发表机构
Louisiana State University; TRIUMF; Florida State University; University of Notre Dame; University of York; GSI Helmholtzzentrum für Schwerionenforschung GmbH; Monash University; Argonne National Laboratory（路易斯安那州立大学; 特里姆夫实验室; 佛罗里达州立大学; 圣母大学; 约克大学; 德国重离子研究中心; 蒙纳士大学; 阿贡国家实验室）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
首次直接测量$^{18}$F($\alpha,p$)$^{21}$Ne反应截面，结合先前数据与统计模型计算，显著降低反应速率不确定性，使AGB模型预测更可靠，并发现$^{19}$F产量增加45%。
AI 中文摘要
$^{18}$F($\alpha,p$)$^{21}$Ne反应可能影响渐近巨星支（AGB）星核合成以及吸积白矮星上的氦燃烧。该反应此前从未被直接测量过，而先前时间逆反应测量给出的约束导致反应速率存在很大不确定性。我们首次直接测量了$^{18}$F($\alpha,p$)$^{21}$Ne反应在$2 \leq E_{cm} \leq 4$ MeV能区内的截面。将这些结果与先前工作相结合，并与统计模型计算进行比较，反应速率的不确定性得到了显著改善。实验在TRIUMF-ISAC利用放射性$^{18}$F束流和带有扩展$^{4}$He气体靶的ANASEN装置，以逆运动学方式测量了截面。质子由硅微条探测器阵列探测，通过测量其径迹和能量，重建了质心系能量以及$^{21}$Ne中被布居的末态。我们发现总截面与统计模型计算符合良好，但$^{21}$Ne第二激发态的布居数高于理论预测。本次直接测量与先前的时间逆测量结果相结合，计算了0.1–3 GK温度范围内的新反应速率。$^{18}$F($\alpha,p$)$^{21}$Ne反应速率的不确定性已降低到足以使AGB模型进行可靠预测的水平。与先前速率相比，新的推荐速率导致$^{19}$F产量增加45%。
英文摘要
The $^{18}$F($α,p$)$^{21}$Ne reaction may impact Asymptotic Giant Branch nucleosynthesis and helium burning on accreting white dwarfs. This reaction has never been directly measured, and constraints from a previous time-inverse measurement leave large uncertainties in the reaction rate. We measured $^{18}$F($α,p$)$^{21}$Ne cross sections directly for the first time covering from $2 \leq E_{cm} \leq 4$ MeV. Combining these results with previous work and comparisons to statistical model calculations results in a substantial improvement in uncertainties in the reaction rate. Cross sections were measured in inverse kinematics at TRIUMF-ISAC using a radioactive $^{18}$F beam and ANASEN with an extended $^{4}$He gas target. Protons were detected in arrays of silicon-strip detectors with the measured trajectories and energies allowing reconstruction of the center-of-mass energy and final state in $^{21}$Ne populated. We found the total cross section is in good agreement with statistical calculations, though population of the second excited state in $^{21}$Ne is greater than predicted. This direct measurement is combined with the previous time-inverse measurement and a new reaction rate is calculated for 0.1--3 GK. The uncertainties in the $^{18}$F($α,p$)$^{21}$Ne reaction rate have been reduced to a sufficient level to allow robust predictions from AGB models. The new recommended rate leads to a 45\% increase in $^{19}$F production compared to the previous rate.
