A=12C (1980AJ01)

1. (a) ⁶Li(⁶Li, n)¹¹C Q_m = 9.453 E_b = 28.175
(b) ⁶Li(⁶Li, p)¹¹B Q_m = 12.218
(c) ⁶Li(⁶Li, d)¹⁰B Q_m = 2.987
(d) ⁶Li(⁶Li, α)⁸Be Q_m = 20.808
(e) ⁶Li(⁶Li, nα)⁷Be Q_m = 1.908
(f) ⁶Li(⁶Li, pα)⁷Li Q_m = 3.552
(g) ⁶Li(⁶Li, 2α)⁴He Q_m = 20.900

For E(⁶Li) = 1.2 to 2.8 MeV, population ratios of ⁷Be*(0.43), ⁷Li*(0.48) and ¹⁰B*(0.72) (reactions (e), (f) and (c)) remain approximately constant. Simple tunneling or compound nucleus models are not compatible with the data and a direct interaction through long-range tails is suggested (1962MC12). Absolute reaction cross sections at E(⁶Li) = 2.1 MeV are in reasonable agreement with estimates based on barrier penetration. A strong preference for α-emission suggests that the favored mechanism involves interacting clusters (1963HU02). The α₀ yield shows a broad peak at E(⁶Li) ≈ 10 MeV (1970FR06: E(⁶Li) = 4 to 24 MeV). The yield of ⁶Li + ⁶Li → 3α (reaction (g)) for E(⁶Li) = 4 to 20 MeV is dominated by a broad resonance (Γ = 5 MeV) at the Coulomb barrier which is consistent with the formation of a quasimolecular state ⁶Li + ⁶Li with τ ≈ 10^-21 sec (1970FR06). A multiparameter coincidence study of reaction (g) for E(⁶Li) = 2 to 13 MeV shows the importance of direct interactions: the data were fitted assuming an (α + d) cluster structure for ⁶Li and an interaction potential acting only between the two deuterons (1971GA21, 1972GA32). The cross section for reaction (g) rises rapidly for E(⁶Li) = 1.0 to 5.5 MeV. Thermonuclear reaction rates have been calculated for kT values of 10 to 1000 keV (1978NO1E). Cross sections for reaction (e) are reported at E(⁶Li) = 1.6, 3.5 and 5.0 MeV (1977RU06). See also (1975NO1C, 1976FI1F), ⁷Li, ⁷Be, ⁸Be and ¹⁰B in (1979AJ01), ¹¹B and ¹¹C here and (1975AJ02).

2. (a) ⁶Li(⁶Li, ⁶He)⁶Be Q_m = -7.795 E_b = 28.175
(b) ⁶Li(⁶Li, ⁶Li)⁶Li

The elastic scattering (reaction (b)) follows the Mott formula at low energies [≲ 4.0 MeV] (1966PI02: E(⁶Li) = 3.2 to 7.0 MeV). A broad structure is observed in the excitation functions [θ_c.m. = 60° and 90°] at E(⁶Li) ≈ 13 MeV (1973GR34) and ≈ 26 MeV [Γ ≈ 7 MeV] (1971FO08: θ_c.m. = 90°; E(⁶Li) to 34 MeV). The elastic scattering appears to be dominated by absorption (1971FO08). Excitation functions for the transitions to ⁶Li*_3.56 + ⁶Li*_3.56 have been measured for E(⁶Li) = 28.0 to 33.0 MeV (1970NA02: θ_c.m. = 90°) and 28.0 to 36.0 MeV (1973WH02, 1974WH01, 1974WH02; θ_c.m. = 88°) [also ratio of ⁶Li*_3.56 + ⁶Li*_3.56 to formation of ⁶He_g.s. + ⁶Be_g.s. at E(⁶Li) = 28, 32, 34 and 36 MeV]. The latter results have been compared with calculations using microscopic DWBA analysis. See also ⁶He and ⁶Li in (1979AJ01).

3. ⁶Li(⁷Li, n)¹²C Q_m = 20.924

See (1975AJ02).

4. ⁹Be(³He, γ)¹²C Q_m = 26.2793

Excitation functions and angular distribution studies have been carried out by (1972BL17: E(³He) = 1.0 to 6.0 MeV; γ₀, γ₁, γ₂), (1972LI29: 1.5 to 11 MeV; γ₀, γ₁, γ₂, γ₃), (1964BL12: 2 to 4.5 MeV; γ₀, γ₁) and (1974SH01: 3 to 21 MeV (γ₂), to 24 MeV (γ₀), to 26 MeV (γ₁, γ₃)). Observed resonances are shown in Table 12.9 (in PDF or PS).

¹²C*(28.2) appears to be formed by s- and d-wave capture. The γ₀ and γ₂ transitions to the 0⁺ states ¹²C*(0, 7.7) are strong and show a similar energy dependence. A strong non-resonant contribution is necessary to account for the γ₁ yield (1972BL17). The resonance structure reported by (1974SH01) appears to confirm the role of 3p-3h configurations for ¹²C excitations somewhat above the giant resonance region. The γ₃ yield is relatively unstructured (1972LI29, 1974SH01: to E(³He) = 26 MeV). See also (1975AJ02).

5. (a) ⁹Be(³He, n)¹¹C Q_m = 7.558 E_b = 26.2793
(b) ⁹Be(³He, p)¹¹B Q_m = 10.3224
(c) ⁹Be(³He, 2n)¹⁰C Q_m = -5.566

Excitation functions for neutrons [and production cross sections for ¹¹C] have been measured for E(³He) = 1.2 to 10 MeV for several neutron groups: see (1968AJ02, 1975AJ02) for a listing of the earlier references. No sharp structure is observed but there is some suggestion from angular distribution data and excitation functions at forward angles for a broad structure (Γ ≈ 350 keV) at E(³He) ≈ 2 MeV: E_x = 27.8 MeV (1963DU12, 1965DI06). The total cross section for ¹¹C production shows a broad maximum, σ = 113 mb at E(³He) = 4.3 MeV (1966HA21). Polarization measurements have been carried out for E(³He) = 2.1 to 3.9 MeV (1971TH15: n₀, n₁, n₂₊₃: the shapes of the measured angular distributions for n₀ and n₁ show very gradual changes with energy. It is suggested that a significant direct interaction contribution is present (1971TH15). Excitation functions and angular distributions for protons (reaction (b)) have been measured for E(³He) = 1.0 to 10.2 MeV for a number of proton groups: see (1968AJ02, 1975AJ02) for a listing of the earlier references and (1977LI1F: 3 to 6 MeV). No pronounced structures are reported. Polarization measurements have been carried out at E(³He) = 14 MeV (1977IR01; P₀, p₁). For reaction (c) see (1974MO23; to E(³He) = 31 MeV). See also (1974LO1B) and ¹¹B, ¹¹C.

6. (a) ⁹Be(³He, d)¹⁰B Q_m = 1.0918 E_b = 26.2793
(b) ⁹Be(³He, t)⁹B Q_m = -1.0860

Analyzing powers have been measured at E(pol. ³He) = 33.3 MeV for nine proton groups (1976KA23). The cross section for ground state tritons (reaction (b)) increases monotonically for E(³He) = 2.5 to 4.2 MeV (1969OR01: θ = 40°) and then shows a broad maximum at E(³He) ≈ 4.5 MeV (1967EA01: θ = 20°). See also (1976UE01) for continuum measurements. See also (1974LO1B) and ⁹B, ¹⁰B in (1979AJ01).

7. ⁹Be(³He, ³He)⁹Be E_b = 26.2793

The elastic scattering excitation function decreases monotonically for E(³He) = 4.0 to 9.0 MeV (1967EA01: θ = 45°) and 15.0 to 21.0 MeV (1972MC01: θ_c.m. = 90°). At θ_c.m. = 111° a slight rise is observed for E(³He) = 19 to 21 MeV (1972MC01). Polarization measurements have been reported at E(³He) = 18 (1972MC01), 31.4 (1971EN03) and 32.8 MeV (1975BU11; polarized ³He). See also (1976RO1L) and ⁹Be in (1979AJ01).

8. (a) ⁹Be(³He, α)⁸Be Q_m = 18.9126 E_b = 26.2793
(b) ⁹Be(³He, 2α)⁴He Q_m = 19.0045

Excitation functions for the α₀ group for E(³He) = 2 to 10 MeV show evidence of a complex structure at ≈ 4 MeV [E_x ≈ 29.3 MeV] (1978BI15: see also for σ_t and α₀ in the range 2 → 10 MeV). Analyzing powers have been measured at E(pol. ³He) = 33.3 MeV for the groups to ⁸Be*(16.9, 17.6, 19.2) (1976KA23). See also (1974SA1K: 1.3 → 3.2 MeV) and (1976RO1L). Reaction (b) has been studied for E(³He) = 2.9 to 10 MeV (1975RO09, 1977GO16). See also (1979BA27), (1975AJ02) and ⁸Be in (1979AJ01).

9. ⁹Be(³He, ⁶Li)⁶Li Q_m = -1.895 E_b = 26.2793

Excitation functions measured for E(³He) = 4 to 10 MeV show some fluctuations: see (1975AJ02). See also ⁶Li in (1979AJ01).

10. ⁹Be(α, n)¹²C Q_m = 5.7015

Neutron groups have been observed to ¹²C*(0, 4.4, 7.7, 9.6, (10.1), (10.8)). Angular distributions of neutron groups have been measured at many energies in the range E_α = 1.75 to 23 MeV: see (1968AJ02, 1975AJ02) for references.

The mean life of ¹²C*(4.4) [J^π = 2⁺] is 57⁺²³_-17 fsec, Γ_γ = 11.5⁺⁵_-3.2 meV (1966WA10). ¹²C*(7.7) decays predominantly into ⁸Be + α: J^π = 0⁺. See also Table 12.8 (in PDF or PS), (1978LO1C), (1974LO1B), (1978MC1F; applied work) and ¹³C in (1981AJ01).

11. ⁹Be(⁶Li, t)¹²C Q_m = 10.485

At E(⁹Be) = 26 MeV, θ_lab = 10°, the population of ¹²C*(0, 4.4, 7.7, 9.6, 10.8, 11.8) is reported: the strongest transition is to ¹²C*(9.6) (1975VE10). See also (1975AJ02).

12. ⁹Be(⁹Be, ⁶He)¹²C Q_m = 5.102

At E(⁹Be) = 26 MeV, θ = 10°, strong transitions are observed to ¹²C*(4.4, 7.7, 9.6) (1975VE10).

13. ¹⁰Be(³He, n)¹²C Q_m = 19.467

At E(³He) = 13 MeV neutron groups are observed to ¹²C*(0, 4.4, 7.7, 16.1, 17.8) and to excited states at E_x = 23.53 ± 0.04 [Γ < 0.4 MeV] and 27.611 ± 0.020 MeV. The latter is formed with a 0° cross section of ≈ 200 μb/sr and is taken to be the first 0⁺, T = 2 state of ¹²C (1974GO23).

14. ¹⁰B(d, γ)¹²C Q_m = 25.1875

The (d, γγ) excitation function [via the J^π = 1⁺, T = 1 state at E_x = 15.1 MeV] has been measured for E_d = 2.655 to 2.91 MeV. The non-resonant yield of 15 MeV γ-rays is due to direct capture process or to a very broad resonance: no sharp resonances are observed corresponding to the T = 2 state reported in reaction 4 [Γ_d₀Γ_γ/Γ ≲ 0.2 eV] (1970BL09, 1974HA1G). See also (1975AJ02).

15. ¹⁰B(d, n)¹¹C Q_m = 6.466 E_b = 25.1875

The thin-target excitation function in the forward direction in the range E_d = 0.3 to 4.6 MeV shows some indication of a broad resonance near E_d = 0.9 MeV. Above E_d = 2.4 MeV, the cross section increases rapidly to 210 mb/sr at 3.8 MeV, and then remains constant to 4.6 MeV (1954BU06, 1955MA76). Excitation functions have also been measured for E_d = 3.2 to 9.0 MeV: see (1975AJ02). The branching ratios at 90° for the transitions to the ground states of ¹¹C and ¹¹B[n₀/p₀] have been measured for E_d = 1.0 to 2.0 MeV by (1973BR24).

Polarization measurements have been carried out for E_d = 1.20 to 4.0 MeV: see (1975AJ02). See also (1969WO09), (1974LO1B), (1977YO1F; applied) and ¹¹C.

16. ¹⁰B(d, p)¹¹B Q_m = 9.2306 E_b = 25.1875

Yields of protons have been measured for E_d = 0.14 to 12 MeV: see (1968AJ02, 1975AJ02). No clear resonance structure is observed. There is some indication that a broad resonance, corresponding to ¹²C*(27.1) affects the p₁ and p₃ yields (1964BR1A). Upper limits for the partial widths (p₀ → p₃) of the T = 2 state reported in reaction 4 are given by (1970BL09).

Polarization studies have been carried out for E_d = 1.15 to 21 MeV: see (1968AJ02, 1975AJ02). See also ¹¹B.

