(See Energy Level Diagrams for 14N)
Astrophysical questions: (1976AU1B, 1976BO1M, 1976DI1F, 1976DW1A, 1976EP1A, 1976FI1E, 1976GI1C, 1976ME1H, 1976NO1C, 1976OS1E, 1976QU1A, 1976RO1J, 1976SI1D, 1976VA1D, 1976VI1B, 1977AU1B, 1977AU1E, 1977AU1F, 1977AU1J, 1977BE2J, 1977CA1N, 1977CA1J, 1977CA1K, 1977CL1E, 1977CL1C, 1977CO1W, 1977DE1N, 1977HA1L, 1977JO1D, 1977KI1M, 1977LA1G, 1977MA1T, 1977PR1E, 1977ST1J, 1977ST1H, 1977TR1D, 1977WA1P, 1978BO1M, 1978BU1H, 1978BU1B, 1978CL1F, 1978DE1R, 1978DI1D, 1978DW1B, 1978EN1C, 1978GL1E, 1978IB1A, 1978KA1R, 1978LA1K, 1978LU1C, 1978ME1D, 1978OR1A, 1978PO1B, 1978SN1A, 1978ST1C, 1978TO1C, 1978TR1C, 1979GU1D, 1979KA1T, 1979LA1H, 1979NO1F, 1979PE1E, 1979RA1C, 1979SA1M, 1979SW1B, 1979WE1F, 1980CA1C, 1980FR1G, 1980ME1B, 1980PE1F, 1980SP1B).
Special reactions involving 14N: (1975KO1F, 1976AB04, 1976BA08, 1976BU16, 1976CH28, 1976EG02, 1976HI05, 1976NA11, 1977AR06, 1977CO14, 1977GE08, 1977GO07, 1977KU1D, 1977NA03, 1977PR05, 1977ST1J, 1977ST1G, 1977TO1G, 1978AB08, 1978BH03, 1978BI03, 1978CR1B, 1978GE1C, 1978GR1F, 1978HE1J, 1978HE1C, 1978KO01, 1979DY01, 1979GA04, 1979GE1A, 1979GO11, 1979HA1Q, 1979HE1D, 1979KO1M, 1979SA27, 1979SA26, 1979SC08, 1979ST1D, 1980MI01).
Applied work: (1975SE1J, 1976CH1N, 1976CH1P, 1976EA1A, 1976EC1B, 1976LE1Q, 1976RA1J, 1976SI1G, 1976ST1H, 1976SU1E, 1977LE1J, 1977LO1J, 1977MA1F, 1978MU1E, 1978OX1A, 1978VA1H, 1979AN1L, 1979EN1D, 1979GR1E, 1979VA1D, 1979WI1C, 1979WI1L).
Pion capture and reactions: (1975BA1W, 1975KA1G, 1975KO25, 1975MA1M, 1976AS1B, 1976BA54, 1976BO2C, 1976EN02, 1976LI26, 1976RO14, 1977DO06, 1977GI14, 1977KO25, 1977MA1M, 1977MA35, 1977MA1F, 1977RI1H, 1977ST09, 1977VI1A, 1977WA1H, 1978BE27, 1978BO25, 1978GI05, 1978KI08, 1978KI13, 1978KW1A, 1978SH12, 1978SH16, 1978WE1H, 1979AM1B, 1979BA16, 1979BA2J, 1979DO17, 1979KI1K, 1979KL07, 1979MA2H, 1979PR1D, 1979SP1C, 1979UL1A, 1980DE10, 1980ER01, 1980FI05, 1980SI07).
Q = +0.0156 b (1978LEZA).
Excitation functions have been measured to Eα = 26 MeV. Observed resonances are displayed in Table 14.13 (in PDF or PS). (1975WI04) has expanded the angular distributions of the p0 → p3 groups into Legendre polynomials and fitted the coefficients at the resonances corresponding to 14N*(13.16, 13.24, 13.67, 13.76) obtaining Jπ = 1+, 2-, 2 or 3+, and 1, respectively, for these states. (1975WI04) also finds that a surprising proportion of states have a higher cross section for neutron than for proton emission: the fluctuations of σn/σp at low Eα suggest sizable isospin impurities in the 14N states. See also (1970AJ04, 1976AJ04).
Excitation curves have been measured at Eα up to 27 MeV [see (1970AJ04, 1976AJ04)] and (1975VA19: Eα = 15 to 25 MeV; d0, d1). The low energy resonances are exhibited in Table 14.13 (in PDF or PS). At the higher energies the yield curves are fairly smooth although (1975VA19) show broad resonances in the d1 and d0 yields corresponding to 14N*(23, 25) respectively, and at θ = 170° (1975SP04) report a sharp rise in the 15.1 MeV γ yield ≈ 1 MeV above the 12C*(15.1) + p + n threshold, a channel which is not isospin forbidden. See also (1976LE1K).
