In a process for preparing polyethylene in tube reactors with or without autoclaves, where a free-radical initiator is introduced with or without cold ethylene into a flowing ethylene- and comonomer-containing medium, rotation is generated between two streams to be mixed at an angle or by provision of a swirl element in the flow cross section. At least one torque sensor is used to detect the occurrence of vibrations in the drivetrain and the torque sensor is used to determine vibration amplitude. The sequencing mechanism includes a sequence latch pivotally attached to the intermediate slide segment and configured to operate in both an upright orientation and an inverted orientation of the slide assembly. The plate is cooled to a temperature less than that of the reticle or sensor. The wideband biconical antenna has its feed disposed within a central conduit of the biconical antenna.