A=18O (1983AJ01)

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¹⁸O (1983AJ01)

(See Energy Level Diagrams for ¹⁸O)

GENERAL: See also (1978AJ03) and Table 18.2 [Table of Energy Levels] (in PDF or PS).

Shell model: (1977AN1P, 1977GR16, 1977SO11, 1977ZH1A, 1978CH26, 1978CO08, 1978DA1N, 1978MA2H, 1978MO06, 1978RU02, 1979DA15, 1979WU06, 1980GO01, 1980KU05, 1980MA18, 1981EL1D, 1982KI02, 1982OL01).

Cluster, collective and deformed models: (1977BU22, 1978BU03, 1978CH26, 1978PI1E, 1978RU02, 1978SA15, 1979SA31, 1980BA1T, 1980ZH01).

Electromagnetic transitions and giant resonances: (1976MC1G, 1977BU22, 1977HA1Z, 1978BU03, 1978MO06, 1978SA15, 1979KO07, 1979SA31, 1980BA1T, 1980BR08, 1980BR09, 1980KO1L, 1980KU05, 1980MI1G, 1982LA26).

Special states: (1977AN1P, 1977GR16, 1977HE18, 1977SH18, 1978AN1P, 1978BA10, 1978BU03, 1978EN1D, 1978FO18, 1978KR1G, 1978MA2H, 1978MO06, 1978PI1E, 1978SA15, 1978ZA04, 1979BA35, 1979CHZL, 1979DA15, 1979KO07, 1979KU04, 1979SA31, 1979ZA07, 1980GO01, 1980MA18, 1980SH1K, 1981AR1D, 1981EL1D, 1981SO03, 1982KI02, 1982NA03, 1982ZH1D).

Astrophysical questions: (1977AU1E, 1977CA1K, 1977CL1C, 1977CO1W, 1977DE1N, 1977DI1C, 1977EN1B, 1977SI1F, 1977TR1D, 1977WA1P, 1978CL1F, 1978LE1W, 1978PO1B, 1978TR05, 1978TR1C, 1979CH1T, 1979GU1D, 1979JA1M, 1979LA1H, 1979LE1F, 1979PE1E, 1979RO1A, 1979TU1A, 1979WO07, 1980CL1B, 1980MC1G, 1980PE1F, 1980WA1M, 1981BL1J, 1981GU1D, 1981PE1F, 1981WE1F, 1981WI1D, 1981WI1G, 1981WO1B).

Applied work: (1977EP1A, 1977GR1L, 1977SH1E, 1978AM1D, 1978EM1A, 1978HA2B, 1979JU1D, 1979LE1L, 1980SI1G, 1981BU1B).

Complex reactions involving ¹⁸O: (1977LO1K, 1978FO05, 1978FR19, 1978FR1B, 1978KO01, 1978LI1F, 1978SH18, 1978SP1D, 1978TA15, 1979AL22, 1979FE06, 1979HE1D, 1979LA16, 1979PO08, 1979SA27, 1980BR09, 1980OLZW, 1981GR08).

Muon and neutrino capture and reactions: (1977BA1P, 1980BA36).

Pion capture and reactions (See also reaction 29.): (1977AL2B, 1977BA2G, 1977BO1E, 1977EI1A, 1977LE16, 1977MI1E, 1977PE12, 1977SP1B, 1977ST27, 1978IV01, 1978JA13, 1978LE1Y, 1978LU09, 1978OS02, 1978SE07, 1978SP07, 1979AB1H, 1979AL1J, 1979AR1M, 1979CO1H, 1979GO1X, 1979GR18, 1979IN1A, 1979IV03, 1979LE1Q, 1979LU09, 1979MO2C, 1979OS05, 1979SE08, 1980AR1E, 1980AS1A, 1980BR08, 1980BR09, 1980DE24, 1980FR09, 1980GE09, 1980JO06, 1980KA1L, 1980LE04, 1980LI1H, 1980LI1L, 1980NA1D, 1980SA04, 1980SC24, 1980TH01, 1981BE31, 1981FR17, 1981KA1N, 1981LI04, 1981LI1J, 1981LI1L, 1981LI1M, 1981LI1Q, 1981LI1W, 1981MI09, 1981OS1F, 1981RI1A, 1981TH1B, 1982DE1K, 1982GR02, 1982GR1F, 1982IN1A, 1982TH1C).

