Absolute calibration of Beetle1.3 test-pulse, noise and header using MIP signals from an ATLAS reference detector

This paper reports on a study to determine the absolute charge scale of the noise and the test-pulse register of the Beetle1.3 front-end chip used in the context of the LHCb VELO detector. The charge induced in an ATLAS miniature detector by a muon beam is used as a reference. The noise of bonded and unbonded channels, in the scale of Equivalent Noise Charge (ENC), is determined. Furthermore, the reference signal is compared to the signal from the internal test pulses, giving a relation between the register values of the test-pulse DAC and the signal height.