(See Energy Level Diagrams for 15N)
Astrophysical questions: (1976BO1M, 1976EP1A, 1976FI1E, 1976ME1H, 1976NO1C, 1976SP1B, 1977AU1E, 1977AU1F, 1977CA1K, 1977CL1C, 1977CO1U, 1977CO1W, 1977HA1L, 1977JO1D, 1977PR1E, 1977ST1H, 1977TR1D, 1977WA1P, 1978BU1H, 1978BU1B, 1978CL1F, 1978DW1B, 1978EN1C, 1978PO1B, 1978SN1A, 1978ST1C, 1978ST1D, 1978YA1B, 1979GU1D, 1979JA1M, 1979LA1H, 1979OL1B, 1980CA1C, 1980PE1F).
Special reactions involving 15N: (1976AB04, 1976BU16, 1976FU1J, 1976HE1H, 1976HI05, 1976LE1F, 1977AR06, 1977KO38, 1978AB08, 1978VO10, 1978CR1B, 1978GE1C, 1978HE1C, 1978KO01, 1978LE15, 1978TU06, 1978VO1A, 1979AL22, 1979GE1A, 1979HE1D, 1979SA27, 1979WU01, 1980MI01, 1980YO02).
Muon and neutrino capture and reactions: (1979ER07).
The yield of p0 and p1 (reaction (a)) for E(6Li) = 3.84 to 6.40 MeV shows some broad structure: analysis in terms of Ericson fluctuation theory gives a value of ≈ 0.4 MeV for the average level width at Ex = 28 MeV in 15N (1967SE08). The excitation functions for t0 (reaction (b)) α0, α1 and α2 (reaction (c)) show broad structures for E(6Li) = 4 to 14 MeV (1971WY01). See also 11B and 12C in (1980AJ01) and 14C. See also (1976AJ04).
At E(6Li) = 4.9 MeV, thirty proton groups are observed corresponding to 15N states with Ex < 16.8 MeV. Angular distributions have been measured for the proton groups corresponding to 15N*(5.27 + 5.30, 6.32, 7.16 + 7.30, 7.57, 8.31, 8.57, 9.05 + 9.15) (1966MC05).
The 90° differential cross section for γ0 production has been measured for Eα = 5.74 to 17.80 MeV (1977DE04) and 6 to 11.5 MeV (1978DE23; also angular distributions). Observed resonances are displayed in Table 15.6 (in PDF or PS).
Reported resonances are listed in Table 15.7 (in PDF or PS). The yield curve for 14C is dominated by two strong resonances at Eα = 1.57 and 2.64 MeV (1976DA06; CTR implications). At higher energies (to 25 MeV) the p0 excitation functions show broad features: see (1978HO08: Eα = 4.4 to 6.7 MeV) and (1976AJ04).
At E(6Li) = 34 MeV angular distributions are reported to the states with 5.3 < Ex < 16.3 MeV: this reaction appears to be less than reaction 13. The most strongly populated states are 15N*(9.2, 10.5, 10.7, 13.1, 14.8, 15.5) (1976NO01). See also (1976AJ04).
At E(7Li) = 24 and 34 MeV, angular distributions to states with 5.3 < Ex < 15.6 MeV have been measured (1976KO11, 1976NO01): 15N*(9.8, 10.5, 10.7, 15.4, 15.5) are particularly strongly populated at 34 MeV. Jπ = 9/2+, 9/2, 11/2, 9/2, 11/2, 13/2, 15/2 are suggested for 15N*(10.69, 12.56, 13.03, 13.19, 13.84, 14.11, 15.37) (1976KO11). (1976NO01) find that only 15N*(15.52) has a large cluster component corresponding to 11B + α. The γ-decay of 15N states populated in this reaction has been studied by (1979HA38): see Tables 15.4 (in PDF or PS) and 15.5 (in PDF or PS). For earlier work see (1976AJ04).
At E(11B) = 114 MeV broad peaks are observed at 15N*(5.3, 9.7, 13, 16.8, 20) (1974AN36).