K-mesons and other meson interactions: (1980DO1E, 1981BA1H, 1981MA27, 1982BA1R).

Anti-proton interactions: (1977BA1W, 1977WE1E, 1978PO02).

Other topics: (1977AN1P, 1977GR16, 1977SH18, 1977SO11, 1978AN1P, 1978CO08, 1978DA03, 1978EN1D, 1978GA1C, 1978GO1U, 1978KR1G, 1978MA2H, 1978SH1B, 1979BA35, 1979BR30, 1979CO10, 1979CO09, 1979GO1W, 1979HE1F, 1979KU04, 1979WU06, 1980GO01, 1980ZH01, 1981AR1D, 1981BE31, 1981EL1D, 1981MA27, 1981SH17, 1981SO03, 1982BA1R, 1982KI02, 1982LA02, 1982NA03).

Ground and 1.98 MeV states of ¹⁸O: (1976MC1G, 1977BA2E, 1977GO18, 1977HA1Z, 1978AN07, 1978CH26, 1978FO05, 1978HE1D, 1978LE1X, 1978RU02, 1978SM02, 1978TA09, 1979BR17, 1979BR30, 1979KO07, 1979KO28, 1979SA27, 1979WU06, 1980BA36, 1980BR09, 1980BR13, 1980DE24, 1980MA18, 1980MO05, 1981AR1D, 1981AV02, 1981SI1B, 1982LA02, 1982ZH1D).

< r² >^1/2 = 2.784 ± 0.020 fm: see reaction 28.

¹⁸O*(1.98):

|g| = 0.287 ± 0.015 (1976AS04);

g = -0.35 ± 0.04 (1975FO03, 1975SP03);

Q = -0.023 ± 0.021 b · e (1979FE06) [(1981SP07) adopts -0.02 ± 0.03 b · e];

B(E2; 0⁺ → 2⁺) = 39.0 ± 1.8 e² · fm⁴ (1979FE06) (Assuming destructive interference

(see (1979KO28)) from the coupling through the second 2⁺ state. See however the discussion in (1982BA06).);

= 44.8 ± 1.3 e² · fm⁴ (1982NO04);

= 47.6 ± 1.0 e² · fm⁴ (1982BA06).

1. ⁹Be(⁹Be, ⁹Be)⁹Be E_b = 23.4790

Yield measurements are reported at a number of energies for E(⁹Be) = 3.0 to 16.0 MeV (1977YO02).

2. (a) ¹¹B(⁷Li, p)¹⁷N Q_m = 8.417 E_b = 24.359
(b) ¹¹B(⁷Li, d)¹⁶N Q_m = 4.749
(c) ¹¹B(⁷Li, t)¹⁵N Q_m = 8.525
(d) ¹¹B(⁷Li, α)¹⁴C Q_m = 18.131

Cross sections to various of the final states have been measured at E(⁷Li) = 5.00 MeV (1966MC05).

3. ¹²C(⁷Li, p)¹⁸O Q_m = 8.402

Observed proton groups are displayed in Table 18.4 (in PDF or PS). See also (1978AJ03). (1978FO18) suggests that an unresolved 0⁺ state at E_x = 7.11 MeV and the 2⁺, 4⁺ and 6⁺ states at 3.21, 10.29 and 12.53 MeV are 6p - 4h states.

4. ¹²C(²⁰Ne, ¹⁴O)¹⁸O Q_m = 14.2683

See (1979OR01).

5. ¹³C(⁷Li, d)¹⁸O Q_m = 5.680

See (1978AJ03).

6. (a) ¹³C(⁹Be, α)¹⁸O Q_m = 12.8311
(b) ¹³C(¹³C, 2α)¹⁸O Q_m = 2.1832

Angular distributions for α₀ and α₁ [reaction (a)] have been measured at E(⁹Be) = 27.9 MeV (1980BO21). For yields see (1981PO05). For reaction (b) see (1982CH05).

7. ¹³C(¹⁷O, ¹²C)¹⁸O Q_m = 3.098

Angular distributions for the transitions to ¹⁸O*(0, 1.98) are reported at E(¹⁷O) = 29.8 and 32.3 MeV (1978CH16).

