(See Energy Level Diagrams for 14N)
Collective and deformed models: (1972LA12).
Astrophysical questions: (1972CL1A, 1973AR1E, 1973AU1B, 1973AU1D, 1973AU1C, 1973BO1R, 1973CA1B, 1973CO1B, 1973IB1B, 1973MI1D, 1973RA1D, 1973SA1J, 1973SC1T, 1973SM1A, 1973TA1E, 1973TA1D, 1973TR1B, 1974BE1R, 1974SN1B, 1974WI1F, 1975AU1D, 1975CO1Q, 1975DW1A, 1975EN1A, 1975GO1Y, 1975IB1A, 1975JA1F, 1975KA1L, 1975KE1A, 1975NO1D, 1975PE1E, 1975PR1B, 1975RA1M, 1975RY1A, 1975SC1H, 1975SH1N, 1975SN1A, 1975TR1A, 1975UL1A).
Pion capture and reactions (See also reaction 60.): (1969BA1L, 1969GO1C, 1969MA1C, 1970BA44, 1970BA1E, 1970DO04, 1970KO26, 1970NE1F, 1971AM1A, 1971FA09, 1971KO23, 1971MA38, 1971MA1T, 1971MA2A, 1972AG01, 1972FA14, 1972HU1A, 1972KO31, 1972SW1A, 1972YO1C, 1973AG05, 1973AG06, 1973AR1B, 1973BA2G, 1973BU1B, 1973CH20, 1973EI01, 1973GR1F, 1973KA19, 1973KA1D, 1973NY04, 1973ST1K, 1974HU14, 1974KO07, 1974LE25, 1974LI15, 1974NE18, 1974ST1G, 1974TA18, 1974ZA05, 1975AR02, 1975BA52, 1975DE1D, 1975EI1B, 1975VE05, 1976JA04).
Other topics: (1968JO1C, 1970BO1M, 1970CO1H, 1970FO1B, 1970FR13, 1971BO1F, 1971HS05, 1971JA13, 1971MC15, 1972CA37, 1972LA12, 1972LE1L, 1972WA1F, 1973CL09, 1973CO16, 1973GO1H, 1973IG02, 1973KE1C, 1973KU03, 1973MA48, 1973PA1F, 1973PO1D, 1973RO1R, 1973RO1Q, 1973SH14, 1973SI21, 1974BO22, 1974CA1H, 1974DU11, 1974FA1A, 1974MU13, 1974SI04, 1974VA24, 1974ZU1A, 1975CA1N, 1975KU01, 1976MA04, 1976PA03).
= +0.40376077 ± 0.00000006 (1974SHYR);
rrms = 2.55 ± 0.03 fm (1974DU02).
Mass of 14N: 14.003 074 001 (11) amu (1975SM02).
In reaction (a) Eγ = 1631.3 ± 1.3 [3.95 → 2.31], 4913.8 ± 3.0 [4.92 → g.s.], 3883.0 ± 1.9 [6.20 → 2.31] and 6443.7 ± 1.8 keV [6.44 → g.s.] have been observed [transitions shown in brackets]. The τm of 14N*(6.44) is 620 ± 80 fsec [see also Table 14.13 (in PDF or PS)] (1969TH01). For reaction (b) see (1957NO17).
Recent measurements have been carried out at Eα = 1.0 to 5.0 MeV (1973VA25: n0, n1, n2+3) and at 2.0 to 7.0 MeV (1975WI04: n0). Observed resonances in these and in previous experiments are displayed in Table 14.14 (in PDF or PS). See also reaction 3.
Excitation functions have been measured to Eα = 26 MeV: see (1970AJ04) for a listing of the earlier references and (1975WI04: Eα = 2.0 to 10.7 MeV (p0), to 7.5 MeV (p1) and to 8 MeV (p2, p3); see also reaction 2). Observed resonances are displayed in Table 14.14 (in PDF or PS). (1975WI04) has expanded the angular distributions of the p0 → 3 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 (1975WI04).
