Construction of a Multi-Wire Proportional Chamber for Cosmic Ray Muon Detection

The Society of Physics Students (SPS) at Kennesaw State University is building a Multi-Wire Proportional Chamber (MWPC) as a tool to detect cosmic ray muons and do muon tomography.

The frame for the chamber was designed in SolidWorks, and is 3D printed in one piece with a Makerbot Ultimaker 2, using PLA, a biodegradable plant-based plastic. The frame was recently redesigned to accommodate a 3/16” diameter o-ring, which will seal the chamber better, and allow the chamber to be opened later if necessary. The ability to open the chamber is useful for basic maintenance on the chambers, and it allows for testing the functionality with other types of sources.

Once the frame is printed, both the sense wires and field-shaping wires needed to be attached and soldered under tension, with spacing between wires of 3 mm. The gold-plated tungsten sense wires are 25 microns in diameter, while the copper field-shaping wires are 100 microns. Since the wires are extremely fine, the process of attaching them is not trivial, so the frame also includes small grooves were added to aid in the alignment of the wires. Once the wires are attached, the chamber is sealed and a potential difference of 2000V is applied to the two different types of wire.