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11C (2012KE01)(See ![]() ![]() ![]()
Q = 34.26 mb (1969SC34: calculated)
The half-life of 11C is 20.364 ± 0.014 min. The most significant measured values are 20.382 ± 0.020 (1975AZ01), 20.334 ± 0.024 (2002WO02), 20.40 ± 0.04 (1969AW02), 20.34 ± 0.04 (1964KA31) and 20.35 ± 0.08 min (1941SM11); the later value is omitted from the weighted average. Other measurements are tabulated in (1968AJ02). The decay populates the 11B ground state; log ft = 3.5921 ± 0.0019. The ratio of K-capture to positron emission is (0.230+0.014-0.011)%. See (1998BA57) for comments on Pauli principle violating anomalous atoms. See also (1995GO34, 2002WO02, 2003SU04) and (1985AJ01).
Elastic and inelastic scattering of 11C + p was measured at θcm = 20 to 50 degrees using E(11C) = 40.6 and 45.3 MeV/A beams (2003JO09). The ground state and excited states at 2.03, 4.37 and 6.47 MeV were observed. The angular distributions for 11C*(0, 4.37) were analyzed in AMD and QRPA models. At E(11C) = 40.6 MeV/A elastic and inelastic proton scattering on 11C were measured in inverse kinematics (2005JO12). States at 11C*(0, 2.02, 4.33, 6.48) were resolved. The elastic scattering data are consistent with Rrmsmatter = 2.33 ± 0.10 fm, and a Jeukenne-Lejeune-Mahaux (JLM) microscopic potential analysis of the Ex = 4.33 MeV (5/2-) and 6.48 MeV (7/2-) state angular distributions are consistent with E2 transition multipolarities. Also see (2003TE12, 2006PE21, 2009UM05) and 12N.
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 mean lifetimes, τm, for 11C*(4.32, 6.90, 7.50) are < 140,< 69 and < 91 fs, respectively. See (1980AJ01) for references. For yields see 12C and (1987DO05).
Particle decay spectroscopy was used to study 11C*(8.10, 8.42, 8.65) which were observed in the coincident 7Be + α particle relative energy spectra (1998LE17). Upper limits for the Γα1/Γα0 decay branching ratios for these states were found to be ≤ 0.03, ≤ 0.01 and ≤ 0.01. A comparison with Γγ values given in (1990AJ01) indicates Γα0/Γ = 0.97 ± 0.03, 0.80 ± 0.10 and ≈ 1.0 for these states, respectively. Excited states above 8.65 MeV are not observed, indicating small α decay branches.
At E(7Li) = 82 MeV no states of 11C are populated (1987AL10).
The resonances at Eα = 0.884 ± 0.008 and 1.376 ± 0.003 MeV [11C*(8.106, 8.419)] have ωγ = 0.331 ± 0.041 and 3.80 ± 0.57 eV, Γγ = 0.350 ± 0.056 and 3.1 ± 1.3 eV, and Γα = 6+12-2 and 12.6 ± 3.8 eV, respectively (1984HA13). See also (1995DE05) for a 3-cluster-model analysis and discussion of the astrophysical importance of this reaction. Also see (1996RE16).
Reported neutron groups are listed in
Gamma-ray branching ratios and multipolarities for 11C levels up to Ex = 7.5 MeV have been studied by (1965OL03): see
The 11C interaction cross sections on Be, C and Al targets were measured at 730 MeV/A (1995OZZZ). Also see (1996KN05).
At E(14N) = 39.3 and 68.3 MeV/A, angular distributions and cross sections were measured and evaluated in a DWIA analysis (1997MIZO).
This reaction has been investigated for Ep = 0.07 to 17.0 MeV. Reported resonances are displayed in 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 to 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: see (1980AJ01).
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
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
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
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 38] and 12.50 MeV [see
Polarization measurements (reaction (a)) have been carried out at Ep = 49.6 MeV for the deuterons to 9B*(0, 2.36): see (1975AJ02). In reaction (b) two strong maxima
are observed in the cross section at Ep ≈ 4.5 and 6.5 MeV: see
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 shows that the 7Be yield constitutes a potential problem if natural boron is used as fuel in CTR devices (1975PE1A).
