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17F (1959AJ76)
(See Energy Level Diagram for 17F)
GENERAL: See also Table 17.6 [Table of Energy Levels] (in PDF or PS).
Theory: See (1956KA1C, 1958BA32).
| 1. 17F(β+)17O | Qm = 2.767 |
The decay proceeds to the ground state of 17O: Eβ+(max) = 1.748 ± 0.006 MeV. The spectrum has the allowed shape down to 570 keV, and an upper limit of 1% is placed on possible transitions to the 875 keV state of 17O (1954WO20). The weighted mean value of the half-life from the determinations of (1949BR27, 1951LA15, 1954KO54, 1954WA1A, 1954WO20, 1958AR15) is 66.0 ± 0.3 sec. Log ft = 3.38. See also (1958BE1G; theor.).
| 2. 14N(α, n)17F | Qm = -4.747 |
| Q0 = -4.76 ± 0.07 (1956DO1C). |
Slow neutron threshold and proton recoil measurements indicate an excited state at 0.53 ± 0.04 MeV (1956DO1C).
| 3. 15N(3He, n)17F | Qm = 4.989 |
Not observed.
| 4. 16O(p, γ)17F | Qm = 0.596 |
Non-resonant capture has been studied for Ep = 0.8 to 2.1 MeV. This work indicates, in addition to the direct ground-state transition (γ1), a transition (γ2) to a state of 17F at 487 ± 10 keV which then radiates (γ3) to the ground state. The ratio of γ2 to γ1 is ≈ 10 over the energy region studied. The γ1 and γ3 radiations are approximately isotropic, while γ2 has an almost pure (sin2θ) distribution (Ep = 1.0 to 1.9 MeV). At Ep = 1.35 MeV, the cross section for production of γ2 radiation is 6 ± 3 μb. The fact that most transitions involve the 0.50 MeV state (γ2) indicates that the non-resonant yield is not to be attributed to this state; it is suggested that direct, one-stage capture is involved (1954WA1A).
The relative 17F activity has been measured from Ep = 1.1 to 4.1 MeV by (1951LA15). The cross section increases almost linearly with proton energy from 1.1 to 3.75 MeV, except for a sharp resonance at 3.47 MeV. There is some indication of a broad resonance at 3.99 MeV (1951LA15, 1951LA1B).
For Ep = 140 to 170 keV, the cross section varies from 0.46 to 2.34 × 10-10 b (1958HE57). At Ep = 616 keV, σ = 0.29 ± 0.03 μb; both the magnitude of the cross section and the character of the excitation function from Ep = 275 to 616 keV are consistent with a direct capture process (1959TA03). See also (1953WI1A, 1957BU66, 1958LI1A, 1959CH1F).
The excitation energy of the first level of 17F is 495 ± 15 keV (1958HO97), 505 ± 10 keV (1957LE28). The lifetime of 17F*(0.5) is τm = (2.5 ± 0.7) × 10-10 sec (1957LE28), (3.5 ± 1.5) × 10-10 sec (1958HO97). Using the weighted mean, 2.9 × 10-10 sec, the ration τm 17F*(0.5)/τm 17O*(0.87) = 1.2 (1958HO97): see 16O(d, p)17O and (1958BA32).
| 5. 16O(p, n)16F | Qm = -16.41 | Eb = 0.596 |
See (1958TA03).
| 6. 16O(p, p)16O | Eb = 0.596 |
Observed anomalies in the scattering are exhibited in Table 17.7 [Levels of 17F from 16O(p, p)16O] (in PDF or PS). The low energy scattering data require a large s-wave phase shift, probably reflecting the bound level at 17F*(0.55), and a relatively large d-wave shift (1951LA1B, 1953EP1A). A study of proton polarization for Ep = 2.5 to 3.0 MeV confirms the assignment J = 1/2- to 17F*(3.10) and excludes 1/2+, 3/2- (1957SO1B). A phase shift analysis for Ep = 3 to 7 MeV requires four broad resonances corresponding to 17F*(4.5) (P3/2), *(4.6) (D3/2), *(5.15) (S1/2) and *(6.65) MeV (S1/2). Eight additional sharp resonances are found in this region (1954SE1B: see Table 17.7 [Levels of 17F from 16O(p, p)16O] (in PDF or PS)): however, the curves of (1956HE1B) show no evidence of fine structure from Ep = 2.5 to 5.5 MeV beyond that indicated in column A of Table 17.7 [Levels of 17F from 16O(p, p)16O] (in PDF or PS). See also 16O(d, n)17F.
Scattering at Ep > 10 MeV appears to be dominated by optical model effects: see 16O.
| 7. 16O(p, α)13N | Qm = -5.208 | Eb = 0.596 |
See (1958WH34).
| 8. 16O(d, n)17F | Qm = -1.631 |
| Ethresh. = 1.830 ± 0.004; Q0 = -1.626 ± 0.004 (1955MA85). |
Neutron groups have been observed corresponding to 17F*(0, 0.536 ± 0.010 (1951AJ1B), 0.53 ± 0.06 (1951EL1A, 1953MI10), 3.03 ± 0.06, and 4.74 ± 0.07 MeV (1957GR1A)). Angular distributions of the n0 and n1 groups, analyzed by stripping theory, indicate J = 3/2+ or 5/2+ for the ground state and J = 1/2+ for the first excited state (1951AJ1B, 1951EL1A, 1953MI10). The ratio of the reduced widths of the 17F and 17O ground states is 1.30 (1956CA1D). The width of the neutron group corresponding to 17F*(4.74) is < 90 keV, considerably smaller than is reported in 16O(p, p)16O (1957GR1A).
Slow neutron thresholds have been observed corresponding to the ground and first excited states of 17F: Q1 = -2.125 ± 0.004 MeV corresponding to 17F*(499 ± 3 keV) (1955MA85). See also (1958BE03, 1958GO77).
| 9. 16O(3He, d)17F | Qm = -4.898 |
Not reported.
| 10. 16O(α, t)17F | Qm = -19.217 |
Not reported.
| 11. 17O(p, n)17F | Qm = -3.550 |
Not reported.
| 12. 17O(3He, t)17F | Qm = -2.785 |
Not reported.
| 13. 19F(γ, 2n)17F | Qm = -19.582 |
See 19F.
| 14. 19F(p, t)17F | Qm = -11.098 |
Not reported.
| 15. 20Ne(p, α)17F | Qm = -4.158 |
Not reported.