50 years ago, Fermilab turned to bubbles

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NAL was renamed Fermilab in 1974 for physicist Enrico Fermi. The lab’s first accelerator produced protons in April 1969, and was shooting subatomic particles into a 76-centimeter bubble chamber filled with liquid hydrogen by 1972. Such chambers track bubble trails left by speeding particles. The lab began upgrading to a 4.5-meter chamber detector in 1973, which helped in the study of neutrinos and turned up evidence for bottom and top quarks. As accelerators modernized, bubble detectors were phased out, and Fermilab’s chamber became an art installation. But SNOLAB’s bubble chamber in Sudbury, Canada, still searches for weakly interacting massive particles, or WIMPS — a proposed type of dark matter.