8. (a) ¹⁴C(α, γ)¹⁸O Q_m = 6.2279
(b) ¹⁴C(α, α)¹⁴C E_b = 6.2279

Resonances in the yields of capture γ-rays [reaction (a)] are observed at E_α = 1.14, 1.79, 2.09, 2.33, 2.44, 2.55 and 2.64 MeV: see (1978AJ03) and (1982GA1D). Gamma-ray angular distribution and correlation measurements lead to J^π = 4⁺, 1^-, 1^- and 5^- for ¹⁸O*(7.12, 7.62, 8.04, 8.13), as well as to J^π assignments for lower states involved in the cascade decay: see Tables 18.3 (in PDF or PS) and 18.5 (in PDF or PS). See also (1980SP1B; astrophys.) and (1978AJ03).

Observed anomalies in the scattering [reaction(b)] for E_α = 2 to 8.2 MeV are shown in Table 18.5 (in PDF or PS). The yield of elastic scattering has been measured up to E_α = 16.5 MeV (1970MO13). See also ¹⁴C in (1981AJ01).

9. ¹⁴C(α, n)¹⁷O Q_m = -1.8167 E_b = 6.2279

The relative neutron yield has been measured for E_α = 2.3 to 8.5 MeV: the parameters of observed resonances are displayed in Table 18.5 (in PDF or PS).

10. ¹⁴C(⁶Li, d)¹⁸O Q_m = 4.7544

At E(⁶Li) = 34 MeV the spectra are dominated by the groups to ¹⁸O*(5.10, 7.12) [J^π = 3^-, 4⁺]. Angular distributions, analyzed in terms of HF and FRDWBA, are reported for ¹⁸O*(0, 1.98, 3.55 + 3.63, 3.92, 4.46, 5.10, 5.26 + 5.34, 6.2, 7.12, 7.62, 7.86, 8.14, 8.29, 8.9, 10.12, 10.30, 11.39 + 11.41, 11.62 + 11.69, 12.04, 12.25 + 12.23, 12.53, 14.6, 17.0). Differential cross sections are also reported for ¹⁸O*(9.36 + 9.41, 10.91 + 10.99, 11.13, 12.9). J^π = 4⁺, 2⁺, 2⁺, (4⁺), and (4⁺) are suggested for ¹⁸O*(7.86, 8.9, 12.04, 14.6, 17.0). The results indicate that ¹⁸O*(5.26, 7.12, 11.69) are the 2⁺, 4⁺ and 6⁺ members of the K^π = 0⁺₂ rotational band based on ¹⁸O*(3.63) (1981CU07). See also (1982AR1F).

11. ¹⁴C(⁷Li, t)¹⁸O Q_m = 3.761

At E(⁷Li) = 20.4 MeV, triton groups are observed corresponding to a number of states of ¹⁸O with E_x < 12.6 MeV. Angular distributions were obtained for some of these, including ¹⁸O*(0, 1.98, 7.12, 11.69) with J^π = 0⁺, 2⁺, 4⁺, 6⁺. The latter two are the most strongly populated in this reaction: they appear to be part of the ground-state rotational band (1970MO17). See also (1978FO16; theor.).

12. ¹⁴C(¹⁶O, ¹²C)¹⁸O Q_m = -0.9341

Angular distributions at E(¹⁶O) = 20, 25 and 30 MeV have been studied by (1973SC24, 1975SC35). See also (1978KA23; theor.).

13. ¹⁵N(t, α)¹⁴C Q_m = 9.6066 E_b = 15.8345

See (1978AJ03).

14. (a) ¹⁵N(α, p)¹⁸O Q_m = -3.9796
(b) ¹⁵N(⁶Li, ³He)¹⁸O Q_m = 0.041

For reaction (a) see ¹⁹F. The work reported in (1978AJ03) for reaction (b) has not been published.

15. ¹⁵N(¹³C, ¹⁰B)¹⁸O Q_m = -8.0421

At E(¹³C) = 105 MeV ¹⁸O*(11.06, 11.79) [J^π = (7^-), (6^-)] are relatively strongly populated (1979RA10). See also (1977FO1E).

16. ¹⁶O(t, p)¹⁸O Q_m = 3.7069

Proton groups corresponding to states of ¹⁸O are displayed in Table 18.6 (in PDF or PS) (1981CO13). Angular distributions have been measured at many energies up to E_t = 15 MeV: see (1978AJ03) and Table 18.6 (in PDF or PS). Analysis of spectroscopic factors suggest that ¹⁸O*(5.34) [0⁺₃] is largely (s_1/2)² while ¹⁸O*(3.63) [0⁺₂] has a dominantly collective nature as does ¹⁸O*(5.25) [2⁺₃] (1974FO14, 1976LA13): see (1976LA13) for a general discussion of the properties of the states of ¹⁸O. Lifetime measurements are reported in Table 18.4 (in PDF or PS) of (1978AJ03). See also (1977CI1D, 1979PI01) and (1977PI10, 1978PI10, 1979PI10; theor.).