17. ¹⁰B(d, d)¹⁰B E_b = 25.1875

The yield of elastically scattered deuterons has been measured for E_d = 1.0 to 2.0 MeV: resonances at E_d = 1.0 and 1.9 MeV are suggested by (1969LO01). Excitation functions for the deuterons to ¹⁰B*(1.74, 2.16) [J^π; T = 0⁺; 1 and 1⁺; 0, respectively] have been measured at several angles for E_d = 4.2 to 16 MeV: they are characterized by rather broad, slowly varying structures. The ratio σ_1.74/σ_2.15 varies from 0.69 ± 0.04% at E_d = 6.5 MeV to 0.16 ± 0.04% at E_d = 12.0 MeV corresponding, respectively, to isospin impurities of ≈ 2% and ≈ 0.5% (1974ST01). No resonance structure is observed in the elastic yield for E_d = 14.0 to 15.5 MeV (1974BU06). Polarization measurements are reported at E_d = 12.5 MeV (1975ZA08) and at 15 MeV (1974BU06). See also (1977IZ01; theor.) and ¹⁰B in (1979AJ01).

18. (a) ¹⁰B(d, t)⁹B Q_m = -2.179 E_b = 25.1875
(b) ¹⁰B(d, ³He)⁹Be Q_m = -1.0918

For polarization measurements at E_d = 15 MeV involving ⁹Be*(0, 2.43) and ⁹B*(0, 2.36) see (1974LU06). See also ⁹Be and ⁹B in (1979AJ01).

19. (a) ¹⁰B(d, α)⁸Be Q_m = 17.8208 E_b = 25.1875
(b) ¹⁰B(d, 2α)⁴He Q_m = 17.9127

Excitation functions have been measured for the α₀ and α₁ groups for E_d = 0.4 to 12 MeV [see (1968AJ02, 1975AJ02)] and for E_d = 2.5 to 4.5 MeV (1975VA04; α₀) and 0.8 to 9.0 MeV (1978BU04: α₀). Maxima in the α₀ yields are reported at E_d = 1, 2, 4.5 and (6) MeV. The first is attributed to an s-wave resonance corresponding to a state with E_x ≈ 26.0 MeV, Γ ≈ 0.5 MeV (1968FR07). The resonance structures at ≈ 2.0 and 4.5 MeV (Γ ≳ 1 MeV) may both involve the isoscalar giant resonance: E_x ≈ 28 MeV, Γ ≈ 4 MeV (1978BU04). No evidence for the T = 2 state was found in the α₀ and α₁ yield curves taken in 2 keV steps for 27.35 < E_x < 27.65 MeV (1970BL09). For yields of the α particles to ⁸Be*(17.6, 18.1) see (1970CA12) [also discussed in ⁸Be (1959AJ76)]. Reaction (b) has been studied for E_d = 2.7 to 5.0 MeV: see (1975RO09, 1975VA04, 1977GO16) and at E_d = 0.36 MeV (1977NO10). The latter work suggests that a 3^- and a 4⁺ state in ¹²C contribute dominantly to the sequential decay. See also (1976GRZR) and (1979SE04; theor.).

20. ¹⁰B(d, ⁶Li)⁶Li Q_m = -2.987 E_b = 25.1875

See (1975AJ02) and ⁶Li in (1979AJ01).

21. (a) ¹⁰B(³He, p)¹²C Q_m = 19.6940
(b) ¹⁰B(³He, pα)⁸Be Q_m = 12.3273
(c) ¹⁰B(³He, 2p)¹¹B Q_m = 3.7371
(d) ¹⁰B(³He, pn)¹¹C Q_m = 0.973

Proton groups observed by (1958MO99, 1959AL96, 1962BR10) are displayed in Table 12.10 (in PDF or PS). Angular distributions of many of these groups have been measured for E(³He) = 1.4 to 14 MeV: see (1968AJ02).

From studies of ¹⁰B(³He, pα)⁸Be it is determined that ¹²C*(7.7, 9.6, 10.8, 14.1, 16.1) have natural parity π = (-1)^J, and that ¹²C*(11.8, 12.7, 13.4), which decay only to ⁸Be*(2.9) and not to the ground state, have unnatural parity: see Tables 12.8 (in PDF or PS) and 12.10 (in PDF or PS) and (1968AJ02). ¹²C*(12.7) decays also by γ-emission. The charge dependent matrix element connecting ¹²C*(12.7, 15.1) is 110 ± 30 keV (1976AD03, 1977AD02): see also reactions 22, 44, 50, 73, 74 and 86. ¹²C*(16.11, 16.58) show decay to both ⁸Be*(0, 2.9). The consequent assignment of natural parity is consistent with J^π = 2⁺ for the former but not with J^π = 2^- for the latter. For ¹²C*(16.11) observed values of Γ_α₀/Γ are 0.05 - 0.12; the decay to 3α occurs rarely if at all (1966WA16). Table 12.8 (in PDF or PS) summarizes the decay parameters of some of the excited states of ¹²C.

Reactions (c) and (d) have been studied by (1970BO39). The latter, at E(³He) = 11 MeV, appears to proceed via a state in ¹²C at E_x = 20.5 ± 0.1 MeV, which is suggested to be J^π = 3⁺, T = 1. The relative intensities of the decays of ¹²C states with 20 < E_x < 25 MeV via channels (c) and (d) is estimated. The α₀ decay is very small, consistent with the expected population of T = 1 states (1970BO39). See also (1975NA1C), (1975MA21), (1976EP1A; astrophys.), ⁸Be in (1979AJ01) and ¹³N in (1981AJ01).

22. ¹⁰B(α, d)¹²C Q_m = 1.3408

Angular distributions of d₀ and d₁ have been measured at E_α = 15.1 to 25.2 MeV (1975VA19). The relative populations of ¹²C*(12.71, 15.11) [both 1⁺; the latter isospin forbidden] leads to values of ≲ 260 keV (1975SP04), 285 ± 30 keV (1977LI02) for the charge dependent matrix element between these two states: see also reactions 21, 44, 50, 73, 74 and 86. See also (1976GU1B, 1976LE1K). (1978ZE03; theor.) and (1975AJ02).

23. ¹⁰B(⁶Li, α)¹²C Q_m = 23.714

At E(⁶Li) = 4.9 MeV angular distributions have been obtained for the α-particles to ¹²C*(0, 4.4, 7.7, 9.6). The population of ¹²C*(11.8, 12.7) is also reported (1966MC05), as is that of ¹²C*(15.11) [T = 1] (1964CA18: E(⁶Li) = 3.8 MeV): the intensity ratio α_15.1/α_12.7 = 3 ± 2%.

24. ¹⁰B(¹³C, ¹¹B)¹²C Q_m = 6.5088

See (1975SE03, 1975SE04) and ¹¹B.

25. ¹⁰B(¹⁴N, ¹²C)¹²C Q_m = 14.9151

Angular distributions involving ¹²C*_4.4 + ¹²C_g.s. and ¹²C*_4.4 + ¹²C*_4.4 have been measured at E(¹⁴N) = 22.5 and 30 MeV (1969IS01) and 73.9 and 93.6 MeV (1977MO1A). See also (1973ST1A).

26. ¹⁰B(¹⁶O, ¹⁴N)¹²C Q_m = 4.4512

Angular distributions involving ¹⁴N_g.s. + ¹²C_g.s. and ¹⁴N_g.s. + ¹²C*_4.4 have been measured at E(¹⁶O) = 30 and 32.5 MeV and also at 26 MeV for the double ground state transition (1969IS01).

27. (a) ¹¹B(p, γ)¹²C Q_m = 15.9569
(b) ¹¹B(p, α)⁸Be Q_m = 8.5902 E_b = 15.9569
(c) ¹¹B(p, α)⁴He⁴He Q_m = 8.6821

In view of the complexity of the available information on these three reactions, we will first summarize the recent experimental results and then review the evidence for the parameters of ¹²C states observed as resonances.

(a) In the range 4 MeV < E_p < 14.5 MeV σ(γ₀) is dominated by the giant dipole resonance at E_p = 7.2 MeV (E_x = 22.6 MeV, Γ_c.m. = 3.2 MeV), while the giant resonance in γ₁ occurs at E_p ≈ 10.3 MeV (E_x = 25.4 MeV, Γ_c.m. ≈ 6.5 MeV): see (1964AL20). A study of the giant dipole resonance region with polarized protons (E_p = 6 to 14 MeV) sets new limits on the configuration mixing in the γ₀ giant resonance (1972GL01). The E2 strength is found to be centered near E_p = 12 MeV: it exhausts ≳ 30% of the isoscalar E2 sum rule (1976MAZG, 1976MAZL). The analysis of γ₁ is more complicated: the asymmetry results are consistent either with a single J^π = 2^- state or with interference of pairs of states such as (1^-, 3^-), (2^-, 3^-) and (1^-, 2^-) (1972GL01). See also (1979AR1G). Measurements of differential cross sections at 90° (E_p = 13 to 22 MeV), of angular distributions (E_p = 7 and 14 to 21 MeV), and of total cross sections (E_p = 14 to 21 MeV) have been reported by (1972BR26). The 90° yield of γ₀, γ₁, γ₂ and γ₃ [to ¹²C*(0, 4.4, 7.7, 9.6)] has been studied by (1977SN01): the γ₂ yield shows a peak at E_p ≈ 14.3 MeV with a cross section ≈ 2.3% that of γ₀ [in γ₀ yield, E_res = 15.0 MeV (1977SN01), 14.8 MeV (1969KE02)] and perhaps as well a low intensity structure at E_p = 11.8 MeV. The γ₃ yield exhibits two asymmetric peaks at E_p = 12.5 and 13.8 MeV (Γ ≈ 0.7 and 2.5 MeV) and a weaker structure at ≈ 9.8 MeV (1977SN01). The (pγγ) process [via ¹²C*(15.1)] has been studied in the vicinity of the first two T = 2 states; only a non-resonant yield is observed: (2J + 1)Γ_γΓ_p/Γ < 0.25 eV and < 1.5 eV, respectively for ¹²C*(27.4, 28.6) (1977NA1F). At E_p = 40, 60 and 80 MeV, radiative capture is observed to a state, or a narrow group of states, at E_x = 19.2 ± 0.6 MeV (1979KO05). Work on other resonances is reported below.

(b) Excitation functions have been measured for E_p = 3.0 to 8.0 MeV (1975BO1H), 6.53 to 7.32 MeV (1977OH1A; α₀, α₁) and 6.0 to 18.0 MeV (1977BU07; α₀). A wide resonance-like structure centered at E_p = 13 MeV [¹²C*(28)] with Γ ≈ 6 MeV is reported by (1977BU07): the angular distributions of α₀ show prominent back peaking. See also (1978BU1D). Polarization measurements are reported for E_p = 2.62 to 2.66 MeV (1975MA49: α₀).

(c) This reaction has been studied for E_p = 35.4 keV to 10.5 MeV. The total cross section has been measured for E_p = 35.4 to 1500 keV: it shows the 163 keV resonance and a broad peak centered at about 600 keV (σ_max ≈ 0.9 b; read from Fig. 3). The 163 keV resonance has σ_R = 54 ± 6 mb and Γ^R_c.m. = 5.2^+0.5_-0.3 keV, E_res(c.m.) = 149.8 ± 0.2 keV [E_x = 16.1067 (5)]. The astrophysical S-factor and the reaction rate <σν> have been calculated. The values of <σν> obtained in this work suggest that the ¹¹B(p, 3α) reaction may be a poorer candidate for CTR than previously thought (1979DA03). At higher energy the reaction proceeds predominantly by sequential two-body decays via ⁸Be*(0, 2.9): see in ⁸Be (1979AJ01), ¹²C [reaction 25] in (1975AJ02) and (1974KA1J, 1975KR1E, 1975VA04, 1977FU09, 1977GR10, 1977OH1A). Contributions from ¹²C*(23.0, 23.6, 25.4) are also reported (1975VA04).

See also (1976BO08, 1977AV01: spallation), (1977MC1C, 1977TR1E, 1978ZI1A: applications), (1974LO1B, 1976GL1E, 1979BL1J, 1979SN1A) and (1976GA1K, 1977GA1H, 1978GA13, 1979RAZW; theor.).

The parameters of the observed resonances are displayed in Table 12.11 (in PDF or PS). The following summarizes the information on the low-lying resonances: for a full list of references see (1968AJ02).

E_p = 0.16 MeV: [¹²C*(16.11)]. This is the J^π = 2⁺; T = 1 analog of the first excited states of ¹²B and ¹²N. The γ-decay is to ¹²C*(0, 4.4, 9.6), and also ¹²C*(12.71) [see Table 12.8 (in PDF or PS)]: the angular distribution of γ₃, together with the known α-decay of ¹²C*(9.6), fix J^π = 3^- for the latter (1961CA13). A new measurement of the (p, γ) and (p, α) resonant cross sections yields 125 ± 16 μb and 38.5 ± 3.2 mb, respectively, based on Γ_c.m. = 6.7 keV. Γ_γ and Γ_p for ¹²C*(16.11) are then 21.7 ± 3.3 eV and 21.7 ± 1.8 eV, respectively (1974AN19). (1977AD02) report Γ_γ₀ = 0.75, Γ_γ₁ = 16.2, and Γ_γ₇ = 0.24 eV: see, however, Table 12.8 (in PDF or PS).

