(See Energy Level Diagrams for 11C)
Q = 34.26 mb (1978LEZA).
The half-life of 11C is 1223.1 ± 1.2 sec (This value may not be correct, see Erratum to this publication). Log ft = 3.599 ± 0.002. The ratio of K-capture to positron emission is (0.230+0.014-0.011)%. See (1980AJ01) for references. See also (1980RA16), (1984BO1C; astrophys.), (1982KA1C; applied) and (1980AF1A; theor.).
At E(6Li) = 4.1 MeV angular distributions have been obtained for the neutrons to 11C*(2.00, 4.32, 4.80, 6.34 + 6.48, 6.90, 7.50). In addition, nγ coincidences via 11C*(8.42) [and an 8.42 MeV γ-ray] are reported. 11C*(8.10) was not observed. The lifetimes, τm, for 11C*(4.32, 6.90, 7.50) are < 140, < 69 and < 91 fsec, respectively. See (1980AJ01) for references.
At the resonances at Eα = 0.884 ± 0.008 and 1.376 ± 0.003 MeV [11C*(8.107, 8.420)] ωγ = 0.331 ± 0.041 and 3.80 ± 0.57 eV, Γγ = 0.350 ± 0.056 and 3.1 ± 1.3 eV for these two states and Γα = 6+12-2 and 12.6 ± 3.8 eV, respectively (1984HA13).
Reported neutron groups are listed in Table 11.16 (in PDF or PS) of (1968AJ02). Angular distributions have been studied in the range E(3He) = 1.3 to 13 MeV: see (1980AJ01). The dominant L-values are 0 for 11C*(0, 8.10), 1 for 11C*(6.34, 7.50), 2 for 11C*(2.00, 4.32, 4.80, 6.48, 8.42) and 3 for 11C*(6.90). Neutron groups to T = 3/2 states have been reported at Ex = 12.17 ± 0.05 [see, however, reaction 30], 12.55 ± 0.05 MeV and 14.7 ± 0.1 MeV: see Table 11.19 (in PDF or PS).
Gamma branching ratios and multipolarities for 11C levels up to Ex = 7.5 MeV have been studied by (1965OL03): see Table 11.18 (in PDF or PS). Together with evidence from reactions 12 and 23 they lead to assignments of Jπ = 1/2-, 5/2-, 3/2-, 1/2+, 7/2-, 5/2+, 3/2+ for 11C*(2.00, 4.32, 4.80, 6.34, 6.48, 6.90, 7.50): see (1965OL03) and reaction 3 in (1968AJ02) for a summary of the evidence concerning these assignments. See (1980AJ01) for references. See also 12C, (1981AN16, 1982MCZZ), (1979WA1F; applied) and (1981OS1H).
This reaction has been investigated for Ep = 0.07 to 17.0 MeV. Reported resonances are displayed in Table 11.20 (in PDF or PS). Observed capture γ-rays are displayed in Table 11.18 (in PDF or PS) [see also for τm measurements]. Capture measurements for Ep = 0.07 to 2.20 MeV are consistent with five new resonances (see Tables 11.20 (in PDF or PS) and 11.18 (in PDF or PS)), the lowest two (at Ep = 10 and 560 keV) of which are s-wave resonances. Thermonuclear reaction rates for T = (0.01 → 5) × 109 °K are deduced from the results (1983WI09; see also for spectroscopic factors).
The 90° yield of γ0 has been measured for Ep = 2.6 to 17 MeV and angular distributions have been obtained for Ep = 2.8 to 14 MeV. The excitation function is consistent with the giant resonance centered at Ex ≈ 16 MeV. In addition to weak structures at Ep = 4.75 MeV and 10.5 MeV, there are three major peaks at Ep = 4.1, 7.0 and 8.8 MeV (Γ = 1 - 2 MeV) [Ex = 12.4, 15.0, 16.7 MeV]. At 11C*(12.4), the γ0 angular distribution is essentially isotropic: ΓpΓγ/Γ ≈ 200 eV, Γγ ≈ 5 keV (assuming Γp ≈ 10 keV). The Ep = 4.1 MeV resonance is probably part of the E1 giant resonance and is formed by s-wave capture. At the two higher resonances the angular distributions are characteristic of E1 giant resonances in light nuclei. The 10B(p, γ1) cross section is small for Ep = 2.6 to 17 MeV (1970KU09). See also (1979RO12; applied).
