FELIX: the New Detector Interface for the ATLAS Experiment

Abstract

During the next major shutdown (2019)(2020), the ATLAS experiment at the LHC will adopt the Front-End Link eXchange (FELIX) system as the interface between the data acquisition, detector control and TTC (Timing, Trigger and Control) systems and new or updated trigger and detector front-end electronics. FELIX will function as a router between custom serial links from front-end ASICs and FPGAs to data collection and processing components via a commodity switched network. Links may aggregate many slower links or be a single high bandwidth link. FELIX will also forward the LHC bunchcrossing clock, fixed latency trigger accepts and resets received from the TTC system to front-end electronics. The FELIX system uses commodity server technology in combination with FPGAbased PCIe I/O cards. The FELIX servers will run a software routing platform serving data to network clients. Commodity servers connected to FELIX systems via the same network will run the new Software Readout Driver (SW ROD) infrastructure for event fragment building and buffering, with support for detector or trigger specific data processing, and will serve the data upon request to the ATLAS High Level Trigger for Event Building and Selection. This paper will cover the design and status of FELIX, the SW ROD, results of early performance testing and integration tests with several ATLAS front-ends.

Beneš Network Based Efficient Data Concentrator for Triggerless Data Acquisition Systems

“…That solution requires a more complex data-driven multiplexer, which automatically selects the first input providing the complete data record after the previously serviced one (i.e., it implements the round-robin policy). This approach seems to be used in the firmware for the FELIX board in the ATLAS experiment readout at CERN [7]. Unfortunately, the operation of the data concentrator in the FELIX firmware is not described in detail in any paper.…”

“…swap(&l0 [4],&l0[5],&l1 [2],&l1 [6],isw & (1<<2)); swap(&l0 [6],&l0 [7],&l1 [3],&l1 [7],isw & (1<<3)); //2nd layer of switches swap(&l1[0],&l1 [1],&l2[0],&l2 [2],isw & (1<<4)); swap(&l1 [2],&l1 [3],&l2 [1],&l2 [3],isw & (1<<5)); swap(&l1 [4],&l1[5],&l2 [4],&l2 [6],isw & (1<<6)); swap(&l1 [6],&l1 [7],&l2[5],&l2 [7],isw & (1<<7)); //3rd layer of switches swap(&l2[0],&l2 [1],&l3[0],&l3 [2],isw & (1<<8)); swap(&l2 [2],&l2 [3],&l3 [1],&l3 [3],isw & (1<<9)); swap(&l2 [4],&l2[5],&l3 [4],&l3 [6],isw & (1<<10)); swap(&l2 [6],&l2 [7],&l3[5],&l3 [7],isw & (1<<11)); //4th layer of switches swap(&l3[0],&l3 [1],&l4[0],&l4 [2],isw & (1<<12)); swap(&l3 [2],&l3 [3],&l4 [4],&l4 [6],isw & (1<<13)); swap(&l3 [4],&l3[5],&l4 [1],&l4 [3],isw & (1<<14)); swap(&l3 [6],&l3…”

Frontend and backend electronics for the ATLAS New Small Wheel Upgrade

“…On the back-end of the readout path, lies FELIX. FELIX is an FPGA-based data-routing device, mounted on a board connected to a PCIe slot of a commercial PC [4]. The FPGA board interfaces via optical fiber with the GBTx chips of the front-end, collects the events from the optical links and eventually dumps the received data to the ReadOut Drivers (ROD).…”

Development and test of a mini-Data Acquisition system for the High-Luminosity LHC upgrade of the ATLAS Monitored Drift Tube detector

“…Pattern recognition, segment-finding, and trackfitting algorithms are then applied to determine the muon momentum at the first trigger level. Hit data are stored for transmission to a network called Front End LInk eXchange (FELIX) [19] after receiving the first-level trigger acceptance signal.…”