FCC week 2022 will bring together the worldwide community working towards a world-leading high-energy physics infrastructure for the 21st century. The meeting covers Accelerator, Detector and Physics studies as well as progress on Technological R&D, ongoing placement studies and the assessment of its environmental and socio-economic impact.
Taking place in a hybrid format, the meeting will give the opportunity to share results, build new collaborations and solidify the vision of a post-LHC circular particle-collider. Furthermore, the meeting will offer opportunities to discuss and plan activities in the framework of the EU-funded H2020 FCCIS project.
The event will follow the traditional layout of plenary and parallel sessions with invited contributions. Plenary sessions will give an overview about the ongoing activities across all parts of the study and serve to inform study members about the updated boundary conditions from placement studies, the latest machine parameters and progress on understanding the physics potential that the FCC integrated programme can offer during its lifetime. Parallel sessions will focus on specific areas of the study. Satellite meetings for related projects and governance bodies of the FCC study will be included in the programme that is being developed. Participation of industry is highly encouraged as addressing the technological challenges of a new research infrastructure presents opportunities for co-innovation.
The work carried out in the framework of the FCC Feasibility Study will inform the next update of the European Strategy while can have an impact on areas beyond particle physics. Thus we invite novel and innovative approaches to address the challenges of the FCCs and contribute in turning them to reality. We strongly encourage colleagues working in the different areas covered by the FCC study to submit their abstract and posters. We invite you to register now, to join these efforts, and to contribute with your expertise to the efficient and sustainable implementation of these marvellous future machines.
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FCCIS – The Future Circular Collider Innovation Study. This INFRADEV Research and Innovation Action project receives funding from the European Union’s H2020 Framework Programme under grant agreement no. 951754. |
Since the last FCC Week conference, the layout of the FCC tunnel has been further optimized to provide a more favourable placement in the Geneva Basin.
Compared to the layout used in the Conceptual Design Report, the new tunnel layout now features a slightly smaller circumference of 91 km, but is compatible with four experimental insertions.
In this presentation, we present the latest layout and beam optics for the FCC-ee collider ring, adapted to the new tunnel layout and with four interaction points.
Based on input from studies on collective instabilities, the arc cell layout and IR optics were modified and changes will be summarised in this talk.
The parameters for the new layout, the dynamic aperture, and next steps will be discussed.
In order to achieve its ultra-low vertical emittance (1 pm) and high luminosity (of up to $230 \times 10^{34}$~cm$^{-2}$~s$^{-1}$ per collision point), the e$^+$e$^-$ Future Circular Collider (FCC-ee) requires a well-informed alignment strategy, powerful correction methods, and good understanding of the impact of vibrations. The large ring size, high natural chromaticity, small $\beta^*$, and the low coupling ratio make the FCC-ee design susceptible to misalignment and field errors, which if not properly addressed, threaten to increase the horizontal and vertical emittances and adversely affect the luminosity. Tight alignment tolerances around the 100 km ring would be a major cost driver and therefore alignment and stability need to be carefully studied. I will present a status update of the emittance tuning simulations for the 4IP ttbar lattice.
In order to maximize the integrated luminosity of the FCC-ee, top-up injection will be employed. The positron and electron beams will be accelerated to the collision energy in the booster ring before being injected into the collider ring where it will merge with the stored beam. Regular injection maintains an effectively constant beam current and, other than a brief period during the injection process, collision data can be continuously acquired. Two suitable schemes for FCC-ee, each with on- or off-momentum sub-schemes, have been identified in the past and are studied in further detail to find a suitable design for each of the four operation modes of the FCC-ee.
Increasingly funders of public investment in science and technology require applicants to demonstrate the expected socio-economic returns of their projects. While the scientific case is obviously the top priority for researchers when they propose a new project, it is helpful to know why and how the funders have an interest on impact studies, and what is the potential reward for scientists to be able to provide the required evidence. The talk will present opportunities and requirements by the European Commission, European Investment Bank, ESFRI and other international and national funders of science and technology.
