
^{16}N (1982AJ01)(See Energy Level Diagrams for ^{16}N) GENERAL: See also (1977AJ02) and Table 16.4 [Table of Energy Levels] (in PDF or PS). Model calculations: (1979RO1J, 1980HA35). Reactions involving muons: (1977BO23, 1977ER04, 1977NA1N, 1978GU07, 1978PA1F, 1978RO1P, 1979ER07, 1979GU06, 1979GU08, 1979HO07, 1979KI1G, 1979RH1A, 1979ST1Q, 1979WU10, 1980BR1A, 1980CH03, 1980GR05, 1981EI1A). Reactions involving pions: (1977AL1W, 1977BA1Q, 1977BE2L, 1977ER04, 1977HO13, 1977SH1C, 1977SU1L, 1978FU09, 1978NA1N, 1978OH03, 1979BO21, 1979DE1W, 1979ER07, 1979KN1G, 1979NA1J, 1979PE1C, 1979SR1B, 1979TR1B, 1979WI1E, 1979WI1A, 1980BO1B, 1980BO24, 1980DE29, 1980GR05, 1980ST15, 1980WU01, 1981YA1A). Other topics: (1976LE1F, 1977AR06, 1977BA22, 1977BR03, 1977HA1L, 1978BU1B, 1978FO10, 1978GA1C, 1978GE1C, 1978HE1C, 1978KO01, 1978LE15, 1979AB04, 1979AL22, 1981GR08).
The halflife of ^{16}N is 7.13 ± 0.02 sec: see Table 16.3 (in PDF or PS) in (1971AJ02). See also (1975SA1D). From the character of the beta decay [see Table 16.21 (in PDF or PS)] it is concluded that ^{16}N_{g.s.} has J^{π} = 2^{}: see ^{16}O. The beta decay of ^{16}N*(0.12) [J^{π} = 0^{}, τ_{1/2} = 5.26 ± 0.06 μsec] to ^{16}O_{g.s.} has been studied: the βdecay rate λ_{β} = 0.43 ± 0.10 sec^{1} (1975PA01). See also (1977AK1B; applications) and (1977BO23, 1978GU07, 1979GU08, 1979KO39, 1979MU1B, 1979RH1A, 1980CH03, 1981CH1B, 1981TO1J; theor.).
The yields of t_{0} and of α_{0}, α_{1} and α_{2} have been measured for E(^{7}Li) = 4 to 14 MeV at 0°: several broad peaks are observed (1971WY01). The yields of α_{0} and α_{2} have also been studied for E(^{7}Li) = 3.3 and 5.0 to 6.2 MeV (1969SN02). The cross section for reaction (c) rises monotonically for E(^{7}Li) = 1.1 to 4 MeV (1957NO17, 1959NO40).
Angular distributions have been obtained at E(^{7}Li) = 16 MeV to ^{16}N*(3.36, 3.52, 3.96, 4.32, 4.39). The σ_{t} for ^{16}N*(3.36, 3.96, 4.32, 4.39), whose J^{π} are known, follow the 2J_{f} + 1 relation. From the σ_{t} for ^{16}N*(3.52) it follows then that J = 2 if it is a single state or J = 0 and 1 (with one of the two states having odd parity) if the group corresponds to two unresolved states (1975FO10). See also (1971AJ02).
See (1966MC05).
See (1966MC05) and (1969TH01: E_{x} = 297.6 ± 0.9 and 397.8 ± 1.0 keV).
At E_{α} = 50 MeV proton groups are reported to ^{16}N*(5.1, 5.6, 7.6, 11.4, 12.1) (1976BU21). See also (1977FO1E, 1981HA1J).
At E(^{6}Li) = 44 MeV angular distributions to ^{16}N*(3.96, 5.73, 7.65, 11.21, 11.81) are strongly forward peaked (1977MA1B; prelim.).
The cross section has been measured for 1.2 < E_{d} < 2.6 MeV. It shows some evidence of structure (1964NE09). See also (1971AJ02).
Observed resonances for n_{0}, p and d_{0} are displayed in Table 16.5 (in PDF or PS). For polarization measurements in reaction (a) see (1977AJ02). For reaction (b) see also (1977AJ02). See also ^{12}B in (1968AJ02) and ^{13}C, ^{14}C, ^{15}C and ^{15}N in (1981AJ01).
Proton groups have been observed to ^{16}N states with E_{x} < 12 MeV and angular distributions (with E(^{3}He) ≤ 15 MeV) lead to the J^{π} assignments shown in Table 16.6 (in PDF or PS).
At E_{α} = 46 MeV the angular distributions of the groups to ^{16}N*(0.30, 3.96, 5.73, 7.60) have been determined: the most strongly populated state is the (5^{+}) state ^{16}N*(5.73) (1969LU07).
Observed proton groups are displayed in Table 16.7 (in PDF or PS). Angular distributions have also been measured at E_{t} = 15 MeV to the first four states of ^{16}N: cross sections obtained by DWBA analysis using microscopic wave functions are in poor agreement with the data (1979FO01). These distributions have also been compared with those in the (^{3}He, p) reaction to analog states in ^{16}O: see reaction 38 in ^{16}O (1978FO27). τ_{m} for ^{16}N*(0.40) = 5.1 ± 0.3 psec (1977HE1D, 1977HE12). See also (1977AJ02).
At E_{α} = 65 MeV strong transitions are observed to the unresolved ground state quartet and to ^{16}N*(5.25, 6.61, 7.68) (1978JA10).
