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12N (1990AJ01)

(See Energy Level Diagrams for 12N)

GENERAL: See also (1985AJ01) and Table 12.22 preview 12.22 [Table of Energy Levels] (in PDF or PS) here.

Model calculations:(1984KA1H, 1984SA19).

Astrophysical questions:(1985CA41, 1987RA1D, 1988CA26, 1988LE08, 1989KR1C).

Applied work:(1987KU17, 1987MI24).

Complex reactions involving 12N:(1985NO1E, 1986GA1P, 1987BA1T, 1987RI03, 1988BE02, 1988LE08).

Muon and neutrino capture and reactions:(1986DA1J, 1987KR1L, 1988AL1O, 1988BO1X, 1988FU08, 1988MI1H, 1988MI20, 1989DR1A, 1989KR1C, 1989MI1I).

Pion capture and reactions:(1983AS01, 1984AS05, 1988HA12, 1988KIZW).

Other topics:(1984KA1H, 1984SA19, 1985AN28, 1986YA1F).

Ground-state properties of 12N:(1985AN28, 1985NA1A, 1986GL1A, 1986HA1P, 1987VA26, 1988VA03).

μ = +0.4573 (5) nm (1978LEZA).

1. 12N(β+)12C Qm = 17.338

The half-life of 12N is 11.000 ± 0.016 ms: 12N decays to 12C*(0, 4.44, 7.65, 10.3, 12.71, 15.11): see Table 12.21 preview 12.21 (in PDF or PS). Since the transitions to 12C*(0, 4.4) are allowed the Jπ of 12Ng.s. is 1+. For measurements of the angular distribution functions from aligned 12N nuclei see (1986MI1P, 1986MI1T, 1987MI1P). See also (1985AJ01), (1986CA1P, 1986MI1Q, 1986MI1R, 1987MI20, 1987VA1P), (1985BA2L; applied), (1985GR1A, 1985MI1A) and (1984DU1E, 1985MO13, 1986KE1A, 1986KO2C, 1986TO1A, 1987DR1A, 1987SA1N, 1988AL1E, 1988SA12, 1989SA1H; theor.).

2. 10B(3He, n) 12N Qm = 1.573

Observed neutron groups are displayed in Table 12.23 (in PDF or PS).

3. 12C(γ, π-)12N Qm = -156.907

The total cross section has been measured from threshold to Ee = 360 MeV: see (1985AJ01).

4. 12C(p, n)12N Qm = -18.120

Angular distributions have been studied at Ep = 30.5 to 200 MeV [see (1980AJ01, 1985AJ01)] and at 35 and 40 MeV (1987OH04; n0, n1, n2; DWBA), at 160 MeV (1984GA11; n0; also Ay; comparison with (p, p') to 12C*(15.1)). The angular distribution to 12N(4.2) [u?] is consistent with Jπ = 2- predicted by theory. A structure at Ex ≈ 7.2 MeV is also observed. Unresolved angular distributions over the range Ex = 2 - 17 MeV (and θ = 5° - 13°) are dominated by l = 1 transitions (1984GA11) [as would be expected at those angles]. (1987TA13, 1989RA09) discuss the relationships between the GT strength and the 0° differential cross section in this and other (p, n) reactions. At E pol. p = 65 MeV the spin transfer coefficient Ky'y (0°) for pol. n0 + pol. n1 has been measured by (1984SA12). See also (1985AJ01), 13N in (1991AJ01), (1984BA1R, 1988HIZX, 1988NI1C, 1988TAZY, 1989PRZZ), (1988LE08; astrophysics), (1985BA2L), (1984GA36, 1984TAZS, 1985SH1C, 1986GA1P, 1986LI1T, 1987EL08, 1987EL14, 1987LI29, 1987RA32) and (1984SA19, 1987BE1D, 1988HO09, 1988PI08, 1988UD03; theor.).

5. 12C(3He, t)12N Qm = -17.357

Observed triton groups are displayed in Table 12.23 preview 12.23 (in PDF or PS). Angular distributions of inelastically scattered 3He to 12C*(15.11, 16.11, 16.58, 17.77, 19.57) have been compared with those of tritons to 12N*(0, 0.96, 1.19, 2.42, 4.25). When the 3He cross sections are corrected for phase-space and isospin factors the angular distributions are closely similar to those for the triton groups, strongly suggesting isobaric analogs: see (1980AJ01) for references. [If 12C*(17.77) and 12N*(2.42) are analogs, then the latter is a 0+ state.] Angular distributions have been reported at 81 MeV (1983ST10) [to many of the states shown in Table 12.23 preview 12.23 (in PDF or PS)]. [Compare the 12B and the 12N level structure: it is clear that not all the analog states have been observed in 12N.] Angular distributions have also been studied at E(3He) = 0.6 to 2 GeV (1987BE25; to 12N*(0 + 0.96, 4., 7.). 12N*(4.) is assumed to be a 2- state while 12N*(7.) corresponds to a group of 1- states. The reaction appears to be single-step direct and is well described by DWIA (1987BE25). 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-). No structure is observed between Ex = 15 and 70 MeV (1984TA11). The spectra of inelastically scattered 3He ions (see 12C) and of tritons have been studied at E(3He) = 170 MeV. The triton spectrum has been compared with photoabsorption results. (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. Delta isobar excitation has been studied at 1.5, 2.0 and 2.3 GeV (1986CO03). See also (1988AB08), (1984AB06, 1988JA1F, 1989JAZY), (1984GA36, 1984GE1A, 1985RO1N, 1986EL1C, 1986GA1P, 1987EL08, 1987EL14, 1988RO17) and (1984CH1N, 1985JA13, 1987DM02, 1987GU07, 1988ES1A, 1988UD03; theor.).

6. 12C(6Li, 6He)12N

At E(6Li) = 25 and 35 MeV/A angular distributions have been studied to 12Ng.s. (1987WI09). At the higher energy 12N*(1.0) is also populated as is a broad structure near 4.25 MeV. At forward angles the cross section for the GT transition in this and in other (6Li, 6He) reactions is found to be proportional to the β-decay strength (1986AN29). See also (1984GL06) and (1987AU04, 1988AN06, 1988AU1E, 1989AU1B).

7. 12C(12C, 12B)12N Qm = -30.708

See 12B.

8. 12C(13C, 13B)12N Qm = -30.776

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 2- and 1- states (1986VO02, 1988VO06).

9. 12C(14N, 14C)12N Qm = -17.495

See (1986BA16, 1986EL1C, 1986RO1Q).

10. 14N(p, t)12N Qm = -22.136

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. At Ep = 52.5 MeV the angular distribution to 12N*(2.44) has been studied. See (1980AJ01) for references.