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USNDP

18F (1972AJ02)


(See Energy Level Diagrams for 18F)

GENERAL: See also (1959AJ76) and Table 18.10 [Table of Energy Levels] (in PDF or PS).

Shell model: (1957WI1E, 1959BR1E, 1960TA1C, 1961TR1B, 1962TA1D, 1964FE02, 1964IN03, 1964PA1D, 1964YO1B, 1965BA1J, 1965DE1H, 1965GI1B, 1966BA2E, 1966BA2C, 1966HU09, 1966IN01, 1966KU05, 1966RI1F, 1967EN01, 1967EV1C, 1967FE01, 1967FL01, 1967HO11, 1967IN03, 1967KU09, 1967KU13, 1967LY02, 1967MO1J, 1967PA1K, 1967PI1B, 1967VI1B, 1967WO1C, 1968AR02, 1968BE1T, 1968BH1B, 1968CL03, 1968CO11, 1968DE1M, 1968DE13, 1968EL1C, 1968FR03, 1968GA16, 1968GU1E, 1968HA17, 1968HA1P, 1968HE1H, 1968KA1C, 1968KU1E, 1968NA09, 1968ZU02, 1969BA2F, 1969BE1T, 1969BU15, 1969KA09, 1969KU1G, 1969MA1T, 1969ME06, 1969ST1G, 1969ZU1B, 1969ZU03, 1970BA2E, 1970EL1G, 1970EL08, 1970HA49, 1970KA32, 1970TR08, 1970WA1T, 1971AR1R, 1971EL07, 1971GU21, 1971HO12, 1971JA06, 1971LO23, 1971PE1A, 1971PR16, 1971QU01, 1971WI01, 1972KA01, 1972LE1L).

Cluster, collective and deformed models: (1964KE1A, 1964MA1G, 1966PI1B, 1966RI1F, 1967FE01, 1967PA1K, 1968EL1C, 1969BA2E, 1969ZA1D, 1970BA2B, 1970WA1T, 1971AR1R, 1972LE1L).

Astrophysical questions: (1970BA1M).

Electromagnetic transitions: (1962MO1A, 1963BU11, 1966HA31, 1967IN03, 1968EL1C, 1968HA17, 1968HE1G, 1968LE02, 1969BE1T, 1969HA1F, 1969WA1C, 1970EL08, 1970HA49, 1970WA31, 1970WA1T).

Special levels: (1964KE1A, 1965GI1B, 1966HU09, 1966MI1G, 1966NA1B, 1967EN01, 1967EV1C, 1967FL01, 1967PA1K, 1967VI1B, 1968AR02, 1968BH1B, 1968CO11, 1968FR03, 1968GA16, 1968HA1P, 1968HE1G, 1968KA1C, 1968LE02, 1968NA09, 1968NO1C, 1969BA1Z, 1969BE1T, 1969CH1K, 1969EL1A, 1969FE1A, 1969HA1F, 1969KA09, 1969KA29, 1969MA1T, 1969ME06, 1969OS01, 1970EL1G, 1970EL08, 1971AR1R, 1971EL07, 1971GU21, 1971JA06, 1971PE1A, 1971PR16, 1971QU01, 1972KA01).

Other theoretical topics: (1961MA1B, 1962IN1A, 1963BU11, 1963VL1A, 1964IN03, 1964ST1B, 1965DE1H, 1965FO1E, 1965KA1B, 1966GI1A, 1966HE1E, 1966KU05, 1967FE01, 1967FL01, 1967KU13, 1967MA1B, 1967MO1J, 1967WO1C, 1968BA2H, 1968BE1T, 1968DE1M, 1968EL1C, 1968GU1E, 1968JO1C, 1968KA1C, 1968KU1E, 1968LE02, 1968MU1B, 1968VA1J, 1968VA24, 1969DE16, 1969GA1Q, 1969KA29, 1969MU09, 1969OS01, 1969PE1D, 1969RA28, 1969WA1F, 1970BA1Z, 1970EL08, 1970PR1D, 1971BA14, 1971BO21, 1971EL07, 1971LO23, 1971PR16, 1972DE05, 1972KA01, 1972LE1L).

