(See Energy Level Diagrams for 15O)
Model calculations: (1960TA1E, 1960TA1C, 1963CO12, 1963KU1B, 1964AL1L, 1964AM1D, 1964BR1H, 1964RI1A, 1965CO25, 1965GI1B, 1965GR1H, 1965GU1A, 1965HU1D, 1966BO1R, 1966EL08, 1966RI1F, 1966SO05, 1967BO1T, 1967EL03, 1968DE13, 1968EL1A, 1968HO1H, 1968MA2B, 1968SH08, 1968WO1C, 1968ZH1B, 1968ZU02, 1969DE16, 1969EL1B, 1969GU1M, 1969SA1J).
Reported half-lives are listed in Table 15.19 (in PDF or PS) (1954KL36, 1955BA83, 1957KI22, 1957PE12, 1959KI99, 1960JA12): the weighted mean is 122.24 ± 0.16 sec. See also (1963CS02, 1963VA31). Using this value for τ1/2 and Qm, log ft = 3.643. See also (1968BA42) and (1965GA1D, 1966MI1F, 1967AM1H, 1968SH08, 1969LE1D, 1969SU15; theor.).
Excitation functions for these reactions have been measured over a wide range of energies: see Table 15.20 (in PDF or PS). Observed resonances are displayed in Table 15.21 (in PDF or PS). For discussions of angular distribution measurements which have been measured at many energies over the range displayed in Table 15.20 (in PDF or PS), see the writeups of 8Be in (1966LA04), 11C and 12C in (1968AJ02), and 13N, 14N, and 14O. See also (1964DE1E).
Consideration of the relative yields at E(3He) = 1.21 and 2.15 MeV lead to the tentative Jπ assignments given in Table 15.21 (in PDF or PS) for 15O*(13.00, 13.79) (1957BR18). The assignments for 15O*(14.03, 14.27, 14.46) are derived from analyses of the 3He elastic scattering, particle and γ6.44 angular distributions, and the total cross sections of the n0 and p1 groups (1964KU05). Above E(3He) ≈ 5 MeV, the excitation functions show broad maxima (see Table 15.21 (in PDF or PS)) but it is not clear that they correspond to excited states in 15O: for instance the maxima in the yields of n0 (1964DE1C), p6, d0, α0 and α1 (1960HI07) are not correlated. See, however, (1969WE08). The structures observed in the excitation functions for p0 → p9 at E(3He) = 4.6 to 11 MeV are attributed to quasi-giant resonances involving single proton orbitals coupled to excited 14N core configurations (1969HA49). Above E(3He) ≈ 12 MeV, the excitation functions do not show clear resonant behavior: see, e.g. (1967GR1L, 1968FO06, 1969FO02).
Broad resonance-like structures in the yield of protons are reported at E(3He) = 7.0, 7.8, 9.6, 10.6, 13.4 and 14.6 MeV [Γ ≈ 1 MeV] (1970SP1E).
Over the range E(3He) = 6.5 → 11 MeV, the ratio dσn/dσp1 [to 14Og.s. and the first T = 1 state of 14N), determined at 10°, is approximately constant and ≈ 2, as would be expected if isospin were conserved and if Coulomb scattering and Q-value differences can be neglected (1965FU16). (1968LA19) find that the compound nucleus level overlap parameter Γ/D0 and the spin cut-off parameter σ as obtained from elastic scattering and from the statistical model analysis of three proton groups [E(3He) = 5.29 - 5.50 MeV] are constant. See also (1970CA1G).
For a survey of the energies at which polarization measurements have been made, see Table 15.20 (in PDF or PS). (1968HU1A) find that at E(3He) = 36 and 42 MeV, the 3He polarization results are such that optical model calculations require an optical spin-orbit potential depth ≤ 3.5 MeV. See also (1959AJ76).
Angular distributions of neutrons corresponding to the ground state of 15O have been measured at E(3He) = 1.70 to 5.35 MeV (1965DI07), 2.6, 2.8 and 3.1 MeV (1961JO07, 1961JO24), 2.66 MeV (1961DU1B, 1963DU12: also n3), 5.0 and 6.2 MeV (1969HO1F: also to 15O*(6.18, 6.86, 8.92, 8.98, 9.50, 9.60, 9.66) and 7.8, 8.6 amd 10.1 MeV (1964DE1C). DWBA analyses have been made: (1969HO1F) find L = 0 for 15O*(0, 8.92, 8.98, 9.66) and L = 2 for 15O*(6.18, 9.49, 9.60). At E(3He) = 11.6 MeV, a neutron group assigned to a T = 3/2 state at 11.5 ± 0.10 is reported by (1969BR30).
Observed resonances are listed in Table 15.23 (in PDF or PS) (1951DU08, 1955BA83, 1957PIZZ, 1959GA05, 1959HE47, 1959PO79, 1959VA04, 1959VA08, 1960TA17, 1963HE11, 1966EV01, 1967EV02, 1969OC1B). Branching ratios are displayed in Table 15.22 (in PDF or PS) (1960TA17, 1963HE11, 1966EV01).
