& +4 zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA __ 8 _! ; ELSEVIER Nuclear Instruments and Methods in Physics Research A 360 (1995) 314-317 NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SectIon zyxwvutsrqponmlkjih A Tracking triggers for the upgraded D@ detector S. Glenn a, * , P. Bloom ‘, S. Mani a, D. Pellett a, J. Costa ‘, L. Moreira b, A. Baumbaugh ‘, G. Blazey ‘, F. Borcherding ‘, M. Johnson ‘, J. Wilcox d a zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA University of California. Davis, CA, USA ’ CBPF/LAFEX, Rio de Janeiro, Brazil ’ Fermi National Accelerator Laboratory, Batavia, IL, USA d Northeastern lJniuersi& Boston, MA, USA For the DO Collaboration zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONM Abstract The high luminosity environment of the upgraded Tevatron will require not only the upgrade of various DP, subdetectors, but the trigger system as well. With respect to the present system, the upgraded trigger system must operate faster and provide a higher degree of background rejection while extending the physics acceptance beyond that of the current system. This will be accomplished in part by incorporating the scintillating fiber tracker and the preshower detector into the Level 1 trigger. Track logic, implemented in commercial FPGAs, will be used to identify tracks in the scintillating fiber tracker with P, > 1.5 GeV/c and electron candidates in the preshower detector. Integration of the trigger logic and readout electronics permits the identification of all tracks in a few hundred nanoseconds. Here, preliminary designs for the readout and trigger electronics are presented along with simulation results for trigger efficiencies and rejection factors. 1. Introduction The goal of the D0 upgrade program is to simultane- ously extend the physics capability of the detector and adapt it to the high luminosity environment of the up- graded Tevatron. Upgrade plans for the D@ central detec- tor include the replacement of the current nonmagnetic tracking system with a fast high-resolution magnetic track- ing and vertexing system consisting of a silicon microstrip vertex detector (SVX) and a central Scintillating Fiber Tracker (SFT). Additionally, a Preshower Detector (PSD) will be installed to compensate the response of the electro- magnetic calorimeter for the effects of additional material associated with the new tracking system. The fast response of these subdetectors allows the implementation of power- ful first level tracking triggers. A schematic of the DP, central detector upgrade is shown in Fig. 1. The silicon vertex detector consists of barrels and disks which provide coverage out to a radius of 9.2 cm. Outside of the vertex detector is the SFT consist- ing of four superlayers with radii of 20, 30, 40, and 50 cm. Each superlayer consists of four fiber doublet layers: two axial layers and two small angle stereo layers. The two * Corresponding author. Although there are many possible uses for tracking axial layers within the superlayer have a radial separation of 1.5 cm to allow an independent determination of track direction for each superlayer. A 2 T magnetic field is provided by a thin superconducting solenoid which also serves to support the PSD situated between the solenoid and the calorimeter. The PSD is constructed from scintilla- tor of 5 mm width with embedded fiber readout. The total number of combined channels for the SFT and PSD sys- tems is about 90000. 2. Trigger considerations The bunch spacing interval at the upgraded Tevatron may be as low as 132 ns and at a luminosity of 1O32 cm-’ SK’, about 50% of the beam crossings result in one or more interactions. At this luminosity, the task of the Level 1 trigger system will be to reduce the 4 MHz interaction rate to 10 kHz or less which can be accepted by Level 1.5. To achieve this, the SFT trigger will operate at Level “0.5” so that other Level 1 triggers can utilize tracking information to reduce backgrounds. That is, track identifi- cation must be completed within a few hundred nanosec- onds after a Level 0 (inelastic interaction) accept to allow tracking information to be sent to the Level 1 trigger systems well within the 3.5 ps Level 1 latency period. 0168-9002/95/$09.50 0 1995 Elsevier Science B.V. At1 rights reserved SSDI 0168-9002(94)01617-8