The Top Quark

On March 2, 1995, Fermilab announced the discovery of the top quark, the last of the six predicted quarks. The search began in 1977 when physicists found the fifth quark, bottom, at Fermilab. It took this long because the top quark was much more massive than was originally predicted, so it required a more powerful accelerator to create it.

Although the top quark decays too fast to be observed, it does leave behind particles that give record to its existence - a top quark "signature". The top quark can decay in more than one way. Since a top quark appears only once in couple billion collisions does trillions of collisions were necessary.

Physicists still do not understand why the top is so massive. It is 40 times heavier than the next heaviest quark and about 35,000 times heavier than the up and down quarks that make up most of the matter we see around us. In fact the question still remains why anything has mass at all. Physicists hope that the discovery of the top quark will give them insight to these questions.

An Actual Top Event Picture of Top Quark ProductionQuarks

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