Evaluation of EMI shielding for particle physics detectors

Providing adequate shielding against electromagnetic interference (EMI) is critical for most particle physics detectors but especially for tracking detectors that sit around a beam pipe of a colliding beam facility and have small signals to detect. It is also critical, however, to minimize the material necessary for this shielding because all material in line with the trajectories of the particles to be detected interferes with those trajectories thus degrading the performance of the tracking detector. We report here the results of a series of tests of popular shielding materials, namely copper, aluminium and carbon fiber, using the line injection method to measure the Transfer Impedance of shields made of these materials as a gauge of their relative shielding quality.