A SEQUENTIAL PROCESSING STRATEGY FOR THE ATLAS EVENT SELECTION

A new processing strategy for the ATLAS event selection system is prop osed for use downstream of the first level trigger. It aims to achieve a reduction of the event rate to a level suitable for recording on pe rmanent storage via a sequential treatment of the ''regions of interes t'' selected by the level 1 trigger. A possible Trigger/DAQ architectu re which exploits this concept is presented. It is based on a single p rocessing farm and a network which transports data and protocol traffi c. The resources necessary for the implementation of this architecture are estimated. A set of performance figures obtained by calculations and computer simulations are given assuming the use of ATM networking technology.