Response of the APV readout chip to laser-simulated, highly ionizing interactions

Heavily Ionizing Particles are know to cause sizable dead-time in the front end APV chip of the CMS Silicon Strip Tracker. To better understand this behavior, the effects of Highly Ionizing Particles in the CMS Silicon Strip Tracker were simulated using a 1060 nm laser. Calibrated laser pulses allow one to determine the energy threshold at which the dead-time becomes significant as well as the time evolution of the chip response. Various APV settings and supply line resistor values were investigated. Results agree with test beam data as well as previous laboratory measurements in confirming that settings can be found for which the dead-time is as low as 100ns for up to 50 MeV deposited energy.