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14O (1976AJ04)(See Energy Level Diagrams for 14O) GENERAL: See also (1970AJ04) and Table 14.29 [Table of Energy Levels] (in PDF or PS). Nuclear models: (1973SA30, 1974KU1F). Special reactions involving 14O: (1971AR02, 1973BA81, 1974BA89, 1975HU14). Reactions involving pions: (1973CH20, 1973DA37, 1975HU1D, 1975RE01). Other topics: (1970FO1B, 1972AN05, 1972CA37, 1972KU1C, 1973GO1H, 1973KA1H, 1973PA1F, 1973RO1R, 1973SP1A, 1974BO22, 1974KU1F, 1974SE1B, 1974VA24, 1975BU1M). Ground state: (1975BE31).
The adopted half-life of 14O is 70.599 ± 0.022 sec (1975HA45). Recent measured values are τ1/2 = 70.588 ± 0.028 sec (1971CL07, 1973CL12), 70.48 ± 0.15 sec (1972AL01), 70.32 ± 0.12 sec (1972SI50), 70.43 ± 0.18 sec (1974AZ01). 14O [Jπ = 0+; T = 1] decays predominantly to the analog state 14N*(2.31): the branching ratio to that state is 99.328 ± 0.012%. This value is obtained by adopting 0.61 ± 0.01% (1966SI05) and 0.062 ± 0.007% (1969KA1B) for the branching ratios to 14N*(0, 3.95) [both 1+; 0 states]. The ft value for the 0+ → 0+ transition (to 14N*(2.31)), based on the 99.328% branching ratio, the adopted τ1/2, a Q for the transition of 2831.83 ± 0.36 keV, is 3084.3 ± 3.6 sec (1975HA45). See also (1973CL12, 1973HA2E). The question of how ft values for 0+ → 0+ transitions should be calculated has been studied by many other groups: see, e.g., (1972JA19, 1972WI05, 1973TO04, 1974RO21, 1974WI02; theor.). The importance of the question relates to the determination of the fundamental coupling constant Gv; see the discussion in (1975HA45). See also (1970AJ04). The ft values for the transitions to 14N*(0, 3.95) are, respectively, (1.9 ± 0.2) × 107 (1969KA1B) and 1200 ± 150 (1969KA1B). For a summary of earlier values see Table 14.27 (in PDF or PS) in (1970AJ04). See also (1975RA37), (1969BL1D, 1969LY1A, 1970HU08, 1970JA02, 1970LA1L, 1970PA23, 1971FA17, 1971HU10, 1971JA20, 1972AR20, 1972BE04, 1972WI28, 1972WI1C, 1973HA49, 1973WI1J, 1974AS07, 1974BO18, 1974KR09, 1975WI1K, 1975WI1E, 1976LO01; theor.).
[See also Table 14.28 (in PDF or PS) in (1970AJ04).] Observed neutron groups are displayed in Table 14.30 (in PDF or PS). Angular distributions have been studied at many energies: among the recent measurements are those by (1970AD01, 1970AD02: E(3He) = 10 to 15 MeV), (1972BR60: 13.3 and 18.2 MeV) and (1971GRYL, 1972GR39: 25.4 MeV). For earlier measurements see (1970AJ04). A study of n - p coincidences (14O* → 13N + p leads to J and Γ assignments for 14O*(5.92, 6.27, 6.59, 7.77) (1973PR08): see Table 14.30 (in PDF or PS). See also (1971KL1C, 1973JU1B, 1973RH1A, 1974AD11, 1974GO23), (1974GR39; theor.) and 15O.
At E(11B) = 114 MeV, 14O*(6.27, 9.9) [Jπ = 3- and 4+, respectively] are populated: see (1973SC1J, 1974AN36).
At E(12C) = 114 MeV, the population of 14O*(0, 6.27, 9.9) is reported: it is suggested that 14O*(9.9) has a (d5/2)24+; 1 configuration (1971SC1F, 1972SC21, 1974AN36). 14Og.s. is weakly populated (1974AN36).
At E(14N) = 118 MeV, the population of 14O*(6.27, 9.9) is reported (1974AN36). At E(14N) = 155 MeV there is some evidence for the excitation of 14O*(5.17, 5.92, 6.27, 8.74, 9.72) (1975NA11).
At Ep = 185 MeV, an angular distribution has been obtained for the transition to 14Og.s.: in the range 35° - 130° it shows no peaking (1973DA37).
See (1970AJ04) for the earlier work. See also (1970WI1B, 1971BE46, 1971TH1D) and (1970LO1B; theor.). [The earlier reported angular distributions have not been published.]
Triton groups have been observed at E(3He) = 44.6 MeV to the first six states shown in Table 14.29 (in PDF or PS) and to levels with Ex = 6.79 ± 0.03, 8.74 ± 0.06, 9.74 ± 0.03, 10.89 ± 0.05, 11.24 ± 0.05, 11.97 (unresolved), 12.84 ± 0.05, 13.01 ± 0.05, 14.15 ± 0.04, 14.64 ± 0.06 and 17.40 ± 0.06 MeV (1967BA13, 1969BA06). See also (1968BA1E) and reaction 47 in 14N. [The states at 6.79 and 8.74 MeV reported in this reaction are relatively weakly excited and are not observed in reaction 2.]
See (1970AJ04).
Angular distributions of ground state tritons have been studied at Ep = 27 MeV (1973IN05), 32.2, 36.6 and 43.5 MeV (1975MI01), 43.7 and 54.1 MeV (1964CE02, 1971FL04), 43.8 MeV (1970HA23: pol. p) and 49.5 MeV (1970NE17, 1970NE1B: pol. p). Angular distributions have also been studied with polarized protons at Ep = 43.8 MeV to 14O*(0, 5.17, 6.27, 6.59, 7.77, 9.72) (1974MA12). The ratio of (p, 3He) [to the analog state in 14N at 2.31 MeV] to (p, t) [to 14Og.s.] is correctly predicted by DWBA calculations: see, e.g., (1974CR01). Triton groups have also been observed to states with Ex = 5.21 ± 0.04, 5.92 ± 0.06, 6.28 ± 0.05, 6.59, 7.78, 8.69 ± 0.06 [weak, not observed in reaction 2], and 9.65 ± 0.06 MeV (1971FL04) and to 14O*(6.59, 7.77, 9.71) (1970HA23). The Jπ assignments derived from these two papers and from (1974MA12, 1975KU22) are in agreement with the values shown in Table 14.29 (in PDF or PS). See also (1969SC1F, 1972HA1X, 1974AD1B), (1971KA04, 1974ST16; theor.) and 17F in (1977AJ02).
At Eα = 58 MeV the differential cross section for populating 14Og.s. ≲ 0.4 μb at θlab = 21° (1975VA01).
At Eα = 58 MeV the differential cross section is 40 ± 15 nb/sr at θlab = 8° (1975JA10).
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