A=20Ne (1978AJ03)

The total reaction cross section has been measured for E(¹⁰B) = 3.7 to 7.3 MeV (1976HI05), and the elastic excitation function has been studied for 8 to 30 MeV (1975DI08). Excitation functions for reactions (a) and (b) have been measured for E_c.m. = 3 to 10 MeV: large resonant structures are observed in most channels of reaction (b) (1978MA07): see (1978EN06). See also ¹⁰B in (1979AJ01).

2. ¹⁰B(¹⁴N, α)²⁰Ne Q_m = 19.5332

At E(¹⁴N) = 25 and 35 MeV angular distributions of the α-particles to ²⁰Ne*(0, 1.63, 4.25, 4.97, 5.62, 5.78, 7.00, 7.17, 7.42, 7.83, 8.45, 8.78, 9.03 + 9.12, 9.99, 10.26, 10.61) have been measured by (1974MA38, 1975LE23). The average behavior of the cross section is generally well described by a statistical mechanism but the reaction mechanism is not purely statistical (1975LE23). For excitation functions see (1972VO02, 1975LE23, 1977MA2V, 1977MA2W): see also (1978EN06). See also (1973ST1A) and (1975KL05; theor.).

3. ¹⁰B(¹⁶O, ⁶Li)²⁰Ne Q_m = 0.270

At E(¹⁶O) = 19.5, 24.3, 31.5, 35.9 and 42 MeV angular distributions have been measured for the ⁶Li ions corresponding to transitions to ²⁰Ne*(0, 1.63, 4.25, 4.97, 5.62 + 5.78, 6.7 - 7.2). Hauser-Feshbach calculations are generally in good agreement with the data (1976LO03). Differential cross sections at 7° have been measured at E(¹⁶O) = 45.6 MeV for many states of ²⁰Ne with E_x < 10.62 MeV (1974FO15). For fusion cross sections see (1977MO1X). See also (1974ST1L, 1978EN06).

4. ¹¹B(¹⁶O, ⁷Li)²⁰Ne Q_m = -3.934

This reaction has been studied at E(¹⁶O) = 60 MeV (1972SC17) and at E(¹¹B) = 114 MeV (1973ST24): a number of states of ²⁰Ne are populated but they are not excited strongly at either energy. See also (1973SC1J).

5. ¹²C(⁹Be, n)²⁰Ne Q_m = 10.3196

At E(⁹Be) = 16, 20 and 24 MeV, angular distributions have been measured for ²⁰Ne*(7.4, 9.3, 11.0, 12.2) (1977EL1E).

6. (a) ¹²C(¹⁰B, d)²⁰Ne Q_m = 5.9589
(b) ¹²C(¹¹B, t)²⁰Ne Q_m = 0.7610

At E(¹²C) = 45 MeV the population of states of ²⁰Ne with E_x = 8.46, 8.78, 9.03, 10.61, 10.67, 10.99, 11.01, 11.66, 11.94, 12.14, 12.39, 12.58, 12.73, 13.05, 13.17, 13.34 [7^-], 13.69, 13.91, 14.29, 14.36, 14.81, 15.17 [6⁺], 15.38 [7^-], 15.71 [(7, 8)], 15.89 [(7)], 16.16, 16.22, 16.51 [(8)], 16.73, 17.39 [9^-], 18.18 and 18.32 MeV is reported. [Values in brackets are J^π suggested on basis of Hauser-Feshbach calculations. The states in italics are well resolved: the authors indicate ± 20 keV for such states.] The relative intensities of the groups to ²⁰Ne*(17.39, 15.38) [J^π = 9^-, 7^-] argue against the existence of a superband (1974KL05, 1976KL03). See also (1973MI1E, 1974ME1C, 1977HI01), (1973BR1C, 1973FO1A, 1973FO1E, 1974FO1J, 1977KL1G), (1975KL05, 1975KL08; theor.) and ²²Na in (1978EN06). For reaction (b) see (1977HI01).

7. ¹²C(¹²C, α)²⁰Ne Q_m = 4.6181

Particle group and γ-ray energy measurements have been made for many states of ²⁰Ne: see Table 20.21 (in PDF or PS). Angular correlation and γ-ray branching measurements [see Table 20.19 (in PDF or PS)] lead to the J^π assignments shown in Table 20.21 (in PDF or PS), which also show level assignments to rotational bands. Angular distributions have been reported at E(¹²C) = 5.6 to 28.3 MeV [see (1972AJ02)] and at E(¹²C) = 4.9 to 9.8 MeV (1973MA09: α₁ → α₃, α₄₊₅, α₆, α₇), 8.5 to 12.5 MeV (1977GA04, 1977GA05: α₀, α₃), 13 to 22 MeV (1976ER03, 1977ER1F: α₀ → α₃, α₆), 13 to 24 MeV (1977VO05: α₀ → α₁₁), 15 MeV (1976BA53: α to ²⁰Ne states with E_x < 8 MeV), 36.6, 36.8 and 37.4 MeV (1976FO15: α₀), 37 MeV (1976EB01: α₀), 37 MeV (1975ME04: see Table 20.21 (in PDF or PS)), 37, 41, 45, 48 and 51 MeV (1975GR21: α to ²⁰Ne*(7.42, 7.83, 9.04)), 38 MeV (1976FO09: α₀, α₆), 45 MeV (1975GR21: α to many states of ²⁰Ne with E_x < 13.4 MeV) and 50 MeV (1977PA19: α-particles to ²⁰Ne*(0, 1.63, 4.25, 5.62, 5.78, 7.42, 7.83, 8.45). Both compound nucleus and direct reaction mechanisms appear to contribute to this reaction in the range E(¹²C) = 36 to 51 MeV. Strong fluctuations in the yield require the presence of narrow compound nuclear levels while the selective population of particular states indicates the presence of a strong direct component. Hauser-Feshbach theory predicts lower cross sections for low-J states than are experimentally observed (1975GR21).

For lifetime measurements see Table 20.20 (in PDF or PS). (1975HO15) have determined |g| = 0.54 ± 0.04 for ²⁰Ne*(1.63).

Studies of yields of particular α-groups are also reported for E(¹²C) = 8 to 16 MeV (1977GA04, 1977GA05: α₀, α₃), 11 to 13 MeV (1973VO01, 1974VO09: α to ²⁰Ne*(6.72, 7.2)), 11.6 to 16 MeV (1977ER1F: α₁, α₆), 13 to 24 MeV (1977VO05: α₀ → α₆, α₁₁) and 25 to 27.1 MeV (1972CO30: α₀ → α₃, α₁₁); only the yields of α₁, α₂, α₆ and α₁₁ show strong fluctuations above E(¹²C) = 20 MeV.

The yields of α-particle groups corresponding to ²⁰Ne states with E_x < 17.5 MeV have been studied in the range E(¹²C) = 32 to 51 MeV by (1974FO20, 1974GR27, 1974SH16, 1975GR21, 1977FO01, 1977PA19). Many strong structures are observed which are interpreted in terms of states in the compound nucleus, ²⁴Mg: see (1978EN06). See also (1976BA22, 1976BA53, 1976EB01, 1976ER03, 1976FO15, 1976FO09, 1977ERZZ, 1977HI04, 1977KE02, 1977MA1M, 1977VAZZ).

