Study of transmission-line impedance of strip lines in an MRPC detector

Characteristic impedance study of differential transmission lines based on Digital Sampling Oscilloscope is carried out, and more than 72 multi-gap resistive plate chambers (MRPC) with different structures have been developed and tested. The results show that the impedance is related to the overall electromagnetic field structure, which is determined by the number and width of gas gaps and glass, the number of stacks, and the width of signal strips. The equivalent dielectric constant of the dielectrics between the paired readout strips has been introduced and applied into Wheeler’s equations. After that, the outcome of the equations corresponds with the test results. In addition, a new approximate formula for calculating the transmission-line impedance of multi-stack MRPC detectors is proposed. The values computed from the formula show a good agreement with the experimental data, thus demonstrating its validity.