Angular distributions have been measured at E(16O) = 27, 30, 32.5, 35 and 60 MeV involving 15Ng.s. + 12Cg.s., 15Ng.s. + 12C*4.4, 15N*6.32 + 12Cg.s. and 15Ng.s. + 12C*9.6 (1972SC03, 1972SC17, 1975SC35): the reaction selectively populates the two proton-hole states of 15N: 15N*(0, 6.32) [Jπ = 1/2-, 3/2-]. See also (1976AJ04) and (1976DE08, 1977WE1H; theor.).
The 90° excitation function for γ0 (reaction (a)) in the range 1.0 to 3.4 MeV shows one very strong resonance (at peak, 4.4 ± 0.5 μb/sr) corresponding to 15N*(16.7). The excitation function and the measured angular distributions were analyzed [S-matrix] (1977SC01): Table 15.8 (in PDF or PS) shows the derived parameters. Table 15.8 (in PDF or PS) also displays the structures observed in reactions (b) → (e). Polarization studies of the elastic scattering are reported at Et-bar = 15.0 and 17.0 MeV by (1978SC02). See also 11B and 12C in (1980AJ01), 14C and 14N here, and (1976AJ04).
Angular distributions have been measured for Eα = 13.4 to 42 MeV [see (1976AJ04)] and at Eα = 17.52 to 18.64 MeV (1979MO03; p0), 24 to 33 MeV (1978BU27; p3), 40 MeV (1979VA08; p1+2 and p to 15N*(10.7, 15.4)) and at 96.8 MeV (1975FA07: see Table 15.9 (in PDF or PS); reduced widths are calculated). At 97 MeV the spectrum at 10.5° is dominated by 15N*(15.37) [Jπ = 13/2+]: DWBA calculations have been carried out using a semi-microscopic three-nucleon form factor and several different sets of wave functions (1975FA07). See also (1976BU21, 1979AMZU), (1977FO1E, 1978FA1H), (1980ZE05; theor.) and 16O in (1982AJ01).
Observed 3He groups are displayed in Table 15.9 (in PDF or PS). Comparisons of the angular distributions obtained in this reaction at E(6Li) = 60.1 MeV and in the (6Li, t) reaction shows analog correspondence for the following pairs of levels: 5.27 - 5.24, 7.16 - 6.86, 7.57 - 7.28, 8.58 - 8.28, 10.80 - 10.48, 13.15(u) - 12.84, 15.49(u) - 15.05 [first listed is Ex in 15N; second in 15O] (1975BI06) [Ex are nominal; u = unresolved.]. For γ-decay measurements see Table 15.4 (in PDF or PS) (1978HA39, 1979HA38). See also (1977MA2G), (1977FO1E) and the earlier work reported in (1976AJ04).
Observed α groups are shown in Table 15.9 (in PDF or PS) (1973TS02). Angular distributions have been measured to E(7Li) = 35 MeV: see (1976AJ04). Comparison of spectra from this reaction (E(7Li) = 34.9 MeV) with those from 13C(6Li, α) (reaction 32) lead to configurations of (d)3 for 15N*(10.7, 12.57, 13.20, 15.42) and suggest that 15N*(12.57, 13.20) have lower J than 15N*(10.7, 15.5), probably J ≤ 7/2. 15N*(13.02) is shown to be p(d)2 in agreement with Jπ = 11/2- (1976HA31).
15N*(9.155) [J = 5/2] decays to 15N*(5.30) [Jπ = 1/2+] by an E2 transition; therefore its parity is positive. It has a large triton cluster parentage. This is not true of 15N*(9.152) (1978HA39). For γ-decay measurements see Table 15.4 (in PDF or PS) (1978HA39, 1979HA38). For τm measurements see Table 15.5 (in PDF or PS).
At E(10B) = 100 MeV angular distributions have been measured for 15N*(5.27, 7.57, 9.87, 10.87, 13.15, 15.72, 16.26, 17.83) and comparisons have been attempted with those to states in 15O, in the mirror reaction (1973NA09) [see however reaction 7 in 15O (1976AJ04)]. (1974AN36; E(10B) = 100 MeV), on the other hand, report population of 15N*(0, 5.24, 7.28, 9.64, 10.47, 12.89, 15.36, 15.88). 15N*(12.89, 15.36) are the most intense groups (1974AN36). For reaction (b) see (1978FR20, 1979FR05). See also (1977FO1E).