17. ¹⁶O(α, 2p)¹⁸O Q_m = -16.1071

At E_α = 65 MeV, the angular distribution to ¹⁸O*(3.55) [J^π = 4⁺] has been studied. In addition ¹⁸O*(8.04, 9.15, 10.3) are also populated (1978JA10).

18. (a) ¹⁶O(¹⁰B, ⁸B)¹⁸O Q_m = -14.824
(b) ¹⁶O(¹²C, ¹⁰C)¹⁸O Q_m = -19.6569
(c) ¹⁶O(¹³C, ¹¹C)¹⁸O Q_m = -11.479
(d) ¹⁶O(¹⁴C, ¹²C)¹⁸O Q_m = -0.9341

At E(¹⁰B) = 100 MeV, reaction (a) preferentially populates ¹⁸O*(3.55) [first (d_5/2)²_4⁺ state]. ¹⁸O*(1.98, 5.26, 7.12, 8.0, 8.3, 9.1) are also populated (1978HA10). For reaction (b) see (1978AJ03). At E(¹³C) = 105 MeV [reaction (c)] the angular distribution to ¹⁸O*(3.55) has been measured (1979RA10, 1980PR09). For reaction (d) see (1979HAYV).

19. ¹⁷O(n, γ)¹⁸O Q_m = 8.0446

The thermal capture cross section of ¹⁷O is 538 ± 65 μb (1979LOZK; prelim.).

20. ¹⁷O(n, n)¹⁷O E_b = 8.0446

The scattering amplitude (bound) a = 5.62 ± 0.45 fm, σ_free = 3.55 ± 0.25 b (1979KO26). See also (1981MA16) and (1978AJ03, 1981MUZQ).

21. ¹⁷O(n, p)¹⁷N Q_m = -7.898 E_b = 8.0446

See (1978AJ03).

22. ¹⁷O(n, α)¹⁴C Q_m = 1.8167 E_b = 8.0446

The thermal cross section is 235 ± 10 mb: see (1973MU14).

23. ¹⁷O(d, p)¹⁸O Q_m = 5.8199

Observed proton groups are displayed in Table 18.7 (in PDF or PS). Proton-γ coincidence measurements are shown in Table 18.3 (in PDF or PS). See also (1977PE08, 1978AJ03) and (1979SA31; theor.).

24. (a) ¹⁷O(¹²C, ¹¹C)¹⁸O Q_m = -10.677
(b) ¹⁷O(¹⁷O, ¹⁶O)¹⁸O Q_m = 3.900

Angular distributions [reaction (a)] involving ¹⁸O*(0, 1.98, 3.55) have been studied at E(¹²C) = 115 MeV (1980PR09). For reaction (b) see (1972AJ02).

25. ¹⁸N(β^-)¹⁸O Q_m = 14.03

The transitions observed in the β^- decay are displayed in Table 18.8 (in PDF or PS) (1982OL01).

26. (a) ¹⁸O(γ, n)¹⁷O Q_m = -8.0446
(b) ¹⁸O(γ, 2n)¹⁶O Q_m = -12.1889
(c) ¹⁸O(γ, p)¹⁷N Q_m = -15.942
(d) ¹⁸O(γ, t)¹⁵N Q_m = -15.8345
(e) ¹⁸O(γ, α)¹⁴C Q_m = -6.2279

The cross sections for the (γ, p), (γ, n), (γ, 2n) and (γ, tot) [tot = total absorption] have been measured with monoenergetic photons to 42 MeV: observed resonances are displayed in Table 18.9 (in PDF or PS). All three of the partial cross sections have substantial strength in the giant resonance region; the (γ, 2n) cross section is a significant fraction of σ(γ, tot) and is even larger than σ(γ, p). Above the GDR the partial cross sections decrease but the integrated σ(γ, tot) between 29 and 42 MeV is about one-third of the value integrated from threshold to 42 MeV. The relative strengths of partial cross sections leads to the T assignments shown in Table 18.8 (in PDF or PS). The T_< and T_> components of the ¹⁸O photo absorption cross section are also derived (1979WO04). Structures in the (γ, α₀) cross section are reported at E_x = 18.2, 20.9, 22.1 and 24.2 MeV (1982BA03; E_brems.). See also (1980PY01). The decay of the GDR to ¹⁴C, ¹⁵N, ¹⁶O, ¹⁷N and ¹⁷O states has been studied by (1976BA41, 1982BA03). See also (1978AJ03) for the earlier work, (1979BE1X) and (1981BA04; theor.).

