(See Energy Level Diagrams for 19F)
Special states: (1978WI1B, 1982RA1N, 1983BI1C, 1983BR29, 1983CS01, 1983PO02, 1984AD1E, 1984HO1H, 1984ME02, 1984MI1H, 1984RA13, 1984WI17, 1985AD1A, 1985BR15, 1985DI16, 1985MI10, 1985MO20, 1986AN07, 1986CA27, 1986HA1Q, 1986KA1D, 1986WI1P, 1987DE05).
Complex reactions involving 19F: (1982HO10, 1983DE26, 1983JA05, 1983LE1F, 1983SO08, 1983WI1A, 1984BE22, 1984FI17, 1984GR08, 1984HI1A, 1984HO23, 1984NA12, 1984RA10, 1984SI15, 1985AG1A, 1985BE40, 1985GR1J, 1985HO05, 1985MC03, 1985MO08, 1985OS05, 1985PO11, 1985WA22, 1986AI1A, 1986FE03, 1986GR1A, 1986GR1B, 1986HA1B, 1986PL02, 1986PO06, 1986SA30, 1986SC28, 1986SC29, 1986SH2B, 1986SH1F, 1986SO10, 1986VA23, 1986WE1C, 1987KO15, 1987PA01, 1987RI03).
μg.s. = +2.628866 (8) nm (1978LEZA).
μ0.197 = +3.607 (8) nm (1978LEZA).
Q0.197 = -0.12 ± 0.02 b (1978LEZA).
Vector analyzing power measurements for the elastic scattering have been reported at E(pol. 7Li) = 21.1 MeV (1984MO06). Fusion cross sections have been measured by (1982DE30). For other channels in the interaction of 12C + 7Li see (1978AJ03, 1983AJ01). See also (1986KA1C, 1986MO1E) and (1985SA13, 1986YO1A; theor.).
Uncorrelated structures have been observed in the excitation functions for reactions (a) and (b). Fusion cross sections have also been measured: see (1983AJ01). See also (1981GL02) for reaction (a), 13C and 15N in (1986AJ01) and 16O in (1986AJ04).
Resonances in yield of γ-rays are observed below Eα = 10.4 MeV: the parameters for these are displayed in Table 19.10 (in PDF or PS). Branching ratios are shown in Table 19.7 (in PDF or PS) and τm measurements in Table 19.8 (in PDF or PS). The Jπ values shown in Table 19.10 (in PDF or PS) are based on correlation and angular distribution measurements and on branching ratio determinations. See also (1985DI16).
The Ex of states involved in cascade decays are 3999.6 ± 1.2, 4031.9 ± 0.4, 4377 ± 1 and 4548 ± 2 keV. 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-]) and possibly 19F*(8.29)[13/2-] [Jπ in brackets]. See, however, reaction 9. See (1972AJ02) 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. For references see (1983AJ01).
At E(6Li) = 22 MeV angular distributions are reported to 19F*(0.11, 1.35[u], 1.46, 4.0[u], 8.29[u], 8.96[u]). Comparisons are made with the results from the 16O(6Li, d)20Ne reaction, in an attempt to determine whether 19F*(8.95) is the 11/2- member of the Kπ = 1/2- band, of which 19F*(8.29) is the 13/2- member (1984MO08, 1985MO20) [but see (1985DI16)]. Configuration mixing in the 11/2- states [19F*(7.17, 8.95, 9.87)] and in the 7/2- states [19F*(4.00, 5.42)] to which they decay appears to be involved (1987FO03).
At E(13C) = 105 MeV groups are reported to states which are generally unresolved; Jπ assignments are suggested: see (1983AJ01).
For reaction (a) see (1978AJ03). 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 (1978AJ03). 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 (1982AO06, 1983AO03; theor.).
Angular distributions have been measured at Eα = 20.1 to 40 MeV: see (1978AJ03, 1983AJ01). States observed in this reaction are displayed in Table 19.2 (in PDF or PS) of (1978AJ03). See also (1986LE1Q; theor.).
This reaction (and its mirror reaction 16O(6Li, t)19Ne [see 19Ne]) have been studied at E(6Li) = 24 and 46 MeV: see (1978AJ03, 1983AJ01). Members of the Kπ = 1/2+ and 1/2- rotational bands have been identified: see Table 19.13 (in PDF or PS). Other groups, mainly to unresolved states, have also been observed.
Many states have been populated in this reaction: see Table 19.14 (in PDF or PS) in (1978AJ03) and (1984MO28; E(7Li) = 20 MeV). Angular distributions in the latter work have been analyzed via Hauser-Feshbach compund nucleus calculations and FRDWBA, The Kπ = 1/2+ and 1/2- states [see Table 19.13 (in PDF or PS)] are discussed (1984MO28).
