PLD first level surface detector trigger in the Pierre Auger Observatory

The Pierre Auger Observatory surface array will contain 1600 surface detector stations distributed over 3000 km² on each Southern (Argentina, under construction since 2000) and Northern Site (Utah, planned to be built since 2005). The large area covered, the limited power budget necessitated by solar power operation, the restricted data bandwidth available through the stations´ wireless network connections, and the temperature extremes inherent in an uncontrolled environment, impose special constraints on the surface detector trigger system. Several approaches to the implementation of the first level trigger were pursued during the engineering phase of the project in the lab and in the field. In this paper the Programmable Logic Devices (PLD) solutions, based upon industrial grade Altera® APEX™, ACEX®, Cyclone™ series are presented. The APEX™ design is working successfully on the Engineering Array since December 2000. The ACEX® cost-effective solution has been chosen for the final design, however the Cyclone™ design, as the single chip solution with the best parameters, is still under investigation and is considered either as an improvement option for the Southern Site or as the baseline for the Northern Site.