(See Energy Level Diagrams for 14N)
Astrophysical questions:(1982CA1A, 1982WO1A, 1985BR1E, 1985DW1A, 1985PR1D, 1986CH1H, 1986DO1L, 1986HA2D, 1986LA1C, 1986MA1E, 1986SM1A, 1986TR1C, 1986WO1A, 1987AL1B, 1987AR1J, 1987AR1C, 1987AU1A, 1987BO1B, 1987CU1A, 1987DW1A, 1987ME1B, 1987MU1B, 1987PR1A, 1987RA1D, 1987WA1L, 1988BA86, 1988CUZX, 1988DU1B, 1988DU1G, 1988EP1A, 1988KR1G, 1988WA1I, 1989AB1J, 1989BO1M, 1989CH1X, 1989CH1Z, 1989DE1J, 1989DU1B, 1989GU1Q, 1989GU28, 1989GU1J, 1989GU1L, 1989HO1F, 1989JI1A, 1989KA1K, 1989KE1D, 1989ME1C, 1989NO1A, 1989PR1D, 1989WY1A, 1990HA07, 1990HO1I, 1990RO1E, 1990SI1A, 1990WE1I)
Complex reactions involving 14N:(1984MA1P, 1984XI1B, 1985BE40, 1985KW03, 1985PO11, 1985RO10, 1985SH1G, 1985ST20, 1985ST1B, 1985WA22, 1986AI1A, 1986BO1B, 1986GR1A, 1986GR1B, 1986HA1B, 1986MA13, 1986MA19, 1986ME06, 1986PL02, 1986PO06, 1986SA30, 1986SH2B, 1986SH1F, 1986VA23, 1986WE1C, 1987BA38, 1987BE55, 1987BE58, 1987BO1K, 1987BU07, 1987FE1A, 1987GE1A, 1987GO17, 1987HI05, 1987JA06, 1987KO15, 1987LY04, 1987MU03, 1987NA01, 1987PA01, 1987RI03, 1987RO10, 1987SH23, 1987ST01, 1987TE1D, 1988AY03, 1988CA27, 1988GA12, 1988HA43, 1988KA1L, 1988LY1B, 1988MI28, 1988PAZS, 1988POZZ, 1988PO1F, 1988SA19, 1988SH03, 1988SI01, 1988TE03, 1988UT02, 1989BA92, 1989BR35, 1989CA15, 1989CEZZ, 1989GE11, 1989KI13, 1989MA45, 1989PO06, 1989PO07, 1989PR02, 1989SA10, 1989VO19, 1989YO02, 1989ZHZY, 1990BO04, 1990DE14, 1990GL01, 1990LE08, 1990PA01, 1990WE14, 1990YE02)
Pion capture and reactions:(1983AS01, 1984AS05, 1985BE1C, 1985KO1Y, 1985LA20, 1985RO17, 1985TU1B, 1986AR1F, 1986BE1P, 1986CE04, 1986DY02, 1986ER1A, 1986GE06, 1986KO1G, 1986LAZL, 1986PE05, 1986RA1J, 1986RO03, 1986SU18, 1987AH1A, 1987BL15, 1987BO1D, 1987BO1E, 1987DOZY, 1987GI1B, 1987GI1C, 1987GO05, 1987KA39, 1987KO1O, 1987LE1E, 1987NA04, 1987RO23, 1988GIZU, 1988KO1V, 1988MI1K, 1988OH04, 1988TI06, 1989BA63, 1989CH31, 1989DI1B, 1989DO1L, 1989GA09, 1989GE10, 1989GIZW, 1989GIZV, 1989IT04, 1989KH08, 1989NA01, 1989RI05, 1990BE24, 1990CH12, 1990CH1S, 1990DI1D, 1990ER03, 1990ER1E, 1990GH01)
Ground state of 14N:(1985AN28, 1985GO1A, 1985ZI05, 1986GL1A, 1986RO03, 1986WI04, 1987AB03, 1987KI1C, 1987VA26, 1988BI1A, 1988VA03, 1988WO04, 1988WRZZ, 1989AM01, 1989AN12, 1989GOZQ, 1989SA10, 1989WO1E, 1990BE24, 1990VA1G, 1990VA01)
< r2 >1/2 = 2.560 (11) fm (1980SC18),
Natural abundance:(99.634 ± 0.009)% (1984DE53)
The energy of the 5.83 → 5.11 γ transition is Eγ = 728.34 ± 0.10 keV. When corrected for the nuclear recoil and added to Ex = 5105.89 ± 0.10 keV, Ex = 5834.25 ± 0.14 keV for 14N*(5.83) (1981KO08) [recalculated]. For branching ratios see 14.11 (in PDF or PS). See (1981KO08) also for a general discussion of electromagnetic transitions in 14C and 14N, and comparison with theory.
