The Level 0 Trigger Processor for the NA62 experiment Chiozzi, S.; Gamberini, E.; Gianoli, A. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
07/2016, Letnik:
824
Journal Article
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In the NA62 experiment at CERN, the intense flux of particles requires a high-performance trigger for the data acquisition system. A Level 0 Trigger Processor (L0TP) was realized, performing the ...event selection based on trigger primitives coming from sub-detectors and reducing the trigger rate from 10 to 1MHz. The L0TP is based on a commercial FPGA device and has been implemented in two different solutions. The performance of the two systems are highlighted and compared.
The Gigatracker, the silicon beam tracker for the NA62 experiment at CERN Federici, L.; Aglieri Rinella, G.; Alvarez Feito, D. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
04/2020, Letnik:
958
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The Gigatracker is the NA62 beam tracker. It is made of three 63.1mm×29.3mm stations of 300μm×300μm hybrid silicon pixel detectors installed in vacuum (∼10−6mbar). The beam particles, flowing at ...750MHz, are traced in 4-dimensions by mean of time-stamping pixels with a design resolution of 200ps. This performance has to be maintained despite the beam irradiation amounting to a yearly fluence of 2×10141MeVneq∕cm2. The detector material minimization is paramount, as the detector faces the full beam. The station material budget is reduced to 0.5%X0 by using (HEP world first) micro-channels cooling. We will describe the detector design and performances during the NA62 runs.
The Gigatracker detector of the NA62 experiment at CERN SPS Federici, L.; Aglieri Rinella, G.; Alvarez Feito, D. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
08/2019, Letnik:
936
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The NA62 experiment at the CERN SPS is a fixed target experiment designed to measure the branching ratio of the ultra-rare Kaon decay K+→π+νν̄. The experiment uses an high-momentum K+ decay in-flight ...technique to increase the rejection power of the main background: K+→π+π0.
The Gigatracker is a hybrid silicon pixel detector, exposed to a 750 MHz high-energy charged hadron beam, built to give an accurate measurement of K+ momentum and direction together with an high precision measurement of the beam particle arrival time (115 ps RMS resolution per plane). It comprises three stations placed right before the K+ decay region and inserted around two achromats. The detector works in vacuum (∼10−6mbar) at about −10°C.
Each station is made of a 200μm thick silicon sensor readout by 10 TDCPix, custom 100μm thick ASICs, and cooled by an innovative double circuit silicon micro-channel cooling system. All these parts are designed to minimize the total material budget which, in the final detector, amounts to less than 1.5% X0 for the three stations.
In order to sustain the high rate of incoming particles, each TDCPix, operating in a self triggered mode, is equipped with four 3.2 Gb/s serializers sending data to the detector DAQ system based on a read-out card per TDCPix chip sending trigger-matched hits to 6 PC servers. I will describe the whole detector and present some of the results from data collected during the 2016 NA62 runs.
The NA62 GigaTracker Aglieri Rinella, G.; Feito, D. Alvarez; Arcidiacono, R. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
02/2017, Letnik:
845
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The GigaTracker is a hybrid silicon pixel detector built for the NA62 experiment aiming at measuring the branching fraction of the ultra-rare kaon decay K+→π+νν¯ at the CERN SPS. The detector has to ...track particles in a beam with a flux reaching 1.3MHz/mm2 and provide single-hit timing with 200ps RMS resolution for a total material budget of less than 0.5% X0 per station. The tracker comprises three 60.8mm×27mm stations installed in vacuum (∼10−6mbar) and cooled with liquid C6F14 circulating through micro-channels etched inside a few hundred micron thick silicon plates. Each station is composed of a 200μm thick silicon sensor read out by 2×5 custom 100μm thick ASICs, called TDCPix. Each chip contains 40×45 asynchronous pixels, 300μm×300μm each and is instrumented with 100ps bin time-to-digital converters. In order to cope with the high rate, the TDCPix is equipped with four 3.2Gb/s serialisers sending out the data. We will describe the detector and the results from the 2014 and 2015 NA62 runs.
