Progress in the development of the DTMROC time measurement chip for the ATLAS transition radiation tracker (TRT)

A 16-channel digital time-measurement readout chip (DTMROC) has been fabricated in the TEMIC/DM1LL left bracket 1 right bracket BI- CMOS radiation-hard process for the Large Hadron Collider's (LHC) Transition Radiation Tracker (ATLAS/TRT) at CERN left bracket 2 right bracket . The chip receives discriminated straw-drift-tube signals from bipolar amplifier-shaper-discriminator chips (ASDBLR). measures the arrival time in 3.125 ns increments ( plus or minus 1 ns), and stores the data in a pipeline for 3.3mus. A trigger signal (L1A) causes the data to be tagged with a time stamp and stored for readout- Up to 13 events may be stored in an on-chip buffer while data is being clocked out in a 40 MHz serial stream. The chip has been designed to function after exposure to 1x10**1**4 protons/cm**2 and 1 Mrad total dose. System beam-tests have demonstrated measurement of track positions with a resolution of 165mum and 85% efficiency at rates up to 18MHz. 6 Refs.