标题： 关键$^{19}$状态影响$γ$射线从$^{18}$F 的新星发射 显示英文标题

标题： Key $^{19}$Ne states identified affecting $γ$-ray emission from $^{18}$F in novae

摘要： 核衰变$\gamma$射线的检测为新星核合成提供了一种灵敏的温度计。 最强烈的$\gamma$-射线通量被认为是来自$^{18}$F的$\beta^+$衰变的湮灭辐射，该物质在衰变前通过$^{18}$F($p$,$\alpha$)$^{15}$O反应被破坏。 Estimates of $^{18}$F production had been uncertain, however, because key near-threshold levels in the compound nucleus, $^{19}$Ne, had yet to be identified. 此信件报告了首次对$^{19}$F($^{3}$He,$t\gamma$)$^{19}$Ne 反应的测量，在该反应中，通过三重子-$\gamma$-$\gamma$共振确定了两个长期寻求的 3/2$^+$能级的位置。 它们共振能量的精确确定在新星温度下将速率上限降低了$1.5-17$倍，并将新星探测概率的平均不确定性降低了2.1倍。 显示英文摘要

摘要： Detection of nuclear-decay $\gamma$ rays provides a sensitive thermometer of nova nucleosynthesis. The most intense $\gamma$-ray flux is thought to be annihilation radiation from the $\beta^+$ decay of $^{18}$F, which is destroyed prior to decay by the $^{18}$F($p$,$\alpha$)$^{15}$O reaction. Estimates of $^{18}$F production had been uncertain, however, because key near-threshold levels in the compound nucleus, $^{19}$Ne, had yet to be identified. This Letter reports the first measurement of the $^{19}$F($^{3}$He,$t\gamma$)$^{19}$Ne reaction, in which the placement of two long-sought 3/2$^+$ levels is suggested via triton-$\gamma$-$\gamma$ coincidences. The precise determination of their resonance energies reduces the upper limit of the rate by a factor of $1.5-17$ at nova temperatures and reduces the average uncertainty on the nova detection probability by a factor of 2.1.