The parameters of observed resonances are displayed in
Angular distributions of cross section were measured at E(3He) = 34 MeV, and an optical model analysis was used to extract the ANCs for 11C*(0, 4.319, 6.478) (2010AR03). The astrophysically relevant cross sections and S-factors were deduced from the ANCs. Also see (2010TI04) for a shell model analysis of ANCs for this reaction.
Angular distributions have been measured at Eα = 25.1 and 56 MeV [see (1980AJ01)] and at 24.8 and 30.1 MeV (1983VA28; t0, t1).
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.
Pion production yields were measured at Ebrem = 0.03 to 1.2 GeV (1994OUZZ).
Angular distributions for transitions including n0, n1, n2, n3, n4+5, n6, n7 have been measured up to 49.5 MeV [see (1980AJ01, 1985AJ01, 1990AJ01)]. Also see (1986MU08) Epol. p = 13 to 17 MeV, (1990SAZL) Ep = 50, 80 MeV and (1994GA49) Ep = 1 GeV. At Ep = 186 MeV, angular dependent cross sections (θ = 0 to 50 degrees) and polarization transfer coefficients, analyzing powers and induced polarization (θ = 0 to 20 degrees) were measured (1994WA22, 1994RA23, 1995YA12). The quasi-free scattering data are found to agree with a simple Fermi gas model (1994WA22). A multipole decomposition analysis of the data enabled a DWBA investigation of the ΔL = 1 transitions; peaks at Ex = 13 and 16 MeV are found to have Δ L = 0, 1 and 2 components, while a broad peak around Ex = 18 to 23 MeV is dominated by ΔL = 1 components (1995YA12). The G-T matrix elements, which are related to the zero-degree cross sections, are discussed in (1985GR09, 1990TA15) for Ep = 16 to 26 MeV and 160 to 795 MeV, respectively. Polarization transfer coefficients are measured at Ep = 160 MeV (1990TA15) and Ep = 295 MeV (1994WAZW, 1995WA16). See also (1994SH21, 1995SH44, 2009EL09) and 12C.
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) and at E(pol. 3He) = 33 MeV; for references see (1980AJ01, 1985AJ01). At E(3He) = 26 MeV, the Ex = 6.9 to 8.7, (9.78), 10.08 to 12.15, 12.57, 12.65, 13.92 and 14.15 MeV states of 11C are populated including the possible T = 3/2 states displayed in
For reaction (a) 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 Ebrem = 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. 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 11C (and 11B) lies in rather localized energy bands in 12C which are a few MeV wide (1970ME17). Measurements are reported at Ebrem = 20 MeV (1999AB39, 1999AB40, 2000AB35) and Ebrem = 58 MeV (1993AN17); see (1994RY03, 1994VAZX, 1994ZO01, 2000LE38) for comments on knockout reactions above the GDR, also see (1980AJ01, 1985AJ01) and 12C. For reaction (b), the excitation function for n0 emission from the GDR region in 12C was measured at Ee = 126 MeV (2000OI01) and Ee = 129 MeV (1992SU12, 1997SA17, 2002TA19). See also (1991SA14, 1992DR02, 2005SA37). For reactions producing pions see (1990AN26, 1990AR14, 1993LI21, 1994JO05, 1998GL14, 1999BA31, 1999LE35, 2000GL08, 2000SO19, 2003GL03, 2004BO47, 2005GL05, 2006CO19, 2008GL05).
Polarization effects in neutrino-nucleus scattering reactions are discussed in (2008ME03). An analysis of superscaling applied to quasi-elastic neutrino scattering is given in (2008MA21). Discussion of the impact of (ν, ν'n) reactions on 7Li and 11B production in supernovae explosions is given in (2006SU15, 2007SU08). Influence of the nuclear strong quark component on quasi-elastic neutrino scattering is discussed in (1992GA14). Also see (2004ME18, 2004VA09, 2006ME17, 2006ME24).
