基于超导加速器的脉冲慢正电子束时间结构计算
Calculation of the temporal structure for a pulsed slow positron beam based on superconducting accelerator
- Henan Academy of Sciences（河南省科学院）
- Institute of High Energy Physics, Chinese Academy of Sciences（中国科学院高能物理研究所）
机构由 AI 辅助整理，请以论文原文为准。
AI总结：
本文建立Geant4蒙特卡罗模拟与正电子扩散理论耦合的计算模型，评估超导加速器产生的脉冲慢正电子束在慢化过程中的时间展宽，结果显示经钨箔慢化后初始展宽约320皮秒，可直接用于正电子湮没寿命测量。
AI中文摘要：
超导加速器（SCA）的发展为产生具有高时间分辨率和高强度的脉冲慢正电子束提供了一种新方法。SCA能够产生重复频率在兆赫兹量级、脉冲宽度小于100皮秒的电子束。基于SCA的脉冲正电子束在一定程度上可以保留初级电子束的优良时间结构。然而，正电子在慢化体中的热化、扩散和表面再发射将不可避免地导致正电子脉冲的时间展宽。本文建立了一个将Geant4蒙特卡罗模拟与正电子扩散理论相结合的计算模型，以评估正电子慢化过程对时间展宽的影响。经过钨箔慢化后，脉冲慢正电子束的初始时间展宽约为320皮秒。结合脉冲束在输运过程中的时间展宽计算，预计由SCA产生的脉冲慢正电子束可直接应用于正电子湮没寿命的测量。
英文摘要：
The development of superconducting accelerator (SCA) provides a novel approach to generating pulsed slow positron beams with high time resolution and high intensity. SCAs can produce electron beams with repetition frequencies on the order of MHz and pulse widths of less than 100 ps. A pulsed positron beam based on SCA can, to a certain extent, preserve the excellent temporal structure of the primary electron beam. However, thermalization, diffusion, and surface re-emission of positrons in the moderator will inevitably lead to time broadening of positron pulses. In this paper, a calculation model coupling Geant4 Monte Carlo simulations with positron diffusion theory is established to evaluate the effect of the positron moderation process on time broadening. After being moderated by a tungsten foil, the initial time broadening of the pulsed slow positron beam is approximately 320 ps. By combining the time broadening calculation of pulsed beam during its transport, it is expected that the pulsed slow positron beam generated by the SCA, can be directly applied to the measurement of positron annihilation lifetime.
