Background] ${}^{19}$Ne is an important isotope in nuclear astrophysics due to its role in both the ${}^{18}$F($p$,$\alpha$)${}^{15}$O and ${}^{15}$O($\alpha$,$\gamma$)${}^{19}$Ne reactions in novae and Type I x-ray bursts, respectively. The energy levels of ${}^{19}$Ne near the $\alpha$ and proton thresholds ($S_{\alpha }$ = 3529 keV, $S_p$ = 6410 keV) correspond to resonances in both of these reactions. Previous measurements to study the structure of ${}^{19}$Ne have focused on both regions in an effort to constrain these reaction rates. [Purpose] Discrepancies in the energies, spins, and parities for levels in ${}^{19}$Ne from previous measurements contribute to the reaction-rate uncertainties. Gamma rays from the depopulation of excited states in ${}^{19}$Ne were measured to reduce the level-energy uncertainties and inconsistencies in previous spin-parity assignments. [Methods] The ${}^{19}$F(${}^3$He,$t$)${}^{19}$Ne reaction was used to elucidate the structure of ${}^{19}$Ne levels up to $E_x=6.9$ MeV. The reaction products were measured using Gammasphere ORRUBA: Dual Detectors for Experimental Structure Studies—a coupling of the Oak Ridge Rutgers University Barrel Array and Gammasphere at Argonne National Laboratory. Tritons produced in the reaction were measured in coincidence with $\gamma$ rays from the de-excitation of ${}^{19}$Ne energy levels. [Results] Previously unobserved transitions allowed for discrepancies in the resonance properties relevant to these two reactions to be resolved. In total, 41 transitions from 21 energy levels were measured in ${}^{19}$Ne, with 21 of those transitions being previously unobserved. Of particular importance, transitions from two 3/2${}^{+}$ states with energies of 6423(3) and 6441(3) keV, crucial for accurate estimations of the ${}^{18}$F($p$,$\alpha$)${}^{15}$O reaction rate, were found. [Conclusions] Energies and spin-parities of important energy levels near the proton and $\alpha$ thresholds were measured and some of the discrepancies in previous measurements were resolved. Measurement of the two near-threshold 3/2${}^{+}$ states reduced the calculated upper limit of the ${}^{18}$F($p$,$\alpha$)${}^{15}$O reaction rate by factors of 1.5-17 in the nova temperature range.

中文翻译：

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研究19Ne能级结构的爆炸性核合成

背景] ${}^{19}$Ne是原子核天体物理学中的重要同位素，因为它在原子能 ${}^{\mathrm{18岁}}$F（$p$，$\alpha$）${}^{15}$O和 ${}^{15}$O（$\alpha$，$\gamma$）${}^{19}$新星和I型X射线爆发中的Ne反应。的能级${}^{19}$Ne附近 $\alpha$ 和质子阈值（${\mathrm{小号}}_{\alpha }$ = 3529 keV， ${\mathrm{小号}}_p$= 6410 keV）对应于这两个反应的共振。先前的测量来研究结构${}^{19}$Ne集中在两个区域上，以限制这些反应速率。[目的]能量，自旋和奇偶性水平的差异${}^{19}$先前测量的Ne会增加反应速率的不确定性。伽马射线来自激发态的减少${}^{19}$对Ne进行测量以减少先前自旋奇偶校验分配中的能级不确定性和不一致性。[方法]${}^{19}$F（${}^3$他，$Ť$）${}^{19}$Ne反应用于阐明 ${}^{19}$Ne水平高达 ${Ë}_X=6.9$MeV。反应产物使用伽玛球ORRUBA：用于实验结构研究的双重检测器进行了测量-橡树岭罗格斯大学桶阵列和阿贡国家实验室的伽玛球的耦合。反应中产生的核与$\gamma$ 来自去激励的光线 ${}^{19}$Ne能级。[结果]以前未观察到的跃迁允许解决与这两个反应有关的共振性质的差异。总共测量了21种能级的41种转变${}^{19}$Ne，其中有21个转换之前从未观察到。从两个3/2过渡特别重要${}^{+}$ 能量为6423（3）和6441（3）keV的状态，对于精确估计 ${}^{\mathrm{18岁}}$F（$p$，$\alpha$）${}^{15}$发现了O反应速率。[结论]质子和质子附近重要能级的能量和自旋奇偶性$\alpha$测量了阈值，并解决了先前测量中的一些差异。测量两个近阈值3/2${}^{+}$ 州降低了计算的上限 ${}^{\mathrm{18岁}}$F（$p$，$\alpha$）${}^{15}$在新星温度范围内，O反应速率为1.5-17的倍数。