See also (1972FI1B, 1973CO1K, 1973FE03, 1974KL1B, 1976NA11, 1977ERZZ), (1973BR1C, 1973FO1E, 1973FO1A, 1973GO1M, 1973SC1B, 1973ST1A, 1974FO25, 1974FO1J), (1973AR1F, 1973MA09, 1973TR1B, 1975FO19, 1977DA07; astrophys. considerations) and (1973SC1K, 1976DA1P, 1977DE2A, 1977MA2X; theor.).

8. ¹²C(¹⁴N, ⁶Li)²⁰Ne Q_m = -4.181

Angular distributions of the ⁶Li ions to ²⁰Ne*(0, 1.63, 4.25, 4.97, 5.62 + 5.78, 6.7 - 7.2) have been measured at E(¹⁴N) = 30 and 36 MeV (1976LO03), 52 and 60 MeV (1971MA23), 52 and 78 MeV (1974HA11: additionally ²⁰Ne*(8.45 - 9.03)), and at E(¹⁴N) = 76.1 MeV and E(¹²C) = 67.2 MeV (1973BE11: not ²⁰Ne*(4.97) but additionally ²⁰Ne*(8.45 - 9.03, 10.26 - 11.02, 11.95 + 12.13, 13.33, 13.92, 16.67, 17.38)). The angular distributions are symmetric about 90° and compound nucleus formation appears to be dominant (1973BE11, 1974HA11). In the work of (1973BE11) states which are particularly strongly populated are ²⁰Ne*(16.67, 17.38, 18.11, 19.16, 19.6). The excitation functions for many states of ²⁰Ne with E_x < 10 MeV have been measured by (1975VO02) for E(¹⁴N) = 20 to 60 MeV and by (1977MO1X) for E(¹⁴N) = 30 to 90 MeV. In addition, see (1976ST07) and ²⁶Al in (1978EN06). See also (1975ZE1C), (1971BA2V, 1973BR1C, 1973FO1E, 1973SC1J, 1973SC1B, 1974ST1L) and (1974KL13, 1975KL05, 1975KL08, 1976KL03; theor.).

9. ¹²C(¹⁸O, ¹⁰Be)²⁰Ne Q_m = -6.3476

At E(¹⁸O) = 80 MeV, the population of ²⁰Ne*(0, 1.63, 4.25, 4.97, 8.78, 11.95) is observed (1974BA15).

10. ¹²C(¹⁹F, ¹¹B)²⁰Ne Q_m = -3.1122

At E(¹⁹F) = 40, 68 and 68.8 MeV angular distributions involving ¹¹B_g.s. and ²⁰Ne*(0, 1.63) are reported (1972SC03). See also (1975PU02) and ³¹P in (1978EN06) and (1972BO21; theor.).

11. ¹³C(¹²C, nα)²⁰Ne Q_m = -0.3283

See (1973SA1G, 1976DA13) and ²⁵Mg in (1978EN06).

12. ¹⁴C(¹⁸O, ¹²Be)²⁰Ne Q_m = -15.75

See (1974BA15, 1974CE1A).

13. (a) ¹⁴N(⁶Li, p)¹⁹F Q_m = 11.1491 E_b = 23.994
(b) ¹⁴N(⁶Li, d)¹⁸F Q_m = 2.942
(c) ¹⁴N(⁶Li, α)¹⁶O Q_m = 19.2628
(d) ¹⁴N(⁶Li, αn)¹⁵O Q_m = 3.5990

Yield curves have been measured for E(⁶Li) = 4.1 to 6.3 MeV for the protons to ¹⁹F*(2.78) and for the d₀ and α₀ groups (1968RI13) and at 5 to 9.2 MeV for the p₀, p₁, d₀, d₁₊₂, α₀, α₁₊₂ and α₃₊₄ groups (1977LE1N): no structure is apparent.

14. ¹⁶O(α, γ)²⁰Ne Q_m = 4.7309

Observed resonances in the yield of capture γ-rays over the range E_α = 0.8 to 10 MeV are displayed in Table 20.22 (in PDF or PS). Information on the character of the radiative decay is shown in Table 20.19 (in PDF or PS). For τ_m, see Table 20.20 (in PDF or PS).

No resonances have been observed below E_α = 1 MeV: see (1971TO06, 1971TO1C) for the data and for the astrophysical implications of this reaction. See also (1971BA1A, 1973CL1E).

The J^π = 5^- state at E_x = 8.45 MeV [E_α = 4.65 MeV] decays by an E2 transition [|M|² = 26 ± 6 W.u.] to the 3^- state at E_x = 5.62 MeV (1971RO33). The J^π = 6⁺ state at E_x = 8.78 MeV [E_α = 5.06 MeV] decays by an E2 transition [|M|² = 20.4 ± 2.4 W.u.] to the 4⁺ state at E_x = 4.25 MeV (1971DI08, 1971RO13). See also (1971RO1C). The J^π = 8⁺ state at E_x = 11.95 MeV decays by an E2 transition to the E_x = 8.78 MeV [J^π = 6⁺] state which then decays via the 4⁺ and 2⁺ members of the ground-state rotational band. The transition probability of the 8⁺ → 6⁺ transition is 7.5 ± 2.5 W.u. which establishes ²⁰Ne*(11.95) as the 8⁺ member of the ground-state band. The experimental E2 transition probabilities in the ground-state band deviate strongly from those predicted by the pure rotational model but agree reasonably well with simple shell-model predictions (1972AL05). The T = 0 isospin impurity of ²⁰Ne*(10.27) [2⁺; 1] is quite large: see (1977FI08) for a discussion of this point and for CVC predictions of the weak magnetism form factors from the radiative widths for the transitions to ²⁰Ne*(1.63, 7.42) [see Table 20.19 (in PDF or PS)]. See also (1977WA1V), (1973AL1C, 1974HA1C) and (1973GA23; theor.).

15. (a) ¹⁶O(α, α)¹⁶O E_b = 4.7309
(b) ¹⁶O(α, 2α)¹²C Q_m = -7.1620

Excitation functions have been measured over a wide energy range for elastically and inelastically scattered α-particles, and γ-rays from the decay of ¹⁶O*(6.13, 6.92, 7.12): see Table 20.20 (in PDF or PS) in (1972AJ02) for the earlier work and (1973HA63: 4.6 MeV and 14.1 to 17.1 MeV; α₀, α₁₊₂; the latter in the higher energy range), (1978ST08: 6.9 to 10.2 MeV; α₀, α₂γ), (1977MA07: 9.2 to 9.7 MeV; γ_6.13), (1975CE01: 12.8 to 14.8 MeV; α₀), (1975BI1H: 14.0 to 18.1 MeV; α₀, α₁₊₂, α₃, α₄) and (1972BU1H: 22.75 to 28.40 MeV). See also (1974BE41) and ¹⁶O in (1977AJ02).

A number of anomalies are observed: they are displayed in Table 20.23 (in PDF or PS). Identifying various of the observed states as members of different rotational bands is discussed by (1972HA07, 1973HA63). The reduced α-widths in the first K^π = 0⁺, 2^- and 0^- bands are small, indicating that the bands could be described in terms of the spherical shell model. The reduced widths within bands are found to decrease sharply with increasing spin (1972HA07, 1973HA63).