Excitation curves have been measured for Eα up to 27 MeV: see (1970AJ04) for the earlier references and (1975SP04: Eα = 18 to 27 MeV; yields of 12.7 and 15.1 MeV γ). The low-energy resonances (Ed < 2.2 MeV) are exhibited in Table 14.14 (in PDF or PS). At the higher energies the yield curves are fairly smooth (see (1967AL16, 1975SP04)), although (1975SP04) report a sharp rise in the 15.1 MeV γ-yield ≈ 1 MeV above the 12C*(15.1) + p + n threshold, a reaction which is not isospin forbidden.
The yield of 0.72 MeV γ-rays has been measured for Eα = 2.1 to 3.5 MeV by (1969GA01). Excitation functions for elastically scattered α-particles have been measured for Eα = 2.0 to 4.3 MeV (1973MO15) and for 5 to 30 MeV (1972DA04). 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-, respectively for 14N*(13.19, 13.72, 14.25, 14.66) (1973MO15). For reaction (b) see (1974JE1A).
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. See also reaction 19. Branching ratios for the γ-decay of 14N states are displayed in Table 14.12 (in PDF or PS) (1966CA07). See also reaction 1 (1969TH01).
The capture γ-rays (reaction (a)) have been studied at E(3He) = 0.9 to 2.6 MeV (1970BL10: γ0; θ = 0° and 90°) and 1.5 to 5.8 MeV (γ0) and 2.0 to 5.8 MeV (γ1) (1973MA1W: 90°). When the barrier penetration factor has been removed the low-energy work shows a single resonance at E(3He) ≈ 1.4 MeV (14N*(21.8)), Γc.m. = 0.65 MeV (1970BL10). (1973MA1W: prelim. results) report two broad resonances at Ex = 23.4 and 25.0 MeV in the γ0 yield and at 24.0 MeV in the γ1 yield.
The excitation function at 0° in the range E(3He) = 1.5 to 5.6 MeV for n0 (reaction (b)) shows a broad peak at E(3He) = 4.15 MeV which may indicate the existence of a 14N state at Ex ≈ 24.0 MeV, Γ ≈ 1 MeV (1966DI04). The excitation function for reaction (b) has also been measured for E(3He) = 6 to 18 MeV (1967HA20).
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 18 MeV (1967HA20) and 10 to 30 MeV (1965BR42). See also 13C and 13N. For reactions (d, e, f) see 12C, 11C and 11B in (1975AJ02).
The excitation functions for α-particle groups (reaction (g)) have been measured for E(3He) = 0.9 to 2.15 MeV (1966LO15: α0 → α4) and 2.2 to 5.5 MeV (1965FO06: α0 → α3). 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 (1974AJ01).
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).
Angular distributions have been measured for Eα to 13.9 MeV [see (1970AJ04) for the earlier references], Eα = 3.7 to 7.9 MeV (1975VA06: n0, n1, n2) and at Eα = 12.6 to 14.8 MeV (1972CI01, 1973CI02: n0).
At E(11B) = 114 MeV the relatively strongly populated states are 14N*(5.83, 8.96, 12.8) [Jπ = 3-, 5+ and 4+, respectively] (1974AN36).
At Ed = 1.5 MeV the capture cross section is < 1 μb (1955AL16). The yield of γ0 is nearly flat from Ed = 9 to 11.7 MeV and then exhibits broad resonance structures at Ed = 12.10 and ≈ 12.8 MeV, with Γ = 0.5 ± 0.1 and 1.5 - 2 MeV, respectively [14N*(20.6, 21.2)]. The γ1 and γ2 yields have also been measured [1972DI1B: prelim. results].
