 2 and Jπ = (1/2, 3/2, 7/2, 9/2)+ for 19Ne*(2.79) (1968GU07).
Excited states of 19Ne determined from neutron threshold measurements and the measurement of neutron and γ spectra are displayed in Table 19.24 (in PDF or PS) (1955MA84, 1962FR09, 1963GI09, 1965WE05, 1970GI09). The radiative decay of the first six states has been studied by (1970GI09) who also studied the lifetimes and Jπ of 19Ne*(1.51, 1.54, 1.62, 2.79): see Table 19.23 (in PDF or PS). See also (1957BA09). The g-factor of 19Ne*(0.24) = -0.296 ± 0.003 (1969BL02). An angular distribution measurement is reported at Ep = 6.8 MeV (1967DR08; n0+1+2+3?). See also (1964ST1C). Astrophysical considerations are discussed in (1969BA1N). See also (1962EA02).
At E(3He) = 26 MeV, angular distributions of the triton groups to 19Ne*(0, 0.24, 1.54, 2.79) have been obtained by (1970SC05); those to 19Ne*(0, 0.24) appear to proceed primarily via L = 0 and L = 2, respectively.
Alpha groups have been observed to many states of 19Ne with 0 < Ex < 9.7 MeV: see Table 19.25 (in PDF or PS) (1967GR04, 1970GA18, 1972HA03). Angular distributions have been measured at E(3He) = 10 MeV (1969BA62; α0, α6), 15 MeV (1969BA62; α6), 15 MeV (1970GA18; α to 0 < Ex < 6.87), 18 MeV (1972HA03) and 35 MeV (1971AR1E). DWBA analysis of the strongest transitions leads to the l and Jπ values shown in Table 19.25 (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] and 19Ne*(0.28, 1.51, 1.62) with the 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 (1970GA18).
The mean lifetimes, τm, of 19Ne*(0.24, 0.28) are, respectively, 26.6 ± 1.2 nsec (1967BE14) and 61.4 ± 3.0 psec (1970BH02). 19Ne*(0.28) decays to the ground state by E1 emission: B(E1) = (1.06 ± 0.05) × 10-3 W.u. The ratio of this value to that for the analog state in 19F is 0.95 ± 0.06 (1970BH02). The γ-decay of seven states of 19Ne has been studied by (1967OL05): see Table 19.23 (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 = 3/2+; T = 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 (1969HA38).