For reaction (b) see (1972AJ02). For spallation reactions involving the emission of ⁶Li, ⁷Li, ⁷Be, ⁸Be and ⁹Be ions see (1972RU03, 1974JE1A, 1974RA11). See also (1973AL1C) and (1972HO1E, 1972HO56, 1972SU10, 1973AR1C, 1973EB1A, 1973HO1L, 1973IC01, 1974CA31, 1974FR06, 1974KA1P, 1974KU15, 1974TA17, 1974WA1D, 1975BA05, 1975CU1B, 1975KO28, 1975MA26, 1975NE04, 1975TA1A, 1976CU07, 1976HE19, 1976JA1F, 1976LE20, 1976PA1J, 1977AB03, 1977AN1B, 1977BA12, 1977FL13, 1977IK1C, 1977OH01; theor.).

16. ¹⁶O(α, n)¹⁹Ne Q_m = -12.1344 E_b = 4.7309

The excitation function (activation measurements) has been measured from threshold to E_α = 26.8 MeV (1973GR29). See also (1974LO1B, 1977LI19) and ¹⁹Ne.

17. ¹⁶O(α, p)¹⁹F Q_m = -8.1137 E_b = 4.7309

See ¹⁹F.

18. ¹⁶O(α, ³He)¹⁷O Q_m = -16.434 E_b = 4.7309

See ¹⁷O in (1977AJ02) and (1972RI03; theor.).

19. ¹⁶O(⁶Li, d)²⁰Ne Q_m = 3.257

Deuteron groups have been observed to many states of ²⁰Ne: see Table 20.24 (in PDF or PS). Angular distributions have been measured at a number of energies for E(⁶Li) = 5.5 to 25.8 MeV [see (1972AJ02)] and at 32 MeV (1973GO1K, 1973GO1L; abstracts; to most states shown in Table 20.24 (in PDF or PS) with E_x < 12.2 MeV), (1977GU01: d to ²⁰Ne*(0, 1.63, 4.25, 4.97, 5.62, 7.00)) and at 35.3 to 45 MeV (1975AR20, 1975AR25, 1976AR04: see Table 20.24 (in PDF or PS)). (1977GU01) report that the forward peaks of the deuterons to ²⁰Ne*(4.97, 5.62) [J^π = 2^- and 4^-] cannot be explained solely in terms of zero-range coupled-channel Born approximation α-transfer. The α-particle spectroscopic strengths for the ground state K^π = 0⁺ states have been studied by (1973FO06, 1975AN13). (1973FO06) find 0.22 and 0.15 for the α reduced widths for ²⁰Ne*(8.78, 11.95) in agreement with their assignments as the 6⁺ and 8⁺ members of the K^π = 0⁺₁ band. See also (1972PA16, 1977BE2R). (dγ) coincidences are being studied by (1977SU1M; abstract).

For excitation functions see (1976HOZJ) and ²²Na in (1978EN06). See also (1972BA1P, 1973ST1E), (1971BA2V, 1972GA1E, 1973FO1E, 1973FO1A, 1973OG1A, 1975GO15, 1976OG1A) and (1973YA1A, 1974DO03, 1974NE18, 1976KOZQ; theor.).

20. ¹⁶O(⁷Li, t)²⁰Ne Q_m = 2.264

A number of ²⁰Ne states have been studied in this reaction: see Table 20.24 (in PDF or PS) (1976CO23) and P.D. Parker, private communication. Angular distributions have been reported at E(⁷Li) = 15 to 30.3 MeV [see (1972AJ02)] and at 38 MeV (1976CO23). Correlations between the tritons and the α-particles to ¹⁶O have been studied for a number of states of ²⁰Ne at E(⁷Li) = 20 and 24 MeV: it is suggested that the reaction mechanism is mainly direct (1974PA16). See also (1977DA1J). See also (1972BA1P, 1972CA1D, 1972PA16, 1973ST1E, 1977SA1X), (1971BA2V, 1972GA1E, 1973BR1C, 1973FO1A, 1973OG1A, 1975GO15) and (1972KU12, 1972KU13, 1973AR1C, 1973IC01, 1973MC17, 1974DO03, 1974NE18, 1975BI1J; theor.).

21. ¹⁶O(⁹Be, αn)²⁰Ne Q_m = 3.1576

See (1974VA31).

22. (a) ¹⁶O(¹²C, 2α)²⁰Ne Q_m = -2.5439
(b) ¹⁶O(¹²C, ⁸Be)²⁰Ne Q_m = -2.6358

In reaction (a) at E(¹⁶O) = 58.3 MeV, ²⁰Ne*(0, 1.63, 4.25 + 4.97) are strongly populated (1974WI05). See also ²⁴Mg in (1978EN06). For fusion studies see (1976KO24, 1976SW02, 1976WE15, 1977CH10) and for other yield measurements see (1976EY01, 1977SW01) and ²⁸Si in (1978EN06). See also (1975SC2A).

Angular distributions in reaction (b) have been studied at E(¹⁶O) = 27.1 to 37.1 MeV (1977HU1C; g.s.), 30.2, 30.7, 31.2 and 32.1 MeV (1976VI05, 1977BR24; g.s.) and 46.4 MeV (1976JA19; g.s.), at E(¹²C) = 56 MeV (1976MA12: to ²⁰Ne*(0, 1.63, 4.25, 5.8, 7.2, 8.8, 10.34, ≈ 12)) and at 78 MeV (1977SA1X, 1977SA2A, 1977SA2F, 1977SA2G). At E(¹²C) = 56 MeV the strongest groups are those to the 6⁺ and 5^- states ²⁰Ne*(8.78, 10.26) (1976MA12). See also (1972WO10). At E(¹²C) = 78 MeV, ⁸Be - α correlations have led to a number of J^π determinations and to measurements of Γ_α₀/Γ: see Table 20.24 (in PDF or PS) (P.D. Parker, private communication). For yield measurements see (1976JA19, 1976VI05, 1977BR24, 1977FL1F, 1977HU1C) and ²⁸Si in (1978EN06). See also (1972PA1G, 1974ME09) and (1973YO03, 1974KR1E, 1975BA2J, 1976BU22; theor.).

23. ¹⁶O(¹³C, ⁹Be)²⁰Ne Q_m = -5.9170

At E(¹³C) = 105 MeV the cross sections for formation of the K^π = 0⁺ states ²⁰Ne*(0, 1.63, 4.25, 8.78, 11.95) are in excellent agreement with shell-model predictions. ²⁰Ne*(10.26, 17.38, 21.1), as well as the 4⁺, 6⁺ and 8⁺ states above, are strongly populated (1976PI06).

24. ¹⁶O(¹⁴N, ¹⁰B)²⁰Ne Q_m = -6.8823

At E(¹⁴N) = 155 MeV states with high angular momentum appear to be preferentially excited (1976NA22).

25. ¹⁶O(¹⁶O, ¹²C)²⁰Ne Q_m = -2.4310

Angular distributions have been reported at E(¹⁶O) = 23.9 MeV (1974SP06; g.s.), 44.3 - 54.5 MeV (1972SI17, 1973SI1D; to ²⁰Ne*(0, 1.63, 4.25)), 51.5 MeV (1974RO04; to ²⁰Ne*(0, 1.63, 4.3, 5.6 - 6.1, 8.5 - 8.9)) and 95.2 MeV (1977MO1H; to ²⁰Ne*(0, 1.63)). At 55.5 MeV (1973ER1B, 1974ER1A; prelim.), ²⁰Ne*(0, 1.63, 4.25, 4.97, 7.00) are populated. For yield measurements see (1972SI17, 1973PE1D, 1974ER1A, 1974RO04, 1974SP06, 1977KO16) and ³²S in (1978EN06). In particular the fusion cross section shows evidence of periodic structure between E_c.m. = 14 and 28 MeV, as predicted by the optical model (1977KO16): a resonance (Γ ≤ 1 MeV) at E_c.m. = 26.5 MeV is suggested to be an α-exchange resonance. Polarization measurements are reported by (1977PO1E). See also (1973ST1A, 1973ST1F) and (1972AR11, 1973AR18; theor.).

