Design and Performance of the Data Acquisition System for the NA61/SHINE Experiment at CERN

This paper describes the hardware, firmware and software systems used in data acquisition for the NA61/SHINE experiment at the CERN SPS accelerator. Special emphasis is given to the design parameters of the readout electronics for the 40m^3 volume Time Projection Chamber detectors, as these give the largest contribution to event data among all the subdetectors: events consisting of 8bit ADC values from 256 timeslices of 200k electronic channels are to be read out with ~100Hz rate. The data acquisition system is organized in "push-data mode", i.e. local systems transmit data asynchronously. Techniques of solving subevent synchronization are also discussed.Comment: 14 pages, 13 figure

Characterization of Semiconductor Lasers for Radiation Hard High Speed Transceivers

In the context of the versatile link project, a set of semiconductor lasers were studied and modelled aiming at the optimization of the laser driver circuit. High frequency measurements of the laser diode devices in terms of reflected and transmission characteristics were made and used to support the development of a model that can be applied to study their input impedance characteristics and light modulation properties. Furthermore the interaction between the laser driver, interconnect network and the laser device itself can be studied using this model. Simulation results will be compared to measured data to validate the model and methodology

A Timing, Trigger, and Control System With Picosecond Precision Based on 10 Gbit/s Passive Optical Networks for High-Energy Physics

The Large Hadron Collider (LHC) experiments will have their timing, trigger, and control (TTC) system upgraded as a consequence of the need for higher bandwidth and components which are obsolete. In this article, we present a TTC based on passive optical networks (PONs). TTC-PON is a point-to-multipoint bidirectional TTC system based on the 10 Gbit/s International Telecommunications Union (ITU) XG-PON technology and modern field-programmable gate array (FPGA) devices. Each master can handle up to 64 slaves through a fully passive network, delivering a fixed-phase recovered clock to all the destinations with less than 5-ps jitter. TTC-PON pushes the limits of the PON technology by exploiting cutting-edge custom protocols on top of the commercially available XG-PON optical modules. It can potentially reuse the current optical fiber infrastructure already installed in the experiments and allows for high flexibility in terms of partitioning, which can ease future upgrades of the TTC network. The system features a picosecond-level on-the-fly phase monitoring for each slave’s recovered clock by exploiting the bidirectionality of the network. In addition, a full set of link-quality monitoring tools was developed, allowing real-time performance monitoring. An overview of the tailored protocols will be given together with the details on the system implementation, operation, and performance. A discussion on the characterization campaign of more than 1000 optical modules delivered to the first implementation of the TTC-PON system will be drawn

Achieving Picosecond-Level Phase Stability in Timing Distribution Systems With Xilinx Ultrascale Transceivers

This article discusses the challenges posed on the field-programmable gate array (FPGA) transceivers in terms of phase-determinism requirements for timing distribution at the Large Hadron Collider (LHC) experiments. Having a fixed phase after startups is a major requirement, and the typical phase variations observed in the order of tens of picoseconds after startups while using the state-of-the-art design techniques are no longer sufficient. Each limitation observed in the transmitter and receiver paths of the high-speed transceivers embedded in the Xilinx Ultrascale FPGA family is further investigated and solutions are proposed. Tests in hardware using Xilinx FPGA evaluation boards are presented. In addition to a higher phase determinism, the techniques presented make it possible to fine-tune the skew of a link with a picosecond resolution, greatly simplifying clock-domain crossing inside the FPGAs and providing better short-term stability for the FPGA-recovered clock in a high-speed link

Comparison of the radiation hardness of silicon Mach-Zehnder modulators for different DC bias voltages

Radiation hard optical links are the backbone of read-out systems in high-energy physics experiments at CERN. The optical components have to withstand large doses of radiation and provide high data rates. Silicon photonics is currently being considered a promising technology to replace electrical and optical links in future experiments. It has already been demonstrated that integrated silicon Mach-Zehnder modulators can withstand a high neutron fluence and large total ionizing doses. Before read-out systems based on these components can be taken into consideration, it has to be determined how biasing affects their radiation hardness. For this reason we prepared bonded and fiber-pigtailed prototypes and irradiated them with x-rays. We found that under reverse-bias the radiation hardness of the tested components is reduced in comparison to un-biased samples. However, we were able to show that one device type can withstand the radiation without phase shift degradation up to 1 MGy despite the accelerated degradation due to biasing

Comparitive Aanalysis of the Results of Performance Strategies Tests Between British and Hungarian Female Gymnasts

The aim of the present study was to describe/explain differences in the psychological skills of the British (N=17) and Hungarian (N=16) female gymnasts. Members of both groups who had been preparing for the London Olympic Games were selected to participate in our study. The behavior strategy of female gymnasts was measured with the Test of Performance Strategies (TOPS) instrument. The questionnaire was applied to Hungarian and British participants. Test-retest reliability was between 0.61 and 0.89. Cronbach�s alpha values were between 0.74 and 0.93 during the practice period in Hungarian group. Test-retest values measured during the competition period were between 0.63 and 0.87, while the alpha values ranged from 0.73 to 0.88 also in Hungarian. Differences were hypothesized in the psychological skills between the two samples of gymnasts. The hypotheses were partially confirmed. Results suggest that gymnast groups attain their goals related to sport performance through different behavioral strategies

Demonstrating TTC-PON robustness and flexibility

In 2016, a TTC-PON (Timing, Trigger and Control system based on Passive Optical Networks) demonstrator was presented at TWEPP as an alternative to replace the TTC system, currently responsible for delivering timing, trigger and control commands in the LHC experiments. Towards a deployment foreseen for ALICE phase-1 upgrade, the system has been consolidated through flexible software implementation providing full configuration, complete calibration and extended monitoring and diagnostic tools. A new demonstrator setup was built with various FPGA platforms to test the system with an increased number of nodes and under different environmental conditions. This paper focuses on the TTC-PON system design with a discussion on its features and scaled-up tests