High-brightness beam diagnostics for the APS linac

The Advanced Photon Source (APS) injector includes an S-band linac with the capability to accelerate beams to 650 MeV. The linac has recently been upgraded with the installation of an RF thermionic gun in addition to the standard DC thermionic gun. The RF gun is predicted to have lower emittance (5 π mm mrad) and may be used to support the APS self-amplified spontaneous emission (SASE) experiments. The critical characterization of this gun´s beam has begun with a beam diagnostics station at the end of the linac that can address beam transverse size, emittance, and bunch length (peak current). This station uses both an optical transition radiation (OTR) screen at 45° to the beam direction and a Ce-doped YAG single crystal normal to the beam with a 45° mirror behind it. The visible light images are detected by a Vicon CCD camera and a Hamamatsu C5680 synchroscan streak camera. Spatial resolution of about 30 μm (σ) and temporal resolution of 1 ps (σ) have been demonstrated. Examples of RF gun beam characterization at 220 MeV are reported