Optimization of multi-gigabit transceivers for high speed data communication links in HEP Experiments

The scheme of the data acquisition (DAQ) architecture in High Energy Physics (HEP) experiments consist of data transport from the front-end electronics (FEE) of the online detectors to the readout units (RU), which perform online processing of the data, and then to the data storage for offline analysis. With major upgrades of the Large Hadron Collider (LHC) experiments at CERN, the data transmission rates in the DAQ systems are expected to reach a few TB/sec within the next few years. These high rates are normally associated with the increase in the high-frequency losses, which lead to distortion in the detected signal and degradation of signal integrity. To address this, we have developed an optimization technique of the multi-gigabit transceiver (MGT) and implemented it on the state-of-the-art 20nm Arria-10 FPGA manufactured by Intel Inc. The setup has been validated for three available high-speed data transmission protocols, namely, GBT, TTC-PON and 10 Gbps Ethernet. The improvement in the signal integrity is gauged by two metrics, the Bit Error Rate (BER) and the Eye Diagram. It is observed that the technique improves the signal integrity and reduces BER. The test results and the improvements in the metrics of signal integrity for different link speeds are presented and discussed

Peak Trekking of Hierarchy Mountain for the Detection of Cerebral Aneurysm using Modified Hough Circle Transform

The Circle of Willis is in the junction of two carotid arteries and two vertebral arteries that supply the brain with nutrition. Junctions where these arteries come together may develop weak spots that can balloon out and fill with blood, creating aneurysms. These sac-like areas may leak or rupture, spilling blood into surrounding tissues which may cause artery spasm leading to potential stroke or even death. Clipping and coiling are two treatment options preferred by neurosurgeon which require proper detection of aneurysm. Medical practitioners are therefore emphasizing on the prior detection of cerebral aneurysm (CA) before rupture occurs leading to subarachnoid haemorrhage (SAH). This paper presents a novel method by application of Modified Hough Circle Transform & Peak Trekking (MHCT-PT) technique on the image extracted from Digital subtraction angiography (DSA). Experimental results have firmly substantiated that the proposed method is highly efficient in properly detecting the location, size and type of aneurysm

Peak Trekking of Hierarchy Mountain for the Detection of Cerebral Aneurysm using Modified Hough Circle Transform

The Circle of Willis is in the junction of two carotid arteries and two vertebral arteries that supply the brain with nutrition. Junctions where these arteries come together may develop weak spots that can balloon out and fill with blood, creating aneurysms. These sac-like areas may leak or rupture, spilling blood into surrounding tissues which may cause artery spasm leading to potential stroke or even death. Clipping and coiling are two treatment options preferred by neurosurgeon which require proper detection of aneurysm. Medical practitioners are therefore emphasizing on the prior detection of cerebral aneurysm (CA) before rupture occurs leading to subarachnoid haemorrhage (SAH). This paper presents a novel method by application of Modified Hough Circle Transform & Peak Trekking (MHCT-PT) technique on the image extracted from Digital subtraction angiography (DSA). Experimental results have firmly substantiated that the proposed method is highly efficient in properly detecting the location, size and type of aneurysm

Optimization of multi-gigabit transceivers for high speed data communication links in HEP Experiments

The scheme of the data acquisition (DAQ) architecture in High Energy Physics (HEP) experiments consist of data transport from the front-end electronics (FEE) of the online detectors to the readout units (RU), which perform online processing of the data, and then to the data storage for offline analysis. With major upgrades of the Large Hadron Collider (LHC) experiments at CERN, the data transmission rates in the DAQ systems are expected to reach a few TB/sec within the next few years. These high rates are normally associated with the increase in the high-frequency losses, which lead to distortion in the detected signal and degradation of signal integrity. To address this, we have developed an optimization technique of the multi-gigabit transceiver (MGT) and implemented it on the state-of-the-art 20nm Arria-10 FPGA manufactured by Intel Inc. The setup has been validated for three available high-speed data transmission protocols, namely, GBT, TTC-PON and 10 Gbps Ethernet. The improvement in the signal integrity is gauged by two metrics, the Bit Error Rate (BER) and the Eye Diagram. It is observed that the technique improves the signal integrity and reduces BER. The test results and the improvements in the metrics of signal integrity for different link speeds are presented and discussed

Trigger and Timing Distributions using the TTC-PON and GBT Bridge Connection in ALICE for the LHC Run 3 Upgrade

The ALICE experiment at CERN is preparing for a major upgrade for the third phase of data taking run (Run 3), when the high luminosity phase of the Large Hadron Collider (LHC) starts. The increase in the beam luminosity will result in high interaction rate causing the data acquisition rate to exceed 3 TB/sec. In order to acquire data for all the events and to handle the increased data rate, a transition in the readout electronics architecture from the triggered to the trigger-less acquisition mode is required. In this new architecture, a dedicated electronics block called the Common Readout Unit (CRU) is defined to act as a nodal communication point for detector data aggregation and as a distribution point for timing, trigger and control (TTC) information. TTC information in the upgraded triggerless readout architecture uses two asynchronous high-speed serial links connections: the TTC-PON and the GBT. We have carried out a study to evaluate the quality of the embedded timing signals forwarded by the CRU to the connected electronics using the TTC-PON and GBT bridge connection. We have used four performance metrics to characterize the communication bridge: (a)the latency added by the firmware logic, (b)the jitter cleaning effect of the PLL on the timing signal, (c)BER analysis for quantitative measurement of signal quality, and (d)the effect of optical transceivers parameter settings on the signal strength. Reliability study of the bridge connection in maintaining the phase consistency of timing signals is conducted by performing multiple iterations of power on/off cycle, firmware upgrade and reset assertion/de-assertion cycle (PFR cycle). The test results are presented and discussed concerning the performance of the TTC-PON and GBT bridge communication chain using the CRU prototype and its compliance with the ALICE timing requirements

