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12N (2017KE05)

(See Table 12.44 preview 12.44 (in PDF or PS) and Energy Level Diagrams for 12N and Isobar Diagram)

μ = 4571 (1) nm (2010ZH03). See also μ = 4573 (5) nm (1968SU05) and (2013MA60).
Q = +9.8 ± 0.9 mb (1998MI10).
<(rmatterrms)2>1/2 = 2.40 - 2.50 fm; i.e., see (2006WA18, 2010LI18).

An analysis of the T = 1 states of 12B, 12C and 12N with Jπ = 1+, 2+ and 0+ using the quadratic form of the IMME is reported in (1998BR09). A similar report is given in (2013LA29) which also included the 2- and 1- states. See also (2009BA41, 2014MA56).

1. 12N(β+)12C Qm = 17.3381

The half-life of 12N is 11.000 ± 0.016 ms (1978AL01); see also T1/2 = 10.95 ± 0.05 ms (1963FI05), 11.43 ± 0.05 ms (1958VE20), 11.0 ± 0.1 ms (1963PE10), 11.1 ± 0.2 ms (1962PO02) and 11.2 ± 0.4 ms (1959FA03). 12N decays to 12C*(0, 4.44, 7.65, 10.3, 12.71, 15.11): see Table 12.42 preview 12.42 (in PDF or PS). See (2015MO10) for discussion of the β and neutrino spectra shapes. Since the transitions to 12C*(0, 4.4) are allowed, the Jπ of 12Ng.s. is 1+. Measurement of the magnetic quadrupole moment, via β-NMR techniques, yields Q = +9.8 ± 0.9 mb (1998MI10). See also (1998MI20).

Measurements of βγ correlations in aligned 12N (and 12B) nuclei can provide information on conservation of vector currents without second-class currents (1985MI1A, 1985GR1A, 1995GO34: reviews) and (1978BR18, 1979MA31, 1987MI20, 1990CA10, 1993MI32, 1994MO23, 1995KO28, 1998MA27, 1999MI04, 2002MI01, 2003SM02). Analysis of modern experiments yields the axial charge, y = 4.90 ± 0.10 (2002MI01), which is consistent with an in-medium renormalization of hadron masses; the data implies an in-medium nuclear mass reduction of (16 ± 4)%.

The longitudinal polarization of positrons emitted from polarized 12N is analyzed and sets a lower limit M(W gauge boson) ≥ 310 GeV/c (1996AL23, 1998SE04, 2001TH18) for the right handed guage boson contributing to electro-weak interaction; these results are consistent with the standard model.

Limits on the G-parity irregular induced tensor coefficient, fT, in the weak nucleon axial vector current are found as 2MfT/fA = -0.15 ± 0.12 (stat.) ± 0.05 (theory) from analysis of β-ray angular distributions from spin aligned 12N and 12B ions (1998MI14, 1999MI41, 2000MI11, 2002MI03, 2002MI36, 2002MI49, 2003MI24).

See also (1991LI32, 1998MA27, 2013MI10) for 12N polarization methods.

2. 1H(11C, α + 8B) Qm = -7.4072

The Ex(12N) = 8.7 to 9.9 MeV region of the 8B(α, p) reaction was studied in inverse kinematics by impinging E(11C) = 98 to 110 MeV beams on 720 μg/cm2 CH2 targets (ΔE ≈ 100 keV) and detecting the α+8B reaction products (2004RE31). The cross sections for the complementary reaction, deduced via the Detailed Balance equation, increase steadily from about 50 nb to 20 mb with only a slight enhancement of near 9.1 MeV. This cross section, which is relevant to the astrophysical hot pp-chain, is roughly two orders of magnitude larger than previously expected. See also (1990DE21).

3. 2H(11C, 12N)n Qm = -1.6234

Indirect studies of the astrophysically important 11C(p, γ) reaction were carried out by analyzing angular dependent cross sections for the 2H(11C, 12Ng.s.) reaction at (θcm ≤ 33.8°) and E(11C) = 9.8 MeV (2003LI51, 2005LI40, 2006LI62), and at (10.9° ≤ θcm ≤ 72°) and E(11C) = 150 MeV (2011LE25). While the earlier measurement confirmed the dominant mechanism is direct capture to the ground state, their results (ANC = 2.86 ± 0.91 fm-1) are limited by low statistics. The later measurement found the ANC as (C12Neff)2 = 1.83 ± 0.27 fm-1, and in calculations where they folded in resonant capture to the first and second excited states and interference contributions they obtained the astrophysical S-factor(0) = 0.097 ± 0.020 keV ⋅ b, which is significantly higher than theoretical predictions.