Excitation functions have been measured to Eα = 26 MeV. Observed resonances are displayed in 14.12 (in PDF or PS). (1975WI04) has expanded the angular distributions of the p0 → p3 groups into Legendre polynominals and fitted the coefficients at 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. However, an R-matrix analysis by (1983CS03) suggests Jπ = 2-, 3+, 1+ for 14N*(13.69, 13.74, 13.77). (1975WI04) 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.
Excitation curves have been measured at Eα up to 27 MeV [see (1970AJ04, 1976AJ04, 1981AJ01)]. The low energy resonances are exhibited in 14.12 (in PDF or PS). At the higher energies the yield curves are fairly smooth although broad resonances in the d1 and d0 yields corresponding to 14N*(23.25), respectively have been reported as has 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 (1981AJ01). For cross sections at Eα = 29.5 MeV (reaction (a)) and 25.0 and 30.1 MeV (reaction (b)) see (1983VA28). See also 12C in (1990AJ01) and (1989VA07).
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 50.6 MeV: see (1981AJ01). Observed resonances are displayed in 14.12 (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): see (1981AJ01).
States with Ex > 10 MeV studied in this reaction at E(6Li) = 34 MeV are displayed in 14.13 (in PDF or PS) (1984CL08). In addition most of the lower-lying T = 0 states have been populated: see (1970AJ04, 1981AJ01).
At E(7Li) = 24 MeV angular distributions of the tritons to 14N*(3.95, 5.83, 6.45, 8.96, 9.13, 10.06, 10.81, 12.79 + 12.81, 13.03, 15.26) have been studied. 14N*(4.91, 5.11, 5.69, 6.20, 7.03, 7.97, 8.49, 8.98, 9.39, 11.05, 11.51, 12.42) are also populated: see (1981AJ01).
For cross sections see (1986CU02).
The capture γ-rays [reaction (a)] have been studied at E(3He) = 0.9 to 2.6 MeV (θ = 0°, 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 excitation function for reaction (b) has been measured for E(3He) = 1.5 to 18 MeV [see (1981AJ01)]. A broad peak at E(3He) = 4.15 MeV may indicate the existence of 14N*(24), Γ ≈ 1 MeV.
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. This is also true for the ground-state deuterons of reaction (d) in the same energy interval. Yield curves for reaction (e) have been measured for E(3He) = 6 to 30 MeV: see (1976AJ04). Ay measurements for t0 and t1 are reported at E(pol. 3He) = 33 MeV: see (1986AJ01). See also 13C and 13N, and 11B, 11C, 12C in (1990AJ01).
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. See also 10B in (1988AJ01).
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. 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: see (1976AJ04).
For angular distributions to Eα = 13.9 MeV see (1981AJ01). At Eα = 47.4 MeV, θ = 0°, unresolved groups are reported to Ex = 5.2, 8.6, 14.71, 16.84, 19.10, 20.52, 21.72, 22.38, 23.57 and 24.25 MeV (1988LU02). [See for comments about dominant Jπ: high-spin states are expected to be preferentially populated.] Uncertainties in Ex are ± 0.35 MeV for 15 MeV neutrons to 1.5 MeV for 30 MeV neutrons. Widths could not be determined. A state at ≈ 25 MeV was also populated [J.D. Brown, private communication]. See also 15N, (1986AJ01) and (1988CA26; astrophys.).