Resonances in the yields of neutrons and protons are displayed in Table 14.15 (in PDF or PS). Recent measurements of the yields of these particles are listed in Table 14.16 (in PDF or PS). For angular distributions of neutrons see 13N. See also (1971MU18, 1973BI1G), (1971DU1B; theor.) and (1972LU1B, 1973WE19, 1975LE1K; applied work). For angular distributions of protons see 13C. See also (1971PU01, 1973BE25) and (1971DU1B, 1974ST05, 1975GR12, 1975MO1L; theor.). For spallation measurements see (1971BA70, 1971JA02, 1975FU01).
Polarization measurements are summarized in Table 14.17 (in PDF or PS) [and in Table 14.12 (in PDF or PS) (1970AJ04)]. The polarization transfer coefficient has been measured for Ed = 6 to 14 MeV for (n-bar)0 and (n-bar)1. The (n-bar)0 dependence shows some influence from the compound nucleus (1974LI1K). See also (1975TE1A). For neutron polarization studies see also (1971TH1E, 1975KA26), (1971WA1D) and (1974BO51, 1974BO53, 1975BO1W; theor.). For proton polarization studies see also (1971GO1E, 1971HA1R) and (HA70P, 1970PE1B, 1972GO27, 1972KO30, 1972SE09, 1974BO52, 1974SA11, 1974SA20, 1975SE07; theor.).
Reported resonances are displayed in Table 14.15 (in PDF or PS). Recent measurements of yields of d0 are listed in Table 14.16 (in PDF or PS). For a discussion of the relative yields of 12C*(12.7, 15.1) see 12C in (1975AJ02). See also (1970VE06, 1971PU01, 1971ZA04, 1975JA1A) and (1969IW1A, 1969KO1B, 1970SO11, 1974IN07, 1974ST05, 1975GU10; theor.). The (d, np) processes are discussed in reaction 38 of 13C and in reaction 21 of 13N.
The cross section rises from ≈ 0.1 mb at Ed = 16 MeV to ≈ 10 mb at 20 MeV (1955WI43).
Reported resonances are displayed in Table 14.15 (in PDF or PS). Recent measurements of the yields of α-groups are listed in Table 14.16 (in PDF or PS) [see also Table 14.11 (in PDF or PS) in (1970AJ04)]. For angular distributions see 10B in (1974AJ01).
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 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 14.15 (in PDF or PS) (1972SM07, 1974JO01). For an earlier discussion of these problems see (1970AJ04). See also (1970WE03).
Angular distributions have been measured at Et = 1.12 to 1.68 MeV (1971MA46: n0, n1, n2) and at 8 MeV (1972CO01: to 14N states with Ex < 8.7 MeV). In the latter experiment L-assignments are suggested (1972CO01). For τm measurements see Table 14.13 (in PDF or PS) (1968AL12).
Many proton groups have been observed: see Table 14.18 (in PDF or PS). Angular distributions have been measured at many energies up to E(3He) = 25.3 MeV: see (1970AJ04) for a listing of the earlier work and (1969SC1G: 2.22 - 3.60 MeV; p0, p1, p2), (1970CL1D: 3.0 to 4.05 MeV; p0, p1, p2), (1971DU03: 11.95 MeV; to states shown in Table 14.18 (in PDF or PS)) and (1972BR60: 13.3 MeV; to states with Ex < 8.7 MeV). The reaction mechanism involves the compound nucleus, at least for E(3He) <12 MeV: see (1973HE09, 1973SO04) and 15O.
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 Table 14.18 (in PDF or PS) and (1972NO08, 1974NO01, 1974NO1G)] and of Γγ/Γ [see Table 14.12 (in PDF or PS) and (1972BA56, 1972NO08)]. Table 14.12 (in PDF or PS) also displays branching ratios and radiative widths studied earlier. These studies led to Jπ = 0- or 1- for 14N*(4.92), Jπ = 2- for 14N*(5.11), odd parity for 14N*(5.83), even parity for 14N*(6.20, 6.44), J = 2 for 14N*(7.03): see (1970AJ04) for a fuller discussion and a listing of the relevant references. For τm measurements see Table 14.13 (in PDF or PS) (1970AJ04, 1973HA40). (1973BEVW) find 0.5 ≤ |g| ≤ 0.85 for the 3- state 14N*(5.83). See also (1970CA28), (1970AN1D) and (1970LK1A, 1973LI15, 1974GR39, 1974NE18; theor.).
