(See Energy Level Diagrams for 17F)
Other topics: (1970RY04, 1970SI1J, 1971AU02, 1971SE1C, 1971NG01, 1972BA25, 1972CA37, 1972CH16, 1972LE1L, 1972SH32, 1973DE13, 1973GO1H, 1973OS1A, 1973RE17, 1973RO1R, 1974BR1E, 1974RE03, 1974SL1C, 1974VA24, 1975SH20, 1975SH1H).
Q = 0.10 ± 0.02 b (1974MI21).
The half-life of 17F is 65.2 ± 0.2 sec (1969WO09), 64.50 ± 0.25 sec (1972AL42). The mean of previous values [see Table 17.18 (in PDF or PS) in (1971AJ02)] was 66.0 ± 0.2 sec which was the value reported by (1960JA12). We adopt τ1/2 = 64.50 ± 0.25 sec, log ft = 3.488 ± 0.001 (1972AL42) but suggest that another measurement of this half-life is in order. The upper limit for the β+ decay to 17O*(0.87) is < 3.4 × 10-4 per decay (1969GA05) [log ft > 5.6]. See also (1970KO41, 1970MC23, 1971BH04, 1971LI1H, 1971WI18, 1972WI28, 1972WI1C, 1973LA03, 1973MU1D, 1973WI04, 1973WI11, 1974WI1M, 1975BA59, 1975BL1G, 1975KR14, 1975WI1E; theor.).
The yield of γ0+1 at 90° shows resonant structures at E(3He) = 4.35 ± 0.05, 5.36 ± 0.05, 5.7 and 6.28 ± 0.05 MeV, corresponding to 17F*(19.42, 20.25, 20.5, 21.01), respectively. Angular distribution measurements are consistent with Jπ = 5/2+, 7/2-, (3/2-) and 1/2+ for these states; the widths of the three highest ones are ≈ 350, 210 and 280 keV (1973MO1C).
Excitation functions for p0 have been measured for E(3He) = 2.5 to 5.5 MeV (1963GO09), 3.5 to 18 MeV (1972BI01) and 5.5 to 10.5 MeV (1971GU22; also p1+2, p3, p4): some large structures are observed. The elastic scattering of 3He (reaction (e)) has been studied for E(3He) = 4 to 7 MeV: there is some evidence in the excitation functions of the resonances reported in (3He, γ) (reaction 4) (1973MO1C). The yields of α0, α1 and α2+3 (reaction (f)) in the range E(3He) = 2.5 to 8.5 MeV show broad un-correlated fluctuations, except for a structure at E(3He) = 4.5 MeV (1970KN01). However, a study of α0 [E(3He) = 3.5 to 7 MeV] shows, at θ = 150°, strong structures corresponding to the resonances at E(3He) = 4.35 and 5.36 MeV reported in (3He, γ): their analysis suggests Γ = 300 and 350 keV (1973MO1C). For reaction (d) see (1973AD02). See also (1971ADZZ), (1971AJ02, 1974LO1B), (1974FA1A; theor.), 16O, 16F, and 13N, 14N and 15O in (1976AJ04).
At E(6Li) = 18 MeV the triton groups in this reaction and the 3He groups in the mirror reaction have been compared. 17F*(3.86, 5.22, 5.67 + 5.68) are strongly excited. A state at Ex = 5.220 ± 0.010 MeV is identified as the mirror state to 17O*(5.22): its probable Jπ is 9/2-. 17F*(0, 0.50, 3.10, 4.70, 5.52, 5.82, 6.04, 6.70) are also populated (1973BI01). See also (1972BA1P).
Angular distributions have been measured for the neutron groups to 17F*(0, 0.50, 3.10, 3.86) at E(3He) = 3.8 and 4.8 MeV and to 17F*(4.70, 5.52, 5.68) at the higher energy. The population of a state at Ex = 5.179 ± 0.020 MeV and of 17F*(6.04, 6.70, 7.03, 7.36, 8.08) is also reported. 17F*(5.18) probably has Jπ = 3/2+ or 9/2+ (1972TH07, 1973ET01). Neutron groups have also been reported to 17F states at Ex = 11.195 ± 0.007, 12.540 ± 0.010 and 13.059 MeV, with Γ < 20, < 25 and < 25 keV, respectively. Angular distributions at E(3He) = 10.36 and 11.88 MeV lead to Jπ = 1/2- for 17F*(11.20) [L = 0], 3/2- or 5/2- for 17F*(12.54) and (3/2-, 5/2-) for 17F*(13.06). These three states are probably the first three T = 3/2 states in 17F (1969AD02). The branching ratios for transitions to 16O*(0, 6.05, 6.13) for 17F*(11.20) and for the analog T = 3/2 state in 17O are displayed in Table 17.11 (in PDF or PS): the ratios of the reduced widths are quite different in the two mirror nuclei (1970MC02, 1973AD02).