Resonances in the yields of neutrons and protons are displayed in 14.14 (in PDF or PS). The 0° yield of neutrons shows broad structures at Ed ≈ 7.2 and 11.5 MeV [ n0] and 8 and (10.8) MeV [n1] as well as a sharper structure at Ed ≈ 9.5 MeV: see (1986AJ01).
Polarization measurements for both reactions (a) and (b) have been made at many energies. For the earlier work see (1970AJ04, 1976AJ04, 1981AJ01, 1986AJ01). Recent studies have been reported for reaction (b) at Ed = 0.25 → 1.10 MeV (1986KO08; p0) and at Epol. d = 12 MeV (1988LA03; 13C states with Ex < 7.7 MeV; VAP, TAP), 56 MeV (1986SA2G; p0, p1; Kyy' and Ky'yy; prelim.), 2.1 GeV (1987PE19, 1989PU01; TAP; deuteron breakup), and 9.1 GeV/c (1988AB13; TAP). For the breakup at high energies see also (1984KO42, 1989AV02, 1989BE2K). For reaction (c) to 12B*(0, 4.4[u]) at Epol. d = 70 MeV see (1986MO27, 1988MO11; VAP, TAP) [see (1986MO27) for comment re lower energy measurement at 0°]. For a study of the Δ-region at Epol. d = 2 GeV see (1989EL05).
For a study of the (pol. d, pol. pX) reaction at Epol. d = 65 MeV see (1989IE01). For a report on high-energy γ-ray production see (1989NI1D). For pion production see (1986AJ01) and (1987AG1A). For total cross sections see (1986AJ01) and (1987KI1J; prelim.; 2.0 to 4.0 GeV/c). See also (1984NA1F, 1989NA1R) and (1986AI04; applied).
Reported resonances are displayed in 14.14 (in PDF or PS). For a listing of excitation function measurements see (1976AJ04). A recent study is reported by (1986HO26; Ed = 0.60 to 1.10 MeV; d0). For the earlier polarization measurements see (1976AJ04, 1981AJ01, 1986AJ01). Ay = 0.412 ± 0.011 at Epol. d = 56 MeV (θ = 47.5°), and VAP and TAP have been studied for Epol. d = 35 to 70 MeV (1985KA1A, 1986KA1Z). Studies of VAP and TAP have also been carried out at Epol. d = 56 MeV (1986MA32; d0) and 191 and 395 MeV (1986GA18; inclusive scattering; on C). At Epol. d = 400 MeV, VAP and TAP measurements are reported for the groups to 12C*(4.4, 9.7, 12.7, 18.3) (1987AR1H; prelim.). For the (d, pn) reaction at Epol. d = 56 MeV see (1989OK02).
Reported resonances are displayed in 14.14 (in PDF or PS). 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 (1971RI15, 1972SM07) 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 αt for the "allowed" groups is ≈ 1%, an order of magnitude greater than predicted by direct or multistep processes (1972SM07). An S-matrix analysis leads to the resonance parameters shown in 14.14 (in PDF or PS) (1981JO02). For polarization measurements see (1986AJ01).
Angular distributions have been measured to states below 8.7 MeV at Et = 1.12 to 1.68 MeV and at 8 MeV: see (1976AJ04).
Observed proton groups are displayed in 14.15 (in PDF or PS). Angular distributions have been measured for E(3He) to 25.3 MeV [see (1970AJ04, 1976AJ04)] and at E(pol. 3He) = 33 MeV: see (1986AJ01). For a discussion of 14N*(9.13) see (1986WA13). For work at very high energies see (1987AB1J). See also (1986SC35, 1990TO10; applied).
Angular distributions of deuterons have been studied corresponding to the T = 0 states 14N*(0, 3.95, 4.92, 5.11, 5.69, 5.83, 7.97, 8.49, 8.96, 9.13, 9.39, 10.81) [Eα = 34.5, 42, 55 MeV; not all states at all energies]. At the higher energies 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 ± 0.1 MeV: see 14.19 (in PDF or PS) in (1976AJ04), and (1981AJ01, 1986AJ01). At Eα = 50 MeV the angular distributions of the singlet deuterons exciting the T = 1 states 14N*(2.31, 8.91[u]) have been studied by (1986SA06): a state at 12.6 ± 0.3 MeV is also populated. See also (1989GA1H, 1989SH1G).
