(See Energy Level Diagrams for 19F)
Kaon capture: (AT78).
μ0.197 = +3.607 ± 0.008 nm (LE78N);
Q0.197 = -0.12 ± 0.02 b (LE78N).
The total reaction cross section has been measured for E(10B) = 2.20 to 10.43 MeV (CH79R).
For reaction (a) see (78AJ03). The yield of 18F [reaction (b)] has been determined for E(7Li) = 2.5 to 3.5 MeV (NO61). The cross sections for reaction (c), (d), (e) and (f) vary strongly over the range E(7Li) = 4 to 14 MeV but with little, if any, cross correlation. Strong fluctuations continue to E(7Li) = 25 MeV and there is some evidence of structures at higher energies: for a listing of the earlier references see (78AJ03). The excitation functions for several groups in 16O have been studied for E(12C) = 54 to 62 MeV, as has the total cross section (for residues of A > 8) for E(7Li) = 10 to 38 MeV (DE81I). See (PO76A, DR78) for reaction (g). See also (XE81; theor.), 18O here, 16O and 17O in (82AJ01), 15N in (81AJ01) and 12C in (80AJ01).
At E(9Be) = 12 - 27 MeV angular distributions are reported to 19F*(2.78) and to several unresolved groups (JA79T, JA81D). The excitation function for 19F*(2.78) has been measured for E(9Be) = 10.5 to 25.9 MeV (HU80E).
At E(11B) = 18.0 to 34.1 MeV excitation functions are reported for the transitions to 19F*(0 + 0.11 + 0.20, 1.35 + 1.46 + 1.56, 2.78) (FR79F).
For the yield of 19F for E(12C) = 24 to 62 MeV see (KO80).
Excitation functions for tritons to a number of states of 16O have been measured for E(6Li) = 20 to 32 MeV [correlated structures are not observed (CU80A)] and 24 to 26 MeV (AB82). Excitation functions for α0 have been measured for E(6Li) = 7.7 to 16.8 MeV: structures are observed but they are not correlated (CO74F). For reaction (c) see (PO76A, DR78). For fusion cross sections see (DE81F, DE81AA). See also (ME81D; theor.).
Angular distributions have been studied at E(13C) = 27.9 MeV to 19F*(0 + 0.11 + 0.20, 2.78) (BO80R).
Cross sections have been measured for E(14N) = 7 to 18 MeV (WU78C).
Resonances in the yield of γ-rays are observed below Eα = 10.4 MeV: the parameters for these are displayed in Table 19.9 (in PDF or PS). Branching ratios are shown in Table 19.7 (in PDF or PS) and τm measurements (DI77F, AN80A) in Table 19.8 (in PDF or PS). The Jπ values are shown in Table 19.9 (in PDF or PS) are based on correlation and angular distribution measurements and on branching ratio determinations.
The Ex of states involved in cascade decays are 4377 ± 1 and 4548 ± 2 keV (RO76F), 3999.6 ± 1.2 and 4031.9 ± 0.4 keV (RO73O). The Kπ = 1/2+ band involves 19F*(0.110 [1/2-], 1.46 [3/2-], 1.35 [5/2-], 4.00 [7/2-], 4.03 [9/2-], 7.16 [11/2-]) (RO73O) and possibly 19F*(8.29 [13/2-]) (UN74) [Jπ in brackets]. The situation concerning the other bands is not clear: see (72AJ02) for a discussion of the evidence for other assignments of Jπ and Kπ. 19F*(10.41) is likely to be the second 13/2+ (2s, 1d)3 state in 19F (SY76, SY78). See also (TA78S; astrophys.).
Resonances observed in the (α, α'γ) and (α, pγ) reactions (SY78) and in the elastic scattering (reaction (b)) [see (78AJ03) for references] are displayed in Table 19.10 (in PDF or PS). The elastic excitation function has been measured for Eα = 16 to 23.7 MeV by (FE77F). See also (LE79O; theor.).
