Advancements on AIDA-2020: from software, data acquisition and microelectronics to cryogenics, gas detectors and calorimeters
Catarina Serafim, Daniela Antonio (CERN), 28/04/2020
The Compact Muon Solenoid (CMS) is a general-purpose detector at the Large Hadron Collider (LHC). It has a broad physics programme ranging from studying the Standard Model (including the Higgs boson) to searching for extra dimensions and particles that could make up dark matter (Image: CERN).
When particles are made to collide in a particle accelerator, their interactions with the detector’s systems create an enormous flow of data that must be processed so that the particles can be identified; complex data-acquisition and computing systems are used to analyse vast amounts of collision events and to store and process the resulting data. Upgrades of the different detecting systems allow for a more precise identification of the particles generated in the collision, which in turn results in even more data. Great research efforts have been made in every work package to improve the performance of a detector in both these areas, from software, data acquisition and microelectronics to cryogenics, gas detectors and calorimeters.
“Many advancements have been made in fields of detector science and for applications in and beyond particle physics, which future projects will build on,” says Felix Sefkow, project coordinator of AIDA-2020 and leader of the Project Preparation Team for the new H2020 Innovation Pilot Call for detector technologies at accelerators. “As detectors are complex systems, bringing the community together ensures that all developments complement each other for the greater benefits from latest technologies.”
These are some of the community’s main achievements in the context of AIDA-2020.
Developing and improving computing software
The researchers and developers for advanced software within AIDA-2020 have addressed the core simulation and reconstruction software for high-energy physics. Developments in this area include the new release of the VecGeom geometry modeller library, which contains almost the full set of geometrical representations used by the set-ups at the LHC. VecGeom can be used directly with Geant4, ROOT and GeantV as a Unified Solids package for parallelised computing architectures.
In addition, a sophisticated pattern recognition software, originally developed for highly granular calorimeters, was successfully used in the reconstruction of neutrino interactions in a Liquid Argon detector and cosmic-ray muons in many different analyses. The development of PODIO - an event data model toolkit for the efficient creation of Event Data Models in C++ with high performance I/O – and the development of DDG4 that allows users of DD4hep to simulate the physics response of their detector with minimal effort was also achieved.
The project also saw the implementation of the additional packages DDCond and DDAlign, supporting detector conditions and alignment constants in the framework of the DD4hep toolkit. DD4hep is being prepared for usage in the LHCb experiment, with the modification of the LHCb alignment software currently ongoing.
Data acquisition systems for beam tests
The Common DAQ helped tie together the work of different teams working on detector development, and a new Trigger/Timing Logic Unit (TLU) has been designed and prototype. The AIDA-2020 TLU is a piece of hardware that distributes signals to the detectors participating in a beam test. These signals allow the data from the different detectors corresponding to the same particle to be combined.
Moreover, two software codes, EUDAQ2 and DQM4HEP, have been released and will be used in future beam tests for other linear collider detectors; it is available for other systems as well.
EUDAQ2 allows for different levels of integration, such as run control, timing/synchronisation hardware, and data collection. The software was released as the basic software framework used in beam tests with multiple linear-collider detectors. With the move from EUDAQ1 to EUDAQ2, it is now possible to collect data on multiple PCs rather than having a single data collector. The DQM4HEP framework provides a reliable method for online monitoring and data-quality monitoring for physics test beam data that is generic, flexible and scalable. It has proven that it can adapt to different detector types, including those with different event and readout structures.
Microelectronics
On the microelectronics and interconnections sector, a large-scale demonstrator chip, called RD53A, was developed within the CERN-based RD53 collaboration. The ultimate goal of the RD53A is to evaluate the attainable performance with the 65-nm CMOS– Complementary Metal-Oxide Semiconductor – technology in view of its application on the readout of pixel sensors at the high-luminosity LHC.
In addition, the feasibility of Through-Silicon Vias (TSV) in the 100-nm-scale CMOS integrated circuits was demonstrated and provides confirmation that this promising technology can be applied to the next generation of pixel-readout circuits in 65-nm CMOS. TSV are a key ingredient for the 3D integration process between silicon pixel sensors and CMOS readout integrated circuits.
In the context of AIDA-2020, a better understanding of novel High-Voltage and Resistive (HV/HR) CMOS Sensors for high-energy physics (and other applications) was also achieved through various circles of design, simulation, fabrication and testing. Technical solutions were developed for the hybridisation procedure for AC-coupled and DC-coupled devices, which led to a more robust and reliable process.
Advanced Hybrid Pixel Detectors
Thin planar silicon sensors with active edge and various guard-ring layouts have been investigated, using two-dimensional finite-element TCAD simulations. TCAD – Technology Computer-Aided Design – tools have been used to optimise the design of planar pixel cells, compatible with the new readout chips in 65-nm CMOS technology. TCAD simulation tools have also been used to understand the details of the Low-Gain Avalanche Detectors (LGAD) electric field configurations, and to define the doping profile for the LGAD production to tune the avalanche mechanism. The LGAD technology offers superior performance for fast timing applications in irradiated environments.
Cryogenics
Developments on innovative purification and monitoring contributed to the construction of different temperature monitoring devices, level controls, cameras, and for the investigation of purification and cryogenics, to be used in the next generation of large underground Liquid Argon detectors for physics with neutrino beams. Great developments were made on testing, coating and deployment techniques for photo-detection systems based on cryogenic photomultipliers, as well as on charge readout systems and very high voltage.
Microchannel cooling
The research in microchannel cooling brought together several pioneering groups to join forces in the development of microchannel cooling in silicon detectors in high-energy physics. The work led to the production of prototype cooling structures of several designs and the development of solutions for the connectivity of microchannel cooling circuits. The production and characterisation of small-scale structures has also provided a strong impulse to the deployment of novel microchannel cooling techniques in high-energy physics experiments.
Innovative gas detectors
Innovative gas detectors present excellent options for efficient large tracking systems for high-energy physics detectors. Such structures use production technologies that are under continuous development, leading to a steady improvement in the detector quality.
With the new high-energy accelerators and their higher particle rates, it is necessary to upgrade the current RPC – Resistive Plate Chamber – detector technology. Developments were made to support the new requirements, so that the new RPC detectors have a higher rate capability, better space and time resolution, low noise and occupancy, and are supported by a faster and more sensitive electronics.
Developments were also made in the high-voltage power supply for micro-pattern gaseous detectors (MPGD), as well as establishing new MPGD structures with unprecedented performance, including a compact, spark-protected single amplification stage, suitable for a broad range of high-energy physics applications requiring operation in harsh environments.
Infrastructures for advanced calorimeters
AIDA-2020 saw the development and construction of test infrastructures for calorimeter elements to support the R&D activities in the area of calorimetry for future collider detectors. Development of tools and techniques for more compact and strongly segmented designs were made to allow more precise energy measurements of single particle and jets, the three-dimensional reconstruction of the hadronic shower, and the identification of individual particle tracks. These compact designs are possible with the development of microelectronics embedded in the detector volume. Numerous technical challenges have been addressed, such as low-power readout electronics placed very close to the sensors in a confined environment, and the design of maximum compactness to avoid dead spaces and to permit the best possible particle separation.