At E(19F) = 40, 60 and 68.8 MeV angular distributions have been measured for the transitions involving 15N*(0, 5.3) and various 16O states: 15N*(5.3) is very strongly excited (1972SC17). See also (1975PU02, 1977KO38).
The 90° - 95° yields of γ0 have been measured for Ed = 1 to 10 MeV: observed resonances are displayed in Table 15.10 (in PDF or PS). The γ-ray angular distributions are consistent with the emission of predominantly E1 radiation except for evidence of M1/E2 transitions in the region Ex = 20 - 21.5 MeV (1976DE32).
Excitation functions for elastically scattered deuterons have been measured in the range Ed = 0.4 to 5.7 MeV: see (1976AJ04). Polarization studies are reported at Ed = 12.5 MeV (1975ZA08; d0) and 15 MeV (1974BU06; d0) and at Ed-bar = 13 MeV (1978DA17: VAP; 13C*(0, 3.09, 3.68, 3.85)).
Observed resonances are listed in Table 15.10 (in PDF or PS). Polarization measurements have been reported at Ed = 12.1 and 15 MeV [see reaction (a), (1976AJ04)] and at Ed-bar = 13 MeV (1978DA17: VAP; 12C*(0, 4.4, 7.7)) and 29 MeV (1979CO08: VAP; 12C*(0, 4.4, 12.7, 15.1, 16.1), 12Bg.s.). See also 12B and 12C in (1980AJ01).
Observed proton groups and γ-rays are listed in Table 15.11 (in PDF or PS). Gamma ray branching ratios are displayed in Table 15.4 (in PDF or PS) and τm in Table 15.5 (in PDF or PS). Angular distributions have been measured at E(3He) = 4.37 to 5.57 MeV (1978CH19; p0) and at 20 MeV (1977PE23: to 15N*(0, 5.27 + 5.30, 6.32, 8.31, 8.57, 9.05, 9.15, 9.23, 9.76, 9.83, 9.93 [parity probably -], 10.07)). The earlier work at E(3He) = 5 MeV led to an assignment of Jπ = 1/2- for 15N*(9.22) and is consistent with J = 5/2 for 15N*(9.152) (1972ST22). The g-factor for 15N*(5.27) [Jπ = 5/2+] is +(0.9 ± 0.3) (1975FO06). See also 16O in (1982AJ01), (1976EP1A; astrophys.) and (1976AJ04).
Angular distributions have been measured at E(6Li) = 32 MeV to 15N*(0, 5.30, 6.32, 7.16, 7.30, 7.57, 8.31, 8.57, 9.15, 9.23, 9.83, 10.07, 10.70, 11.94, 13.00): the results are consistent with the previously known Jπ, with (odd) parity for 15N*(9.83) and with Jπ = 9/2- for 15N*(11.94) (1977HA30). See also (1976HA31) in reaction 19.
Observed resonances are displayed in Table 15.12 (in PDF or PS); the branching ratios are shown in Table 15.4 (in PDF or PS). In the γ0 yield for Ep = 2.8 to 30 MeV (1975HA39) find that the T = 1/2 and 3/2 components of the GDR are located near Ex = 20 and 26 MeV. Narrow anomalies are reported at Ep = 10.0 and 11.0 MeV (relative strength is not in agreement with (1973WE04)), 12.35, 13.6 and 16.4 MeV. Above the giant dipole resonance region the 90° γ0 cross section decreases smoothly with energy except for a small peak which would correspond to 15N*(37.) (1975HA39). (1976SN01; Ep-bar = 7.5 to 19 MeV) find that a good fit to the total cross section is obtained with the GDR split into peaks at Ex = 21.0 and 25.5 MeV with Γ = 6 and 2 MeV respectively. The integrated E2 cross section for Ex = 19.5 to 27.0 MeV is (6.8 ± 1.4)% of the isoscalar sum rule. The reaction thus shows no sign of a collective E2 resonance in that Ex region. This is confirmed by (1976WE07; Ep-bar = 4.0 to 16.2 MeV) who find no appreciable E2 strength concentration for Ex = 14.3 to 23.3 MeV. See also (1978WE07, 1979SN1A).