Building on international practice and previous experience in evaluating the socio-economic impacts of Big Science projects, a model to estimate the future impacts of FCC-ee has been developed. This presentation will recall the definitions of the impact pathways considered and the fundamental assumptions used to perform the analysis.
The FCC innovation study requires an analysis to better understand the impact that FCC-ee will have on supplier companies, and the mechanisms through which the procurement relationship might generate benefits for the industry. By capitalising on previous research on (HL-)LHC, the presentation provides preliminary results of a new analysis where the economic multiplier of the FCC-ee procurement is calculated, and its drivers unveiled.
In its basic modes, FCC-ee is a factory for Z and W bosons, the Higgs scalar, top quarks and flavoured Standard Model particles. As a consequence, with FCC-ee we will be able to test in clean and precise experimental conditions the entire spectrum of the Standard Model electroweak physics programme. On top of that, the anticipated electroweak precision studies will allow us to set up a discovery programme which goes beyond the Standard Model. From a bird’s eye perspective, the physics plan includes searching for new elusive particles that could interact extremely weakly, or unveiling the existence of new heavy particles by their indirect (virtual loops) effect on ultra-precise measurements.
In the talk, I will highlight both the precision and discovery aspects of the physics programme and the main theoretical challenges which are ahead of us.
Collective effects due to the high beam intensities in FCC-ee, in particular for the Z-pole configuration, are very important for reaching the design performance. While resistive wall represents a major source of impedance for such a large machine, also other contributions, such as that of the bellows with included RF fingers, cannot be neglected. We have studied the single beam instabilities in the longitudinal and transverse planes produced by the impedance devices evaluated so far, as well as possible mitigation effects due to chromaticity and feedback system.
Additionally, the interplay between beam-beam interaction, beamstrahlung and the longitudinal beam coupling impedance has a strong influence on the coherent X-Z instability, it may reduce the stable tune region, and it must be carefully analyzed.
Collective effects are very important for the FCC-ee collider due to very extreme parameters, such as the high beam current. Taking into account the updated impedance model, new results of beam dynamics simulations for FCC-ee will be presented. We will analyse the longitudinal microwave instability threshold studying bunch length and energy spread versus beam current, and TMCI, transverse mode coupling instability, by means of PyHEADTAIL. We also review the TMCI threshold by considering the variation of the chromaticity. Finally we will discuss the effect of the bunch-by-bunch feedback system on the TMCI threshold.
In this work, we present updates on the electron cloud build-up studies considering various sections of the FCC-ee. Additionally, we report arc dipole & drift regions using the new baseline beam parameters for four IPs. Furthermore, estimated threshold central electron densities for the single-bunch instability are included. The electron density at the center of the beam pipe for 30 ns and 32 ns bunch spacings, secondary emission yield, and photoemission yield parameters are given.
The Future Circular Collider (FCC) is a post-LHC project aiming at direct and indirect searches for physics beyond the SM in a new 100 km tunnel at CERN. In addition, the FCC-ee offers unique possibilities for high-precision studies of the strong interaction in the clean environment provided by e+e- collisions, thanks to its broad span of center-of-mass energies ranging from the Z pole to the top-pair threshold, and its huge integrated luminosities yielding $10^{12}$ and $10^8$ jets from Z and W bosons decays, respectively, as well as $10^5$ pure gluon jets from Higgs boson decays. In this contribution, we will summarize studies on the impact the FCC-ee will have on our knowledge of the strong force including: (i) QCD coupling extractions with permil uncertainties, (ii) parton radiation and parton-to-hadron fragmentation functions, (iii) jet properties (ligh-quark-gluon discrimination, e+e- event shapes and multijet rates, jet substructure, etc.), (iii) heavy-quark jets (dead cone effect, charm-bottom separation, gluon-to-cc, bb splitting, etc.); and (iv) nonperturbative QCD phenomena (color reconnection, baryon and strangeness production, Bose-Einstein and Fermi-Dirac final-state correlations...).
In this contribution we will give an overview of the status of the design of the pre-injector complex and introduce the new layout that has been proposed by the study group working in the context of the CHART collaboration. A summary of the injector parameters focusing on the most challenging ones for the different injector sub-systems will also be presented.
