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USNDP

18Ne (1978AJ03)


(See Energy Level Diagrams for 18Ne)

GENERAL: See also (1972AJ02) and Table 18.22 [Table of Energy Levels] (in PDF or PS).

Model calculations: (1972EN03, 1974LO04).

Electromagnetic transitions: (1970SI1J, 1972EN03, 1974LO04, 1976SH04, 1977BR03, 1977SA13).

Special states: (1972EN03, 1972RA08).

Muon- and pion-induced capture and reactions (See also reaction 5.): (1972MI11, 1974LI1N, 1975LI04, 1976HE1G, 1977MA2Q, 1977RO1U).

Other theoretical calculations: (1970SI1J, 1972CA37, 1972RA08, 1973BE35, 1973GO1H, 1973PA1F, 1974RE03, 1974SH09, 1977SH13).

Ground state of 18Ne: (1974RE03, 1977BR03).
1. 18Ne(β+)18F Qm = 4.447

The half-life of 18Ne is 1687 ± 9 msec (1975HA21), 1669 ± 4 msec (1975AL27): the weighted mean of these two values is 1672 ± 5 msec. For earlier measurements see Table 18.24 (in PDF or PS) in (1972AJ02) and (1970AS1C, 1972HA58). The decay is to 18F*(0, 1.04, 1.70) with Jπ = 1+, 0+ and 1+; T = 0, 1 and 0, respectively: the branching ratios and log ft values are displayed in Table 18.20 (in PDF or PS). The mirror asymmetry δ = -0.86 ± 0.80% (1975AL27). See also (1972AJ02, 1975RA37) and (1972WI28, 1972WI1C, 1973LA03, 1973TO04, 1974WI1L, 1974WI02, 1975HA45, 1975WI1E, 1976LO01, 1977AZ02, 1977KU1E, 1977SZ03, 1977TO11; theor.).

2. 16O(3He, n)18Ne Qm = -3.196

Excitation energies of 18Ne states derived from neutron spectra and γ-ray measurements are displayed in Table 18.23 (in PDF or PS). Table 18.27 (in PDF or PS) in (1972AJ02) summarizes the earlier angular distribution studies for E(3He) to 17.8 MeV. Recent measurements include those by (1977EV01: E(3He) = 15 and 18 MeV; see Table 18.24 (in PDF or PS)) and (1975PE11: 18.3 MeV; n0, n1). Branching ratios and lifetimes of the first four excited states of 18Ne are shown in Table 18.24 (in PDF or PS). Comparison of the τm of 18Ne*(1.89), which leads to B(E2) = 52 ± 5 e2 · fm4, with that of 18O*(1.98), its analog, suggests the presence of two-body contributions to the E2 transition strength (1976MC02). See also (1974GO23) and (1972AJ02).

3. 16O(10B, 8Li)18Ne Qm = -18.951

At E(10B) = 100 MeV the first (d5/2)24+ state is preferentially excited (1977HA2E; prelim.). See also (1976TO1F).

4. 16O(12C, 10Be)18Ne Qm = -22.664

See (1971SC1F, 1972SC21).

5. 18O(π+, π-)18Ne Qm = -6.101

At Eπ+ = 139 MeV the transition to 18Ne(0) has been observed with dσ/dΩ(0°) = 1.78 ± 0.30 μb/sr (1977MA2Q).

6. 20Ne(p, t)18Ne Qm = -20.023

Transitions have been reported to fifteen states of 18Ne with Ex < 10 MeV: these are displayed in Table 18.23 (in PDF or PS) as are Jπ derived from DWBA analysis of angular distributions (1972PA02, 1974NE04). The 0+3 state, identified at Ex = 4.59 MeV appears to have a largely s21/2 configuration based on its large downward shift with respect to the analog state in 18O (1974NE04). See also (1972AJ02) and (1975OL03; theor.).