E_p = 0.67 MeV: [¹²C*(16.58)]. The proton width [Γ_p ≈ 150 keV] indicates s-wave protons and therefore J^π = 1^- or 2^-. This is supported by the near isotropy of the two resonant exit channels, α₁ and γ₁. The α₁ cross section indicates 2J + 1 ≥ 5: therefore J^π = 2^-. [This is consistent with the results of an α - α correlation study via ⁸Be*(2.9) (1972TR07).] The γ₁ E1 transition has |M|² ≈ 0.1 W.u., suggesting T = 1 (1957DE11, 1965SE06).

E_p = 1.4 MeV: [¹²C*(17.23)]. (2J + 1)Γ_γ₀ ≥ 115 eV. This indicates J^π = 1^-, with T = 1 most probable (1965SE06). J^π = 1^- is also required to account for the interference at lower energies in α₀ and γ₀ [see (1957DE11)] and is consistent with the α - α correlation results of (1972TR07). Two solutions for Γ_p are possible; the larger (chosen for Table 12.11 (in PDF or PS)) is favored by elastic scattering data (1965SE06). See, however, (1975KR1E).

E_p = 2.0 MeV: [¹²C*(17.8)]. The resonance in the yield of α₀ requires natural parity, the small α-widths suggest T = 1. For J^π = 1^- or 3^- the small γ-widths would be surprising; J^π = 2⁺ would lead to a larger anomaly than is observed. J^π is then 0⁺, T = 1 (1965SE06).

E_p = 2.37 MeV: [¹²C*(18.13)]. Seen as a resonance in the yield of 15.1 MeV γ-rays: σ_R = 0.77 ± 0.15 μb, Γ_c.m. = 600 ± 100 keV, (2J + 1)Γ_γ ≥ 2.8 ± 0.6 eV. The results are consistent with J^π = 1⁺, T = 0, but interference with a non-resonant background excludes a definite assignment (1972SU08).

E_p = 2.62 MeV: [¹²C*(18.35)]. The resonance for α₀ requires natural parity; the presence of a large P₄ term in the angular distribution requires J ≥ 2 and l_p ≥ 2. The assignment J^π = 3^- is consistent with the data (1965SE06, 1972CH35, 1972VO01, 1974GO21).

E_p = 2.66 MeV: [¹²C*(18.40)] is not seen here: see ¹¹B(p, p).

E_p = 3.12 MeV: [¹²C*(18.80)]. The angular distribution of γ₀ indicates E2 radiation, J^π = 2⁺. This assignment is supported by the angular correlation in the cascade γ₁ and by the behavior of σ(α₀); T = 1 is suggested by the small Γ_α (1965SE06).

The structure near E_p = 3.5 - 3.7 MeV [¹²C*(19.2, 19.4)] seems to require at least two levels. The large Γ_γ₀ requires that one be J^π = 1^-, T = 1 and interference terms in σ(α₀) require the other to have even spin and even parity: J^π = 2⁺; T = 0 is favored (1963SY01, 1965SE06). Resonances at E_p = 4.93 and 5.11 MeV, seen in σ(γ₁) (1955BA22) also appear in σ(α₁), but not in σ(α₀). Angular distributions suggest J^π = 2⁺ or 3^- for the latter [¹²C*(20.64)]; the strength of γ₁ and absence of γ₀ favors J^π = 3^-, T = 1 (1963SY01).

The first seven T = 1 states in ¹²B and ¹²C have been identified by comparing reduced proton widths obtained for this reaction and reduced widths obtained from the (d, p) and (d, n) reactions: see Table 12.12 (in PDF or PS) (1971MO14, 1974AN19). See also (1977AD02).

28. ¹¹B(p, n)¹¹C Q_m = -2.764 E_b = 15.9569

Excitation functions have been reported for E_p = 2.6 to 11.5 MeV. They are characterized by numerous peaks: see Table 12.13 (in PDF or PS). The positions of these appear to correspond with ¹¹B(p, α)⁸Be and with some of the (γ, n) and (γ, p) structure, suggesting that resonances, and not fluctuations, are involved. Angular distributions do not change as rapidly as might be expected from the pronounced structure in the excitation function (1965OV01).

Polarization transfer coefficients for n₀-bar have been measured for E_p-bar = 7.3 to 14.8 MeV (1976LI08) and 16.3, 21.3 and 26.5 MeV (1976HI11). The lower energy work shows a strong peak at E_p-bar = 9 MeV (1976LI08). (1976HI11) find that the results are not in agreement with direct reaction theory calculations using a charge-exchange effective interaction which includes both central and tensor forces. See also (1974MA07; theor.) and (1975AJ02). See also ¹¹C, (1977ME1C), (1977YO1G, 1979OV1A; applications), (1976WA1B) and (1977GA1H, 1978DE37; theor.).

29. (a) ¹¹B(p, p)¹¹B E_b = 15.9569
(b) ¹¹B(p, p')¹¹B*
(c) ¹¹B(p, 2p)¹⁰Be Q_m = -11.2287
(d) ¹¹B(p, d)¹⁰B Q_m = -9.2306

Anomalies and maxima observed in the excitation functions of p₀ and p₁ are displayed in Table 12.13 (in PDF or PS). Recent studies are reported at E_p = 1.8 to 3.1 MeV (1975MA49, 1976MA64; p₀), E_p-bar = 1.9 to 3.0 MeV (1977MA37; p₀), E_p = 3.0 to 5.2 MeV (1977RI01; p₀), 3 to 8 MeV (1975BO1H: prelim.; p₀ → p₃), 7.5 to 10.5 MeV (1975VA04; p₀, p₁) and 19.2 to 47.4 MeV (1978NA03; σ_t).

Polarization measurements have been carried out at a number of energies for E_p = 1.9 to 155 MeV: see (1975AJ02). (1977MO09) have observed polarization transfer in order to study the spin-flip process at E_p-bar = 32 MeV: the cross section is lower than that predicted by DWBA. See also (1975MA1H, 1976PH01, 1977PH02; theor.). For reactions (c) and (d) see ¹⁰Be, ¹⁰B in (1979AJ01).

30. ¹¹B(d, n)¹²C Q_m = 13.7323

Reported neutron groups are displayed in Table 12.14 (in PDF or PS). Angular distributions have been studied in the range 0.5 < E_d < 11.8 MeV: see (1968AJ02, 1975AJ02) for a listing of the references. See (1971MU18) for a discussion of the problems involved in comparing spectroscopic factors obtained in this reaction and in the (³He, d) reaction [reaction 31]. Angular correlation studies involving ¹²C*(4.4, 15.1) have been carried out at many energies in the range 0.7 < E_d < 6.3 MeV.

In the range E_d = 1.0 to 5.5 MeV, two slow neutron thresholds are observed at 1.627 ± 0.004 MeV (E_x = 15.109 ± 0.005 MeV) and near 4.1 MeV (broad; E_x = 17.2 MeV) (1955MA76). At the lower threshold, 15.1 MeV γ-rays are observed: E_d = 1.633 ± 0.003 MeV, Γ < 2 keV (1958KA31) [E_x = 15.110 ± 0.003 MeV].

A study of the angular distributions and energy spectra of α-particles from the decay of ¹²C states shows that the 12.71 and 11.83 MeV states decay sequentially via ⁸Be; the former via ⁸Be*(2.9), the latter 90% via ⁸Be*(2.9) and 10% via ⁸Be(0). There is some evidence that the 10.84 MeV state decays primarily to ⁸Be(0). J^π = 3^- for the 9.64 MeV state is favored on the basis of the angular distribution of the α-particles to ⁸Be(0). There is no evidence for direct 3α decay of ¹²C levels in the range E_x = 9 to 13 MeV, nor does ¹²C*(10.3) appear to participate in this reaction (1965OL01). See also (1978GR07) and ¹³C in (1981AJ01).

31. (a) ¹¹B(³He, d)¹²C Q_m = 10.4634
(b) ¹¹B(³He, np)¹²C Q_m = 8.2388

Observed deuteron groups are displayed in Table 12.14 (in PDF or PS). Angular distributions have been measured at E(³He) = 5.1 to 44 MeV [see (1975AJ02)] and at E(³He) = 23.2 MeV (1977KA1R: d to ¹²C*(12.71, 15.11)). ¹³N*(15.1) [T = 3/2] has been observed to decay to ¹²C*(9.6, 10.8) with branching ratios of (9.6 ± 1.4)% and (16.4 ± 3.6)% respectively (1979AD01). See also ¹³N in (1981AJ01).

32. ¹¹B(α, t)¹²C Q_m = -3.8571

Angular distributions have been measured at five energies in the range E_α = 15.1 to 46 MeV [see (1975AJ02)], at E_α = 25.1 MeV (1974DM01: t₀, t₁) and at 120 MeV (1979CHZP). The (t₁, γ) angular correlations have been measured for E_α = 21.2 to 25.0 MeV (1972EL09). See also (1976GU1B, 1976LE1K) and (1978ZE03; theor.).

33. ¹¹B(⁷Li, ⁶He)¹²C Q_m = 5.982

See (1968ST12).

34. ¹¹B(¹⁴N, ¹³C)¹²C Q_m = 8.4063

Angular distributions have been measured for the ground state transition at E(¹⁴N) = 41, 77 and 113 MeV: they show damping of the oscillations with increasing energy (1971LI11).

35. ¹¹B(¹⁶O, ¹⁵N)¹²C Q_m = 3.8294

Angular distributions have been measured at E(¹⁶O) = 27, 30, 32.5, 35 and 60 MeV for the transitions ¹⁵N_g.s. + ¹²C_g.s., ¹⁵N*_6.3 + ¹²C_g.s., ¹⁵N_g.s. + ¹²C*_4.4 and ¹⁵N_g.s. + ¹²C*_9.6 (the latter at E = 60 MeV only) (1972SC03): at the highest energy the ratio θ²/θ²_g.s. for the transition ¹¹B_g.s. + p → ¹²C is 0.12 and 0.05, respectively for ¹²C*(4.4, 9.6). See also (1975SC35) and (1974FL1A, 1975OS01, 1976DE08, 1977GO1D, 1977WE1H; theor.).

36. ¹²B(β^-)¹²C Q_m = 13.370

The decay is mainly to ¹²C_g.s.; branching ratios to ¹²C*(0, 4.4, 7.7, 10.3) are displayed in Table 12.15 (in PDF or PS). All the observed transitions are allowed. The half-life is 20.20 ± 0.02 msec (1978AL01). See also Table 12.2 (in PDF or PS) of (1968AJ02).

¹²C*(7.7) is of particular interest for helium burning processes in stars [see (1968AJ02)]. The fact that the β-decay is allowed indicates J^π = 0⁺, 1⁺ or 2⁺; it decays primarily by α-emission eliminating J^π = 1⁺, and requiring 0⁺. (1973BA73) have measured the Q of the α-decay of ¹²C*(7.7) to be 379.6 ± 2.0 keV. When this result is combined with the Q determined from accurate measurements of the E_x of ¹²C*(7.7), the "best" value is Q = 380.1 ± 1.1 keV. This value, together with previously measured values of Γ_π, Γ_π/Γ and Γ_rad/Γ lead to Γ_rad = 3.41 ± 1.12 meV and to a mean lifetime for the destruction of helium by the [ααα] process of 2.59 x 10^-8ρ²T^-3₉exp(-4.411/T⁹) sec^-1 (1973BA73). See, however, Table 12.8 (in PDF or PS). A search for transitions to ¹²C*(12.7) has been unsuccessful (1967AL03).

(1978LE02) have measured the alignment correlation term which leads to α_-(E₀) = -(1 ± 2)%/MeV; (1978BR01) find α_- = +(0.24 ± 0.44)%/MeV. The shapes of the β-spectra of ¹²B and ¹²N have both been analyzed [see reaction 69]. The values for α_- - α₊ are all now in agreement with the predictions of CVC and with the absence of second class currents: see, e.g., (1977KA24, 1977SU1F, 1977WU01, 1978MO02, 1979KO12).