At E(6Li) = 20 MeV [see 14.19 (in PDF or PS) in (1976AJ04)] and 32 MeV [see 14.13 (in PDF or PS) here] many of the α-groups corresponding to T = 0 states with Ex < 17.2 MeV are observed. The 5+ state, 14N*(9.0), is strongly populated: see (1970AJ04). Angular distributions have been measured at E(6Li) = 2 to 33 MeV: see (1981AJ01, 1986AJ01). Inclusive α-particle spectra have been studied at E(6Li) = 156 MeV (1989JE01). See also 18F in (1987AJ02), (1987PA12) and (1986HA1E; 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. Angular distributions are reported at E(12C) = 49.0 to 93.8 MeV: see (1981AJ01, 1986AJ01).
At E(13C) = 390 MeV angular distributions have been studied to 14N*(0, 2.31, 5.8[u]) and to unresolved structures and continua. The spectra are dominated by the group to 14N*(5.8) (1987AD07, 1988VO08). See also (1989VO1D).
The low-energy capture cross section yields an extrapolated S-factor at Ep = 25 keV (c.m.), S0 = 6.0 ± 0.8 keV · b. 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: see (1970AJ04).
Following is a summary of the reasons for the assignments of Jπ; T to some of the lower resonances displayed in 14.16 (in PDF or PS): for a fuller discussion and complete references see (1970AJ04, 1976AJ04, 1981AJ01). 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; therefore, T = 1 [but 1.4% 8.06 → 2.31 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 = 5691.55 ± 0.13 keV (1981BI17). 14N*(8.49, 8.96, 9.13) correspond to anamolies in the cross section. The nature of their γ-decays [see 14.11 (in PDF or PS)] and the angular distribution leads to Jπ = 4-, 5+, 3+ [all T = 0], respectively.
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 → 6.20 and the angular correlation 8.62 → 6.20 → g.s. is consistent with Jπ = 1+, T = 0 for 14N*(6.20) [Ex = 6203.7 ± 0.6 keV]. 14N*(8.78) [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*(6.45) [see however 14.10 (in PDF or PS)] and J = 2 for 14N*(7.03). For recent studies of 14N*(9.17) see (1981BI17, 1986WA13): Ex = 9172.5 ± 0.3 keV from Eγ, Γγ0/Γγ = (79 ± 4)%, Γ [from (p, p)] = 135 ± 8 eV [135 ± 11 eV in (γ, γ)]. Other Ex determined by (1981BI17) are 2312.90 ± 0.03, 3948.2 ± 0.2, 5105.9 ± 0.3, and 6446.3 ± 0.2 keV. See also 14.11 (in PDF or PS) and 14.15 (in PDF or PS).
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, 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. 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) have been observed: these are shown in 14.16 (in PDF or PS) in the range Ep = 3.7 to 6.6 MeV. 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. Measurements of the γ0 and γ1 90° yields for Ex = 23 to 33 MeV find that the T = 2 resonances reported earlier 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. 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. A study of the 90° yield of γ0 and γ1 [and of analyzing powers] has been reported for Epol. p = 6.25 to 17.0 MeV. The γ0 results are in good agreement with those 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. At Ep = 25 MeV strong transitions are observed to two groups of states centered near Ex = 5.8 and 8.9 MeV.
For searches for short-lived neutral particles in the decay of 14N*(9.17) see (1986SA2E, 1988SA2A). See also (1985AB15), (1986RO18, 1988KI1C; applied), (1985CA41, 1987WE1C, 1988CA26, 1989BA2P, 1990MA1P; astrophysics) and (1986WE1D, 1987MC1C) and (1980HA30; theor.).