The cross section increases from (8.5 ± 3.7) × 10-12 b at 100 keV to (140 ± 30) × 10-12 b at 135 keV (1957LA13). Extrapolation from the Ep = 0.28 MeV resonance gives S(0) = 2.75 ± 0.50 keV · b, with zero slope to Ep = 0.05 MeV (1963HE11). For astrophysical implications, see (1964FO1A, CA65, 1968DU1F). The Jπ assignments shown in Table 15.23 (in PDF or PS) arise from considerations of branching ratios, measurements of angular distributions of γ-rays and the studies discussed in reaction 10. Angular correlation measurements also lead to Jπ = 3/2+ and 3/2- for 15O*(6.79, 6.18). The results are also consistent with J = 1/2 for 15O*(5.18) (1959PO79). Energies for states involved in the cascade decays are Ex = 5.19 ± 0.01, 6.15 ± 0.03 and 6.79 ± 0.01 MeV (1959PO79), 5.168 ± 0.015, 6.154 ± 0.010, 6.788 ± 0.008 MeV (1960TA17). At Ep = 0.8 MeV, the non-resonant radiation goes primarily [(81 ± 3%)] via cascades through 15O*(5.2, 6.18, 6.79) (1963BA1P). See also (1959HE47).
The excitation function for γ0 for Ep = 6.4 to 19 MeV is characterized by four very pronounced peaks, ≈ 1 MeV, wide, below Ex = 19 MeV. The 90° excitation function then shows a giant resonance peak centered at Ex ≈ 21 MeV (1968KU1F): see, however, (1959CO1C, 1961CO02). See also (1964TA05).
The yields of elastic and inelastic protons, and of γ-rays have been studied at many energies: see (1959AJ76) and Table 15.24 (in PDF or PS). The scattering anomalies are superposed on a background which decreases less rapidly than the Rutherford cross section; for Ep < 2.3 MeV, the background is largely s-wave with some p-wave contribution above Ep = 1.5 MeV.
Observed resonances are displayed in Table 15.23 (in PDF or PS): see (1959AJ76) and (1959BA16, 1959VA08, 1963CO13, 1967KU1M, 1967LA05, 1967LA10, 1968SH11, 1969WE02). At Ep = 9, 10 and 10.7 MeV, broad structures, possibly intermediate-state resonances, are reported by (1968BO36). See also (1961TA06, 1964DO03, 1966MA02) and (1969AL1H; theor.).
Polarization studies have been made at many energies: see Table 15.24 (in PDF or PS) (1961RO05, 1961RO13, 1965RO22, 1966BE1M, 1966BR09, 1966DR02, 1966ST05, 1968GE04). See also the reviews in (1966RO1R, 1966RO1B, 1969WA11) and (1965TA07; theor.).
For reaction (b), see (1966MA02).
The excitation function has been measured for Ep = 6.3 to 12 MeV. Broad resonances are observed for Ep = 7.5 to 9.85 MeV: see Table 15.23 (in PDF or PS) (1964KU06). Broad resonance structure continues in the region up to Ep ≈ 16.5 MeV (1966KU12). See also (1963VA1C, 1965VA23, 1969VE02), (1969AL1H; theor.) and 14O. See also (1966RE1D, 1969BA1N) for astrophysical considerations.
See 12N in (1968AJ02).
In the range Ep = 6 to 9 MeV, the cross section for ground state α-particles is large and shows many resonances: see Table 15.23 (in PDF or PS) (1968SH11). Integrated cross sections for α0 and α1 are also reported for Ep = 8.2 to 10.5 MeV by (1968SH11). See also (1952BL64, 1963VA1C, 1966MA02, 1969WE02) and see (1966RE1D) for astrophysical implications.
Angular distribution studies have been conducted at many energies: see Table 15.26 (in PDF or PS) (1953EV03, 1960EL04, 1960MO18, 1960RE07, 1962GR18, 1963CH1D, 1963GI16, 1965SI13, 1966LO1N, 1967MU12, 1968RI1T, 1969RI1C). Information derived from DWBA analysis of the angular distributions, and from the very accurate γ-ray measurements of (1965WA16, 1966AL18, 1967CH19) are shown in Table 15.27 (in PDF or PS).
Neutron thresholds have been observed at Ed = 0.143 ± 0.004 and 0.206 ± 0.005 MeV (1963CS02), 1.24 ± 0.02, 1.967 ± 0.004 and 2.044 ± 0.004 (1955MA85), corresponding to 15O*(5.19, 5.25, 6.15, 6.79, 6.86). See also (1965MA1K).
Gamma ray branding ratios are shown in Table 15.22 (in PDF or PS) (1965WA16, 1968GI11). Lifetime measurements are listed in Table 15.25 (in PDF or PS) (1965AL19, 1965WA03, 1966AL18, 1967BI11, 1968GI11). See also (1959MO10, 1966AV1A).