Observed resonances are listed in Table 15.12 (in PDF or PS). Polarization measurements are reported at several energies in the range Ep = 1.79 to 2.45 MeV (1977NI03) and 7.2 to 13.3 MeV (1971WO03). See (1977NI03) for a discussion of an R-matrix analysis of resonance parameters for 11.2 < Ex < 14.4 MeV.
Angular distributions have been measured for Ed = 1.3 to 6.5 MeV: see (1970AJ04) and (1975BO34, 1975BO35; 6.5 MeV; to Ex < 12.1 MeV; spectroscopic factors). See also (1976AJ04) and (1976SH13, 1977RI08; theor.).
Observed γ-rays are displayed in Table 15.13 (in PDF or PS). See also Tables 15.4 (in PDF or PS) and 15.5 (in PDF or PS). The 90° γ0 yield has been measured for En = 6.0 to 13.0 MeV. The angular distributions of γ0 are consistent with essentially pure E1 radiation in the region Ex = 16.5 to 23.0 MeV (1979WE1G; prelim.). See also (1978DU1E; applied).
Cross-section measurements are displayed in (1976GAYV). Recent measurements of σt are reported for En = 1.0 to 5.2 MeV by (1976BO17). See also (1976AJ04). Observed resonances are shown in Table 15.14 (in PDF or PS): for a discussion of the evidence leading to Jπ assignments see (1959AJ76).
Cross sections for production of γ-rays due to the decay of excited states of 14N have been measured in the range En = 4 to 20 MeV [see (1976AJ04)]. See also (1975RO30; to En = 19 MeV) and (1977DI1A; 2.0 to 20.0 MeV). See also (1973DI1A, 1978SU1E) and (1975YO1A).
For older cross-section measurements [En = 10 to 37 MeV] see Table 15.13 (in PDF or PS) of (1970AJ04) and (1976GAYV). The cross section has recently been reported for En = 14.7 to 19.0 MeV by (1978RY02). See also (1974BO1E).
The thermal cross section is 1.81 ± 0.05 b (1973MU14). Reported resonances are displayed in Table 15.14 (in PDF or PS). For cross section measurements see (1976GAYV), and (1979MO09; p0; to 7.0 MeV), (1976FE02; 14.7 MeV), (1975RO30; γ6.09, γ6.73; to 19 MeV). See also (1973DI1A, 1974SH1E, 1979RO1F) and (1974BO1E, 1976SL2A).
Observed resonances are listed in Table 15.14 (in PDF or PS). For cross-section measurements see (1976GAYV), and (1979MO09; α0, α1; 1 → 15 MeV and 4 to 15 MeV, respectively), (1978MO09; α0; 13.9 MeV) and (1977DI1A; γ4.4; to 19 MeV). See also (1973DI1A, 1975RO30, 1978SU1D) and (1976AJ04, 1976SL2A).
Proton groups corresponding to levels of 15N are listed in Table 15.15 (in PDF or PS). Angular distributions have been measured in the range Ed = 0.5 to 27 MeV [see (1959AJ76, 1970AJ04, 1976AJ04)] and at Ed-bar = 0.324 to 0.626 MeV (1976VA20; p0, p1+2, p3 → p5), Ed-bar = 2.0 and 2.2 MeV (1979US01; p5), Ed-bar = 10 MeV (1980KR01; see Table 15.15 (in PDF or PS)), Ed = 10.03 and 11.65 MeV (1979AO01; p0) and Ed-bar = 52 MeV (1977HE01; p0).
Branching ratios and multipolarities are shown in Table 15.4 (in PDF or PS); τm in Table 15.5 (in PDF or PS). The two states of 15N at Ex = 9.15 MeV are separated by 2.8 ± 0.5 keV: see (1976AJ04). See also (1977KO33), (1977RI08), (1976EP1A; astrophys.), (1978GO1R; applications) and 16O in (1982AJ01).
The d0 angular distributions have been measured at Et = 1.5 to 2.0 MeV (1964SC09).
At Eα = 56 MeV, the angular distribution of the ground state 3He particles has been measured by (1969GA11) and analyzed by DWBA: the ratio of the (α, 3He) and (α, t) cross sections at this energy is 1.50 ± 0.15.