The elastic scattering has been studied for Ep = 0.14 MeV to 1 GeV: see (1981AJ01) and 13C here. For observed resonances see 14.16 (in PDF or PS). Ay measurements have been reported at Epol. p = 200 and 547 MeV [see (1986AJ01)], at 35 MeV (1986OH03; p0→3), at 71.8 MeV (1989VO05, 1990VO02; p0; and measurements of depolarization parameter, D), at 119 MeV (1988CO05; p0 → p4 and p to 13C*(7.55, 8.86, 9.5, 9.9)) and at 500 MeV (1990HO06; p0; Ay and rotation parameters). See (1990HO1L; prelim.) for measurements at Ep = 497.5 MeV on pol. 13C. The 0+ - 0- doublet at Ex ≈ 8.7 MeV has been studied by (1984AD04, 1986AD01, 1986SW1A, 1987ZEZZ, 1988ZE1B). For pion production see (1988HU06). See also (1985BL22, 1986ADZT) and (1986RA05, 1987BE1M, 1987BE1P, 1988RA08, 1989AM05, 1989BEXT, 1989GO14, 1989KU07, 1989KU14, 1989KU32, 1989RA1O, 1990DU01; theor.).
Observed resonances are displayed in 14.17 (in PDF or PS). Polarization measurements are reported at Epol. p = 35 MeV (1986OH03; Ay; n0, n1, n2+3) and 160 MeV (1984TA07, 1987RA15; Ay; DNN(0°); n0, n2+3, and n to 13N*(15.1)[u]). Forward-angle cross sections have been measured at Ep = 318 and 800 MeV (1986KI12) and at 492 and 590 MeV (1989RA09). Cross sections for 13N production have been studied for Ep = 5.2 to 30.6 MeV by (1989WA16. For the earlier work see (1986AJ01). See also 13N, (1987ALZW, 1990TA1J), (1986AI04, 1989AR1Q; applied), (1985CA41; astrophysics), (1986AL18, 1986CA1N, 1986TA1E, 1987TA22) and (1987BE1D, 1989AM02, 1989RA15; theor.).
Ay measurements have been reported at Epol. p = 13.6 to 530 MeV [see (1986AJ01)] and at 119 MeV (1987LE24; to 12C*(0, 4.4, 7.7, 9.6, 12.7, 14.1, 15.1, 16.1, 16.6, 17.8, 18.1, 18.8, 19.9, 20.3, 20.6)). For a measurement of the tensor polarization of 12C*(15.1) at Ep = 41.3 MeV see (1987CA20). For other work see (1976AJ04, 1981AJ01) and 12C in (1990AJ01). See also (1986KO1K; theor.).
Angular distributions have been reported at E(pol. 3He) = 33 MeV to 14N*(0, 2.31, 3.95, 5.11, 5.83, 8.91, 9.51) (1986DR03; also Ay). See 14.18 (in PDF or PS) here, and (1981AJ01), for the earlier work.
At E(7Li) = 34 MeV angular distributions have been studied to 14N*(0, 2.31, 3.95, 5.0[u], 5.7[u]). 14N*(7.0, 8.9, 9.5) are also populated. 14Ng.s. is dominant (1987CO16). See also (1986AJ01), (1988AL1G) and reaction 18 in 14C.
Forward-angle differential cross sections for the isobaric-analog state (IAS) [14N*(2.31)] have been measured at Eπ+ = 20 MeV (1987IR01), 35 to 80 MeV (1986UL01), 100 to 295 MeV (1983IR04) and 300 to 550 MeV (1988RO03). Angular distributions to the IAS are reported by (1986UL01, 1987IR01), See also (1985IR02, 1989LE1L) and (1989ST1H theor.).
Angular distributions, generally for the n0, n1 and n2 groups, have been measured in the range Ep = 2.45 to 45 MeV [see (1981AJ01, 1986AJ01)] and at Epol. p = 35 MeV (1990IE01) and 160 MeV (1987RA15). (1984TA07) have been measured the transverse spin-transfer coefficients [DNN(0°)] at 160 MeV for the groups to 14N*(0, 2.31 [DNN = 1], 3.95, 13.72). The main GT strength lies in the three 1+ states and their DNN values, which are consistent with 1/3, are those expected for pure L = 0 transitions (1984TA07). At Ep = 60 to 200 MeV the spectra are dominated by the neutrons to 14N*(3.95) (1987TA13). 0° differential cross sections have recently been obtained at Ep = 60 to 200 MeV (1987TA13; n0, n1, n2), 200, 300, and 450 MeV (1989AL04; n1, n2) and 492 MeV (1989RA09). See also (1989MAZP). For discussions of the Fermi and Gamow-Teller strengths see (1985WA24, 1987RA15, 1987TA13, 1989RA09). See also 15N, (1985TA23, 1989SU1J), (1988CA26, 1989KEZZ; astrophysics), (1986AL18, 1986TA1E, 1986VO1G, 1987BE25, 1987GO1V, 1987HE22, 1987RA32, 1988RO17, 1988WA1Q, 1989RA1G, 1989SU1A) and (1986PE1E, 1987LO13, 1987LO1D, 1989AM01; theor.).
