
^{18}F (1972AJ02)(See Energy Level Diagrams for ^{18}F) 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, 1967VA31, 1967WO1C, 1968BA2H, 1968BE1T, 1968DE1M, 1968EL1C, 1968GU1E, 1968JO1C, 1968KA1C, 1968KU1E, 1968LE02, 1968MU1B, 1968PE16, 1968VA24, 1969DE16, 1969GA1Q, 1969KA29, 1969MU09, 1969OS01, 1969RA28, 1969WA1F, 1970BA1Z, 1970EL08, 1970PR1D, 1971BA14, 1971BO21, 1971EL07, 1971LO23, 1971PR16, 1972DE05, 1972KA01, 1972LE1L). Reactions involving pions: (1968BE1F). Complex reactions involving ^{18}F: (1965LO1D, 1966LA1G, 1967AU1B, 1967WI16, 1967WI20, 1968MO1C, 1968SH26, 1968ST1L, 1969FE04, 1969KR21, 1970BR13, 1970FA01, 1970FE05, 1970KO43, 1970KR12, 1970KR1C, 1970MO38, 1971AR02). Ground state: (1970WA1T, 1971GU21, 1971WI01, 1972LE1L).
The positron decay is entirely to the ground state if ^{18}O [J^{π} = 0^{+}; T = 1]: E_{β}(max) = 635 ± 2 keV (1964HO28). See also (1959AJ76). The halflife 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 ^{18}O(0) is allowed indicates J^{π} = 1^{+} for ^{18}F(0). The ratio ε_{K}/β^{+} = 0.030 ± 0.002 (1956DR38). See also (1959PE1B, 1966KU1F, 1968DA1J, 1968LE02, 1970MC23, 1971BL12, 1971DE1E, 1971VA1C, 1971WI18; theor.).
Cross section measurements have been carried out in the range E(^{6}Li) = 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(^{6}Li) = 4 MeV due to Coulomb barrier effects. At higher energies, Ericsontype 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 isospinforbidden α_{1} group [to ^{14}N*(2.31), J^{π} = 0^{+}; T = 1] shows an energy dependence very unlike those for the α_{0} and α_{2} 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 α_{1} group is two orders of magnitude lower than those for the α_{0} or α_{2} groups (1965CA06, 1967DZ01). See also (1968NO1C; theor.). For angular distribution studies see ^{16}O and ^{17}O in (1971AJ02) and ^{14}N in (1970AJ04).
See (1957NO17, 1961NO05) and ^{19}F.
See (1962CH01).
Resonances have been observed at E_{α} = 0.56, 1.14, 1.40, 1.53, 1.62, 2.35, 2.77 and 2.88 MeV, corresponding to ^{18}F* = 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 (1969AL13). Capture resonances are not observed corresponding to ^{18}F*(4.66, 4.96), (2J + 1)Γ_{α}Γ_{γ}/Γ < 2 × 10^{5} and < 0.5 × 10^{4} eV, respectively (1971CO27). The branching ratios for ^{18}F*(5.30, 5.61, 5.68, 6.57) are displayed in Table 18.14 (in PDF or PS). The sequence of the ^{18}F states with E_{x} = 1.70 [J^{π} = 1^{+}], 2.53 [2^{+}], 3.36 [3^{+}], 5.30 [4^{+}] and 6.57 MeV [5^{+}] as well as the enhanced E2 strengths of the γtransitions show that these states can be considered to be members of a predominantly 4p2h K^{π} = 1^{+} rotational band. ^{18}F*(3.36) is found to have J = 3 (1971RO25). The M1 transitions between the J^{π} = 1^{} states at E_{x} = 5.61 and 5.68 MeV and ^{18}F*(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 E_{x} = 1.04 and 3.06 MeV, implying T = 0. This result is in agreement with ^{18}F*(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 nonresonant S factor for this reaction, S ≤ 1.5 × 10^{6} keV · b (1968PA10), ≈ 0.7 MeV · b (1971CO27). See also (1966IB1A, 1971CO1G).
