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USNDP

20O (1983AJ01)


(See Energy Level Diagrams for 20O)

GENERAL: See also (1978AJ03) and Table 20.1 [Table of Energy Levels] (in PDF or PS).

Model calculations: (1977GR16).

Special states: (1977GR16).

Astrophysical questions: (1979WO07).

Other topics: (1977GR16, 1978RA1J, 1979BE1H).

1. 20O(β-)20F Qm = 3.816

20O decays to 20F*(1.06) [Jπ = 1+] with a half-life of 13.51 ± 0.05 sec (weighted mean of (1970MA42, 1974AL09)), log ft = 3.75 ± 0.01. Upper limits for the branching to other states of 20F are shown in Table 20.2 (in PDF or PS) of (1978AJ03) and in Table IV of (1974AL09). See also (1981KA32; theor.).

2. 18O(t, p)20O Qm = 3.079

Observed proton groups are displayed in Table 20.2 (in PDF or PS). The first excited state, 20O*(1.67) has τm = 10.7 ± 0.4 psec (1980RU01) [M2|E2| = 1.76 ± 0.07 W.u.], 9.8 ± 0.7 psec (1977HE12); g = -0.352 ± 0.015 [(1980RU01) and see (1978AJ03)]. 20O*(4.07) decays to 20O*(0, 1.67) with branchings of 26 ± 4 and 74 ± 4 %. The p-γ angular correlations lead to J = 2; the strength of the transition favors π = +[δ(E2/M1) = -0.18 ± 0.08 for the 2+ → 2+ transition]. 20O*(4.46) and 20O*(5.39) decay primarily via 20O*(1.67); the direct ground-state decay is < 4% for the first and < 7% for the second of these states. The angular correlations are essentially isotropic, favoring Jπ = 0+. The transition 20O*(5.39 → 4.07) is not observed: the upper limit is 8% (1981YO03).

3. 18O(α, 2p)20O Qm = -16.735

At Eα = 65 MeV the population of 20O*(0, 1.67, 3.57) and of states at 7.78, 8.78 and 10.2 [± 0.1] MeV are reported (1978JA10). See also (1978BI1N).

4. 18O(18O, 16O)20O Qm = -0.628 (For other reactions leading to 20O see (1978AJ03).)

Angular distributions have been measured to 20O*(0, 1.67) at E(18O) = 24 to 36 MeV (1977KA21) and to 20O*(0, 1.67, 3.57, 4.07, 4.46) (1979KU01). A FRDWBA analysis shows L = 0 for the transitions to 20O*(0, 4.46) but underestimates the absolute cross sections by an order of magnitude (1979KU01).