(See Energy Level Diagrams for 11C)
Special levels: (1976IR1B).
Pion capture and reactions (See also reactions 25 and 26.): (1975BA66, 1975BH03, 1975HU13, 1975KA1G, 1975PA1D, 1975SC1N, 1975SI18, 1975ZI1B, 1976MI15, 1977BA2H, 1977LE1G, 1977MA1M, 1978AM01, 1978HI03, 1978MO01, 1978WA1B, 1979AN1J, 1979HU02).
Q = 34.26 mb (1978LEZA).
The half-life of 11C is 1223.1 ± 1.2 sec [mean of previously reported values (see (1975AJ02)); mainly based on τ1/2 = 1222.9 ± 1.2 sec (1975AZ01)]. See also (1975BE28). Log ft = 3.599 ± 0.002 (1975AZ01) based on Eβ+(max) = 960 ± 1 keV (from Qm). See also (1975AZ01). (1975BE28) measure Eβ+(max) = 960.8 ± 2.6 keV. The ratio of K-capture to positron emission is (0.230+0.014-0.011)% (1967CA09). See also (1975AJ02, 1977BA48, 1978RA2A) and (1975KR14, 1975WI1E, 1976BE1E, 1976DO1G, 1977RI08, 1977YO1D, 1977YO1E, 1979DE15; theor.).
At E(6Li) = 4.1 MeV [reaction (a)] 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, n-γ coincidences via 11C*(8.42) [and a 8.42 MeV γ-ray] are reported. 11C*(8.10) was not observed (1976BA53). The lifetimes, τm, for 11C*(4.32, 6.90, 7.50) are < 140, < 69 and < 91 fsec, respectively. The upper limits for τm of 11C*(6.34, 6.48) [which were unresolved] are 0.5 psec. The ground state transition from 11C*(7.50) has Eγ = 7505 ± 8 keV (1969TH01). For reaction (b) see (1968AJ02). For reaction (c) see (1974CE06).
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 (1975AJ02) and (1979OS10). The dominant L-values from the angular distributions reported by (1974FU11) 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 by (1971WA21) [Ex = 12.17 ± 0.05 and 12.55 ± 0.05 MeV] and by (1969BR30) [Ex = 12.5 ± 0.1, 13.7 ± 0.1 and 14.7 ± 0.1 MeV]: see Table 11.22 (in PDF or PS).
Gamma branching ratios and multipolarities for 11C levels up to Ex = 7.5 MeV have been studied by (1965OL03, 1965RO07): see Table 11.20 (in PDF or PS). Together with evidence from reactions 12 and 27 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, 1965RO07) and reaction 3 in (1968AJ02) for a summary of the evidence concerning these assignments. See also (1977ZA1B; applied), (1977OS08; theor.) and 12C.
The thick target yield for this reaction has been measured for Ep = 0.27 to 3.0 MeV (1975PE1A): see also reaction 11. A broad resonance is reported at Ep = 1.15 MeV: see Table 11.22 (in PDF or PS). Capture γ-rays are observed corresponding to the ground state transition and to cascades via 11C*(2.00, 4.32, 6.48): see Table 11.21 (in PDF or PS) (1961JA11). 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 (1974LO1B, 1975AJ02), (1976RO1Q; astrophys.) and (1977YO1F; 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 11.23 (in PDF or PS)) (1963EA01). 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 (1966SE03). See also 10C in (1979AJ01).
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 11.22 (in PDF or PS) (1962OV02: Ep = 0.15 to 3.0 MeV). At higher energies (to Ep = 10.5 MeV) a single broad resonance is reported at Ep ≈ 5 MeV (1969WA11) while (1970BO17) suggest additional structure. 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 MeV (1976BI1E) and 50 MeV (1970BA05). See also (1977SA1B) and (1975BL10; theor.).
