CERN Accelerating science

Article
Title	Readout Firmware of the Vertex Locator for LHCb Run 3 and Beyond
Author(s)	Hennessy, Karol (U. Liverpool (main)) ; Prieto, Antonio Fernandez (Santiago de Compostela U., IGFAE) ; Regueiro, Pablo Vazquez (Santiago de Compostela U., IGFAE) ; Buytaert, Jan (CERN) ; Van Beuzekom, Martin (Nikhef, Amsterdam) ; Cid, Edgar Lemos (Santiago de Compostela U., IGFAE) ; Eklund, Lars (Glasgow U.) ; de Bruyn, Kristof (Nikhef, Amsterdam) ; Naik, Sneha (Glasgow U.) ; Schiller, Manuel (Glasgow U.) ; Murray, Donal (Manchester U.) ; Leflat, Alexander (Moscow State U.) ; Bassi, Giovanni (Pisa, Scuola Normale Superiore) ; Punzi, Giovanni (INFN, Pisa) ; Lazzari, Federico (INFN, Pisa) ; Morello, Michael J (Pisa, Scuola Normale Superiore) ; Garcia, Oscar Boente (Santiago de Compostela U., IGFAE) ; Torreira, Abraham Gallas (Santiago de Compostela U., IGFAE) ; Plana, Beatriz Garcia (Santiago de Compostela U., IGFAE) ; Bowcock, Themis (U. Liverpool (main)) ; Dettori, Francesco (U. Liverpool (main)) ; Dreimanis, Karlis (U. Liverpool (main)) ; Lima, Vinicius Franco (U. Liverpool (main)) ; Hutchcroft, David (U. Liverpool (main)) ; Rinnert, Kurt (U. Liverpool (main)) ; Shears, Tara (U. Liverpool (main)) ; Augusto, Oscar (CERN) ; Coco, Victor (CERN) ; Collins, Paula (CERN) ; Evans, Tim (CERN) ; Ferro-Luzzi, Massi (CERN) ; Schindler, Heinrich (CERN) ; Akiba, Kazu (Nikhef, Amsterdam) ; Occo, Elena Dall' (Nikhef, Amsterdam) ; Graz, Cristina Sanchez (Nikhef, Amsterdam) ; Hulsbergen, Wouter (Nikhef, Amsterdam) ; Hynds, Daniel (Nikhef, Amsterdam) ; Kostiuk, Igor (Nikhef, Amsterdam) ; Merk, Marcel (Nikhef, Amsterdam) ; Snoch, Aleksandra (Nikhef, Amsterdam) ; Bobulska, Dana Seman (Glasgow U.) ; Borghi, Silvia (U. Manchester (main)) ; de Capua, Stefano (U. Manchester (main)) ; Dutta, Deepanwita (U. Manchester (main)) ; Gersabeck, Marco (U. Manchester (main)) ; Parkes, Chris (U. Manchester (main)) ; Svihra, Peter (U. Manchester (main)) ; Williams, Mark (U. Manchester (main)) ; Bogdanova, Galina (Moscow State U.) ; Volkov, Vladimir (Moscow State U.) ; Kopciewicz, Pawel (AGH-UST, Cracow) ; Majewski, Maciej (AGH-UST, Cracow) ; Oblakowska-Mucha, Agnieszka (AGH-UST, Cracow) ; Rachwal, Bartlomej (AGH-UST, Cracow) ; Szumlak, Tomasz (AGH-UST, Cracow) ; Garcia, Lucas Meyer (UFRJ, Rio de Janeiro) ; Marinho, Franciole (UFRJ, Rio de Janeiro) ; Mendes, Larissa Helena (UFRJ, Rio de Janeiro) ; Nasteva, Irina (UFRJ, Rio de Janeiro) ; Otalora, Juan (UFRJ, Rio de Janeiro) ; Rodrigues, Gabriel (UFRJ, Rio de Janeiro) ; Velthuis, Jaap (Bristol U.) ; Jalocha, Pawel (U. Oxford (main)) ; John, Malcolm (U. Oxford (main)) ; Jurik, Nathan (U. Oxford (main)) ; Scantlebury-Smead, Luke (U. Oxford (main)) ; Back, John (Warwick U.) ; Gershon, Tim (Warwick U.) ; Latham, Tom (Warwick U.) ; Morris, Andrew (Warwick U.)
Publication	2021
Number of pages	8
In:	IEEE Trans. Nucl. Sci. 68 (2021) 2472-2479
DOI	10.1109/tns.2021.3085018
Subject category	Computing and Computers ; Detectors and Experimental Techniques
Accelerator/Facility, Experiment	CERN LHC ; LHCb
Abstract	The new LHCb Vertex Locator (VELO) for LHCb, comprising a new pixel detector and readout electronics, will be installed in 2021 for data taking in Run 3 at the LHC. The electronics centers around the “VeloPix” ASIC at the front-end operating in a trigger-less readout at 40MHz. A custom serializer, called gigabit wireline transmitter (GWT), and associated custom protocol have been designed for the VeloPix. The GWT data are sent from the serializers of the VeloPix at a line rate of 5.12 Gb/s, reaching a total data rate of 2–3 Tb/s for the full VELO detector. Data are sent over 300-m optic-fiber links to the control and readout electronics cards for deserialization and processing in Intel Arria 10 FPGAs. Because of the VeloPix trigger-less design, latency variances up to 12 μs can occur between adjacent datagrams. It is therefore essential to buffer and synchronize the data in firmware prior to onward propagation or suffer a huge CPU-processing penalty. This article will describe the architecture of the readout firmware in detail with focus given to the resynchronization mechanism and techniques for cauterization. Issues found during readout commissioning, and scaling resource utilization, along with the their solutions, will be illustrated. The latest results of the firmware data-processing chain can be presented as well as the verification procedures employed in simulation. Challenges for the next generation of the detector will also be presented with ideas for a readout processing solution.
Copyright/License	publication: (License: CC-BY-4.0)

Corresponding record in: Inspire