Angular distributions of deuterons corresponding to T = 0 states in 14N have been measured at Eα = 42 to 55 MeV: see Table 14.19 (in PDF or PS) and (1970AJ04) for a listing of the references. 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 (1962HA40, 1966RI04). See also (1974VAZK, 1975VA1H), (1970AN1D) and (1971BU1K; theor.).
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). The spectrum is dominated by the α-group corresponding to the 5+ state at 9.0 MeV (1968ME10). The α1 group to the 0+; T = 1 state at 2.31 MeV state has an intensity (< 3% of α0) which decreases sharply from E(6Li) = 4 to 5.5 MeV, while the intensities of the α0 and α2 groups increase rapidly (1965CA06). Angular distributions of α-particles have been reported for E(6Li) = 2.0 to 20 MeV: see (1970AJ04) for the earlier references, (1970JO09, 1970JO1D: 5.6 to 14.0 MeV; α0, α2, α3 + α4) and (1973WH03, 1975WH03: 33 MeV; α to 14N*(0, 3.95, 4.92, 5.11, 5.69, 5.83, 6.20, 6.44)). At that energy the reaction proceeds primarily by direct interaction (1973WH03); multistep mechanisms may be very important (1975WH03). For τm measurements see Table 14.13 (in PDF or PS). For angular correlation measurements see (1974NO1G). See also (1971LA1B) and (1970OG1A, 1973OG1A).
At E(11B) = 114 MeV the spectrum is dominated by groups to the 5+ state at Ex = 8.96 MeV and to one or more of the states at 12.8 MeV, presumably the 4+ one (1974AN36, 1975PO10). See also (1972SC1L, 1973SC1J). The angular distribution of the group to 14N*(8.96) is a smoothly varying, exponential function of angle (1975PO10): see the analyses by (1965SA07, 1975PO10). See also (1970AN1D, 1970LK1A; 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). See also (1971SC1F, 1972SC1L, 1972SC21).
See (1968RO1D; theor.).
Observed resonances are displayed in Table 14.20 (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 14.12 (in PDF or PS) [see (1970AJ04) for the earlier references and see (1972RE10)]. For the τm of bound 14N states see Table 14.13 (in PDF or PS) (1971BI03, 1972RE10).
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) and (1971BA1A, 1972CA1N, 1973CL1E, 1973TR1E; astrophys. considerations). 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 14.20 (in PDF or PS): for a fuller discussion and complete references see (1970AJ04) and see Table 14.12 (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 (1971BI03)] shows T = 0 admixture: α2 = 0.046 (1972RE10)]. The strong transition 8.06 → 5.69 [3.5% (1972RE10)] 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 (1972RE10)]; Ex = 5690.5 ± 1.5 keV (1971BI03). 14N*(8.49, 8.96, 9.13) correspond to anomalies in the cross section. The nature of their γ-decays [see Table 14.12 (in PDF or PS)] and the angular distribution leads to Jπ = 4-, 5+ and 2-; T = 0, 0 and 0, respectively (1965DE19). However, work by (1975FO01) in 10B(6Li, d) shows that 14N*(9.13) is a doublet: the state populated in reaction 6 has Jπ = 3+. The structure at Ep = 1.70 MeV will therefore have to be reanalyzed.
14N*(8.62) [Jπ = 0+ from 13C(p, p)] shows strong transitions to 14N*(0, 3.95, 5.69): T = 1 (1959WA16). The strength of the 8.62 → 3.95 decay shows it is dipole and therefore J = 1 for 14N*(3.95) (1959WA04) [Ex = 3947.6 ± 0.4 keV (1971BI03)]. 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 (1971BI03)]. 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 14.11 (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) (1963RO17) [see, however, Table 14.11 (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 (1964RO03).