The yield of α-particles [and of 0.7 MeV γ-rays for Eα = 2.1 to 3 MeV] has been measured for Eα to 30 MeV [see (1976AJ04)] and for Eα = 30 to 50.6 MeV by (1976BE1M; α0). Observed resonances are displayed in Table 14.13 (in PDF or PS). In addition to two strong resonances in the α0 yields at Eα = 2.21 and 4.26 MeV (14N*(13.19, 14.66)), two other states (14N*(13.72, 14.25)) are required to fit the data: an R-matrix calculation leads to Jπ = 3+, 1+ [see, however, (1975WI04)], 3+ and 2- for 14N*(13.19, 13.72, 14.25, 14.66) (1973MO15). A strong resonance at Eα = 5.0 ± 0.1 MeV is reported in the reaction cross section for Eα = 4.0 to 9.0 MeV (1976GR1F; abstract): it is suggested that Jπ = 6+.
At E(6Li) = 5 MeV 14N*(0, 3.95, 4.92, 5.11, 5.69, 5.83, 6.20, 6.44, 7.03, 7.97, 8.49, 8.98, 9.12, 9.39, 9.70, 10.10, 10.43 (T = 1, weakly populated), 11.06) are populated ((1966MC05), and private communication). (1975FO01) have examined 14N*(9.13) in detail and conclude that it is a closely spaced doublet of which one member is populated in 13C(p, γ) and has been assigned Jπ = 2-, and the other member, populated here, has Jπ = 3+. This assignment is based on a DWBA analysis of the angular distributions at E(6Li) = 16.5 and 21.0 MeV which shows the contributions of several L values and, in particular, L = 0. For γ branching ratios see Table 14.12 (in PDF or PS) of (1976AJ04). See also reaction 22.
At E(7Li) = 24 MeV angular distributions of the tritons to 14N*(3.95, 5.83, 6.44, 8.96, 9.13, 10.06, 10.81, 12.79 + 12.83, 13.03, 15.26) have been studied by (1977KO27). 14N*(4.91, 5.11, 5.69, 6.20, 7.03, 7.97, 8.49, 8.98, 9.39, 11.04, 11.05, 11.52, 12.41) are also populated (1977KO27).
The capture γ-rays [reaction (a)] have been studied at E(3He) = 0.9 to 2.6 MeV (1970BL10; γ0; θ = 0° and 90°). When the barrier penetration factor has been removed a single resonance is observed at E(3He) ≈ 1.4 MeV [14N*(21.8)], Γc.m. = 0.65 MeV. The higher energy work quoted in (1976AJ04) has not been published.
The excitation function for reaction (b) has been measured for E(3He) = 1.5 to 18 MeV [see (1976AJ04)] and 5.0 to 11.5 MeV (1977DA18; n0). A broad peak at E(3He) = 4.15 MeV may indicate the existence of 14N*(24), Γ ≈ 1 MeV (1966DI04).
Yield curves for protons [reaction (c)] have been measured for E(3He) = 3.0 to 5.5 MeV (p0, p1, p1 + p2 + p3): they are rather featureless (1959HO01). This is also true for the ground state deuterons of reaction (d) in the same energy interval (1959HO01). Yield curves for reaction (e) have been measured for E(3He) = 6 to 30 MeV: see (1976AJ04). See also 13C and 13N, and 11B, 11C, 12C in (1980AJ01).
The excitation functions for α-particle groups [reaction (g)] have been measured for E(3He) = 0.9 to 5.5 MeV: see (1976AJ04). No significant resonance behavior is seen except for the α2 group which, in the 15° excitation function, exhibits a resonance at E(3He) = 4 MeV, Γ ≈ 1 MeV (1965FO06). See also 10B in (1979AJ01).
The excitation function for reaction (h) to 6Lig.s. + 8Beg.s. has been measured for E(3He) = 1.4 to 5.8 MeV: no pronounced structure is observed (1967YO02). At E(3He) = 25.20 to 26.25 MeV the excitation functions for the transitions to 8Be*(0, 16.63, 16.91, 17.64) are smooth, indicating a predominantly direct reaction mechanism (1974DE25).
At E(11B) = 114 MeV the relatively strongly populated states are 14N*(5.83, 8.96, 12.8) [Jπ = 3-, 5+, 4+] (1974AN36).
Resonances in the yields of neutrons and protons are displayed in Table 14.14 (in PDF or PS). Measurements of the yields of neutrons (to Ed = 17 MeV) and of protons (to Ed = 14.7 MeV) are listed in Tables 14.11 (in PDF or PS) (1970AJ04) and 14.16 (in PDF or PS) (1976AJ04). The yield of n0 has also been measured by (1976WA1L: Ed = 5.5 to 12.5 MeV). This preliminary work is characterized by a broad bump at Ed ≈ 7 MeV and by a somewhat sharper one at Ed ≈ 9 MeV (1976WA1L). For angular distributions see 13C, 13N. For spallation measurements see (1978AZ1E, 1978DU1B).
