Related Clues:

• Insignificant amount
• Supercollider projectile
• Sometimes it gets smashed
• Proton's place
• Cyclotron bit
• Teeny bit
• Source of nuclear energy
• Nuclear energy source
• Smallest amount
• Smallest bit
• With 60-Across, 1960's TV cartoon hero
• Slightest trace
• Smashing subject
• Unit of a molecule
• Basic building block