Trigger Rate Research Articles

Level-1 track finding with an all-FPGA system at CMS for the HL-LHC

The CMS experiment at the LHC is designed to study a wide range of high energy physics phenomena. It employs a large all-silicon tracker within a 3.8 T magnetic solenoid, which allows precise measurements of transverse momentum ( p T ) and vertex position. This tracking detector will be upgraded to coincide with the installation of the High-Luminosity LHC (HL-LHC), which will provide up to about 1 0 35 cm − 2 s − 1 to CMS, or up to 200 collisions per 25 ns bunch crossing. This new tracker must maintain the nominal physics performance in this more challenging environment. Novel tracking modules that utilize closely spaced silicon sensors to discriminate on track p T have been developed to allow the readout of only hits compatible with p T > 2-3 GeV tracks to off-detector trigger electronics. This would enable the use of tracking information to produce the Level-1 trigger of the experiment, a requirement to keep the Level-1 triggering rate below the 750 kHz target, while maintaining physics sensitivity. A concept for an all-FPGA based track finder using a fully time-multiplexed architecture is presented. Hardware demonstrators have been used to prove the feasibility and capability of such a system using two different reconstruction algorithms. The proposed scaling of the demonstrators to the final system is showed as well as the new technologies used in the first prototypes.

Market driven ship investment decision using the real option approach

This paper analyzes ship investment behavior where the main driving force is future freight earnings. The shipping market is cyclic and uncertain, and the decision is whether to invest ships now or later. Theoretically, we found the trigger rates—the necessary freight rates for profitable ship investment—for both the net present value (NPV) and real option approach (ROA), assuming that future freight earnings follow a mean reverting stochastic process. The combination of these trigger rates provides the necessary and sufficient conditions for immediate investment. Empirically, we estimated the trigger rates for the whole sample from January 1976 to July 2014, as well as sub-samples that take into account structural changes in the shipping market. Both theoretical and empirical results show that ship investment decisions can be made based on the relationships between the current freight rate and the trigger rates from NPV and ROA. If the freight rate cannot make NPV positive, no investment should be considered. Immediate investment is only recommended when the freight rate is higher than the trigger rate using ROA. Sensitivity analysis shows that the trigger rate is most sensitive to changes in the long-run mean of the freight rate. A simple regression analysis indicates that our model can explain market driven ship investment activities in the past. In addition, results that incorporate structural breaks in the shipping market are closer to actual investment behavior in the market.

Pulsed Reset Protocol for Fixed-Frequency Superconducting Qubits

The unconditional and fast reset of fixed-frequency superconducting qubits is crucial for the operation of near-term quantum computers at elevated trigger rates. Many reset schemes are either conditional (depend on the qubit's state) or require flux tunability. This study presents an all-microwave pulsed reset sequence that uses the readout resonator to unconditionally empty a fixed-frequency transmon qubit, and that also reduces the qubit thermal population. This method could be used to increase the repetition rate of a superconducting quantum computer running, for example, variational eigensolvers requiring many measurements.

ELM frequency enhancement and discharge modification through lithium granule injection into EAST H-modes

The injection of impurity granules into fusion research discharges can serve as a catalyst for ELM events. For sufficiently low ELM frequencies, and granule sizes above a threshold, this can result in full control of the ELM cycle, referred to as ELM pacing. For this research, we extend the investigation to conditions where the natural ELM frequency is too high for ELM pacing to be realized. Utilizing multiple sizes of lithium granules and classifying their effects by granule size, we demonstrate that ELM mitigation through frequency multiplication can be used at ELM triggering rates that nominally make ELM pacing unrealizable. We find that above a size threshold, injected granules promptly trigger ELMs and commensurately enhance the ELM frequency. Below this threshold size, injection of an individual granule does not always lead to the prompt triggering of an ELM; however, collective ablation in the edge pedestal region does enhance the ELM frequency. Specifically, Li granules too small to individually trigger ELMs were injected into EAST H-mode discharges at frequencies up to 2.3 kHz; collectively the granules were observed to enhance the natural ELM frequency up to 620 Hz, resulting in a ~2.4 × multiplication of the natural ELM frequency and a 50% decrease of the ELM size.

