Fractional polarization versus the projected distance from the cluster center, normalized by the core radius, for sources in clusters that host a radio halo (left), and that do not host a radio halo (right). Arrows indicate upper limits. Bottom panel: crosses refer to the median of the KM estimator is each bin, bars indicate the 14th and 84th percentile. Due to the low number of points in each bin the width of each bin is adaptively set so that at leat 3 detections fall within a bin.