Angular distributions to the ground state of 15N have been measured for E(14N)(c.m.) = 5.5 to 16 MeV: see (1976AJ04). Below ≈ 6.5 MeV, the tunneling theory of neutron transfer gives a good account of the data. At higher energies, nuclear absorption of the incident 14N ions occur (1965HI1A, 1966GA04). See (1976SW02) for a comparison of the nuclear reaction S-factors for this reaction and for 14N + 14N fusion.
Below Eγ = 15 MeV, the giant resonance of 15N decays entirely by ground state transitions. The total integrated cross section up to 35 MeV for transitions to excited states [14N*(2.31, 3.95, 5.11 + 5.83, 7.03), 14C*(6.09 + 6.59 + 6.90, 7.01), 12C*(4.4)] is 44 MeV · mb. The nature of the transitions is such as to indicate a very strong (1p3/2)0(1p1/2)3 component in 15Ng.s.. The presence of T = 1/2 in the main giant resonance region is indicated by the strong population of 14N*(7.03) (1976PA22).
A study at Ee = 18.8, 20.8, 25.7 and 29.7 MeV (reaction (c)) shows a "pigmy" resonance at Ex = 14.8 MeV, a shoulder at 15.6 MeV, a peak at 16.7 MeV [probably 1/2+ but 3/2+ is not ruled out], and the giant dipole resonance, which exhibits a great deal of structure, centered at 22 MeV. The data on the pigmy resonance are consistent with an admixture of ≈ 1% 3/2- (E2) or 1/2- (M1) to a predominantly 1/2+ (E1) state. The experiment shows that for 14 < Ex < 28 MeV the reaction goes predominantly via 1/2+ or 3/2+ (E1) states in 15N; the T = 3/2 strength is concentrated above 18 MeV (1975MU07) [see also (1975HA39)].
The (γ, t0) cross section (reaction (e)) at 90° decreases from a value of 30 μb/sr at 20 MeV to 5 μb/sr at 22 MeV and remains flat out to 25 MeV. Comparison of this cross section, and those of other photonuclear reactions, suggests an isospin splitting of ≈ 6 MeV with the T = 1/2 strength concentrated between 16 and 21 MeV and the T = 3/2 strength between 21 and 28 MeV. 15N*(21.9) is not observed (1979UE01). See also (1977SP06, 1978JU1A) and (1977AL32; theor.).
The r.m.s. radius of 15N is 2.580 ± 0.026 fm (1973FE13, 1975SC18). Inelastic groups are displayed in Table 15.17 (in PDF or PS). The giant resonance is split into two main peaks at Ex = 22 and 25.5 MeV with some structure around 20 MeV. Γγ0(C1) = (1.1 ± 0.3) × 103 eV (14 - 18.5 MeV), Γγ0(C2) = (12.5 ± 2.0) eV assuming the states responsible are 3/2+ and 3/2-, respectively. For Ex = 18.5 to 30 MeV, Γγ0(C1) = (1.96 ± 0.04) × 104 eV while Γγ0 < 0.1 eV for any C2 strength (1978AN12). See also (1976MA30, 1979SH1T), (1979MO19) and (1976SU07, 1977HO04, 1977SU1H; theor.).
Angular distributions of elastically scattered protons have been measured at Ep to 39.8 MeV [see (1976AJ04)] and at Ep = 5.85 MeV (1977SA1B) and 18.0 to 44.2 MeV (1980FA06, 1980FA07). See also (1976NO02, 1979MA2M), (1977BL07, 1979RO1B; theor.) and 16O in (1982AJ01).
At Eα = 40.5 MeV, a number of particle groups have been observed, and angular distributions have been measured: see Table 15.17 (in PDF or PS) of (1976AJ04) (1966HA19). B(E2)↓/e2 = 4.7 fm4 for 15N*(6.32): B(E3)↓/e2 = 60 fm6 for both 15N*(5.27, 7.57) (1966HA19). At Eα = 22, 24 and 28 MeV, the intensity of the back scattering is greatly enhanced over pure Coulomb scattering (1972OE01, 1973OE01). Angular distributions are also reported at Eα = 20.1 MeV (α0; back angles) and at 23.7 MeV (α0, α1+2, α3, groups to unresolved states and to 15N*(10.07)) (1977FE1C). (1976WO11) find Sα = 0.42 for 15Ng.s.. See also (1977KN1E), (1975GR41, 1977MA2E, 1979KN1F) and (1976CO27, 1977OH01, 1977SA19, 1979LE18; theor.).