Micro Pattern Gas Detectors (MPGD) are the new frontier in gas trackers. Among this kind of devices, the Gas Electron Multiplier (GEM) chambers are widely used. The experimental signals acquired with ...the detector must obviously be reconstructed and analysed. In this contribution, a new offline software to perform reconstruction, alignment and analysis on the data collected with APV-25 and TIGER ASICs will be presented. GRAAL (Gem Reconstruction And Analysis Library) is able to measure the performance of a MPGD detector with a strip segmented anode (presently). The code is divided in three parts: reconstruction, where the hits are digitized and clusterized; tracking, where a procedure fits the points from the tracking system and uses that information to align the chamber with rotations and shifts; analysis, where the performance is evaluated (e.g. efficiency, spatial resolution,etc.). The user must set the geometry of the setup and then the program returns automatically the analysis results, taking care of different conditions of gas mixture, electric field, magnetic field, geometries, strip orientation, dead strip, misalignment and many others.
The experiment BESIII, running at the accelerator BEPCII in Beijing (P.R.C.), is going to be updated with the replacement of the Inner Drift Chamber with a Cylindrical triple-GEM Inner Tracker ...(CGEM-IT). In the R&D stage, two standalone C++ codes were implemented: GTS (Garfield-based Triple-GEM Simulator), for digitization and tuning of simulated data to the experimental ones, and GRAAL (GEM Reconstruction And Analysis Library), for the reconstruction and analysis of the experimental events collected in testbeams. GTS simulates the triple-GEM response to the particle passage, treating each stage separately: ionization, GEM properties, gas mixture, magnetic field and finally the induction of the signal on the anode. The necessary information was extracted by GARFIELD++ simulations, parametrized and used as input in GTS. This speeds up the simulation, since GTS performs only samplings instead of the full digitization chain. The simulated events were reconstructed with the same procedure used for experimental data and tuning factors were evaluated to obtain a satisfactory match. GRAAL is used in the analysis of the testbeam experimental data. It provides several levels of reconstruction: from the cluster formation, gathering contiguous firing strips, to the spatial position and the signal time reconstruciton. Two algorithms are used: the charge centroid and the micro-TPC, which exploit the charge deposition on the strips and the time information. Also a merging of the two algorithms is available to efficiently weight the two outcomes and obtain the best estimate of the spatial coordinate. Moreover, GRAAL performs tracking and alignment. Both codes are going to be made available also for other MPGDs simulation and reconstruction.
Graphical processors for HEP trigger systems Ammendola, R.; Biagioni, A.; Chiozzi, S. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
02/2017, Letnik:
845
Journal Article
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General-purpose computing on GPUs is emerging as a new paradigm in several fields of science, although so far applications have been tailored to employ GPUs as accelerators in offline computations. ...With the steady decrease of GPU latencies and the increase in link and memory throughputs, time is ripe for real-time applications using GPUs in high-energy physics data acquisition and trigger systems. We will discuss the use of online parallel computing on GPUs for synchronous low level trigger systems, focusing on tests performed on the trigger of the CERN NA62 experiment. Latencies of all components need analysing, networking being the most critical. To keep it under control, we envisioned NaNet, an FPGA-based PCIe Network Interface Card (NIC) enabling GPUDirect connection. Moreover, we discuss how specific trigger algorithms can be parallelised and thus benefit from a GPU implementation, in terms of increased execution speed. Such improvements are particularly relevant for the foreseen LHC luminosity upgrade where highly selective algorithms will be crucial to maintain sustainable trigger rates with very high pileup.
Triple-GEM detectors are a well known technology in high energy physics. In order to have a complete understanding of their behavior, in parallel with on beam testing, a Monte Carlo code has to be ...developed to simulate their response to the passage of particles. The software must take into account all the physical processes involved from the primary ionization up to the signal formation, e.g. the avalanche multiplication and the effect of the diffusion on the electrons. In the case of gas detectors, existing software such as Garfield already perform a very detailed simulation but are CPU time consuming. A description of a reliable but faster simulation is presented here: it uses a parametric description of the variables of interest obtained by suitable preliminary Garfield simulations and tuned to the test beam data. It can reproduce the real values of the charge measured by the strip, needed to reconstruct the position with the Charge Centroid method. In addition, particular attention was put to the simulation of the timing information, which permits to apply also the micro-Time Projection Chamber position reconstruction, for the first time on a triple-GEM. A comparison between simulation and experimental values of some sentinel variables in different conditions of magnetic field, high voltage settings and incident angle will be shown.
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