The total cross section ratios of ^{14}N(α, n)^{17}F(0.50)/^{14}N(α, p)^{17}O(0.87) were measured for E_{α} = 7 to 12 MeV: major maxima are observed at E_{α} = 8.12, 9.5, 10.07 and 11.52 MeV. Symmetric angular distributions at three of these maxima lead to J^{π} = (2^{}), (2^{}, 3) and (2^{}, 3^{+}) at E_{x} = 10.73, 12.25 and 13.36 MeV. These states are primarily T = 0 (1969SC21): see Table 18.13 (in PDF or PS).
Observed resonances are displayed in Table 18.13 (in PDF or PS) (1953HE58, 1958HE54, 1958KA32). Excitation functions showing a number of structures have been measured for E_{α} = 10 to 25 MeV (p_{0}, p_{1}), 13 to 25 MeV (p_{2}) and 15 to 25 MeV (p_{3}) (1970ZE01). See also (1961YA02).
Observed amomalies in the elastic scattering are exhibited in Table 18.13 (in PDF or PS) (1939BR1A, 1939DE1A, 1953HE58, 1958HE54, 1958HE56, 1958KA32, 1961SI09, 1962JO14, 1970TO03). Resonances in the α_{1} (isospin "forbidden") and α_{2} yield are also displayed (1970TO03). See also (1966CH1E). Excitation functions have recently been reported for E_{α} = 1.0 to 2.4 MeV (1961SI09; α_{0}), 10.2 to 18.3 MeV (1970TO03; α_{0}, α_{1}, α_{2}), 15 to 23 MeV (1962JO14; α_{0}) and 18.2 to 23.5 MeV (1970CH1D; α_{1}). See also (1963NO1B, 1967BO1M, 1969FE10). In the range E_{α} = 10.2 to 17.3 MeV compound nucleus formation dominates the α_{0}, α_{1} and α_{2} channels. The α_{1} channel [to the J^{π} = 0^{+}; T = 1 state at 2.31 MeV] displays relatively isolated resonances which imply ^{18}F states with large isospin impurities [≈ 10  25%]. Comparison of this work with the results from ^{16}O(d, α_{1}) [reaction 16] suggests that the same ^{18}F 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, 1968JU04, 1970BA48, 1970JA1Q, 1970JU05). For reaction (c), see (1971TH03) and reaction 16. See also (1970VI02) and ^{14}N in (1970AJ04).
Angular distributions have been measured for E(^{6}Li) = 5.3 to 6.0 MeV (1968RI13; d_{0}, d_{1→4}).
At E(^{7}Li) = 15 MeV, triton groups are observed to the known T = 0 states with E_{x} < 7.4 MeV: the T = 1 states are not excited although such transitions are not forbidden in principle, suggesting a direct αtransfer mechanism. The transitions to ^{18}F*(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 ^{16}O(^{3}He, p)^{18}F and ^{17}O(^{3}He, d)^{18}F) are predominantly of a 4p2h nature and are excited by transfer of four nucleons into the (2s, 1d) shell (1968MI09). [See also reaction 5]. See also (1968OG1A).
See (1966AD07).
The capture cross section rises from 0.1 μb at E_{d} = 0.4 MeV to 25 μb at 3.5 MeV: Γ_{γ} over this range is ≈ 2 eV. The results can be interpreted satisfactorily in terms of compound nucleus formation (1965OW01). See also (1969AL13) and Table 18.16 (in PDF or PS).
Excitation functions have been measured for the n_{0} and n_{1} 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 ^{18}F is displayed in Table 18.17 (in PDF or PS) (1955MA85, 1961DI06, 1968MA1C). The coherence energy determined from the yield for E_{d} = 4.5 to 6.0 MeV is 70 keV for n_{0} and 67 keV for n_{1} (1970DA14). See also ^{17}F in (1971AJ02). For polarization measurements see (1971AN1A, 1971TH10) and Table 18.16 (in PDF or PS). For reaction (b) see (1968CU04).
