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 fabric ated in TEMIC corporations 0.8-mum DMILL [1] BI-CMOS SOT radiation-hard pro cess for the Large Hadron Collider's (LHC) Transition Radiation Tracker (AT LAS/TRT) at CERN [2]. The chip receives discriminated straw-drift-tube sign als from bipolar amplifier-shaper-discriminator chips (ASDBLR), measures th e arrival time in 3.125-ns increments ( 1 ns), and stores the data in a pip eline for 3.3 mum. 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 o n-chip buffer while data is being clocked out in a 40 MHz serial stream. Th e chip has been designed to function after exposure to 1 x 10(14) protons/c m(2) and 1.0 Mrad total dose. System beam-tests have demonstrated measureme nt of track positions with a resolution of 165 mum and high efficiency at r ates up to 18 MHz.