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 14.20 (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 show that the Jπ = 1-; T = 0 giant dipole resonance is concentrated between Ex = 15 and 23 MeV, 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 for Ex = 23 and 26 MeV, respectively, to Ex = 33 MeV; the former is quite constant at ≈ 4 μb/sr, the latter slowly rises to a value of ≈ 2 μb/sr: by comparison the γ1 yield is ≈ 1 μb/sr (1975PA18). See also (1970SI1E, 1973BE1R), (1973SU1E) and (1975VE01; theor.).
The elastic scattering has been studied for Ep = 0.14 to 11 MeV (see (1970AJ04) for a listing of the older work) and at Ep = 4.6 to 5.3 MeV (1974GM01: also p1 → p3). For observed resonances see Table 14.20 (in PDF or PS); for angular distributions see 13C. Polarization measurements for the p0 group have been carried out at 7, 14.5 and 32.9 MeV (see (1970AJ04)) and at Ep = 30.4 MeV (1972GR02; also for p1). For spallation measurements see (1973RA37).
The yield of neutrons has been measured from threshold to Ep = 13.7 MeV: see (1970AJ04). Observed resonances are displayed in Table 14.21 (in PDF or PS) (1959GI47, 1961DA09). 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). Polarization measurements are reported for Ep = 6.9 to 12.3 MeV (1965WA02: n0) and 7 to 15 MeV (1974LI1J). See also 13N and (1971GE12; theor.).
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). Integrated cross sections for populating the first four states in 11B and 11C have been measured at several energies in the range Ep = 26.8 to 43.1 MeV (1975MI01). See also 11B and 11C in (1975AJ02).
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).
Observed neutron groups are displayed in Table 14.22 (in PDF or PS). Angular distributions have been reported at many energies up to Ed = 12 MeV: see (1970AJ04) for the earlier references and (1973BO10: Ed = 4.5, 5.0, 5.5 MeV; to states shown in Table 14.22 (in PDF or PS)), (1975BO35: Ed = 6.5 MeV; to states in Table 14.22 (in PDF or PS)). Comparison of relative spectroscopic factors obtained in this reaction and in reaction 32 are shown in Table 14.23 (in PDF or PS): 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 appears to be energy dependent: see Table 14.23 (in PDF or PS) (1968CO24).
Observed γ-rays attributed to transitions in 14N are shown in Table 14.20 (in PDF or PS) of (1970AJ04): see Table 14.12 (in PDF or PS) here for a general review of radiative decays in 14N. The angular correlation of internal pairs conclusively establish the parities of 14N*(4.92, 5.11, 5.69) as odd (1964WA05). For τm measurements see Table 14.13 (in PDF or PS) (1974RU1B). See also (1972RE1C) and 15N.
Angular distributions have been studied at E(3He) = 13 and 17 MeV (1966SI02: d0, d1, d2) and 15 MeV (1966HO15, 1969HO23, 1971FO05: see Table 14.22 (in PDF or PS)). Relative spectroscopic factors are displayed in Table 14.23 (in PDF or PS) and compared with those from 13C(d, n)14N. See also (1967SP09) and (1970BO1K, 1971DZ07; theor.).
Angular distributions have been measured at Eα = 27 MeV for the α-groups to 14N*(0, 2.31, 3.95, 4.92, 5.11): relative spectroscopic factors are 1.0, 0.2, 0.3, 4.4, 5.5 (1974KE06). See also (1974DM01; 23.2, 23.7, 25.3 MeV; t0). [The earlier work at Eα = 46 MeV (see (1970AJ04)) has not been published.]
At E(7Li) = 34 MeV, angular distributions have been obtained for the transitions to 14N*(0, 2.31, 3.95) (1973SC26).
