论文标题
散布中子源处的四维发射率测量
Four-dimensional emittance measurement at the Spallation Neutron Source
论文作者
论文摘要
具有椭圆形横向轮廓，均匀电荷密度和小横向四维（4D）发射率的海岸强子梁可以在几种情况下提高加速器性能。一种相位空间绘画方法正在在散布中子源（SNS）蓄能环中测试产生这种分布的方法。这些努力的关键组成部分是在积累过程中测量光束的4D发射率。可以通过两种方式从测量的束轮廓重建4D发射：在多访问方法中，重建和测量位置之间的光学分数变化；在固定选择方法中，使用多个测量位置而不修改光学元件。固定选择方法更快，但可能导致重建的4D发射率较大的不确定性。在本文中，我们使用SNS目标附近的四个可用电线扫描仪实现了多播方法的变体。我们还修改了电线扫描仪区域，以减少固定镜方法的不确定性。然后，我们通过重建SNS环积累过程中的4D发射率演变来证明固定访问方法的有用性。
A coasting hadron beam with an elliptical transverse profile, uniform charge density, and small transverse four-dimensional (4D) emittance could improve accelerator performance in several contexts. A phase space painting method to generate such a distribution is being tested in the Spallation Neutron Source (SNS) accumulator ring. A critical component of these efforts is to measure the 4D emittance of the beam during accumulation. The 4D emittance can be reconstructed from measured beam profiles in two ways: in the multi-optics method, the optics between a reconstruction and measurement location are varied; in the fixed-optics method, multiple measurement locations are used without modifying the optics. The fixed-optics method is faster but can lead to large uncertainty in the reconstructed 4D emittance. In this paper, we implement a variant of the multi-optics method using the four available wire-scanners near the SNS target. We also modify the wire-scanner region to reduce the uncertainty of the fixed-optics method. We then demonstrate the usefulness of the fixed-optics method by reconstructing the 4D emittance evolution during accumulation in the SNS ring.