Angular distributions obtained at E(3He) = 11 MeV (1968BO14) and 14 MeV (1969AL04) have been analyzed by DWBA: see Table 15.27 (in PDF or PS). The angular distribution of deuterons has also been measured at E(3He) = 5.1 MeV (1960FO01). For reaction (b) see (1967AD1F) and 16F in (1971AJ02).
Angular distributions of tritons corresponding to the ground state of 15O have been determined at Eα = 43 MeV (1967DE1K) and at 56 MeV (1968GA1C, 1969GA11). At the higher energy, a detailed comparison is made with the results from the mirror reaction 14N(α, 3He)15N (1969GA11).
Angular distributions of ground state neutrons have been measured at Ep = 3.95 to 5.99 MeV (1958JO28), 3.95 to 8.99 MeV, 11.4 and 13.6 MeV (1963HA46; also n2 at Ep = 5.5 MeV), 5.5 to 13.6 MeV (1961WO03) and 18.5 MeV (1964AN1B). See also (1961SA01), (1968WO1D), (1964SA1D, 1968HA15; theor.), and 16O in (1971AJ02).
A number of triton groups have been seen in this reaction. Angular distributions of these at E(3He) = 39.8 and 44.6 MeV, analyzed using a local two-body interaction with an arbitrary spin-isospin exchange mixture, lead to the L-values shown in Table 15.28 (in PDF or PS) (1967BA13, 1968BA1E, 1969BA06). See also (1966EC1B, 1969BO13).
The spectrum of photoneutrons has been investigated at many energies. Measurements over the giant dipole resonance region show the predominant strength is to the Jπ = 1/2- and 3/2- states at Ex = 0 and 6.18 MeV, consistent with the basic validity of the single-particle, single-hole theory of photoexcitation in 16O. However, the two positive parity states at Ex = 5.18 and 5.24 MeV MeV are also strongly populated, auggesting some non-single-particle excitation in that region in 16O (1965CA14, 1965MA45, 1966OW01, 1967CA1C, 1967CA1P, 1968BA2L, 1969UL01). See also (1963FU05, 1964TA1C, 1965WI03, 1967FI1E, 1968JO1H, 1969CO15, 1969HO1T, 1969JO1N, 1969MU07). See also (1968ZH1B; theor.). For lifetime measurements of 15O*, see Table 15.25 (in PDF or PS) (1969MU07). See also 16O in (1971AJ02).
Reaction (a) goes primarily to the ground state and 6.18 MeV state (Jπ = 1/2- and 3/2-, respectively). Angular distributions have been reported at many energies: see Table 15.29 (in PDF or PS) (1961LE1A, 1963KA26, 1963LE03, 1966GR1A, 1967CH15, 1968LE01, 1969BA05, 1969SN03). See also (1968SH08; theor.). The energy of 15O*(7.28) is 7.285 ± 0.010 MeV (1966MA1A). See also (1964BA04, 1966SH1A).
Angular distributions have been measured at Ed = 15 MeV (1961KE01; t0), 20 MeV (1961VL02; t0), 20 MeV (1969PU04; t0, t1, t2, t3; In = 1, 0, 2, 1) and 28 MeV (1968GA13; t0). At Ed = 28 MeV, detailed comparison is made with the results from the mirror reaction 16O(d, 3He)15N (1968GA13).
The p1/2 and p3/2 hole states at Ex = 0 and 6.18 MeV are strongly populated in this reaction, see e.g. (1965WA17). Information on these and other states of 15O observed in this reaction is shown in Table 15.30 (in PDF or PS) (1959HI68, 1959YO25, 1967HE1A, 1968BO14). The J-values are derived from angular correlation measurements (1967HE1A, 1966GA19, 1966GO15, 1967GO07, 1968GI01): see also (1968BO14). Angular distributions have been measured for E(3He) = 5.2 to 36.6 MeV: see Table 15.31 (in PDF or PS) (1959HI73, 1960TA12, 1962SE13, 1965AL05, 1965AR07, 1968BO14, 1969BR07). Branching ratios are displayed in Table 15.22 (in PDF or PS) (1965WA16, 1969KU01). See also (1965WA03). The lifetimes of 15O*(5.18, 5.24) are < 0.3 and > 1 psec, respectively (1965AL19): see also Table 15.25 (in PDF or PS). A comparison of the 5 MeV transitions E3/M2 mixing ratios in 15O and 15N strongly suggest a collective character for the E3 component of these transitions (1968GI01).
The ratio of mixing ratios of the mirror decays 15O*(6.18 → 0) and 15N*(6.32 → 0) are in disagreement with the IPM suggesting a collective contribution to the mirror 3/2- levels (1966RO1U).
The M2/E1 mixing ratio for the 15O*(6.79) transition indicates an exceptionally high retardation of an E1 transition in a non-self-conjugate nucleus, as is also true of the analog transition in 15N (1968GI01).
The Ex = 7.28 MeV state, J = 7/2, has a negligable effect on the (astrophysical) CNO cycle (1967HE1A).