Research Infrastructures have a profound impact on research excellence, organisation of research and structuring of Physical Sciences and Engineering communities. RIs are scientific and technological hubs, which fully engage scientists to create, design, and exploit facilities to advance science, industrial innovation and manufacturing, with overall benefit to society.

The successful European RI landscape is the result of a long-term coordinated strategy to pool efforts and resources through international collaborations with inclusive, open, and excellence-based access policies. PSE RIs enable innovative research and technology development at a European and global scale, with a solid coverage of Astronomy & Astroparticle Physics (A&AP), Particle & Nuclear Physics (P&NP), and Analytical Physics (AP), and a growing systematic impact in new areas. PSE RIs are core research centres for producing excellent science culminating in several Nobel prizes for Physics and Chemistry. The common practice of RIs towards global cooperation enables even greater exchange of knowledge, skills and scientific advances. This way they can very efficiently address and solve scientific challenges, often combining multiple simultaneous probes and messengers within a complementary methods approach.

RIs have demonstrated their instrumental role to scientific communities and society during the COVID-19 pandemic, providing technologies, services and analytical skills, routinely available to PSE researchers, to support a prompt and well-coordinated response to a complex emergency. RIs have responded rapidly to new challenges, drawing on their strengths as science pillars, knowledge hubs and providers of reliable open data. Analytical facilities such as synchrotrons, neutron sources, lasers and electron microscopes were agile to rapidly establish access procedures for experiments on the structure and functioning of the virus. The COVID emergency accelerated the broader trend in the ability of RI to deploy their competences and capacities to address urgent societal issues, including the five Missions identified for Horizon Europe. Continued fostering of scientific and technological innovations is essential to develop the RIs and their co-operation beyond the state-of-the-art. It is also critical to create strategies for outreach to increase public awareness of the crucial role of RIs in helping Europe to reach the goals of these missions.

THE PSE LANDSCAPE AND ITS EVOLUTION PSE RIs enable understanding the physical structure of nature and its interactions over an enormous range of distances, energy and time, from the Big Bang to now, and from subnuclear scales to the whole observable Universe.

The landscape contains a variety of RIs in terms of advanced technologies and services for research and innovation. In ASTRONOMY & ASTROPARTICLE PHYSICS, data-sharing methods are extremely advanced and the remotely collected observational data represent an invaluable asset that can be accessed worldwide for research and educational scopes. In PARTICLE & NUCLEAR PHYSICS the exploitation of colliders and accelerators is organized under the umbrella of large international collaborations with researchers physically accessing the facilities to perform the experiments. For ANALYTICAL PHYSICS, the successful model of synchrotrons gives access to a very large number of diverse users moving to the facilities to carry out approved-for-access research. Integration of large-scale analytical facilities with complementary material synthesis, characterization and numerical simulation services facilitates the close engagement with researchers across universities, institutes and industry.

An overview of the RIs currently forming the European landscape is shown Figure 1. This is an updated version of the last Roadmap data on RIs based in Europe or participated by European countries, running international open access programmes for users.

Key questions that the PSE RIs help to answer for the progress of human knowledge are:

• What is the origin of the Universe and its constituents and how did they evolve to their present form? Is there a unified theory of the forces of nature?
• What are the conditions that enable life and is there life outside Earth?
• What is the nature of dark matter and dark energy and what is their connection to physics beyond the Standard Model of particle physics?
• What are the relationships between the functionality and properties of materials and their atomic structure and dynamics?
• How to engineer new materials with unprecedented properties?

Answering these questions underpins the vision of scientific research in the PSE domain and defines the mission of the PSE RIs. However, gaps remain in the landscape that should be filled to satisfy the scientific needs to answer these questions. Table 1 provides a view of the vision and gaps against the relevant ESFRI PSE programme, with non-ESFRI large scale international RI’s programmes also contributing to address some of the questions.

PSE RIs share technologies, tools and practices that go beyond thematic disciplines and constitute a solid basis for effective cooperation. Sharing technologies increases the efficiency of the RIs while lowering their overall cost.

The data and data analysis chain – FAIR principles (Findability, Accessibility, Interoperability, and Reusability), big data, open data, open software, deep learning, etc. – and enabling technologies for interoperability and digitalization are exemplars. However, despite the Big Data challenges pressing on the field, a common limitation is that funding of the data and computing infrastructure is not always included in the RI initial cost estimate. The large experiments of Particle & Nuclear Physics, through their needs for massive data transfer, storage and processing, drive the field of Big Data. The complexity of the data structures requires development of sophisticated data analysis approaches based on artificial intelligence methods. Quantum computing, although still far from practical implementation, offers the potential to solve specialized tasks much more effectively than conventional methods. At the Analytical Physics facilities, the brilliance increase enables higher throughput of samples with higher resolution by employing faster and larger detectors. The rapid growth of the data produced at these RIs creates needs for strategies to transfer, store and treat Big Data. Also, the increasing number of multidisciplinary users demand new fast and reliable tools for analysis of large datasets. Use of artificial intelligence as well as standardisation in the hardware and software will aid progress toward this goal.

