question:  Given the information in the article, what is the purpose of a Geiger counter?
context: Then, remembering the dream, he added, “Oh, Dad, is it all right if I use the Geiger counter today?” “You may use the Geiger counter any time you want, Eddie,” Mr. Taylor said, “as long as you take good care of it. Suddenly the Geiger counter began clicking like everything.” But, from what I hear, there are plenty of rock formations. Still, one clue is as good as another when it comes to hunting uranium ore, I guess. It could start cavities. Get at it right away, and you’ll still have time to hunt your uranium. In fact, anything having to do with atomic science excited him. You couldn’t have a father who was head of the atomic-science department at Oceanview College without picking up a little knowledge along the way. Eddie knew that a radioisotope was a material which had been “cooked” in an atomic reactor until it was “hot” with radioactivity. When carefully controlled, the radiation stored up in such isotopes was used in many beneficial ways. One reason for asking that particular question was to keep from prying deeper into the subject of the radioisotope. His father usually volunteered any information he wanted known, so Eddie stuck to questions which could and would be answered. At the speed atomic science is moving today, we simply can’t afford to waste time. “Anything else, Mom?” he asked, returning to the house and getting the Geiger counter out of the closet. Besides, there were plenty of other places around the outskirts of Oceanview where likely looking rock formations invited search with a Geiger counter. They had been ever since Eddie’s family had moved to Oceanview and his father had become head of the college’s atomic-science department. Teena’s father was chief engineer for the Acme Aviation Company, one of the coast town’s largest manufacturing concerns. “Don’t go too far out from town,” Mrs. Ross cautioned, as Eddie picked up the Geiger counter.
output:  To measure for radiation.
options:  To measure rock formation patterns.  To measure for radiation.  To find hidden rocks.  To measure gravity.