ARC Centre for Antimatter-Matter Studies, Research School of Physics and Engineering, Australian National University, Canberra 0200 Australia.
Phys Rev Lett. 2010 Aug 13;105(7):073201. doi: 10.1103/PhysRevLett.105.073201.
Channel coupling is a phenomenon that has been investigated for many scattering processes, and is responsible for the formation of cusps or steps in the cross sections for open scattering channels at, or near, the onset of a new scattering channel. It has long been speculated that the opening of the positronium formation channel may lead to the formation of such cusp features in the elastic positron scattering cross section. In this work, elastic scattering of positrons has been measured in the region of the positronium formation threshold for the noble gases He-Xe. Cusplike behavior is observed and, while the features which are observed appear broad, they represent a magnitude of between 4 and 15% of the total elastic cross section. No evidence is found of any other features in this region, at least within the uncertainty of the present data, discounting the possibility of scattering resonances.
通道耦合是一种在许多散射过程中都有研究的现象，它导致了在新散射通道开始或接近开始时，开放散射通道的截面中出现尖峰或阶跃。长期以来，人们一直推测正电子素形成通道的开启可能导致弹性正电子散射截面中出现这种尖峰特征。在这项工作中，测量了在惰性气体氦-氙的正电子素形成阈区的正电子弹性散射。观察到了类峰特征，尽管观察到的特征看起来很宽，但它们代表了总弹性截面的 4%至 15%之间的量级。在该区域内没有发现任何其他特征，至少在当前数据的不确定度范围内，排除了散射共振的可能性。
