LEONARDO: A Pan-European Pre-Exascale Supercomputer for HPC and AI applications

A new pre-exascale computer cluster has been designed to foster scientific progress and competitive innovation across European research systems, it is called LEONARDO. This paper describes thegeneral architecture of the system and focuses on the technologies adopted for its GPU-accelerated partition. High density processing elements, fast data movement capabilities and mature software stack collections allow the machine to run intensive workloads in a flexible and scalable way. Scientific applications from traditional High Performance Computing (HPC) as well as emerging Artificial Intelligence (AI) domains can benefit from this large apparatus in terms of time and energy to solution

LEONARDO: A Pan-European Pre-Exascale Supercomputer for HPC and AI Applications

A new pre-exascale computer cluster has been designed to foster scientific progress and competitive innovation across European research systems, it is called LEONARDO. This paper describes the general architecture of the system and focuses on the technologies adopted for its GPU-accelerated partition. High density processing elements, fast data movement capabilities and mature software stack collections allow the machine to run intensive workloads in a flexible and scalable way. Scientific applications from traditional High Performance Computing (HPC) as well as emerging Artificial Intelligence (AI) domains can benefit from this large apparatus in terms of time and energy to solution.Comment: 16 pages, 5 figures, 7 tables, to be published in Journal of Large Scale Research Facilitie

TEXTAROSSA: Towards EXtreme scale Technologies and Accelerators for euROhpc hw/Sw Supercomputing Applications for exascale

International audienceTo achieve high performance and high energy efficiency on near-future exascale computing systems, three key technology gaps needs to be bridged. These gaps include: energy efficiency and thermal control; extreme computation efficiency via HW acceleration and new arithmetics; methods andtools for seamless integration of reconfigurable accelerators in heterogeneous HPC multi-node platforms. TEXTAROSSA aims at tackling this gap through a co-design approach to heterogeneous HPC solutions, supported by the integration and extension of HW and SW IPs, programming models and tools derived from European research

