The selection chain was improved with appropriate electronics in terms of acquisition speed (800Gbps/card) and data processing. The LAPP team has designed a whole new type of cards, named LATOME, which calculates the energy and time of arrival of signals coming from supercells (trigger signal that arrives from the Front-End cards), before transmitting them to the ATLAS trigger system.
For the development phase, the LAPP worked on a demonstrator (ABBA) to validate a certain number of points, in particular the possibility of receiving and sending back data at such rate, the ability to perform the calculations in the allotted time and to master the ATCA standard (standard of electronic systems widely used for telecommunications). This demonstrator was installed on the detector in 2013 and collected data during Run 2 (2015-2018). It was able to receive and transmit data on 24 optical fibers simultaneously, with a rate of 8.5 Gigabits per second.
Following the success of the demonstrator implementation, the ATLAS group of LAPP has developed the cards called LATOME - in reference to a famous Savoyard cheese, the Tome des Bauges - which is capable of processing data at this very high rate, close to 25Tb/s. In 2019, 150 cards were produced and tested in the laboratory. They have been installed in the ATCA racks in the counting room located near the ATLAS detector, 100 meters underground. They will remain in service until the end of the HL-LHC program.
The LAPP has also developed the IPMC card which allows control of ATCA chassis cards (including LATOMEs) and which is used by other ATLAS subsystems.
Contact: Emmanuel Sauvan (sauvan@lapp.in2p3.fr)