(See Energy Level Diagrams for 16N)
The half-life of 16N is 7.13 ± 0.02 sec: see 16.3 (in PDF or PS) in (1971AJ02). From the unique first-forbidden character of the β decay [see 16.25 (in PDF or PS) and (1984WA07)], 16N must have Jπ = 2-: see 16O, reaction 39. See also (1985HE08, 1988BA15).
The β-decay of 16N*(0.12) [Jπ = 0-] has been measured (1983GA18, 1985HA22); adopted value: λβ = 0.489 ± 0.020 sec-1 (1985HE08). The relationship of this rate to that for 16O(μ-, ν)16N(0-) [see reaction 18] and the fact that the large values of these rates support the prediction (1978GU05, 1978GU07, 1978KU1A) of a large (≈ 60%) enhancement over the impulse approximation (e.g., εmec = 1.60) has been the subject of a great deal of theoretical study, see, e.g. (1981TO16, 1986KI05, 1986TO1A, 1988WA1E, 1990HA35). The work of (1990HA35, 1992WA1L) is a culmination of present knowledge on the determination and interpretation of εmec. See also (1992TO04). A branching ratio R(0- → 1-)/(0- → 0+) = 0.09 ± 0.02 has been reported (1988CH30), implying log ft = 4.25 ± 0.10 for the 0- → 1- transition to the 16O 7.12-MeV level.
Gamma rays with Eγ = 120.42 ± 0.12, 298.22 ± 0.08 and 276.85± 0.10 keV from the ground state decays of 16N*(0.12, 0.30) and the decay of the state at 397.27 ± 0.10 keV to the first excited state have been studied. τm for 16N*(0.30, 0.40) are, respectively, 133 ± 4 and 6.60 ± 0.48 psec. See (1986AJ04). Cross section measurements for 7Li + 11B at E(c.m.) = 1.45 - 6.10 MeV have been reported (1990DA03).
At incident 7Li energies of 40 MeV, neutron yields at 0° for reactions (a) and (b) are 50 to 70 times smaller than for 40 MeV deuteron-induced reactions on 9Be (1987SC11). For reactions (c, d, e) see (1982AJ01).
Cross sections were measured for charateristic 16N gamma rays for incident 9Be energies Ec.m. = 1.4 - 3.4 MeV. The n, p and all other two-particle emission channels are enhanced by a factor of 2 - 3 relative to predictions of DWBA calculations (1988LA25).
16N spectra were measured for incident 16O energies of 900 MeV/nucleon. Transitions to the low-lying GDR, the quasi-elastic, and the Δ-regions were observed (1987EL14).
Differential cross sections measured (1986AN30) at Eα = 118 MeV were analyzed using DWBA calculations with microscopic form factors to obtain Jπ and to locate multiparticle-multihole strength in 16N: see 16.7 (in PDF or PS). Measurements at Eα = 34.9 MeV are summarized in 16.5 (in PDF or PS) of (1986AJ04). See also (1988MIZY, 1988BRZY).
For reaction (a) see (1971AJ02). Resonances observed in reactions (b, c, d) are displayed in 16.5 (in PDF or PS) of (1982AJ01). Total cross sections for reaction (b) have been measured for 0.2 ≤ Ec.m. ≤ 2.1 MeV (1992BR05).
At Eα = 46 MeV the angular distributions of the groups to 16N*(0.30, 3.96, 5.73, 7.60) have been determined: the most strongly populated state is the (5+) state 16N*(5.73). See (1971AJ02).
The thermal cross section is 24 ± 8 μb: see (1981MUZQ).
The scattering amplitude (bound) a = 6.44 ± 0.03 fm, σfree = 4.59 ± 0.05 b, σspininc (bound nucleus) < 1 mb (1979KO26). The total cross section has been measured for En = 0.4 to 32 MeV: see (1977AJ02, 1981MUZQ). Observed resonances are displayed in 16.10 (in PDF or PS). See also (1986AJ04, 1988MCZT, 1989FU1J).
The activation cross section was measured for neutron energies between 14.6 and 15.0 MeV (1986RO1C).