Technologies developed specifically for the needs of RI often spill-over to other fields, finding widespread cross-disciplinary applications with a large impact on society and citizens. Particle & Nuclear Physics requires accelerators at the forefront, new types of detectors with increased resolution and sensitivity, and highly efficient systems for acquisition, storage and processing of some of the largest data-streams ever encountered. These front-line technologies ultimately find their way into numerous applications in medical imaging and therapy, advanced detection and diagnostic methods, environmental science, computing etc. The methods of Particle & Nuclear Physics are closely related both in terms of science and in technology, but have significant overlaps with many other fields in astroparticle, astronomy, material science, real-time chemistry and biology. Closer cross-disciplinary exchanges are burgeoning and should be further reinforced. The selection of common tools in Table 2 shows the crossing between thematic areas.

The PSE RIs provide FAIR datasets of high reproducibility and quality as well as advanced data analysis methods and computational resources, contributing to drive the European Open Science Cloud (EOSC) and to make it workable. As demonstrated in astronomy, a global implementation of a FAIR disciplinary framework and openly available data, the so-called astronomical Virtual Observatory, enables exploitation of the data produced by the Infrastructures by any scientist around the world, and provides access to premium scientific data also to citizen scientists. RI services, however, should evolve to cope with the new needs of FAIR data, effective Interactive Remote Access (IRA), and mission-originated demand for research. This evolution requires significant strengthening of the skilled human resources available at RIs, to make IRA and mission-driven research possible. Boosting in-house science capability can better support the wider research community. New access schemes, different from the traditional model of users’ originated projects, should be developed. The model of remote observation, common in Astronomy, could be more widely applied to the other domains. In the case of analytical facilities, protein crystallography has shown that robotized beamlines and mail-in samples can tremendously improve the throughput in standardized measurements. On the other hand, in certain highly specialized experiments, users and their hands-on expertise will still be needed to be present at the facility. Nevertheless, IRA technologies, from real-time on-line remote connection to augmented reality technologies, should be implemented to make the user control of remote experiments as effective as possible. This would improve the productivity of RIs while guaranteeing efficient training for young researchers. Increasing human resources at RIs can be pursued in various ways. A further increase in PhD students carrying out their research program at RIs, and Post-Doctoral positions at RIs, would reinforce the RIs as research and knowledge hubs in cooperation with universities and industries. RIs can play an increased role in preparing and training skilled young scientists and technology developers, as innovation-ready employees of industry and civil services.

REINFORCING RI COLLABORATION THROUGH NEW MODELS Interconnection of RIs can occur spontaneously via clustering and joint offering of services such as common developments of protocols for FAIR data and services. The EOSC will be an element of evolution of the landscape. Interoperability of RIs is a new organizational and technological frontier enabling overarching research programmes beyond the measurement or observation session model and widening the portfolio of services for the users community. Clustering is powerful in enabling synergies between the ESFRI RIs, including sharing of technologies and best practices. A framework should be established to encourage such endeavours under Horizon Europe, beyond the current cluster projects.

The Astronomy ESFRI & Research Infrastructure Cluster project (ASTERICS, 2015- 2019) successfully gathered the Astronomy & Astroparticle ESFRI RIs. Enhancing their performances beyond the state-of-the-art, it demonstrated the power of building synergies and common endeavours between the ESFRI RIs. ASTERICS was succeeded in 2019 by the European Science Cluster of Astronomy & Particle Physics ESFRI Research Infrastructures (ESCAPE) – one of the five EOSC-related Clusters, which includes the European Organization for Nuclear and Particle Research (CERN), and the European Southern Observatory (ESO). ESCAPE also brings on board other world-class established astronomical observatories, such as those operated by ESO (e.g. APEX, ALMA, the Paranal and La Silla observatories) and other Research Infrastructures including the European Gravitational-Wave Observatory (EGO-Virgo) and the Joint Institute for VLBI ERIC (JIVE), and the European Virtual Observatory teams.