The CLAS12 RICH readout electronics: design, development and test

Una delle pi\`u importanti strutture al mondo per lo studio della natura su scala nucleare e subnucleare \`e il Laboratorio Thomas Jefferson, situato in Virginia negli Stati Uniti d'America (JLAB), il quale ha recentemente rinnovato il suo acceleratore di elettroni (CEBAF, Continuous Electron Beam Accelerator) per raggiungere l'energia di 12 GeV/c. Il principale obiettivo del CEBAF e delle sue quattro sale sperimentali \`e quello di descrivere come le propriet\`a stabili della materia nucleare, quali lo spin semi-intero dei nucleoni, possano essere spiegate in termini dei gradi di libert\`a dei suoi costituenti quali quark e gluoni. Un innovativo rivelatore ad anelli cherenkov (RICH) \`e stato progettato per lo spettrometro di larga accettanza del CEBAF (CLAS12) allo scopo di migliorare l'identificazione adroni carichi presenti nello stato finale delle degli esperimenti di diffusione e contribuire cos\'i alla complessa rappresentazione multidimensionale del modello attuale. La tesi descrive l'apparato basilare di CLAS12 dedito alla identificazione delle particelle e presenta il nuovo RICH insieme alla sua struttura e ai suoi principi di funzionamento. La trattazione mette in evidenza gli aspetti tecnologici innovativi, adottati per soddisfare i requisiti di fisica in modo affidabile, ad un costo accettabile e in tempi compatibili con le operazioni gi\`a calendarizzate. In particolare si sofferma su raffinate valvole fotomoltiplicatrici multianodiche sensibili al singolo fotone (MAPMT) e sulla elettronica di lettura loro associata che \'e stata appositamente sviluppata nell'ambito della progetto di tesi e la cui validazione ha costituito la maggior mole del lavoro. La descrizione dei circuiti di processamento del segnale, sia analogici che digitali, precede la presentazione delle funzionalit\`a del sistema e la descrizione di come questo sar\`a integrato nella sofisticata architettura di acquisizione dati di CLAS12. Le prove condotte su banco con generatori di impulsi dimostrano una eccellente sensibilit\`a per segnali la cui ampiezza sia grande solo qualche percento di quella del segnale medio corripondente al singolo fotone. Inoltre sono state utili a sviluppare gli algoritmi di correzione della risposta temporale la cui precisione pu\`o raggiungere il nanonsecondo sull'intero intervallo in carica prodotto dai sensori. Ulteriori prove con i MAPMT ed una sorgente laser hanno permesso di verificare le prestazioni dell'intera catena, consentito di ottimizzare le procedure e di portare a compimento lo sviluppo della libreria software. I risultati ottenuti dimostrano la capacit\`a del sistema di accedere alla fenomenologia dei sensori con grande dettaglio (e.g. il crosstalk ottico ovvero la separazione della valanga elettronica tra pixel vicini). Tali peculiari\`a saranno sfruttate durante il ciclo di vita dell'esperimento per controllare lo stato del rivelatore e calibrare i parametri di configurazione utilizzando anche le emissioni termiche dette correnti di buio. Gli argomenti sono presentati con ordine di complessit\`a crescente con l'ultima parte della tesi dedicata alle prove in condizioni reali. I risultati della campagna di validazione condotta per stabilire la tolleranza alle radiazione delle schede elettroniche cos\'i come i veri e propri esperimenti realizzati con prototipi del RICH di piccola scala sono presentati alla fine. In conclusione la elettronica sviluppata per il nuovo RICH di CLAS12 \`e stata progettata, realizzata e validata per il suo scopo. Le sue caratteristiche di compattezza, sensibilit\`a e precisione temporale sono potenzialmente interessanti per altre applicazione di imaging in settori diversi quali lo sviluppo di nuovi rivelatori e la medicina nucleare.One of the world leading facilities for the study of nature at nuclear and sub-nuclear scales is the Thomas Jefferson Laboratory in Virginia, USA (JLAB) where the Continuous Electron Beam Accelerator Facility (CEBAF) has been recently upgraded to reach 12 GeV energy. The main objective of CEBAF and its four experimental halls is to investigate how the stable properties of the matter, like the semi-integer spin of the nucleons, can be explained in terms of degrees of freedom of its constituents, quarks and gluons. An innovative Ring Imaging Cherenkov detector (RICH) has been designed for the CEBAF Large Acceptance Spectrometer (CLAS12) to improve the identification of the charged hadrons produced in the final state of scattering experiments and help in the representation of the complex multi-dimensional structure of the current model. The thesis describes the CLAS12 baseline particle identification system and introduces the new RICH module together with its layout and its operating principles. The dissertation highlights the innovative technological aspects adopted to satisfy the physics requirements at a reasonable cost, in a timely manner and to fit in spectrometer with minimum impact. In particular the thesis treats the single photon sensitive Multi Anode PhotoMultiplier Tubes (MAPMT) and associated custom electronics that has been developed in the thesis project and whose validation has constituted the largest effort of the thesis work. The description of the analog and digital signal processing circuits proceeds the presentation of the functionalities of system the description of its integration in the CLAS12 data acquisition architecture. The tests conducted on bench with pulse generators demonstrate an excellent sensitivity for signal of amplitude just a few percent of the typical photoelectron signal. Moreover they have been used to develop time response correction algorithms that allow to achieve one nanosecond precision over the entire charge interval spanned by the light sensor output. Further tests with MAPMTs and a laser source allowed to verify the full chain performance, optimize the procedures and complete the development of the software library. The obtained results demonstrate the capability of the system to access the detector phenomenology with great detail (e.g. optical crosstalk which is the charge spill over between adjacent pixels). Those peculiarities will be exploited during the life cycle of the experiment to monitor the status of the detector and calibrate the configuration parameters using the dark current of the tubes. The argument are presented in increasing complexity order with the last part dedicated to real condition testing. The results of the validation campaign conducted to asses the radiation tolerance of the electronics board as well the as small scale complete experiment with RICH prototypes are presented in the end. In conclusion the readout electronics of the new RICH of CLAS12 was designed, implemented and validate for its scope. For its compactness, sensitivity and time resolution it can be potentially interesting for other imaging application like the development of new detectors and nuclear medicine

A Characterization System for the Monitoring of ELI-NP Gamma Beam

The ELI-NP (Extreme Light Infrastructure-Nuclear Physics) facility, currently under construction near Bucharest (Romania), is the pillar of the project ELI dedicated to the generation of high-brilliance gamma beams and high-power laser pulses that will be used for frontier research in nuclear physics. To develop an experimental program at the frontiers of the present-day knowledge, two pieces of equipment will be deployed at ELI-NP: a high power laser system consisting of two 10 PW lasers and a high brilliance gamma beam system. The ELI-NP Gamma beam system will deliver an intense gamma beam with unprecedented specifications in terms of photon flux, brilliance and energy bandwidth in an energy range from 0.2 to 20 MeV. Such a gamma beam requires special devices and techniques to measure and monitor the beam parameters during the commissioning and the operational phase. To accomplish this task, the Gamma Beam Characterization System, equipped with four elements, was developed: a Compton spectrometer (CSPEC), to measure and monitor the photon energy spectrum; a nuclear resonant scattering system (NRSS), for absolute beam energy calibration and inter-calibration of the other detectors; a beam profile imager (GPI) to be used for alignment and diagnostics purposes; and finally a sampling calorimeter (GCAL), for a fast combined measurement of the beam average energy and intensity. The combination of the measurements performed by GCAL and CSPEC allows fully characterizing the gamma beam energy distribution and intensity with a precision at the level of few per mill, enough to demonstrate the fulfillment of the required parameters. This article presents an overview of the gamma beam characterization system with focus on these two detectors, which were designed, assembled and are currently under test at INFN-Firenze. The layout and the working principle of the four devices is described, as well as some of the main results of detector test

