Measurements of Transverse Emittance for RF Photocathode Gun at the PAL

A BNL GUN-IV type RF photo-cathode gun is under fabrication for use in the FIR (Far Infrared) facility being built at the Pohang Accelerator Laboratory (PAL). Performance test of the gun will include the measurement of transverse emittance profile along the longitudinal direction. Precise measurement of the emittance profile will provide powerful tool for the commissioning of the 4GLS (4th generation light source) injectors based on the emittance compensation principle. We are going to achieve this with the use of Pin-hole plate based Emittance-Meter that can be moved along the longitudinal direction. In this article, we present design considerations for the Emittance-Meter which is capable of measuring emittance as low as 1 mm mrad.