26. ¹⁶O(¹⁸O, ¹⁴C)²⁰Ne Q_m = -1.4970

Angular distributions are reported at E(¹⁸O) = 28 and 32 MeV (1971BA68).

27. ¹⁶O(¹⁹F, ¹⁵N)²⁰Ne Q_m = 0.7171

At E(¹⁹F) = 36 MeV (1973GA14) and E(¹⁶O) = 46, 58 and 68 MeV (1975PO01) angular distributions involving ²⁰Ne*(0, 1.63) are reported. (1975PO01) have also studied ²⁰Ne*(4.25): the strong population of the 4⁺ state may indicate evidence for a two-step process. See also (1976LO06; theor.).

28. (a) ¹⁷O(³He, n)¹⁹Ne Q_m = 4.299 E_b = 21.164
(b) ¹⁷O(³He, α)¹⁶O Q_m = 16.4335

For reaction (a) see ¹⁹Ne. The ground state excitation energy for reaction (b) has been measured for E(³He) = 7.0 to 10.0 MeV: it shows a resonance corresponding to ²⁰Ne*(28.). This resonance is also observed in the ¹⁶O(α, α) elastic scattering. It is interpreted in terms of a quasi-molecular α-particle cluster model (1969CO19).

29. ¹⁷O(α, n)²⁰Ne Q_m = 0.587

Angular distributions have been measured at E_α = 9.8 to 12.3 MeV by (1967HA14: n₁, n₂, n₄₊₅). The neutron decay of the lowest T = 3/2 state in ²¹Ne to ²⁰Ne*(1.63) has been studied by (1976MC12). The total neutron yield has been measured for E_α = 1.0 to 5.3 MeV by (1973BA10). The astrophysical import of this reaction is discussed by (1973CL1E, 1975FO19). See also ²¹Ne in (1978EN06).

30. ¹⁷O(⁶Li, t)²⁰Ne Q_m = 5.370

See (1973ST1E, 1977MA2G). See also (1974KU07; theor.).

31. ¹⁸O(³He, n)²⁰Ne Q_m = 13.1199

Neutron groups have been observed to a number of ²⁰Ne states: see Table 20.25 (in PDF or PS) (1969AD02, 1970GU08, 1977EV01). Angular distributions have been measured at E(³He) = 2.8 to 7.3 MeV (see (1972AJ02)) and at 18 (1977EV01) and 18.3 MeV (1975PE11).

32. ¹⁸O(¹¹B, ⁹Li)²⁰Ne Q_m = -10.027

At E(¹¹B) = 114 MeV, ²⁰Ne*(4.25, 8.9, 10.39, 15.43) [± 60 keV] are relatively strongly populated. ²⁰Ne*(0, 1.63, 5.78, 7.17) are also excited (1973ST24). See also (1973SC1J).

33. ¹⁸O(¹²C, ¹⁰Be)²⁰Ne Q_m = -4.7816

At E(¹²C) = 46 MeV angular distributions to ²⁰Ne*(0, 1.63, 4.25) have been studied: the 2p spectroscopic factors are 0.58, 0.24 and 0.20, respectively (1975CO15).

34. ¹⁹F(p, γ)²⁰Ne Q_m = 12.8447

Over the range E_p = 2.9 to 12.8 MeV, the γ₀ and γ₁ yields are dominated by the E1 giant resonance (Γ ≈ 6 MeV) with the γ₁ giant resonance displayed upward in energy. Strong, well correlated structure is observed with a characteristic Γ ≈ 175 keV. Angular distributions taken over the energy range do not vary greatly with energy. They are incompatible with γ₀ and γ₁ coming from the same levels in ²⁰Ne (1967SE02). See also (1973AV1B).

The yield curve for 11.2 MeV γ-rays [from the decay of ²⁰Ne*(11.23), J^π = 1⁺; T = 1, to the ground state] displays a resonance at E_p = 4.090 ± 0.005 MeV [²⁰Ne*(16.73)]. The 11.2 MeV γ-rays are isotropic which is consistent with the presumed 0⁺ character of this lowest T = 2 state in ²⁰Ne: Γ_pΓ_γ/Γ ≈ 0.5 eV. Since Γ_p/Γ (from the elastic scattering) is ≈ 0.1, Γ_γ ≈ 5 eV (1967KU06). For E_p = 5.65 to 6.21 MeV, the γ₀ and γ₁ yields are not resonant but the yield of 10.6 MeV γ-rays is resonant at 5.879 ± 0.007 MeV [Γ_c.m. = 9.5 ± 3 keV, Γ_p₀Γ_γ/Γ ≈ 0.05 eV; Γ_γ ≈ 0.3 eV]. The 10.6 MeV γ-ray is due to the cascade decay of ²⁰Ne*(18.43), J^π = 2⁺; T = 2 via ²⁰Ne*(12.22) to the 2⁺ state at 1.63 MeV (1972KU24). (1976MA01) have determined the upper limits to the strengths of the transitions to various states of ²⁰Ne from the 0⁺ and 2⁺ T = 2 states: these are displayed in Table 20.19 (in PDF or PS). No evidence is found for an isotensor transition amplitude (1976MA01).

Resonances observed in this capture reaction are displayed in Table 20.26 (in PDF or PS). See also (1973GL1B, 1973GL1C, 1973HA1X, 1974AD1B, 1974HA1G, 1974HA1N) and (1977SC02, 1977SC08; theor.).

35. (a) ¹⁹F(p, p)¹⁹F E_b = 12.8447
(b) ¹⁹F(p, p')¹⁹F*

The elastic scattering has been studied in the range E_p = 500 to 2000 keV by (1954DE1A, 1954PE1A, 1955BA1C, 1955WE44, 1956DE33, 1963BE19). Parameters for the observed resonances are exhibited in Tables 20.27 (in PDF or PS) and 20.28 (in PDF or PS) taken mainly form (1955BA1C). Some unresolved structure is observed at E_p = 900, 1092 and 1137 keV, in addition to a broad structure near E_p = 1700 keV (1955WE44). A sharp anomaly is observed in the elastic scattering at E_p = 4.096 ± 0.003 MeV (1967BL19), 4.090 ± 0.005 MeV (1967KU06). It is an s-wave resonance corresponding to the 0⁺; T = 2 state at E_x=16.73 MeV (1967BL19, 1967KU06). There is no indication of this resonance in the p₃, p₄ or p₅ yields (1967KU06). The amplitude of the T = 1 or T = 0 impurity in this state is ≈ 1.5% (1967BL19). In the range E_p = 5.65 to 6.21 MeV, a single anomaly is seen in the elastic scattering at E_p = 5.879 ± 0.007 MeV. The interference patterns show that the scattering is d-wave, corresponding to the excitation of the 2⁺; T = 2 state at E_x = 18.43 MeV (1972KU24). The 5.88 MeV anomaly also appears in the p₁, p₃, p₄ and p₅ yields (1972KU24). The parameters of these two T = 2 states are shown in Table 20.27 (in PDF or PS). The elastic scattering has also been studied for E_p = 4.2 to 7.5 MeV by (1967TH06). The total reaction cross section is reported for E_p = 24.9 to 46.3 MeV by (1974MC19: 8 energies in that range).