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 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). Angular distributions have also been studied at E(3He) = 72 MeV (1988DE34, 1988DE47, 1989ER05; t0, t1, t2).
Angular distributions have been studied at E(6Li) = 34 and 62 MeV [see (1986AJ01)], at 93 MeV (1986BR33, 1987DE02, 1988DE47, 1989DE34; to 14N*(0, 3.95)) and at 84, 150 and 210 MeV (1987WI09, 1986AN29, 1988AN06; to 14N*(0, 2.31, 3.95)). 14N*(3.95) dominates the spectra: see e.g. (1987WI09). 14N*(5.11, 5.83, 6.20, 7.03, 8.49) are also populated (1980WH03, 1987WI09). For studies of the GT strength see (1980WH03, 1987WI09). See also (1987AU04, 1988AU1E, 1988GA1N, 1989AU1B) and (1986AJ01).
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. 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: see (1981AJ01). 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 and for a small amount of isospin T = 0 mixing near 22.5 MeV: see (1981AJ01). The cross section for the (γ, n) reaction has recently been measured from threshold to 15.5 MeV (1987FA14). See also (1988DI02).
The (γ, p0) and (γ, p2) cross sections and angular distributions have been measured in the giant resonance region. The giant dipole states [(p3/2)-1 (2s1d)] which decay by p0 emission to 13C*(3.68) appear to carry ≈ 90% of the E1 strength and do not contibute 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: see (1976AJ04). For reaction (c) see (1987IM02). For rection (d) see 14C. See also (1985FU1C) and (1985GO1A, 1986WI10, 1987HU01, 1987KI1C, 1987LU1B, 1988DU04; theor.).
A measurement of the protons from the 14N(γ, p)13C reaction and a resonant absorption measurement lead to Γγ0/Γ = 0.052 ± 0.004 for 14N*(9.17) and to Γ = 122 ± 8 eV (1989VA21). See also (1986AJ01), 14.19 (in PDF or PS), (1985BEZI, 1987BE1K) and (1986DU03; theor.).
Form factors have been determined at many energies in the range Ee = 60.7 to 300 MeV: see (1981AJ01, 1986AJ01) for the earlier references. In recent work at Ee = 80.0 to 372.6 MeV the form factors for 14N*(0, 2.31) have been determined [q = 0.80 to 3.55 fm-1] (1987HU01; see for a discussion of the wave functions for these two states): see also (1989AM01, 1989TA01). A number of other excited states of 14N have also been studied: see 14.19 (in PDF or PS). (1984BE13) have populated 14N*(12.50, 13.17, 13.71, 15.43, 15.7, 17.2, 17.8) but not the 5- states at Ex = 14.66 and 17.46 MeV which are thus presumably T = 0. (1984BE13) report that within the triplet of 5- states at 14.66, 16.91, 17.46 MeV, they can account for ≈ 60% of the isovector 5- strength but only 35% of the isoscalar strength. There is no other significant M4 strength up to Ex ≈ 28 MeV (1984BE13).
See also (1986LI1C, 1987DE43, 1987LI30, 1987RO23) and (1985CH1F, 1985CH1G, 1985GOZP, 1986DO11, 1986ER1A, 1986GO29, 1986JE1B, 1986ZE1A, 1987GO08, 1988AL1J, 1988GO1R, 1988YA10, 1990BE24, 1990GA1M; theor.).