At low energies the direct capture to 17F*(0, 0.50) has been observed: see (1971AJ02) for a summary of the earlier measurements and (1973RO34: 0.3 - 3.1 MeV), (1975CH34: 0.85 - 2.55 MeV). Extrapolation of cross section data leads to S(0) = 9 keV · b (1973RO34), 7.45 keV · b (1971BA1A). See also (1973CL1E, 1975CH34). An anomaly is observed at Ep = 2.66 MeV [17F*(3.10)] in the yield of the γ-ray transition to 17F*(0.50): Γγ = 12 ± 2 meV; C2S = 0.90 and 1.00, respectively, for 17F*(0, 0.50) (1973RO34). Another resonance is observed at Ep = 3.47 MeV [17F*(3.86)]: angular distributions of the γ-rays are characteristic of an almost pure dipole transition. The data lead to Jπ = 5/2-, Γ < 1.5 keV, Γγ = 0.11 ± 0.02 eV, τm = 6 ± 1 fsec (1963SE14). For 17F*(0.50), τm = 445 ± 22 psec (1960KA10).
Five resonances corresponding to T = 3/2 states are observed in the γ1 and γ0 + γ1 yields: see Table 17.18 (in PDF or PS) for the reported parameters (1975HA06). The lowest T = 3/2 states of even parity at Ex = 13.27 and 14.02 MeV [Jπ = (1/2+) and 5/2+] (see Table 17.19 (in PDF or PS)) are not observed here: Γγ ≤ 7 and ≤ 11.8 eV, respectively (1975HA06). The (E1) values for the T = 3/2 states are in good agreement with shell model 2p - 1h calculations using realistic Kuo-Brown interaction matrix elements (1975HA06).
The (γ0 + γ1) yield at 90° has been studied for Ep = 15.75 to 31.66 MeV: it shows the giant dipole resonance centered at Ex = 22 MeV with a width of ≈ 5 MeV and a pigmy resonance centered at 17.5 MeV. The integrated strength of the, mainly T = 1/2, giant resonance is 10 MeV · mb: the observed strength distribution is in good agreement with odd parity 2p - 1h, 1p excitation calculations. The pigmy resonance is due to f7/2 → d5/2: the main f7/2 strength lies in two states at Ex = 16.9 and 18.0 MeV (1975HA07). See also (1971JO1D).
Yield curves for elastic protons, protons scattered to 16O*(6.05, 6.13, 6.92, 7.12, 8.87) and for γ-rays from 16O*(6.13, 6.92) have been studied at many energies up to Ep = 46 MeV: see Table 17.19 (in PDF or PS) in (1971AJ02) for a listing of the earlier measurements and (1975CH34: p0, 171.5c.m., Ep = 0.39 to 1.99 MeV), (1971AU04: p1+2, p5; σt; Ep = 17.0 to 46.1 MeV) and (1969BU1B, 1971BU05: p0, p1+2, p5; Ep = 21.3 to 38.5 MeV). The observed resonances are displayed in Table 17.19 (in PDF or PS). Phase-shift analyses of elastic scattering polarization and cross section data have led to an increased understanding of the T = 1/2 states of 17F (1971PR05, 1975HI02) and the work of (1974SK02, 1976HI09) has fixed the characteristics of the first seven T = 3/2 states of 17F. (1974SK02) has studied the isospin multiplet mass equation by comparing analog T = 3/2 states in A = 17. See also (1976IK01).
Other polarization measurements are reported at Ep = 3.47 and 6.83 MeV (1974DA04; p0), 20 MeV (1974PL05, 1976PL1C; p3, p4, p6, p7), 30.3 MeV (1976DE12; p0, p2, p3, p5), 30.4 MeV (1972GR02; p0, p5), 30.4 to 39.9 MeV (1976LE16; p5) and 49.4 MeV (1970CL10; p0). See also (1971KL03). Total reaction cross section measurements are reported at Ep = 18.8 to 47.7 MeV (1975CA26), 21 to 43 MeV (1975SL02), and 231, 345, 464 and 552 MeV (1972RE06). See also (1971BE1D, 1971CR1A, 1973GO27, 1976WU1A).
See also 16O, (1971AJ02, 1971PA1H), (1975ME1E; astrophys. considerations) and (1972GE07, 1972PH06, 1973CL01, 1973MO1E, 1973RU07, 1973TH02, 1974SI13, 1975BA05, 1975CA05, 1975GE08, 1975SM01, 1975TA1A, 1975TH03, 1975TH12, 1976CO2A; theor.).
The excitation function for d0 at θ = 70° has been measured for Ep = 21 to 38.5 MeV: a strong resonance is observed at Ep ≈ 24 MeV (1969BU1B, 1971BU05): see Table 17.19 (in PDF or PS). For polarization measurements see (1967CH15; 30.3 MeV; d0, d3). See also 15O in (1976AJ04) and (1970DE38, 1971SA1D; theor.).