Resonances for inelastic scattering involving ¹⁹F*(0.11) (J^π = 1/2^-) and ¹⁹F*(0.197) (J^π = 5/2⁺) [p₁ and p₂] are listed in Table 20.29 (in PDF or PS) (1955BA94, 1963BE19). In general the resonances observed are identical with those reported from other ¹⁹F + p reactions, although the relative intensities differ greatly. The p₂ scattering has been measured at E_p = 5.6 to 6.3 MeV (1967TH06), and at E_p = 3.5 to 7.0 MeV the yields of p₂, p₃, p₄ and p₅ show structures (1973BE1H; prelim.). The analyzing power has been measured for the p₀, p₂ and p₅ groups with polarized protons in the range 4 to 10 MeV: strong structures are observed for p₀ (1975EN1C, 1976EN1C; prelim. work; and R. Kaita, private communication). See also (1972AJ02, 1974HA1G) and ¹⁹F.

36. ¹⁹F(p, n)¹⁹Ne Q_m = -4.0207 E_b = 12.8447

Yield measurements have been reported for E_p = 4.23 to 11 MeV: see (1972AJ02) and (1972KU24: 5.78 to 5.96 MeV; σ_t, n₀, n₁₊₂). Observed resonances are displayed in Table 20.30 (in PDF or PS). A narrow anomaly is reported in the n₀ and n₁₊₂ yields at E_p = 5.879 ± 0.007 MeV, corresponding to the 2⁺; T = 2 state of ²⁰Ne at 18.43 MeV (1972KU24). See also ¹⁹Ne.

37. ¹⁹F(p, α)¹⁶O Q_m = 8.1137 E_b = 12.8447

Many resonances occur in this reaction. They are displayed in Tables 20.31 (in PDF or PS), 20.32 (in PDF or PS) and 20.33 (in PDF or PS) depending on whether they are observed in the α₀ yield [Table 20.31 (in PDF or PS)], in the α₁ [or α_π] yield to ¹⁶O*(6.05) [Table 20.32 (in PDF or PS)] or in the α₂, α₃ and α₄ yields [or in the yield of the γ-rays from ¹⁶O*(6.13, 6.92, 7.12)] [Table 20.33 (in PDF or PS)]. Resonances for α₀ and α₁ are required to have even J, even π or odd J, odd π, while the α₂, α₃ and α₄ resonances are all odd-even or even-odd, with the exception of the T = 2 resonance discussed below.

A listing of the earlier yield studies is given in (1972AJ02). A detailed discussion of the evidence leading to many of the J^π assignments shown in Table 20.33 (in PDF or PS) is given in (1959AJ76). Recent measurements are reported by (1974CA22: E_p = 0.6 to 1.8 MeV; α₀ → α₄), (1972HE39: 1.3 to 2.2 MeV; γ_6.13, γ_6.92, γ_7.12) and (1972KU24: 5.65 to 6.20 MeV; α₀ → α₅, α₇ → α₉). The width of the forbidden decay of the 1⁺ state at 13.17 MeV [see Table 20.33 (in PDF or PS)] by α₀, Γ_γ₀ ≲ 7 × 10^-6 eV (1974KRZE; prelim. results). Anomalies are observed in α₀, α₁, α₂, α₄ and α₈ but not in α₃, α₅, α₇ and α₉ corresponding to the formation of the 2⁺; T = 2 state at 18.43 MeV [E_p = 5.88 MeV] (1972KU24). The analyzing power for α₀, α₁₊₂, α₃ and α₄ have been measured for E_p = 4 to 10 MeV: strong structures are observed (1975EN1C, 1976EN1C; prelim. results; and R. Kaita, private communication). See also (1974HA1G, 1974LO1B, 1976CA1P), (1976GA1K; theor.), (1977CL1F; astrophys.) and ¹⁶O in (1977AJ02).

38. ¹⁹F(p, ⁸Be)¹²C Q_m = 0.8599 E_b = 12.8447

The excitation curves show strong resonant behavior (cross sections up to 1.5 mb/sr) for E_x = 15.3 to 18.7 MeV, over which region 28 angular distributions have been measured. Twelve states with J^π ≤ 4⁺ have been observed. The strongly populated states are in better agreement with those reported in the (p, α₁) yield to ¹⁶O*(6.05) [J^π = 0⁺] than those reported in the (p, α₀) yield (1969GO1B, 1971GO1R). It is suggested that most of the observed states are of 8p - 4h and 12p - 8h configurations (1971GO1R). [(1969GO1B, 1971GO1R) are preliminary reports.]

39. (a) ¹⁹F(p, t)¹⁷F Q_m = -11.0999 E_b = 12.8447
(b) ¹⁹F(p, ³He)¹⁷O Q_m = -8.320

For reaction (a) see ¹⁷F in (1977AJ02) and (1974NE03). The polarization analyzing powers for the reaction to ¹⁷O*(0, 0.87) have been measured at E_p = 49.5 MeV (1974NE03).

40. ¹⁹F(d, n)²⁰Ne Q_m = 10.6200

Levels of ²⁰Ne derived from reported neutron groups are displayed in Table 20.34 (in PDF or PS). Angular distributions have been measured at E_d = 0.5 to 6.1 MeV: see (1972AJ02) and at E_d-bar = 8 MeV (1976BEYD: n₁, n₆). The branching ratio for the γ-decay of the lowest 1⁺; T = 1 state [²⁰Ne*(11.23)] to the ground state to ²⁰Ne*(1.63) is 0.53 ± 0.07 (1973KU1E: E_d = 5.5 MeV). See also (1975LE1K; applied) and (1972AJ02).

41. ¹⁹F(³He, d)²⁰Ne Q_m = 7.3511

Levels of ²⁰Ne observed in this reaction are displayed in Table 20.35 (in PDF or PS). Deuteron angular distributions have been measured at E(³He) = 9.5 and 10.0 MeV (1965SI18), 13.0 MeV (1963JA01), 16 MeV (1974VE03, 1976SE10), 18 MeV (1975BE02, 1976FO05) and 21 MeV (1973OB04). Spectroscopic factors obtained by (1973OB04, 1975BE02, 1976FO05, 1976SE10) are shown in Table 20.35 (in PDF or PS). The angular distribution of the deuterons to ²⁰Ne*(4.25) is explained in terms of inelastic effects (1974VE03). See also (1965SI18) and (1977SU04; theor.).

Gamma-ray measurements are summarized in Tables 20.19 (in PDF or PS) (1977MA07), 20.20 (in PDF or PS) (1969AN08) and 20.35 (in PDF or PS) (1969AN08, 1977MA07). See also (1972FO16, 1973FO1A, 1973FO1E, 1974FO1J).

