The ${}^{17}\mathrm{F}$($p,\gamma$)${}^{18}\mathrm{Ne}$ resonant cross section

We directly measure the ${}^{17}\mathrm{F}$($p$,$\gamma$)${}^{18}\mathrm{Ne}$ resonant reaction using a mixed beam of ${}^{17}\mathrm{F}$ and ${}^{17}\mathrm{O}$ at the Holifield Radioactive Ion Beam Facility at Oak Ridge National Laboratory (ORNL). The astrophysically important $3^{+}$ resonance at $~600$ keV above the proton threshold in ${}^{18}\mathrm{Ne}$ is found to have a partial width ${\Gamma }_{\gamma }=56\pm 24(\mathrm{stat})\pm 30(\mathrm{sys})$ meV, in reasonable agreement with the theoretically predicted width. A $2\sigma$ upper limit on the direct capture of $S(E)⩽65$ keV b is determined at an energy of 800 keV. Experimental techniques and astrophysical implications are discussed.

Figure 1

Astrophysical $S$ factor for the ${}^{17}\mathrm{F}$ proton capture; the dashed line is the expected curve for the state predicted by Wiescher et al. [9] and the solid curve is calculated by García et al. [10] for the same predicted state. The figure is originally from Ref. [10].

Figure 2

Representative spectrum from the “plunger” beam-current monitor. The (black) dark curve is the characteristic signal from the scintillator paddles in coincidence, showing a spike and decay each time the plate is retracted from the beam axis. The (blue) light curve displays the live time of the data acquisition system.

Figure 3

Schematic of the location of each of the beam monitoring detectors (see text).

Figure 4

Energy loss versus total energy from the ionization chamber for the 557 keV resonance in ${}^{17}\mathrm{O}$($p$,$\gamma$)${}^{18}\mathrm{F}$.

Figure 5

Ionization chamber spectrum for the ${}^{17}\mathrm{O}+{}^{20}\mathrm{Ne}$ scattering measurement with Ne recoils indicated; performed to verify the location of ${}^{18}\mathrm{Ne}$ recoils during the ${}^{17}\mathrm{F}$($p$,$\gamma$)${}^{18}\mathrm{Ne}$ experiment.

Figure 6

Energy loss versus total energy from the ionization chamber for the 599.8 keV resonance; ${}^{18}\mathrm{Ne}$ recoils are indicated by the black circle.

Figure 7

Experimentally determined charge-state distribution for the ${}^{18}\mathrm{Ne}$ recoils from the 599.8 keV resonance. (Blue) curve is a Gaussian fit to the data.

Figure 8

Reaction rates over the temperature range $0.1⩽T_9⩽0.6$ for this work. Both the $3^{+}$ contribution and total are shown. The (blue) diagonal hash marks display the one-$\sigma$ uncertainties in the total rate from this work and the (red) dotted band indicates the one-$\sigma$ uncertainties on the resonant rate alone [2]. The two-$\sigma$ upper limit on the total reaction rate is also shown.

Figure 9

Abundance versus time for the ${}^{18}\mathrm{F}$ (black/grey) and ${}^{17}\mathrm{O}$ (blue/turquoise) in a 1.35 solar mass ONeMg nova. In each case, the outer lines designate the upper and lower limits from the previous rate, and the inner lines designate the upper and lower limits from this work.

Figure 10

Abundance versus time for the ${}^{17}\mathrm{F}$ (top), ${}^{18}\mathrm{F}$ (middle), and ${}^{17}\mathrm{O}$ (bottom) within the “ignition zone” of an x-ray burst. In each case the outer lines designate the upper and lower limits from the previous rate and the inner lines designate the upper and lower limits from this work.