This reaction has been studied at E(11B) = 113.5 MeV (1967PO13) and 114 MeV (1974AN36). The relative population of the observed 14N states in dependent upon whether 10Beg.s. or 10Be*3.37 is involved: in all cases the cross section is greater if the 2+ state in 10Be is populated. Difficulties are encountered in separating the two sets of 14N states: see (1974AN36).
Neutron thresholds have been observed at Ep = 671.5 ± 0.5 and 3149.6 ± 1.1 keV (1956SA06) and at Ep = 4910 ± 8 keV (1960BA34) corresponding to the ground state of 14N and to excited states at 2311.9 ± 1.2 keV and 3.952 ± 0.008 MeV. Angular distributions and polarizations of the neutrons corresponding to 14N*(0, 2.31, 3.95) have been obtained at Ep = 6 to 14 MeV (1967WO05) and 7.2 to 13.3 MeV (1971WO03), respectively. The angular distributions for the ground state transition require a tensor interaction: the results are consistent with a tensor strength which is not energy dependent. The polarization measurements for the 1+ states do not clearly favor a tensor component in the effective two-body force (1967WO05, 1971WO03). See also 15N and (1969SC1H, 1972AU1A; theor.).
At E(3He) = 44.8 MeV, triton groups are observed corresponding to all the 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 47 and (1969SC1H; theor.). Angular distributions have been studied for reaction (b) for the transitions to 14N*(0, 3.95) [L = 2 and 0, respectively]: 14N*(3.95) carries at least 95% of the GT strength (1976GOZX).
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: monoenergetic photons). Maxima reported in other experiments and "breaks" in the (γ, n) activation curve are listed in (1970AJ04). See also (1968KA38, 1971FR11, 1971KA70).
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). For reaction (d) see (1970SH06, 1972GE11) and 13C. For reactions (d, e, f, g) see (1970AJ04). See also (1972BU1J, 1973DI1C, 1975BR1F) and (1969ER1A, 1971AN08, 1972GO23, 1973KI05; theor.).
Absorption measurements have led to the determination of τm (see Table 14.13 (in PDF or PS)) and of Γγ (see Tables 14.12 (in PDF or PS) and 14.24 (in PDF or PS)): see the references in (1970AJ04) and the newer work by (1974RAZD, 1975RA22). (1966SW01) find Ex = 7029 ± 6 keV for 14N*(7.03): the angular distribution of the γ-rays is consistent with J = 2.
The r.m.s. radius of 14N is given as 2.540 ± 0.020 fm (1973FE13, 1975SC18). See also (1971BE25: 2.493 ± 0.033 fm), (1970DA20: 2.64 fm), (1970AJ04) and (1969BE21, 1970BR1C, 1973TH1B). 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). Inelastic scattering (at θ = 180°) gives evidence for the excitation of 14N*(8.91, 9.17, 10.43): the Γγ0 are given in Table 14.24 (in PDF or PS) (1962ED02, 1963BA19, 1968CL05). In addition (1968CL05) report the excitation of a state with Ex = 11.01 ± 0.07 MeV. Partial Γγ for cascade transitions of 14N*(9.17, 10.43) are shown in Table 14.12 (in PDF or PS) (1968CL05). See also (1970AJ04), (1970BR1C, 1972THZF, 1974DE1E) and (1971BA2T, 1973GA19, 1974PE08; theor.).
Angular distributions of elastically and inelastically scattered neutrons are displayed in Table 14.23 (in PDF or PS) of (1970AJ04). See also (1974HO1E) and (1971MI12; theor.). Observed γ-rays are shown in Table 14.25 (in PDF or PS) (1969DI1B, 1971NY03, 1972NY02). See also (1970DI1A, 1972NI05).
Angular distributions of elastically and inelastically scattered protons have been measured and analyzed at a number of energies up to Ep = 155 MeV: see Tables 14.26 (in PDF or PS) here and 14.23 (in PDF or PS) in (1970AJ04).
