(See Energy Level Diagrams for 11C)
Cluster and collective model: (1972LE1L).
Special reactions: (1968BE1F, 1968HA1C, 1968MO1C, 1968NO07, 1969GA18, 1969HI1A, 1969YI1A, 1970KR1C, 1970MO38, 1971AR02, 1971BA16, 1971BI22, 1971EP02, 1973CO1V, 1973JO07, 1973LA19, 1973PH1B, 1973SK01, 1973VA12, 1973WE1N, 1974DI16, 1974HA61).
Applied topics: (1974PE04).
Pion capture and pion reactions: (1968DA1G, 1968NY1A, 1970LI1H, 1971BL02, 1971KA62, 1971NO08, 1972SE13, 1973AL1D, 1973AL1E, 1973AR1B, 1973CH20, 1973HO43, 1973JA1J (and a correlation (1974JA29)), 1974AM01, 1974MI11).
μ = ± 0.997 nm (1968SC18);
Q = ± 0.0322 b (1968SC18).
The half-life of 11C is 20.40 ± 0.04 min (1969AW02). [The weighted mean value of previously reported half-lives is 20.34 ± 0.04 min: see Table 11.15 (in PDF or PS) in (1968AJ02).] log ft = 3.591 ± 0.002 (B. Zimmerman, private communication). Relativistic corrections to the log ft value are considered by (1970ST04). The ratio of K-capture to positron emission is (0.230+0.014-0.011)% (1967CA09). See also (1957SC29, 1969BE09, 1970BE66, 1972CH1G, 1973HO43), (1968FI02) and (1969LE1D, 1969SU15, 1970DA21, 1970KO41, 1971VA1C, 1973EM1B, 1973MU1D, 1973WI04, 1973WI11, 1974LE1G, 1974ME19, 1974WI1M; 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*(8.43) [and a 8.43 MeV γ-ray] are reported. 11C*(8.10) was not observed (1967BA53). See also (1969GU1D). 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 10 MeV: see (1968AJ02) for the earlier references and (1969DE1F, 1971DE2C: E(3He) = 4.0 MeV), (1969HO1F: 4.25 and 6.2 MeV), (1974FU11: 10.5 and 13.0 MeV). 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, 8.43) 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 11.21 (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+ and 3/2+, respectively 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.
A broad resonance is reported at Ep = 1.15 MeV: see Table 11.23 (in PDF or PS) (1956CH20, 1957HU79, 1967PA19). 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). See also (1961DO03).
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 (1973SU1E) and (1973HA1X, 1973SP02; theor.). The lifetimes of 11C*(4.32, 6.49), τm < 20 fsec (1969ROZT; abstract).
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 (1973ZW1A; theor.) and 10C in (1974AJ01).
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 Tables 11.23 (in PDF or PS) and 11.24 (in PDF or PS) (1960OV1A, 1962OV02: Ep = 0.15 to 3.0 MeV). The elastic scattering has also been studied recently by (1970BO17: Ep = 3 to 10.5 MeV), and (1969WA11: Ep = 5.0 to 13.4 MeV; optical model analyses). (1969WA11) report a single broad resonance at Ep ≈ 5 MeV, while (1970BO17) report seven resonances in the corresponding energy interval, in addition to resonances at Ep = 3.6 and 4.4 MeV. See also (1962AN11). The depolarization parameter D has been measured for polarized protons with Ep = 25 MeV (1974BI1F) and 50 MeV (1970BA05). See also (1970BE1B) and (1973ZW1A, 1974GU13; theor.).
The yield of γ1 [from 10B*(0.72)] rises monotonically from Ep = 1.5 to 4.1 MeV (1952DA05, 1954DA20, 1957HU79, 1964BE31) and then shows resonance behavior at Ep = 4.35 and 5.73 MeV (1962OP03: see Table 11.23 (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) with 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 11.22 (in PDF or PS)]: these do not occur in the yield of p1 and p3 (1971WA21).