37. ¹²C(γ, γ)¹²C

Resonance scattering and absorption by ¹²C*(15.11) have been studied by many groups: see Table 12.15 (in PDF or PS) in (1968AJ02) and (1970AH02, 1976ME25). The partial widths are displayed in Table 12.8 (in PDF or PS). Elastic scattering to ¹²C*(4.4, 16.1, 17.2) has also been observed. The E_x of ¹²C*(4.4) is 4439.4 ± 1.6 keV (1977WE1C). Rayleigh scattering has been studied at θ = 1.02° for E_γ = 0.4 to 3 MeV by (1978KA1P) and nuclear Thomson scattering for E_γ = 5.5 to 7.2 MeV (1977BE32: θ = 140°). At higher energies elastic scattering studies show the giant resonance peak at ≈ 24 MeV. A considerable tail is visible, extending to > 40 MeV (1959PE32). See also (1975RO1N, 1976VE06, 1977CR1C, 1977HA1W, 1979KA1Q), (1975BR1F), (1975AJ02) and reaction 38.

38. (a) ¹²C(γ, n)¹¹C Q_m = -18.721
(b) ¹²C(γ, 2n)¹⁰C Q_m = -31.846

The total absorption, mainly (γ, n) + (γ, p), is dominated by the giant resonance peak at 23.2 MeV, Γ = 3.2 MeV [σ_max = 21 mb (1975AH06)] and by a smaller structure at 25.6 MeV, Γ ≈ 2 MeV [σ_max ≈ 13 mb (1975AH06)]: see (1968AJ02, 1975AJ02) for a detailed listing of the earlier references and results. The attenuation coefficient of 6.42 MeV γ-rays has been measured by (1975MO27).

The (γ, n) cross section shows a giant resonance centered at about 22.5 MeV, Γ ≈ 3 MeV (σ_max ≈ 8 mb), a secondary maximum at 25.5 MeV, Γ ≈ 2 MeV, and a long tail: see (1966FU02, 1966LO04, 1975KN10), (1975BE1F, 1976BE1H) and (1968AJ02). The (γ, n₀) cross section has been measured at 90° for 21 < E_x < 40 MeV and compared with the (γ, p₀) cross section (1968WU01): the isospin mixing averages about 2% in intensity and shows structure at the giant resonance. Angular distributions of n₀ measured over the giant resonance region indicate that the main excitation mechanism is of a 1p_3/2 → 1d_5/2 E1 single particle character. No significant E2 strength is observed (1968RA21). See also (1975AJ02), ¹¹C and (1975SC05). The production cross section of ¹¹C by 30 MeV electrons is 11.92 ± 0.15 μb: this corresponds to an electric dipole (γ, n) integrated cross section to 30 MeV of 41.0 ± 0.6 MeV · mb (1978KL03). Pair production by 6.6 MeV γ-rays in carbon has been studied by (1976RO1N).

The cross section for reaction (b) has been measured for E_γ = 35 to 130 MeV. The (γ, 2n) cross section is very much smaller than that for (γ, n): the highest value is 0.15% of the maximum value for reaction (a) in the energy range E_γ = 20 to 140 MeV (1970KA37). The ¹⁰C production cross section has been measured for E_bs = 100 to 800 MeV (1977JO02). See also (1975NO10, 1975WO04, 1977BA3D, 1977HI12), (1974BU1A, 1975BE60, 1977DA1B, 1979BO1U), (1976WA1J; applications) and (1975WO07, 1976HE12, 1977GR08, 1977WU02, 1978KA1Q; theor.).

39. (a) ¹²C(γ, p)¹¹B Q_m = -15.9569
(b) ¹²C(γ, π⁺)¹²B Q_m = -152.936
(c) ¹²C(γ, π^-)¹²N Q_m = -156.905

The photoproton cross section exhibits two broad peaks, the giant resonance peak at 22.5 MeV, Γ = 3.2 MeV, σ_max = 13.1 ± 0.8 mb and a 2 MeV broad peak at 25.2 MeV, σ_max = 5.6 ± 0.3 mb: see (1976CA21) and Table 12.19 (in PDF or PS) in (1968AJ02). While the E1 component dominates in the GDR, a 2% E2 contribution may possibly be present (1976CA21). In contrast with the giant resonance peak in the (γ, n) cross section, the (γ, p) cross section shows a strong peak in the center of the broad giant resonance peak. Above 24.5 MeV the ground state (γ, p) and (γ, n) excitation functions have the same shape up to at least 36 MeV (E.G. Fuller, private communication). There is agreement between the (γ, p) results and those from the inverse reaction ¹¹B(p, γ₀)¹²C [see reaction 27] when the population of ¹¹B*(4.4, 5.0) is taken into account. See also (1975AJ02). The fraction of transitions to the ground and excited states of ¹¹B have been determined at several energies in the range E_bs = 24.5 to 42 MeV: most of the transitions are to ¹¹B_g.s. and the excited state transitions appear to originate from localized E_x regions (1970ME17). The cross sections for (γ, p₀) and (γ, p₀ + p₁) have been measured at E_γ = 60, 80 and 100 MeV (1976MA34). See also ¹¹B and (1978KI03).

(1978BA50) have studied the momentum distribution of π⁺ and π^- for E_γ = 300 to 850 MeV and (1978AR08) have measured the cross section for π^- production in the range 510 to 750 MeV. The cross section for π⁺ production, summed over ¹²B states, has been measured for E_bs to 175 MeV (1979MI06). See also the "Pion capture and pion reactions" section here, (1976BE39, 1979BOZW, 1979PA06, 1979SH1N) and (1975AJ02). See also (1975TO10, 1976KU1C, 1977AL33, 1977AL1P, 1977KI1J, 1979AL1T), (1976GA02) and (1975AN1H, 1975BI05, 1975FU07, 1976HE12, 1977FI12, 1977NE2A, 1978FI10, 1978FU09, 1978WO11; theor.).

40. (a) ¹²C(γ, d)¹⁰B Q_m = -25.1875
(b) ¹²C(γ, pn)¹⁰B Q_m = -27.4122

Cross sections and angular distributions of the deuterons corresponding to transitions to ¹⁰B_g.s. and/or low excited states have been measured at E_γ ≈ 40 MeV: the results are consistent with E2. There is some evidence also for the excitation of higher states of ¹⁰B via non-E2 transitions (1972SK08). For E_bs = 90 MeV, the ratio of yields of deuterons to protons is ≈ 2%, for particle energies 15 to 30 MeV. For higher particle energies, the ratio decreases (1962CH26). For reaction (b) see (1975AJ02).

41. (a) ¹²C(γ, t)⁹B Q_m = -27.366
(b) ¹²C(γ, ³He)⁹Be Q_m = -26.2793

The yield of tritons has been measured for E_γ = 35 to 50 MeV by (1967KR05). For reaction (b) see (1969TA11).

42. ¹²C(γ, α)⁸Be Q_m = -7.3667

The cross section exhibits broad peaks at about 18 MeV and ≈ 29 MeV; a pronounced minimum occurs at 20.5 MeV: to what extent the peaks have fine structure is not clear: see (1964TO1A) and (1968AJ02). For E_γ < 22 MeV, transitions are mainly to ⁸Be_g.s. and ⁸Be*(2.9) with the g.s. transition dominating for E_γ ≲ 14 MeV. For E_γ > 26.4 MeV, ⁸Be (T = 1) levels near 17 MeV are strongly excited (1955GO59). Alpha energy distributions show surprisingly strong E1 contributions below E_γ ≈ 17 MeV (1955GO59, 1964TO1A). See also (1976TU05, 1979FL1G) and (1978DZ01, 1978MY1B; theor.).

43. (a) ¹²C(γ, pα)⁷Li Q_m = -24.6222
(b) ¹²C(γ, nα)⁷Be Q_m = -26.2665

The yield of 0.48 MeV γ-rays from the decay of ⁷Be, formed in reaction (b), shows a resonance at E_γ ≈ 29.5 MeV, σ = 0.9 ± 0.2 mb (1969OW01). For work on the γ-induced spallation of ¹²C see (1968AJ02, 1975AJ02) and (1976TU05).

44. ¹²C(e, e)¹²C

The nuclear charge radius of ¹²C, R_rms = 2.472 ± 0.002 fm (1979CA1G). Other values include R_rms = 2.445 ± 0.015 fm (Fermi model), 2.453 ± 0.008 fm (shell model) (1972JA10), 2.462 ± 0.022 fm (1973FE13), 2.45 ± 0.04 fm (1979DO1M). See also (1975AJ02). Elastic scattering has been studied up to 4 GeV: see (1968AJ02, 1975AJ02).

¹²C states observed in inelastic scattering are displayed in Table 12.16 (in PDF or PS). The variation of the form factor F(q²) with momentum transfer yields unambiguous assignments of J^π = 2⁺, 0⁺ and 3^- for ¹²C*(4.4, 7.7, 9.6): see (1975AJ02) and (1978CR1A, 1979CR1D, 1979FL1F). The isospin mixing between the 1⁺ states ¹²C*(12.7, 15.1) has been measured by (1974CE01): β = 0.19 ± 0.01 or 0.05 ± 0.01. See also reactions 21, 22, 50, 73, 74 and 86. A study at E_e = 57 to 215 MeV (θ = 180°) of the transverse form factors squared of the 2⁺ states ¹²C*(4.4, 16.1) indicates appreciable contributions of nuclear convection currents to the T = 0 state at low momentum transfer and spin magnetization contributions to the T = 1 state at higher q (1978FL09). Longitudinal and transverse form factors of ¹²C*(16.1) have been studied by (1978FR03) at E_e = 32.8 to 62.2 MeV. The ground state branching ratio for ¹²C*(17.76) is < 10^-9 (1979CR1D).

Inelastic scattering of the giant resonance has been studied by many groups: see (1968AJ02) and Table 12.16 (in PDF or PS). The longitudinal form factors show ¹²C*(16.1, 18.6, 20.0, 21.6, 22.0, 23.8, 25.5) while the transverse form factors show ¹²C*(15.1, 16.1, 16.6, 18.1, 19.3, 19.6, 20.6, 22.7, (25.5)) (1970AN1C, 1970TO13, 1971YA03, 1972AN03). ¹²C*(19.3) may be the expected giant magnetic quadrupole state, J^π = 2^-: see (1975AJ02). See also (1978FA1F, 1979FL1F).

45. (a) ¹²C(e, ep)¹¹B Q_m = -15.9569
(b) ¹²C(e, en)¹¹C Q_m = -18.721
(c) ¹²C(e, eπ⁺)¹²B Q_m = -152.936
(d) ¹²C(e, eπ^-)¹²N Q_m = -156.905

Electron spectra in the region of large energy loss show a broad peak which is ascribed to quasi-elastic processes involving ejection of single nucleons from bound shells: see (1968AJ02). Studies of e' - p coincidences for E_e = 497 to 700 MeV reveal peaks corresponding to ejection of 1p and 1s protons: the energy of the two peaks [Γ = 6.9 ± 0.1 and 19.8 ± 0.5 MeV] are 15.5 ± 0.1 and 36.9 ± 0.3 MeV (1976NA17: 700 MeV; DWIA). By studying the missing energy spectrum at E_e = 497 MeV (1976MO17) the population of ¹¹B*(2.14, 5.0) [as well as of ¹¹B_g.s. (1974BE12)] is reported. See also (1975AJ02) and (1977ZI1B). The deep inelastic response function has been studied by (1978MO19: E_e = 160 to 520 MeV, θ = 60° and 130°): a pronounced transverse strength is found in the region between the quasielastic and the N peaks.

For reaction (b) see (1975WO04) and (1975AJ02). For reaction (c) see (1977SH14) and ¹²B. For reaction (d) see (1976HE13). For both see also the "Pion capture and pion reactions" section here.

46. (a) ¹²C(π^-, π^-)¹²C
(b) ¹²C(π⁺, π⁺)¹²C
(c) ¹²C(π^-, π⁺π^-π^-)¹²C

Angular distributions of the scattering (primarily elastic at forward angles) have been measured at E_π = 29 MeV (1978JO09; π^-), 29.2 and 49.5 MeV (1979GY1B; π^-), 50 MeV (1977DY02, 1978MO25, 1979DY02; π⁺), 120 to 280 MeV (1970BI1A; π^-), 125 MeV (1979NA04; π⁺), 162 MeV (1978MO23; π⁺) and 150, 162, 226 MeV (1977PI02, 1977PI09, 1979CH05; π⁺ and π^-). Inelastic distributions to ¹²C*(4.4, 9.6) are reported by (1977DY02; E_π⁺ = 50 MeV), (1970BI1A; E_π^- = 120 to 280 MeV; also to ¹²C*(15.0)), (1979CH05; also to 7.7; E_π⁺ = E_π^- = 162 MeV), (1978TH1C; E_π^- = 162 MeV) and (1978MO23; E_π⁺ = 162 MeV; also to 19.3). Observation of 4.4 MeV γ-rays at E_π = 73 MeV leads to a cross section ratio (π^-/π⁺) of 1.23 ± 0.22. The cross section is 14.5 ± 3.0 mb for π⁺ (1970HI10). At E_π⁺ = 148 MeV, ¹²C*(7.6, 15.1) are also populated (1978PE11). See also (1977GR1G, 1979MOZW). (Comparison of π⁺ and π^- inelastic scattering at E_π = 180 MeV shows structures at E_x ≈ 19.2 - 19.7 MeV which may be due in part to an isospin-mixed 4^- doublet (1979CO1N). Angular distributions have been reported at E_π⁺ = 100 to 300 MeV for ¹²C*(4.4, 7.7, 9.6, 19.3) (1979AL1U). Preliminary values for the isospin mixing of ¹²C*(12.71, 15.11) and ¹²C*(18.4, 19.4) are 125 ± 35 and 250 ± 50 keV, respectively (1979BO2D, 1979MO1W; prelim.; E_π = 116, 180 MeV). See also (1979CO1L).) The absorption cross section at E_π⁺ = 125 MeV is 161 ± 28 mb (1979NA04). The emission of 2 photons in the capture of stopped pions, i.e. (π^-, γγ), occurs at a rate of ≈ (1.3 ± 0.3) x 10^-5/capture (1979DE06). See also (1977RO21, 1979MA2J). For the (π⁺, π⁺p) reaction see (1978CO02). For reaction (c) see (1973AS1A). See also the "Pion capture and pion reactions" section here.