Compound nucleus effects are appreciable below Ep = 15 MeV (1973HA54). The inclusion of a tensor term is necessary in the analysis of the distribution of the p1 group (to 14N*(2.31) [Jπ = 0+; T = 1]): see (1970CR03, 1973AU1E, 1973HA54). See also 15O and (1971ES1A). Observed inelastic proton groups are shown in Table 14.27 (in PDF or PS). See also (1969SC1H, 1970SA06, 1971MC15, 1972AU1A, 1973KA04, 1974OD01; theor.).
Reaction (b) at Ep = 19 MeV proceeds at least in part through an intermediate state in 14N at Ex ≈ 11.2 MeV (1965DE21). See also (1970WE09, 1970WE1J) in 13C, (1971LO25) and (1972JA1C; theor.). For reaction (c) see (1970AJ04).
Angular distributions of elastically and inelastically scattered deuterons have been obtained for Ed up to 52 MeV: see Table 14.23 (in PDF or PS) in (1970AJ04) and (1967FL10: Ed = 2.01 to 5.50 MeV; d0), (1970DU04: Ed = 5.47 (d1) and 6.37 (d2) to 10.16 MeV), (1974JA25: Ed = 10.02, 12.02 MeV: d0, very accurate, at a few angles) and (1974BU06: Ed = 15 MeV; d0). Inelastic deuteron groups are discussed in Table 14.27 (in PDF or PS). The deuteron group to the 0+; T = 1 state 14N*(2.31) is isospin forbidden: its intensity is 1 - 3% of the deuteron group to 14N*(3.95) for Ed = 7.1 to 10.2 MeV (1970DU04). The deuteron group to 14N*(8.06) [T = 1] is not observed: see Table 14.27 (in PDF or PS). See also (1970AJ04), 16O in (1971AJ02, 1977AJ02), (1970PI1A) and (1970ME25, 1971SI24, 1972DM01, 1972FO07, 1973FA1J, 1975GU10; theor.).
Angular distributions of elastically and inelastically scattered 3He ions have been measured at E(3He) up to 44.6 MeV: see Table 14.23 (in PDF or PS) in (1970AJ04) and (1970KN01: 4.5, 7.0 MeV; elastic).
At E(3He) = 44.6 MeV, twelve 3He groups are reported corresponding to states in 14N: see Table 14.27 (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). See also (1973FA1J; theor.).
Angular distributions of elastically and inelastically scattered α-particles have been measured for Eα = 11 to 104 MeV: see Table 14.23 (in PDF or PS) in (1970AJ04) for the earlier references and (1969FE10, 1970AG08: Eα = 19.8 - 23.1 MeV; α0), (1970GA25, 1971GA44: 21.7 MeV; α0, α2, α3+4, α5+6, α7+8, α9), (1972KU19: 26.6 MeV; α0), (1972LO08: 29.98 MeV; α0) and (1970HA1G: 104 MeV; α0). See also (1972OE01, 1974YOZO). See Table 14.27 (in PDF or PS) for the observed α-groups. Generally the intensity of the α1 group is weak, typically a few percent of the α0 or α2 groups: see (1959AJ76, 1966HA19). See also (1970CH1D).
Reduced transition probabilities are reported by (1966HA19): B(E2)(↓)/e2 = 6.5 and 3.3 fm4, respectively for 14N*(3.95, 7.03); B(E3)(↓)/e2 = 40 and 60 fm6, respectively for 14N*(5.11, 5.83). See also (1970AJ04) and 18F in (1972AJ02, 1978AJ03). See also (1974HA1C) and (1971MU1H, 1972DM01, 1972RA34, 1973FA1J; theor.).
See 9Be in (1974AJ01).
The elastic angular distribution has been measured at E(10B) = 100 MeV (1975NA15). For reaction (a) see also (1970IS1A). The elastic scattering angular distributions (reaction (b)) have been studied at E(14N) = 41, 77 and 113 MeV (1971LI11).