Analogous to determination of the 2H(11C, n) ANC, the 2H(11B, p) θ ≤ 160° angular distribution data from (1967SC29, 1974FI1D, 2001LI45) were analyzed in (2007GU01) to determine the 12B*(0, 0.95, 1.67) → 11B + n ANCs; then by charge symmetry the corresponding 12N → 11C + p ANC values were deduced. In addition to determining astrophysical S-factors for capture to the ground, first and second excited states, Γp = 0.91 ± 0.29 keV and 99 ± 20 keV were deduced for 12N*(0.95, 1.19), respectively. See also (2005SH39, 2005TI07, 2005TI14, 2012OK02).

4. 9Be, C, 27Al, Si(12N, X)

The 12N total reaction and interaction cross sections were measured on 9Be, natC and 27Al at E(12N) = 730 MeV/A (1995OZ01) and on natSi at E(12N) = 20 to 42 MeV/A (2006WA18) and E(12N) = 34.9 MeV/A (2010LI18). The cross sections were analyzed in Glauber models to deduce matter radii of Rmatterrms ≈ 2.40 - 2.50 fm. Spectroscopic factors to 11C*(0, 2.0, 4.32, 4.80) are calculated and compared with the data in (2006WA18). See also (2001OZ04).

5. 9Be(13O, 12N*)10B Qm = 5.0747

An E(13O) = 30.3 MeV/A beam, produced via the 1H(14N, 13O) reaction, impinged on a 9Be target where 1n and 1p knockout reactions populated 12N and 12O (2012JA11). Excited 12N decayed into 11C + p and 10B + 2p. In (2012JA11), kinematic reconstruction of the relative energies found evidence for 12N states at Ex = 968 ± 10 keV [11C + p] and Ex = 12196 ± 29 keV (Γ < 110 keV: Jπ = 0+) and ≈ 14200 keV [10B + 2p]. A followup analysis (2013SO11) focused on 13O and 12N events involving the 12N second excited state; Ex = 1.179 ± 0.017 MeV and Γ = 55 ± 20 keV were deduced for this Jπ = 2- resonance that decays 100% via 11C + p. In (2012JA11), the 12N*(12196) state is interpreted as the IAS of 12Og.s., and a comparison using the IMME formula finds the T = 2 quintet for A = 12 can be fit with a quadratic form. See also 12O reaction 1.

6. (a) 11C(p, γ)12N Qm = 0.6012
(b) 11C(p, p) Eb = 0.6012

The 11C(p, γ) reaction is part of the hot pp chain (1989WI24), which can produce CNO seed nuclei earlier than the triple-α process; see discussion in (1990DE21, 2006LI62, 2011LE25). At present there are no direct measurements of the capture cross section, which is expected to be determined by direct capture and resonant capture to 12N*(0.96[2+], 1.19[2-]). Estimates of Γγ = 2.59 meV and 1.91 meV were deduced in (1989WI24) by analogy with 12B*(2+) and from systematics given in (1979EN05), respectively. Subsequent experimental (i.e. see reaction 19) and theoretical (1990DE21, 1999DE03, 2003TI01) analysis suggests Γγ(2-) ≫ 2 meV leading to a much higher reaction rate than estimated in (1989WI24). See also (1993TI01, 2010HU11).

The 11C + p elastic scattering in thick target inverse kinematics (TTIK) has been used to provide important data for the capture reaction. An E(11C) = 3.5 MeV/A beam was stopped in a thick (CH2)n target, and scattered protons were detected at θlab < 5°; using the p and 11C stopping powers in the CH2 target the 11C + p excitation function was reconstructed from the observed proton energy spectrum. The 12N*(1.2, 1.8, 2.4, 3.1, 3.6) levels are observed in the excitation spectrum, and Jπ = 3- and (2)+ are deduced for 12N*(3.1, 3.6) (2003KU36, 2003TE01, 2003TE09, 2003TE12). TTIK was also employed to probe the Ex = 2 to 11 MeV region (2006PE21); at E(11C) = 73.8 and 125 MeV, elastically scattered protons from a CH2 target were detected at θlab = 0°, 5°, 10° and 15°, and at 99.8 MeV, protons elastically scattered in a CH4 gas filled chamber were detected at θlab = 0°, 11.5°, 12.5° and 16.5°. Table 12.45 preview 12.45 (in PDF or PS) displays 12N levels deduced from R-matrix analysis of the (2006PE21) excitation function that relied on known 12N and 12B levels. See also discussion in (2016HO14).

