Final answer:
The specific instrument used to detect if a 3rd rail has been re-energized is not detailed in the references provided, but it would likely be similar to a non-contact voltage tester or a specialized railroad voltmeter. Radiation detection instruments like Geiger counters are not used for this purpose. A GFCI is mentioned for electrical safety but is not the tool for detecting 3rd rail energization.
Step-by-step explanation:
The instrument used to detect whether a 3rd rail has been re-energized in an emergency or work area is not explicitly mentioned among the instruments described in the reference information provided. However, considering the context of electrical safety and power detection, a device similar to a non-contact voltage tester or a railroad voltmeter designed for the 3rd rail system might be utilized for this purpose. These are specialized tools used by electrical professionals to safely determine the presence of electrical current without direct contact. Instruments like Geiger counters, scintillation counters, and dosimeters are used to measure radiation and are not relevant to detecting electrical energization.
For ensuring electrical safety, tools like a ground fault circuit interrupter (GFCI) are crucial as they can prevent shock by detecting unintended current paths. While the reference information provides details on devices that measure radiation or detect explosives and weapons, the specific tool for detecting energization of the 3rd rail would be a device capable of identifying live electrical circuits.
Professionals working in the vicinity of third rails, which are used to provide electric power to trains and subways, must take precautions to ensure that the rail is de-energized before commencing work. The appropriate detection tool is crucial for this and typically has a digital readout to indicate the presence of voltage. Further training and equipment specifics would be required to properly identify and use such a device in a railway maintenance context.