Angular distrbutions of elastic scattering have been measured at E(15N) = 31.5, 36, 39.5 and 47 MeV (1978CO20). For fusion cross sections see (1978CO20, 1979KO20). See also (1977PH1C) and (1977BA3E; theor.).
Elastic distrbutions (reaction (a)) have been measured at E(15N) = 32.8, 47.9, 62.1 and 69.8 MeV (1980PR06; see also for fusion cross sections). An elastic distribution (reaction (b)) is reported at E(15N) = 44 MeV (1978PE13). See also (1979KA27; theor.). For reaction (c) see (1979SA27; theor.).
Over the giant resonance region in 16O, the decay takes place to the odd parity states 15N*(0, 6.32) and less strongly to the even parity states 15N*(5.27, 5.30, 8.31, 9.05) and to 15N*(9.23): see (1970HO21) and the earlier references in (1970AJ04). At Ee = 500 MeV most of the 1p hole-hole strength is concentrated in the groups to 15N*(0, 6.32). The 1s state shows up as a very wide asymmetric structure centered at Ex ≈ 41 MeV (1977MO1F, 1977BE1Q, 1979MO1G). See also (1977MA01) and 16O in (1982AJ01). See also (1979GO1V, 1979KI1H), (1976HA1Q) and (1977WA1R, 1978SC11, 1979LO03, 1979WA1G; theor.).
At Ep = 460 MeV, the summed proton spectrum shows two peaks corresponding to the knockout of p1/2 and p3/2 protons with binding energies of 12.4 and 19.0 MeV, respectively [15N*(0, 6.32)] (1966TY01). The ground state angular correlation has been studied at Ep = 45 MeV (1971EI06). See also (1976SI1A) and (1978HA36, 1979KU07, 1979MA20; theor.).
Angular distributions of 3He groups have been measured for Ed = 20 to 82 MeV (see (1976AJ04)). Recent measurements are reported at Ed = 29 MeV (1976FI01: to 15N states with Ex < 10.1 MeV; see for spectroscopic factors), at Ed-bar = 29 MeV (1978CO13: to 15N*(0, 6.32)) and 52 MeV (1977BE70: to 15N*(0, 6.32, 9.94 ± 0.02, 10.705 ± 0.01)). The spectra are dominated by transitions to 15N*(0, 6.32). A ZRDWBA analysis of the 29 MeV data leads to C2S = 2.25 and 3.25 for these two states [and to 2.37 and 3.31 for the analog states in 15O studied with the (d, t) reaction] (C2S are average of values obtained from two parameter sets) (1978CO13). The Ed-bar = 52 MeV work leads to Jπ = 3/2- for both 15N*(9.94, 10.71) (1977BE70). See also (1975FA06, 1976CH21; theor.).
Angular distributions have been measured at Et = 13 MeV (1965AJ01; α0, α1+2, α3).
Angular distributions are reported at E(14N) = 76.2 MeV and E(16O) = 95.2 MeV (1979MO14, 1977MO1A), and E(14N) = 155 MeV (1975NA15, 1975VO05). Angular distributions are also reported at E(19F) = 36 MeV involving 15Ng.s. and 20Ne*(0, 1.63) (1973GA14).
Angular distributions of α0 have been measured for Ep = 0.84 to 2.00 MeV and at several energies in the range 20.6 to 42.2 MeV [see (1976AJ04)] as well as at Ep = 125 to 850 keV (1979LO01), 296 to 549 keV (1978MA30) and 6.6 to 10.4 MeV (1979WI09). For astrophysical considerations see 19F in (1983AJ01) and (1978MA30, 1979LO01). See also (1977CO1W). For angular correlation measurements see (1976AJ04). For reaction (b) see reaction 82 in 16O (1977AJ02).
The cross section for reaction (a) to 15N*(5.27, 5.30) has been measured for Ebs = 14 to 30 MeV (1976TH1E, 1979TH05). See also (1972SH07). For reaction (c) see 19F in (78AJ03). See also (1970AJ04) and (1977SP06).
Other 15N tables not referred to in the text: