Particle Physics Experiments Research Articles

Beam dynamics driven design of powerful energy recovery linac for experiments

Powerful ERL for experiments (PERLE) is a novel energy recovery linac (ERL) test facility [1], designed to validate choices for a 50 GeV ERL foreseen in the design of the Large Hadron Electron Collider and the Future Circular Collider and to host dedicated nuclear and particle physics experiments. Its main goal is to demonstrate the high current, continuous wave, multipass operation with superconducting cavities at 802 MHz. With very high beam power (10 MW), PERLE offers an opportunity for controllable study of every beam dynamic effect of interest in the next generation of ERLs and becomes a “stepping stone” between the present state-of-the-art 1 MW ERLs and the future 100 MW scale applications. Published by the American Physical Society 2024

Breakdown performance of guard ring designs for pixel detectors in 150 nm CMOS technology

Silicon pixel sensors manufactured using commercial CMOS processes are promising instruments for high-energy particle physics experiments due to their high yield and proven radiation hardness. As one of the essential factors for the operation of detectors, the breakdown performance of pixel sensors constitutes the upper limit of the operating voltage. Six types of passive CMOS test structures were fabricated on high-resistivity wafers. Each of them features a combination of different inter-pixel designs and sets of floating guard rings, which differ from each other in the geometrical layout, implantation type, and overhang structure. A comparative study based on leakage current measurements in the sensor substrate of unirradiated samples was carried out to identify correlations between guard ring designs and breakdown voltages. TCAD simulations using the design parameters of the test structures were performed to discuss the observations and, together with the measurements, ultimately provide design features targeting higher breakdown voltages.

Real-Time Graph Building on FPGAs for Machine Learning Trigger Applications in Particle Physics

We present a design methodology that enables the semi-automatic generation of a hardware-accelerated graph building architectures for locally constrained graphs based on formally described detector definitions. In addition, we define a similarity measure in order to compare our locally constrained graph building approaches with commonly used k-nearest neighbour building approaches. To demonstrate the feasibility of our solution for particle physics applications, we implemented a real-time graph building approach in a case study for the Belle II central drift chamber using Field-Programmable Gate Arrays (FPGAs). Our presented solution adheres to all throughput and latency constraints currently present in the hardware-based trigger of the Belle II experiment. We achieve constant time complexity at the expense of linear space complexity and thus prove that our automated methodology generates online graph building designs suitable for a wide range of particle physics applications. By enabling an hardware-accelerated preprocessing of graphs, we enable the deployment of novel Graph Neural Networks (GNNs) in first-level triggers of particle physics experiments.

PyPWA: A software toolkit for parameter optimization and amplitude analysis

PyPWA is a toolkit designed to optimize parametric models describing data and generate simulated distributions according to a model. Its software has been written within the python ecosystem with the goal of performing Amplitude or Partial Wave Analysis (PWA) in nuclear and particle physics experiments. We briefly describe the general features of amplitude analysis and we provide a description of the PyPWA software design and usage. We also provide benchmarks of the scaling and an example of its application.

Cryogenic acoustic microscopy and evaulation of electronic components

Electronics operating at cryogenic temperatures are essential in fields like space exploration and particle physics. The Deep Underground Neutrino Experiment (DUNE), a next generation particle physics experiment, will rely on tens of thousands of custom designed application specific integrated circuits (ASICs) operating directly in liquid argon (87 K) for decades without repair or replacement. Ensuring circuit functional reliability throughout the duration of the experiment is mission critical. Both functional and nondestructive testing are employed to safeguard circuit quality and reliability. Part of this work involves the design, testing, and data analysis of a cryogenic acoustic microscope (CryoSAM) operating at 15 MHz. The CryoSAM is capable of interrogating ASICs at both room temperature (300 K) and in liquid nitrogen (77 K), identifying acoustic anomalies likely arising from thermal stress and manufacturing-related defects, using a powerful correlation analysis technique. These anomalies can lead to functional degradation and suboptimal electronic performance of the circuit sensors. Image analysis and correlations are used to compare differences seen before and after cryogenic temperature cycling. Data are reported that were collected at both room temperature and when cooled using liquid nitrogen. Designs and challenges of operating the instrument at cryogenic temperatures are also discussed.