Reactions involving pions: (1968BE1F).

Complex reactions involving 18F: (1965LO1D, 1966LA1G, 1967AU1B, 1967WI16, 1967WI20, 1968MO1C, 1968SH1H, 1968ST1L, 1969FE04, 1969KR21, 1970BR13, 1970FA01, 1970FE05, 1970KO1P, 1970KR12, 1970KR1C, 1971AR02, 1971MO1H).

Ground state: (1970WA1T, 1971GU21, 1971WI01, 1972LE1L).

1. 18F(β+)18O Qm = 1.655

The positron decay is entirely to the ground state if 18O [Jπ = 0+; T = 1]: Eβ(max) = 635 ± 2 keV (1964HO28). See also (1959AJ76). The half-life is 109.77 ± 0.05 min: see Table 18.11 (in PDF or PS). log ft = 3.554: see also (1969KA1B). The fact that the β+ transition to 18O(0) is allowed indicates Jπ = 1+ for 18F(0). The ratio εK+ = 0.030 ± 0.002 (1956DR38). See also (1959PE1B, 1966KU1F, 1968DA1J, 1968LE02, 1970MC23, 1971BL12, 1971DE1E, 1971VA1C, 1971WI18; theor.).

2. (a) 12C(6Li, n)17F Qm = 4.064 Eb = 13.215
(b) 12C(6Li, p)17O Qm = 7.606
(c) 12C(6Li, d)16O Qm = 5.688
(d) 12C(6Li, t)15O Qm = -3.723
(e) 12C(6Li, α)14N Qm = 8.799

Cross section measurements have been carried out in the range E(6Li) = 1.9 to 14.0 MeV: see Table 18.12 (in PDF or PS). The cross sections for reactions (b), (c) and (e) rise monotonically and rapidly with energy up to E(6Li) = 4 MeV due to Coulomb barrier effects. At higher energies, Ericson-type fluctuations are observed (1967DZ01, 1970JO09). Neither the direct reaction nor the statistical compound nucleus model alone is adequate to decsribe the data (1970JO09). The cross section for the isospin-forbidden α1 group [to 14N*(2.31), Jπ = 0+; T = 1] shows an energy dependence very unlike those for the α0 and α2 groups, charaterized by a maximum at ≈ 4 MeV, a minimum at ≈ 5 MeV, and a further rise to 6 MeV. Typically the cross section for the α1 group is two orders of magnitude lower than those for the α0 or α2 groups (1965CA06, 1967DZ01). See also (1968NO1C; theor.). For angular distribution studies see 16O and 17O in (1971AJ02) and 14N in (1970AJ04).

3. 12C(7Li, n)18F Qm = 5.964

See (1957NO17, 1961NO05) and 19F.

4. 12C(12C, 6Li)18F Qm = -14.960

See (1962CH01).

5. 14N(α, γ)18F Qm = 4.416

Resonances have been observed at Eα = 0.56, 1.14, 1.40, 1.53, 1.62, 2.35, 2.77 and 2.88 MeV, corresponding to 18F* = 4.85, 5.30, 5.50, 5.61, 5.68, 6.24, 6.57 and 6.65 MeV: see Table 18.13 (in PDF or PS) (1955PR1A, 1958PH37, 1968PA10, 1971CH1F, 1971CO27, 1971RO25). See also (1970AL1F). Capture resonances are not observed corresponding to 18F*(4.66, 4.96), (2J + 1)ΓαΓγ/Γ < 2 × 10-5 and < 0.5 × 10-4 eV, respectively (1971CO27).

The branching ratios for 18F*(5.30, 5.61, 5.68, 6.57) are displayed in Table 18.14 (in PDF or PS).