27. ¹⁸O(γ, γ)¹⁸O

The γ₀ width of ¹⁸O*(6.20) is 0.18 ± 0.03 eV, assuming Γ_γ₀/Γ = 0.88; E_x = 6202.7 ± 0.8 keV (1974HA15).

28. ¹⁸O(e, e)¹⁸O

The ¹⁸O charge radius, < r² >^1/2 = 2.784 ± 0.020 fm, based on studies of the elastic charge form factors for E_e = 70 to 370 MeV, the resulting determination of the difference in the ¹⁸O and ¹⁶O radii [+0.074 ± 0.005 fm] (1979MI09) and the rms radius of ¹⁶O quoted in (1982AJ01). [The Δr from muon studies is 0.076 ± 0.005 fm (1980BA36)]. See also (1982NO04). For earlier values see (1978AJ03).

Inelastic scattering has been reported to ¹⁸O*(1.98, 3.55, 3.63, 3.92, 5.10, 5.26, 5.34, 7.12, 7.86) [see (1978AJ03, 1982NO04)], to states at E_x = 11.6, 12.1, 12.5, 14.8, 15.8, 18.0 and 20.8 MeV (most probable assignments 2⁺) [or (2⁺, 4⁺) for the 11.6 and 12.5 MeV levels] (1980AN17: E_e = 80 to 166 MeV). [Several weak and broad bumps are also reported at E_x = 31.2, 34.0 and 36.8 MeV, and some transverse contributions are suggested in the range 14.8 to 21.8 MeV (1980AN17). In addition to determining the form factors at 90° and 160° in the range 0.6 ≤ q ≤ 2.7 fm^-1 for the 0⁺ states ¹⁸O*(3.63, 5.34), the 2⁺ states ¹⁸O*(1.98, 3.92, 5.26) and the 4⁺ states ¹⁸O*(3.55, 7.12, 7.86). (1982NO04) report transition charge density parameters for ¹⁸O*(1.98, 3.92, 5.26, 7.11) as well as B(EL; 0⁺₁ → L⁺). The B(E2) are 44.8 ± 1.3, 22.2 ± 1.0 and 28.3 ± 1.5 e² · fm⁴ for ¹⁸O*(1.98, 3.92, 5.26) and the B(E4) = (9.04 ± 0.90) × 10² and (1.31 ± 0.06) × 10⁴ e² · fm⁸ for ¹⁸O*(3.55, 7.12) (1982NO04). At E_e = 45 to 59 MeV sharp states are observed at E_x = 16.38 and 18.86 ± 0.01 MeV (≤ 30 and ≤ 60 keV). It is suggested that both are T = 2 states with the first the analog of the ground state of ¹⁸N. B(M2)(uparrow) = 58 ± 8 μ²_k · fm² and B(M1)(uparrow) = 0.28 ± 0.04 μ²_k for ¹⁸O*(16.38, 18.86). In addition a structure at E_x = 23.7 MeV is also reported (1980AN18). See also (1981RI1A, 1982BE1J, 1982RI1B) and (1981PE1C; theor.).

29. ¹⁸O(π, π)¹⁸O

Angular distributions for the elastic scattering and the inelastic scattering to ¹⁸O*(1.98) have been studied at E_π^± = 29.2 MeV (1979JO08), 163 MeV (1978JA13; also to ¹⁸O*(5.10)), 180 MeV (1978LU09) and 164 and 230 MeV (1978IV01, 1979IV03; also to ¹⁸O*(5.10)). See also (1982SEZZ). The ratio σ(π^-)/σ(π⁺) for the 2⁺ state is 1.86 ± 0.16 while for the 3^- state it is 0.89 ± 0.06. An optical model analysis leads to < r²_n >^1/2 - < r²_p >^1/2 = 0.03 ± 0.03 fm (1979IV03). (1979JO08) report < r²_n >^1/2 = 2.81 ± 0.03 fm. The inclusive inelastic scattering and true absorption cross sections have been measured at E_π^± = 165 MeV and E_π⁺ = 315 MeV (1980NA10). See also the "GENERAL" section here.

