Venus Buckwalter, age 16, of Merrillville, Ind., for her question:

WHAT IS A CYCLOTRON?

A cyclotron is a particle accelerator, or atom¬ smashing machine, invented in 1930 by an American physicist named Ernest 0. Lawrence. It was his idea that a charged particle such as a proton, instead of accelerating in a straight line, could be bent into a circular path by the action of an intense magnetic field.

Cyclotrons are used to accelerate helium nuclei to as high as 50 million electron volts (me v) and the nuclei of heavy hydrogen to 25 me v. Extremely heavy ions may be accelerated up to 200 me v.

These particles can be made to emerge from the cyclotron as a beam. When they bombard various elements, they produce radioisotopes.