Proportional Wire Chamber
A proportional wire chamber (PWC) is constructed with alternating planes of high voltage wires and sense wires, which are held at ground potential. All the wires are placed in a 80% Ar and 20% CO2 gas environment. When a charged particle passes through gas mixture in the chamber, it ionizes the gas molecules. The resulting ions and electrons are accelerated by the electric field around the wire, causing a localized cascade of ionization which is collected on the wire and results in an electric current proportional to the energy of the detected particle. The PWC produced electronic signals from particle detection allowing scientists to examine data in the DAS.
Each detector station is comprised of a stack of 4 units with an 800 lb steel plate between the 3rd and 4th unit (seen behind the red I-beam in the picture to the left). In total, there are 8 planes of proportional wire chambers (PWCs) placed in a horizontal plane arranged vertically above each other with four planes measuring angles in the east-up plane and four in the north-up plane.
The wires in the PWCs connect to the green circuit boards which process the signals.
Calvin Swartzendruber explains the PWC to a group of students. This PWC is broken and opened up so the wires (and the broken glass) can be easily seen.
InsidePWC2019.MOVThis temperature/humidity chart recorder helps identify issues inside the hut. A stable, moderate temperature and humidity will keep the PWCs working properly.