The excitation function at θ = 70° for tritons (reaction (a)) has been measured for Ep = 32 to 39.5 MeV: no structure is observed (1969BU1B, 1971BU05). Differential cross sections and analyzing powers have been studied at Ep = 43.8 MeV for the transitions to 14O*(0, 5.17, 6.29, 6.59, 7.78, 9.72) and 14N*(0, 2.31, 3.95, 5.11, 7.03, 9.17): attempts to fit the analyzing powers with zero-range DWBA were only successful for the first pair of analog states [14Og.s., 14N*(2.31)] (1974MA12). For other polarization measurements see (1970NE17: Ep = 49.5 MeV; t0, 3He to 14N*(0, 2.31)). See also (1975MI01, 1976PL1C), (1971AJ02, 1972HA1X, 1976DA1K) and 14N and 14O in (1976AJ04).
Excitation functions of various α-groups and activation functions have been measured from threshold to Ep = 44 MeV: see Table 17.19 (in PDF or PS) in (1971AJ02) for the earlier work and (1973MC12, 1973MC1H: 5.6 to 7.7 MeV; σt), (1973NE12: 5.7 to 10.5 MeV; σt for α0). (1971GU23: 19 to 44 MeV; σt for α0, α1, α2+3, α4) and (1969BU1B, 1971BU05: 21.5 to 38.5 MeV). In addition, the work of (1974SK02, 1976HI09) has established the parameters of the first seven T = 3/2 states of 17F: see Table 17.19 (in PDF or PS). No other resonances corresponding to T = 3/2 states have been observed below Ex = 16.21 MeV (1974SK02). Resonances corresponding to T = 1/2 states are also reported in Table 17.19 (in PDF or PS). Some broad structures have been reported above Ep ≈ 15 MeV: see (1971AJ02) and (1971BU05, 1971GU23): particularly strong peaks appear at Ep ≈ 22 and 25.5 MeV (1971BU05).
This reaction is involved in explosive oxygen burning in stars: cross sections, and reaction rates determined as a function of the temperature of the star are discussed in (1973NE12, 1973MC12, 1973WO1C). See also (1973AR1E).
Slow neutron thresholds have been observed corresponding to the ground and first excited states of 17F: see (1971AJ02). The Ex of 17F*(0.50) is 495.33 ± 0.10 keV (1966AL10; from γ-measurement); τm = 407 ± 9 psec (1964BE15). Neutron groups have been observed corresponding to 17F*(0, 0.50, 3.10, 3.86, 4.70). Angular measurements have been obtained for the n0 and n1 groups (lp = 2 and 0; Jπ = 5/2+ and 1/2+, respectively) for Ed ≤ 12 MeV: see Table 17.21 (in PDF or PS) in (1971AJ02). For polarization measurements see (1972AN1G; n0, n1; Ed = 3 - 4 MeV). See also (1971TH1E, 1976FR13), (1976LO1B; applied) and (1972DZ1A, 1976SH13; theor.).
At E(3He) = 18 MeV, angular distributions of the deuterons to 17F*(0, 0.50, 3.104 ± 0.003, 3.857 ± 0.004) have been measured. The spectroscopic factors for 17F*(0, 0.50) are 0.94 and 0.83. Two step processes appear to be involved in the excitation of 17F*(3.10, 3.86) (1975FO16). See also (1972PR1D). For reaction (b) see (1967HO14). See also (1971AJ02).
The angular distribution involving 17Fg.s. has been measured at E(7Li) = 36 MeV (1973SC26).
Angular distributions have been measured at E(10B) = 100 MeV for the transitions to 17F*(0 + 0.50, 5.1, 8.1) (1975NA15).
Angular distributions of the n0 and n1 groups have been obtained for Ep = 6.95 to 13.50 MeV (n0) and 6.95 to 12.45 MeV (n1). There appears to be collective enhancement in the L = 2 transition to 17F*(0.5). A large spin-flip term in the effective two-body force is necessary to account for the strength of the ground state transition (1969AN06). See also 18F in (1978AJ03).
At E(3He) = 17.3 MeV, angular distributions have been obtained for the tritons corresponding to 17F*(0, 0.50). The data have been analyzed using DWBA and a two-body interaction between the incident and target nucleons. An exact coupled-channel-equation calculation was also made for the ground state transition (1968HA30). See also (1971AJ02).
Angular distributions have been measured for the t0, t1, t2 and t3 groups at Ep = 22.8 MeV (1963HO24), 42.4 MeV (1974NE03) and 45 MeV (1972HU1B). See also (1968AN1A, 1972PR1D), (1971AJ02) and 20Ne in (1978AJ03).