The new octal amplifier–shaper–discriminator chip for the ATLAS MDT chambers at HL-LHC

In order to fully exploit the physics potential of the ATLAS experiment at the HL-LHC, the trigger rate of and maximum latency of the first-level trigger system will be increased to 1 MHz and 10 μ s , respectively. In addition, a new first-level muon track trigger with high momentum resolution based on the ATLAS precision Muon Drift-Tube (MDT) chambers will be employed which requires triggerless readout. The TDC ASICs of the current front-end electronics of the MDT chambers are incompatible with these requirements. The front-end boards, each with a TDC chip and three 8-channel amplifier–shaper–discriminator (ASD) chips have to be replaced. Therefore, a new octal ASD2 ASIC has been developed in modern 130 nm IBM/Global Foundries CMOS technology. The chip also contains a Wilkinson ADC to perform both time-over-threshold and signal charge measurement. The ASD design has been fully qualified for the serial production of 80000 chips for ATLAS. The performance in terms of signal rise time and channel uniformity significantly surpasses the one of the previous chip while keeping the power consumption constant. In addition to the characterization with test pulses, several chips have been mounted on the front-end boards and tested in a muon beam at the Gamma Irradiation Facility GIF++ at CERN up to high counting rates where the superior drift time and spatial resolution becomes evident. • New Amplifier–Shaper–Discriminator chips for the readout of ATLAS (s)MDT chambers at HLLHC. • Design of new ASD chip in 130 nm CMOS IBM/Global Foundries technology completed. • Improved signal rise time and channel uniformity. • Radiation hardness far better than needed in the ATLAS muon spectrometer at HLLHC. • Successful full performance test in a muon beam at CERN under intense gamma irradiation.

Containability With Event-Based Sampling for Scalar Systems With Time-Varying Delay and Uncertainty

This letter studies unstable scalar continuous-time systems with uncertain parameters that are controlled over a network with finite capacity with possible uncertain, but uniformly bounded, time-varying transmission delays. While the decoder and controller are assumed to be static and memoryless, we are particularly interested in the role of the sampling mechanism that is allowed to be event-based, i.e., dependent on the state. The control goal is to guarantee containability and to characterize the minimal requirements in terms of asymptotic average bit and triggering rates for satisfying this objective. Our first investigation neglects the transmission delay and focuses on the importance of the alphabet due to uncertain system parameters. The remainder of the study characterizes the general case, by deriving general bounds on the allowable delay and the asymptotic average bit and triggering rates for two alphabets. This letter closes with a comparison of the derived bounds and conclusions that can be drawn regarding the choice of the alphabet.

Upgrade of the ATLAS muon system for the HL-LHC

Abstract The muon spectrometer of the ATLAS detector will be significantly upgraded during the Phase-II upgrade in Long Shutdown 3 in order to cope with the operational conditions at the High-Luminosity LHC in Run 4 and beyond. Most of the electronics for the Resistive Plate Chambers (RPC), Thin Gap Chambers (TGC), and Monitored Drift Tube (MDT) chambers will be replaced to make them compatible with the higher trigger rates and longer latencies necessary for the new level-0 trigger. The MDT chambers will be integrated into the level-0 trigger in order to sharpen the momentum threshold. Additional RPC chambers will be installed in the inner barrel layer to increase the acceptance and robustness of the trigger. Some of the MDT chambers in the inner barrel layer will be replaced with new small-diameter MDTs. New TGC triplet chambers in the barrel–endcap transition region will replace the current TGC doublets to suppress the high trigger rate from random coincidences in this region. The power system for the RPC, TGC, and MDT chambers and electronics will need to be replaced due to component obsolescence, aging, and radiation damage. A high- η tagger is under consideration to extend the angular acceptance for muon identification. The Phase-II upgrade concludes the process of adapting the muon spectrometer to the ever increasing performance of the LHC, which started with the Phase-I upgrade New Small Wheel project that will replace the Cathode Strip Chambers and the MDT chambers of the innermost endcap wheels by Micromegas and small-strip TGCs.