Design of a high-precision clock distribution and synchronization system

In large-scale nuclear and particle physics experiments, there is a high demand for high precision clock distribution and synchronization. In this paper, the design and testing of a high precision clock distribution and synchronization system for the CSR External Target Experiment (CEE) is presented. To achieve high synchronization precision, a dedicated high-quality clock distribution network is designed, while the timestamp synchronization is achieved over the existing trigger link in CEE with a customized protocol in order to simplify the system structure. Automatic metastability elimination and real-time monitoring of both the timestamps on the front end nodes and the clock electronics status are also implemented. The test results indicate that the period jitter of the clock network is better than 4 ps rms, and all the expected functionalities have been achieved successfully.

High power electrostatic beam splitter for a proton beamline

The High Intensity Proton Accelerator facility (HIPA) delivers a 590 MeV cw (50.6 MHz) proton beam with up to 1.4 MW beam power (2.4 mA) to spallation and meson production targets serving particle physics experiments and material research. The main accelerator is the ring cyclotron, an isochronous proton machine accelerating an injected 72 MeV beam to a final 590 MeV. A few meters downstream of the ring cyclotron, an electrostatic beam splitter was installed in the 1980s and originally designed to peel off from a 200 μA beam up to 20 μA (12 kW beam power). Future initiatives will also make use of the splitter. Specifically, as part of the Isotope and Muon Production using Advanced Cyclotron and Target technologies (IMPACT) upgrade project, Targeted Alpha Tumour Therapy and Other Oncological Solutions (TATTOOS), an online isotope separation facility will allow to produce promising radionuclides for diagnosis and therapy of cancer in quantities sufficient for clinical studies. The TATTOOS facility includes a dedicated beamline intended to operate at a beam intensity of 100 μA (60 kW beam power), requiring continuous splitting of the high-power main beam via the splitter. As a step forward toward reaching the desired beam intensity, a beam study was carried out to test the viability of the existing splitter for TATTOOS. The results of this study show that a record of 90 μA (53 kW beam power) was peeled off a horizontally and vertically enlarged beam by the splitter. The successful beam strategy employed during the study as well as the results of several key measurements are presented in this paper, with particular emphasis on diagnostic measurements. Additionally, to support the measurements, a computational model of the splitter has been implemented using Monte Carlo simulation tools, including realistic geometry, electrostatic fields, beam optics, and power deposition calculations. Overall, the results of this paper show that through the combination of beam measurements and simulations, the existing splitter can be used to reach the 100−μA beam intensity requirement for TATTOOS. Published by the American Physical Society 2024

Numerical analysis of a steady-state and transient performance using a tube-in-tube heat exchanger unit for cryogenic process simulator

Large scale Helium Refrigerators and Liquefiers (HRLs) are essential technologies in particle physics experiments and the nuclear energy sector. Most HRLs employ a modified version of the Collin's cycle, which involves a room temperature compressor, several counter-flow heat exchangers (HXs), expanders, and a J-T valve to produce liquid helium. The performance of HRLs is mainly governed by the efficacy of HXs and requires accurate process modeling and simulation. Although various platforms for process modeling and simulation of HXs are available, both commercial and open source, significant customization is required to use them in the cryogenic domain. Moreover, the transient simulation of a HX in two-phase has always been a concern. Therefore, there is a need to develop a numerical model of a HX to meet the requirements of the cryogenic domain specially in two-phase region.In present study, a HX is being modeled on the open source platform Python®. The developed numerical model is based on the distributed parameter approach to capture the impact of the variable fluid properties as well as their impact on the heat transfer coefficient. The model allows user to choose a suitable heat transfer correlation as per the requirement in different regime of the phases across the length of HX. The developed model may be suitable to simulate the HXs used as LN2 precooling, HXs of helium plant operating in mixed mode, and J-T heat exchangers where fluids undergoes phase changes along the flow length.The created models are initially tested against their design data, and results are then acquired under non-standard operating conditions. The outcomes are validated with experimental data from the ITER-India cryogenic Laboratory (IICL) after being first verified using the commercial process simulator Aspen HYSYS®.

