Polaron

A polaron was a type of subatomic particle. Polaron radiation was fatal to humanoids, and also has a destabilizing effect on Changeling physiology. 

In 2269, the USS T'Saura attempted to use a polaron burst to disrupt a Gorn minefield blockade around the Delta Triangle. 

In 2373, Starfleet Science tried to create modified polaron emitters which could expose suspected Changelings, without doing harm to other species. 

Defensive usage
Numerous species used polaron-based weaponry and defensive systems, including:
 * The Borg
 * The Dominion
 * The Hierarchy
 * The Nyrians
 * The Swarm
 * The Varro

Other uses
Polarons can be used to locate space vessels in situations were normal sensors are inadequate. 

They can also be utilized to interfere with such energy-emitting systems as shields, tractor beams, and magnetic confinement fields. Similarly, polarons can be used to enhance such systems.