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this is simple.

what i actually want to ask is, when they do the subatomic particle collision experiments, how do they produce one single subatomic particle, e.g proton, neutron? how do they rip one single electron or photon off something? where do they store the single particle?

still, how do they keep the subatomic particle on track, on the designed trajectory?

even further, how do they make sure 2 such small particles to have a head-on collision? it's really a long shot, for they are incredibly small. how do they aim?

share|cite|improve this question is an excellent popular science level introduction – John Rennie Jul 5 '13 at 7:23

When physicists perform particle collisions, they do not execute them one collision at a time. Rather, they perform millions of collisions within very short time frames and they use state of the art computers to analyze and decipher the copious amounts of data they receive.

That being said, to isolate a particle such as a proton, it is as simple as ionizing Hydrogen gas because a Hydrogen is one electron and one proton.

And to your last two questions, they aim the beams of particles (not single particles) at each other with magnets because charged particles bend in magnetic fields. By fine tuning these magnetic fields, they can aim the beams in the precise positions to produce collisions.

share|cite|improve this answer
"they do not execute them one collision at a time" It really depends on the machine in question. While the detector systems at the LHC (ATLAS, CMS, Belle ...) can handle high multiplicity events and the main Tevatron detectors could handle a moderate degree of overlap the further back you go in time the more primitive the state of the art in data acquisition systems get and the low rate they could handle (with some exceptions, bubble chamber can take several events at once if you get lucky in the timing). And of course, for less demanding needs we often build less expensive systems. – dmckee Jul 5 '13 at 14:02

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