The plastic - aluminum comparison was made in earlier ground - based tests using beams of heavy particles to simulate cosmic rays. (sciencedaily.com)
Direct searches look for the production of new heavy particles in high - energy collisions. (sciencedaily.com)
One is it just produces more particles that we'd like to look at, and it also produces heavier particles that we might not have been able to see before. (scientificamerican.com)