Detector grade diamond films have been prepared by DC Arc Plasma Jet chemical vapour deposition from CH4-H2 mixtures.Diamond detectors of pulsed radiation based on the films have been developed and preliminarily studied.The responses of the detector to 1.25MeV γ ray and pulsed ultraviolet laser with picosecond width show that this detector has a very fast time-response and about 70% charge collection efficiency.Its further applications will be found in sub-nanosecond pulse measurements.