7. 10B(3He, n)12N Qm = 1.5725

Parameters for observed neutron groups, mainly from (1974FU11: E(3He) = 12.5 and 13 MeV) are displayed in Table 12.46 preview 12.46 (in PDF or PS). Angular distributions have been studied at E(3He) = 2.5 and 3.6, 2.4, 2.75 and 2.94, and 4.0 and 5.8 MeV: see references in (1968AJ02), and at E(3He) = 11, and 12.5 and 13 MeV: see references in (1975AJ02).

8. (a) 12C(γ, π-)12N Qm = -156.9083
(b) 12C(γ, π0π-)12N Qm = -291.8849

States at Ex ≈ 0, 1 and 4 MeV are populated in photo-pion production (1979PA06); see also (1976BE39: Ebrem = 170 MeV), (1983SC11: Ebrem = 190 MeV), and (1976WA07: Ebrem = 250 MeV). At higher energies cross sections in the Δ resonance region were studied with (1974BO47: Ebrem = 345 MeV), (1979BO23: Ebrem = 360 MeV), (1974EP02: Ebrem = 375 MeV), (1982AR06: Ebrem = 390 MeV), (1982TO10, 1985TO14: Ebrem = 400 MeV), (1990AN26: Ebrem = 450 MeV); (1977BA60, 1978BA50: Ebrem = 850 MeV), (1973GO44: Ebrem = 1200 MeV), and (1980AL25: Ebrem = 4.5 GeV); see a review in (1988KA41).

The reaction mechanism for 12C(γ, π0π-) is investigated at Ebrem = 400 to 460 MeV in (2002ME22); see also (2003ME32, 2003RO20, 2003VI09, 2003VI11, 2004MU17).

9. 12C(νe, e-) Qm = -17.34

The q2-dependence of the weak axial vector form factor, FA(q2), was deduced from the decay electron energy spectrum; analysis indicates FA(q2 = 0) = 0.73+0.11-0.10, which compares well with FA(q2 = 0) = 0.711 deduced from β-decay (1994BO41: KARMEN Collaboration).

Neutrino beams produced via π+ → μ+ + νμ followed by μ+ → e+ + νe + ν̄μ; (E(νe) ≈ 26 to 50 MeV) have been used to measure the flux averaged cross section for Charge Current interactions (CC); present results, which are important for systematics in neutrino oscillation experiments, are summarized in Table 12.47 preview 12.47 (in PDF or PS). The first measurement, E225 (1990AL09, 1992KR05), was carried out at LAMPF and produced cross section values for the exclusive 12C(νe, e-)12Ng.s. reaction (identified by a scattered electron in coincidence with the β+ from 12N decay) and inclusive 12C(νe, e-)[12Ng.s.+12N*] reaction; the cross sections are often evaluated to deduce the 12C(νe, e-)12N* yields. Later efforts by the KARMEN collaboration (1992BO11, 1993BO12, 1994BO34, 1994BO41, 1994KR14, 1996KL07, 1998AR04, 2008EI01) and LSND collaboration (1997AT02, 2001AU09) have produced results in reasonable agreement. See an overview in (2003KO50).

In general, theoretical estimates of the reaction cross sections are in good agreement with measured values and have been carried out using QRPA/CRPA models (1992KO07, 1996KO32, 1997AU05, 1998IM02, 1999KO24, 2000VO13, 2001AU05, 2001VO18, 2002JA03, 2005BO44, 2005KR06, 2008PA06, 2010CH05, 2011SA04), Shell models (2000VO13, 2001AU05, 2001VO18, 2002AU01, 2003HA17, 2012SU15) and other approaches (1996EN06, 1996KO03, 2003HA44, 2004SA67, 2013PA06, 2013SO15, 2016GA35).

The role of neutrino interactions for nucleosynthesis in supernovae explosions is discussed in (2006SU15, 2007SU08, 2008PA05, 2009CH49, 2013PA06).