RED-SEA: Network Solution for Exascale Architectures

In order to enable Exascale computing, next generation interconnection networks must scale to hundreds of thousands of nodes, and must provide features to also allow the HPC, HPDA, and AI applications to reach Exascale, while benefiting from new hardware and software trends. RED-SEA will pave the way to the next generation of European Exascale interconnects, including the next generation of BXI, as follows: (i) specify the new architecture using hardware-software co-design and a set of applications representative of the new terrain of converging HPC, HPDA, and AI; (ii) test, evaluate, and/or implement the new architectural features at multiple levels, according to the nature of each of them, ranging from mathematical analysis and modeling, to simulation, or to emulation or implementation on FPGA testbeds; (iii) enable seamless communication within and between resource clusters, and therefore development of a high-performance low latency gateway, bridging seamlessly with Ethernet; (iv) add efficient network resource management, thus improving congestion resiliency, virtualization, adaptive routing, collective operations; (v) open the interconnect to new kinds of applications and hardware, with enhancements for end-to-end network services - from programming models to reliability, security, low- latency, and new processors; (vi) leverage open standards and compatible APIs to develop innovative reusable libraries and Fabrics management solutions.ISSN:1089-650

Towards EXtreme scale technologies and accelerators for euROhpc hw/Sw supercomputing applications for exascale: The TEXTAROSSA approach

In the near future, Exascale systems will need to bridge three technology gaps to achieve high performance while remaining under tight power constraints: energy efficiency and thermal control; extreme computation efficiency via HW acceleration and new arithmetic; methods and tools for seamless integration of reconfigurable accelerators in heterogeneous HPC multi-node platforms. TEXTAROSSA addresses these gaps through a co-design approach to heterogeneous HPC solutions, supported by the integration and extension of HW and SW IPs, programming models, and tools derived from European research

TEXTAROSSA: Towards EXtreme scale Technologies and Accelerators for euROhpc hw/Sw Supercomputing Applications for exascale

International audienceTo achieve high performance and high energy efficiency on near-future exascale computing systems, three key technology gaps needs to be bridged. These gaps include: energy efficiency and thermal control; extreme computation efficiency via HW acceleration and new arithmetics; methods andtools for seamless integration of reconfigurable accelerators in heterogeneous HPC multi-node platforms. TEXTAROSSA aims at tackling this gap through a co-design approach to heterogeneous HPC solutions, supported by the integration and extension of HW and SW IPs, programming models and tools derived from European research

A search for the K+→μ−νe+e+K^+\to\mu^-\nu e^+e^+ decay

A search for the $K^+\to\mu^-\nu e^+e^+$ decay, forbidden within the Standard Model by either lepton number or lepton flavour conservation depending on the flavour of the emitted neutrino, has been performed using the dataset collected by the NA62 experiment at CERN in 2016--2018. An upper limit of $8.1\times 10^{-11}$ is obtained for the decay branching fraction at 90% CL, improving by a factor of 250 over the previous search

Searches for lepton number violating K+→π−(π0)e+e+K^+\to\pi^-(\pi^0)e^+e^+ decays

Searches for lepton number violating $K^+\to\pi^-e^+e^+$ and $K^+\to\pi^-\pi^0e^+e^+$ decays have been performed using the complete dataset collected by the NA62 experiment at CERN in 2016-2018. Upper limits of $5.3\times 10^{-11}$ and $8.5\times 10^{-10}$ are obtained on the decay branching fractions at 90% confidence level. The former result improves the limit by a factor of four over the previous best limit, while the latter result represents the first limit on the $K^+\to\pi^-\pi^0e^+e^+$ decay rate.Searches for lepton number violating K+→π−e+e+ and K+→π−π0e+e+ decays have been performed using the complete dataset collected by the NA62 experiment at CERN in 2016–2018. Upper limits of 5.3×10−11 and 8.5×10−10 are obtained on the decay branching fractions at 90% confidence level. The former result improves by a factor of four over the previous best limit, while the latter result represents the first limit on the K+→π−π0e+e+ decay rate.Searches for lepton number violating $K^+\to\pi^-e^+e^+$ and $K^+\to\pi^-\pi^0e^+e^+$ decays have been performed using the complete dataset collected by the NA62 experiment at CERN in 2016-2018. Upper limits of $5.3\times 10^{-11}$ and $8.5\times 10^{-10}$ are obtained on the decay branching fractions at 90% confidence level. The former result improves by a factor of four over the previous best limit, while the latter result represents the first limit on the $K^+\to\pi^-\pi^0e^+e^+$ decay rate