47. (a) ¹²C(n, n)¹²C
(b) ¹²C(n, n)⁴He⁴He⁴He Q_m = -7.2748
(c) ¹²C(n, nd)¹⁰B Q_m = -25.1875

Elastic and inelastic scattering to ¹²C*(4.4, 7.7, 9.6, 10.3, 10.8, 11.8) have been studied at many energies up to 350 MeV: see (1968AJ02) and Table 12.19 (in PDF or PS) in (1975AJ02). Recent angular distribution measurements have been reported at E_n = 1.5 to 4.0 MeV (1975HO1G, 1978SM1D; n₀, natural C), 8.0 to 14.5 MeV (1978HA1P; n₀, n₁), 8.97 to 14.93 MeV (1976GL11; n₀, n₁), 14.2 MeV (1978ME12; n₀, n₁), 14.2 MeV (1978DR03; n₁γ) and 14.6 MeV (1975KO27; n₀). Angular correlations (n₁, γ_4.4) have been studied at E_n = 13.9 to 15 MeV: see (1975AJ02). For a brief discussion of studies of the spin-flip probability for the transition to ¹²C*(4.4) see (1975AJ02). See also ¹³C in (1976AJ04, 1981AJ01).

At E_n = 14.4 MeV reaction (b) involves ¹²C*(9.6, 10.8, 11.8, 12.7): see (1975AJ02, 1976CO1N). For reaction (c) see (1978RI02). See also (1975AN1J, 1975AN1G, 1975HO1F, 1975JE01, 1975PO08, 1976HA1N, 1977WHZZ), (1976MC1E, 1976WA1B, 1978FU1G) and (1976CA13, 1976TH10, 1977NO07, 1978AD1A; theor.).

48. ¹²C(p, p)¹²C

Angular distributions of elastically and inelastically scattered protons have been measured at many energies up to E_p = 1040 MeV: see Tables 12.22 (in PDF or PS) in (1968AJ02), 12.20 (in PDF or PS) in (1975AJ02) and 12.17 (in PDF or PS) here.

Table 12.18 (in PDF or PS) displays the information on excited states of ¹²C. The newly reported value of E_x = 7654.00 ± 0.20 keV leads to a Q-value for the decay of this state into 3α of 379.31 ± 0.21 keV (1976NO02) and J. Nolen, private communication): this implies an increase of 9%, at a stellar temperature of 10⁸° K, in the 3α reaction rate calculated by (1975FO19). A summary of the information on the decays of this and other excited states of ¹²C is shown in Table 12.8 (in PDF or PS).

The spin-flip probability (SFP) for the transition to ¹²C*(4.4) has been measured for E_p = 15.9 to 37.6 MeV: two bumps appear at ≈ 20 and ≈ 29 MeV. It is suggested that the lower one is due to a substructure of the E1 giant dipole resonance while the upper one results from the E2 giant quadrupole resonance (1975DE32). See also the studies listed in (1975AJ02). SFP has also been measured for ¹²C*(12.71) at E_p = 42 MeV (1977MO18) and for ¹²C*(12.7, 15.1) for E_p = 23.5 to 27 MeV (1978HOZJ). The relative population of ¹²C*(12.7, 15.1) has been measured at E_p = 800 MeV, θ = 5.8°: it is roughly 1 : 2 (1978BO1Q).

The angular distributions of the proton groups to ¹²C*(4.4, 12.7, 15.1) for E_p = 22.5 to 45 MeV have been analyzed by (1975GE15) to obtain the structures of the giant resonances. It is suggested that the E2 strength is fragmented, with the major concentration, corresponding to the isoscalar E2 resonance, near 28 MeV, and subsidiary strength near 32 and 42 MeV, the latter possibly a part of the isovector quadrupole resonance. See also the structures reported by (1977BU19) and displayed in Table 12.18 (in PDF or PS).

For polarization measurements see ¹³N in (1976AJ04, 1981AJ01). See also (1975KA2D, 1976FR05, 1977BR33, 1977DY1C, 1977SP1D, 1979BLZY, 1979BU1D), (1975IG1A, 1976SL2A, 1977AL1U, 1977SP1B, 1978AL1G, 1978ER1C,1978IG1B, 1979LI06), (1976CR1D; astrophys.), (1978GO1E; applied) and (1974SA1G, 1974SC1E, 1975AH1C, 1975AH03, 1975AH1E, 1975BR14, 1975CL1D, 1975DU1A, 1975FR13, 1975GU11, 1975MA23, 1975NA07, 1975SC1T, 1975ST1M, 1975VI09, 1976AB05, 1976BU01, 1976HO1E, 1976KO1G, 1977AH04, 1977AL15, 1977AL19, 1977GU1D, 1977GU1E, 1977KH02, 1977KO1T, 1977NE06, 1977PH02, 1977SU1E, 1977VI03, 1977WE1K, 1978BE64, 1978BE1Y, 1978BE66, 1978CO1J, 1978FA04, 1978GU12, 1978KO32, 1978LE06, 1978MA34, 1978RA20, 1979AB01, 1979AM02, 1979BO03, 1979DY1E, 1979JA1L, 1979PEZX; theor.).

49. (a) ¹²C(p, 2p)¹¹B Q_m = -15.9569
(b) ¹²C(p, pn)¹¹C Q_m = -18.721
(c) ¹²C(p, pd)¹⁰B Q_m = -25.1875
(d) ¹²C(p, pt)⁹B Q_m = -27.366
(e) ¹²C(p, p³He)⁹Be Q_m = -26.2793
(f) ¹²C(p, pα)⁸Be Q_m = -7.3667
(g) ¹²C(p, d³He)⁸Be Q_m = -25.7199

The (p, 2p) reaction has been studied at energies up to 1 GeV: see (1975AJ02) for the earlier work, ¹¹B and (1976BH02, 1977KO08, 1977NA16, 1977NA29, 1978KO30). See also (1978CH1K, 1979KRZX). For reaction (b) see (1975AJ02), (1976HO19) and ¹³N in (1981AJ01). For reaction (c) see ¹⁰B in (1979AJ01), (1977GR04) and ¹³N in (1981AJ01). See also (1978AZ1B). For reactions (d, e) see (1976GR1H, 1977GR04).

At E_p = 56.5 MeV reaction (f) proceeds primarily by sequential α-decay: initially ¹²C*(19.7 ± 0.5, 21.1 ± 0.3, 22.2 ± 0.5, 26.3 ± 0.5) are formed. These states, which must therefore have natural parity and a significant T = 0 admixture, subsequently decay to ⁸Be_g.s. [¹²C*(22.2, 26.0)] or ⁸Be*(2.9) [¹²C*(19.7, 21.1, 26.3)] (1969EP01). At E_p = 100 MeV reactions (f) and (g) to ⁸Be_g.s. have been studied by (1977CO07, 1977RO02): <S_α> = 0.59 ± 0.05 and 0.56 ± 0.12, respectively. For reaction (f) see also ⁸Be and (1978CH1H, 1978DE1J, 1978LA11). For pion production see (1978PE12).

50. (a) ¹²C(d, d)¹²C
(b) ¹²C(d, pn)¹²C Q_m = -2.2246
(c) ¹²C(d, dα)⁸Be Q_m = -7.3667

The angular distribution of elastically and inelastically scattered deuterons has been studied at many energies up to E_d = 650 MeV: see (1968AJ02), Table 12.22 (in PDF or PS) in (1975AJ02) and Table 12.17 (in PDF or PS) here. E_x of ¹²C*(4.4) is 4440.5 ± 1.1 keV (1974JO14). The isospin mixing of ¹²C*(12.7, 15.1) [J^π = 1⁺; T = 0 and T = 1] gives a mean charge dependent matrix element of 324 ± 33 keV (1977LI02: E_d = 24.1 to 28.8 MeV). See also (1976COYZ), (1975AJ02) and reactions 21, 22, 44, 73, 74 and 86. The quadrupole deformation parameter is calculated to be β₂ = -0.48 ± 0.02 independent of incident energy [E_d = 60.6, 77.3, 90.0 MeV] (1975AS06; coupled channels analysis). (1971DU09) report β₂ = 0.47 ± 0.05 and β₃ = 0.35 ± 0.06 for ¹²C*(4.4, 9.6) [E_d = 80 MeV].

In addition to the well-known states of ¹²C, (1975AS06) report the population of states with E_x = 18.3 ± 0.3, 20.6 ± 0.3 and 21.9 ± 0.3 MeV [broad], of a broad maximum at ≈ 27 MeV, and possibly also of states at E_x = 10.8 ± 0.2 and 11.8 ± 0.2 MeV. (1977CH1L) report two structures at E_x = 26 ± 1 and 29 ± 1 MeV, with Γ = 2 ± 1 and 4 ± 1 MeV, and determine L = 3 in the excitation of ¹²C*(18.4).

Reaction (b) has been studied in a kinematically complete experiment at E_d = 5.00 to 5.50, 9.20 and 9.85 MeV by (1973SA03) and also at E_d = 5.1 to 6.5 MeV [see the discussion in (1975AJ02)]. See also ¹³C and ¹³N in (1976AJ04). For pion production see (1977BR33, 1978PE12). See also ¹⁴N in (1976AJ04, (1981AJ01). See also (1975KI1G, 1979AZ1B), (1974AD1B, 1975SC1V) and (1974CH58, 1975GU10, 1975MA23, 1976CH03, 1977DM1A, 1977KU07, 1977VA03, 1978GH03, 1978HA1Q, 1978MA34, 1978NI1A, 1978ZE03, 1979CH06, 1979LA02; theor.). For reaction (c) see (1979HE06).

51. ¹²C(t, t)¹²C

Angular distributions of elastically scattered tritons have been determined at E_t = 1.0 to 20.04 MeV: see (1975AJ02).

52. ¹²C(³He, ³He)¹²C

Angular distributions of ³He ions have been measured in the range E(³He) = 2 to 217 MeV: see (1968AJ02), Table 12.22 (in PDF or PS) in (1975AJ02) and Table 12.17 (in PDF or PS) here. Parameters of observed ³He groups are displayed in Table 12.19 (in PDF or PS).

Angular distributions of the ³He groups to ¹²C*(15.11, 16.11, 16.58, 19.56) have been compared with those for the tritons to ¹²N*(0, 0.96, 1.19, 4.25) in the analog (³He, t) reaction: the correspondence is excellent and suggests strongly that these are T = 1 isobaric analog states (1969BA06: E(³He) = 49.8 MeV). See also Tables 12.12 (in PDF or PS) and 12.19 (in PDF or PS). The states reported by (1977BU03) at E(³He) = 130 MeV [see Table 12.19 (in PDF or PS)]: ¹²C*(4.4, 15.2, 18.4, 18.9, 21.3, 23.5, 25.9, 28.8) are all stated to correspond to E2 transitions: their strengths add up to 46% of the EWSR (energy-weighted sum rule). The quadrupole deformation parameter β₂ = 0.30 can account for both the elastic and inelastic data providing that the ratio of the s.o. and central deformation β_s.o./β_cent is energy dependent (E(³He) = 20.5 - 33 MeV) (1977KA25). See also (1975AJ02). For pion production see (1976WA10).

See also ¹⁵O in (1976AJ04, 1981AJ01), (1975AU01), (1976RO1L, 1978BE1H) and (1974CH58, 1974KU15, 1975MA23, 1977DM1A, 1977GE1E, 1977KU07, 1978ZE03; theor.).

53. (a) ¹²C(α, α)¹²C
(b) ¹²C(α, 2α)⁸Be Q_m = -7.3667
(c) ¹²C(α, ⁸Be)⁸Be Q_m = -7.4586

Angular distributions have been measured at many energies up to 1.37 GeV: see Tables 12.24 (in PDF or PS) in (1968AJ02), 12.22 (in PDF or PS) in (1975AJ02) and 12.17 (in PDF or PS) here. Parameters of observed states of ¹²C are displayed in Table 12.19 (in PDF or PS). J^π assignments have also been suggested for ¹²C states with 9.6 ≤ E_x ≤ 39.3 MeV on the basis of their decay into 3α-particles: see (1973JA02; E_α = 90 MeV). The quadrupole deformation, β₂, is -0.29 ± 0.02 (1971SP08), -0.30 ± 0.02 (1976PA05), 0.4 (1977BU19), 0.46 (1973SM03); β₃ = 0.24 (1973SM03), 0.23 (1977BU19).