The sequence of the 18F states with Ex = 1.70 [Jπ = 1+], 2.53 [2+], 3.36 [3+], 5.30 [4+] and 6.57 MeV [5+] as well as the enhanced E2 strengths of the γ-transitions show that these states can be considered to be members of a predominantly 4p-2h Kπ = 1+ rotational band. 18F*(3.36) is found to have J = 3 (1971RO25). The M1 transitions between the Jπ = 1- states at Ex = 5.61 and 5.68 MeV and 18F*(1.08, 3.13) have |M|2 between 0.1 and 1 W.u. implying T = 1 for these resonant states but both also decay by E1 transitions to the T = 1 states at Ex = 1.04 and 3.06 MeV, implying T = 0. This result is in agreement with 18F*(5.61, 5.68) both being 1- members of a T = 0, 1 isospin doublet. The T = 1 strength is split nearly equally between the two levels (1971CH1F). See also (1967CH1J, 1967CH1K).

The non-resonant S factor for this reaction, S ≤ 1.5 × 106 keV · b (1968PA10), ≈ 0.7 MeV · b (1971CO27). See also (1966IB1A, 1971CO1G).

6. 14N(α, n)17F Qm = -4.735 Eb = 4.416

The total cross section ratios of 14N(α, n)17F(0.50)/14N(α, p)17O(0.87) were measured for Eα = 7 to 12 MeV: major maxima are observed at Eα = 8.12, 9.5, 10.07 and 11.52 MeV. Symmetric angular distributions at three of these maxima lead to Jπ = (2-), (2-, 3) and (2-, 3+) at Ex = 10.73, 12.25 and 13.36 MeV. These states are primarily T = 0 (1969SC21): see Table 18.13 (in PDF or PS).

7. 14N(α, p)17O Qm = -1.193 Eb = 4.416

Observed resonances are displayed in Table 18.13 (in PDF or PS) (1953HE1A, 1958HE54, 1958KA32). Excitation functions showing a number of structures have been measured for Eα = 10 to 25 MeV (p0, p1), 13 to 25 MeV (p2) and 15 to 25 MeV (p3) (1970ZE01). See also (1961YA02).

8. (a) 14N(α, α)14N Eb = 4.416
(b) 14N(α, αp)13C Qm = -7.551
(c) 14N(α, d)16O Qm = -3.111

Observed amomalies in the elastic scattering are exhibited in Table 18.13 (in PDF or PS) (1939BR1A, 1939DE1A, 1953HE1A, 1958HE54, 1958HE56, 1958KA32, 1961SI09, 1962JO14, 1970TO03). Resonances in the α1 (isospin "forbidden") and α2 yield are also displayed (1970TO03). See also (1966CH1E). Excitation functions have recently been reported for Eα = 1.0 to 2.4 MeV (1961SI09; α0), 10.2 to 18.3 MeV (1970TO03; α0, α1, α2), 15 to 23 MeV (1962JO14; α0) and 18.2 to 23.5 MeV (1970CH1D; α1). See also (1963NO1B, 1967BO1M, 1969FE10).

In the range Eα = 10.2 to 17.3 MeV compound nucleus formation dominates the α0, α1 and α2 channels. The α1 channel [to the Jπ = 0+; T = 1 state at 2.31 MeV] displays relatively isolated resonances which imply 18F states with large isospin impurities [≈ 10 - 25%]. Comparison of this work with the results from 16O(d, α1) [reaction 16] suggests that the same 18F states are usually involved in both reactions (1970TO03). These data do not support the suggestions by (1968NO1C, 1969NO1B) concerning the importance of direct reactions in isospin violating reactions (1970TO03). See also (1970JO1G).

For reaction (b), see (1967BE30). For spallation cross sections see (1968JA1J, 1968JU1A, 1970BA48, 1970JA1Q, 1970JU1B). For reaction (c), see (1971TH03) and reaction 16. See also (1970VI02) and 14N in (1970AJ04).

9. 14N(6Li, d)18F Qm = 2.943

Angular distributions have been measured for E(6Li) = 5.3 to 6.0 MeV (1968RI13; d0, d1→4).

10. 14N(7Li, t)18F Qm = 1.950

At E(7Li) = 15 MeV, triton groups are observed to the known T = 0 states with Ex < 7.4 MeV: the T = 1 states are not excited although such transitions are not forbidden in principle, suggesting a direct α-transfer mechanism. The transitions to 18F*(1.70, 2.53, 3.36, 4.23, 5.30, 6.57) account for more than one half of the summed cross section at 15°. It is proposed that these states (which are only weakly excited in 16O(3He, p)18F and 17O(3He, d)18F) are predominantly of a 4p-2h nature and are excited by transfer of four nucleons into the (2s, 1d) shell (1968MI09). [See also reaction 5]. See also (1968OG1A).