At E(11B) = 115 MeV, 19F*(8.29, 8.96) [Jπ = 13/2-, 11/2-, respectively] are populated as are states at 10.4 ± 0.05, 12.26 ± 0.07, 12.67 ± 0.08, 14.9 ± 0.09, 15.4 ± 0.09, 17.4 ± 0.08, 18.6 ± 0.08 and 19.7 ± 0.08 MeV (BR79A).
At E(13C) = 105 MeV, 19F*(4.02, 8.29, 8.95, 12.26 ± 0.1, 12.65 ± 0.1, 14.8 ± 0.12) are strongly populated. 19F*(2.78) is also observed. It is suggested that 19F*(8.29, 8.95, 12.26, 12.65) have Jπ = 13/2-, 11/2-, (17/2-), (15/2-), respectively, and that 19F*(12.26, 12.66) are members of the 2N + L = 8 α-cluster band in 19F (BR79A). See also (FO77G).
For reaction (a) see (78AJ03). The excitation function for reaction (b) has been measured for Et = 0.3 to 3.7 MeV: there is evidence for a maximum at Et = 2.5 MeV. For resonances in the yields of p0, p1, α0, α1+2, see (78AJ03). The elastic yield [reaction (d)] shows a large number of resonances: their parameters are displayed in Table 19.12 (in PDF or PS). See also (CI77B), (AO81B; theor.) and 18O here.
Angular distributions have been measured at Eα = 20.1 to 40 MeV [see (78AJ03)] and at Eα = 40 MeV (VA79C: to 19F*(0 + 0.20, 2.78, 4.65): the 3p 13/2+ strength is split between 19F*(4.65, 10.42). States observed in this reaction are displayed in Table 19.12 (in PDF or PS) of (78AJ03).
This reaction (and its mirror reaction 16O(6Li, t)19Ne [see reaction 7 in 19Ne]) have been studied at E(6Li) = 24 MeV [see (78AJ03)] and at 46 MeV (MA79DD). Members of the Kπ = 1/2+ and 1/2- rotational bands have been identified: see Table 19.13 (in PDF or PS). In addition 3He groups are reported to states with Ex = 6.10, 6.92, 7.25, 8.29, 8.96, 9.7, 9.88, 10.4 [all ± 0.015], to unresolved states near 11.5, 12.7 and to states at Ex = 13.76, 14.10, 15.00, 15.56 and 18.92 [± 0.03] MeV (MA79DD). See also (FO77G).
This reaction, as well as the analog reaction [16O(10B, 7Li)19Ne] have been studied at E(10B) = 100 MeV: an attempt is made to match analog states [see reaction 8 in 19Ne] but problems of energy resolution are evident (HA76C). See also (FO77G).
The angular distribution for the transition to 8Beg.s. + 19Fg.s. has been measured at E(16O) = 60 MeV (SC72C).
For reaction (a) see 18F in (72AJ02); for reaction (b) see 18O; for reaction (e) see 15N in (70AJ04). At Ed-bar = 52 MeV polarization measurements are reported involving the groups to 16O*(6.13, 8.87, 19.19) and 16N*(0, 0.297, 6.17 + 6.36) (MA81D). See also 16N and 16O in (82AJ01).
At Eα = 47.5 MeV angular distributions have been studied to the 1/2+ --> 9/2+ and the 13/2+ members of the K = 1/2+ band [19F*(0, 0.197, 1.55, 2.78, 4.65, 5.47)], to two 11/2+ states 19F*(6.49, 7.94) [both of which are strongly populated] and to the 7/2+ state at 4.38 MeV. The reaction populates strongly only those positive-parity states that predominantly (sd)3 (FO78I, FO75G).
This reaction has recently been studied for Ep = 80 to 2200 keV by (WI80O). A large number of resonances have been investigated and Eres, total and partial widths, branching and mixing ratios and ωγ values are reported. Transition strength arguments as well as analyses of γ-ray angular distrubution data lead to Jπ assignments: see Tables 19.7 (in PDF or PS), 19.15 (in PDF or PS) and 19.16 (in PDF or PS) for a display of the results (WI80O).