Excitation functions have been reported recently for several proton groups up to E_{d} = 13.0 MeV: see Table 18.16 (in PDF or PS) (1959LO59, 1961LO1C, 1962CA20, 1963AM1A, 1963SE12, 1964AM1A, 1964KI05, 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 p_{0}, 63 keV for p_{1} and 62 keV for p_{3} in the range E_{d} = 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 E_{d} = 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 ^{17}O in (1971AJ02).
The yield of elastically scattered deuterons has been measured for E_{d} ≤ 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 ^{18}F states: for these see Table 18.17 (in PDF or PS) (1956BE1B, 1963AM1A, 1964AM1A, 1968MA53). See also (1963DO1B, 1966AL09, 1970VE06, 1971GA1D, 1971SC1Q) and ^{16}O in (1971AJ02). For polarization measurements, see (1969CO12, 1970CO1P, 1971KO21) and Table 18.16 (in PDF or PS).
The yields of various groups of αparticles have been measured for E_{d} ≤ 20 MeV: see Table 18.16 (in PDF or PS) (1960AM03, 1962CA20, 1963AM1A, 1963SE12, 1963YA1B, 1964AM1A, 1964KI05, 1965LO03, 1965MA59, 1965SA18, 1967TH1E, 1968DI06, 1968JO07, 1968TH1J, 1969AL13, 1969CO12, 1969JO09, 1969JO1M, 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 ^{18}F: see Table 18.17 (in PDF or PS) (1956BR36, 1957BA14, 1960AM03, 1963AM1A, 1964AM1A, 1965MA59, 1968JO07, 1969JO09, 1969JO1C, 1970JO1C, 1971JO11). See also (1970JO1F). A detailed study by (1970JO1C) of the isospinforbidden α_{1} 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 < E_{x} < 15.5 MeV (1968JO07). For the isospinforbidden α_{1} yield, virtually all the observed levels overlap several others of the same spin and parity in the tail of the resonance. The α_{1} yield has a smaller cross section than the yield of ^{14}N(α, α_{1})^{14}N at the same E_{x} in ^{18}F [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 ^{18}F at high E_{x} (1970JO1C). For polarization studies, see (1970PR1C, 1971KE1E). See also ^{14}N in (1970AJ04). Very accurate cross section measurements of the ^{16}O(d, α)^{14}N reaction and of its inverse, ^{14}N(α, d)^{16}O, are consistent with the principle of detailed balance. The lowest uncertainty was ± 0.5%. An upper limit of 0.2% is assigned to the timereversal noninvariant part of the reaction amplitudes (1971TH03).
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 ΔE_{x} (1.13 → 0.94) = 194 ± 1 keV: E_{x} of ^{18}F*(1.13) is then 1131.0 ± 1 keV [based on E_{x} = 937.0 ± 0.2 keV]. See also (1967WA1C) and (1959AJ76).
Excitation energies derived from measurements of proton spectra (1959HI67, 1959YO25, 1967MA1G, 1968GR1G, 1968GR1H, 1968MA33) and of γrays (1960RA18, 1961DU02, 1965CH10, 1967WA06) are displayed in Table 18.18 (in PDF or PS). Angular distributions of proton groups have been obtained at E(^{3}He) = 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 lassignments shown in Table 18.18 (in PDF or PS). (1960JA11) have compared the angular distribution they obtained for the ^{16}O(t, p)^{18}O reaction to ^{18}O(0) with the angular distributions obtained by (1959HI74) for ^{18}F*(1.04, 1.08) in this reaction. It is clearly ^{18}F*(1.04) which is the analog to the ground state of ^{18}O: J^{π} is then 0^{+} and T = 1. The magnetic moment of ^{18}F*(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 shellmodel predictions for a 5^{+} state remaining from 1d^{2}_{5/2} (1967PO09). The γdecay 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 γray 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 lvalues shown in Table 18.18 (in PDF or PS) lead to the J^{π} assignments displayed in Table 18.14 (in PDF or PS). See also (1963HI06). The linear polarization of the 2.10 MeV γray [2.10 → 0], together with the mixing ratio obtained by (1967GO07), leads to an assignment of negative parity to ^{18}F*(2.10), and also to ^{18}F*(1.08). The latter results from the value of τ_{m} for ^{18}F*(2.10) and the observation of a P_{4}(cos θ) term in the 2.10 → 1.08 transition (1967PO02). See also (1964MA57, 1966AG1B, 1970CA28), (1959FA1A) and (1960NE1A; theor.).