Novel developments on the OpenIPMC project

We present the recent developments in the context of the OpenIPMC project, which proposes a free and open-source Intelligent Platform Management Controller (IPMC) software and an associated controller mezzanine card for use in ATCA electronic boards. We discuss our experience in the operation of OpenIPMC on prototype boards designed for the upgrades of particle physics experiments at CERN and we show the addition of new features and support for new protocols in the firmware of the controller mezzanine card.

The k4Clue package: Empowering future collider experiments with the CLUE algorithm

High granularity calorimeters have become increasingly crucial in modern particle physics experiments, and their importance is set to grow even further in the future. The CLUstering of Energy (CLUE) algorithm has shown excellent performance in clustering calorimeter hits in the High Granularity Calorimeter (HGCAL) developed for the Phase-2 upgrade of the CMS experiment. In this paper, the suitability of the CLUE algorithm for future collider experiments has been investigated and its capabilities tested outside the HGCAL reconstruction software. To this end, a new package, k4Clue, was developed which is now fully integrated into the Gaudi software framework and supports the EDM4hep data format for inputs and outputs. The performance of CLUE was demonstrated in three detectors for future colliders: CLICdet for the CLIC accelerator, CLD for the FCC-ee collider and a second calorimeter based on Noble Liquid technology also proposed for FCC-ee. Excellent reconstruction performance was observed for single photon events, even in the presence of noise, and the results are compatible with the performance of the algorithms used currently as the baseline for shower reconstruction in future e+e−-colliders. Moreover, CLUE demonstrates impressive timing capabilities, outperforming the current baseline algorithms and this advantage remains consistent regardless of the number of input hits. This work highlights the adaptability and versatility of the CLUE algorithm for a wide range of experiments and detectors and the algorithm’s potential for future high-energy physics experiments beyond CMS.

Geant4 silver anniversary: 25 years enabling scientific production

This paper summarizes Geant4 contribution to scientific research overthe past 25 years through a scientometric analysis of the results with which it has beenassociated. The scientometric data collected from scholarly literature anddatabases are evaluated with methods pertaining to econometrics and ecology toquantify relevant traits, diversity and disparity in their scientific andgeographic distributions, and to identify statistically significant trends. Theanalysis reviews the contribution of Geant4 to the field — experimental particlephysics — that originally motivated its development and highlights its role inother research domains including nuclear physics and engineering, astrophysicsand space science, biomedical physics, archaeology and the cultural heritage.

A custom discrete amplifier-shaper-discriminator circuit for the drift chambers of the R3B experiment at GSI

This contribution presents a pragmatic approach to read-out electronics for drift chambers used in particle physics experiments, specifically for the R3B experiment at GSI. The design uses discrete miniature SMD components and LVDS inputs of a low-cost FPGA to achieve a performance similar to classic ASIC solutions to the problem. The circuit comprises a high gain, low noise amplifier, a custom signal shaper, tailored to the specifics of proportional counter signals, and a leading-edge discriminator with programmable threshold. The presented approach offers an attractive solution for small to medium sized detector systems that require specialized read-out electronics but cannot afford the high cost and development effort associated with ASICs.