The vector analyzing power and the 0° transverse vector polarization transfer coefficient, Ky'y(0°) have been measured for Ed-bar = 5.7 to 9.7 MeV [n0, n1]. The values of Ky'y are large, close to the maximum value of 2/3, consistent with a model of the neutron as a simple spectator in the reaction (1976TE03). Ky'y(0°) has also been measured for 5 < Ed-bar < 12 MeV (1976WA1L; prelim.; n0, n1). Other recent measurements are those of the tensor polarization power for Ed-bar = 9 to 11 MeV (1977DR1F; p; prelim.) and the vector analyzing power at Ed-bar = 11 MeV (1976KR1B; n0, n1; prelim.). See also (1979SI07). For the earlier polarization measurements of neutrons (to Ed = 51.5 MeV) and of protons (to Ed = 51 MeV) see the listings in Table 14.12 (in PDF or PS) (1970AJ04) and 14.17 (in PDF or PS) (1976AJ04).
Reported resonances are displayed in Table 14.14 (in PDF or PS). Yield measurements of d0 up to Ed = 26.5 MeV are listed in Table 14.16 (in PDF or PS) of (1976AJ04). See also (1976BO1Q: Ed = 1.6 to 3.0 MeV). For total cross-section measurements at Ed = 1.55 and 2.89 GeV/c see (1978JA16). See also (1979DE1P).
Polarization measurements to Ed = 51 MeV are displayed in Table 14.17 (in PDF or PS) of (1976AJ04). Recent work has been carried out at Ed = 12.6 MeV (1976ZA1B; d0; VAP), Ed-bar = 29.5 MeV (1977PE07; d0; VAP, TAP) and 52 MeV (1980MA10, 1976BE1U; to 12C*(0, 4.4, 9.6)). The (d, np) processes are discussed in reaction 50 of 12C in (1980AJ01), reaction 36 in 13C and reaction 19 in 13N. See also (1976GE20). See also (1975BO58, 1977FR12, 1978HA1Q; theor.).
Reported resonances are displayed in Table 14.14 (in PDF or PS). Listings of measurements of the yields of α-groups to Ed-bar to 29.5 MeV are given in Tables 14.16 (in PDF or PS) (1976AJ04) and 14.11 (in PDF or PS) (1970AJ04).
The major interest in this reaction has been the study of the yield of the α2 group to the Jπ = 0+, isospin "forbidden" T = 1 state. In particular, the work of (1972SM07, 1971RI15) has shown that while the α0, α1 and α3 yields show only weak fluctuations, the α2 "forbidden" yield shows narrow resonances which implies that the source of the isospin mixing (at least in the region which they, and the subsequent work of (1974JO01) studied: Ed = 7.2 to 16 MeV) is due to states in the 14N compound nucleus. The ratio of the σt for the α2 group compared to the σt for the "allowed" groups is ≈ 1%, an order of magnitude greater than predicted by direct or multistep processes (1972SM07). Partial wave analyses lead to the resonance parameters shown in Table 14.14 (in PDF or PS) (1972SM07, 1974JO01). See also (1970AJ04).
Polarization measurements are reported for the α0 → α4 groups at Ed-bar = 11 to 14 MeV (1976PE08) and 20.7 and 29 MeV (1977CO17). See also (1976KU1D), (1974LO1B) and (1977TO1E, 1978IZ02, 1979SE04; theor.).
Extensive studies of p'γ and p'p correlations (the latter from 12C(3He, p')14N*(p)13Cg.s.) have led to the confirmation and determination of Jπ of many of the unbound states: see Tables 14.15 (in PDF or PS) and 14.11 (in PDF or PS): see (1970AJ04, 1976AJ04) for a fuller discussion and a listing of the relevant references. Recently (1977HE04: E(3He) = 11 to 20 MeV) have studied p'γ angular correlations involving 14N*(3.95, 5.10, 5.69, 6.21, 7.03). (1978MO27) find |g| = 0.66 ± 0.04 for 14N*(5.11): τm for 14N*(5.11, 5.83) are displayed in Table 14.12 (in PDF or PS). See also (1978MO1N). See also 15O, (1966YO1A, 1979HA1M), (1974LO1B) and (1976EP1A; astrophys.).
Angular distributions of deuterons corresponding to T = 0 states in 14N have been measured at Eα = 42 MeV: see Table 14.19 (in PDF or PS) in (1976AJ04), and (1970AJ04) for a listing of the references. At Eα = 55 MeV, d0 and d1 angular distributions have been studied by (1976VA07). The deuteron spectrum is dominated by very strong groups corresponding to the (d5/2)2, Jπ = 5+ state at 8.96 MeV, and to a state at 15.1 MeV: see (1976AJ04). See also (1976BU21).