The yield 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 (1962OP03: see Table 11.22 (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 (1966SE03). [The cross section below Ep = 10 MeV appears to be in error: see (1969WA23).] Yields of five other γ-rays involved in the decay of 10B*(1.74, 2.16, 3.59, 5.18) have also been measured by (1966SE03) in the range Ep = 4 to 12 MeV.
Yield curves for inelastically scattered protons have 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 (1969WA23). It had previously been suggested by (1966SE03) that the formation of T = 1 states was relatively suppressed in this reaction. (1969WA23) find that the isotopic spin effect disappears when a correction factor (2Jf+1) is included. 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 and 12.50 MeV [see Table 11.21 (in PDF or PS)]: these do not occur in the yield of p1 and p3 (1971WA21). See also (1976DE15), 10B in (1979AJ01) and (1975AJ02).
The ground-state yield shows slight maxima at energies similar to those in the (p, α) yield in the range Ep = 4 to 10 MeV. However, the angular distributions do not vary strongly over the region and it is suggested that a direct interaction mechanism dominates (1963JE01). (1966SE03) report two strong maxima at Ep ≈ 4.5 and 6.5 MeV. See also 8Be in (1979AJ01).
The total cross section for this reaction has been measured for Ep = 60 to 180 keV by (1972SZ02): 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 used as fuel in CTR devices.
The parameters of observed resonances are displayed in Table 11.22 (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 (1966SE03). For spallation studies see (1976BO08, 1977AV01). See also (1976GRZR, 1976IN04) and (1976RO1Q; astrophys.).
Table 11.23 (in PDF or PS) presents the results obtained in this reaction and in the (3He, d) reaction (1955MA76, 1963OV02, 1970BO34). Information on the γ-decay of 11C states has been summarized by (1965OL03) and is incorporated in Table 11.20 (in PDF or PS). For the earlier work see (1959AJ76, 1968AJ02 [particularly Table 11.20 (in PDF or PS)], 1975AJ02). See also (1972RE1C) and (1974LO1B).
Table 11.23 (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) (1973FO02). Singlet deuteron emission has been studied at E(3He) = 8, 10 and 11 MeV by (1970BO07). For the earlier work see (1975AJ02).
Angular distributions of 6He ions have been measured at E(7Li) = 3.0 to 3.8 MeV (1968ST12; to 11Cg.s.) and at 24 MeV (1977KO27: to 11C*(0, 4.32, 6.48)). 11C*(2.0, 4.80, 8.42, 8.66 + 8.70) are also populated (1977KO27).
Yields of 11C have been measured from threshold to Eγ = 169 MeV (1976MI15; see it also for other references).
Neutron groups have been observed to 11C*(0, 2.008, 4.320, 4.806, 6.330, 6.481) (± 20 keV) (1965OV01; Ep = 10.9 MeV). Angular distributions of the n0 group have been measured at many energies up to 49.5 MeV [see (1975AJ02)] and at Ep = 3.15 to 4.85 MeV (1978VA12). See also (1977ME1C) and 12C.
Angular distributions of t0 and t1 have been measured at E(3He) = 10 MeV (1967CR04), 14 MeV (1970NU02) and 217 MeV (1976WI05; also to 11C*(4.3, 4.8, 6.48, 8.10)). The latter have been compared with microscopic calculations and calculations of two-step processes (1976WI05). At E(3He) = 26 MeV the known states of 11C below Ex = 11 MeV are populated and triton groups are also observed to states, assumed to be T = 3/2, at Ex = 12.15, 12.57 and 13.92 MeV [see Table 11.21 (in PDF or PS)] and, possibly, 14.15 MeV (1971WA21).
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 (1975SC05, 1979KI1H). For the (e, n) reaction see (1978KL03).
For reaction (a) see (1977KN04, 1978SH14). (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 (1973HO43, 1979LI11) for reactions (b), reaction 54 in 11B and the "GENERAL" section here. For reaction (c) see 13C in (1981AJ01). For reaction (d) see (1976MCZP). See also (1975AJ02) and 12C.