Ultra-low background germanium assay at the Boulby Underground Laboratory

As we move to an era where next generation ultra-low background particle physics experiments begin to be designed and constructed, the ability to assay materials with high sensitivity and at speed with a variety of techniques will be key. This paper describes the Mirion Technologies (Canberra) specialty ultra-low background detectors installed and commissioned at the Boulby Underground Laboratory between 2017 and 2021. The low background levels of the detectors combine with low background shielding and a radon-reduced dry nitrogen purge system to give sensitivity approaching the best in the world without the need for intricate shielding solutions. For an optimised sample geometry, run for 100 d, it would be possible to reach close to 10 μBq kg-1 (10-12 g/g) for background radionuclides of interest in neutrinoless double-beta decay.

Ranking-based neural network for ambiguity resolution in ACTS

The reconstruction of particle trajectories is a key challenge of particle physics experiments, as it directly impacts particle identification and physics performances while also representing one of the main CPU consumers of many high-energy physics experiments. As the luminosity of particle colliders increases, this reconstruction will become more challenging and resourceintensive. New algorithms are thus needed to address these challenges efficiently. One potential step of track reconstruction is ambiguity resolution. In this step, performed at the end of the tracking chain, we select which tracks candidates should be kept and which must be discarded. The speed of this algorithm is directly driven by the number of track candidates, which can be reduced at the cost of some physics performance. Since this problem is fundamentally an issue of comparison and classification, we propose to use a machine learning-based approach to the Ambiguity Resolution. Using a shared-hits-based clustering algorithm, we can efficiently determine which candidates belong to the same truth particle. Afterwards, we can apply a Neural Network (NN) to compare those tracks and decide which ones are duplicates and which ones should be kept. This approach is implemented within A Common Tracking Software (ACTS) framework and tested on the Open Data Detector (ODD), a realistic virtual detector similar to a future ATLAS one. This new approach was shown to be 15 times faster than the default ACTS algorithm while removing 32 times more duplicates down to less than one duplicated track per event.

Triggerless data acquisition pipeline for Machine Learning based statistical anomaly detection

This work describes an online processing pipeline designed to identify anomalies in a continuous stream of data collected without external triggers from a particle detector. The processing pipeline begins with a local reconstruction algorithm, employing neural networks on an FPGA as its first stage. Subsequent data preparation and anomaly detection stages are accelerated using GPGPUs. As a practical demonstration of anomaly detection, we have developed a data quality monitoring application using a cosmic muon detector. Its primary objective is to detect deviations from the expected operational conditions of the detector. This serves as a proof-of-concept for a system that can be adapted for use in large particle physics experiments, enabling anomaly detection on datasets with reduced bias.

Building a Flexible and Resource-Light Monitoring Platform for a WLCG-Tier2

Software development projects at Edinburgh identified a desire to build and manage our own monitoring platform. This better allows us to support the developing and varied physics and computing interests of our Experimental Particle Physics group. This production platform enables oversight of international experimental data management, local software development projects and active monitoring of lab facilities within our research group. Larger sites such as CERN have access to many resources to support generalpurpose centralised monitoring solutions such as MONIT. At a WLCG Tier2 we only have access to a fraction of these resources and manpower. Recycling nodes from grid storage and borrowed capacity from our Tier2 Hypervisors has enabled us to build a reliable monitoring infrastructure. This also contributes back to our Tier2 management improving our operational and security monitoring. Shared experiences from larger sites gave us a head-start in building our own service monitoring (FluentD) and multi-protocol (AMQP/STOMP/UDP datagram) messaging frameworks atop both our Elasticsearch and OpenSearch clusters. This has been built with minimal hardware and software complexity, maximising maintainability, and reducing manpower costs. A secondary design goal has also been the ability to migrate and upgrade individual components with minimal service interruption. To achieve this, we made heavy use of different layers of containerisation (Podman/Docker), virtualization and NGINX web proxies. This presentation details our experiences in developing this platform from scratch with a focus on minimal resource use. This includes lessons learnt in deploying and comparing both an Elasticsearch and OpenSearch clusters, as well as designing various levels of automation and resiliency for our monitoring framework. This has culminated in us effectively indexing, parsing and storing >200GB of logging and monitoring data per day.