At E_{α} = 40 to 52 MeV, deuteron spectra are dominated by the groups to ^{18}F*(1.13), J^{π} = 5^{+} [1d^{2}_{5/2} configuration] (1962HA40, 1966RI04, 1967MA1G, 1968MA33). Many other states of ^{18}F 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.).
Angular distributions of the αparticles to the ground state of ^{18}F have been measured at E(^{6}Li) = 5.5 to 13.3 MeV (1968GR1H, 1968GR22) and at 26 MeV (1969DA19). The lifetime of ^{18}F*(4.36) is < 0.61 psec (1969TH01): the γray energy for the transition 4.36 → 3.06, E_{γ} = 1297.4 ± 2.5 keV. Assuming E_{x} = 3.0598, the energy of ^{18}F*(4.36), E_{x} = 4.357 ± 0.004 MeV (1969TH01). See also (1967CA1D).
See (1966GA10, 1969BR1D, 1969RO1G, 1970AN1D).
The yield of 0.94 MeV γrays (γ_{1}) has been measured for E_{p} = 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 γrays (γ_{2}) is observed, corresponding to ^{18}F*(6.14) (1969ZA1C, 1971SE1H). A study of this resonance shows that ^{18}F*(6.14) has J^{π} = 0^{+}. The parity of ^{18}F*(3.72) is found to be even (1970RO1F). Branching ratios for the decay of ^{18}F* states with 6.09 < E_{x} < 6.87 MeV are displayed in Table 18.15 (in PDF or PS). DSAM measurements show τ_{m} < 15 fsec for these states. From the γdecay of the resonant states, accurate excitation energies have been determined for a number of lowlying states: E_{x} = 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).
The yields of n_{0}, measured for E_{p} = 7 to 13.5 MeV, and of n_{1}, measured for E_{p} = 7 to 12.5 MeV, show some gross structures (1969AN06). See also (1965BL07).
The elastic scattering has been studied for E_{p} = 0.5 to 1.33 MeV (1971SE1J) and for E_{p} = 11.0 to 13.0 MeV (1967AL06): observed anomalies are displayed in Table 18.20 (in PDF or PS) (1971SE1J).
The yield of ground state αparticles shows a number of resonances for E_{p} = 0.49 to 3.0 MeV: see Table 18.20 (in PDF or PS) (1957AH20, 1962BR08, 1971SE1J). Astrophysical considerations are discussed by (1962BR08, 1967FO1B).
At E_{d} = 4.4 MeV angular distributions of the neutrons corresponding to ^{18}F*(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 ^{18}F*(5.61) is an order of magnitude greater than for ^{18}F*(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 ^{19}F.
At E(^{3}He) = 15 MeV, DWBA analysis of angular distributions of deuteron groups corresponding to the ground state of ^{18}F [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 ^{18}F*(4.12) may be assigned J^{π} = (2^{+}) or 3^{+}. Since l = 2 for ^{18}F*(4.66), J^{π} ≤ 5^{+}, with 4^{+} most likely (1969PO11).
Not reported.
E_{thresh.} = 2.577 ± 0.003 (1967PR04); E_{thresh.} = 2.576 ± 0.001, Q_{0} = 2.439 ± 0.001 (1969BE57). See also (1959AJ76). Gamma rays are observed with E_{γ} = 938 ± 6, 1043 ± 8 and 1082 ± 10 keV (1960RA18). See also (1968BE34). The lifetime of ^{18}F*(1.04) is 4^{+3}_{2} fsec (1967BL18). Angular distributions have been measured at E_{p} = 6.9 to 13.5 MeV (n_{0}, n_{1→4}), 6.9 to 9.25 MeV (n_{5}), 7.55 to 9.25 MeV (n_{6}), 7.95 to 9.25 MeV (n_{7}) and 8.4 to 13.5 MeV (n_{8}) (1969AN06). See also (1965BL07, 1967WI1H, 1971TH1D) and (1969SC1H; theor.). See also ^{19}F.