At E(6Li) = 20 MeV, α groups corresponding to most of the T = 0 states with Ex < 12.7 MeV are reported: see Table 14.19 (in PDF or PS) in (1976AJ04). The spectrum is dominated by the α-group corresponding to the 5+ state at 9.0 MeV (1968ME10). Angular distributions have also been measured for E(6Li) = 2 to 33 MeV [see (1970AJ04, 1976AJ04)] and at E(6Li) = 10.5 to 13.75 and 20 MeV (1975SO1E, 1978SO01: α0, α1, α2) and E(pol. 6Li) = 20 MeV (1978MA13, 1979MA1T: analyzing power, all known T = 0 states with Ex < 10.9 MeV). For the yield of the isospin "forbidden" group, α1, see 18F in (1978AJ03, 1983AJ01). See also (1978AR01) and (1977WE08, 1978ME20; theor.).
This reaction has been studied at E(12C) = 114 MeV: the spectrum is dominated by 14N*(8.96)[Jπ = 5+] but there is substantial population also of 14N*(5.83) [3-] and of a state at Ex = 11.2 MeV (1974AN36). Angular distributions are reported at E(12C) = 58 to 64.5 MeV (1979CL06) and at 93.8 MeV (1979FU04).
Observed resonances are displayed in Table 14.16 (in PDF or PS). The decay schemes of various levels of 14N, as derived from the γ-spectra in this and other reactions, are exhibited in Table 14.11 (in PDF or PS). For τm see Table 14.12 (in PDF or PS) and (1977BI07, 1980AN1E).
The low-energy capture cross section yields an extrapolated S-factor at Ep = 25 keV (c.m.), S0 = 6.0 ± 0.8 keV · b (1960HE14). See also (1970AJ04). The capture cross section rises from (7.7 ± 1.8) × 10-10 b at Ep = 100 keV to (9.8 ± 1.2) × 10-9 b at Ep = 140 keV (1961HE02).
Following is a summary of the reasons for the assignments of Jπ; T to some of the lower resonances displayed in Table 14.16 (in PDF or PS): for a fuller discussion and complete references see (1970AJ04, 1976AJ04) and see Table 14.11 (in PDF or PS). 14N*(7.97): angular distribution of the γ-rays is consistent with Jπ = 2-. 14N*(8.06): width of resonance, isotropy of γ-rays show lp = 0: Jπ = 1- from 13C(p, p); E1 transition to g.s. is uninhibited, e.g., T = 1 [but 1.4% 8.06 → 2.3 transition [Ex = 2312.6 ± 0.3 keV] shows T = 0 admixture: α2 = 0.046]. The strong transition 8.06 → 5.69 [3.5%] permits either E1 or M1, ΔT = 1. Since 5.69 → 2.31 is seen 14N*(5.69) cannot have Jπ = 0+, and 2+ is excluded by the strength of the 8.62 → 5.69 transition. It is then Jπ = 1-; T = 0 [the isospin mixing α2 = 0.09]; Ex = 5690.5 ± 1.5 keV. 14N*(8.49, 8.96, 9.12) correspond to anomalies in the cross section. The nature of their γ-decays [see Table 14.11 (in PDF or PS)] and the angular distribution leads to Jπ; T = 4-; 0, 5+; 0, 3+; 0, respectively [see (1978KE01) for a recent study of 14N*(9.13)].
14N*(8.62) [Jπ = 0+ from 13C(p, p)] shows strong transitions to 14N*(0, 3.95, 5.69): T = 1. The strength of the 8.62 → 3.95 decay shows it is dipole and therefore J = 1 for 14N*(3.95) [Ex = 3947.6 ± 0.4 keV]. The strength of the transition 8.62 → 6.21 and the angular correlation 8.62 → 6.21 → g.s. is consistent with Jπ = 1+, T = 0 for 14N*(6.20) [Ex = 6203.7 ± 0.6 keV]. 14N*(8.79) [Jπ = 0- from 13C(p, p)] has a large Γγ consistent with E1 and T = 1. 14N*(9.17): angular correlation and angular distribution measurements indicate Jπ = 2+ for that state, 3- for 14N*(6.44) [see, however, Table 14.10 (in PDF or PS)] and J = 2 for 14N*(7.03).
The angular distribution of the γ-rays from 10.23 → 2.31 is consistent with Jπ = 1+ for 14N*(10.23): T = 0 from M2(M1) [see, however, Table 14.10 (in PDF or PS)]. The γ0 angular distribution is consistent with J = 2 for 14N*(10.43): the similar decay characteristics of this state and of 14N*(9.17) suggest that they are both Jπ = 2+, T = 1.