A study of muon induced backgrounds in large volume scintillators measured σ(100 MeV) = 576 ± 45 μb and σ(190 MeV) = 905 ± 58 μb for production of 11C, and σ(100 MeV) < 1.22 μb and σ(190 MeV) < 2.34 μb for production of 11Be (2000HA33). See (2006BA66) for analysis of 11C production rates in Borexino and (2010AB05) for analysis of production rates in KamLAND.
Angular distributions at Eπ+ = 49.3, 90 and 180 MeV have been obtained to 11C*(0, 2.0, 4.3 + 4.8, 6.5, 8.5). At the same momentum transfer, this reaction and the (p, d) reaction give similar intensities to the low lying states of 11C. T = 3/2 states have been suggested at Ex = 12.5 ± 0.3 and 13.3 MeV: see (1985AJ01). See also (1991KI02, 1992BA57, 1997BO15, 1999KE04). For reaction (b) 11C*(4.32)[5/2-] (and the analog state in 11B) is surprisingly strongly populated for Eπ+ = 60 to 300 MeV: see (1980AJ01, 1985AJ01).
The total cross sections for (n, 2n) reactions on 12C were measured at En = 15 to 40 MeV (1996UN01), En = 20 to 50 MeV (1998KI21), and En = 22.8 to 33.6 MeV (1981AN16). Also see (1997HA21) and references in 13C (1981AJ01, 1986AJ01).
Angular distributions have been measured for Ep = 19 to 800 MeV [see (1968AJ02, 1975AJ02, 1980AJ01, 1985AJ01) for references], at Ep = 45 MeV (2005KI09; to 11C*(0, 2.0, 4.3, 4.8)), at Epol. p = 497 MeV (1984OH06; d0; also Ay) and at Ep = 800 MeV (1984SM04; to 11C* (0, 2.0, 4.3, 4.8, 6.5, 8.1, 8.66 + 8.70, 9.98 ± 0.20, 10.56 ± 0.20, 13.22 ± 0.25)). In the latter experiment 11C*(8.4) and a state at 13.22 ± 0.25 MeV (Γ ≈ 2 MeV) are also reported (1984SM04). See (1991AB04) for an analysis of Cohen-Kurath wavefunctions at Ep = 30.3 MeV, and see (1998CA18) for a Glauber model analysis of Ep = 800 MeV data. States of 11C previously observed in this reaction are displayed in
At 1 GeV the separation energy between Γ ≈ 6 and 13 MeV broad 1p3/2 and 1s1/2 groups is ≈ 17 MeV (1985BE30, 1985DO16). At Ep = 200 MeV, angular distributions were evaluated in a study of the collective influence of the nuclear medium on the NN interaction (1999CA15). At Epol. p = 200 MeV, analyzing powers were measured (1999CA11). The study was evaluating the difference between free NN scattering and quasifree scattering to help improve the understanding of how the presence of a nuclear medium modifies the NN interaction. The excitation function for 11C production via proton spallation on carbon, nitrogen and oxygen was measured for Ep = threshold to 200 MeV (2004KE05) and Ep = 60 to 250 MeV (1999CH50). Measurement of the excitation function for Ep = 95 to 200 MeV determined cross sections for clinical proton therapy applications (1993KO48). Also see (1996MA53) for Ep < 200 MeV and see 12C.
At Ed = 28 MeV the t0 angular distribution was 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 pick-up spectroscopic factor C2S = 2.82 or 3.97 depending on different sets of parameters for 11Cg.s.; 11C*(2.0, 4.32) are also populated; see (1980AJ01). At Epol. d = 200 MeV angular distributions and analyzing powers were measured (1994VA28); a DWBA analysis deduced spectroscopic factors for 11C*(0, 2.0). See also 14N in (1986AJ01), (1980AJ01) for references.
Angular distributions have been measured at many energies to E(3He) = 217 MeV [see (1968AJ02, 1975AJ02, 1980AJ01, 1985AJ01) for references]. Observed states are displayed in At E(3He) = 35.6 MeV DWBA analysis indicates good fits 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+]: see (1980AJ01).
Alpha-γ correlations have been studied for E(3He) = 4.7 to 12 MeV. The results are summarized in 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 analyzing p, t angular correlations: see (1985AJ01). Nuclear rainbow effects are studied at E(3He) = 50 and 60 MeV (1992AD06) and at E(3He) = 98 MeV (1995DA08, 1995DA21). See (1997TE16) for applications in 12C concentration depth profiling.