10. 12C(νμ, μ-)12N Qm = -122.9965

A beam of νμ from in-flight decay of π+ was used to determine the flux averaged cross sections for populating 12N ground and excited states (2002AU03: LSND Collaboration). Detectors searching for neutrino oscillations are mainly mineral oil (carbon) based scintillators, and hence cross sections on 12C for neutrinos from pion decay are vital for data analysis. For these measurements, the neutrino beam energy spectrum extended to slightly above 250 MeV so reactions occurred for Eν = 150 (threshold) to 250 MeV. The exclusive cross section to 12Ng.s., which requires the coincidence of a μ- with a delayed β+ from 12N decay, is σ = (5.6 ± 0.8 (stat.) ± 1.0 (sys.)) × 10-41 cm2, while the inclusive cross sections, which required only detection of the emitted μ-, is σ = (10.6 ± 0.3 (stat.) ± 1.8 (sys.)) × 10-40 cm2. The 12N(νμ, μ-)12N* cross section is roughly 200 times greater than the νe induced reaction.

See prior results from the collaboration in (1997AT03). Note: an earlier LAMPF measurement had significantly fewer events (1992KO18) and was incompatible with the LSND results. See also (2003KO50).

Theoretical analyses of the cross sections have been carried out using QRPA/CRPA models (1996KO32, 1997AU05, 2001JA12, 2005BO44, 2005KR06, 2006CO15, 2006CO16, 2008PA06, 2011SA04), shell models (1999HA32, 2002AU01) and other approaches (2004ME12, 2004SA67, 2006JA04, 2006VA09, 2011KI06, 2014KI06, 2016PA43, 2016VA08). Special attention has been focused on the reaction channel populating 12N*; this contribution to the reaction cross section is generally over predicted by roughly a factor of two (1995KO40, 1995UM02, 1996EN06, 1996KO03, 1997KO04, 1998IM02, 1999KO24, 2000HA17, 2000VO13, 2001AU05, 2001VO18, 2002JA03, 2003HA17).

The scaling and superscaling approaches for relating the relativistic (e, e') and (νμ, μ-) cross sections provide a reasonable description and are examined for energies up to the quasi-elastic scattering and Δ-resonance regions in (2003HA44, 2005AM09, 2005CA54, 2006BA17, 2006BA62, 2006CA22, 2008IV01, 2009AN06, 2015AM02, 2015PA35, 2016IV03).

11. 12C(p, n)12N Qm = -18.1204

States populated in 12C(p, n) are displayed in Table 12.48 preview 12.48 (in PDF or PS). At Ep = 135 MeV, Jπ values are deduced from a DWIA analysis of θ = 0° - 45° angular distributions (1996AN08); see earlier measurements and analysis at Ep = 30.5 and 49.5 MeV (1970CL01) and at 160 MeV (1984GA11). At Epol. p = 197 and 295 MeV cross sections, angular distributions, and spin observables were measured (1996SA11). The peak at Ex = 4.5 MeV is consistent with a Jπ = 2- assignment, but at Ex = 7.5 MeV the strength is inconsistent with the predicted Jπ = 1- because the sign of DNN is negative; it should be positive. Contributions from additional states are suggested to explain the negative DNN(0) (1996SA11). Unresolved angular distributions over the range Ex = 2 to 17 MeV (and θ = 5°-13°) are dominated by l = 1 transitions (1984GA11).

Angular distributions have also been studied at Ep = 35 and 40 MeV (1987OH04: n0, n1, n2; DWBA), 61.8 and 119.8 MeV (1979GO16, 1980AN05: n0, n1) , 99.1 MeV (1980KN02: n0, n1), 120, 160 and 200 MeV (1981RA12: n0, n1) [the spin-isospin term of the effective interaction appears to be almost energy independent over the latter energy interval], and at 144 MeV (1980MO10: n0). See also (1994GA49, 2010AD18). The backward angle scattering distribution for n0 measured at Ep = 200 MeV was found to be five times larger than expected (1996YU02). At Ep = 647 and 800 MeV, the spectra show a narrow high energy peak and a broad bump at lower energies associated with pion production (1976CA17).

