Speakers
Description
We present first imaging results of our in-house developed muon hodoscopes that are based on modular drift chambers being operated with ArCO2 gas mixture. The basic design is provided by two oppositely arranged printed circuited boards (PCBs) forming an optimized homogeneous drift field volume [1] with a drift length and width of 250 mm, respectively. The chamber height of 10 mm, i.e. the distance between both PCBs, is realized by printed polyamide frames that additionally provide an integrated ionization gas inlet and outlet. Because of its quadratic shape multiple drift chambers can be stacked together to enable three-dimensional muon path investigations.
Therefore, six drift chambers for x- and y-direction each are used to assemble a single muon hodoscope. All twelve drift chambers are successively arranged in a continuously rotated sequence to each other to achieve an interlaced stack of chambers with drift directions +x, +y, -x and -y. Together with a scintillation detector of similar active area at the top or bottom of such stacks is what we call a hodoscope. In that way, a hodoscope height of about 300 mm is achieved as well as highest measurement accuracy achievable. Furthermore, the alternately arranged opposite drift directions avoid systematic error in muon path determination if a more or less undisturbed, i.e. straight, muon passage is assumed. Another advantage of that stack design is the applied daisy-chain connection of the operating voltages for the drifting fields and anode wires along both interlaced drift chamber stacks. Finally, a base plate provides connections for drift chamber signal collection.
With two identical hodoscopes single lead objects and more complex objects, such as STYRODUR® and reinforcing steel embedded in concrete, have been investigated to evaluate the application of these muon hodoscopes for non-destructive investigations, e.g. at bridges and dams.
[1] Bieberle, A.; Wolf, J. F.; Eisenhofer, S. M.; Hampel, U.; Wagner, M “Investigations on a robust single wire drift chamber design for modular muon imaging applications” Nucl. Inst. and Meth. in Physics Res. A, accepted (Feb. 2026).
This work was funded by the Helmholtz Association (Germany) with the grant number KA-TVP-37.