11. 15N(α, n)18F Qm = -6.418

See (1966AD07).

12. 16O(d, γ)18F Qm = 7.527

The capture cross section rises from 0.1 μb at Ed = 0.4 MeV to 25 μb at 3.5 MeV: Γγ over this range is ≈ 2 eV. The results can be interpreted satisfactorily in terms of compound nucleus formation (1965OW01). See also (1970AL1F) and Table 18.16 (in PDF or PS).

13. (a) 16O(d, n)17F Qm = -1.624 Eb = 7.527
(b) 16O(d, np)16O Qm = -2.225

Excitation functions have been measured for the n0 and n1 groups from threshold to 12 MeV: see Table 18.16 (in PDF or PS) (1961DI06, 1968DI06, 1968MA1C, 1970BA31, 1970DA14, 1970LO01). Some structure is observed: that which is attributed to states in 18F is displayed in Table 18.17 (in PDF or PS) (1955MA85, 1961DI06, 1968MA1C). The coherence energy determined from the yield for Ed = 4.5 to 6.0 MeV is 70 keV for n0 and 67 keV for n1 (1970DA14). See also 17F in (1971AJ02). For polarization measurements see (1971AN1A, 1971TH10) and Table 18.16 (in PDF or PS).

For reaction (b) see (1968CU04).

14. 16O(d, p)17O Qm = 1.918 Eb = 7.527

Excitation functions have been reported recently for several proton groups up to Ed = 13.0 MeV: see Table 18.16 (in PDF or PS) (1959LO59, 1961LO1C, 1962CA20, 1963AM1A, 1963SE12, 1964AM1A, 1964KI1B, 1965LO03, 1968DI06, 1968NG1B, 1969CO12, 1969DU11, 1970DA14). See also (1963DO1B, 1970CA1C).

Some of the maxima in the yield are interpreted in terms of resonances: these are shown in Table 18.17 (in PDF or PS) (1955ST1A, 1956RO1A, 1963AM1A, 1964AM1A, 1968MA53). See also (1959AJ76). The coherence energy determined from the yields is 75 keV for p0, 63 keV for p1 and 62 keV for p3 in the range Ed = 4.0 to 6.0 MeV (1970DA14).

Polarization measurements are reported by (1963AL1D, 1963EV05, 1969CU10, 1970CO1P, 1971BR44, 1971HU1C, 1971KO21): see Table 18.16 (in PDF or PS). Large values of the polarization are observed for Ed = 6.5 to 12.3 MeV: the results are interpreted in terms of a direct interaction mechanism (1963EV05). See also (1967BA1R, 1967MA1F, 1970PE1B; theor.) See also 17O in (1971AJ02).

15. 16O(d, d)16O Eb = 7.527

The yield of elastically scattered deuterons has been measured for Ed ≤ 13.0 MeV: see Table 18.16 (in PDF or PS) (1963AM1A, 1963SE12, 1964AM1A, 1967AL06, 1968DI06, 1968MA53, 1969CO12, 1970DA14). Fluctuations are observed. Some of the maxima are interpreted in terms of 18F states: for these see Table 18.17 (in PDF or PS) (1956BE1B, 1963AM1A, 1964AM1A, 1968MA53). See also (1963DO1B, 1966AL09, 1970VE06, 1971GA1D, 1971SC1Q) and 16O in (1971AJ02). For polarization measurements, see (1969CO12, 1970CO1P, 1971KO21) and Table 18.16 (in PDF or PS).

16. 16O(d, α)14N Qm = 3.110 Eb = 7.527

The yields of various groups of α-particles have been measured for Ed ≤ 20 MeV: see Table 18.16 (in PDF or PS) (1960AM03, 1962CA20, 1963AM1A, 1963SE12, 1963YA1B, 1964AM1A, 1964KI1B, 1965LO03, 1965MA1A, 1965SA18, 1967TH1E, 1968DI06, 1968JO07, 1968TH1J, 1969CO12, 1969JO09, 1969JO1M, 1970AL1F, 1970JO1G, 1970JO1C, 1971JA04, 1971TH03). See also (1963DO1B, 1970CA1C) and (1969NO1C, 1971SC1Q; theor.).