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 are predominantly (sd)3: see (1983AJ01).
This reaction has recently been studied for Ep = 80 to 2200 keV by (1980WI17). 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 distribution data lead to Jπ assignments: see Tables 19.7 (in PDF or PS), 19.14 (in PDF or PS) and 19.15 (in PDF or PS) for a display of the results (1980WI17).
In addition absolute cross sections measured for direct capture lead to C2S values for a number of states of 19F. Reduced widths and Jπ determinations lead (1980WI17) 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+ states of Kπ = 3/2+ rotational band; 19F*(7.70 or 7.26, 6.09, 9.82, 6.93, 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 (1980WI17). See also Table 19.6 (in PDF or PS).
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 by (1980WI17). See also (1982KR05), (1982RO1A, 1982WI1B; astrophysics) and (1982MA1Q, 1983AM1D; applications).
Scattering studies have been carried out for Ep = 0.6 to 16.3 MeV and for Epol. p = 6.1 to 16.6 MeV: see (1978AJ03, 1983AJ01). Pronounced resonant structure is evident up to 14 MeV. Observed resonances are shown in Table 19.17 (in PDF or PS). For polarization measurements see (1982GL08; Epol. p = 800 MeV). See also (1982NA13, 1984PH02, 1986DE1G; theor.).
Yield measurements have been studied for Ep = 72 keV to 14 MeV: see (1972AJ02, 1983AJ01): observed resonances are displayed in Table 19.17 (in PDF or PS). See also (1982RO1A, 1982WI1B, 1984HA1R, 1984HA1Z, 1986BA89, 1987RO25; astrophys.) and (1982MA1Q, 1986CO2B; applied).
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 (1978AJ03) and Table 19.18 (in PDF or PS) here.
Angular distributions of the deuterons corresponding to many states of 19F have been analyzed by DWBA: the results are shown in Table 19.18 (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: see (1978AJ03). A search for a state at Ex = 7.90 MeV [just below the 18O + p threshold, and of astrophysical interest] has been unsuccessful: θ2p < 5 × 10-5 (1986CH29). See also (1983MU13, 1984BL21; theor.).
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 19.19 (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). Gamma-ray branching ratios are displayed in Table 19.7 (in PDF or PS). See also (1983AJ01, 1985BR29).
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: see (1978AJ03). See also (1982COZV)), (1972AJ02), (1982VI07; applications) and (1983KA28; theor.).
(1984KE04) have measured absolute differential cross sections for the p0 and p1 channels at 7 angles for Eγ = 13.4 to 25.8 MeV. Angle integrated cross sections for (γ, p0) show pronounced structures at Eγ = 15.45, 16.70, 17.35 and 18.55 MeV as well as a broad bump at ≈ 20.5 MeV. Additional minor structures may exist at Eγ = 13.65, 14.35, 15.85, 17.90, 19.5, 21.3, 22.2 and 23.5 MeV. In the (γ, p1) reaction broad bumps appear at ≈ (17.0) and 21.5 MeV. The E2 cross section [from (γ, p0) angular distribution coefficients] is estimated to be ≈ 0.37 of the E2 EWSR (1984KE04). The (γ, ptot) cross section to 26 MeV has been derived by (1985KE03). See also (1978AJ03).
In reaction (b) the (γ, t0) reaction has been studied for Eγ = 18 to 23 MeV: two peaks are observed at Eγ = 18.8 and 20.1 MeV. It is suggested that Jπ = 1/2- or 3/2-, T = 1/2. The (γ, t0) process contributes ≈ 1% to the total GDR: see (1978AJ03).
The energy of the first excited state is 109.894 ± 0.005 keV; its width is (5.1 ± 0.7) × 10-7 eV. 19F*(1.46, 3.91, 7.66) are also excited. The scattering cross section is relatively small and structureless for Eγ = 14 to 30 MeV: see (1978AJ03).