In addition absolute cross sections measured for direct capture leads to C2S values for a number of states of 19F. Reduced widths and Jπ determinations lead to (WI80O) to postulate 19F*(3.91, 4.55, 4.38, 6.59, 6.50, 10.43) as the Jπ = 3/2+, 5/2+, 7/2+, 9/2+, 11/2+, 13/2+ of the Kπ = 3/2+ rotational band; 19F*(7.73 or 7.26, 6.09, 9.81, 6.92, 9.87) as the Jπ = 1/2-, 3/2-, 5/2-, 7/2- and 11/2- members of the excited Kπ = 1/2- rotational band; and 19F*(4.56, 4.68, 5.42, 6.10, 7.17) as the Jπ = 3/2-, 5/2-, 7/2-, 9/2- and 11/2- members of the Kπ = 3/2- rotational band. The direct capture transition to 19F*(7.54) indicates some isospin mixing in this 5/2+, first T = 3/2 state in 19F (WI80O).
Stellar reaction rates have also been calculated: the data cover T9 = 0.01 - 5.0. The consequences for the final termination of the CNO tri-cycle are discussed (WI80O). See also (ZI75C; astrophys.). For the earlier work see (78AJ03). See also (DI78E).
Scattering studies have been carried out for Ep = 0.6 to 16.3 MeV [see (78AJ03)], and for Ep = 3.05 to 3.5 MeV (DI78E; p1γ) and Epol. p = 6.1 to 16.6 MeV (MU79A; p0, p1). Pronounced resonant structure is evident up to Epol. p = 14 MeV (MU79A). Observed resonances are displayed in Table 19.18 (in PDF or PS). For other polarization measurements see (GL81; Epol. p = 800 MeV) and (78AJ03). See also (FA80) and 18O.
Yield measurements have been studied for Ep = 0.50 to 14 MeV [see (72AJ02)] and at Ep = 72 to 935 keV (LO79A; α0), 235 to 698 keV (MA78Q; α0) and 6.6 to 10.4 MeV (WI79K; α0): observed resonances are displayed in Table 19.18 (in PDF or PS). The stellar reaction rates have been determined for T9 = 0.008 to 2.5 (RO78B). See also (ZI75C, MA78Q; astrophys.) and (78AJ03).
Angular distributions of neutron groups corresponding to 19F states with Ex < 8.2 MeV have been measured at Ed = 3 and 4 MeV: see Table 19.18 (in PDF or PS) in (78AJ03). Gamma-ray measurements are reported here in Table 19.19 (in PDF or PS) and τm measurements in Table 19.8 (in PDF or PS). For reaction (b) see (72AJ02).
Angular distributions of the deuterons corresponding to many states of 19F have been analyzed by DWBA: the results are shown in Table 19.19 (in PDF or PS). The spectroscopic factors obtained for 19F*(7.54, 8.80), the T = 3/2, Jπ = 5/2+ and 1/2+ analogs of 19O*(0, 1.47) are in good agreement with those obtained for the 19O states in the 18O(d, p)19O reaction (FO71L). See also (HA79H) and (78AJ03).
The decay is primarily by allowed transitions to 19F*(0.197, 1.55), Jπ = 5/2+, 3/2+. Very weak branches are also observed to 19F*(0.11, 1.35, 3.91, 4.39), Jπ = 1/2-, 5/2-, 3/2+, 7/2+: see Table 19.20 (in PDF or PS). The half-life is 26.91 ± 0.08 sec: see reaction 1 in 19O. The character of the allowed decay to the 5/2+ and 3/2+ states, and the forbiddenness of the decay to the ground state of 19F are consistent with Jπ = 5/2+ for the ground state of 19O, and then with (7/2+) for 19F*(4.39): see (OL66). Gamma-ray branching ratios are displayed in Table 19.7 (in PDF or PS).