At E(^{10}B) = 100 MeV strong transitions are observed to the unresolved ground state quartet and to ^{16}N*(5.14, 6.59, 7.65) (1978HA10). For reaction (b) see (1980PR09).
The thermal cross section is 24 ± 8 μb (1973MU14).
The scattering amplitude (bound) a = 6.44 ± 0.03 fm, σ_{free} = 4.59 ± 0.05 b, σ^{spin}_{inc}(bound nucleus) < 1 mb (1979KO26). The total cross section has been measured for E_{n} = 0.4 to 32 MeV: see (1971AJ02, 1976GAYV) and (1971ZE02). Observed resonances and parameters derived from Rmatrix and phaseshift analyses of these data, angular distributions and polarization measurements are displayed in Table 16.8 (in PDF or PS) (1971ZE02, 1971DO06). See also (1977AJ02) and (1976RO16, 1977RO09, 1978RO05, 1979AB17, 1979RO04, 1980HA35; theor.).
For reaction (b) see (1976AJ04, 1978BA1M). For reaction (c) see (1978BA1M). For reactions (a) and (d) see (1977AJ02).
Levels derived from observed proton groups and γrays are listed in Table 16.9 (in PDF or PS). Gamma transitions are shown in the inset of Fig. 2: (1971PA28) report that the branchings of ^{16}N*(0.40) to ^{16}N*(0, 0.12, 0.30) are, respectively, 26.6 ± 0.6%, 73.4 ± 1.6% and ≤ 0.15%. The 0.30 → 0.12 transition is ≤ 1% (1971PA28). The mean life of ^{16}N*(0.12) is 7.58 ± 0.09 μsec (1967BE14); together with the angular distribution analyses this leads to J^{π} = 0^{} for this state. The very strong evidence for J^{π} = 2^{}, 3^{} and 1^{}, respectively, for ^{16}N*(0, 0.30, 0.40) is reviewed in (1971AJ02). See also (1977BA22, 1978PA05, 1979PA02; theor.).
See (1980PR09).
See ^{16}C.
Partial μ^{}capture rates leading to ^{16}N*(0.12, 0.40) [J^{π} = 0^{}, 1^{}] are consistent with the assumption of a large mesonic exchange effect in the time part of the weak axial current (1979GU06). See also (1981GI1C), (1978GU07; theor.) and the "GENERAL" section here.
See (1979TR1B).
See (1978NE1A, 1978NE1B; E_{n} = 60 MeV). See also (1977AJ02).
At E_{t} = 23.5 MeV ^{16}N*(0, 0.30) [J^{π} = 2^{}, 3^{}] are strongly populated relative to ^{16}N*(0.12, 0.40) [0^{}, 1^{}]. This suggests that the 2^{} and 3^{} states in ^{16}F are those that are strongly populated in the ^{16}O(^{3}He, t)^{16}F reaction [^{16}F*(0.42, 0.72)] and that the other two states in ^{16}F [^{16}F*(0, 0.20)] are 0^{} and 1^{} [the ordering within the 2^{} and 3^{}, and the 0^{} and 1^{} states, in ^{16}F is ambiguous] (1974FL06). See also ^{16}O(^{3}He, t) [reaction 4] in ^{16}F.
At E(^{11}B) = 115 MeV unresolved groups near E_{x} = 0 and 6 MeV are relatively strongly populated (1979RA10).
^{3}He groups observed in this reaction are displayed in Table 16.10 (in PDF or PS) (1978MA16). Polarization data is consistent with 1p_{1/2} for ^{16}N*(0, 0.30), with perhaps some small 1p_{3/2} admixture for ^{16}N_{g.s.}. There is no significant deviation for a pure 1p_{3/2} VAP for the groups to ^{16}N*(6.17, 6.36) [J^{π} = 4^{}, 3^{}] (1981MA1E). Comparisons of the ^{16}N states with T = 1 states in ^{16}O are discussed by (1977WA11, 1978MA16): see reaction 81 in ^{16}O and Table 16.20 (in PDF or PS). See also (1977AJ02).
At E_{p} = 43.7 MeV, the angular distribution of the ^{3}He nuclei corresponding to a state at E_{x} = 9.9 MeV fixes L = 0 and therefore J^{π} = 0^{+} for ^{16}N*(9.9): it is presumably the T = 2 analog of the ground state of ^{16}C. Some lowerlying T = 1 states were also observed (1964CE05). See also (1978FO10).
Alphaparticle groups observed in this reaction are displayed in Table 16.9 (in PDF or PS). Polarization measurements are reported at E_{dbar} = 8.5 to 11.3 MeV (1978BA43) and at 52 MeV (1981MA1W): see footnotes ^{j}, ^{k} and ^{l} in Table 16.9 (in PDF or PS). ^{16}N*(8.82, 9.8, 10.06) may be related to nearly bound virtual states of a 2s_{1/2} neutron with ^{15}N*(6.32, 7.30, 7.57) (1970BO08, 1970BO09). (1975AS02) find τ_{m} = 6.5 ± 0.5 psec for ^{16}N*(0.40) and g = 1.83 ± 0.13; M^{2} for the M1 transition to ^{16}N*(0.12) is 0.17 ± 0.02 W.u..
Angular distributions have been reported for E_{n} = 4.7 to 14.4 MeV [see (1971AJ02, 1977AJ02)] and at E_{n} = 13.9 and 15.6 MeV (1977RO06; α_{0+1+2+3}). See also ^{20}F in (1983AJ01).
