Cloud chamber particle detector

Sampling Detectors. These consist of tubing distributed from the detector unit into the area(s) to be protected. An air pump draws air from the protected area back to the detector. A high-intensity strobe, laser particle counter, or cloud-chamber smoke detector may be used... 

Ionization and condensation nuclei detectors alarm at the presence of invisible combustion products. Most industrial ionization smoke detectors are of the dual chamber type. One chamber is a sample chamber the other is a reference chamber. Combustion products enter an outer chamber of an ionization detector and disturb the balance between the ionization chambers and trigger a highly sensitive cold cathode tube that causes the alarm. The ionization of the air in the chambers is caused by a radioactive source. Smoke particles impede the ionization process and trigger the alarm. Condensation nuclei detectors operate on the cloud chamber principle, which allows invisible particles to be detected by optical techniques. They are most effective on Class A fires (ordinary combustibles) and Class C fires (electrical). 

In a cloud chamber detector, ions at atmospheric pressure are electrically focused into a cloud chamber filled with cold water or octane vapors. The presence of the ion serves as the nucleus for the formation of small droplets that can scatter light from a laser beam passing through the cloud chamber. When mobility-separated ions entered the cloud chamber, perturbation in the laser light due to the formation of ion-nucleated particles was detected by a PMT. When the chamber was supersaturated with water, the scattered light intensity increased in the presence of ions, but when the chamber was supersaturated with octane, the intensity decreased in the presence of ions. Mobility spectra of difluorodibromomethane have been reported using cloud chamber detection." ... 

Alpha particles may be counted also by gaseous, liquid, plastic, and crystalline scintillation detectors. The resolution of these detectors is. In general, less, than Ionization chambers and their application more limited. Nuclear emulsions are used to record alpha activity. Such devices as cloud chambers are generally not used In the radloehemlatry laboratory. 

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