The total (p, n) cross section has been measured to Ep = 10.6 MeV: broad maxima are observed at Ep = 5.92 ± 0.02, 6.68 ± 0.04, 7.33 ± 0.05 and 7.60 ± 0.05 MeV (see Table 11.20 (in PDF or PS)). The cross section for formation of 10Cg.s. measured up to 12 MeV shows similar behavior to 8 MeV. At Ep ≈ 8 MeV, a sharp maximum is observed. The cross section for production of 3.35 MeV γ-rays (from 10C*) does not appear to show structure for Ep = 8.5 to 12 MeV. For references see (1980AJ01). See also 10C in (1984AJ01) and (1979BA68).
Below Ep = 0.7 MeV the scattering can be explained in terms of pure s-wave potential scattering but the possibility of a state near Ep = 0.27 MeV (Ex = 8.95 MeV) cannot be excluded. The elastic scattering then shows two conspicuous anomalies at Ep = 1.50 ± 0.02 MeV and at 2.18 MeV [Ex = 10.05 and 10.67 MeV] with Jπ = 7/2+ and 9/2+: see Table 11.20 (in PDF or PS). At higher energies (to Ep = 10.5 MeV) a single broad resonance is reported at Ep ≈ 5 MeV. The yield of p0 has also been measured at θ = 150° for Ep = 5.4 to 7.5 MeV (1981HO13). Polarization measurements are reported at 30.3 MeV (1976DE15, 1977PH02): optical-model parameters are derived. The depolarization parameter D has been measured for polarized protons with Ep = 26 and 50 MeV. For references see (1980AJ01).
The yield of γ1 [from 10B*(0.72)] rises monotonically from Ep = 1.5 to 4.1 MeV and then shows resonance behavior at Ep = 4.36 and 5.73 MeV: see Table 11.20 (in PDF or PS). For Ep = 6 to 12 MeV, the cross section for γ1 shows several sharp maxima superposed on a broad maximum (Γ ≈ 2.5 MeV) at Ep ≈ 7.2 MeV. See however (1975AJ02). Yields of five other γ-rays involved in the decay of 10B*(1.74, 2.16, 3.59, 5.18) have also been measured in the range Ep = 4 to 12 MeV [see (1975AJ02)]. The yield of 0.72 MeV γ-rays has been studied for Ep = 2.0 to 4.1 MeV: no resonances are observed (1979RI12).
Excitation curves for the p1, p2 and p3 groups have been measured for Ep = 3.5 to 5.0 MeV. Possible resonances are observed in the p2 yield [to the T = 1 state 10B*(1.74)] corresponding to the first T = 3/2 states at Ex = 12.16 [see, however, reaction 30] and 12.50 MeV [see Table 11.19 (in PDF or PS)]: these do not occur in the yield of p1 and p3. Yield curves for inelastically scattered protons have also been measured at Ep = 5.0 to 16.4 MeV (p1, p2, p3), 6.6 to 16.4 MeV (p4), 8.9 to 16.4 MeV (p5) and 10.9 to 16.4 MeV (p to 10B*(6.03)): the principal feature for all groups, except that to 10B*(6.03), is a structure at Ep ≈ 7.5 MeV, Γ ≈ 4 MeV. In addition narrower structures are observed, including three at Ep = 5.75, 6.90 and 7.80 MeV (± 0.2 MeV) and widths of ≈ 500 keV. For π+ production see (1980DI02, 1981CO1L, 1982LO1K). See also (1979GLZV; theor.) and 10B in (1984AJ01).
Polarization measurements have been carried out at Ep = 49.6 MeV for the deuterons to 9B*(0, 2.36): see (1975AJ02).
The total cross section for this reaction has been measured for Ep = 60 to 180 keV: the extrapolated cross section at the Gamow energy, taken to be 19.1 keV, is ≈ 10-12 b. The thick-target yield for Ep = 75 keV to 3 MeV has been measured by (1975PE1A): the 7Be yield constitutes a potential problem if natural boron is ussed as fuel in CTR devices.
The parameters of observed resonances are displayed in Table 11.20 (in PDF or PS). The ground-state (α0) α-particles exhibit broad resonances at Ep = 1.17, 1.53, 2.18, 3.0, 4.4, 5.1 and 6.3 MeV. Alpha particles to 7Be*(0.43) [α1] and 0.43 MeV γ-rays exhibit all but the 1.2 MeV resonance: see (1975AJ02). A broad maximum dominates the region from Ep = 4 MeV to about 7.5 MeV. A recent study of the yeild of 0.43 MeV γ-rays for Ep = 2.0 to 4.1 MeV suggests that the 3.0 MeV resonance, which is asymmetric, is due to two broad states. A weak structure at Ep = 2.5 MeV is also reported (1979RI12). See also 7Be in (1984AJ01), (1979RA20) for the cross section at Ep = 740 MeV for 7Be production, (1979RO12; applied) and (1983LE28, 1983SZZY; astrophys.).
