|
![]() |
![]() |
![]()
19Ne (1983AJ01)(See Energy Level Diagrams for 19Ne) GENERAL: See (1978AJ03) and Table 19.23 [Table of Energy Levels] (in PDF or PS). Nuclear models: (1978MA2H, 1978PE09, 1978PI06, 1979DA15, 1979MA27, 1979PE16, 1982KI02). Electromagnetic transitions: (1978PE09, 1978SC19, 1979MA27, 1979PE16). Special states: (1978MA2H, 1978PE09, 1978PI06, 1978SC19, 1979DA15, 1980OK01, 1982KI02). Astrophysical questions: (1977SI1D, 1979RA1C, 1979WO07). Applied topics: (1979AL1Q). Complex reactions involving 19Ne: (1978SH18, 1981GR08). Other topics: (1978MA2H, 1979BE1H, 1979MA27, 1979PE16, 1982KI02). Ground state of 19Ne: (1978MA54, 1979MA27, 1979SA41, 1979SA43).
μ0.239 = -0.740 ± 0.008 nm (1978LEZA).
The half-life of 19Ne is 17.22 ± 0.02 sec: see (1978AJ03). The decay is principally to 19Fg.s. [log ft = 3.237 ± 0.001 (1976AL07)]. The allowed nature of the decay to the ground state of 19F sets Jπ = 1/2+ for 19Neg.s.. Very weak branches are also observed to 19F*(0.110) [Jπ = 1/2-], (1.20 ± 0.20) × 10-2%, log ft = 7.05 ± 0.08 (1981AD05) and to 19F*(1.55) [Jπ = 3/2+], (2.1 ± 0.3) × 10-3%, log ft = 5.72 ± 0.06. The transition 19F*(1.55 → 0.20) invloves Eγ = 1356.92 ± 0.15 keV (1976AL07). See also (1982LOZZ) and (1978AJ03). 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 negligable contribution. The measured decay rate is roughly an order of magnitude smaller than predicted using standard wave functions (1981AD05). See also (1978KL1D, 1979SCZW, 1982SC1C, 1982SCZZ), (1977GA1E, 1977TE1B, 1978AJ03, 1978CA1H, 1978RA2A, 1978WE1J, 1979CA1K) and (1977KL09, 1980AN31, 1980OK01, 1981HA1Q; theor.).
See (1980KO02).
See (1978WU1C).
At E(12C) = 115 MeV 19Ne*(2.79, 4.64) are populated (1979PA06).
Excitation functions at θ = 40° and 90° have been measured for γ0→2, γ3→5 and γ6 [reaction (a)] for E(3He) = 3 to 19 MeV: see Table 19.25 (in PDF or PS) for a listing of the observed structures (1981WA1R). A resonance-like structure is reported at E(3He) ~ 9.5 MeV in the yield of neutron groups [reaction (b)] (1970AD02). Cross sections for production of 0.94, 1.04 and 1.08 MeV γ-rays [reaction (c)] have been measured for E(3He) = 2.6 to 4.0 MeV (1980HE06). The earlier work on reactions (c), (e) and (f) is summarized in (1978AJ03): reported resonances are shown in Table 19.25 (in PDF or PS). Analyzing powers for reactions (d) [to 17F*(0, 0.5)] and (f) [to 15O*(0, 6.18)] have been measured at E(pol. 3He) = 33 MeV (1980LU02, 1980LU03, 1981KA1L). Polarization measurements in reaction (g) are reported by (1981LE1F; 41 MeV). See also (1979KA1G, 1981RO1H) and 18F, 18Ne, 16O and 17F in (1982AJ01), 15O in (1981AJ01) and 12C in (1980AJ01).
Gamma transitions have been observed from the first six excited states of 19Ne: see Table 19.25 (in PDF or PS) in (1978AJ03) and Table 19.24 (in PDF or PS) here. At Eα = 41 MeV angular distributions are reported for the n0+1 group and for neutron groups to 19Ne*(1.55, 2.78, 4.20, 4.63, 5.43, 6.2, 6.80, 7.61, 8.42, 8.95, 9.23, 9.88, 10.40, 11.09, 12.49), many of which correspond to unresolved states. The relative spectroscopic factors, from a DW analysis, are 0.83, 1.62, 1.0, 2.92, 1.63 for 19Ne*(0, 0.24, 1.54, 2.79, 4.62, 5.4) (1981OV01).
This reaction (and the mirror reaction 16O(6Li, 3He)19F) have been studied at E(6Li) = 24, 35 and 36 MeV [see (1978AJ03)] and 46 MeV (1979MA26). Table 19.13 (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, ± 0.03] MeV (1979MA26).
Reaction (a) 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 (1976HA06). 19Ne*(4.63) is relatively strongly populated at E(11B) = 115 MeV [reaction (b)]. 19Ne*(2.79, 5.4, 9.8, 12.27) are also excited (1979RA10, 1981GO11) [see latter for Srel].
At E(12C) = 115 MeV 19Ne*(4.63) is strongly populated. 19Ne*(0.24, 1.54, 2.79, 9.8, 12.27) are also observed (1979GO17, 1979RA10, 1981GO11) [see the latter for Srel]. See also (1978CH15).
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 19.24 (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-, respectively] and that 19Ne*(4.55, 4.60) are the analogs of 19F*(4.558, 4.555) [Jπ = 5/2+, 3/2-, respectively]. There is no evidence for a reported state at Ex = 4.78 MeV (1973DA31).
Excited states of 19Ne determined from γ-spectra are displayed in Table 19.25 (in PDF or PS) of (1978AJ03). Branching ratio and τm measurements are summarized in Table 19.24 (in PDF or PS) here. Neutron measurements are shown in Table 19.24 (in PDF or PS) of (1972AJ02). For the g-factor of 19Ne*(0.24) see Table 19.23 (in PDF or PS). See also (1979WI1N, 1980HU1J) and 20Ne.
At E(3He) = 26 MeV angular distributions of the triton groups to 19Ne*(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.
At E(6Li) = 34 MeV the transitions to 19Ne*(0, 0.24, 1.54, 2.79, 4.368 ± 0.010) have been studied (1974GA11).
See 20Ne.
See (1972AJ02).
See (1978AJ03).
Alpha groups have been observed to 19Ne states with Ex < 10.6 MeV: see Tables 19.22 (in PDF or PS) and 19.26 (in PDF or PS). Angular distributions have been measured for E(3He) = 10 to 35 MeV: see (1972AJ02). DWBA analysis of the strongest transitions leads to the l and Jπ values shown in Table 19.26 (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 19.23 (in PDF or PS)] 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). For lifetime and radiative measurements see Table 19.24 (in PDF or PS).
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 dominant 5p-2h configuration. 19Ne*(5.09) has π = + and its J is consistent with the previous value of 5/2 (1978FO26, 1979FO06). At Ep = 45 MeV the triton group to a state with Ex = 7.620 ± 0.025 has an angular distribution [L = 0] which is similar to that for 19F*(7.66): both are thought to be 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 (1969HA38). 19Ne*(0, 2.79) are also populated: see (1978AJ03).
|
![]() |