30. ¹⁸O(n, n)¹⁸O

Angular distributions have been measured at E_n = 24 MeV (1980GR15; n₀, n₁ and n to ¹⁸O*(5.10): deformation and isospin effects are discussed). See also Table 18.8 (in PDF or PS) in (1972AJ02) and (1981DI1C; theor.).

31. ¹⁸O(p, p)¹⁸O

Angular distributions have been measured for E_p = 0.84 to 135 MeV: see (1978AJ03) and (1979MU05; 6.1 - 16.6 MeV; p₀, p₁ [and p to ¹⁸O*(3.55, 5.09, 7.11) at 16.2 MeV]), (1980FA06, 1980FA07; 17.7 - 44.1 MeV; p₀), (1978NO1G, 1980KE1C, 1981KE1B; 135 MeV; all abstracts) and (1981GL1B; E_{pol. p} = 800 MeV; p₀, p₁, p₄, p₅, p₆ and p to ¹⁸O*(7.12)).

At E_p = 24.5 MeV (1974ES02) have studied the angular distributions of the proton groups to ¹⁸O*(1.98, 3.55, 3.63, 3.92, 4.46, 5.10, 5.26, 5.53, 7.12): a modified DWBA analysis leads to J^π = 2⁺, 4⁺, 0⁺, 2⁺, 1^-, 3^-, 2⁺, 2^- and 4⁺ for these states. A coupled-channels calculation suggests β₂ = 0.37 ± 0.03, 0.56 ± 0.06 and 0.18 ± 0.04 for ¹⁸O*(1.98, 5.10, 7.12). Such calculations also support evidence for a rotational band involving ¹⁸O*(0, 1.98, 7.12). The 3^- state at 5.10 MeV is strongly excited and collective in nature: B(E3) = 1120 e² · fm⁶. For ¹⁸O*(1.98, 3.92, 5.26), B(E2) = 45, 8.3 and 24 e² · fm⁴ (1974ES02).

¹⁸O*(1.98) has |g| = 0.287 ± 0.015 [τ_m = 2.99 ± 0.12 psec] (1976AS04). ¹⁸O*(3.55) has |g| = 0.62 ± 0.10 suggesting a mainly (d_5/2)² configuration for this state (1974BE63). The work on T = 2 states reported earlier has not been published: see (1978AJ03). For polarization measurements see ¹⁹F. See also (1978DI13) and (1978KU03, 1978MO06, 1981PI11; theor.).

32. ¹⁸O(d, d)¹⁸O

Angular distributions of elastically scattered deuterons have been measured for E_d = 7.0 to 15.0 MeV (also d₁ at 15 MeV): see (1978AJ03) and (1979ST21; E_d-bar ≈ 10 MeV; d₀). See (1972AJ02) for the population of other states of ¹⁸O and see ²⁰F.

33. ¹⁸O(t, t)¹⁸O

The elastic scattering has been studied at E_t = 6.4 and 7.2 MeV (1964PU01).

34. ¹⁸O(³He, ³He)¹⁸O

The elastic scattering has been studied at E(³He) = 11.0 to 17.3 MeV [see (1972AJ02)] and at E(pol. ³He) = 33 MeV (1981LE1H; also inelastic to ¹⁸O*(1.98) and analyzing powers) and E(³He) = 41 MeV (1980TR02). See also (1981CO15; theor.).

35. ¹⁸O(α, α)¹⁸O

Angular distributions of many α-groups have been measured in the range E_α = 21 to 40.5 MeV: see (1978AJ03). The transitions to ¹⁸O*(4.46, 5.10) are L = 1 and 3, respectively, fixing J^π = 1^- and 3^- for these states (1966HA19). Measurements of α-groups near 180° for E_α = 20.0 to 23.4 MeV confirm assignments of natural parity for ¹⁸O*(1.98, 3.55, 3.63, 3.92, 4.46, 5.10, 5.26, 5.34, 6.20, 6.40, 7.12, 7.62, 7.86, 8.22, 8.29, 8.82, 8.96, 9.03, 9.10, 9.36, 9.41, 9.68, 9.72 ± 0.03, 9.88, 10.12, 10.29, 10.40, 11.62, 11.69). The levels at E_x = 5.38, 8.48 and 8.64 MeV were not observed, and those at 5.53, 6.35 and 6.88 MeV were populated weakly indicating unnatural parity: J^π = 3⁺ and 2^- respectively for ¹⁸O*(5.38, 5.53) (1971OL06).