In this presentation, I will give an overview of the beam dynamics simulations done to optimize the design of two of the linacs in the FCC-ee injectors’ complex. The first one accelerates electrons from 200 MeV up to 1.54 GeV, and for both electrons and positrons from 1.54 GeV up to 6 GeV. In particular, I will focus on some of the possible mechanisms of single-bunch emittance degradation and multi-bunch beam breakup. Furthermore, I will discuss several options to minimize the projected energy spread, necessary for the acceptance at the SPS or Booster ring injection.
The linacs of the FCCee injector complex will both provide the drive beam for position production and accelerate nominal electron and positron beams up to 6 GeV. Several linacs comprise different traveling-wave structures fulfilling the beam dynamics and RF constraints. High-phase advance large-aperture structures accelerate the positron beam at low energies. All structures are rotationally symmetric for easier production. Long-range wakes are damped by HOM detuning. Operating mode and HOM parameters were calculated based on lookup tables and analytic formulas, allowing for rapidly scanning large parameter spaces. Here, we present both methodology and the current state of the RF design of the structures.
I will motivate the BSM theory case for the FCC physics programme and give a general outline of the various scenarios it will be able to explore to an unprecedented level.
Invited talk
The two stage FCC program with electron positron and proton proton collision offers a unique opportunity to search for long lived particles in a clean electron positron environment as well as in high energy high luminosity proton proton collisions. I take an overview of the opportunities for searching for long lived particles both at FCC-ee and FCC-hh. I present several examples of motivated physics scenarios featuring long lived particles and sensitivity of FCC program to the corresponding parameter space.
The electron-positron stage of the Future Circular Collider, FCC-ee, is a frontier factory for Higgs, top, electroweak, and flavour physics. It is designed to operate in a 100 km circular tunnel built at CERN, and will serve as the first step towards ≥ 100 TeV proton-proton collisions. In addition to an essential and unique Higgs program, it offers powerful opportunities to discover direct or indirect evidence of physics beyond the Standard Model. Direct searches for long-lived particles at FCC-ee could be particularly fertile in the high-luminosity Z run, where $5×10^{12}$ Z bosons are anticipated to be produced for the configuration with two interaction points. The high statistics of Higgs bosons, W bosons and top quarks in very clean experimental conditions could offer additional opportunities at other collision energies. Three physics cases producing long-lived signatures at FCC-ee are highlighted and studied in this talk: heavy neutral leptons (HNLs), axion-like particles (ALPs), and exotic decays of the Higgs boson. These searches motivate out-of-the-box optimization of experimental conditions and analysis techniques, which could lead to improvements in other physics searches.
Current strategy and ongoing activities will be presented, in relation to R&D and preparation of production for the elliptical cavities needed by FCC
In the frame of the Future Circular Collider (FCC) study, CERN is modelling the copper electropolishing process. The aim is to foresee and optimise the process parameters such as cathode geometry, bath flow and temperature, and minimum potential input, namely on the 400 MHz single cell FCC type cavities and thus contributing in achieving the ultimate performance on the Nb/Cu technology. In this contribution, it’ll be presented the current simulation results both on the 1.3 GHz and 400 MHz and on-going benchmarking work.
Since the late 80’s, CERN has pioneered development of thin film superconducting radio-frequency cavities for particle accelerators. This technology, used in LEP II, LHC and more recently in HIE-ISOLDE, presents many advantages. As a consequence, many efforts are put in place at CERN in view of its potential implementation in the FCC machines. However, niobium thin film cavities historically feature a strong increase in surface resistance with accelerating field, resulting in a progressive degradation of performance.