The θ = 0° (L = 0) cross sections to 12Ng.s. at Ep = 61.8 and 119.8 MeV (1979GO16, 1980AN05), 280 MeV (1990MI10), 160, 200 and 795 MeV (2001PR02), 492 MeV(1989RA09) have been compared with the Gamow-Teller transition strengths and to the strengths for population of the 12C*(15.11) (1982AN08) and 12Bg.s. members of the T = 1 isospin triad (1990MI10). See also (1980AN05, 2002DM01). In (1987TA13) analysis of the θ = 0° (L = 0) cross sections measured for G-T transitions over a broad range of targets yielded a straightforward relationship between the cross section and B(GT). See also (1989RA09). A systematic analysis of 12-19C(p, n) reactions is given in (2016TA07).

At Epol. p = 160 and 186 MeV spin observables were measured for θlab = 0° to 50°; prominent peaks at 12N*(0, 0.96, 1.2, 4.5, 7) were evaluated via multipole decomposition analysis (1993YA11, 1994RA23, 1995YA12). At Ep = 296 MeV, cross sections and polarization transfer observables were analyzed up to Ex ≈ 10 MeV; the Ex ≈ 7 MeV group is dominated by Jπ = 2- strength and a strong spin-flip strength is found in the continuum (2008DO02). See also (2007WA40: Epol. p = 296 MeV) and (2005WA36).

The polarization transfer coefficients, DNN(0°), were measured at Epol. p = 295 MeV (1995WA16), the large negative values measured for Ex up to 50 MeV suggest a stronger spin-flip strength than what has been observed at lower bombarding energies. Results at Epol. p = 318 and 494 (1993ME06) indicate that medium modified effective N-N interactions play a role. See also measurements at Epol. p = 50 and 72 MeV (1991LI32), Ep = 296 MeV (2008DO02), Table 12.49 preview 12.49 (in PDF or PS), and analysis in (1998HI02, 1999AN32, 2000KI03).

Cross sections and analyzing powers have been measured for quasifree neutron knockout (1994WA22: Epol. p = 186 MeV, 1991TA13: Ep = 494 and 795 MeV, 1993HI01: Epol. p = 290 and 420 MeV) and are found to be similar to those for free NN scattering (1993HI01). See also (1992WA19, 1993DE33, 1999NA43). Measurements on the spin-longitudinal and spin-transverse strength functions are given in (1984TA07: Ep = 160 MeV, 2002HA14: Epol. p = 197 MeV, 2004WA14: Ep = 345 MeV, 1999WA08: Epol. p = 346 MeV, 1993CH13, 1994TA24: Epol. p = 495 MeV, 1994PR08, 1995PR04: Epol. p = 495 and 795 MeV). See discussion in (1993HO04, 1993SA30, 1994DE29, 1994HO15, 1994HO18, 1994IC04, 1995DE44, 1996GA20, 1999YO02, 2001KA19, 2002IC02, 2002NA17).

At Epol. p = 65 MeV the spin transfer coefficient Ky'y(0°) for pol. n0 + pol. n1 has been measured by (1984SA12). See also (1987LI29, 1987RA32). Evidence for pionic and ρ-mesonic correlation effects is deduced from analysis of polarization transfer coefficients measured at Ep = 296 MeV (2009DO12). See also (1994DM03, 1994HE06, 1996OS02, 1996PR03, 1998DO15, 1998IO03, 2002DA20, 2002IC02, 2002TO07, 2016DE06).

12. 12C(3He, t)12N Qm = -17.3567

Measurements of the 12C(3He, t) reaction are summarized in Table 12.50 preview 12.50 (in PDF or PS). Observed triton groups are displayed in Table 12.46 preview 12.46 (in PDF or PS). The 12N*(0, 0.96, 1.19, 2.42, 4.25) triton group angular distributions (corrected for phase-space and isospin factors) are similar to those of inelastically scattered 3He to 12C*(15.11, 16.11, 16.58, 17.77, 19.57) strongly suggesting isobaric analogs (1969BA06, 1970AR05, 1976CE02, 1982TA05). Following this suggestion, if 12C*(17.77) and 12N*(2.42) are analogs, then the latter is a 0+ state (1976CE02). Relatively narrow levels at 12N*(4.25, 5.32, 6.10, 7.13) are reported in 10B(3He, n), while broader levels at 12N*(4.15, 5.23) are observed in this reaction; it is therefore suggested that the selectivity is greater in the (3He, n) reaction and that (3He, t) populates unresolved states (1976MA15).