The yield curves have been fitted in terms of a large number of states in 18F: see Table 18.17 (in PDF or PS) (1956BR36, 1957BA14, 1960AM03, 1963AM1A, 1964AM1A, 1965MA1A, 1968JO07, 1969JO09, 1969JO1C, 1970JO1C, 1971JO11). See also (1970JO1F). A detailed study by (1970JO1C) of the isospin-forbidden α1 yield shows that there are no very strong states seen for J > 5, and those seen in J = 7, the highest partial wave needed to fit the yield, are wide, Γ ≈ 300 keV. This contradicts the prediction that isospin violation should be negligable for low spin states while large for those with high J. See also (1971JO11). The average coherence width is ≈ 150 keV for 12 < Ex < 15.5 MeV (1968JO07).

For the isospin-forbidden α1 yield, virtually all the observed levels overlap several others of the same spin and parity in the tail of the resonance. The α1 yield has a smaller cross section than the yield of 14N(α, α1)14N at the same Ex in 18F [see (1970TO03)]. This is most pronounced at high excitation energy and is thought to be related to the very small binding energy of the deuteron. Thus reaction 8 appears to be a better tool to study 18F at high Ex (1970JO1C).

For polarization studies, see (1970PR1C, 1971KE1E). See also 14N in (1970AJ04). Very accurate cross section measurements of the 16O(d, α)14N reaction and of its inverse, 14N(α, d)16O, are consistent with the principle of detailed balance. The lowest uncertainty was ± 0.5%. An upper limit of 0.2% is assigned to the time-reversal non-invariant part of the reaction amplitudes (1971TH03).

17. 16O(t, n)18F Qm = 1.269

Measurements of the strengths and of lifetimes of the radiative decays are displayed in Tables 18.14 (in PDF or PS) and 18.15 (in PDF or PS) (1963LI07, 1966AL04). (1966AL04) report that ΔEx (1.13 → 0.94) = 194 ± 1 keV: Ex of 18F*(1.13) is then 1131.0 ± 1 keV [based on Ex = 937.0 ± 0.2 keV]. See also (1967WA1C) and (1959AJ76).

18. 16O(3He, p)18F Qm = 2.033

Excitation energies derived from measurements of proton spectra (1959HI67, 1959YO25, 1967MA1G, 1968GR1G, 1968GR1H, 1968MA33) and of γ-rays (1960RA18, 1961DU02, 1965CH10, 1967WA06) are displayed in Table 18.18 (in PDF or PS).

Angular distributions of proton groups have been obtained at E(3He) = 4.00 MeV (1964MA50), 5.9 and 9.2 MeV (1959HI74), 15 MeV (1968PO1B, 1969PO11), 18 MeV (1967PU03, 1971BE19) and 19.8 MeV (1967MA1G, 1968MA33). Distorted wave analyses lead to the l-assignments shown in Table 18.18 (in PDF or PS). (1960JA11) have compared the angular distribution they obtained for the 16O(t, p)18O reaction to 18O(0) with the angular distributions obtained by (1959HI74) for 18F*(1.04, 1.08) in this reaction. It is clearly 18F*(1.04) which is the analog to the ground state of 18O: Jπ is then 0+ and T = 1.

The magnetic moment of 18F*(1.13), μ = +(0.568 ± 0.013)J (1967PO09), +(0.572 ± 0.006)J (1967SC09). If J = 5, and all data are consistent with this assignment, μ = 2.855 ± 0.030 nm. This value is in agreement with shell-model predictions for a 5+ state remaining from 1d25/2 (1967PO09).

