The EVA trigger: Transverse momentum selection in a solenoid

J. Wu, E. D. Minor, J. E. Passaneau, S. F. Heppelmann, Chu Ng, G. Bunce, I. Mardor

Research output: Contribution to journalArticlepeer-review

13 Scopus citations


A custom CMOS LSI and ECL PAL-based trigger system for a particle physics experiment is presented. The EVA apparatus at Brookhaven National Laboratory is designed to observe large angle scattering near the kinematic limit of PT for hadron-proton scattering with cross sections in the picobarn range and interaction rates of 100 MHz. The trigger selects events with high PT tracks in a solenoidal straw tube tracking magnetic spectrometer in three stages. An ECL PAL scintillation hodoscope pretrigger and timing mask is followed by PT reconstruction from three superlayers of straw tube drift chambers using custom CMOS LSI integrated circuits. The higher level CMOS trigger system is implemented on custom modules and functions at secondary trigger rates in excess of 1 MHz. A Motorola MC68000 microprocessor resides on each module and uses global information on the event to provide a third trigger level. The modules are interfaced to VMEbus, controlled by a single board VME computer.

Original languageEnglish (US)
Pages (from-to)183-196
Number of pages14
JournalNuclear Inst. and Methods in Physics Research, A
Issue number1
StatePublished - Sep 15 1994

All Science Journal Classification (ASJC) codes

  • Nuclear and High Energy Physics
  • Instrumentation


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