The goal of our work is to expand the range of potential applications of niobium coated copper cavities by pushing their present limits. Our current strategy attempts to optimize the copper substrate of 1.3 GHz cavities for the niobium film deposition in order to achieve performance competitive with that of the state-of-the-art bulk niobium cavities. In parallel to the characterization of niobium-copper cavities by standard measurements of the surface resistance and the penetration depth between 1.9 K and 9.3 K, a temperature mapping system is used to detect the mechanisms responsible of performance degradation. Unlike most of the temperature mapping systems currently in operation, this system is specially designed for copper coated cavities. Since the thermal diffusivity of copper is noticeably high at liquid helium temperatures, the detection of heat losses in copper coated cavities turns out to be extremely challenging in comparison to that in bulk niobium cavities. We will report how we overcome this limitation in order to cope with our requirements. Furthermore, temperature maps of niobium-copper cavities, tested at CERN, will be shown.
The Future Circular Collider (FCC) study focuses on the design and technology developments of a new research infrastructure capable of hosting the next generation of particle colliders at CERN. CERN developed significant know-how in the design and fabrication of niobium-coated copper superconducting radiofrequency (SRF) cavities for accelerators, from the Large LEP, to the LHC, and HIE-ISOLDE. Niobium thin-film on copper technology was a reliable option for these projects, complying with the performance criteria established for SRF cavities. While 400MHz Nb-coated Cu cavities are being considered for the leptonic machine variants of the FCC, further performance optimization is required as their quality factor suffers a strong decrease with increasing accelerating fields. To comply with FCC specifications, their performance must be optimized so that they can sustain accelerating fields up to 10 MV/m with quality factors Q0 above 2x109, while maintaining the operational temperature at 4.5K.
The work presented focuses on recent R&D efforts performed at CERN on the Nb thin film-coatings, to ultimately raise the performance of the Nb/Cu cavities, as they constitute key elements to achieve running-feasibility for the FCC. Fundamental studies performed on samples, where correlations between specific deposition parameters and the morphology, crystalline structure and superconducting properties of the films were found, will be summarized. Recent advances and planned activities on the 400MHz Nb/Cu coatings program at CERN will also be presented.
The Nb/Cu SRF cavities offer several advantages with respect to the bulk Nb cavities. However, their application has been limited due to a degradation in the performance systematically observed at high accelerating gradients. In recent years, a vast R&D campaign has been devoted to the optimization of the manufacturing process of 1.3 GHz cavities at all levels, from the production of the substrate to the application of the coating. RF tests performed at the CERN's cryogenic laboratory (cryolab) have been key to guide the decision-making to modify accordingly the manufacturing process, aiming at improving the performance of the cavities to meet the operational specifications of the FCC SRF system. As a proof of success of this R&D campaign, a cavity achieved unprecedented performance with mitigated Q slope at 1.85 K. In this presentation, an overview of the evolution of the RF performance of the cavities will be given together with the optimization of the process followed.
CERN has successfully operated a number of Nb coated Cu cavities for a number of years, most notably in the LEP, LHC and HIE ISOLDE accelerators. In order to meet the requirements for the Future Circular Collider (FCC), an increase in the quality factor of the accelerating cavities, while maintaining the operating temperature of 4.5 K, is required. Because of its lower BCS resistance and increased critical temperature of 18.3 K, Nb3Sn is a potential candidate to allow coated Cu cavities to achieve these requirements. The feasibility of depositing Nb3Sn films onto Cu substrates using DC MS has previously been demonstrated at CERN. The resultant films displayed good RF performance and a critical temperature up to 16 K [1]. Given the superconducting performance improvements observed with HiPIMS-deposited Nb films, its use in the synthesis of Nb3Sn films was proposed.
This work focuses on the elaboration of Nb3Sn films on Cu substrates using the bipolar HiPIMS technique. A variety of deposition parameters were explored in order to deposit a stable A15 phase. The influence of the deposition parameters on the resulting film morphology, crystalline structure and superconducting properties were studied. The challenges experienced due to the use of Cu as a substrate as well as methods for overcoming these will also be presented.
[1] E. A. Ilyina et al., “Development of sputtered Nb 3 Sn films on copper substrates for superconducting radiofrequency applications,” Supercond. Sci. Technol., vol. 32, no. 3, p. 035002, Mar. 2019, doi: 10.1088/1361-6668/aaf61f.