Alpha-gamma correlation measurements involving ¹⁸O states below E_x = 6.4 MeV [see Table 18.3 (in PDF or PS)] lead to J^π = 1^- and 3^- for ¹⁸O*(6.20, 6.40). Other J^π values agree with previous assignments. The transitions 3.92 → 1.98 and 5.26 → 1.98 are almost pure M1 (1971BE45). For τ_m measurements see Table 18.4 (in PDF or PS) in (1978AJ03). ¹⁸O*(1.98) has a negative g-factor (1975FO03), |g| = 0.35 ± 0.04 (1975SP03). See also (1977MA2E, 1979KN1F) and (1981CA1E, 1981LA1G; theor.).

36. (a) ¹⁸O(⁶Li, ⁶Li)¹⁸O
(b) ¹⁸O(⁷Li, ⁷Li)¹⁸O

An elastic angular distribution has been measured at E(⁶Li) = 32 MeV (1975WH01). For reaction (b) see (1972AJ02).

37. ¹⁸O(⁹Be, ⁹Be)¹⁸O

See (1971KN05).

38. (a) ¹⁸O(¹⁰B, ¹⁰B)¹⁸O
(b) ¹⁸O(¹¹B, ¹¹B)¹⁸O

An elastic angular distribution has been reported at E(¹¹B) = 115 MeV (1980PR09). For reaction (a) see (1971KN05). See also (1979HU1B; theor.).

39. (a) ¹⁸O(¹²C, ¹²C)¹⁸O
(b) ¹⁸O(¹³C, ¹³C)¹⁸O

Elastic angular distributions have been studied at E(¹⁸O) = 32.3 and 35 MeV (1978CH03) and 47.5, 55 and 57.5 MeV (1976WE05) for reaction (a) and at E(¹⁸O) = 31 MeV for reaction (b) (1978CH03). Yields and fusion cross sections are reported by (1976SP07, 1978CH03, 1978CO07, 1978FR05, 1979CH07, 1979KO20, 1980WI09). See also (1979DAZK, 1979EN1F, 1979GAZV, 1981HEZW), (1978LE1T, 1978TS04) and (1978BI1G, 1978VA1A, 1979KR07, 1979NA03, 1980CH1J, 1980LE11, 1980LO02, 1980VA03, 1981HA18; theor.).

40. ¹⁸O(¹⁶O, ¹⁶O)¹⁸O

Angular distributions have been measured at many energies for E(¹⁶O) = 24 to 54.5 MeV and E(¹⁸O) = 25 to 52 MeV, involving besides ¹⁸O_g.s., ¹⁸O*(1.98, 3.55 + 3.63, 3.92, 4.46, 5.10, 7.12) at some energies [see (1978AJ03)], and at E(¹⁸O) = 35 MeV (1981CA1E; to ¹⁸O*(0, 1.98, 4.46, 5.10)). At E(¹⁸O) = 126 MeV ¹⁸O*(9.0) is relatively strongly populated (1979RA10). For yield measurements see (1978FR05). See also (1974FI1D, 1978HO1C) and (1978LE16, 1981CA09, 1981LA16; theor.).

41. (a) ¹⁸O(¹⁷O, ¹⁷O)¹⁸O
(b) ¹⁸O(¹⁸O, ¹⁸O)¹⁸O

Angular distributions involving ¹⁸O*(0, 1.98) are reported at E(¹⁷O) = 36 MeV (1977KA1Y). Angular distributions [reaction (b)] have been studied at E(¹⁸O) = 42 and 52 MeV [see (1978AJ03)] and at E(¹⁸O) = 20 to 36 MeV (1977KA21; to ¹⁸O*(0, 1.98), the latter from 24 MeV). ¹⁸O*(3.55 + 3.63, 4.46, 5.10, 7.12) are also populated: see (1978AJ03). For yield measurements [reaction (b)] see (1977KA21). See also (1979GAZV) and (1978CH10, 1978VO06, 1978VO13, 1981CA09, 1982LA04; theor.).

42. ¹⁸O(¹⁹F, ¹⁹F)¹⁸O

The elastic scattering has been studied at E(¹⁹F) = 27, 30 and 33 MeV (1973GA14). See also (1979GAZV).