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 (1974AJ01).
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 parameters of observed resonances are displayed in Tables 11.23 (in PDF or PS) and 11.24 (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 (see (1962OV02, 1964JE01) and (1959AJ76)). Alpha particles to the 0.43 MeV 7Be state (α1) and 0.43 MeV γ-rays exhibit all but the 1.2 MeV resonance (see (1962OP03, 1964BE31, 1964JE01, 1966SE03) and (1959AJ76)). Weak resonances are also reported at 2.32, 2.57 and 3.59 MeV (1964BE31). A broad maximum dominates the region from Ep = 4 MeV to about 7.5 MeV (1966SE03). See also (1968HA1B), (1973ZW1A; theor.) and (1974PE1C; applied).
Angular distribution measurements have recently been reported at Ed = 0.5 to 0.8 MeV (1969CH04: n to 11C*(6.35 + 6.49)), 5.8 MeV (1970BO34: see Table 11.25 (in PDF or PS)) and 11.8 MeV (1971MU18: n0). See also (1969JO1F). For recent angular correlation measurements see (1972TH14, 1973PA1N). A great deal of work had previously been done on this reaction: see (1959AJ76, 1968AJ02 [particularly Table 11.20 (in PDF or PS)]) for a discussion of the earlier work. Information on the γ-decay of 11C states has been summarized by (1965OL03) and is incorporated in Table 11.21 (in PDF or PS).
Angular distributions have been measured recently at E(3He) = 1.38 MeV (1970BE1F: d0), 11.0 MeV (1970BO34: see Table 11.25 (in PDF or PS)), 18.0 MeV (1973FO02: deuterons to 11C*(8.66, 8.70)) and 21.0 MeV (1970FO05, 1971CO07: see Table 11.25 (in PDF or PS)). Table 11.25 (in PDF or PS) displays also the spectroscopic factors 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, 9.28) 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).
Angular distributions of 6He ions corresponding to the transition to 11Cg.s. have been measured at E(7Li) = 3.0, 3.5 and 3.8 MeV (1968ST12). At E(7Li) = 24 MeV, the population of 11C*(0, 2.00, 4.32, 4.80, 6.34 + 6.48, 6.90, 7.50, 8.10, 8.43, 8.66) is reported (1974KO1G).
Neutron groups have been observed to 11C*(0, 2.008, 4.320, 4.806, 6.330, 6.481) (± 20 keV) (1965OV01). See also (1970CL01). Angular distributions of the n0 group have been measured at many energies up to Ep = 18.5 MeV [see (1968AJ02)] and at 30.5 and 49.5 MeV (1970CL01: also n1 and n2 + n3). See also (1969MO32, 1973GO1V), (1969BA1N; astrophys. considerations) and 12C.
Angular distributions of t0 and t1 have been measured at E(3He) = 10 MeV (1967CR04) and 14 MeV (1970NU02). See also (1969OP1A, 1970OP1B). 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 11.22 (in PDF or PS)] and, possibly, 14.15 MeV (1971WA21). See also (1968BR23).
At E(6Li) = 30 MeV, 6He groups are observed corresponding to 11C*(0, 2.00, 4.32, 4.80, 6.48, 6.90) and the angular distribution to 11Cg.s. is reported (1972LE1P).
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 the discussion in (1973DI1C, 1973SP03). See also (1969DE12, 1973GL1C, 1974SC23), (1970MU1D, 1971BI01, 1973MS01, 1973MS02; theor.) and 12C.
For reaction (a) see (1969BA1F; theor.) and 12C. For reaction (b) see (1973HO43). See also (1970LI1H) and the "Pion capture and pion reactions" section in 12C. For reaction (c) see 13C. For reaction (d) see (1968DE22, 1968PA05, 1969PO01) and 12C.