Elastic angular distributions have been measured at E(14N) = 21.3 MeV (1971VO01), 22.5 MeV (1969HE06), 65, 84 and 88 MeV (1971KO11, 1974KO38, 1975KO06), 78 MeV (1970VO02: and 12C*(4.4)), 118 MeV (1974AN36: and 12C*(4.4)), and 155 MeV (1974BI1E, 1975NA11, 1975NA15: and various 12C states). See also (1975ZE1C) and (1975MO23, 1975RA33, 1975VO1B; theor.). 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).
Elastic angular distributions have been studied for E(14N) = 4.99 to 20.22 MeV (1969JA15). For yield measurements see (1969JA15, 1973GO01, 1973RE13, 1973ST1L, 1974ST1N). See also (1973ST1A) and (1972PA31, 1973KA46, 1973PA1L, 1973PA1M, 1973SC1K, 1974VE05; theor.).
Elastic angular distributions have been measured for E(14N) = 8.08 to 18.05 MeV (1969JA15), 25 MeV (1971BO1U), 79 MeV (1976MO03) and 155 MeV (1975NA15). For yield measurements see (1969JA15, 1970SI09, 1973GO01, 1974ST1N). See also (1973KA46, 1974BA40, 1975MO23, 1975VO1B; theor.).
The decay proceeds almost entirely to the Jπ = 0+; T = 1 state of 14N at 2.31 MeV: see 14O. Measurement of the γ-ray energy from the decay of 14N*(2.31) leads to Ex = 2312.87 ± 0.10 keV (1968FR08), 2312.89 ± 0.10 keV (1967CH19). See also reaction 1 in 14O.
Angular distributions have been obtained for the deuterons corresponding to 14N*(0, 2.31, 3.95) (1961BE12: Ep = 18.6 MeV) and 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, 1969SN1B: Ep = 39.8 MeV). Spectroscopic factors were extracted by DWBA analysis of the ln = 1 pickup angular distributions. Γ = 210 ± 30 keV for 14N*(13.71). Weak deuteron groups to 14N states at Ex = 6.70, 7.40 and 7.60 MeV are reported [see, however, Table 14.11 (in PDF or PS)] (1969SN04). See also (1972PA1A).
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).
Angular distributions have been measured at Ep = 27 MeV (1973IN05: to 14N*(2.31)), 32.2, 36.6, 43.5 MeV (1975MI01: to 14N*(0, 2.31, 3.95)), 39.8 MeV (1973HO10: to 14N*(0, 2.31, 3.95)); L = 0 + 2, 0, 0 + 2, respectively), 43.7 and 54.1 MeV (1964CE02, 1970HA23, 1971FL04, 1974MA12: to 14N*(0, 2.31, 3.95, 5.11, 7.03, 9.17, 11.05); some with pol. p [also observed 14N*(10.43, 12.50)] and 49.5 MeV (1970NE1B, 1970NE17: pol. p to 14N*(0, 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 reaction 10 in 14O. See also (1969SC1F, 1972HA1X, 1974AD1B), (1974ST16; theor.) and 17F in (1977AJ02).
Angular distributions of α-particles have been measured at many energies up to Ed = 40 MeV: see Table 14.25 (in PDF or PS) in (1970AJ04) for the earlier measurements and (1971GR2B: 0.9 - 2.0 MeV; α0), (1970CA1C: 1.0 - 2.0 MeV; α0), (1973JO13: 2 to 14 MeV; α0, α1), (1971TH03: 4.405, 4.578, 4.710 MeV; α0), (1969AL13: 10.6 to 12.6 MeV; α0), (1971JA04: 14.6, 15.0, 15.8 MeV; α1) and (1974VAZK, 1975VA1H: 40 MeV; α0, α2). Alpha groups have been seen corresponding to most known states of 14N with Ex ≤ 11.5 MeV (1968JO07: Ed = 5 to 9 MeV) and (1974VAZK) observe 14N*(11.05).
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). For further discussions see (1969DE29, 1971JA04) and (1970AJ04).
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).
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).
See (1972KU1H; theor.).