42. ¹⁹F(α, t)²⁰Ne Q_m = -6.9694

At E_α = 28.5 MeV angular distributions are reported for the tritons to ²⁰Ne*(0, 1.63, 4.25, 4.97, 5.62 + 5.78, 7.00 + 7.17 + 7.19) (1967HA23; DWBA). The distributions of the tritons to ²⁰Ne*(0, 1.63, 4.25) [J^π = 0⁺, 2⁺ and 4⁺, respectively] have been reanalyzed in terms of the collective-model coupled-channels Born-approximation theory: C²S for these three states are 0.08, 0.16 and 0.0 (CCBA) [the DWBA results are nearly the same]. Agreement with the values obtained in the (d, n) and (³He, d) reactions is poor (1974OB02). Angular distributions have also been reported at E_α = 18.5 and 28.4 MeV: see (1972AJ02).

43. ¹⁹F(⁷Li, ⁶He)²⁰Ne Q_m = 2.867

Angular distributions have been studied at E(⁷Li) = 34 MeV for the transitions to ²⁰Ne*(0, 1.63, 4.25, 4.97 (partial), 5.62, 5.78, 6.72, 7.1, 7.42). The spectroscopic factors, C²S, for ²⁰Ne*(0, 1.63, 4.25, 5.78, 6.72, 7.42) are 0.36, 0.54, 0.06, 0.20 and 0.22, respectively, in good agreement with those reported in the (d, n) and (³He, d) reactions (1975WI30).

44. ¹⁹F(¹⁰B, ⁹Be)²⁰Ne Q_m = 6.259

See (1973ME1F).

45. ²⁰F(β^-)²⁰Ne Q_m = 7.0259

The decay is principally to ²⁰Ne*(1.63) with a half-life of 11.00 ± 0.02 sec: see reaction 1 in ²⁰F and Table 20.36 (in PDF or PS) for the branching to various ²⁰Ne states. The 0.02% branching to ²⁰Ne*(4.97) [J^π = 2^-] is consistent with the assignment J^π = 2⁺ to the ground state of ²⁰F (1969GA05), as are measurements of the β - γ circularly polarized correlation (1961FR02, 1965MA28). When the β - γ correlation is described by W(θ) = 1 + pcos²θ, p has a value slightly different from zero and it varies linearly with E: dp/dE = +0.09 ± 0.05% MeV^-1 (1977MCZZ). (1977TR1H) report dp/dE = +0.05 ± 0.07% MeV^-1 and (1977RO1Y) find +0.02 ± 0.02 MeV^-1. The β-decay asymmetry, (ft)⁺/(ft)^- = 1.044 ± 0.010 (1975AL27), 1.025 ± 0.013 (1976GE08): see also reaction 58 and (1974ST10). (1977RO1Y) find, by comparison with ²⁰Na, a vanishing second class current: the ratio of the second-class axial matrix element to the main first-class one is 1.1 ± 1.5 and a first-class second-forbidden axial contribution is 40 ± 8.

The energy of the γ-ray from ²⁰Ne*(1.63) is 1634.8 ± 0.6 keV (1967VA08), 1632.6 ± 0.8 keV (1966AL12), 1633.7 ± 0.3 keV (1968SP01), 1633.6 ± 0.3 keV (1972OP01). The γ-ray from the (4.97 → 1.63) transition has E_γ = 3334.3 ± 0.7 keV, ΔE_x = 3334.6 ± 0.7 keV, and using the E_x for ²⁰Ne*(1.63) shown in Table 20.18 (in PDF or PS), E_x for ²⁰Ne*(4.97) = 4968.4 ± 0.8 keV (1969GA05).

46. (a) ²⁰Ne(γ, n)¹⁹Ne Q_m = -16.8653
(b) ²⁰Ne(γ, 2n)¹⁸Ne Q_m = -14.419
(c) ²⁰Ne(γ, p)¹⁹F Q_m = -12.8447
(d) ²⁰Ne(γ, α)¹⁶O Q_m = -4.7309

Bremsstrahlung measurements show peaks in the neutron yield (reaction (a)) at 17.8, 18.8, 19.1, 20.1, (22.0), (23.0) and (24.8) MeV [numbers in parentheses refer to relatively weak and broad structures]. The giant dipole resonance is centered at ≈ 20 MeV and the integral cross section to 28 MeV exhausts half of the dipole sum rule (1975WO06). The cross section for (γ, Tn) using monoenergetic photons shows a structure at 18 MeV and some fluctuations atop the broad giant dipole resonance, σ_max ≈ 7 mb. The double photoneutron cross section, σ(γ, 2n), is dominated by a single peak at ≈ 20.5 MeV, σ_max ≈ 1.1 mb (1974VE06). See also (1972AJ02, 1975BR1F, 1975WO06, 1977DA1B) and (1973ROYN, 1975SC05; theor.). For reaction (c) see (1962DO1A, 1963FI1B, 1969HO16) and (1975SC2B; theor.). For reaction (d) see (1959HA1C) and reaction 47.

47. (a) ²⁰Ne(e, e)²⁰Ne
(b) ²⁰Ne(e, ep)¹⁹F Q_m = -12.8447
(c) ²⁰Ne(e, eα)¹⁶O Q_m = -4.7309

The ²⁰Ne charge radius, r_rms = 3.116 ± 0.025 fm (using a Born approx.) (1971MO15). See also the discussion in (1973SI31).

Form factors for many of the excited states of ²⁰Ne with E_x < 8 MeV have been reported: see (1973SI31; E_e = 77.0, 81.3, 102.4, 110.5, 114.4 MeV) and (1972MI06; 200 and 250 MeV). The monopole matrix elements for the 0⁺ → 0⁺ transitions are 7.4 ± 2.0 and 6.9 ± 1.4 fm² for ²⁰Ne*(6.72, 7.19) (1972MI06) while (1973SI31) calculate Γ_π = 3.9 × 10^-5 eV for ²⁰Ne*(6.72). B(E2)(↑) is 0.028 ± 0.004 e² · b² for the transition to ²⁰Ne*(1.63). The transitions to ²⁰Ne*(4.25, 7.83) correspond to 23 ± 5 W.u. and 0.77 ± 0.25 W.u. (1973SI31). (1972MI06) report B(E2)(↑) = 0.13 ± 0.03 and 0.83 ± 0.13 W.u. for the transitions to ²⁰Ne*(7.42, 7.83).

At E_e = 39 and 56 MeV, the 180° inelastic scattering is dominated by the transition to a J^π = 1⁺; T = 1 state at E_x = 11.22 ± 0.05 MeV with Γ_γ₀ = 11.2^+2.1_-1.8 eV. A subsidiary peak is observed corresponding to a state at an E_x = 0.35 ± 0.03 MeV higher [if J^π = 1⁺ or 2⁺, Γ_γ₀ = 0.65 ± 0.18 or 0.40 ± 0.13 eV]. A number of small peaks are also reported corresponding to E_x ≈ 12.0, 12.9, 13.9, 15.8, 16.9, 18.0 and 19.0 MeV ((1971BE18), and W.L. Bendel, private communication). See also (1975CH41, 1975SZ1B).

A study of reaction (b) at E_e = 30 MeV shows strong resonances (assuming ground-state transitions) at E_x = 17.70, 18.87, 19.87 and 21.02 MeV, respectively, as well as some weaker structures (1962DO1A).