At E(^{3}He) = 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 E_{x} = 1.04 and 3.06 MeV. Angular distributions have been measured and analyzed by DWBA for the tritons corresponding to these states and to ^{18}F*(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 J^{π} assignments shown in Table 18.14 (in PDF or PS), except for the distribution to ^{18}F*(1.04) (1970DU08). At E(^{3}He) = 17.3 MeV, angular distributions to ^{18}F states with E_{x} < 4 MeV have been analyzed using DWBA and a twobody interaction between the incident and target nucleons. An exact coupledchannel calculation was also made for the transition to ^{18}F*(1.04) (1968HA30, 1969HA1U, 1969MA1G). See also (1971HE1F).
The decay is to ^{18}F*(0, 1.04, 1.70): see Table 18.21 (in PDF or PS) for the branching ratios and log ft values. See also ^{18}Ne.
See ^{19}F.
See ^{20}F.
Angular distributions have been measured of the ground state deuterons at E_{p} = 16 and 18 (1967AN1B, 1968AN1A, 1971AN1B), 17.5 (1969HAZD), 18 (1956RE04), 18.6 (1961BE12), 30.3 (1967DI1C) and 155.6 MeV (1966BA44): l_{n} = 0. (1969HAZD) also reports angular distributions at E_{p} = 17.5 MeV to the ^{18}F states at E_{x} = 0.94 [l_{n} = 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).
Angular distributions of triton groups are reported at E_{d} = 8.9 MeV (1957EL12; t_{0}, t_{1}, t_{3}) and 14.8 MeV (1959HA1E, 1960HA22; t_{0}). See also (1959VL23) and (1963DA1B, 1963OG1A, 1964DA1D, 1964EL1B; theor.).
At E(^{3}He) = 5.9 MeV, 41 αparticle groups have been observed, corresponding to the ground state of ^{18}F and to excited states with E_{x} < 7.5 MeV (1959HI67): see Table 18.22 (in PDF or PS). Angular distributions of the αparticles corresponding to ^{18}F*(3.06, 3.13) are reported by (1966MA43; E(^{3}He) = 4.0, 6.0 and 8.0 MeV): l = 2 and 1, respectively. See also (1964BR1G, 1966HA21, 1966HO1E, 1971BA2A). Alphaα_{0} angular correlations measured in the range E(^{3}He) = 5.0 to 6.0 MeV establish J^{π} = 1^{} for both ^{18}F*(5.61, 5.67): Γ_{α}/Γ ≈ 1 (1971LI27).
See (1968GA03, 1970GO1B, 1971KN05).
For reaction (a) see (1965GA1B, 1971GA13); for reaction (b) see (1971GA13).
Not reported.
At E_{p} = 45 MeV, ^{3}He groups are observed to ^{18}F*(0, 1.04, 1.70, 3.06, 6.27 ± 0.03) (1969HA38). See also (1968FA1G, 1970OL1B).
At E_{d} = 11 MeV αgroups are observed to many states of ^{18}F with E_{x} < 7 MeV. Weak or absent (each ≤ 0.3% of the total yield at 30°) are the groups corresponding to ^{18}F*(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 J^{π} = 2^{+}; T = 0 state at 2.52 MeV) for the 2^{+}; 1 state at 3.06 MeV in the range E_{d} = 6 to 10 MeV. The yield is particularly large in the range E_{d} = 6 to 8 MeV. Angular distributions are reported at 2 MeV (1966LA15; α_{0}, α_{1}, α_{2}, α_{5}, α_{6}), 4 MeV (1964MA50; α_{0}, α_{5}, α_{6}, α_{7}, α_{8}, α_{9}, α_{10}), 6.75, 7.37 and 8 MeV (1971HR1A; α_{7}, α_{8}, α_{9}), and 14.7 MeV (1962TA07; α_{0}, α_{1→4}, α_{5}, α_{6}, α_{7}). See also (1951MI1A, 1961LO10, 1964MA57) and (1966BR1G, 1966KU1D, 1969DE29).
Not reported.