With Ee = 78 to 340 MeV, and with an energy resolution of 25 - 50 keV, most states of 19F with Ex < 7.7 MeV have been observed and the longitudinal and transverse form factors have been derived and compared with shell-model calculations. The spectrum of positive-parity longitudinal excitations is dominated at higher momentum transfer by the 1/2+ → 9/2+ members of the ground state Kπ = 1/2+ band. The C2 strength is concentrated at Ex < 1.5 MeV with a small secondary concentration for 5.5 < Ex < 6.5 MeV. The C4 strength is spread from 3 to 6 MeV, dominantly in 19F*(2.78) [Jπ = 9/2+]. The spectra of longitudinal excitations of negative parity states are dominated by 19F*(1.35) [Jπ = 5/2-] and 19F*(5.5) [5/2- + 7/2-]. In the transverse mode 19F*(0.11, 6.79) [Jπ = 1/2-, 3/2-, respectively] are prominent. Agreement with theory is good for 5/2- and 7/2- but poorer for 1/2- and 3/2- states. The parity of 19F*(5.34) is uncertain while that of 19F*(6.55) is probably positive. States are reported at 7.587 and 7.753 MeV with Jπ = (5/2-) and (7/2-), respectively (1985BR15). The form factors for 19F*(0, 0.11, 2.78) have also been studied by (1986DO10) for q = 0.4 - 2.8 fm-1. For electromagnetic transition rates see Table 19.20 (in PDF or PS). For the earlier work see (1978AJ03, 1983AJ01). See also (1985TU1B, 1987DE43) and (1983BR27, 1986BO29, 1986BR1X; theor.).
Angular distributions of neutron groups have been reported at En = 2.6, 14.1 and 14.2 MeV: see (1972AJ02).
Table 19.21 (in PDF or PS) in (1978AJ03) displays energy levels of 19F derived from this reaction. Angular distributions of various proton groups have been measured from Ep = 4.3 to 35.2 MeV [see (1978AJ03, 1983AJ01)] and at Ep = 2.76 and 2.97 MeV (1986OU01). The ground-state rotational band is characterized by β2 = 0.44 ± 0.04, β4 = 0.14 ± 0.04. The g of 19F*(0.197) is 1.442 ± 0.003 (1969JBL18), 1.438 ± 0.005 (1984AS03). The mixing ratio for the 1.46 → 0.11 transition (3/2- → 1/2-; K = 1/2- band) δ(E2/M1) = 0.248 ± 0.020. The E2 strength is 18.7 ± 1.9 W.u. The 1.46 → 0 transition is pure E1 (δ = 0.01 ± 0.03). For references see (1983AJ01). See also 20Ne, (1985OU01, 1986HA1T) and (1983IK1B).
Elastic angular distributions have been studied for Et = 2 and 7.2 MeV: see (1972AJ02).
The energy of the γ-ray from the 1.35 → 0.11 transition is 1235.8 ± 0.2 keV; Ex is then 1345.7 ± 0.2 keV. |g| = 0.269 ± 0.043 (1983BI03). See also Table 19.7 (in PDF or PS). For τm see Table 19.8 (in PDF or PS). 19F*(4.65) decays to the 9/2+ state 19F*(2.78): the angular distribution of the cascade γ-rays and the τm of 19F*(4.65) set Jπ = 13/2+. See also (1980ZO04, 1984CS01, 1984SA28, 1986NO1F) and (1983AJ01).
Angular distributions (reaction (a)) have been studied at E(12C) = 40.6 MeV [see (1983AJ01)] and at 30.0 to 60.1 MeV [as well as at E(19F) = 63.8 MeV] (1984TA08, 1986TAZO; to 19F*(0, 0.197, 1.55, 2.78)) and at E(19F) = 46.5 to 57.1 MeV (1984MA32; to 19F*(0, 0.197)) [see it and (1986VO12) for yield measurements].
Angular correlations involving the α-decay to 15Ng.s. of twenty 19F states have been measured at E(19F) = 78.5, 82 and 144 MeV and analyzed with DWBA and strong absorption model calculations. Two new states with Jπ = 5/2- or 7/2- are reported at 7.740 and 8.277 MeV [estimated ± 0.04 MeV]. It is suggested that 19F*(7.26, 9.287) are 3/2+ and 7/2+, 9/2+, respectively (1985SM04). See also (1986GA13, 1986IKZZ, 1986MA1Z), (1983AJ01, 1983BI13, 1984FR1A, 1984HA53, 1985HU04) and (1982GI1C, 1982LO13, 1983CI08, 1986HA13, 1986HE1A, 1987CO01; theor.).
Elastic scattering angular distributions have been studied at E(14N) = 19.5 MeV and at E(15N) = 23, 26 and 29 MeV: see (1983AJ01).
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 E(16O) = 60 and 80 MeV (1986FUZV; also to 19F*(0.20, 1.55, 2.78)), and at 27, 30 and 33 MeV [reaction (b)]: see (1978AJ03). See also (1986FU1C, 1986GA13), (1983DU13, 1986BA69) and (1982OH05; theor.).