Angular correlation measurements (α₁γ_4.4) have been carried out for E_α = 10.2 to 104 MeV: see (1975AJ02, 1978AL20, 1978RI03). See also (1976AL23, 1976GU1B). The relative population of magnetic substates has been studied by (1970HA15, 1972BU09). Alpha-alpha correlations from ¹²C*(14.1) to ⁸Be_g.s. lead to an assignment of J^π = 4⁺ for that state (1977MC07). See also (1978RI03).

At E_α = 104 MeV, the sum of the E2 strength in the dominant decay channels [α₀ + α₁ + p₀] for 20 < E_x < 30 MeV exhausts less than 15% of the EWSR (energy-weighted sum rule) (1978RI03). At E_α = 150 MeV, the observed isoscalar E2 strength is (6 ± 2)% of EWSR (1976KN05). See also (1976KIZN). The yields of the 12.71 and 15.11 γ-rays have been measured for E_α = 22 to 27 MeV: strong structures are observed [see ¹⁶O]. The yield of γ_15.1 is 1 to 20% of that for γ_12.7 (1975SP04). Measurements of the radiative widths for ¹²C*(7.7, 9.6) are reported in Table 12.8 (in PDF or PS) (1974CH32, 1976MA46).

Reaction (b) has been studied for E_α up to 700 MeV: see (1975AJ02). See also (1977YA1A, 1979DO04). For pion production see (1976WA10, 1977BR33, 1978PE12). For reaction (c) see (1976WO11).

54. (a) ¹²C(⁶Li, ⁶Li)¹²C
(b) ¹²C(⁷Li, ⁷Li)¹²C

The elastic scattering in reaction (a) has been studied at E(⁶Li) = 4.5 to 40 MeV [see (1975AJ02)], at 4.5 to 13 MeV (1976PO02), 50.6 MeV (1976CH27) and 59.8 MeV (1975BI06; also to ¹²C*(4.4, 7.7)), and at E(pol. ⁶Li) = 20 and 22.8 MeV (1976WE10). See also (1977SC1B: E(⁶Li) = 100 MeV) and (1976WE10, 1978DR07, 1978MA13) in ¹⁸F (1978AJ03, 1983AJ01). (1974BI04: E(⁶Li) = 36.4 and 40 MeV) have measured the inelastic angular distributions to ¹²C*(4.4, 7.7, 9.6, 10.8, 11.8, 12.7, 13.4, 14.1) and have calculated deformation parameters under various assumptions. For the α-decay of ¹⁶O states see (1977CU1B).

The elastic scattering in reaction (b) has been studied at E(⁷Li) = 4.5 to 36 MeV [see (1975AJ02)], at 4.5 to 13 MeV (1976PO02), 36 MeV (1976CO23) and at 89 MeV (1979BR04; also to ¹²C*(4.4); β²₂ = 0.51 ± 0.02). See also (1978DR07) in ¹⁹F (1983AJ01). See also (1971SC21, 1975GR41, 1976OG1A, 1978FI1E) and (1975TH1C, 1976AM01, 1976ST22, 1977KU07, 1978MA1B, 1978ME14, 1978NO08, 1978PE1C, 1979BE59; theor.).

55. ¹²C(⁹Be, ⁹Be)¹²C

Elastic scattering angular distributions have been obtained at E(⁹Be) = 14, 20 and 26 MeV (1979JA04, 1979UN01), 39.7 and 43.8 MeV (1979MA21; also to ¹²C*(4.4)) and at E(¹²C) = 12, 15, 18 and 21 MeV (1970BA49). For excitation function measurements see (1978MA44); for fusion cross sections see (1978CH02). See also (1976ECZZ, 1977IG1D, 1977PE1B), (1976OG1A, 1978TA1B) and (1978PA1B; theor.).

56. (a) ¹²C(¹⁰B, ¹⁰B)¹²C
(b) ¹²C(¹¹B, ¹¹B)¹²C

Elastic angular distributions for reaction (a) have been measured at E(¹⁰B) = 18 MeV (1968VO1A, 1969VO10) and 100 MeV (1975NA15, 1977TO02; also to ¹²C*(4.4, 9.6)). Elastic angular distributions in reaction (b) have been studied at E(¹²C) = 15, 17, 20 and 24 MeV (1974BO15), 16, 18, 22 and 24 MeV (1975DU11) and 87 MeV (1971LI11) and at E(¹¹B) = 28 MeV (1968VO1A, 1969VO07, 1969VO10; also to ¹²C*(4.4) as well as to several ¹¹B states). See (1978FR20) for differential cross section measurements in the range E(¹¹B) = 18.8 to 34.1 MeV and (1976ST12, 1977HI02) for fusion cross section measurements. See also (1973BR1C, 1975AJ02), (1976AR1H, 1978RO1D; astrophys.) and (1975RE04, 1978AV1A, 1978VA1A; theor.).

57. ¹²C(¹²C, ¹²C)¹²C

Angular distributions have been measured at E(¹²C) = 10 to 20 MeV (1977HI1D, 1977KO1Q, 1977KO1W, 1978ER1D: g.s.), 10 to 37.6 MeV (1973EM03, 1975EM01: g.s. + g.s., g.s. + 4.4, 4.4 + 4.4), 17.6 to 27.5 MeV (1977CI01: g.s.), 40 to 60 MeV (1973WI09: g.s. + g.s., g.s. + 4.4), 30 to 50 MeV (1978CO20: g.s.), 70 MeV (1971KO11, 1975KO1E: g.s., 4.4, 4.4 + 4.4, 9.6), 70.7 to 126.7 MeV (1976WI14, 1977ST1Q, 1979ST10: g.s., 4.4, ((4.4 + 4.4) + 9.6)), 87 MeV (1971LI11: g.s.), 98.2 MeV (1977ST1Q: 7.65, 9.64, 14.07), and 114 and 174 MeV (1973AN22: g.s., 4.4, 7.7, 9.6, 14.1, 19.6).

The relative population of elastic and inelastic channels is very energy dependent: see, e.g., (1975AJ02) and (1975EM02, 1977BR18, 1977CI01, 1977CO05, 1977CO1P, 1977KO1Q, 1977KO1V, 1977KO1X, 1978CA1K, 1978CO20, 1978ER1D, 1978JA1D, 1979CL06). Total cross sections at 1.55 and 2.89 GeV/c/A are reported by (1978JA16). See also (1976SP07, 1978CO1L, 1978KO1L, 1978SA05, 1979COZS, 1979HA1P, 1979HEZX, 1979NA02) and (1974FO1F, 1978RO1D, 1978RO1L; astrophys.) and (1974VE05, 1975FR13, 1976AR14, 1976CU03, 1976CU07, 1976MA45, 1976ZI01, 1977AB1B, 1977BA3E, 1977CH11, 1977CI1C, 1977CL1D, 1977FI1C, 1977FR1H, 1977FR12, 1977FR1L, 1977KI1L, 1977LO1H, 1977PA28, 1977PA1H, 1977RO1K, 1977SA09, 1977SA10, 1977WA1Q, 1978AB1C, 1978AR1H, 1978AV1A, 1978BE1R, 1978BI1G, 1978CH10, 1978DA1G, 1978FI1G, 1978FR1F, 1978FR1H, 1978FR1N, 1978KO14, 1978SC1G, 1978SC1E, 1978TA13, 1978TA1P, 1978TA1B, 1978TA19, 1978TA1T, 1978TO12, 1978VA1G, 1978VA1A, 1978WI05, 1979AB02, 1979CH06, 1979CO06, 1979GO1P, 1979HA07, 1979HE1H, 1979KO11, 1979LAZY, 1979MO1J, 1979NA03, 1979PH01, 1979PI03, 1979TA02, 1979TA1K; theor.).

58. (a) ¹²C(¹³C, ¹³C)¹²C
(b) ¹²C(¹⁴C, ¹⁴C)¹²C

Angular distributions for reaction (a) have been studied at E(¹²C) = 15, 19, 20 → 36 and 87 MeV [see (1975AJ02)] and at E(¹²C) = 20.0 to 35.5 MeV (1978CH29: g.s. and 4.4 - the latter from 30 MeV) and E(¹³C) = 12 MeV (1976WE28, 1977GU07: g.s.) and 36 MeV (1976WE21: g.s.). Elastic angular distributions in reaction (b) are reported at E(¹²C) = 12 to 20 MeV (1972BO68). For yield measurements see (1975AJ02) and (1976ST12, 1976WE28, 1977GE1G, 1978CH29, 1978LE1N). See also (1974GO1L, 1975VO1B, 1977WI1C), (1978RO1D; astrophys.) and (1975DE09, 1977IM1A, 1977TR1A, 1978AV1A, 1978CH30, 1978IM1A, 1978PA1B, 1978TA1B; theor.).

59. (a) ¹²C(¹⁴N, ¹⁴N)¹²C
(b) ¹²C(¹⁵N, ¹⁵N)¹²C

Angular distributions have been measured at E(¹⁴N) = 21 to 88 MeV [see (1975AJ02)], 37 to 58.3 MeV (1978CO20: g.s.) and at 53 MeV (1976ZE04: g.s.), 65, 84 and 88 MeV (1971KO11, 1975KO1E: g.s., 4.4, 9.6) and 155 MeV (1975NA11, 1975NA15, 1977TO02: g.s., 4.4, 9.6). See also (1977MO1A) and ¹⁴N in (1976AJ04). For fusion cross sections see (1976ST12, 1977KO1V, 1977SW02, 1978CO20, 1979GO09, 1979GO11). Reaction (b) has been studied for E(¹⁵N) = 31.5 to 47 MeV (1978CO20). See also (1977PH1C). See also (1978DA1E), (1975VO1B, 1976LE1F, 1978TS04), (1978RO1D; astrophys.) and (1975DE09, 1975MO23, 1975RA33, 1976AM01, 1977BA3E, 1977MA11, 1978AV1A, 1978CU1C, 1978CU1E, 1978CU06, 1978FR1N, 1978HO13, 1978KA14, 1978VA1A, 1979NA03; theor.).

60. (a) ¹²C(¹⁶O, ¹⁶O)¹²C
(b) ¹²C(¹⁶O, α)¹²C¹²C Q_m = -7.1620

Angular distributions have been measured at E(¹⁶O) = 20 to 168 MeV [see (1971AJ02, 1975AJ02, 1977AJ02)] and at E(¹⁶O) = 17.29 to 23.14 MeV (1976CH13), 30.8 to 33.9 MeV (1978SC06), 31.7 to 52.7 MeV (1978JA1H; also ¹²C*(4.4) from 46 MeV), 46 MeV (1976SP01; also involves various states in ¹⁶O), 52.0 MeV (1977SH16; also excited ¹⁶O states), 55.3, 56.7, 65.8 MeV (1978KA13; also excited ¹⁶O states), 59.6 to 61.2 MeV (1978SH01; not g.s.: ¹²C*(4.4)), 65 and 80 MeV (1973GU12; also ¹²C*(4.4) and excited ¹⁶O states), 84 MeV (1978BO11; only ¹²C*(4.4)), 80 to 122 MeV (1977CO20), and at 315 MeV (1979DO01; not g.s.: ¹²C*(4.4, 14.1, 25.3 - 26.7)), and at E(¹²C) = 65 MeV (1978BO11; also ¹²C*(4.4)) and 76.8 MeV (1977MO1A, 1977MO1H). See also (1978MA1R) and ¹⁶O in (1977AJ02, 1982AJ01).

(1979DO01) present evidence for the excitation of giant resonances in a number of nuclei including ¹²C: ¹²C*(25.3 - 26.7) (Γ ≈ 4 MeV) contain 25⁺¹⁵_-10% of the E2 strength. (1978BO11) have measured the m-state populations in the transition to ¹²C*(4.4) at E(¹²C) = 65 MeV and E(¹⁶O) = 84 MeV. See also (1977DE1P). For reaction (b) see (1974WI05, 1979FU02, 1979SC10). See also (1975AJ02).

For fusion cross section measurements see (1976CU04, 1976EY01, 1976FR20, 1976SP03, 1977BR38, 1977KO1V, 1977NA23, 1978CH15, 1978FE04, 1978TA11, 1979KO03). For other yield measurements see (1975SH24, 1976CH13, 1976SP01, 1977CO20, 1977TA03, 1978JA04, 1978KA13, 1978MA22, 1978MA32, 1978SC06, 1978SH01, 1979FRZX, 1979FU02, 1979JAZY, 1979TA05). See also (1978MA1R). A number of resonances are observed. See also ²⁸Si in (1978EN06).