The γ-decay of many states has been studied: Table 18.14 (in PDF or PS) displays observed branching ratios and radiative widths. Studies of these parameters, coupled with angular correlation and γ-ray angular distribution studies (1961KU02, 1965PO01, 1966CH06, 1966CH12, 1966OL03, 1967GO07, 1967OL03, 1967PO02, 1967WA06), lifetime measurements [see Table 18.15 (in PDF or PS) (1959AL99, 1963LO03, 1966OL03, 1967BE14, 1967PO09, 1967WA06, 1970BL1F)] and the l-values shown in Table 18.18 (in PDF or PS) lead to the Jπ assignments displayed in Table 18.14 (in PDF or PS). See also (1963HI06).

The linear polarization of the 2.10 MeV γ-ray [2.10 → 0], together with the mixing ratio obtained by (1967GO07), leads to an assignment of negative parity to 18F*(2.10), and also to 18F*(1.08). The latter results from the value of τm for 18F*(2.10) and the observation of a P4(cos θ) term in the 2.10 → 1.08 transition (1967PO02).

See also (1964MA57, 1966AG1B, 1970CA28), (1959FA1A) and (1960NE1A; theor.).

19. 16O(α, d)18F Qm = -16.321

At Eα = 40 to 52 MeV, deuteron spectra are dominated by the groups to 18F*(1.13), Jπ = 5+ [1d25/2 configuration] (1962HA40, 1966RI04, 1967MA1G, 1968MA33). Many other states of 18F have also been observed: see Table 18.19 (in PDF or PS) (1966RI04, 1967MA1G, 1968MA33). For configuration assignments, see (1968MA33). See also (1960AG01), (1969BR1D) and (1963GL1C, 1965GR1F, 1967IM1A; theor.).

20. 16O(6Li, α)18F Qm = 6.053

Angular distributions of the α-particles to the ground state of 18F have been measured at E(6Li) = 5.5 to 13.3 MeV (1968GR1H, 1968GR22) and at 26 MeV (1969DA19). The lifetime of 18F*(4.36) is < 0.61 psec (1969TH01): the γ-ray energy for the transition 4.36 → 3.06, Eγ = 1297.4 ± 2.5 keV. Assuming Ex = 3.0598, the energy of 18F*(4.36), Ex = 4.357 ± 0.004 MeV (1969TH01). See also (1967CA1D).

21. 16O(11B, 9Be)18F Qm = -8.290

See (1966PO1E, 1967PO1E).

22. 16O(14N, 12C)18F Qm = -2.746

See (1966GA10, 1969BR1D, 1969RO1G, 1970AN1D).

23. 17O(p, γ)18F Qm = 5.609

The yield of 0.94 MeV γ-rays (γ1) has been measured for Ep = 0.2 to 1.5 MeV. A number of resonances are observed: see Table 18.20 (in PDF or PS) (1969ZA1C, 1971BE1E, 1971SE1H). A strong resonance for 1.04 MeV γ-rays (γ2) is observed, corresponding to 18F*(6.14) (1969ZA1C, 1971SE1H). A study of this resonance shows that 18F*(6.14) has Jπ = 0+. The parity of 18F*(3.72) is found to be even (1970RO1F).

Branching ratios for the decay of 18F* states with 6.09 < Ex < 6.87 MeV are displayed in Table 18.15 (in PDF or PS). DSAM measurements show τm < 15 fsec for these states. From the γ-decay of the resonant states, accurate excitation energies have been determined for a number of low-lying states: Ex = 0.9369 ± 0.2, 1.041 ± 1, 1.121 ± 0.4, 1.700 ± 1, 2.1013 ± 0.5, 2.523 ± 1, 3.136 ± 2, 4.650 ± 1 and 4.965 ± 1 MeV (± keV) (1971SE1H).

24. 17O(p, n)17F Qm = -3.542 Eb = 5.609

The yields of n0, measured for Ep = 7 to 13.5 MeV, and of n1, measured for Ep = 7 to 12.5 MeV, show some gross structures (1969AN06). See also (1965BL07).

25. 17O(p, p)17O Eb = 5.609

The elastic scattering has been studied for Ep = 0.5 to 1.33 MeV (1971SE1J) and for Ep = 11.0 to 13.0 MeV (1967AL06): observed anomalies are displayed in Table 18.20 (in PDF or PS) (1971SE1J).