Table 11.21 (in PDF or PS) presents the results obtained in this reaction and in the (3He, d) reaction. Information on τm and on the γ-decay of 11C states is displayed in Table 11.18 (in PDF or PS): see (1968AJ02, 1975AJ02) for references. See also (1981AN16), (1979LE1D; applied) and 12C.
Table 11.21 (in PDF or PS) displays the information derived from this reaction and from the (d, n) reaction. The study of the angular distributions of the deuterons to 11C*(8.66, 8.70) shows that these levels are the analogs, respectively, of 11B*(9.19, 9.27) whose Jπ are 7/2+ and 5/2+ [the 11B states were studied in the (d, p) reaction]: Γc.m. are ≪ 9 keV and 15 ± 1 keV, respectively, for 11C*(8.66, 8.70): see (1975AJ02) for references.
Angular distributions of 6He ions have been measured at E(7Li) = 3.0 to 3.8 MeV and at 24 MeV [to 11C*(0, 4.32, 6.48)]. 11C*(2.0, 4.80, 8.42, 8.66 + 8.70) are also populated: see (1980AJ01) for references.
Elastic angular distributions have been obtianed at E(14N) = 73.9 and 93.6 MeV (1979MO14).
Angular distributions have been measured at many energies up to 49.5 MeV [see (1980AJ01)] and at 5.49 to 7.29 MeV (1981HO13; n0, n1). 11C*(4.32, 4.81, 6.33, 6.48) are also populated. See also (1981AN16, 1981MU1D), 12C and (1980BA11; theor.).
Angular distributions of t0 and t1 have been measured at E(3He) = 10, 14 and 217 MeV [the latter also for the triton groups to 11C*(4.3, 4.8, 6.48, 8.10) [see (1980AJ01)] and at E(pol. 3He) = 33 MeV (1981BA1G). At E(3He) = 26 MeV the known states of 11C below Ex = 11 MeV are populated and triton groups are also observed to the possibly T = 3/2 states displayed in Table 11.19 (in PDF or PS) as well as a state at 14.15 MeV. For references see (1980AJ01).
The fraction of transitions to the ground and to excited states of 11C [and to 11B states reached in the (γ, p) reaction] has been measured at Ebs = 24.5, 27, 33 and 42 MeV: the ground state is predominantly populated. The population of analog states in the (γ, n) and (γ, p) reactions are similar. And a significant decay strength is found to the positive-parity states with 6 < Ex < 8 MeV. In general the main contribution to the strength of the transitions to the various excited states of 11B, 11C lies in rather localized energy bands in 12C which are a few MeV wide (1970ME17). See also reactions 24 and 25 in (1980AJ01), 12C, (1979KI04, 1980GA29, 1980GO13) and (1982LO08; theor.).
(1978MO01) report the strong population of the 5/2- state 11C*(4.32) (and of the analog state in 11B) for Eπ+ = 60 to 300 MeV. See also (1982BU20) as well as (1982HO1C) and (1980KE13; theor.). For reactions (b) and (c) see (1980AJ01), and (1980MC1E) for reaction (c). See also 12C.
Angular distributions have been obtained to 11C*(0, 2.0, 4.3 + 4.8, 6.5, 8.5) by (1978AM01; Eπ+ = 49.3 MeV) and (1981AN10; Eπ+ = 90 and 180 MeV). At the same momentum transfer this reaction and the (p, d) reaction give similar intensities to the low-lying states of 11C. (1978AM01) have also reported population of a T = 3/2 state at Ex = 12.5 ± 0.3 MeV. However (1981AN10) do not observe it: they suggest the possible excitation of 11C*(13.3). See the discussion in (1982DO01). See also (1980GO16) and (1982LO1B; theor.).
Angular distributions have been measured for Ep = 19 to 800 MeV [see (1968AJ02, 1975AJ02, 1980AJ01) for references] and at Ep = 52 MeV (1980OH06; d to 11C*(0, 4.30, 6.48)) and at Epol. p = 65 MeV (1980HO18; d0, d1). Observed states of 11C are displayed in Table 11.24 (in PDF or PS) of (1980AJ01). See also 13N in (1986AJ01), (1981IR1A), (1980WH1A, 1982LO1B, 1982YA1A, 1983MO1F) and (1980CO06, 1980SA1K, 1980WI02, 1981JA1D, 1981LU1A, 1982SH06, 1983LU01; theor.).