The presentation shows a simulation and optimisation of the FCC-ee positron source using a high-temperature superconducting (HTS) solenoid as the matching device to collect positrons downstream of the target. The conventional target scheme composed of simply a single tungsten is used. The target is placed inside the bore of the HTS solenoid to improve the positron yield. The position of the target is optimised. The latest recommended baseline beam parameters are also presented and used in the study. The accepted positron yield at the entrance of the damping
ring has been significantly improved compared with the flux concentrator matching device.
For an electron-positron collider like FCC-ee, the production of positrons plays a crucial role. One of the design options considered for the FCC-ee positron source employs a superconducting solenoid made of HTS coils as an adiabatic matching device. A superconducting solenoid yields a higher peak field than a conventional flux concentrator, therefore increasing the achievable positron yield. Furthermore, in order to achieve an acceptable positron production, the considered target is made of tungsten-rhenium. However, superconducting coils exhibit a higher sensitivity to the radiation load. In this study, we assess the feasibility of such a positron source by studying the heat load and long-term radiation damage in the superconducting matching device and surrounding structures. Results are presented for different geometric configurations of the superconducting matching device, considering different shielding geometries and target positions.
The current status of the DR design will be presented with an analysis of the impact of the timing scheme of the injection and its implication on the DR injection/extraction equipment, moreover, a review of the acceptance of the DR in the longitudinal and transverse planes will be analyzed and the implication for the positron source will be addressed.
This work presents the concept of the HTS solenoid-based adiabatic matching device for the CHART FCCee Injector study. The first results of in-house made and tested non-insulated HTS coils are shown.
The CHART P-cubed project at Paul Scherrer Institut is the proposed proof-of-principle experiment for the FCC-ee positron source. The main challenge for this study is capture and transport devices of the secondary positron beam from the production target to the damping ring. To meet the requirements of the experiment, a novel approach using HTS-based NI coils for the matching and focusing solenoid magnet is proposed.
This technology takes the advantage of the high current density, high stability, and relatively straightforward cryogen-free cooling at ~20 K producing considerably higher positron yield with respect to the state of the art. Conventional insulation could be subject to irradiation damage, and constitute a thermal barrier for the extraction of heat from the coil. All of these make solder-impregnated NI coils ideally suited for compact DC applications. For this reason, PSI has licensed NI coil technology from Tokamak Energy Ltd (TEL) and applied it in a first demonstrator solenoid.
Here we present the design, coupled thermo-electromagnetic modeling, and powering results of the first HTS NI solenoid demonstrator, built and tested in-house with TEL technology. The new cryogen–free teststand upgraded and redesign for this project will be shown too. It’s equipped with two cryocoolers, allowing for powering tests up to 2 kA with FPGA based quench detection system.
Work supported by the Swiss State Secretariat for Education, Research and Innovation SERI and the ETH Board.
The current proposal for the FCC-ee injector complex includes separate linacs to accelerate the electron and positron beams to 1.54 GeV, followed by a common linac to bring the beams to 6 GeV. Electron and positron transfer lines will be needed to connect these elements. There will be a damping ring for the 1.54 GeV positrons, after which a transfer line will transport the positron beam to the common linac, including a section for bunch compression. Here we present the status, results and outlook of studies for the transfer lines, as well as some of the considerations for the injection and extraction systems.
P-cubed, currently in development at PSI, is the proposed proof-of-principle experiment for the FCC-ee positron source. Capture and transport of the secondary positron beam from the production target to the damping ring are a key challenge for FCC-ee, due to large emittance and energy spread. The use of novel matching and focusing methods has been studied, such as high temperature superconducting (HTS) solenoids, where recent simulations show considerably higher positron yield with respect to the state of the art.
To exploit this potential, the goal of P-cubed is to test an innovative technological approach and validate a high-yield positron source for FCC-ee. The experiment is to be hosted at SwissFEL, where a 6 GeV electron beam and a tungsten target can be used to generate the positron distribution. Such beam will be captured through an arrangement of a HTS solenoid-based Adiabatic Matching Device, two standing-wave cavities in S-band and four solenoids surrounding such structures. Thus, several technological alternatives are discussed and the baseline design for the experiment is proposed.