26. 17O(p, α)14N Qm = 1.193 Eb = 5.609

The yield of ground state α-particles shows a number of resonances for Ep = 0.49 to 3.0 MeV: see Table 18.20 (in PDF or PS) (1957AH20, 1962BR08, 1971SE1J). Astrophysical considerations are discussed by (1962BR08, 1967FO1B).

27. 17O(d, n)18F Qm = 3.384

At Ed = 4.4 MeV angular distributions of the neutrons corresponding to 18F*(0.94, 2.52, 3.06, 3.36, 3.84, 4.96, 5.61, 5.67) have been measured. The cross section for formation of 18F*(5.61) is an order of magnitude greater than for 18F*(5.67), consistent with the interpretation that these (1-) states contain a substantial isospin admixture (1971GA1B, 1971LI1D). See also (1971AR33). For a lifetime measurement, see Table 18.15 (in PDF or PS) (1971LE29). See also 19F.

28. 17O(3He, d)18F Qm = 0.115

At E(3He) = 15 MeV, DWBA analysis of angular distributions of deuteron groups corresponding to the ground state of 18F [l = 2] and to the excited states of 0.94 [l = 0 + 2], 1.04 [2]. 1.12 [2], 2.53 [0 + 2], 3.06 [0 + 2], 3.84 [0 + 2], 4.12 [0 + 2], 4.66 [2] and 4.96 MeV [0 + 2] have been obtained by (1968PO1B, 1969PO11) who also report spectroscopic information. Thus all these states have even parity and 18F*(4.12) may be assigned Jπ = (2+) or 3+. Since l = 2 for 18F*(4.66), Jπ ≤ 5+, with 4+ most likely (1969PO11).

29. 17O(α, t)18F Qm = -14.205

Not reported.

30. 18O(p, n)18F Qm = -2.438

Ethresh. = 2.57372 ± 0.00077 (1964BO13);

Ethresh. = 2.577 ± 0.003 (1967PR04);

Ethresh. = 2.576 ± 0.001, Q0 = -2.439 ± 0.001 (1969BE57). See also (1959AJ76).

Gamma rays are observed with Eγ = 938 ± 6, 1043 ± 8 and 1082 ± 10 keV (1960RA18). See also (1968BE34). The lifetime of 18F*(1.04) is 4+3-2 fsec (1967BL18). Angular distributions have been measured at Ep = 6.9 to 13.5 MeV (n0, n1→4), 6.9 to 9.25 MeV (n5), 7.55 to 9.25 MeV (n6), 7.95 to 9.25 MeV (n7) and 8.4 to 13.5 MeV (n8) (1969AN06). See also (1965BL07, 1967WI1H, 1971TH1D) and (1969SC1H; theor.). See also 19F.

31. 18O(3He, t)18F Qm = -1.674

At E(3He) = 16 MeV, the triton spectrum is dominated by strong groups to the ground and 0.94 MeV excited states and to the 0+ and 2+; T = 1 states at Ex = 1.04 and 3.06 MeV. Angular distributions have been measured and analyzed by DWBA for the tritons corresponding to these states and to 18F*(1.08, 1.13, 1.70, 2.10, 3.13, 3.36, 3.72, 3.79, 3.84, 4.12, 4.23, 4.36, 4.40, 4.66, 4.74). The angular distributions are consistent with the Jπ assignments shown in Table 18.14 (in PDF or PS), except for the distribution to 18F*(1.04) (1970DU08). At E(3He) = 17.3 MeV, angular distributions to 18F states with Ex < 4 MeV have been analyzed using DWBA and a two-body interaction between the incident and target nucleons. An exact coupled-channel calculation was also made for the transition to 18F*(1.04) (1968HA30, 1969HA1U, 1969MA1G). See also (1971HE1F).

32. 18Ne(β+)18F Qm = 4.447

The decay is to 18F*(0, 1.04, 1.70): see Table 18.21 (in PDF or PS) for the branching ratios and log ft values. See also 18Ne.

33. 19F(γ, n)18F Qm = -10.431

See 19F.

34. 19F(n, 2n)18F Qm = -10.431

See 20F.