At Ed = 28 MeV the t0 angular distribution has been measured and a detailed comparison has been made with the results for the mirror reaction 12C(d, 3He)11B. At Ed = 29 MeV the t0 angular distribution leads to spectroscopic factors C2S = 2.82 or 3.97 depending on different sets of parameters for 11Cg.s.. 11C*(2.0, 4.32) are also populated. See also 14N in (1986AJ01), and (1980AJ01) for references.
Angular distributions have been measured at many energies to E(3He) = 217 MeV [see (1968AJ02, 1975AJ02, 1980AJ01) for references] as well as at 99.4, 119.1 and 139.6 MeV (1981TA25; α0 → α3, α5). Observed states are displayed in Table 11.22 (in PDF or PS). In addition the excitation of states at Ex = 11.2, 12.4, 15.3, 23 and (28) MeV has also been suggested: see (1980AJ01).
At E(3He) = 35.6 MeV (1978FO13) find good fits by DWBA for strong l = 1 transitions, and reasonable agreement in the forward direction, as well as with Stheor., for weak l = 1 transitions. Transitions involving l = 0 or 2 (and 3) are weak and the agreement with theory is poor. It is suggested that 11C*(8.10) [3/2-] is predominantly a p3/2 hole state coupled to 12C*(7.65) [0+] (1978FO13).
Alpha-gamma correlations have been studied for E(3He) = 4.7 to 12 MeV: see, in particular, (1968EA03). Their results are summarized in Table 11.20 (in PDF or PS) and are discussed in detail in reaction 22 of (1968AJ02). A measurement of the linear polarization of the 2.00 MeV γ-ray (together with knowledge of the τm) fixes Jπ = 1/2- for 11C*(2.00) (1968BL09). τm = 10.3 ± 0.7 fsec for 11C*(2.00) (1981AL1C). See also 12N, 15O in (1981AJ01, 1986AJ01), (1983MO1F) and (1982KU17; theor.).
Reaction (b) has been studied at E(3He) = 75 MeV: transitions to 11C*(0, 2.0, 4.3, 4.8, 6.3) are observed by looking at p, t angular correlations (1983ST10).
The angular distributions involving 7Lig.s. + 11Cg.s. and 7Li*0.48 + 11C*2.00 have been studied at E(6Li) = 36 MeV: see (1980AJ01).
At E(10B) = 100 MeV, angular distributions have been measured involving 11Bg.s. + 11Cg.s., 11Bg.s. + 11C2.00 and 11Cg.s. + 11B2.12. Both 12C(10B, 11B)11C (with 11B detected in the forward direction) and 12C(10B, 11C)11B (with 11C detected in the forward direction) were measured. In each case, 11Bg.s. + 11C2.00 and 11Cg.s. + 11B2.12 were not resolved, but the authors (1975NA15) argue that the (10B, 11B) case would have little contribution from 11Cg.s. + 11B2.12 (because of the spins of 10B and 11B2.12), so that it essentially gives the 11Bg.s. + 11C2.00 angular distribution, and similarly for the other case.
Angular distributions involving 11Cg.s. have been studied at E(12C) = 114 MeV [see (1980AJ01)] and at 93.8 MeV (1979FU04). Cross sections for production of 11C at E(12C) = 0.40, 1.05 and 2.1 GeV/nucleon are reported by (1983SM03). See also (1981CH1R).
At Eπ+ = 32 MeV angular distributions have been obtained for the deuterons to 11C*(0, 6.48) (1982DO01).
At Ep = 43.7 to 50.5 MeV angular distributions of the tritons have been studied to 11C*(0, 2.00, 4.32, 4.80, 6.48, 6.90, 7.50) and to a T = 3/2 state at Ex = 12.47 MeV [see Table 11.19 (in PDF or PS)] whose Jπ is determined to be 1/2- [it is thus the analog of 11Be*(0.32)]. The state decays primarily by p → 10B*(1.74). Alpha decay to 7Be*g.s. + 0.4 is also observed. Angular distributions have also been measured for Ep = 26.9 to 43.1 MeV [see (1980AJ01)] and at Ep = 65 MeV (1982KA01; t0, t1). At Ep = 46.7 MeV the T = 3/2 state is also observed by (1974BE20) who, in addition, report the population of states with Ex = 11.03 ± 0.03, 13.33 ± 0.06, 13.90 ± 0.04 and 14.07 ± 0.04 MeV [Γ = 300 ± 60, 270 ± 80, 150 ± 50 and 135 ± 50 keV, respectively]. However, the T = 3/2 state at Ex = 12.16 MeV reported by (1971WA21) in reactions 4, 8 and 19 is not observed by (1974BE20).
This reaction has been studied at E(10B) = 100 MeV: see (1980AJ01).