γ -ray spectroscopy of astrophysically important states in Ca39
γ -ray spectroscopy of astrophysically important states in Ca39
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Ca39 中天体物理重要状态的 γ 射线光谱
DOI：
10.1103/physrevc.101.015804
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发表时间：
2020
影响因子：
3.1
通讯作者：
Ayangeakaa, A. D.
中科院分区：
文献类型：
--
作者：
Hall, M. R.;Bardayan, D. W.;Baugher, T.;Lepailleur, A.;Pain, S. D.;Ratkiewicz, A.;Ahn, S.;Allen, J. M.;Anderson, J. T.;Ayangeakaa, A. D.
背景：新星爆炸合成的元素高达，计算和观测到的爆炸产生的Ar和Ca的丰度之间存在差异。已经证明，在新星核合成的终点，反应速率对这些同位素丰度有影响。三个最重要的共振的能量，对应于质子分离阈值以上的原子核中的激发态，是不确定的，其中一个在以前的实验中已经用相互冲突的值[VersuskeV]测量过。目的：减少共振能量的不确定性将允许更好地理解反应速率。为了改善这些不确定性，我们寻找了来自相应激发态布居减少的射线。方法：我们报道了一种通过观察以前未观察到的射线跃迁来测量这些共振能量的新方法。这些转变是通过用GAMASHERY ORRUBA实验结构研究双探测器(女神)研究反应观察到的。结果：总共发现了23个新的跃迁，其中包括与能量为6156.2(16)、6268.8(22)和6470.8(19)keV的天体物理感兴趣的三个态相对应的三射线跃迁。这与386(2)，498(2)和701(2)keV反应的共振能相对应。结论：最新的反应速率计算表明，在新星温度下，反应的上限有所降低。然而，低于之前测量的498keV共振的能量和其共振强度的不确定性增加了速率的上限，接近先前估计的0.4GK。
Background:Nova explosions synthesize elements up to, and discrepancies exist between calculated and observed abundances of Ar and Ca created in the explosion. Thereaction rate has been shown to be influential on these isotopic abundances at the endpoint of nova nucleosynthesis. The energies of the three most important resonances, corresponding toexcited states in thenucleus above the proton separation threshold, are uncertain and one has been measured with conflicting values [versuskeV] in previous experiments.Purpose:Reducing the uncertainties on the resonance energies would allow for a better understanding of the reaction rate. To improve these uncertainties, we searched forrays from the depopulation of the corresponding excited states in.Methods:We report a new measurement of these resonance energies via the observation of previously unobserved-ray transitions. These transitions were observed by studying thereaction with Gammasphere ORRUBA Dual Detectors for Experimental Structure Studies (GODDESS). The updated resonance energies were then used to calculate thereaction rate and assess its uncertainties.Results:In total, 23 new transitions were found, including three-ray transitions corresponding to the threestates of astrophysical interest at energies of 6156.2(16), 6268.8(22), and 6470.8(19) keV. These correspond to resonance energies in thereaction of 386(2), 498(2), and 701(2) keV.Conclusions:Updatedreaction rate calculations show a reduced upper limit at nova temperatures. However, the lower-than-previously-measured energy of the 498-keV resonance and uncertainty in its resonance strength increases the upper limit of the rate close to previous estimates at 0.4 GK.