Time differential β-γ angular correlation measurements lead to a ratio +0.030 ± 0.015 for the Fermi to Gamow-Teller matrix elements (CVMF/CAMGT) for the allowed β- decay (5/2+ --> 5/2+) from 19Og.s. to 19F0.197. This leads to a value for MF (isospin-forbidden Fermi matrix element) of (4.7 ± 2.4) x 10-3. The admixture of the analog of the 19Og.s. in the 19F excited state α = (2.7 ± 1.4) x 10-3 and the effective charge-dependent matrix element |HCD| = 20 ± 10 keV (PE78E).
The cross section for (γ, Tn) has been measured for Eγ = 10.5 to 28 MeV: it shows a clear resonance at Eγ ~ 12 MeV and unresolved structures at higher energies. The integrated cross section to 29 MeV is 108 ± 7 MeV · mb (VE74D). For reports of other structures see (72AJ02, 78AJ03). See also (TH79A) and 18F. For reactions (b) and (c) see (78AJ03).
The integrated cross sections for the p0 and p1 processes at 90° for Eγ = 13.3 --> 25.4 and 15.2 --> 26.0 MeV are, respectively, 1.80 ± 0.27 and 0.50 ± 0.45 MeV · mb/sr. The (γ, p0) cross section at 90° shows broad structures at Eγ = 15.0, 17.0 and 23 MeV (TS75). For a report of other structures see (78AJ03). See also (KE79, TH79A) and 18O.
This reaction has been studied for the transition to 16Og.s. for Eγ = 18 to 23 MeV. Two peaks are observed at Eγ = 18.8 and 20.1 MeV: the angular distribution of t0 indicates Jπ = 1/2- or 3/2-, T = 1/2. The triton GDR contributes ~ 1% or the total GDR (SK74A).
The energy of the first excited state is 109.894 ± 0.005 keV; its width is (5.1 ± 0.7) x 10-7 eV. 19F*(1.46, 3.91, 7.66) are also excited. Ex = 7663 ± 4 keV for the latter. The scattering cross section is relatively small and structureless for Eγ = 14 to 30 MeV. See (78AJ03) for references.
The rms radius of 19F = 2.885 ± 0.015 fm (HA73H). At Ee = 400 MeV, 0.5 < / = q < / = 2.5 fm-1, the squared form factors have been determined for 19F*(0, 1.55, 0.197, 5.46, 2.78, 4.65) [the Jπ = 1/2+, 3/2+, 5/2+, 7/2+, 9/2+, 13/2+ members of the K = 1/2+ ground-state rotational band] as well as for 19F*(4.38) [Jπ = 7/2+]. The data are consistent for q < 1.8 fm-1 with transition strengths which were derived from a variation-after-projection, Hartree-Fock approximation (VPHF). However for the transitions to 19F*(1.55, 0.197) (q > 1.8 fm-1) the relative magnitudes of the transitions require a strong M3 component in the 5/2+ state and a weak component in the 3/2+ state, consistent with predominant L · S coupling. Including M5 and M7 strength improves the agreement with the data for 19F*(2.78, 4.65) (WI78C). The deformation parameters for the ground-state band are β2 = 0.43 ± 0.02, β4 = 0.12 ± 0.02 (OY75). Values of |M|2 adotped by P.M. Endt (private communication) are 8.9 ± 0.5 (E3), 6.9 ± 0.5 (E2) and 6.1 ± 2.4 W.u. (M5) for the g.s. transitions of 19F*(1.35, 1.55, 2.78): for other values see Table 19.20 (in PDF or PS) in (78AJ03). For reactions (b) and (c) see (78AJ03).
Angular distributions of neutron groups have been reported at En = 2.6, 14.1 and 14.2 MeV: see (72AJ02). Ex for the first six excited states of 19F, derived from γ-ray measurements, are 109.8 ± 0.2, 197.2 ± 0.2, 1345.4 ± 0.3, 1456.9 ± 1.1, 1554.0 ± 0.3 and 2775.1 ± 3.5 keV (SP68). See also (CO78Q, CO80U), (78AJ03), (NO77D; theor.) and 20F here.