One of the main objectives of FCCee is the precise measurements of Standard Model parameters, like the couplings of the Higgs boson to the bottom and charm quarks and gluons. This requires an efficient reconstruction and identification of the hadronic final states of these processes, which entails identifying the flavour of the parton that initiated the jet, referred to as jet-flavour tagging. Efficient and accurate jet-flavour identification is also necessary to assess the feasibility of measurements such as $Z \rightarrow s\bar{s}$ or $H \rightarrow s\bar{s}$ and therefore is essential to utilise the maximal physics potential of future collider experiments.
This talk presents the ongoing efforts on jet-flavour tagging at FCCee and other future colliders. It discusses a few tagging algorithms based on different neural network architectures.
The aim of this work is to study the capabilities of the Futur Circular Collider (FCC) $ee$ phase to study the transitions $b\to s\tau^+\tau^-$ unobserved to date. At meson scale the decay $B^0\to K^*\tau^+\tau^-$ with the transition $\tau\to\pi\pi\pi\nu_{\tau}$ is studied with a method to reconstruct explicitly the two undetected neutrinos. The detector requirements to study this decay are evaluated, in particular the vertexing resolution performance. Some conclusions about the main drivers of the detector performance are drawn by means of the analysis of signal simulated sample. Finally, simulated samples of the most toxic backgrounds (coming from $b\to c\bar{c}s$ and $b\to c\tau\nu$) are injected in the system and allow the exploration of the feasibility of $b\to s\tau^+\tau^-$ measurement at FCC $ee$.
The innovative concept of two-stage multi-beam Klystron has been previously proposed and studied for a 1GHz 20MW Klystron for CLIC. This technology utilizes low voltage electron beam in its first stage to reduce the overall tube length, followed by DC post acceleration in the second stage to ensure ultra-high efficiency. This topology is very practical to provide compact design at a low frequency (UHF and L-band), high power (Multi Megawatt), high efficiency (>80%) klystrons. Hence the same concept was adopted for the development of a 0.4 GHz 1.2 MW Klystron for FCCee. In this report, the modelling and design study of the FCCee MBK with two-stage (TS) configuration is presented. Overall, the Klystron is expected to deliver a maximum power of over 1.2 MW with 80% efficiency. Preliminary design of the beam optics and solenoid has been done in 2D CGUN code. The interaction RF circuit was optimized using CERN-mad code KlyC and verified using 3D Particle-in-Cell simulation codes. The collector is designed to handle the full beam power dissipation in DC mode with maximal heat load of 500 W/cm2. The current status of TS MBK FCCee klystron development will be presented.
An innovative superconducting cavity topology has been recently proposed at CERN and at Lancaster University. It integrates longitudinal slots crossing perpendicularly the RF surface. The RF current lines run along the slots, inducing no perturbation of the accelerating mode. Thanks to this approach, the cavity can be built using halves or quadrants, which is well appropriate to precise manufacturing techniques. This configuration allows direct access to the RF surface, thus facilitating the surface preparation and thin film deposition process in the case of cavities based on Nb/Cu technology. The contact faces between the cavity parts are moved to the slots’ ends where the electromagnetic fields are extremely low, thus relaxing the constraints on the quality of the assembly joints. These presentations cover the latest development of a 600 MHz slotted elliptical cavity called SWELL, which has been proposed as an alternative option for the FCC-ee RF system as well as a simplified SWELL version of a single cell 1.3 GHz elliptical cavity and a new 6 GHz split resonator made of two halves for superconducting thin film characterization.
The recent measurement of the W mass by the CDF collaboration at the Tevatron in hadron collisions has created a significant buzz in the community. Quite apart from the fact that it disagrees significantly both with the Standard Model predictions and with previous measurements of this quantity, this result is remarkable by two aspects:
This poster will describe the work of the working group on centre-of-mass energy calibration at the Z and W pair threshold, with precision targets of a few keV, several orders of magnitude smaller than those achieved at LEP.
