Performance Studies of the Associative Memory System of the ATLAS Fast Tracker

The Associative Memory (AM) system of the Fast Tracker (FTK) processor has been designed to perform pattern matching using the hit information of the ATLAS experiment silicon tracker. The system is one of the two main processing elements of FTK and is mainly based on the use of Application Specific Integrated Circuits, the AM chips, specifically designed to execute pattern matching with a high degree of parallelism. It finds track candidates at low resolution that are seeds for a full resolution track fitting. The AM system implementationis based on a collection of “AM boards”, the “Serial Link Processors” (AMBSLP). The AMBSLP is based on a network of high speed serial links to sustain very high data traffic. It has a high consumption (250 W) because of its high performance requirements and, therefore, the AM system needs custom power and cooling. This paper reports on the performance studies of the system made with the first production of 64 AMBSLPs integrated in FTK and results from the first ATLAS data during 2018.