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(pol. 6Li) = 50 MeV polarization observables were measured for the reaction populating 11Cg.s. (1997KE04). For reaction (b) see (1992SC10, 1993SC02) and 12N.
At E(10B) = 100 MeV, angular distributions have been measured involving 11Bg.s. + 11Cg.s., 11Bg.s. + 11C*(2.00) and 11Cg.s. + 11B*(2.12). See (1985AJ01).
Angular distributions involving 11Cg.s. have been studied at E(12C) = 93.8 and 114 MeV [see (1980AJ01, 1985AJ01)], at 20 MeV/A (1985BO39), at 25, 35, and 50 MeV/A (1988WI09, 1989WI07) and at 344.5 MeV (1992JA10). The strongest peak observed is due to the unresolved 13C*(3.68 + 3.85) + 11C*(4.32) states (1988WI09, 1989WI07). The results are in agreement with the predictions of the exact FRDWBA. Above ≈ 30 MeV/A the angle-integrated cross sections fall off with an approximately exponential shape (1988WI09). A theoretical analysis of spin polarization in nuclei following one nucleon transfer for 12C + 12C at Elab = 140 and 300 MeV is given in (1994YA01).
At E(28Si) = 13.4 GeV/A the 11C activation cross section is σ = 73.5 ± 1.4 (stat.) ± 3.5 (syst.) mb (1990WI09).
This reaction was measured at Ebrem ≈ 36 MeV in the region of the 13C GDR (1993MC02). Also see 13C in (1991AJ01).
At Eπ+ = 32 MeV angular distributions have been obtained for the deuterons to 11C*(0, 6.48): see (1985AJ01).
Angular distributions have been measured for Ep = 26.9 to 65 MeV [see (1980AJ01, 1985AJ01)]. At Ep = 43.7 to 50.5 MeV 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
Angular distributions have been reported at a number of energies in the range Ep = 5.0 to 44.3 MeV for the α0 and α1 groups: see (1975AJ02, 1980AJ01). A DWBA analysis of angular distributions measured for 11C*(0, 2.0, 4.3, 4.8) at Ep = 20 to 45 MeV (2005AB17) found that the reaction proceeds mainly by the direct mechanism. The astrophysical importance of this reaction is discussed in (1998AD12). The excitation function was evaluated as a method to produce 11C for PET applications at Ep = 5 to 25 MeV (2003TA17), and at Ep = 6 to 19 MeV (2003KO72). Also see (1990KO21, 2006TR08). For reaction (b) see (1986VDZY; Ep = 50 MeV).
The excitation function of 14N(d, αn) was measured from threshold to Ed = 12.3 MeV using activation techniques (1998SZ01).
This reaction has been studied at E(10B) = 100 MeV; see (1980AJ01).
Cross sections for neutrino induced reactions on 16O are calculated in (2003KO50).
For reaction (a) γ-rays from Ebrem = 1 GeV were used to evaluate PET radioisotope production (1996BB09). For reaction (b) a 50 TWatt laser was focused on a Ta target, and the intense energy at the laser focus accelerated electrons in the target to relativistic energies; as the electrons stopped Bremsstrahlung photons were produced with energies above 10 MeV. The high energy photons induced photo-breakup reactions in the Ta and 11C ions were produced (2000LE02).
At Ed = 80 MeV, angular distributions for 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).
At E(9Be) = 70 MeV 11C states at Ex = 8.65, 9.85, 10.7 and 12.1 MeV were observed in the relative energy spectrum of 7Be + α particles (2004SO19, 2004SO28, 2005SO13). There is weak evidence for peaks corresponding to 11C*(12.6, 13.4). Observation of 11C*(12.1), which is assumed to be the T = 3/2 analog of the 11Be ground state, may indicate a significant T = 1/2 isospin mixing.
Total reaction cross sections for 11C + 28Si were measured at E(11C) = 15 to 53 MeV/A (2006WA18). A Glauber model analysis was used to deduce the 11C Rrmsmatter = 2.18 ± 0.26 fm.
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