Improved astrophysical rate for the 18O(p,a)15N reaction by underground measurements
Improved astrophysical rate for the 18O(p,a)15N reaction by underground measurements
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通过地下测量提高 18O(p,a)15N 反应的天体物理速率
DOI：
10.1016/j.physletb.2019.01.017
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发表时间：
2019
影响因子：
4.4
通讯作者：
Bruno C
中科院分区：
文献类型：
--
作者：
Bruno C
18o (p, α) 15n反应影响15n、18o和19f同位素的合成，这些同位素的丰度可以用来探测发生在渐近巨支（AGB）恒星内部深处的核合成和混合过程。我们在地下核天体物理实验室（LUNA）对18o (p, α) 15n反应的横截面进行了低背景直接测量，从质能中心E cm= 340 keV到E cm= 55 keV，这是迄今为止测量到的最低能量，对应的横截面小于1皮巴/sr。质能中心E r= 90 keV处的键共振强度比先前报道的高10倍。多通道r矩阵分析我们和其他文献中可用的数据进行。在很宽的温度范围内，T= 0.01-1.00 GK，我们新的天体物理速率比最近的评估更准确和精确。现在可以对控制AGB恒星核合成的物理过程施加更强的限制，这对这些恒星和星尘颗粒中18o的丰度，特别是富氧II族颗粒的产生部位产生了有趣的影响。
Abstract The 18 O (p, α) 15 N reaction affects the synthesis of 15 N, 18 O and 19 F isotopes, whose abundances can be used to probe the nucleosynthesis and mixing processes occurring deep inside asymptotic giant branch (AGB) stars. We performed a low-background direct measurement of the 18 O (p, α) 15 N reaction cross-section at the Laboratory for Underground Nuclear Astrophysics (LUNA) from center of mass energy E cm= 340 keV down to E cm= 55 keV, the lowest energy measured to date corresponding to a cross-section of less than 1 picobarn/sr. The strength of a key resonance at center of mass energy E r= 90 keV was found to be a factor of 10 higher than previously reported. A multi-channel R-matrix analysis of our and other data available in the literature was performed. Over a wide temperature range, T= 0.01–1.00 GK, our new astrophysical rate is both more accurate and precise than recent evaluations. Stronger constraints can now be placed on the physical processes controlling nucleosynthesis in AGB stars with interesting consequences on the abundance of 18 O in these stars and in stardust grains, specifically on the production sites of oxygen-rich Group II grains.