43. ¹⁸O(²⁴Mg, ²⁴Mg)¹⁸O

Angular distributions are reported at E(¹⁸O) = 29 and 35 MeV to ¹⁸O*(0, 1.98) (1978CA07). For fusion measurements see (1978TA05, 1981RAZN). See also (1980RA1F).

44. ¹⁸O(²⁷Al, ²⁷Al)¹⁸O

For fusion measurements see (1977EI01, 1979RA21). See also (1980MI1B, 1980SA1L, 1981TA16, 1981WUZZ), (1977SC1G) and (1978VA1A; theor.).

45. (a) ¹⁸O(²⁸Si, ²⁸Si)¹⁸O
(b) ¹⁸O(⁴⁰Ca, ⁴⁰Ca)¹⁸O

Elastic angular distributions are reported at E(¹⁸O) = 36 MeV (1973GA09, 1977EC04), 40 MeV (1978CA07) and 56 MeV (1979ME04, 1979ME12). For fusion measurements see (1979RA21, 1981WUZZ). See also (1979SA27; theor.). For reaction (b) see (1982DA07, 1982LA02; theor.).

46. ¹⁸F(β⁺)¹⁸O Q_m = 1.6555

See ¹⁸F.

47. (a) ¹⁹F(γ, p)¹⁸O Q_m = -7.9934
(b) ¹⁹F(e, ep)¹⁸O Q_m = -7.9934

In reaction (a) ¹⁸O*(1.98, 3.63) are involved: see (1978AJ03), (1979KE1B, 1979TH05) and ¹⁹F. Proton spectra [reaction (b)] have been measured for E_e = 15 to 26 MeV (1975TS03): see ¹⁹F.

48. ¹⁹F(n, d)¹⁸O Q_m = -5.7688

Angular distributions have been measured at E_n = 14 to 14.4 MeV: see (1972AJ02). Gamma rays from the de-excitation of ¹⁸O*(1.98, 3.55, 3.63) are reported by (1976PR08). See also (1978CO18, 1980CO1U) and ²⁰F.

49. ¹⁹F(p, 2p)¹⁸O Q_m = -7.9934

The reaction to the ground state has been studied at E_p = 42.7 MeV (1972HI10).

50. ¹⁹F(d, ³He)¹⁸O Q_m = -2.4998

Many states of ¹⁸O (E_x < 14.6 MeV) have been populated in this reaction: see Table 18.8 (in PDF or PS) in (1978AJ03). Analyzing powers for the ground-state transitions are reported at E_d-bar = 12.4 MeV (1981EN1A). See also (1978RO01).

51. ¹⁹F(t, α)¹⁸O Q_m = 11.8207

Table 18.10 (in PDF or PS) displays the very accurate E_x measurements of (1973OL02) obtained from γ-measurements. This study, as well as the angular correlation work of (1973BE48), leads to some J-assignments, and to the branching ratios displayed in Table 18.3 (in PDF or PS). (1975SO05) have determined Γ_π/Γ for the 0⁺ → 0⁺ transitions from ¹⁸O*(3.63, 5.34) to be (3.0 ± 0.6) × 10^-3 and ≤ 2.3 × 10^-3. Using the adopted values of τ_m for these states [see Table 18.4 (in PDF or PS) in (1978AJ03)] < M >_π = 6.0 ± 0.7 fm² and ≤ 4.5 fm². ¹⁸O*(5.34) appears to be the expected nearly spherical (s_1/2)² state (1975SO05).

52. ¹⁹F(α, αp)¹⁸O Q_m = -7.9934

This reaction, leading to ¹⁸O_g.s., has been studied at E_α = 140 MeV: DWIA provides a fairly good fit to the data (1979NA06).

53. ²¹Ne(n, α)¹⁸O Q_m = 0.696

See (1978AJ03).

54. ²²Ne(d, ⁶Li)¹⁸O Q_m = -8.195

At E_d = 55 MeV ¹⁸O*(1.98, 3.55, 5.10, 6.40) are preferentially populated (1981JAZV). See also (1978BE1H).

55. ²²Ne(³He, ⁷Be)¹⁸O Q_m = -8.082

See (1978AJ03).

56. ²⁶Mg(α, ¹²C)¹⁸O Q_m = -13.004

This reaction has been studied at E_α = 90.3 MeV (1980BE15).