This reaction was studied with 200 MeV protons for Ex ≤ 30 MeV (1987AZZZ). A strong transition to a state with Jπ = 5+ was observed at Ex = 5.7 MeV. Strong states were also observed at Ex = 14.2 and 16.1 MeV with cross sections falling sharply with angle.
Levels derived from observed proton groups and γ-rays are shown in 16.11 (in PDF or PS). Gamma transitions are shown in the inset of Fig. 2. The very strong evidence for Jπ = 2-, 0-, 3- and 1-, respectively for 16N*(0, 0.12, 0.30, 0.40) is reviewed in (1971AJ02). These states provide a probe of the residual interaction relating the 1p and 2s 1d shells. See (1984BI03) for a comparison of experiment and theory for M1 observables. See also (1986AJ04, 1986ME1A, 1988VI1A).
Partial μ--capture rates have been observed to 16N*(0.12, 0.40) [Jπ = 0-, 1-] (1979GU06). The rate for capture by the Jπ = 0- state ["best" value: λμ = 1560 ± 94 sec-1 (1985HE08)] and the "reverse" reaction 16N*(0-) β/→ (β over a rightarrow) 16O(0+) [see reaction 1] were the first reactions which verify the prediction (1978GU05, 1978GU07, 1978KU1A) of a large meson-exchange contribution to the weak, rank-zero axial charge. See reaction 1 and (1981TO16, 1986NO04, 1990HA35, 1992WA1L). See also the measurement reported in (1990BL1H) and the calculation of (1990CH13).
Pion spectra have been obtained with the virtual photons in the energy range Eγ = 200 - 350 MeV (1987JE02). Cross sections corresponding to the population of the four lowest states of 16N (unresolved) were measured. Angular distributions were measured (1987YA02, 1987YA1D) at a photon energy of 320 MeV and the results compared to DWIA calculations. Measurements at Ee = 200 MeV and Eπ+ = 30 MeV are cited in (1986AJ04).
At En = 59.6 MeV differential cross sections for the protons to the first four states of 16N (unresolved) and to 16N*(6.2, 7.8) have been analyzed by DWBA. Comparisons are made with results from the 16O(γ, n) and 15N(p, γ0) reactions in the GDR region of 16O (1982NE04, 1984BR03). See also (1983SCZR, 1988NO1B, 1989BOYV). Other (n, p)-like charge exchange reactions are reviewed in (1989GA26), and data in (16O, 16N) is presented in (1988HE1I).
Measurements at E(7Li) = 50 MeV to 16N*(0, 0.12, 0.30, 0.40, 3.35, 3.52, 3.96, 5.52, 5.73, 6.17) are reviewed in (1986AJ04). A microscopic DWBA Coupled-Channels analysis of data at E(7Li) = 50 MeV is reported in (1986CL03). See also the review of charge-exchange reactions with 7Li ions in (1989GA26).
Bremsstrahlung-weighted integrated cross sections have been measured (1989OR07). About 90% of the photoproton emission populates the ground state (2-) and the 0.298 MeV (3-) levels. The 0.120 MeV (0-) and 0.397 MeV (1-) levels are also populated. See also (1986OR1A). Measurements with quasimonoenergetic photons at Eγ = 13.50 - 43.15 MeV were carried out by (1992ZU01) to study the GDR in 17O.
Coincidence measurements for Eπ = 116 MeV, θp1 = 50°, θp2 variable have been reported by (1986SC28, 1986SCZX). Transitions to the unresolved cluster of 4 states below 0.4 MeV excitation were observed to account for 6.1 ± 0.6% of the estimated two-nucleon absorption cross section below 20 MeV excitation. The results were compared with a model of pion absorption on quasi-deuteron pairs.
At Ep = 43 MeV, the angular distribution of the 3He nuclei corresponding to a state at Ex = 9.9 MeV fixes L = 0 and therefore Jπ = 0+ for 16N*(9.9): it is presumably the T = 2 analog of the ground state of 16C. See (1982AJ01, 1986AJ04). See also (1985BLZY).
Alpha particle groups observed in this reaction are displayed in 16.11 (in PDF or PS). For polarization studies see (1982AJ01) and 20F in (1983AJ01, 1987AJ02). τm for 16N*(0.40) = 6.5 ± 0.5 psec and |g| = 1.83 ± 0.13: see (1982AJ01).