At Eπ+ = 49.3 MeV angular distributions have been obtained to 11C*(0, 2.0 ± 0.2, 4.35 ± 0.2, 6.4 ± 0.2, 8.5 ± 0.2, 12.5 ± 0.3). At the same momentum transfer this reaction and the (p, d) reaction give similar intensities to the low-lying energy states of 11C (1978AM01). See also (1979AN1K, 1979AN1M).
Angular distributions have been measured for Ep = 19 to 700 MeV [see (1968AJ02, 1975AJ02)] and recently at 65 MeV (1975RO27; see Table 11.24 (in PDF or PS)), 121.2 MeV (1976ANZP) and 650 and 800 MeV (1978IG1A, 1978WH1A, 1979BO1A). Observed states of 11C are displayed in Table 11.24 (in PDF or PS). See also (1975AJ02, 1975BE1Q, 1975IG1A, 1977HA1P, 1977MO1F, 1978AZ02, 1978IG1B, 1978SH1F, 1979WH1A), (1977HA1N [in 13N, (1981AJ01)], and (1975GE1H, 1975RO29, 1976GR1G, 1976SHZQ, 1976WA15, 1977KA07, 1977LU1A, 1978CO1J, 1978LU1B;; 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 (1968GA13, 1966DE1C). At Ed-bar = 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 (1978CO13). See also 14N in (1981AJ01), and (1975AJ02).
Angular distributions have been measured at many energies to E(3He) = 217 MeV [see (1968AJ02, 1975AJ02) for the earlier results] and at 11.0 MeV (1978CU02: α0, α1), 18, 20 and 22 MeV (1977AD07: α0, α1), at E(pol. 3He) = 33 MeV (1976KA23: α0, α1), and at E(3He) = 35.6 MeV (1978FO13: see Table 11.25 (in PDF or PS)), 82.1 MeV (1976TA12: α0, α1, α2+3, α4+5) and at 217 MeV (1978VA05: α0, α1). See also (1976STYX: 60 MeV) and (1978CH1P: 132 MeV). At E(3He) ≈ 217 MeV (1975GE16, 1978VA05) also report the population of unresolved low-lying states, as well as the excitation of states with Ex = 11.2, 12.4, 15.3, 23 and (28) MeV. See Table 11.25 (in PDF or PS) for a display of the results.
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-γ 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). See also (1976RO1L, 1977MO1F) and 15O in (1981AJ01).
At E(6Li) = 36 MeV the angular distributions involving 7Lig.s.+11Cg.s. and 7Li*0.48 + 11C*2.00 have been studied by (1973SC26).
At E(10B) = 100 MeV, angular distributions have been measured involving 11Bg.s. + 11Cg.s., 11Bg.s. + 11C2.00 and (11Cg.s. + 11B2.12) + (11Bg.s. + 11C2.00) [unresolved], as well as unresolved groups involving the first few states of 11B and 11C (1975NA15, 1975VO05, 1976NA09). See also (1975AJ02).
At Ep = 43.7 to 50.5 MeV (1968CO26, 1968FL02) and at Ep-bar = 49.6 MeV (1974MA12) 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 11.21 (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 (1968CO26). Angular distributions have also been measured for Ep = 26.9 to 43.1 MeV (1975MI01: t0 → t3). 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 22 is not observed by (1974BE20). See also 14N in (1981AJ01).
Angular distributions have been reported at a number of energies in the range Ep = 5.00 to 44.3 MeV for the α0 and α1 groups: see (1975AJ02) for the earlier work and (1974HU02: 9.0 to 12.0 MeV; α0). See also 15O in (1981AJ01), (1976IN01; astrophys.), (1975CH1H; applied) and (1975KU1L; theor.).
At Ed = 80 MeV angular distributions involving 11C*(0, 2.0, 4.3 + 4.8, 6.3 + 6.5 + 6.9) have been measured (1978OE1A).
At Eα = 42 MeV, the angular distribution involving the two ground state transitions has been measured (1972RU03).