61. (a) ¹²C(¹⁷O, ¹⁷O)¹²C
(b) ¹²C(¹⁸O, ¹⁸O)¹²C

The elastic scattering angular distributions have been measured at E(¹⁷O) = 30.5 and 33.8 MeV (1978CH03) and 35 MeV (1967GO1A) and at E(¹⁸O) = 32.3 and 35 MeV (1978CH03), 35 MeV (1967GO1A) and 47.5, 55 and 57.5 MeV (1976WE05). Fusion cross sections have been measured for E(¹⁷O) = 16.9 to 33.8 MeV (1976EY01) and 34 to 80 MeV (1978HE18) and for E(¹⁸O) = 17.5 to 35.0 MeV (1976EY01), 50 MeV (1978HE18) and 100 MeV (1978CO07). See also (1976SP07, 1978CH03, 1978FR05, 1979CH07, 1979GAZV: yieldmeasurements), (1974GO1L, 1978LE1T, 1978TS04) and (1977BA3E, 1978BI1G, 1978PA1B, 1978VA1A, 1979KR07, 1979NA03, 1979PAZY; theor.).

62. ¹²C(¹⁹F, ¹⁹F)¹²C

Elastic scattering angular distributions have been measured at E(¹⁹F) = 40, 60 and 68.8 MeV (1968VO1A, 1969VO10, 1972SC03). See also (1976SP07, 1977KO38: fusion cross section at E(¹⁹F) = 92 MeV), (1973BR1C, 1975GR41, 1975VO1B) and (1977BA3E, 1978BI1G, 1978HO13, 1978VA1A, 1979NA03; theor.).

63. (a) ¹²C(²⁰Ne, ²⁰Ne)¹²C
(b) ¹²C(²²Ne, ²²Ne)¹²C

Elastic angular distributions for reaction (a) have been measured at E(¹²C) = 37 MeV (1974VA18) and E(²⁰Ne) = 65.7 MeV (1975DO06, 1978DO01). For yield measurements see (1977CO1Q, 1977PR1F, 1978DO01, 1979FOZY). See also (1977SC1G), (1978RO1L; astrophys.) and (1976VA12, 1977OS02, 1978VO06; theor.).

64. (a) ¹²C(²⁴Mg, ²⁴Mg)¹²C
(b) ¹²C(²⁶Mg, ²⁶Mg)¹²C

See (1978CL1E, 1979DAZT). See also (1978TA1B, 1979TA1K; theor.).

65. ¹²C(²⁷Al, ²⁷Al)¹²C

The angular distribution of the transition to ¹²C*(4.4) has been measured at E(¹²C) = 82 MeV (1977BE42). See also (1977SC1G) and (1978VA1A; theor.).

66. ¹²C(²⁸Si, ²⁸Si)¹²C

Elastic angular distributions have been studied at E(¹²C) = 19 to 36 MeV (1977CH25), 24, 27 and 30 MeV (1977EC04), 40.2 MeV (1975RA33), 49.3, 70 and 83.5 MeV (1971KO11) and 186.4 MeV (1977DE23) and at E(²⁸Si) = 58.3 to 116.7 MeV (1978CL02, 1979OS01). For yield measurements see (1978BA02, 1978CL02, 1979KUZX). See also (1978TA1B) and (1977ZI1C, 1979TA1K; theor.).

67. ¹²C(³²S, ³²S)¹²C

Elastic angular distributions are reported at E(¹²C) = 35.8 MeV (1978GE14) and E(³²S) = 73.3 to 128.3 MeV (1979OS01: back angles).

68. (a) ¹²C(⁴⁰Ca, ⁴⁰Ca)¹²C
(b) ¹²C(⁴¹Ca, ⁴¹Ca)¹²C
(c) ¹²C(⁴²Ca, ⁴²Ca)¹²C
(d) ¹²C(⁴⁸Ca, ⁴⁸Ca)¹²C

The elastic scattering in reactions (a), (c) and (d) has been studied at E(¹²C) = 51.0, 49.9 and 49.9 MeV, respectively (1979RE03). See also (1979OS01). For reaction (b) see (1978BA26; theor.). For yield measurements see (1978RE06, 1979KU02, 1979RE03).

69. ¹²N(β⁺)¹²C Q_m = 17.338

The decay is mainly to the ground state via an allowed transition. Branching ratios to other states of ¹²C are displayed in Table 12.20 (in PDF or PS). The half-life of ¹²N is 11.000 ± 0.016 msec (1978AL01). See also the earlier values in Table 12.28 (in PDF or PS) of (1968AJ02). Since transitions to ¹²C*(0, 4.4) are allowed J^π(¹²N) = 1⁺.

A recent measurement of the ratio of the branching ratios ¹²N/¹²B for the decays to ¹²C*(4.4) is R = 1.56 ± 0.05 (1978AL01). This leads to the following values for the mirror asymmetries of ¹²B and ¹²N for decay to ¹²C*(0, 4.4): δ_4.4 = +0.044 ± 0.034, δ_g.s. = +0.129 ± 0.008 (1978AL01). See also (1975AJ02) for earlier measurements. These values in turn lead to second class current (SCC) contributions δ₀^SCC = -0.006 ± 0.038 and δ₁^SCC = -0.047 ± 0.037, which are consistent with zero (1978AL01).

The shapes of the β-spectra of ¹²B and ¹²N have been analyzed to give the following values for α_- - α₊: (+0.98 ± 0.09)%/MeV (1977KA24), (+0.86 ± 0.24)%/MeV (1977WU01) and (+0.302 ± 0.062)%/MeV (1977SU1F). (1978BR18) find α₊ = -0.273 ± 0.039%/MeV in agreement with the results of (1977SU1F: -0.277 ± 0.052%/MeV), These measurements are in agreement with CVC and with the absence of second class induced tensor currents. See also (1976CA29, 1978MO02, 1979KO12; theor.). See also (1975SU01, 1976SU1C, 1977DE11), (1973MIYZ, 1974AD1B, 1976BE1E, 1977GA1E, 1977RI08, 1977TE1B, 1978CA1H, 1978LE02, 1978RA2A, 1978WE1J, 1979DO1A) and (1975BE24, 1975DO10, 1975DO1D, 1975KU20, 1975MO1F, 1975RH1A, 1975WI1E, 1976KH05, 1976MO1G, 1976SU09, 1976YO1D, 1977BE2A, 1977HW01, 1977KU1E, 1977OK1A, 1977WA1F, 1977YA1D, 1978BE1V, 1978BE58, 1978KU1A, 1978MO02, 1978SE1B, 1978SZ07, 1979DE15, 1979SZ02; theor.).

70. ¹³C(γ, n)¹²C Q_m = -4.9464

The decay of the giant resonance in ¹³C takes place predominantly to ¹²C*(15.1, 16.1) [and their analogues in ¹²B]. Below E_γ = 21 MeV transitions to ¹²C*(0, 4.4) are dominant (1975PA09). See also (1976CR1C, 1977WO04), (1977MA06; theor.), (1975AJ02) and ¹³C in (1981AJ01).

71. ¹³C(π⁺, p)¹²C Q_m = 135.403

At E_π⁺ = 34 MeV the population of ¹²C*(4.4) is more than 10 times that of ¹²C_g.s. (1978DO1F). See also (1975HU1D; theor.).

72. (a) ¹³C(p, d)¹²C Q_m = -2.7218
(b) ¹³C(p, pn)¹²C Q_m = -4.9464

Angular distributions of the d₀ and d₁ groups to ¹²C*(0, 4.4) have been measured at E_p = 8, 12, 17, 50 and 54.9 MeV [see (1975AJ02)], 16.7 and 17.7 MeV (1977GU14) and 200 to 500 MeV (1979KA1R). See also (1978BA1R, 1978IG1A; prelim.: 650 and 800 MeV) and (1979CA1A). Angular distributions have also been measured for the groups to ¹²C*(12.7, 15.1, 16.1) at E_p = 50 MeV (1970SC02) and 54.9 MeV (1968TA08). ¹²C*(14.1) is not excited, consistent with J^π = 4⁺ (1970SC02, 1974PA01). At E_p = 62 MeV, (1974PA01) report the excitation of states with E_x = 15112 ± 5, 16110 ± 5 [< 20], 17760 ± 20 [80 ± 20], 18800 ± 40 [80 ± 30], 21500 ± 100 [< 200] and 22550 ± 50 [< 200] keV [the numbers shown in brackets are Γ_c.m., in keV]: l_n = 1 for all states except ¹²C*(21.5) and (22.55) for which l_p = (1) and ≠ 1, respectively. Spectroscopic factors are derived by (1968TA08, 1970SC02, 1974PA01): see (1977AD02).

In a kinematically complete experiment at E_p = 7.9 to 12.5 MeV, it is found that sequential decay via states in ¹³C and ¹³N is strongly involved in reaction (b). Near E_p = 12.5 MeV there is some indication of sequential decay via singlet deuteron formation (1971OT02). See also (1975AJ02), ¹³C, ¹³N, ¹⁴N in (1981AJ01) and (1978MA34; theor.).

73. ¹³C(d, t)¹²C Q_m = 1.3109

Angular distributions have been studied at E_d = 0.41 to 28 MeV [see (1975AJ02)] and at E_d-bar = 13 MeV (1978DA17: t₀, t₁, t₂), E_d = 24.1, 26.2 and 27.5 MeV (1977LI02: t to ¹²C*(12.71, 15.11, 16.11) and E_d-bar = 29 MeV (1979CO08: t to ¹²C*(0, 4.4, 12.71, 15.11, 16.11); see also ¹³C(d, ³He) in ¹²B). (1977LI02) find an isospin mixing parameter, β, of 0.07 ± 0.03 for the two 1⁺ states ¹²C*(12.71, 15.11) and a charge-dependent matrix element of 180 ± 80 keV (1977LI02), 120 ± 30 keV (1979CO08); both are lower than the value previously obtained in this reaction, 250 ± 50 keV (1972BR27). If the j = 1/2 component is excluded, which appears to be unwarranted, the charge dependent matrix element is 140 ± 40 keV (1979CO08). See also reactions 21, 22, 44, 50, 74 and 86. See also ¹⁵N in (1981AJ01) and (1975ZA06, 1977AD02).

74. (a) ¹³C(³He, α)¹²C Q_m = 15.6314
(b) ¹³C(³He, 2α)⁸Be Q_m = 8.2647

Angular distributions have been measured at many energies up to E(³He) = 45 MeV [see (1968AJ02, 1975AJ02)] and at 18 and 20 MeV (1977AD07; α₀, α₁) and 29.2 MeV (1976FU1F; α₁). Angular correlations of α-particles and 4.4 MeV γ-rays have been studied at E(³He) = 4.5 MeV (1962HO13) and 29.2 MeV (1976FU1F) and for αγ_15.1 at 9.4 and 11.2 MeV (1969TA09).

A study of reaction (b) leads to Γ_α/Γ for ¹²C*(15.11) = 4.1 ± 0.9%; together with the other parameters for the decay of the state (see Table 12.8 (in PDF or PS)) this leads to Γ_α = 1.8 ± 0.3 eV. If this isospin forbidden α-width is the result of the mixing between the 1⁺ states ¹²C*(12.71, 15.11) [T = 0 and 1, respectively] via a charge dependent interaction, the matrix element is 340 ± 60 keV (1974BA42). See also reactions 21, 22, 44, 50, 73 and 86. For the decay of ¹²C*(12.7, 15.1) see Table 12.8 (in PDF or PS) (1970RE09). See also (1976STYX, 1978SM1B) and (1977TA06; theor.).

75. (a) ¹³C(⁶Li, ⁷Li)¹²C Q_m = 2.3041
(b) ¹³C(⁷Li, ⁸Li)¹²C Q_m = -2.9137

At E(⁷Li) = 34 MeV angular distributions have been observed for the reactions to ¹²C*(0, 4.4) + ⁷Li*(g.s., 0.48) and ⁸Li*(0, 0.95) in all combinations. While ¹²C*(0, 4.4) are dominant in the two spectra, ¹²C*(7.7, 9.6) and, in reaction (a) at E(⁶Li) = 36 MeV, ¹²C*(12.7) are also populated (1973SC26).

76. ¹³C(¹³C, ¹⁴C)¹²C Q_m = 3.2302

See (1979KOZZ).

77. ¹³C(¹⁴N, ¹⁵N)¹²C Q_m = 5.8870

See (1975SE03, 1975SE04).