Below Ep = 5.5 MeV only γ0 can be observed in the capture radiation. (1971RI13) have observed a number of resonances in the γ0 yield and in the yield of the ground state γ-rays from 13C*(3.09, 3.68, 3.85): these are shown in Table 14.16 (in PDF or PS) in the range Ep = 3.7 to 6.6 MeV [see reaction 25 in (1970AJ04) for the earlier work]. Angular distributions and measurements of Γγ0 lead to the Jπ values shown. Above Ep = 7 MeV the γ0 yield shows broad structure and the giant dipole resonance at Ex = 22.5 and 23.0 MeV (1971RI13). Measurements by (1975PA18) of the γ0 and γ1 90° yields for Ex = 23 to 33 MeV find that the T = 2 resonances reported by (1971RI13) at Ex = 23.7 and 24.2 MeV do not exist and that there is no evidence for the T = 2 GDR between Ex = 25 and 29 MeV (1975PA18). The 90° yields of γ-rays to T = 0 states (4.9 < Ex < 5.9 MeV) and to T = 1 states (8.0 < Ex < 9.5 MeV) have been measured from Ex = 23 and 26 MeV, respectively, to Ex = 33 MeV (1975PA18). A recent study of the 90° yield of γ0 and γ1 [and of analyzing powers] has been reported for Ep-bar = 6.25 to 17.0 MeV by (1980TU01). The γ0 results are in good agreement with those of (1974BA37) in the inverse reaction [14N(γ, p)13C]. Broad structures are observed at Ep ≈ 8, 13, 14, 15 and 16.5 MeV. The γ1 results indicate that the T = 0 strength is spread out fairly uniformly between Ex = 13 and 23 MeV (1980TU01). At Ep = 25 MeV strong transitions are observed to two groups of states centered near Ex = 5.8 and 8.9 MeV (1980MA1E).
The elastic scattering has been studied for Ep = 0.14 MeV to 11 MeV: see (1970AJ04, 1976AJ04). For observed resonances see Table 14.16 (in PDF or PS); for angular distributions see 13C. The yields of p0 at eight angles (and the analyzing power) have been measured for Ep-bar = 9.1 to 18.4 MeV. A phase shift analysis implies the existence of resonances with Jπ = 1-, 2- and 3+ in the vicinity of Ep ≈ 15 MeV. The 1- and 2- resonances have widths of ≈ 3 - 4 MeV and have a total Γp/Γ value of 0.1. The correlation between these resonances and the GDR is not clear. There is no indication of the T = 2 states previously reported in reaction 30 (1978WE13). For other polarization measurements see (1976AJ04) and (1976TR1C). See also (1978DW1A; astrophys.).
The yield of neutrons has been measured from threshold to Ep = 13.7 MeV: see (1970AJ04). Observed resonances are displayed in Table 14.17 (in PDF or PS). The ratio of the reaction cross section at Ep = 22.8 MeV to the n0 yield is 1.06 ± 0.07: thus there is little competition of γ-rays from excited states of 13N with neutron emission making this a convenient fast neutron calibration source (1975LI11). The 0° polarization transfer coefficients have been measured for Ep-bar = 7.9 to 14.6 MeV (1976LI08). For other polarization measurements see (1965WA02; n0; Ep = 6.9 to 12.3 MeV) and (1979CL1C; 6 MeV). See also (1979BY1C), (1974LO1B, 1976WA1B, 1979BY1B) and 13N.
Analyzing power measurements for 12C*(0, 12.71, 15.11, 16.11) have been measured at Ep-bar = 65 MeV (1979HO1H) and those for 12C*(0, 4.4) are reported at Ep-bar = 200 MeV (1979CA1A). See also (1976AJ04), 12C in (1980AJ01) and (1980MC1C, 1980WH1A).
At Ep = 49.6 MeV polarization measurements have been carried out for the tritons and 3He ions to the mirror groups 11B*(0, 2.12, 4.45, 5.02, 6.74, 12.91) and 11C*(0, 2.00, 4.32, 4.80, 6.48, 12.50) (1974MA12). See also (1976AJ04) and 11B, 11C in (1980AJ01).
Excitation functions have been measured from Ep = 5.5 (α0), 6.0 (α1), 7.0 (α2), 8.0 (α3), 10 (α4), 11 (α to 10B*(5.11)) to 18 MeV. Total cross sections have also been obtained for the production of 6Li, 9Be and 10B: the latter shows a great deal of structure. The consequences for astrophysical problems are discussed by (1975OB01). The analyzing power for the α0 group has been measured at Ep-bar = 65 MeV by (1980KA03). See also 10B in (1979AJ01).
Observed neutron groups are displayed in Table 14.18 (in PDF or PS). Angular distributions have been reported at many energies up to Ed = 12 MeV: see (1970AJ04) and Table 14.18 (in PDF or PS). Comparisons of relative spectroscopic factors obtained in this reaction and in reaction 35 are shown in Table 14.23 (in PDF or PS) of (1976AJ04): it appears that Srel for 14N*(2.31) [T = 1] is smaller in this reaction than in the (3He, d) reaction although simple DWBA calculations would suggest that the factors would be the same in both proton pickup reactions. The τ · T terms appear to be energy dependent: see Table 14.23 (in PDF or PS) (1976AJ04). See also 15N and (1976FOZW).
