A Geiger counter is used primarily to measure what?

What is a gap through a mountain range, like Donner, called? What would the Argentine gaucho be called in Texas? Which word names both a gazebo and an outdoor newsstand? Which 1841 ballet has been called "the Hamlet of dance"? A gendarme has which job in France? A genetically engineered version of which produce item went on sale in 1994 under the name Flavr Savr? A génoise is a light, rich variety of which baked good? In which 1955 Disney classic does a genteel cocker spaniel find romance with a mutt from the wrong side of the tracks?