78. (a) ¹³C(¹⁶O, ¹⁷O)¹²C Q_m = -0.8021
(b) ¹³C(¹⁷O, ¹⁸O)¹²C Q_m = 3.0982
(c) ¹³C(¹⁸O, ¹⁹O)¹²C Q_m = -0.9894

Angular distributions for reaction (a) have been measured at E(¹⁶O) = 13 and 14 MeV (1976DU04), 14, 17 and 20 MeV (1968KN1A, 1971BA68) and 41.7 and 46.0 MeV (1973DE21). See also (1975SE03). Angular distributions for reaction (b) are reported at E(¹⁷O) = 29.8 and 32.3 MeV (1977CH22, 1978CH16) while reaction (c) has been studied at E(¹⁸O) = 15, 20 and 24 MeV (1971BA68, 1971KN05) and 31.0 MeV (1978CH16). In all cases the ¹²C_g.s. is involved as well as various states in the residual nucleus: see ¹³C in (1981AJ01), ¹⁷O in (1982AJ01) and ¹⁸O in (1978AJ03, 1983AJ01) and ¹⁹O in (1978AJ03, 1983AJ01). See also (1978PA1D, 1978SC1E; theor.).

79. ¹³C(¹⁹F, ²⁰F)¹²C Q_m = 1.6548

See (1975SE03, 1975SE04).

80. ¹⁴C(p, t)¹²C Q_m = -4.6410

Angular distributions have been measured at E_p = 14.5, 18.5 and 39.8 MeV: see (1975AJ02). At E_p = 54 MeV angular distributions are reported to two states at E_x = 27.57 ± 0.03 and 29.63 ± 0.05 MeV [Γ_c.m. ≲ 200 keV]: their identification as the first T = 2 states is supported by the similar angular distributions to the first two T = 2 states in ¹²B, reached in the (p, ³He) reaction [see reaction 20 in ¹²B]. The lower T = 2 state is well fitted by L = 0; the angular distribution to ¹²C*(29.63) is rather featureless. It is suggested that its shape is somewhat more consistent with L = 0 than with L = 2 (1976AS01). [(1976BA24) has suggested that the second T = 2 state in A = 12 may have J^π = 0⁺.] It is not excluded that the group to ¹²C*(29.63) may be due to unresolved states (1976AS01). (1976AS01) report Γ_p/Γ ≈ 0.3 ± 0.1 and Γ_α₁/Γ < 0.1 for the first T = 2 state and Γ_p/Γ = 0.8 ± 0.2, Γ_p₀/Γ ≈ 0.4 and Γ_α/Γ ≈ 0.2 for ¹²C*(29.63). (1978RO08) report E_x = 27595.0 ± 2.4 keV, Γ ≤ 30 keV for the first T = 2 state and calculate the decay properties for two values of total width, 0 and 30 keV. Branching ratios for the decays to ⁸Be(0) + α; ¹¹B*(0, 2.12, 4.45, 5.02, 6.74 + 6.79) + p; and ¹⁰B(0) + d are, respectively, 10.5 ± 3.0, 3.0 ± 2.2, 8.0 ± 2.3, 0 ± 3.3, 8.4 ± 3.2, 8 ± 5, and 2.8 ± 2.0% (1979FR04).

81. (a) ¹⁴C(¹⁶O, ¹⁸O)¹²C Q_m = -0.9341
(b) ¹⁴C(¹⁸O, ²⁰O)¹²C Q_m = -1.562

Angular distributions leading to the ground states in reaction (a) have been measured at E(¹⁶O) = 20, 25 and 30 MeV (1973SC24, 1975SC35) and 32 MeV (1968GO01: see (1975SC35)). For reaction (b) see (1972EY01). See also (1978KA23; theor.).

82. ¹⁴N(γ, np)¹²C Q_m = -12.4970

See ¹³C, ¹⁴N in (1976AJ04) and (1979ME1E; theor.).

83. (a) ¹⁴N(n, t)¹²C Q_m = -4.0151
(b) ¹⁴N(n, t)⁴He⁴He⁴He Q_m = -11.2899

Angular distributions of the t₀ group have been measured at E_n = 14 - 15 MeV: see (1968AJ02). At E_n = 18.2 MeV reaction (b) takes place predominantly via sequential decay processes involving ¹²C*(9.6, 10.8, 11.8) (1976TU04). See also ¹⁵N in (1981AJ01).

84. ¹⁴N(p, pd)¹²C Q_m = -10.2724

See (1971WE05). See also (1976DO12; theor.).

85. ¹⁴N(p, ³He)¹²C Q_m = -4.7788

Angular distributions have been studied at E_p = 7.53 to 44.6 MeV [see (1975AJ02)], at 50 MeV (1970SC02: to g.s., 4.4, 12.7, 14.1, 15.1, 16.1) and at 51.9 MeV (1976YO03: to 15.1, 16.1). The results of (1970SC02) strongly indicate J^π = 4⁺ for ¹²C*(14.1). At the highest energy (1976YO03) have measured the angular distributions to the first two T = 1 states in ¹²C and to the analog states in ¹²N, in the (p, t) reaction. See also ¹⁵O in (1981AJ01).

86. (a) ¹⁴N(d, α)¹²C Q_m = 13.5743
(b) ¹⁴N(d, 2α)⁸Be Q_m = 6.2076

Observed α-particle groups are shown in Table 12.19 (in PDF or PS). Angular distributions have been measured at energies up to 28.5 MeV [see (1968AJ02, 1975AJ02)] and at E_d = 2.70 to 2.76 MeV (1977KO33: α₀, α₁, α₂), 15 MeV (1976LU1A: α₀, α₁, α₂) and 40 MeV (1976VA07: α₀, α₁ and α to ¹²C*(12.71, 14.08, 19.5, 20.6, 22.5)). Analysis of the angular distributions with a one-step, ZRDWBA, leads to J^π = (1, 2, 3)⁺, (2, 3)⁺ and (2, 3)⁺, respectively for ¹²C*(19.5, 20.6, 22.5) (1976VA07: spectroscopic factors calculated for all observed transitions). For a comparison of the relative strengths of ¹²C*(12.7, 15.1) at E_d = 40 MeV see (1974VA15). See also reactions 21, 22, 44, 50, 73 and 74. For reaction (b) see (1972FA07). See also ¹⁶O in (1977AJ02), (1975OL1A; applications) and (1978BE1H).

87. ¹⁴N(³He, pα)¹²C Q_m = 8.0808

See ¹⁶O in (1977AJ02).

88. (a) ¹⁴N(α, ⁶Li)¹²C Q_m = -8.7989
(b) ¹⁴N(α, αd)¹²C Q_m = -10.2724

At E_α = 42 MeV angular distributions of ⁶Li ions corresponding to transitions to ¹²C*(0, 4.4) have been measured by (1964ZA1A). For reaction (b) see ¹⁶O in (1977AJ02).

89. ¹⁴N(¹⁰B, 3α)¹²C Q_m = 7.6403

See (1965SH1A).

90. ¹⁵N(γ, t)¹²C Q_m = -14.8484

See (1976PA22). See also (1977SP06) and ¹⁵N in (1981AJ01).

91. ¹⁵N(p, α)¹²C Q_m = 4.9656

Angular distributions of α₀ and α₁ have been measured for E_p up to 18 MeV [see (1968AJ02)], at E_p = 2.99 to 5.14 MeV (1977JA11) and at six energies in the range E_p = 19.85 to 43.35 MeV (1971GU23). At E_p = 43.7 MeV the angular distributions to the 0⁺ states ¹²C*(0, 7.65, 17.76) are fitted by L = 1, and L = 3 is consistent with the distributions to ¹²C*(14.1, 16.1) [J^π = 4⁺ and 2⁺, respectively] (1972MA21). The lifetime of ¹²C*(4.4) τ_m = 65 ± 9 fsec (1970CO09). The energy of the second excited state of ¹²C is 7654.2 ± 1.6 keV. The weighted average of this and previous values leads to E_x = 7654.6 ± 1.1 keV, a value which leads to a sharply reduced rate for the (ααα) process (1973MC01). See also (1966YO1A), (1977RO1H; astrophys.), (1975KU1L; theor.) and (1979ZY02) in ¹⁶O in (1982AJ01).

92. ¹⁵N(α, ⁷Li)¹²C Q_m = -12.3817

At E_α = 42 MeV angular distributions have been obtained for all four of the transitions: ¹²C_g.s. + ⁷Li*(g.s., 0.48) and ¹²C*_4.4 + ⁷Li*(g.s., 0.48) (1968MI05).

93. (a) ¹⁶O(γ, α)¹²C Q_m = -7.1620
(b) ¹⁶O(γ, 3α)⁴He Q_m = -14.4368

See (1975AJ02) and (1975SK06) in ¹⁶O (1977AJ02).

94. (a) ¹⁶O(n, nα)¹²C Q_m = -7.1620
(b) ¹⁶O(p, pα)¹²C Q_m = -7.1620

For reaction (a) see (1968AJ02). Reaction (b) appears to proceed primarily via excited states of ¹³N and ¹⁶O to ¹²C*(4.4): see (1971EP03: E_p = 46.8 MeV) and (1972BO71: E_p = 50 MeV). See also (1975AJ02) for unpublished measurements and (1976GO1E; theor.).

95. ¹⁶O(d, ⁶Li)¹²C Q_m = -5.6885

Angular distributions have been measured at E_d = 12.7, 13.6 and 14.6 MeV (1974GA30, 1975GO09; g.s.), E_d-bar = 16 MeV (1976JA1G; g.s.), E_d = 35 MeV (1975BE01, 1976NA19; g.s., 4.4), 50, 65 and 80 MeV (1978BE1T: g.s., 4.4, 14.1: ZRDWBA) and 80 MeV (1978OE02; to g.s., 4.4, 7.7, 9.6, 14.1, and broad (or unresolved) structures at 14.1 ± 2.6, 19.5 ± 1.5 MeV: ZRDWBA and FRDWBA). (1978BE1T, 1978OE02) report relative S_α. The relative S_α are strongly influenced by the choice of bound state parameters: see (1978BE1T), and compare with (1978OE02). Earlier studies at E_d = 14.6, 19.5, 28 and 55 MeV are listed in (1975AJ02). See also (1973FO1A, 1978BE1H), (1977KU1H, 1978TA1F; theor.) and ¹⁸F in (1978AJ03).

96. ¹⁶O(³He, ⁷Be)¹²C Q_m = -5.5758

Angular distributions have been studied at E(³He) = 25.5 MeV (D. Pisano, Yale Ph.D. thesis [P.D. Parker, private communication]: ¹²C*(0, 4.4) + ⁷Be*(0, 0.4)), 30 MeV (1970DE12: (¹²C*(0, 4.4, 9.6) + ⁷Be*(0, 0.4), ¹²C*(7.7) + ⁷Be_g.s.) and at 70 MeV (1976ST11: ¹²C*(0, 4.4) and ⁷Be*(0, 4.4); S_α are calculated). In the latter experiment ¹²C*(7.7, 9.6) are observed but they are weakly populated (1976ST11). (1975AU01) report the extraction of S_α, the α-particle pickup spectroscopic factor, using a FRDWBA analysis [E(³He) = 26 MeV]. See also (1975AJ02).

97. (a) ¹⁶O(α, 2α)¹²C Q_m = -7.1620
(b) ¹⁶O(α, ⁸Be)¹²C Q_m = -7.2538

At E_α = 90 MeV angular distributions involving ¹²C*(0, 4.4) (reaction (a)) have been analyzed by PWIA and DWBA by (1976SH02): S_α = 2.9 ± 0.5 and 0.70 ± 0.23, respectively. At E_α = 65 MeV angular distributions involving ⁸Be_g.s. (reaction (b)) and ¹²C*(0, 4.4, 7.7, 9.6, 14.1) have been measured by (1974WO1C, 1976WO11) [the ground state distributions have also been studied for E_α = 55 to 72.5 MeV]: S_α = 0.25, 1.07, 0.05, 1.40 for ¹²C*(0, 4.4, 7.7, 14.1). See also (1975AJ02) for earlier work, (1975HA1P, 1975IG1A, 1979BEZV) and (1977CH02; theor.).

98. ¹⁶O(¹³C, ¹⁷O)¹²C Q_m = -0.8021

See (1975SE03) and ¹⁷O in (1977AJ02). See also (1973BR1C).

99. ¹⁶O(¹⁴N, ¹⁸F)¹²C Q_m = -2.7461

See (1966GA10, 1977VO08).

100. (a) ¹⁶O(¹⁶O, ²⁰Ne)¹²C Q_m = -2.4310
(b) ¹⁶O(¹⁷O, ²¹Ne)¹²C Q_m = 0.186
(c) ¹⁶O(¹⁸O, ²²Ne)¹²C Q_m = 2.5061

Angular distributions have been measured at E(¹⁶O) = 23.9 MeV (1974SP06: g.s. + g.s.) and 51.5 MeV (1974RO04: ¹²C*(0, 4.4) and various ²⁰Ne states). At E_c.m. = 17.5 MeV (reaction (a)) and 17 MeV (reactions (b) and (c)) angular distributions involving ¹²C_g.s. (reaction (a)), ¹²C_g.s. and ¹²C*(0, 4.4) (reactions (b) and (c)) as well as a number of states in ²⁰Ne, ²¹Ne and ²²Ne have been studied by (1977KA26). See reaction 25 in ²⁰Ne (1978AJ03) for additional work. See also (1978BO1R; theor.).