Angular distributions of elastically and inelastically scattered neutrons are displayed in 14.23 (in PDF or PS) of (1970AJ04). Recent work is reported at En = 7.68 to 13.50 MeV (1986CH2F; prelim.; to 14N*(0, 2.31, 3.95, 4.91, 5.11, 5.69, 5.83)), 11, 14 and 17 MeV (1985TE01; n0; prelim.), 20 and 25 MeV (1985PE10; n0) and at 21.6 MeV (1990OL01; n to 14N*(0, 5.83, 7.03) as well as at Epol. n = 10, 12, 14 and 17 MeV (1986LI1M; n0; prelim.). See also (1976AJ04), (1986GEZX, 1989LI26) and (1989STZW; applied).
Angular distributions of elastically and inelastically scattered protons have been studied at many energies up to Ep = 800 MeV [see (1981AJ01, 1986AJ01)], at Epol. p = 35 MeV (1990IE01; p1) and 800 MeV (1985BL22; elastic) and at Ep = 1 GeV (1985AL16; elastic). For a display of the observed 14N states see 14.24 (in PDF or PS) in (1986AJ01). For a study of the 1.6 and 2.3 MeV γ-rays [from 14N*(2.31, 3.95)] see (1988LE08). For reaction (b) see (1989BE1P) and 13C. For reaction (c) see (1985DE17). For reaction (d) see 10B (1988AJ01). See also (1989BEXX), (1985PE10, 1987VD1A) and (1986AO1A, 1986ER1A, 1987HU01, 1987VD03, 1988VD1B, 1989AM01, 1989LO1E; theor.).
Angular distributions of elastically and inelastically scattered deuterons have been studied to Ed = 52 MeV: see 14.20 (in PDF or PS) in (1981AJ01). 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]: see (1981AJ01). See also (1986HA1E, 1986AO1A; theor.).
Angular distributions of elastically and inelastically scattered α-particles have been studied for Eα = 7.6 to 104 MeV [see 14.24 (in PDF or PS) in (1986AJ01)] and at Eα = 48.7 and 54.1 MeV (1987AB03; α0). See also 18F in (1987AJ02), (1987BU27, 1989BE1R), (1989GU28; astrophysics), (1988PA1K; applied) and (1985SH1D; theor.).
Elastic angular distributions have been measured at E(6Li) = 19.5, 32 and 36 MeV and at E(7Li) = 36 MeV: see (1981AJ01, 1986AJ01). For reaction (b) see also (1986GO1H; E(14N) = 150 MeV; prelim.). See also (1989DE1Q).
Elastic angular distributions have been measured for reaction (a) at E(10B) = 100 MeV and E(14N) = 73.9 to 93.6 MeV [see (1981AJ01, 1986AJ01)] as well as at E(14N) = 38.1, 42.0, 46.0 and 50.0 MeV (1988TA13); those for reaction (b) have been studied at E(14N) = 41, 77 and 113 MeV: see (1981AJ01). For fusion and other yield measurements see (1986AJ01). See also (1985BE1A, 1985CU1A) and (1985KO1J, 1986RO12; theor.).
Elastic and inelastic angular distributions have been studied in the range E(14N) = 21.3 to 155 MeV [see (1981AJ01)] and at 86 MeV (1988AR23). For cross sections and fusion, fragmentation and evaporation residue studies see (1981AJ01, 1986AJ01) and (1986MO13, 1987GO01, 1987ST01, 1989KI13, 1990WE14). For high-energy γ-emission see (1986ST07). For neutron emission see (1988KI06). For pion emission see (1989SUZS). For reaction (b) see (1987AR25). See also (1986GO1H, 1987VE1D, 1988HAZS, 1989AR1M), (1982BA1D, 1985BA1T; astrophys.), (1985BE1A, 1985CU1A, 1987GE1B) and (1985HU04, 1985KO1J, 1985VI09, 1986BA62, 1986HA13, 1986POZW, 1986RE14, 1987BI20, 1987RE03, 1987RE11, 1988BA37, 1988HE12, 1988PR02, 1989BL1D, 1989NI1C, 1989RO22, 1989SH05, 1990CA1S, 1990DE13, 1990GH1F, 1990PR01; theor.).
Elastic angular distributions have been studied for E(14N) = 5.0 to 20.2 MeV: see (1981AJ01). For fusion and other cross section measurements, see (1981AJ01, 1986AJ01). See also (1985BE1A, 1985CU1A, 1986ST1J, 1986ST1A, 1988BO46) and (1985KO1J, 1986RO12; theor.).