Angular distributions have been studied at E(3He) = 13 to 17 MeV [see (1976AJ04) and Table 14.18 (in PDF or PS)]. At E(3He) = 13 MeV the angular distributions of deuterons and singlet deuterons to 14N*(0, 2.31, 3.95) have been investigated by (1976JA14): the relative spectroscopic factors for these three states are 1.0, 1.50, 0.43 for deuterons and 1.0, 1.57, 0.41 for singlet deuterons. Spectroscopic factors for these and other states of 14N observed in this reaction and in reaction 34 are displayed in Table 14.23 (in PDF or PS) of (1976AJ04). At E(3He) = 43.6 MeV 14N*(8.91, 9.51) are strongly populated while 14N*(8.49, 9.13, 9.39) are weakly excited. The d5/2 transfer to T = 0 states is concentrated in the transitions to 14N*(5.11, 5.83) (1980HA1E). See also (1979MA2K; theor.).
At E(7Li) = 34 MeV, angular distributions have been obtained for the transitions to 14N*(0, 2.31, 3.95) (1973SC26).
Angular distributions have been obtained for the n0, n1 and n2 groups in the range Ep = 6 to 14 MeV [see (1976AJ04)] and at Ep = 2.45 MeV (1977NI03; n0) and 35 MeV (1979DO14; n0, n2). DWBA analysis of the latter results favors the inclusion of an isovector tensor interaction in the transition to 14Ng.s. (1979DO14). See also 15N.
At E(3He) = 44.8 MeV, triton groups are observed corresponding to all known levels of 14N with Ex < 7.1 MeV. Triton groups were also seen to unresolved states with Ex = 8.0 → 9.5 MeV, to 14N*(10.43) and to excited states with Ex = 12.49 ± 0.04, 12.83 ± 0.05 and 13.70 ± 0.04 MeV. Angular distributions were obtained for nine of the triton groups and analyzed using a local two-body interaction with an arbitrary spin-isospin exchange mixture. Dominant L = 0 transitions are found to 14N*(2.31, 3.95, 13.7), L = 1 to 14N*(5.11), L = 2 to 14N*(0, 7.03, 10.43) and L = 3 to 14N*(5.83) (1969BA06). See also reaction 50.
Angular distributions have been studied at E(6Li) = 62 MeV for the transitions to 14N*(0, 3.95, 6.20, 7.03): the L = 0 transition to 14N*(3.95) carries at least 90% of the GT strength (1976GO25). For reactions (b) and (c) see (1980NA14).
The total absorption over the range Eγ = 9 to 31 MeV is dominated by a single peak at 22.5 MeV [estimated σ ≈ 29 mb, Γ ≈ 2 - 3 MeV] and appreciable strength extending beyond 30 MeV. The cross section cannot be accounted for solely by the (γ, n) and (γ, p0) processes: particle unstable excited states of 13C, 13N are involved (1969BE92). The combined (γ, n) and (γ, pn) cross section begins to rise rapidly above 18 MeV, reaches its maximum value of 15 mb at 23.3 MeV and exhibits structure at about 19, 20.5 and 26 MeV. The main peak (Γ ≈ 3.5 MeV: see (1970AJ04)) at 23.3 MeV appears to be split into two absorption levels (1970BE54, 1975BE60, 1975BE1F, 1976BE1H: monoenergetic photons) and (1980JU02). Maxima reported in other experiments and "breaks" in the (γ, n) activation curve are listed in (1970AJ04). Most of the photon absorption in the giant resonance region forms Jπ = 2- states in 14N which decay by d-wave neutron emission to 13Ng.s.. Some evidence is found for the existence of Jπ = 0- strength at the peak of the giant resonance. Some evidence exists for a small amount of isospin T = 0 mixing near 22.5 MeV (1980JU02).
The (γ, p0) and (γ, p2) cross sections and angular distributions have been measured in the giant resonance region by (1972CA34, 1974BA37). The authors infer that the giant dipole states [(p3/2)-1(2s1d)] which decay by p0 emission to 13C*(3.68) carry ≈ 90% of the E1 strength and do not contribute substantially to the (γ, p0) process which is populated by (p1/2)-1(2s1d) giant dipole states. Above Eγ = 22 MeV d-wave emission from 2- states appears to dominate the (γ, p0) cross section (1972CA34, 1974BA37). See also reaction 30.
The r.m.s. radius of 14N is 2.54 ± 0.02 fm: see (1976AJ04). Form factors have been determined at Ee = 60.7 to 122.0 MeV for 14N*(2.31, 3.95, 4.92, 5.11, 5.69, 5.83): the reduced transition probabilities for these states, in single-particle units, are, respectively, 0.065 ± 0.020, 1.70 ± 0.14, (1.1 ± 0.5) × 10-7, 4.1 ± 1.0, (3.8 ± 2.1) × 10-8 and 6.1 ± 1.3 (1974EN01). E.K. Warburton (private communication) calculates 8.7 ± 0.9 fsec for the τm of 14N*(3.95), on the basis of (1974EN01), the branching ratios of Table 14.11 (in PDF or PS), and the δ(E2/M1) of (1967OL02). Inelastic scattering (at θ = 180°) gives evidence for the excitation of states with Ex = 8.91 to 16.11 MeV: see Table 14.19 (in PDF or PS). See also Table 14.11 (in PDF or PS).
