Positron cooling by vibrational and rotational excitation of molecular gases
Positron cooling by vibrational and rotational excitation of molecular gases
复制标题
通过分子气体的振动和旋转激发进行正电子冷却
DOI：
10.1088/0953-4075/47/22/225209
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发表时间：
2014
期刊：
影响因子：
--
通讯作者：
C. Surko
中科院分区：
文献类型：
--
作者：
M. R. Natisin;J. Danielson;C. Surko
测量了正电子气体在高温（≥ 1200 ℃）下被限制在电磁阱中时的温度随时间的变化K），通过与分子气体CF 4？>，N 2？>或300 K时的CO。一个简单的模型描述正电子热化耦合振动和旋转模式，与玻恩近似计算的冷却速率预测。与测得的正电子冷却率曲线的比较允许估计相关截面的大小。结果进行比较与实验的情况下，振动激发，直接测量存在，他们提供的旋转激励截面的直接测量是目前不可能的估计。正电子冷却速率进行了比较，这些气体在300 K，并估计其有效性的冷却正电子到低温温度进行了讨论。
Measurements of positron temperature as a function of time are presented when a positron gas, confined in an electromagnetic trap at an elevated temperature ( ≥ 1200 ?> K), is cooled by interactions with the molecular gases CF 4 ?> , N 2 ?> or CO at 300 K. A simple model describing positron thermalization by coupling to vibrational and rotational modes is presented, with cooling-rate predictions calculated in the Born approximation. Comparisons to the measured positron cooling-rate curves permit estimates of the magnitudes of the relevant cross sections. The results are compared with experiment for the case of vibrational excitation, where direct measurements exist; and they provide estimates of the rotational excitation cross sections where direct measurements are not currently possible. Positron cooling rates are compared for these gases at 300 K, and estimates of their effectiveness in cooling positrons to cryogenic temperatures are discussed.