Development of fast parallel trigger algorithms for the ATLAS experiment at CERN

DOMAIN: Technologies associated to the Portuguese participation at CERN and their transfer to society

SUPERVISOR: Patricia Conde Muino

HOST INSTITUTION: Laboratório de Instrumentação e Física Experimental de Partículas

DEGREE INSTITUTION: Universidade de Lisboa


The LHC is the highest energy particle accelerator ever built. The gigantic ATLAS experiment records proton and ion collisions produced by the LHC to study the most fundamental matter particles and the forces between them. At the nominal rate of the LHC, the proton bunches cross 40 million times per second, producing up to 40 collisions per bunch crossing. This event rate is processed in real time by the ATLAS Trigger and data acquisition system, that analyse the results of the collisions, as registered by the 10^8 electronic channels of the detector to select a maximum rate of about 1000 events/second for further offline storage and analysis. In 2025-26, the LHC will be upgraded to increase the LHC collision rate up to a factor 7, to allow acquiring a huge amount of data and pushing the limits of our understanding of Nature. The collision rate and data volume after the LHC upgrade will impose extreme demands on the ATLAS trigger system. The estimated increase in trigger rates and event size lead to larger data volume and much longer event reconstruction times, that are not matched by the slower expected growth in computing power at fixed cost. This requires a change in paradigm, increasing parallelism in computer architecture, using concurrency and multithreading and/or hardware accelerators, such as GPUs or FPGAs for handling suitable algorithmic code. The objective of this thesis program is develop novel calorimeter clustering and jet reconstruction algorithms using accelerators such as FPGAs or GPUs, for the Phase II Upgrade of the ATLAS Trigger system. The student will work in close collaboration with researchers from LIP computing center and particle physics groups, as well as with colleagues from CERN and other institutions involved in the ATLAS experiment. This work will be developed in an international environment. The student will contribute to the improvement of the jet trigger system of the ATLAS experiment at CERN. Presentations at ATLAS Collaboration meetings are expected, either by video-conferencing or at CERN.

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