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13N (59AJ76)(See the Energy Level Diagram for 13N) GENERAL: See also Table 13.9 [Table of Energy Levels] (in PDF or PS). Theory: See (LA55B, DA56G, FR58B, HA58D, SK58).
Recent determinations of the half-life give 10.05 ± 0.03 min (CH53C), 10.08 ± 0.04 min (WI55H), 10.07 ± 0.06 min (NO57A), 9.96 ± 0.03 min (AR58), 9.96 ± 0.03 min (DA58E); see also (DE57). Eβ(max) = 1.202 ± 0.005 MeV (HO50), 1.185 ± 0.025 MeV (GR54C), 1.190 ± 0.003 MeV (DA58E). The positron spectrum shows no deviation from the allowed shape; it is concluded that the Fierz coefficient in the Fermi interaction is < 11%. Log ft = 3.66 (DA57B, DA58E). The positron polarization has been studied by (BO57H, HA57G). The results indicate that the positrons are completely polarized and hence that Fermi transitions as well as G-T transitions exhibit the maximum effect of parity nonconservation.
See (NO57A).
At E(3He) = 2.54 MeV, the cross section for formation of the ground state is 5.2+2.1-1.6 mb. At E(3He) = 3.60 MeV, the differential cross section for formation of the ground state at θ = 0° is 0.73 ± 0.30 mb/sr (AJ57A).
The yields of the protons to the ground and 4.4 MeV excited states of 12C have been measured for E(3He) = 1.3 to 5 MeV. Resonances are observed at 2.0, 3.7, 4.1 and 4.6 MeV, with widths of 0.5, 0.7, 0.12 and 0.15 MeV, respectively, corresponding to 13N*(23.2, 24.5, 24.8, 25.2). Angular distributions taken at six energies in the above range tend to be more asymmetric at the higher energies (SC56F). See also (JO56A).
See 11C.
See 9B.
Measurements at Eα = 8 MeV with a proton recoil telescope and a neutron threshold detector are reported to indicate 13N states at 2.4 ± 0.3, 3.6 ± 0.3, (4.3 ± 0.3) and 5.0 ± 0.3 MeV (QU56). See also (BA57D) and 14N.
Not reported.
Two resonances for capture radiation are reported, at Ep = 0.46 and 1.70 MeV (Table 13.10 (in PDF or PS)). The resonance at Ep = 1.75 MeV observed in 12C(p, p)12C does not appear in the γ-excitation curve (SE51E). The displacement of the lower level (13N*(2.37), J = 1/2+) from its mirror in 13C*(3.09) is ascribed to the large reduced width (EH51, TH52B). The angular distribution of the ground-state radiation from the upper resonance (13N*(3.51), J = 3/2-) has the form W(θ) = 1 - 0.52cos2θ (DA51, DA51B). The capture cross section at low energy is of interest in connection with stellar energy generation. Measurements have been reported in the range Ep = 80 to 360 keV by (BA50, HA50, DE57, LA57B). At 80 keV, σ = (1.4 ± 0.4) x 10-5 μb; from 80 to 126 keV, the course of the cross section is reasonably well accounted for by extrapolation of the Ep = 0.46 MeV resonance (LA57B: see also (DE57)). From Ep = 5 to 11 MeV, the cross section for formation of 13N changes only from 2.5 to 1.8 mb; this small change strongly indicates the predominance of direct capture in this region (CO55C). According to (RE56C), however, the 90° differential cross section for formation of 13N is < 1 μb/sr at Ep = 4.8 MeV. See also (CH56C). In the range Ep = 1.2 to 2.5 MeV, reaction (b) is observed, involving a γ-transition to the 2.37 MeV state. Excitation functions at θ = 0° and 90° indicate interference between p-wave resonant capture at Ep = 1.70 MeV, with Γγ = 0.04 eV, and direct p-wave capture (WO54). The angular distributions at Ep = 1.37 and 1.58 MeV have the form W(θ) = (0.02 ± 0.02) + sin2θ (HE55).
Elastic scattering studies indicate a number of pronounced resonances in the range Ep = 0 to 6 MeV: see Table 13.11 (in PDF or PS). The first five excited states correspond in character and approximately in reduced width to those of 13C: see 12C(d, p)13C and 12C(n, n)12C. The relatively large reduced widths of the first and third (s1/2 and d5/2) excited states indicate a single-particle character (JA53B). The small and roughly equal widths of 13N*(6.4, 6.9) suggest that they may comprise a doublet, built upon 12C*(4.4) + p (RE56C: see also (BL53A, MA53H, SC56D)). Angular distribution measurements above Ep = 10 MeV generally show direct interaction effects: see 12C. Some form of resonance structure may exist near 23 MeV (KI55B). See also (KL56). The yields of 4.4 MeV gamma rays and inelastic protons from 12C*(4.4) show resonances at Ep = 5.39 and 5.93 MeV (MA53H, BR56D, LI57). Angular distributions of inelastic protons at Ep = 6.1 to 6.9 MeV do not fit direct interaction theory and suggest the effects of still higher compound nucleus levels (BR56D). Polarization studies for Ep < 6 MeV are reported by (GA56A, SO56B, WA58A): see also 12C. See also (TO55C, ER56A, NI56B, GL57; theor.) and (GO57F).
See 11C.
See 9B.
Neutron groups have been observed corresponding to excited states of 13N at 2.29 ± 0.12 (GR49A), 2.38 ± 0.05 MeV (MI53) and 3.48 ± 0.12 (GR49A), 3.74 ± 0.05 (GR57B), 3.53 ± 0.05 MeV (MI53). The angular distributions of the ground state group and the groups corresponding to the 2.37 and (3.51 ± 3.56) MeV states at Ed = 9.0 MeV are consistent with lp = 1, 0 and 2. The dimensionless reduced widths of the ground and (3.56) MeV states are respectively 0.056 and 0.19 (CA57A: see also (MI53)). (MC58D) finds that the reduced widths of the ground states of 13C and 13N are the same, 0.09 ± 0.035 (see also (BE56, CA56B, KA58D) and 12C(d, p)13C). In the range Ed = 2.8 to 3.7 MeV, a single neutron threshold is observed, at Ed = 3.09 ± 0.02 MeV, corresponding to 13N*(2.36 ± 0.02); the slow rise above threshold is attributed to p-wave neutron emission (MA55J). Polarization of neutrons has been studied for Ed = 2.5 to 3.6 MeV by (HA57C). See also (BO56L, BO56M, DE56D).
Not reported.
See also (RI50E, MA55K, BI58A) and 14N.
See (FR52E).
See 14N.
See 14N.
At Ed = 14.8 MeV, triton groups are observed corresponding to the states at 0, 2.37 and (3.51 ± 3.56) MeV. The cross section for the transition to the 2.37 MeV state is two orders of magnitude smaller than that for the ground state transition. Transitions to 13N*(2.37, 3.56) are shell-model forbidden (WA57).
Not reported.
Not reported.
See (WH58A).
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