Beam halo observation image by a corona-graph

We have developed a corona-graph for the observation of the beam halo surrounding a beam. An opaque disk is set in the beam image plane to block the glare of the beam image. We succeeded in obtaining a signal to background ratio of 6.10-7. As a test, we tried to observe the beam halo at the Photon Factory storage ring. We succeeded in observing the tail of the beam, which has an intensity range of 10-4 to 10-6 of the peak intensity. This technique is applicable not only to observing the beam halo, but also has many possibilities such as the observation of an injected beam under the presence of an intense stored beam