Design of a multidimensional data collection system based on DRS4 scheme

A high-speed data acquisition system based on DRS4 waveform digitization is designed to meet the requirements of high sampling rate, multi-parameter measurements, and long-distance transmission in some particle physics experiments. The system consists of a waveform digitization front-end board, a high-speed data transmission board, and an upper computer software. Test results show that the system has a high data transmission rate and a low BER and that the collected data can reconstruct and restore the input signal waveform well. In addition, we have analyzed the single-electrode dual-mode sensor, excitation signal generation module, resistor/capacitor conversion circuit, and phase-sensitive demodulation unit in the system. The experiments show that the system is stable in operation, flexible in use, and can significantly extend the measurement range.

Future physics prospects with CEPC and HL-LHC synergy

After constructing the Circular Electron Positron Collider (CEPC) and the High-Luminosity Large Hadron Collider (HL-LHC), particle physics experiments will reach a new mass region with more incredible energy. Both types of colliders have the unique duty of searching for new particles or estimating the coupling constants of the reactions based on their different structures, providing a different focus. This presentation will discuss and cover the regions of CEPC and HL-LHC to show their complementary functions. The CEPC can answer the Higgs particle, whether it is a composite particle, how it contributes to the dark matter mass, and whether its field provides enough matter mass for the universe. It can generally provide detections below 10 TeV, leading to possible new theories. For the HL-LHC, the upgraded HL-LHC has a higher luminosity and data acquisition capability, ten times higher than predicted. It is expected to produce 15 million Higgs particles annually, five times more than the LHC. The large number of collision events provides more opportunities to measure the characteristics of the Higgs particles.

TRANSLATE - a Monte Carlo simulation of electron transport in liquid argon

The microphysics of electron and photon propagation in liquid argon is a key component of detector design and calibrations needed to construct and perform measurements within a wide range of particle physics experiments. As experiments grow in scale and complexity, and as the precision of their intended measurements increases, the development of tools to investigate important microphysics effects impacting such detectors becomes necessary. In this paper we present a new time-domain Monte Carlo simulation of electron transport in liquid argon. The simulation models the TRANSport in Liquid Argon of near-Thermal Electrons (TRANSLATE) with the aim of providing a multi-purpose software package for the study and optimization of detector environments, with a particular focus on ongoing and next generation liquid argon neutrino experiments utilizing the time projection chamber technology. TRANSLATE builds on previous work of Wojcik and Tachiya, amongst others, introducing additional processes, including ionization, thus modeling the full range of drift electron scattering interactions. The simulation is validated by benchmarking its performance with swarm parameters from data collected in experimental setups operating in gas and liquid. Program summaryProgram Title:TRANSLATECPC Library link to program files:https://doi.org/10.17632/v3tr6xp53h.1Developer's repository link:https://github.com/davidc1/TRANSLATELicensing provisions: GNU General Public License 3.0Programming language: C▪, pythonExternal routines/libraries used: make, cmake (required), ipython notebook (optional)Nature of problem: Simulation of electron-argon scattering events at energies of 10−3−103 eVSolution method: Monte Carlo time-domain transport of electrons simulating momentum transfer, excitations, and ionization interaction modes utilizing input single and double-differential cross sections.Additional comments including restrictions and unusual features: Effects of ion space-charge or recombination with positive argon ions are not included.

Radioassay facilities at the STFC Boulby Underground Laboratory

For future low-background particle physics experiments, it will be essential to assay candidate detector materials using an array of assay techniques. To minimise the risk of sample contamination whilst moving between assay techniques, it is also sensible to minimise the distance between assay stations, particularly for non-destructive techniques where the sample may end up being installed into an experiment. The Boulby UnderGround Screening (BUGS) Facility comprises an array of germanium detectors, two XIA UltraLo-1800 surface-alpha counters, two radon emanation detectors and an Agilent ICP-MS system. This article describes each of these systems.