Angular distributions of elastically and inelastically scattered neutrons are displayed in Table 14.23 (in PDF or PS) of (1970AJ04). See also (1975BE1Y, 1978BE2B). Observed γ-rays are shown in Table 14.25 (in PDF or PS) of (1976AJ04). See also (1979SO1B; applied).
Angular distributions of elastically and inelastically scattered protons have been studied at a number of energies up to Ep = 155 MeV: see Tables 14.23 (in PDF or PS) in (1970AJ04) and 14.26 (in PDF or PS) in (1976AJ04) and (1977SA1B; p0; Ep = 5.85 MeV), (1979AO02; p0, p1; 21 MeV; pol.), (1980FO05; p0, p1, p2 and see Table 14.20 (in PDF or PS); 29.8, 36.6 and 40.0 MeV), (1980FA07; p0; 35.2 MeV), (1980CO05; p0, p1, p2; 122 MeV) and (1980MO01; p0; 144 MeV).
(1980FO05) have analyzed angular distributions to 14N*(2.31) with a microscopic model DWA which included contributions from the knock-on exchange amplitude and from central, tensor and spin-orbit forces. The first were fairly satisfactory. The extracted strengths of the tensor force were 20 - 75% larger than estimates based on the one-pion-exchange potential (1980FO05). See also (1976AJ04).
Angular distributions of elastically and inelastically scattered deuterons have been studied for Ed = 52 MeV: see Table 14.23 (in PDF or PS) in (1970AJ04), (1976AJ04), (1980KR01; d0; Ed-bar = 10 MeV), and (1976AO01, 1979AO01; d0, d1, d2; Ed = 10.0, 11.7, 14.8, 17.9 MeV). Inelastic groups are displayed in Table 14.20 (in PDF or PS). The deuteron group to the 0+, T = 1 state 14N*(2.31) is isospin forbidden: its cross section is 1 - 2 orders of magnitude less than that to 14N*(3.95) [Jπ; T = 1+; 0]. It is summarized for Ed = 6 to 20 MeV by (1979AO01) who find that the observed isospin violation is well accounted for by a direct multistep reaction mechanism which assumes that there is isospin mixing in the intermediate channels. See also (1976AJ04), 16O in (1977AJ02, 1982AJ01) and (1977IZ01, 1977IZ1B, 1978MA34; theor.).
At E(3He) = 44.6 MeV, twelve 3He groups are reported corresponding to states in 14N: see Table 14.20 (in PDF or PS) (1969BA06). The angular distributions were analyzed using a local two-body interaction with an arbitrary spin-isospin exchange mixture. A comparison of the cross sections of the reactions 14N(3He, t)14Og.s., 14N(3He, 3He')14N*(2.31) and 14C(3He, t)14N(0) [which all correspond to transitions between identical initial and final states] shows that they are roughly equal, as would be expected from charge independence, once detailed-balance, isospin coupling and phase-space corrections have been applied (1969BA06).
Angular distributions of elastically and inelastically scattered α-particles have been measured for Eα = 7.6 to 104 MeV: see Table 14.23 (in PDF or PS) in (1970AJ04) and (1976AJ04), (1974CH1T, 1976CH24; α1; Eα = 7.6 to 16.9 MeV), (1977EN01; α0; 19.8 to 23.1 MeV) and (1976FE12; α0, α2→4, α5+6, α7+8, α9, α10; 23.7 MeV). Table 14.20 (in PDF or PS) displays the observed α-groups. Generally the intensity of the α1 group is weak: see (1976CH24) and 18F in (1978AJ03, 1983AJ01). See also (1976YO02). (1976WO11) find Sα = 0.75 for 14Ng.s.. See also (1977KN1E), (1976HA1Q, 1977MA2E, 1979KN1F), (1979RA1C; astrophys.) and (1977DM1A; theor.).
See 9Be in (1974AJ01).
Elastic angular distributions (reaction (a)) have been measured at E(10B) = 100 MeV (1975NA15) and E(14N) = 73.9 and 93.6 MeV (1977MO1A, 1979MO14). The elastic distributions (reaction (b)) have been studied at E(14N) = 41, 77 and 113 MeV (1971LI11). For fusion cross sections see (1977HI01, 1978KO1J, 1978WU1C, 1980OR1C). See also (1978TA1B).
Elastic angular distributions have been measured in the range E(14N) = 21.3 to 155 MeV: see (1976AJ04). More recently studies are reported at E(14N) = 37, 47 and 58.3 MeV (1978CO20), 53 MeV (1976ZE04) and 78.8 MeV (1977MO1A, 1979MO14). At E(14N) = 155 MeV the selective population of certain 14N states is observed and angular distributions are reported for the transitions to 14N*(0, 8.96, 12.7) (1975NA11).