Elastic angular distributions have been studied for E(14N) = 8.1 to 155 MeV [reaction (a)]: see (1981AJ01). For fusion cross section measurements, see (1981AJ01, 1986AJ01). See also (1985BE1A, 1985CU1A) and (1985HU04, 1985KO1J; theor.). For reaction (b), see (1989HO1H; theor.).
Elastic angular distributions have been measured at E(14N) ≈ 53 MeV for reactions (a), (c) and (d) [see (1986AJ01)] and at 84 MeV (1988YA06; reaction (d); also inelastic to 28Si*(1.78)). For fusion and fragmentation studies see (1986AJ01) and (1986SH25, 1987BE55, 1987GU1M, 1987ST01, 1987YI1A, 1988SH03, 1989BR1K, 1990GOZZ). For reaction (e), see also (1988GO12). For pion production [reaction (c)], see (1986ST03). See also (1987SH1A), (1987BL1D) and (1985BL17, 1985CE11, 1985ST20, 1986OS05, 1986POZW, 1986PR01, 1988AY03, 1989BH03, 1989CH1K; theor.).
Angular distributions have been obtained at Ep = 39.8 MeV for the deuterons corresponding to 14N*(0 → 8.06, 8.62, 8.91, 8.96 + 8.98, 9.17, 9.39, 9.51, 9.70, 10.10, 10.21, 10.43, 11.06, 11.23 + 11.30, 11.39, 11.51, 11.66, 11.74 + 11.80, 11.97, 12.21 + 12.29, 12.52, 12.61, 12.80 + 12.83, 13.17 + 13.23, 13.72). Spectroscopic factors were extracted by DWBA analysis of the ln = 1 pickup angular distributions: see (1969SN04). See also (1970AJ04).
At Epol. d = 89.1 MeV (1989SA13) have investigated the level structure of 14N up to Ex = 24 MeV: see 14.21 (in PDF or PS). Above Ex = 18.6 MeV no discrete states appear. The observed summed spectroscopic strength is 88% of the shell-model sum rule. No significant l = 3 strength was seen (1989SA13).
Observed states in 14N are displayed in 14.28 (in PDF or PS) of (1976AJ04) together with the derived spectroscopic factors. Recently, angular distributions and Ay have been determined at E(3He) = 33 MeV to 14N*(0, 2.31, 3.95, 5.11, 5.83, 7.03, 9.17, 10.43, 12.5, 13.7) (1986DR03).
At Eπ+ = 116 MeV proton angular correlations, energy sharing and recoil momentum distributions have been studied to groups corresponding to 14N*(0, 3.9[u], 7.0[u], 11.0[u]). No evidence is seen for other narrow states. The upper limit for the excitiation of 14N*(2.31) [0+; T = 1] is 5% (1988SC14). See also (1990SC1O) and (1989CH04; theor.). Work at Eπ+ = 165 MeV suggests that the earlier work reports too low a cross section and underestimates the two-nucleon absorption mechanism (1990HY01). In this paper the fraction of the total absorption cross section which can be attributed to that mechanism is reported to be about 50% (1990HY01). See also (1988KY1A, 1988RO1M).
Angular distributions (reaction (a)) have been measured in the range Ep = 27 to 54.1 MeV: see (1981AJ01). 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 14Og.s.: see 17F in (1982AJ01). For cross sections for the production of γ-rays from the decay of 14N*(2.31, 5.11) at Ep = 40, 65 and 85 MeV see (1987LA11). For reaction (b) see (1986VDZY, 1987VD1A) and (1986GO28; theor.).
Angular distributions have been measured at many energies up to Ed = 40 MeV: see (1981AJ01). The yield of the isospin forbidden α1 group [to 14N*(2.31)] has been studied for Ed = 2 to 15 MeV: the intensity of the 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%. At Ed = 50 MeV, the intensity of 14N(2.31) is 0.1 - 0.2% that of 14Ng.s.. See also 18F in (1987AJ02), (1985KA1A), (1985HA38, 1986DU1K; applied) and (1986SI1D; computer).
See (1988CA26; astrophys.).