Along with clustering of thematic RIs, a new model of multiple exploitation of broadly thematic RIs to pursue scientifically focused goals is proposed by the Analytical Research Infrastructures in Europe (ARIE)Analytical Research Infrastructures in Europe - A key resource for the five Horizon Europe missions, Joint Position Paper. Pre release 8 July 2020
https://www.lens-initiative.org/wp-content/uploads/2020/07/ARIE-PosPaper-2020-07-07-14.00.pdf position paper, where the alignment and exploitation of the wide range of services available at the RIs enable to meet the five Horizon Europe Missions, i.e. climate change, cancer research, climate-neutral and smart cities, healthy oceans, seas, coastal and inland waters, as well as soil, health and food. There are seven European networks under the ARIE umbrella representing about 120 national and international research facilities, including all the thematic ESFRI Projects and Landmarks: the League for European Accelerator based Photon Sources (LEAPS)League for European Accelerator based Photon Sources (LEAPS)
https://leaps-initiative.eu/ brings together the European accelerator based light sources, the European Distributed REsearch Infrastructure for Advanced Electron Microscopy (e-DREAM) collects the major actors in electron microscopy, LaserLab-EuropeLaserLab-Europe
https://www.laserlab-europe.eu/ coordinates the laser infrastructures, the League of advanced European Neutron Sources (LENS)League of advanced European Neutron Sources (LENS)
https://www.lens-initiative.org/ the neutron facilities, EMFL the high magnetic field facilities, and INSPIRE the proton and RADIATE the ion facilities. These networks thrive to create common tools for data, expand user communities, advance the technologies, and access models including industrial use. This is a joint effort undertaken within the networks and, under the ARIE umbrella, crossing the networks.

A pioneering approach towards the exploitation of complementary techniques was proposed by the NFFA-Europe model, now the newly funded NEP (NFFA-Europe Pilot) project for nanoscience, and the CERIC ERIC model in material and life science. NEP provides a rich catalogue of services and instruments to researchers who can access the theoretical and experimental facilities needed for their project. Thematic infrastructures, intrinsically distributed and multidimensional – highly specialized academic laboratories, large clean room facilities, large fine-analysis installations – that are already part of the landscape will most likely evolve into more structured and integrated organisations with the potential of extending PSE resources and methods to other fields of research such as life sciences.

Recent studies assess the overall economic impact of research carried out at RIs. This is complex as the technological innovations or scientific discoveries enabled by the PSE RIs extend over long time scales, up to decades after the invention or the findingSTFC Impact Report 2018
https://stfc.ukri.org/files/stfc-impact-report-2018/ . Indicators have been proposed to guide the studies of economic impact of research at RIs. One of the most recent studies was carried out by the Centre for Economics and Business Research (CEBR) for the European Physical Society and published in 20196The Importance of Physics to the Economies of Europe -A study by CEBR for the period 2011-2016 (2019)
https://www.eps.org/page/policy_economy. According to this report, physics-based industries generate more than 16% of total turnover and 12% of the overall employment in Europe, thus representing a net annual contribution of at least 1.45 trillion EuroCERN Courier July/Aug 2020
https://cds.cern.ch/record/2722711/files/CERNCourier2020JulAug-digitaledition.pdf . Evaluation of the wider impact of RIs on society and economy should include the returns on discoveries and technology that sometimes find applications well beyond the initial targets, apart from the easier evaluation of the returns on RIs construction budgets that, in a variable measure from 40% to 60%, flow back into industries and companies of the partner countries through the procurement of supplies and services. The large innovation potential of technical solutions, for example, in detector and accelerator technologies, data handling, or remote control, is often exploited also for commercial applications and act as boosters for new applications and new practices.

RIs play key roles in training, higher education and communication to society and citizens. As hubs of knowledge and centres of excellence, RIs are crucial for advancing skills by giving access to cutting-edge facilities and providing opportunities for students and young researchers to specialise and develop their careers in stimulating environments. Collaboration platforms with European universities and research organisations are an important instrument to strengthen the link between education and research while stimulating the competitive excellence profile of the RIs through a beneficial and sustained injection of young, motivated researchers. The constructive links between RIs and universities are also apparent from the provenance distribution of the users, which in large percentages are M.Sc. and PhD students, and the European RIs serve many thousands of international users.

The overall evaluation of the users community size provides numbers as high as 30,000 for the Particle & Nuclear Physics area, at least 30,000 for Astronomy & Astroparticle PhysicsData from the astronomical facilities is open to the global community after a proprietary period, hence the relevant user community is the global astronomical community. The minimal number of potential users from the A&AP community is derived from the number of authors of the articles published in the 7 main journals of the field on one year (private communication from the Astrophysical Data System, the reference bibliographic database for astronomy), and 40,000 for Analytical Physics. PSE users very positively adopted the access modes developed to mitigate restrictions to mobility, actively collaborating to implement interactive remote participation in the actual conduct of experiments. That prepares the ground for a transformative usage of the RIs enforcing the resilience of the transnational access paradigm.

To strengthen the public perception of the RIs value in everyday life, well-structured plans for communicating the unique scientific achievements enabled by the RIs are developed, explaining clearly the returns in knowledge, technology and education for the benefit of society.