35. (a) 19F(p, d)18F Qm = -8.206
(b) 19F(p, pn)18F Qm = -10.431

Angular distributions have been measured of the ground state deuterons at Ep = 16 and 18 (1967AN1B, 1968AN1A, 1971AN1B), 17.5 (1969HA1T), 18 (1956RE04), 18.6 (1961BE12), 30.3 (1967DI1C) and 155.6 MeV (1966BA44): ln = 0. (1969HA1T) also reports angular distributions at Ep = 17.5 MeV to the 18F states at Ex = 0.94 [ln = 2], 1.04 [0], 1.08 [1], 1.13, 1.70 [0], 2.10 [(1)], 2.53 [2], 3.06 [2], 3.13 [1], 3.36 [2], 3.8 (unresolved), 4.12, 4.23, 4.36 + 4.40, 4.66 and 5.6 MeV. Spectroscopic factors are also listed. Similar results are reported by (1967AN1B, 1968AN1A, 1971AN1B). See also (1961BE12, 1966BA44). See also (1961LE1A, 1962CO17) and (1969BE1T, 1969DO08; theor.). For reaction (b), see (1968DE21).

36. 19F(d, t)18F Qm = -4.173

Angular distributions of triton groups are reported at Ed = 8.9 MeV (1957EL12; t0, t1, t3) and 14.8 MeV (1959HA1E, 1960HA22; t0). See also (1959VL23) and (1963DA1B, 1963OG1A, 1964DA1D, 1964EL1B; theor.).

37. 19F(3He, α)18F Qm = 10.147

At E(3He) = 5.9 MeV, 41 α-particle groups have been observed, corresponding to the ground state of 18F and to excited states with Ex < 7.5 MeV (1959HI67): see Table 18.22 (in PDF or PS). Angular distributions of the α-particles corresponding to 18F*(3.06, 3.13) are reported by (1966MA43; E(3He) = 4.0, 6.0 and 8.0 MeV): l = 2 and 1, respectively. See also (1964BR1G, 1966HA21, 1966HO1E, 1971BA2A).

Alpha-α0 angular correlations measured in the range E(3He) = 5.0 to 6.0 MeV establish Jπ = 1- for both 18F*(5.61, 5.67): Γα/Γ ≈ 1 (1971LI27).

38. 19F(10B, 11B)18F Qm = 1.025

See (1968GA03, 1970GO1B, 1971KN05).

39. (a) 19F(14N, 15N)18F Qm = 0.403
(b) 19F(19F, 20F)18F Qm = -3.829

For reaction (a) see (1965GA1B, 1971GA13); for reaction (b) see (1971GA13).

40. 20Ne(n, t)18F Qm = -14.793

Not reported.

41. 20Ne(p, 3He)18F Qm = -15.557

At Ep = 45 MeV, 3He groups are observed to 18F*(0, 1.04, 1.70, 3.06, 6.27 ± 0.03) (1969HA38). See also (1968FA1G, 1970OL1B).

42. 20Ne(d, α)18F Qm = 2.796

At Ed = 11 MeV α-groups are observed to many states of 18F with Ex < 7 MeV. Weak or absent (each ≤ 0.3% of the total yield at 30°) are the groups corresponding to 18F*(1.04, 3.06, 4.66, 4.74, 4.96): T = 1 for these states (1968PO1B, 1969PO11). However, (1971HR1A) report a significant yield (as high as 30% of the yield to the Jπ = 2+; T = 0 state at 2.52 MeV) for the 2+; 1 state at 3.06 MeV in the range Ed = 6 to 10 MeV. The yield is particularly large in the range Ed = 6 to 8 MeV. Angular distributions are reported at 2 MeV (1966LA15; α0, α1, α2, α5, α6), 4 MeV (1964MA50; α0, α5, α6, α7, α8, α9, α10), 6.75, 7.37 and 8 MeV (1971HR1A; α7, α8, α9), and 14.7 MeV (1962TA07; α0, α1→4, α5, α6, α7). See also (1951MI1A, 1961LO10, 1964MA57) and (1966BR1G, 1966KU1D, 1969DE29).
43. 21Ne(p, α)18F Qm = -1.740

Not reported.