More states are observed in 12B than in 12N, indicating that some analog states are missing. With the possible exception of the relatively narrow states, 12N*(9.42, 9.90), the other reported groups with Ex > 6 MeV may be due to unresolved groups (1976MA15). See also (1975GO1L, 1978TA1M).

At θ ≈ 0° the Gamow-Teller and spin-flip ΔL = 1 resonances are strongly populated; cross sections have been measured (1991JA04: E = 76, 200 MeV), (1994AK02: 450 MeV), (2007ZE06: 420 MeV). The Jπ = 1+, 2+, 2-, 0+, 2-, 3-, 1- values are deduced for 12N*(0, 960, 1190, 2439, 4250, 5348, 7130), respectively (1991JA04). A broad study of the B(GT) systematics finds σGT = 109/A0.65, where the GT unit cross section, σGT, is related to the known B(GT) values from β-decay and the dσ/dΩcm cross section for zero momentum transfer (2011PE12).

In (1994AK02, 1994HA40, 1998IN02, 1998HA43: 450 MeV) proton decay from excited 12N states was measured in coincidence with σ(Et, θ = 0°); 12N*(4.16, 6.0, 9.9) were correlated with p0-decay to the 11C Jπ = 3/2- ground state, while 12N*(7.4, 8.4, 9.9) were correlated with p1-decay to 11C*( 2.0[Jπ = 1/2-]). Preliminary analysis indicates Jπ = (2-), (1-) and (0-) for 12N*(6.4, 7.4, 9.9) respectively.

Angular distributions have been reported to many states. 12N*(4, 7.1) are reached via an l = 1 transfer (1983EL05). At 81 MeV, (1983ST10) carried out a DWBA analysis for states up to Ex = 7.4 MeV. At E(3He) = 197 MeV (θ = 0°) the spectrum shows 12N*(0, 0.96), an ≈ 1 MeV wide state at 4.3 MeV (possibly 2-, 4-) and the GDR at ≈ 10 MeV ( ≈ 84% of the strength is 1-) (1984TA11). 12N*(4.) is assumed to be the analog of the Jπ = 2- isovector magnetic dipole state while 12N*(7.) corresponds to a group of states with Jπ = 1- strength that is the analog of the GDR (1991GR03). The 12N and 12B spin-dipole resonances, populated via 12C(3He, t)12N and 12C(d, 2He)12B reactions, are compared and discussed in (1998IN02).

The spectra of inelastically scattered 3He ions (see 12C) and of tritons have been studied at E(3He) = 170 MeV (1982TA05). The triton spectrum has been compared with photoabsorption results (1984TA11, 1991GR03, 1998IN02). (1982TA05) conclude that the isovector GDR is preferentially excited in the (3He, t) process while the (3He, 3He) process preferentially excites the isoscalar giant multipole resonances. No structure is observed between Ex = 15 and 70 MeV (1984TA11).

Analysis of data in the quasielastic scattering energy region (1987BE25) is given in (1996GA20, 1992WA19, 1996KE04). At E(3He) = 0.6 to 2.3 GeV the reaction appears to be single-step direct and is well described by DWIA (1987BE25).

Delta isobar excitations have been studied at 1.5, 2.0 and 2.3 GeV (1986CO03) and at 4.4 to 10.8 GeV/c (1984AB06, 1988AB08). In later studies (1991HE12, 1992HE08, 1993RO09) π+ + protons were detected following decay of the Δ, and the width of the resonance was evaluated. The Δ excitation peak observed in the 12C(3He, t)12N reaction is shifted from that found in the 12C(d, 2He)12B reaction, see discussion in (1984GA36, 1984GE1A, 1985RO1N, 1986EL1C, 1986GA1P, 1987EL08, 1987EL14, 1988RO17). See also (1990AR05, 1990DE49, 1990GA19, 1991DE31, 1993DM01, 1993FE10, 1993OS03, 1994DM03, 1994HE06, 1994OS02, 1994SN01, 1994UD01, 2002DA20).

Measurements and discussion on Dnn(0°) ≈ 1/3, the spin transfer coefficient, are given in (1994DM03, 1998KI10, 2000KI03).

13. 12C(π+, π0)12N Qm = -12.7445

At Eπ± = 165 MeV, excitation of the 12N and 12B isovector analog giant E1 resonances, built on 12Cg.s., is observed (1994HA41). Earlier studies of (π±, π0) evaluated the A and isospin dependence of the cross section to investigate the Δ-nucleus interaction (1983AS01, 1984AS05, 1987OS05, 1990BE41, 1990IM02).