Tools for Trigger Rate Monitoring at CMS

In 2017, the LHC delivered an instantaneous luminosity of roughly 2.0 × 1034cm−2s−1 to the Compact Muon Solenoid (CMS) experiment, with about 60 simultaneous proton-proton collisions (<µ>) per event. In these challenging conditions, it is important to be able to intelligently monitor the rate at which data are being collected (the trigger rate). It is not enough to simply look at the trigger rate; it is equally important to compare the trigger rate with expectations. We present a set of software tools that have been developed to accomplish this. The tools include a real-time component - a script that monitors the rates of individual triggers during data-taking, and activates an alarm if rates deviate significantly from expectation. Fits are made to previously collected data and extrapolated to higher <µ>. The behavior of triggers as a function of <µ> is then monitored as data are collected - plots are automatically produced on an hourly basis and uploaded to a web area for inspection. This same set of tools can also be used offline in data certification, as well as in more complex offline analysis of trigger behavior.

The COSINE-100 data acquisition system

COSINE-100 is a dark matter direct detection experiment designed to test the annual modulation signal observed by the DAMA/LIBRA experiment. COSINE-100 consists of 8 NaI(Tl) crystals with a total mass of 106 kg, a 2200 L liquid scintillator veto, and 37 muon detector panels. We present details of the data acquisition system of COSINE-100, including waveform storage using flash analog-to-digital converters for crystal events and integrated charge storage using charge-sensitive analog-to-digital converters for liquid scintillator and plastic scintillator muon veto events. We also discuss several trigger conditions developed in order to distinguish signal events from photomultiplier noise events. The total trigger rate observed for the crystal/liquid scintillator (plastic scintillator) detector is 15 Hz (24 Hz).

A high angular resolution silicon microstrip telescope for crystal channeling studies

A charged particle telescope has been deployed for data taking at high rates in a CERN beam line using protons and other particles. The apparatus has a baseline of approximately 10 m in each arm, and achieves an angular resolution of 5.4 μrad using 400 GeV/c protons. The electronic readout and data acquisition system is based on that developed for the CMS Tracker, and provides almost deadtime-free operation at trigger rates of up to about 10 kHz.The telescope was developed to characterize crystals used in channeling experiments with a primary objective to validate them for use in a future LHC beam collimation system. The telescope has also been used for other studies of fundamental phenomena associated with the channeling process.The telescope is described, and its measured performance, referring to results from channeling studies, including recent measurements in heavy ion beams.

Trigger performance verification of the FlashCam prototype camera

FlashCam is a camera proposed for the medium-sized telescopes of the Cherenkov Telescope Array (CTA). We compare camera trigger rates obtained from measurements with the camera prototype in the laboratory and Monte-Carlo simulations, when scanning the parameter space of the fully-digital trigger logic and the intensity of a continuous light source mimicking the night sky background (NSB) during on-site operation. The comparisons of the measured data results to the Monte-Carlo simulations are used to verify the FlashCam trigger logic and the expected trigger performance.

Evaluation of low-flow metrics as environmental instream flow standards during long-term average and 2016 drought conditions: Tombigbee River Basin, Alabama and Mississippi, USA

Abstract Environmental instream flows are a common tool for maintaining river flows that are required to sustain both ecosystem and societal needs. Many of the most widely adopted environmental flow standards are based on historical flow, mainly because of the relative simplicity of these methods. Few previous studies, however, have examined the ability of historical flow standards to protect low flows. Here, the low-flow protective ability of five different historical flow methods, using 35 gaging stations in the Tombigbee River Basin of Alabama and Mississippi, was analyzed. The minimum environmental flow thresholds were calculated using the five indices, and the number of times in a recent 32-year period flows fell below each threshold was determined. The Tennant-based threshold was reached most frequently, followed by the modified Tennant. Although other low-flow metrics, such as 7Q10, were triggered infrequently (9% of the time) over the whole period, triggering rates increased to 46% for 7Q10 during the drought of 2016, suggesting that even minimal low-flow standards may provide some benefit during drought. Analyzing historical flow methods to see how often they would result in management actions if implemented is a useful way of developing guidance on the adoption of minimum environmental instream flow standards.