Table 19.21 (in PDF or PS) displays energy levels of 19F derived from this reaction. Angular distributions of various proton groups have been measured from Ep = 4.3 to 30 MeV [see (78AJ03)] and at 35.2 MeV (FA80A; p0). The ground-state rotational band is characterized by β2 = 0.44 ± 0.04, β4 = 0.14 ± 0.04 (DE73L, DE74Q). The g of 19F*(0.197) = 1.47 ± 0.03 (KR78A). The mixing ratio for the 1.46 --> 0.11 transition (3/2- --> 1/2-; K = 1/2- band), δ(E2/M1) has been remeasured by (DI80C) to be 0.224 ± 0.040. A re-analysis of earlier experiments leads to a "best" value of 0.248 ± 0.020 for the ratio and to an E2 strength of 18.7 ± 1.9 W.u. The 1.46 --> 0 transition is pure E1 (δ = 0.01 ± 0.03) (DI80C). See Table 2 in the Introduction in this publication, and Table 19.7 (in PDF or PS). For reaction (b) see 18O. See also (KE81E, FI82), (SH78H, KR80B; applied), (PH77C, ZE79C, KO80CC; theor.) and 20Ne.
Angular distributions of elastically scattered deuterons has been measured for Ed = 2.0 to 15 MeV [see (72AJ02)] for the earlier references] and for 1.6 to 2.4 MeV (AS78). Angular distributions have also been measured for d1 --> d5 and B(Eλ) have been derived (DE70A; Ed = 15 MeV). For polarization measurements see (78AJ03). See also (AN79R).
Elastic angular distributions have been measured at Et = 2 and 7.2 MeV: see (72AJ02).
Angular distributions of elastically scattered α-particles have been measured at Eα = 19.9 to 23.3 MeV and at 38 MeV [see (72AJ02)]. Many inelastic groups have also been studied: see Table 19.22 (in PDF or PS) in (78AJ03).
The energy of the γ-ray from 1.35 --> 0.11 transition is 1235.8 ± 0.2 keV. Using Ex = 109.894 ± 0.005 keV for the energy of the first excited state, Ex for 19F* is then 1345.7 ± 0.2 keV (WA67F). At Eα = 12.7 MeV, a state at 4.648 MeV is populated which is then observed to γ-decay to the 9/2+ state at 2.78 MeV. The angular distribution of the cascade γ-rays and the lifetime of 19F*(4.65), set Jπ = 13/2+ for 19F*(4.65) (JA69N). For reaction (b) see 18O (NA79F). For reactions (c) and (d) see (CH72G; Eα = 60.2 MeV).
Elastic angular distributions have been reported in both reactions at E(Li) = 20 and 34 MeV: see (78AJ03).
For reaction (a) see (KN71). Angular distributions [reaction (b)] involving 19F*(0, 0.197, 1.55) have been studied at E(12C) = 40.6 MeV (KA80K). See also (78AJ03). Fusion cross section measurements are reported by (SP76G, KO77Z, KO79Y). See also (CO80T, MA81T) and (BI78, HO78H, VA78G, NA79, LO80; theor.).
Elastic angular distributions have been studied at E(16O) = 21.4 and 25.8 MeV and at E(19F) = 27, 30, 33 and 36 MeV (reaction (a)) [also to 19F*(1.46) at the two higher energies] and at 27, 30 and 33 MeV [reaction (b)]: see (78AJ03). See also (GA79C) and (OH80; theor.).
For fusion cross sections see (LE81C).
At Ed = 52 MeV 3He angular distributions are reported corresponding to some unresolved states in 19F and to 19F*(2.78, 5.62, 10.41) [the first two involve l = 4 and l = 1]: see (78AJ03).
At Ep = 45 MeV, 3He groups are observed to some T = 1/2 states in 19F and to 3/2+, T = 3/2 analog of 19O*(0.095): Ex = 7.660 ± 0.035 MeV (HA69H). At Ep = 40 MeV comparison of the ground-state angular distributions in this reaction and in the mirror (p, t) reaction [see reaction 18 in 19Ne] shows a suppression of the S = 1, T = 0 component of the (p, 3He) cross section: this is observed to occur for all TZ = 1/2 nuclei with A < 40 (NA76N).