Reaction (c) has been studied in order to obtain the (γ, α₀) cross section in the giant resonance region: the cross section at 90° for E_x = 15 to 24 MeV is dominated by an E1 resonance [1^-; T = 1, with an admixture of T = 0 which permits the α₀ decay] at E_x = 20 MeV; lesser E1 structures are reported at E_x = 16.7, 17.1, 21 and 22 MeV. A relatively strong 2⁺; T = 0 resonance appears at E_x = 18.5 MeV, and evidence is reported for increasing E2 strength below 16 MeV (1975SK06).

48. ²⁰Ne(n, n)²⁰Ne

See ²¹Ne in (1978EN06) and (1976ZA1E; theor.).

49. (a) ²⁰Ne(p, p)²⁰Ne
(b) ²⁰Ne(p, pα)¹⁶O Q_m = -4.7309
(c) ²⁰Ne(p, 2p)¹⁹F Q_m = -12.8447

Angular distributions of elastically scattered protons and of a number of inelastic groups have been measured for E_p = 2.15 to 41.8 MeV: see (1972AJ02) for the earlier work and (1969MA48: 3.66 to 5.90 MeV; p₀, p₁), (1976DE12, 1976SW1C: 24.5 MeV; p to ²⁰Ne*(0, 1.63, 4.25, 4.97, 5.62, 5.78, 6.72, 7.00, 7.17 + 7.19, 7.42, 7.83, 8.45, 8.69, 8.78, 9.03, 9.12, 9.31 + 0.02, 9.51)), (1973DE06, 1974DE46: 30 MeV; p₀, p₁, p₂) and (1977CO1G: 35.2 MeV; p₀). The E_p = 24.5 and 30 MeV angular distributions for the 0⁺, 2⁺ and 4⁺ members of the ground-state K^π = 0⁺ band are well fitted using coupled-channels calculations and deformation parameters of β₂ = +0.47 ± 0.04 and β₄ = +0.28 ± 0.05. When the 6⁺ state is included [²⁰Ne*(8.78)], the fit is improved if β₆ = -0.10 is included (1973DE06, 1974DE46, 1976DE12, 1976SW1C). The state at E_x = 9.31 ± 0.02 MeV is suggested to have J^π = (4⁺) and to be the 4⁺ member of the K^π = 0⁺ band based on ²⁰Ne*(6.72): β₂ = 0.15 (1976SW1C): see, however, Table 20.35 (in PDF or PS).

For p - γ angular correlations see (1972AJ02). See also (1969MA48). For polarization measurements see (1972DE18, 1976DE12, 1977PL1C) and ²¹Na in (1978EN06). For yield measurements see (1972HI1C, 1976SW1C) and ²¹Na in (1978EN06). For reaction (b) see (1971EP03). See also (1970QU1C). For a study of spallation see (1974PA10). See also (1972AS13, 1976AM04, 1976ES1B; theor.). For reaction (c) see (1964KA1A; theor.).

50. ²⁰Ne(d, d)²⁰Ne

Angular distributions have been reported at E_d = 10.95 to 11.8 MeV and at 52 MeV [see (1972AJ02)], at E_d-bar = 10.0 to 12.0 MeV (1975DA1F; d₁), 11.6 MeV (1973BR15; d₀) and 11.66 MeV (1975DA1F; d₂) and at E_d = 40 MeV (1974EP1B; d₁ and d₂). See ²²Na in (1978EN06) for polarization and yield measurements. See also (1971SI24; theor.).

51. ²⁰Ne(t, t)²⁰Ne

The elastic scattering has been studied at E_t = 1.80 and 2.00 MeV (1969HE08). See also (1972SC10; theor.).

52. ²⁰Ne(³He, ³He)²⁰Ne

Angular distributions have been measured at E(³He) = 10 to 35 MeV [see (1972AJ02)] and at 68 MeV (1974DE05: ³He to ²⁰Ne*(0, 1.63, 4.25)). The angular distributions at E(³He) = 68 MeV are well fitted by a coupled channels calculation with β₂ = 0.47 and β₄ = 0.17 (1974DE05). See also (1975MA25, 1976MA36; theor.).

53. (a) ²⁰Ne(α, α)²⁰Ne
(b) ²⁰Ne(α, 2α)¹⁶O Q_m = -4.7309
(c) ²⁰Ne(α, ¹²C)¹²C Q_m = -4.6181

Angular distributions have been measured to low-lying states of ²⁰Ne at E_α = 3.8 to 155 MeV: see (1972AJ02) and (1975AB1H, 1975DA1E: α₀; 3.8 to 8 MeV), (1977EN01: α₀; 20.2 - 23.0 MeV), (1975CO1K: α₀; 26.6, 27.2 and 27.8 MeV), (1972RE05: α₀, α₁, α₂; 104 MeV) and (1976KN05: α₁ and α to ²⁰Ne*(18.1 - 28.2); 155 MeV). A coupled-channel analysis of the work at E_α = 104 MeV leads to β₂ = +0.35 ± 0.01, β₄ = +0.11 ± 0.01, Q₂₀ = +0.46 ± 0.02 b and Q₄₀ = +0.026 ± 0.002 b² (1972RE05). At E_α = 155 MeV (1976KN05) find that the strength concentrated in the giant quadrupole resonance exhausts more than 30% of the isoscalar energy weighted sum rule. See also (1975MO04, 1976YO02). Yield measurements are reported by (1974BA76: E_α = 10.25 to 14.82 MeV; most α-groups to ²⁰Ne* states with E_x < 8 MeV) and by (1975AB1H, 1975CO1K, 1975CO1M, 1975DA1E). See also (1974HA1C, 1976HA1Q) and (1971FE1F, 1972MA65, 1972RE01, 1972SH09, 1973RE11, 1974PI11, 1974MA11, 1975GI10, 1976BE1P, 1976MA19, 1976MA36, 1977KN02; theor.).

For reaction (b) see ¹⁶O in (1977AJ02), (1974EP01: E_α = 78.6 MeV) and (1977WA1M: E_α = 140 MeV). See also (1974MU1D), (1975RO1B) and (1975MI11; theor.). For reaction (c) see (1963LA08). See also ²⁴Mg in (1978EN06).

54. ²⁰Ne(⁷Li, ⁷Li)²⁰Ne

The elastic angular distribution has been measured at E(⁷Li) = 36 MeV (1976CO23).

55. ²⁰Ne(¹²C, ¹²C)²⁰Ne

Elastic angular distributions have been obtained at E(¹²C) = 22.2, 27.2, 32.3, 37.3 and 42.7 MeV [see (1974VA18)] and at E(²⁰Ne) = 65.7 MeV (1975DO06). For a fusion study, see (1977CO1Q). See also (1977PR1F) and (1976VA12, 1977OS02; theor.).

56. ²⁰Ne(¹⁶O, ¹⁶O)²⁰Ne

Angular distributions have been studied at E(²⁰Ne) = 50 MeV (1976ST18) and 94.8 MeV (1977MO1H) involving ¹⁶O_g.s. and ²⁰Ne*(0, 1.63, 4.25): qualitative agreement is found with the assumption of an α-cluster exchange process dominating at backward angles (1976ST18). See also (1975ZI1C).

57. ²⁰Ne(³²S, ³²S)²⁰Ne

The static quadrupole moment of ²⁰Ne*(1.63), Q₂₀ = +0.94 ± 0.38 b (1969SC08).