ATLAS Tile Calorimeter upgrades for HL-LHC

Abstract The High-Luminosity phase of the Large Hadron Collider (LHC) at CERN is expected to begin in 2026, delivering a luminosity of 5 × 1 0 34 cm − 2 s − 1 , with up to 200 interactions per 25 ns bunch crossing. In order to cope with the expected high trigger rates and intense radiation environment, the ATLAS Tile Calorimeter will be upgraded with re-designed electronic systems that will maintain its optimal performance in its future operation.

A New Design of Hardware Trojan Based on Path Delay

A new design method of hardware Trojan based path delay is proposed, the trigger of the Trojan is designed by using the meta-stability of flip-flop. Compared with the traditional hardware Trojan, the path delay Trojan can’t change the circuit function, and can effectively avoid the function equivalence detection, so it has a very high concealment. Inserted path delay Trojan in the AES (Advanced Encryption Standard) circuit, then successfully got the key with the frequency attack. After analyzed the leakage probability of key under different working frequency and different delay structure, obtained an effective method to control the trigger rate of path delay Trojan.

Level Zero Trigger Processor for the NA62 experiment

The NA62 experiment is designed to measure the ultra-rare decay K+ arrow π+ ν ν̄ branching ratio with a precision of ∼ 10% at the CERN Super Proton Synchrotron (SPS). The trigger system of NA62 consists in three different levels designed to select events of physics interest in a high beam rate environment. The L0 Trigger Processor (L0TP) is the lowest level system of the trigger chain. It is hardware implemented using programmable logic. The architecture of the NA62 L0TP system is a new approach compared to existing systems used in high-energy physics experiments. It is fully digital, based on a standard gigabit Ethernet communication between detectors and the L0TP Board. The L0TP Board is a commercial development board, mounting a programmable logic device (FPGA). The primitives generated by sub-detectors are sent asynchronously using the UDP protocol to the L0TP during the entire beam spill period. The L0TP realigns in time the primitives coming from seven different sources and performs a data selection based on the characteristics of the event such as energy, multiplicity and topology of hits in the sub-detectors. It guarantees a maximum latency of 1 ms. The maximum input rate is about 10 MHz for each sub-detector, while the design maximum output trigger rate is 1 MHz. A description of the trigger algorithm is presented here.

Thermal mock-up studies of the Belle II vertex detector

The ongoing upgrade of the asymmetric electron–positron collider SuperKEKB at the KEK laboratory, Japan aims at a 40-fold increase of the peak luminosity to 8 × 1035 cm−2s−1. At the same time the complex Belle II detector is being significantly upgraded to be able to cope with the higher background level and trigger rates and to improve overall performance. The goal of the experiment is to explore physics beyond the standard model with a target integrated luminosity of 50 ab−1 in the next decade. The new vertex detector (VXD), comprising two layers of DEPFET pixel detectors (PXD) surrounded by 4 layers of double sided silicon strip detectors (SVD), is indispensable for vertex determination as well as for reconstruction of low momentum tracks that do not reach the central drift chamber (CDC). Within the confined VXD volume the front-end electronics of the two detectors will dissipate about 1 kW of heat. The VXD cooling system has been designed to remove this heat with the constraint to minimize extra dead material in the physics acceptance region. Taking into account additional heat intake from the environment the cooling system must have a cooling capacity of 2–3 kW. To achieve this goal evaporative two-phase CO2 cooling in combination with forced N2 flow is used in the VXD cooling system. In order to verify and optimize the cooling concept and to demonstrate that acceptable operation conditions for the VXD system as well as the surrounding CDC can be obtained, a full size VXD thermal mock-up has been built at DESY. Various thermal and mechanical tests carried out with this mock-up are reported.

