Radioactive isotope package
From The Stargate Omnipedia
Earth technology designed to mimic the energy emitted by Sodan cloaking devices, and thus repel extradimensional parasites. When used in concert with one another, any animal manipulated by these parasites can be repelled or even contained inside a specific radius.
KEY EPISODE
Uninvited - General Landry instructs his team to deposit a circle of radioactive isotope packages around Silver Creek Park, ensuring any extradimensional-parasite-manipulated animal will not be able to escape.