Abstract: A radiation source assembly and a connector press used in producing such assemblies. In the radiation source assembly, each of the cap connector and the female connector is provided with internal round threads on its pigtail fitting hole, thus engaging with the large-diameter coil of the pigtail at the internal round threads through a thread engagement prior to a compression process of the press. The assembly also allows a person to know whether both ends of the pigtail fully reach desired points within the two connectors, thus securing a precise compressing target portion during a compression process of the press. The inserted lengths of the pigtail relative to the two connectors are maximize accomplishing a desired linearity of the assembly. In the assembly, a target biasing spring is provided on the capsule lid and allows the disc targets within the source capsule to effectively maintain a desired condition as point sources regardless of the number of targets.