An optical fiber-based flexible readout system for micro-pattern gas detectors

This paper presents an optical fiber-based readout system that is intended to provide a general purpose multi-channel readout solution for various Micro-Pattern Gas Detectors (MPGDs). The proposed readout system is composed of several front-end cards (FECs) and a data collection module (DCM). The FEC exploits the capability of an existing 64-channel generic TPC readout ASIC chip, named AGET, to implement 256 channels readout. AGET offers FEC a large flexibility in gain range (4 options from 120 fC to 10 pC), peaking time (16 options from 50 ns to 1 us) and sampling freqency (100 MHz max.). The DCM contains multiple 1 Gbps optical fiber serial link interfaces that allow the system scaling up to 1536 channels with 6 FECs and 1 DCM. Further scaling up is possible through cascading of multiple DCMs, by configuring one DCM as a master while other DCMs in slave mode. This design offers a rapid readout solution for different application senario. Tests indicate that the nonlinearity of each channel is less than 1%, and the equivalent input noise charge is typically around 0.7 fC in RMS (root mean square), with a noise slope of about 0.01 fC/pF. The system level trigger rate limit is about 700 Hz in all channel readout mode. When in hit channel readout mode, supposing that typically 10 percent of channels are fired, trigger rate can go up to about 7 kHz. This system has been tested with Micromegas detector and GEM detector, confirming its capability in MPGD readout. Details of hardware and FPGA firmware design, as well as system performances, are described in the paper.

An image-based array trigger for imaging atmospheric Cherenkov telescope arrays

It is anticipated that forthcoming, next generation, atmospheric Cherenkov telescope arrays will include a number of medium-sized telescopes that are constructed using a dual-mirror Schwarzschild–Couder configuration. These telescopes will sample a wide (8°) field of view using a densely pixelated camera comprising over 104 individual readout channels. A readout frequency congruent with the expected single-telescope trigger rates would result in substantial data rates. To ameliorate these data rates, a novel, hardware-level Distributed Intelligent Array Trigger (DIAT) is envisioned. A copy of the DIAT operates autonomously at each telescope and uses reduced resolution imaging data from a limited subset of nearby telescopes to veto events prior to camera readout and any subsequent network transmission of camera data that is required for centralized storage or aggregation. We present the results of Monte-Carlo simulations that evaluate the efficacy of a “Parallax width” discriminator that can be used by the DIAT to efficiently distinguish between genuine gamma-ray initiated events and unwanted background events that are initiated by hadronic cosmic rays.

Optimal design of waveform digitisers for both energy resolution and pulse shape discrimination

Fast digitisers and digital pulse processing have been widely used for spectral application and pulse shape discrimination (PSD) owing to their advantages in terms of compactness, higher trigger rates, offline analysis, etc. Meanwhile, the noise of readout electronics is usually trivial for organic, plastic, or liquid scintillator with PSD ability because of their poor intrinsic energy resolution. However, LaBr3(Ce) has been widely used for its excellent energy resolution and has been proven to have PSD ability for alpha/gamma particles. Therefore, designing a digital acquisition system for such scintillators as LaBr3(Ce) with both optimal energy resolution and promising PSD ability is worthwhile. Several experimental research studies about the choice of digitiser properties for liquid scintillators have already been conducted in terms of the sampling rate and vertical resolution. Quantitative analysis on the influence of waveform digitisers, that is, fast amplifier (optional), sampling rates, and vertical resolution, on both applications is still lacking. The present paper provides quantitative analysis of these factors and, hence, general rules about the optimal design of digitisers for both energy resolution and PSD application according to the noise analysis of time-variant gated charge integration.

The TOTEM DAQ based on the Scalable Readout System (SRS)

The TOTEM (TOTal cross section, Elastic scattering and diffraction dissociation Measurement at the LHC) experiment at LHC, has been designed to measure the total proton-proton cross-section and study the elastic and diffractive scattering at the LHC energies. In order to cope with the increased machine luminosity and the higher statistic required by the extension of the TOTEM physics program, approved for the LHC’s Run Two phase, the previous VME based data acquisition system has been replaced with a new one based on the Scalable Readout System. The system features an aggregated data throughput of 2GB / s towards the online storage system. This makes it possible to sustain a maximum trigger rate of ∼ 24kHz, to be compared with the 1KHz rate of the previous system. The trigger rate is further improved by implementing zero-suppression and second-level hardware algorithms in the Scalable Readout System. The new system fulfils the requirements for an increased efficiency, providing higher bandwidth, and increasing the purity of the data recorded. Moreover full compatibility has been guaranteed with the legacy front-end hardware, as well as with the DAQ interface of the CMS experiment and with the LHC’s Timing, Trigger and Control distribution system. In this contribution we describe in detail the architecture of full system and its performance measured during the commissioning phase at the LHC Interaction Point.