Angular distributions have been recently measured at Ep = 55 MeV (1974SH1N: d0, d1, d2+3), 100 MeV (1968LE01, 1969LI01: d0, d1, d2+3, d4+5+6), 155.6 MeV (1969BA05: d to 11C*(0, 2.0, 4.3, 4.8, 6.7, 8.0, 11.0)), 185 MeV (1971KA56: see Table 11.26 (in PDF or PS)) and 700 MeV (1973TH1A, 1974BA58: d0 → d4, d6). The broad peak at Ex = 15 ± 0.7 MeV and the weak [≈ 7 MeV broad] structure at Ex = 18 - 23 MeV reported by (1969BA05) are not observed by (1971KA56). See also (1969SU02, 1973FA10). For a listing of earlier angular distribution measurements [Ep = 19 to 60 MeV] see (1968AJ02). See also (1968TI1A, 1972RO1K, 1974KI1A) and (1968JA1D, 1969DO08, 1969TO1A, 1970BA1N, 1971LO28 [pion], 1971MC15, 1972ST33, 1973TA27, 1974IN07; theor.).
At Ed = 28 MeV the t0 angular distribution has been measured and a detailed comparison has been made with the results from the mirror reaction 12C(d, 3He)11B (1966DE1C, 1968GA13). Angular distributions of the t0 group have also been measured at Ed = 20.0, 24.0 and 28.0 MeV by (1971IN1C; unpublished thesis): at the highest energy angular distributions of several triton groups to excited states of 11C are also reported. See also (1971BO50; theor.) and (1968AJ02).
Angular distributions have been measured at many energies. Recent experiments are reported at E(3He) = 9.5, 10.5 and 11.5 MeV (1970BO34), 13.9 MeV (1968OB01: α0 → α3), 16, 17 and 18 MeV (1970GR08), 19.1, 27.1 and 35.7 MeV (1968AR12), 24 and 28 MeV (1973FU02), 24.0, 29.2, 34.7 and 39.6 MeV (1974YA10: α0, α1, α2), 35.6 MeV (1970FO05: α0 and α to 11C*(8.10, 8.43)), 42 MeV (1973SI11: α0 → α4), 44.8 MeV (1966BA13: α0) and 217 MeV (1974GE09: α0, α1, α2, α3). See Table 11.27 (in PDF or PS) for a display of the results and (1968AJ02) for a summary of the extensive earlier work. For discussions of the reaction mechanisms see, e.g. (1970BO34, 1973FU02).
Alpha-γ correlations have been studied for E(3He) = 4.7 to 12 MeV: see, in particular, (1968EA03). Their results are summarized in Table 11.21 (in PDF or PS) and are discussed in detail in reaction 22 (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 (1970CA28, 1970JA1E), (1969DO08, 1972WE1F, 1974DO15; theor.) and 15O in (1976AJ04).
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).
Reaction (a) has been observed at E(10B) = 100 MeV: 11Cg.s. is much more strongly populated than 11C*(2.00) (1973YO1C, 1973YO1D). See also reaction 58 in 11B (1974HA1V). The angular distribution involving the ground state transitions has been measured for reaction (b) at E(12C) = 114 MeV (1974AN36).
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 11.22 (in PDF or PS)] whose Jπ is determined to be 1/2- [it is thus the mirror of 11Be*(0.32)] (1968CO26, 1968FL02). 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 (1969SC1F) and (1971KA04; theor.).
Angular distributions have been reported at Ep = 4.99 to 5.55 MeV (1969WE02: α0), 6.0 to 9.0 MeV (1968SH11: α0) and 7.53, 8.03, 9.54 and 10.54 MeV (1970ME30: α0, α1) and 20.5 to 44.3 MeV (1974PI05: α0, α1). See also (1972MA21), (1968AJ02) and 15O in (1976AJ04).
At Eα = 42 MeV, the angular distribution involving the transition to 9Beg.s. + 11Cg.s. has been measured (1972RU03).