For fusion cross section measurements see (1976ST12, 1977SW02, 1979GO09, 1979GO11, 1979KO20, 1980WI09) and (1976AJ04). See also (1978DA1E, 1978HA1F), (1976LE1F, 1978TS04, 1979GO1R, 1979NA1G, 1980TA1B), (1978RO1D; astrophys.) and (1976AM01, 1977BA3E, 1977MA11, 1978AV1A, 1978CU1C, 1978CU1E, 1978CU06, 1978FR1N, 1978HO13, 1978KA14, 1978VA1A, 1979MO1J, 1979NA03, 1980LE11, 1980LO02, 1980VA03; theor.).
Elastic angular distributions have been studied for E(14N) = 4.99 to 20.22 MeV (1969JA15). For fusion cross section measurements see (1976ST12, 1976SW02). See also (1976AJ04), (1978RO1D; astrophys.) and (1976RU1B, 1978AV1A, 1979HU1B; theor.).
Elastic angular distributions have been measured for E(14N) = 8.08 to 155 MeV: see (1976AJ04). Recent work is reported at E(14N) = 76.2 MeV (1977MO1A, 1979MO14) and 155 MeV (1977TO02: see also 16O in (1982AJ01)). For fusion cross section measurements see (1976ST12, 1977SW02, 1977VO08). See also (1976AJ04) and (1978AV1A, 1978VA1A; theor.).
The elastic scattering has been studied at E(14N) = 19.5 MeV (1977KU06).
For reactions (a, b, c) see (1977TH1G). For reactions (b, c) see (1971KO11: E(14N) = 65, 84 and 88 MeV). For reaction (c) see (1977EC04: E(14N) = 27, 30 and 33 MeV). For reaction (d) see (1978PE13: E(14N) = 39 MeV). See also (1977SC1G, 1980TA1B) and (1979KA27; theor.).
Angular distributions have been obtained for the deuterons corresponding to 14N*(0 → 8.06, 8.62, 8.91, 8.96 + 8.98, 9.17 → 10.43, 10.81, 11.05, 11.24 + 11.29, 11.36 → 11.66, 11.75, 11.95, 12.20, 12.50, 12.61, 12.79 + 12.82, 13.17 + 13.24, 13.71 + 13.72) (1969SN04: Ep = 39.8 MeV). Spectroscopic factors were extracted by DWBA analysis of the ln = 1 pickup angular distributions (1969SN04). See also (1976AJ04).
At E(15N) = 30, 32 and 45 MeV the angular distributions involving 14N*(0, 2.31) have been studied: they are symmetric about 90° for the transition to the T = 1 analog state 14N*(2.31) (1975GA17, 1976GA37).
At Eπ- = 230 MeV, γ-rays from the decay of 14N*(2.31, 3.95, 5.11, 5.83) are observed (1974LI15).
Angular distributions have been measured in the range Ep = 27 to 54.1 MeV: see (1976AJ04) and at Ep = 27.0 to 30.7 MeV (1978GO04; to 14N*(2.31)). A number of comparisons have been made of the ratio of (p, 3He) to the T = 1 state at 2.31 MeV and of (p, t) to the analog ground state of 14O: see e.g. (1978GO04). See also 17F in (1982AJ01) and (1976DA1K).
Angular distributions have been measured at many energies up to Ed = 40 MeV: see Table 14.25 in (in PDF or PS) (1970AJ04), (1976AJ04) and (1973CA30; α0; 0.98 → 1.97 MeV), (1976LU1A; α0, α2; 16 MeV) and (1976VA07: α to 14N*(0, 3.95, 7.03, 11.04; 40 MeV). Analysis with a one-step ZRDWBA is reported by (1976VA07) And S values are derived: 14N*(11.04) probably has Jπ = 3+.
The yield of the isospin forbidden α1 group [to 14N*(2.31)] has been studied for Ed = 2 to 15 MeV by (1969JO09, 1973JO13): the intensity of the isospin group is strongly dependent on Ed and on the angle of observation. The α1 reaction appears to proceed almost exclusively by a compound nuclear process and its study leads to the determination of a large number of 18F states: the average isospin impurity in 18F for 10 ≤ Ex ≤ 20 MeV is 3 - 10% (1973JO13). At Ed = 50 MeV, the intensity of 14N*(2.31) is 0.1 - 0.2% that of 14Ng.s. (1975FA06). See also 18F in (1978AJ03, 1983AJ01) and (1976PE08, 1978RI05).
Measurements on the absolute cross sections of this reaction [Ed = 3.6 to 5.3 MeV] and its inverse [ 14N(α, d)16O] are consistent with the principle of detailed balance. An upper limit of 0.2% is assigned to the time-reversal non-invariant part of the reaction amplitudes (1971TH03). See also (1978HI1E, 1978PI1D; applications).
At Eα = 42 MeV the transitions involving (14Ng.s. and 6Li*(0, 3.56)), (14N*(2.31) + 6Lig.s.) and (14N*(3.95) + 6Lig.s.) have been studied by (1972RU03).