PXL timing There are two asynchronous systems. STAR PXL RDO L0 trigger L0 detectors Physics collision Trigger processing TCD distribution 1.5 us TBD RDO board clock/Start MTB buffering Sensor frame begin tx MTB buffering RDO board rx 250 ns* Total Trigger Delay (TTD) 1.75 us * To be verified

PLAN Use an oscilloscope to measure the transit time from the START generated on the RDO board to the receipt of the START on the low mass cable section. Add the time from the Ultimate manual from the receipt of START to the first row processing. The time offset between the send of START from the RDO motherboard (internal time pointer) and the beginning of the first row processing is then TD + FPD This will be done with the production cables, MTB and feedthrough. PXL RDO txMTB buffering Ladder sensor Send start Transit Delay (TD) PXL RDO

LVDS measured on one side of termination resistor. Blue trace – Falling edge of START measured at RDO board R34 Yellow trace – START (opposite polarity) measured on driver board R95 Transit Delay = 79 ns

PXL RDO txMTB buffering Sensor frame begin tx MTB buffering RDO board rx Ladder sensor PXL initial startup timing Send start Ladder sensor Delay until frame starts Delay until past frame header RDO board Serdes processing First frame latency We will measure the full latency through the system from the transmission of the START to the arrival of the first frame header at the RDO board

LVDS measured on one side of termination resistor. Blue trace – falling edge of START measured at RDO board R34 Yellow trace – Sensor1 data output 1 (opposite polarity) measured on RDO board R1. First frame latency = us