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14O (1970AJ04)

(See Energy Level Diagrams for 14O)

GENERAL: See Table 14.26 [Table of Energy Levels] (in PDF or PS).

See (1959OT1A, 1960PI1C, 1960TA1C, 1961FR1C, 1963BL1B, 1964LO1B, 1965KO1D, 1966BO1R, 1966KE16, 1966MI1G, 1967AU1B, 1968EI1C, 1968FA1B, 1968NE1C, 1969GA1G, 1969SO08).

1. 14O(β+)14N Qm = 5.144

The decay proceeds primarily to the Jπ = 0+; T = 1 first excited state of 14N: see Table 14.27 (in PDF or PS). Weak branches are also observed to the ground state of 14N and to the 3.95 MeV state.

The ground-state decay is considerably faster than the mirror transition 14C → 14N supporting the hypothesis that both decays are inhibited by accidental cancellation of matrix elements: see 14C and (1968RO1C).

The decay of 14N*(2.31) is an example of pure Fermi 0 → 0 transition and provides a precise determination of the fundamental coupling constant GV (see surveys by (1964WU01, 1966FR15, 1968MO1F)). GV = 1.4025 × 10-49 erg · cm3 (1962BA26), 1.409 × 10-49 erg · cm3 (1968BR1L: see (1969DA06)), 1.407 × 10-49 erg · cm3 (1969DA06). See also (1959KI1C, 1960BA36, 1967BL24, 1968BE03). According to the hypothesis of a universal weak interaction, with conserved vector current, GV = Gμ, the coupling constant for muon decay. The mean for seven cases cited by (1966FR15) is (Gμ - GV/Gμ = (2.2 ± 0.1 ± 0.5)%, where the second error reflects the uncertainty of radiative corrections. See also (1962BA26, 1968BR1L, 1969BL1E, 1969DA06).

The transition to 14N*(3.95) appears to be super allowed. See also (1962BR16, 1964GA1B, 1966FR15, 1966CH1J, 1966MAZY, 1969LO1F).

The polarization of the positrons has been studied by (1959GE36, 1961HO04). See also (1959AJ76) and (1958AL1E, 1959JA1B, 1960DU1B, 1961BL1A, 1962AL1F, 1962WE09, 1962WE1H, 1962BL1D, 1963LO04, 1964BA1T, 1965BL1E, 1964NA1C, 1965MI1B, 1966BA1A, 1966MA57, 1967CH24, 1967SA1H, 1968BH1C, 1968DA1J, 1968HA38, 1968LA1J, 1968YA1F).

2. 10B(6Li, 2n)14O Qm = 1.990

See (1957NO17).

3. 12C(3He, n)14O Qm = -1.148

Reported values of the threshold energy are displayed in Table 14.28 (in PDF or PS). Neutron groups have been observed corresponding to 14O states at 5.17 (1967AD1D, 1968TO09), 5.905 ± 0.012, 6.30 ± 0.03 and 6.586 ± 0.012 MeV, with widths ≤ 60, 120 and ≤ 60 keV, respectively (1961TO03). Higher excited states at 7.78 (1967AD1D), 8.0 ± 0.4, 10.1 ± 0.4 and 13.3 ± 0.4 MeV are reported by (1964BR13). Angular distributions are reported at many energies from 1.9 to 25 MeV: see (1957BR18, 1960AJ03, 1960GA13, 1963MA22, 1964DE1C, 1964DI02, 1964KU05, 1967AD1D, 1967MC03, 1967SC27, 1968TO09).

The angular distributions for n0 and for p1, to 14N*(2.3), show strng forward peaking in the range E(3He) = 6.5 to 11 MeV. The distributions are similar in detail, and well fitted by plane wave direct interaction theory with L = 0. Excitation functions at θ = 10° show marked energy dependence, but (dσn/dσp) is nearly constant at the expected value of 2.0 (1965FU16). Angular distributions (at E(3He) = 9.2 and 10.2 MeV) of the 3He groups to 14O*(0, 5.17, 5.91, 6.29), analyzed by DWBA double stripping theory, give L = 0; L = 1 or (0); L = 0 or (1); L = 3 or 4, respectively. These fits, taken together with the relatively sharp widths of the three excited states (see Table 14.25 (in PDF or PS)), lead to probable Jπ for 14O*(5.17, 5.91, 6.29) of 1-, 0+, 3-, respectively (1968TO09). See also (1960NE1A, 1961GI1B, 1963GL1C, 1964HE06, 1965BR1H, 1966HA1Q, 1966SH1F, 1967CH19) and 15O.

4. 14N(p, n)14O Qm = -5.927
Ethresh. = 6.3544 ± 0.0016 (1968FR08);
Ethresh. = 6.3588 ± 0.0030 (1956KU1A; see also (1964KU06)).

The angular distribution of ground state neutrons has been determined at Ep = 14.8 and 31.5 MeV (1960DA06, 1961AD02). Neutron groups are reported corresponding to broad or unresolved states at Ex ≈ 6.2, 7.5 and 9.3 MeV (1954AJ11). See also (1966SI05, 1968RI1Q, 1969MA1G, 1969PA1J, 1969VE02).

5. 14N(3He, t)14O Qm = -5.163

Triton groups observed at E(3He) = 44.6 MeV are displayed in Table 14.29 (in PDF or PS). Comparisons of angular distributions of the tritons to the first eight states of 14O with those of triton groups in other reactions involving known l-transfers lead to the Jπ assignements quoted in the table (1967BA13, 1969BA06). See also (1968BA1E) and reaction 45 in 14N.

6. 16O(γ, 2n)14O Qm = -28.887

See (1959OC07, 1962BR16, 1964MO26).

7. 16O(p, t)14O Qm = -20.406

The angular distribution of ground state protons has been determined at Ep = 43.7 (1964CE02). See also (1966CE05, 1969SO08).