The primary test of measuring system for the actual emittance of relativistic electron beams

Recently, a novel system has been established in Tsinghua University, P.R. China. The system is able to measure the actual phase diagram of a relativistic electron beam (4–10 MeV). The system is mainly composed of a magnetic scanning system, a slit, a fluorescent screen and a CCD camera. After the assembling and testing of the system, as well as the composing of software of the image process, the actual emittance of the 4 MeV electron beam, which is from the standing wave linac in Accelerator Lab, is measured by this system and RMS. Emittance is also achieved. Lastly, the measurement error is analyzed and the overall performance is presented: the system error is 10%–20%, the scope of measurement is 0.4–350 mm mrad. Experiments show that the magnet scanning method is applicable and the system is preliminary practicable.