14. 12C(6Li, 6He)12N Qm = -20.8433

Angular distributions have been studied to 12Ng.s. at E(6Li) = 84, 150 and 210 MeV (1987WI09), E(6Li) = 93 MeV (1984GL06), E(6Li) = 100 MeV (1994LA10), E(6Li) = 156 MeV (1990MO13, 1993SC02) and E(6Li) = 210 MeV (1986AN29). At bombarding energies up to 210 MeV the reaction mechanism is dominated by two-step processes, but it is suggested that one step processes will dominate above 300 MeV (1987WI09). At the higher beam energies 12N*(1.0) is also populated as is a broad structure near 4.25 MeV. The forward angle cross sections for the GT transitions are found to be proportional to the β-decay strength for 12C and other targets (1986AN29).

Proton angular distributions (p0, p1 and p2+3) of groups near 12N*(4.2, 5.35, 6.4, 7.4, 9.5, 12) were analyzed via Legendre polynomial fits (1993SC02) to deduce spin information; the results are consistent with the accepted spin values, with the exception of the Ex = 6.4 MeV resonance, where J > 3 is required while prior studies indicate Jπ = 1-.

15. 12C(12C, 12N)12B Qm = -30.7075

The Ex = 0, 0.96 MeV states of 12N and 12B are populated in 12C(12C, 12B) reactions at E(12C) = 70 MeV (1986WI05, 1991AN12). Since only the 12Ng.s. is bound, emphasis is typically placed on the 12C(12C, 12N) reaction, which isolates 12B excited states. See further discussion in 12B reaction 35 12C(12C, 12N).

Coherent pion production was measured using the 12C(12C, 12+) reaction at 1.1 GeV/A (2005BO22).

16. 12C(13C, 13B)12N Qm = -30.7752

At E(13C) = 30 MeV/A 12N*(0, 1.0) are populated but the dominant groups in the forward direction are broad structures at Ex = 4.2 and 7.5 MeV attributed to Jπ = 2- (SFGDR) and 1- (GDR) states (1986VO02, 1988VO06). See analysis of the ground-state charge exchange reaction in (1999MA18).

17. 14N(p, t)12N Qm = -22.1355

At Ep = 38 MeV triton groups are reported to states up to Ex = 7.3 MeV (2015CH50); see Table 12.51 preview 12.51 (in PDF or PS); see also discussion in (2016HO14). At Ep = 43.7 MeV, triton groups are observed to 12Ng.s. and to the first excited state: Ex = 0.963 ± 0.030 MeV (1967CE1B: private communication). At Ep = 51.9 MeV angular distributions of the tritons to 12N*(0, 0.96) and of the 3He ions to the analog T = 1 states [12C*(15.11, 16.11)] have been measured (1976YO03). At Ep = 52.5 MeV the angular distribution to 12N*(2.42) is consistent with Jπ = 0+ (1976CE02). The atomic mass excess of 12N, 17338 ± 1 keV, is derived from this reaction in (1976NO1J).

18. 14N(11C, 12N)13C Qm = -6.9494

Angular distributions for 14N(11C, 12N) were measured at E(11C) = 110 MeV (2001TR04, 2002GA11, 2002GA44, 2003TA02) in order to determine the 12N → 11C + p ANC, which is related to the non-resonant 11C(p, γ) reaction rate. The value (Cpeff12N)2 = (Cp1/212N)2 + (Cp3/212N)2 = 1.73 ± 0.25 fm-1 was deduced, implying a significantly larger astrophysical S-factor than previously deduced. See also (2003KR14, 2003TR09, 2005TI07, 2005TI14, 2006MU15, 2012OK02) and reaction 11C(p, γ).

19. 208Pb(12N, 11C + p) Qm = -0.6012

At E(12N) = 65.5 MeV/A the Coulomb dissociation of 12N was measured on a 208Pb target and the photo-breakup excitation function was deduced from the kinematic reconstruction of the p + 11C momenta (1995LE27). Analysis indicates Γγ = 6.0+7.0-3.5 meV for 12N*(1.19) and C2S = 0.40 ± 0.25 for the direct capture spectroscopic factor. See measurements at E(12N) = 77 MeV/A in (2004MIZW) and (2005TY02). See also discussion in (2015MU08).