Event-shape engineering for inclusive spectra and elliptic flow in Pb-Pb collisions at root(NN)-N-S=2.76 TeV

Peer reviewe

Production of He-4 and (4) in Pb-Pb collisions at root(NN)-N-S=2.76 TeV at the LHC

Results on the production of He-4 and (4) nuclei in Pb-Pb collisions at root(NN)-N-S = 2.76 TeV in the rapidity range vertical bar y vertical bar <1, using the ALICE detector, are presented in this paper. The rapidity densities corresponding to 0-10% central events are found to be dN/dy4(He) = (0.8 +/- 0.4 (stat) +/- 0.3 (syst)) x 10(-6) and dN/dy4 = (1.1 +/- 0.4 (stat) +/- 0.2 (syst)) x 10(-6), respectively. This is in agreement with the statistical thermal model expectation assuming the same chemical freeze-out temperature (T-chem = 156 MeV) as for light hadrons. The measured ratio of (4)/He-4 is 1.4 +/- 0.8 (stat) +/- 0.5 (syst). (C) 2018 Published by Elsevier B.V.Peer reviewe

Electronic system for the ALICE high rate detector upgrade

A Large Ion Collider Experiment (ALICE) is one of the four major high energy physics experiments hosted at the European nuclear research laboratory of CERN, situated in Geneva, Switzerland. CERN houses the world’s most powerful particle accelerator the Large Hadron Collider (LHC). ALICE detector uses the LHC for studying the properties of the hadronic matter at high-temperature in the constituent state of Quark-Gluon plasma (QGP). From 2023 onwards the LHC is starting its RUN3 with an increased luminosity and collision rate. ALICE is going to witnesses a massive upsurge in data volume rate with an estimated value of 3.6 TB/s. To cope with the load of the readout data distribution, a dedicated data balancing electronic system is defined called the Common Readout Unit (CRU). The CRU is at the heart of the ALICE electronic system, whose primary responsibility is to distribute trigger and timing information, to aggregate raw readout data from the sub-detectors on to few manageable links and to moderate the flow of control signals among the various sub-systems. The CRU for its multi-functional role shares a common interface connection with the major neighbourhood electronic systems, namely the Detector-Specific Read Out (DSRO) electronics, the Online-Offline (O2) computing facility and the Central Trigger Processor (CTP). Different interface standards are used for data flow at the different stages. These include the Gigabit Transceiver (GBT) optical link; the Timing, Trigger and Control over Passive Optical Networks (TTC-PON); and the Peripheral Component Interconnect Express (PCIe). The firmware for CRU is implemented on the PCIe40, an Intel® Arria® 10 FPGA based DAQ engine. The dissertation work aims at the study of the CRU design architecture and the associated firmware development for the different interface links and their behaviours. The critical among them is the interface link bridge between the GBT and the TTC-PON. The pathway between the two involves the transmission of the trigger and timing information. Detailed characterisation tests are conducted to ensure the link chain is deterministic and does not involve any point of systematic uncertainty. The link chain involves multiple transition points, hence checked for the behaviour of the stochastic noises. The interference effect of the channel noise on the timing signal as jitter is evaluated. Inline jitter cleaning PLL is used to keep the jitter within the tolerable range as allowed in the ALICE experiment. Impact of temperature variation on the PLL jitter-cleaning ability is also investigated. Apart from the detailed engineering work discussed related to the CRU development, four auxiliary developments that have branched out of the CRU design necessities are embodied in the dissertation work. Firstly, the development of a phase measurement system having resolution and precision in the range of few picoseconds is covered. The sophisticated instrumentation method developed allows the measurement of the phase value inside the FPGA itself without the requirement for other external hardware. Secondly, the need of cyclic redundancy checksum to check for the detector specific data integrity within the CRU is elaborated. The parameters of the design are runtime configurable with the ability to work on a data rate of over 10 Gbps having the processing latency of a unit clock cycle. Thirdly, is the prototype of a secure error resilient protocol having better security and resilience than other frequently used interfaces. Fourthly, a futuristic design solution termed as the Data Aggregation Unit (DAU) is proposed. The idea of DAU is as fundamental as the router itself and highlights the necessity for defining conventional standards for a data balancing block in the high energy physics experiments. In a nutshell, the dissertation discusses the journey of the ALICE detector towards RUN3 that involves the evolution of a new electronic system called the CRU. The engineering work and the other related development during the CRU hardware design implementations are covered. The dissertation closes with an idea for a futuristic design solution of a generic hardware architecture that would be suitable for upcoming mesh based readout framework and allows vertical transitions of the current CRU design

Common Readout System in ALICE

The ALICE experiment at the CERN Large Hadron Collider is going for a major physics upgrade in 2018. This upgrade is necessary for getting high statistics and high precision measurement for probing into rare physics channels needed to understand the dynamics of the condensed phase of QCD. The high interaction rate and the large event size in the upgraded detectors will result in an experimental data flow traffic of about 1 TB/s from the detectors to the on-line computing system. A dedicated Common Readout Unit (CRU) is proposed for data concentration, multiplexing, and trigger distribution. CRU, as common interface unit, handles timing, data and control signals between on-detector systems and online-offline computing system. An overview of the CRU architecture is presented in this manuscript