论文标题
了解$^{22} $ na的宇宙丰度：$^{23} $ mg中的终身测量值
Understanding the cosmic abundance of $^{22}$Na: lifetime measurements in $^{23}$Mg
论文作者
论文摘要
Novae中爆炸性核合成的模拟预测了$^{22} $ na的产生，这是可观察到的关键天文学，以限制Nova模型。伽马射线太空望远镜尚未观察到它的伽马射线线1.275 MEV。 Presolar Grains中的$^{20} $ ne/$^{22} $ ne比率，这是识别Nova Grains的可能工具，也取决于$^{22} $ na产生的工具。目前，其经典Novae产量的不确定性源于$^{22} $ na（p，$γ$）$^{23} $ mg反应的速率。在Novae的峰值温度下，该反应以E $ _ {\ text {r}} $ = 0.204 MEV为主导，对应于$ e_x $ = 7.785 MEV激发态，$^{23} $ mg。到目前为止，共振强度的分量数量不同意。已经在Ganil进行了一个实验，以测量该关键状态的寿命和质子分支比，并用前者的飞秒分辨率进行了分辨率。已经研究了$^{23} $ mg中填充状态的反应，并使用高分辨率检测设置，即粒子vamos，蜘蛛和伽马跟踪Agata光谱仪，从而允许测量寿命和质子分支。我们在这里介绍了实验结果和壳模计算之间的比较，这使我们能够分配关键状态的自旋和奇偶校验。相当小的值为减少的$ M1 $矩阵元素，$ | M（M1）| \ Lessim 0.5 $ $ $ $μ_n$和PROTON SPECTROSCOPIC因子，$ C^{2} s _ {\ text {p Text {p}} $ <10 $ <10 $^{ - 2} $，似乎超出了壳牌模型的精度。通过重新评估$^{22} $ na（p，$γ$）$^{23} $ mg速率，$^{22} $ na可检测性限制及其从NOVAE的观察频率有望为未来的太空望远镜提供。
Simulations of explosive nucleosynthesis in novae predict the production of $^{22}$Na, a key astronomical observable to constrain nova models. Its gamma-ray line at 1.275 MeV has not yet been observed by the gamma-ray space telescopes. The $^{20}$Ne/$^{22}$Ne ratio in presolar grains, a possible tool to identify nova grains, also depends on $^{22}$Na produced. Uncertainties on its yield in classical novae currently originate from the rate of the $^{22}$Na(p, $γ$)$^{23}$Mg reaction. At peak novae temperatures, this reaction is dominated by a resonance at E$_{\text{R}}$=0.204 MeV, corresponding to the $E_x$=7.785 MeV excited state in $^{23}$Mg. The resonance strengths measured so far disagree by one order of magnitude. An experiment has been performed at GANIL to measure the lifetime and the proton branching ratio of this key state, with a femtosecond resolution for the former. The reactions populating states in $^{23}$Mg have been studied with a high resolution detection set-up, i.e. the particle VAMOS, SPIDER and gamma tracking AGATA spectrometers, allowing the measurements of lifetimes and proton branchings. We present here a comparison between experimental results and shell-model calculations, that allowed us to assign the spin and parity of the key state. Rather small values obtained for reduced $M1$ matrix elements, $|M(M1)|\lesssim 0.5$ $μ_N$, and proton spectroscopic factors, $C^{2}S_{\text{p}}$<10$^{-2}$, seem to be beyond the accuracy of the shell model. With the reevaluated $^{22}$Na(p, $γ$)$^{23}$Mg rate, the $^{22}$Na detectability limit and its observation frequency from novae are found promising for the future space telescopes.
