Application of the Beetle Header cross-talk correction algorithm for the VELO Detector

The front-end chip of the VELO detector is known as the Beetle. The data obtained from the VELO strips is proceeded by header bits. The value of these header bits can affect the signal data of the VELO. This causes increased noise on one in every 32 channels of the VELO detector. An algorithm to correct this cross-talk has been implemented in the TELL1 readout board of the VELO detector. The correction coefficients for this algorithm can be calculated through the analysis of non-zero suppressed data in the VELO analysis package VETRA. This note presents a study of this cross-talk effect, an evaluation of the effectiveness of the algorithm implemented, a procedure to calculate the required correction coefficients for the algorithm, and a method to monitor the performance of this algorithm. The algorithm is found to provide suitable compensation on test beam data where significant corrections were required. In the final system, with optimized digitization timing, the corrections required are found to be smaller, typically less than three ADC counts.