58. ²⁰Na(β⁺)²⁰Ne Q_m = 13.887

²⁰Na has a half-life of 446 ± 3 msec: see reaction 1 in ²⁰Na. It decays to a number of states of ²⁰Ne, principally ²⁰Ne*(1.63): see Table 20.37 (in PDF or PS). The ratio of the mirror decays ²⁰Na β⁺/→ ²⁰Ne*(1.63) and ²⁰F β^-/→ ²⁰Ne*(1.63), (ft)⁺/(ft)^- = 1.026 ± 0.024 (1973TO08), 1.033 ± 0.022 (1976IN06). (1977RO20) obtain a correlation W₊(θ) = 1+ cos²θ[(-4.0 ± 0.7) × 10^-3E + (1.3 ± 0.9) × 10^-4E²](p/E)²: assuming the validity of CVC this leads to a vanishing second-class current. See also reaction 45. The β - α angular correlation involving the allowed transition to ²⁰Ne*(7.42) is consistent with the predictions of the CVC theory (1977FR08). See also (1972TO08, 1973IN01, 1974AL11, 1975RO1R, 1977RO1W) and (1971WI1C, 1972EM02, 1972WI1C, 1973LA03, 1974WI1L, 1975WI1E, 1977CA11, 1977OK1E, 1977WI02; theor.).

59. ²¹Ne(p, d)²⁰Ne Q_m = -4.537

Angular distributions have been measured for the first four deuteron groups at E_p = 14.1 MeV (1972HE24) and 20 MeV (1970HO19). (1972HE24) report spectroscopic factors of 0.50 and 0.14 for ²⁰Ne*(1.63, 4.97): the other two distributions do not show direct reaction features.

60. ²¹Ne(d, t)²⁰Ne Q_m = -0.504

The T = 1 states observed in this reaction, and the analog states observed in ²⁰F in the (d, ³He) reaction, are displayed in Table 20.16 (in PDF or PS). The spectroscopic factors of analog states are consistent to within 20% for states excited by a single l-transfer. T = 0 states are displayed in Table 20.38 (in PDF or PS) (1974MI13).

61. ²¹Ne(³He, α)²⁰Ne Q_m = 13.816

See (1973FO1E).

62. ²²Ne(p, t)²⁰Ne Q_m = -8.644

Angular distributions have been reported at E_p = 26.9, 35.1 and 42.4 MeV (1971FA07: t₀, t₁, t₂, t₃, t₄₊₅, t₆) and at 43.7 MeV (1964CE05). At the higher energy the distributions of the tritons to the ground state of ²⁰Ne and to the first 0⁺; T = 2 state [E_x = 16.722 ± 0.025 MeV (1969HA38)] have been fitted by L = 0 and the tritons to ²⁰Ne*(18.5) by L = 2. The latter is the first 2⁺; T = 2 state (1974CE1A). The 0⁺; T = 2 state [²⁰Ne*(16.73)] decays by α₀ [-6 ± 5%], α₁ + α₂ [35 ± 12%], α₃ + α₄ [29 ± 12%], p₀ + p₁ + p₂ [14 ± 9%] and p₃ + p₄ + p₅ [13 ± 8%] [measured branching ratios in percent are given in the brackets] to final states in ¹⁶O and ¹⁹F (1970MC04). The ratios of the cross section for formation of the analog states ²⁰Ne*(10.27)/²⁰F*(0) and ²⁰Ne*(12.25 ± 0.03)/²⁰F*(1.85) are 2.00 ± 0.20 and 1.40 ± 0.15, respectively, at E_p = 45 MeV (1969HA19). See also (1971GO1Q).

At E_p = 40 MeV angular distributions of the tritons to ²⁰Ne*(4.97, 5.62, 7.00) [J^π = 2^-, 3^- and 4^-, respectively] have been measured. Coupled-channels calculations reproduce the distributions to the 2^- and 3^- states, but the distribution to the 4^- states cannot be explained entirely in terms of multistep inelastic processes (1975CH17). See also (1974VO11).

See also (1973FO1E) and (1972FE1A, 1972OL04, 1972SC10, 1973BA18, 1973OL03, 1973UD01, 1976KI09; theor.).

63. ²²Ne(α, ⁶He)²⁰Ne Q_m = -16.155

See (1972AJ02).

64. ²³Na(p, α)²⁰Ne Q_m = 2.377

The first five states of ²⁰Ne have been observed in this reaction, and angular distributions have been measured at E_p = 10.0 and 45.5 MeV: see (1972AJ02).

For work dealing with resonances in the compound nucleus see (1972AJ02), (1974VO09) and ²⁴Mg in (1978EN06). See also (1973AR1F, 1973CL1E; astrophys. considerations).

65. ²³Na(³He, ⁶Li)²⁰Ne Q_m = -1.643

At E(³He) = 40.7 MeV, angular distributions have been measured to ²⁰Ne*(0, 1.63, 4.25) and analyzed using zero-range DWBA (1972OH01).

66. (a) ²⁴Mg(γ, α)²⁰Ne Q_m = -9.3125
(b) ²⁴Mg(p, pα)²⁰Ne Q_m = -9.3125
(c) ²⁴Mg(α, 2α)²⁰Ne Q_m = -9.3125

For reaction (a) see (1973CL1E; astrophys.). For reaction (b) see (1970LI08, 1975ST1Q). See also (1975BA2H), (1975RO1B) and (1975PA1K, 1977CH02; theor.). At E_α = 90 MeV ²⁰Ne states at E_x = 0, 1.63 ± 0.035, 4.25 ± 0.06, 5.70 ± 0.06, 6.72 ± 0.05 and 11.41 ± 0.05 MeV are populated: the ground states S_α (DWIA) = 1.3 ± 0.2 (1976SH02).

67. ²⁴Mg(d, ⁶Li)²⁰Ne Q_m = -7.839

Angular distributions have been studied involving ²⁰Ne*(0, 1.63, 4.25) at E_d = 28 MeV (1972CO23), 35 MeV (1976CO15; also ²⁰Ne*(5.62, 5.78)), 54.3 MeV (1977TA1D; also ²⁰Ne*(5.62 + 5.78)) and 80 MeV (1974DJ01; also ²⁰Ne*(5.62)). Using zero-range DWBA, (1976CO15) report S_α = 0.21, 0.19, 0.87, 0.26, 0.04 for ²⁰Ne*(0, 1.63, 4.25, 5.62, 5.78). See also (1973FO1A, 1973FO1E, 1974FO1J).

68. ²⁴Mg(³He, ⁷Be)²⁰Ne Q_m = -7.726

Angular distributions involving ⁷Be_g.s. and ⁷Be^*_0.43 and ²⁰Ne*(0, 1.63, 4.25) have been measured at E(³He) = 25.5 MeV (1976PI10) and 70 MeV (1976ST11; also ²⁰Ne*(4.97, 5.62)). Spectroscopic factors from a FRDWBA analysis of the 25.5 MeV data give 1.0, 15.4 and 3.5 [from ⁷Be_g.s. data] and 1.0, 23.4 and 4.3 [from ⁷Be^*_0.43 data] for ²⁰Ne*(0, 1.63, 4.25). The absolute spectroscopic factors for ²⁰Ne_g.s. are 0.67 [⁷Be_g.s.] and 0.63 [⁷Be^*_0.43] (1976PI09, 1976PI10). See also (1973BR1C).

69. ²⁵Mg(d, ⁷Li)²⁰Ne Q_m = -7.920

See (1971MC04).

70. ²⁶Mg(p, t_α)²⁰Ne Q_m = -19.255

See (1967MC06).