The Future Circular electron-positron Collider, FCC-ee, is designed for unprecedented precision for particle physics experiments from the Z-pole to above the top pair threshold. This demands a precise knowledge of the center-of-mass energy (ECM) and collision boosts at all four interaction points.
Synchrotron radiation losses range from 40 MeV per turn at the Z-pole with 45.6 GeV beam energy, and reach up to 10 GeV per turn at the highest beam energy of 182.5 GeV. The radiation losses lead to a variation of the beam energies over the circumference and thus to different ECM and boosts at each interaction point. Beamstrahlung enhances this asymmetry further. These losses are compensated by the RF-cavities, the location and settings of which
impact the energies. The ECM and boosts for various RF-configurations are presented here for different FCC energy stages.
Precise energy calibration is a key tool for the FCC-ee physics programme and will be obtained by resonant depolarization. It requires the implementation of a Compton polarimeter with unprecedented performance. The presentation is mainly devoted to the description of the foreseen laser performance and the associated challenges.
In this talk, I review the current status of the FCC-hh ring layout and optics studies, starting from a brief overview of the CDR status and then moving to the recent developments. I also provide an outlook for future studies and activities.
The FCC-hh will feature both an unprecedented stored proton beam energy
of about 8.3 GJ, more than an order of magnitude higher than the HL-LHC,
as well as superconducting magnets. This puts extreme demands on the
collimation system that should safely intercept any beam losses, since
even a tiny fraction of the beam carries enough energy to quench the
magnets or even cause damage. This talk shows the status of the studies
for the FCC-hh collimation system, with focus on updates since the last
FCC week, as well as an outline of future studies.
Inside the vacuum chamber of the FCC-hh, image currents will be induced in the beam screen due to its proximity to the particle beam. To ensure a stable beam trajectory, it is important that the surrounding material has very low surface resistance and that the magnetic field homogeneity is maintained in the central region of the vacuum chamber. To achieve this, our consortium explores the possibility of coating the beam screen with a highly conductive hybrid coating, made of alternating longitudinal segments of REBaCuO (RE = Rare Earth) and copper.
In this work, we use finite elements numerical analysis and a simulation model that accounts for superconducting properties of commercially available coated conductors to evaluate the field quality at the centre of the hybrid-coated vacuum chamber. We find a broad set of possible coating geometries that fulfil the field quality criterion, introducing field harmonics of the order of one unit or below, with or without an external correction of the dipole field. Samples of the hybrid coating are produced based on the geometries predicted by our model, showing lower than Cu surface resistance at close conditions to those found in the FCC-hh, confirming that this method can successfully generate a coating that complies with both field quality and surface resistance criteria. Finally, we analyse how field harmonics are affected by a misalignment of the beam screen.
The process of placing the ring has integrated from the beginning the Avoid - Reduce - Compensate approach.
The purpose of the presentation is to illustrate concretely how the ARC approach was implemented for the placement :
- How to avoid the main impacts?
- How to reduce the residual impacts?
- How to anticipate potential compensation needs?
For the design of FCC trajectory, a full understanding of the subsurface geology that will be crossed by both the tunnel and the access shafts is required. For this purpose a detailed knowledge of the regional distribution of rock mass composition and structural elements as well as the hydrogeological characteristics of the area should be achieved and summarised in a full-scale 3D geological model. In order to accomplish this task, a research project is being carried out at the Department of Earth Science of the University of Geneva with two goals: I) establish a Geographic Information System (GIS)-based subsurface data set and data base architecture in support of the feasibility and execution of the FCC tunnelling work by defining a standard data set framework for new data and II) establish a consistent high-resolution 3D geological model, supported by quantitative geological analytical investigations along the FCC trace aimed at predicting geological features and possible.
The 3D geological model to date provides a solid knowledge framework based on all available data known to date, highlighting the different lithological and structural heterogeneities crossed by the planned trace of the FCC tunnel. Specifically, the model allows the visualisation of the subsurface conditions known to date in the high risk areas identified enabling to take informed decisions during the forthcoming geotechnical and seismic investigation campaign which will take place across the French and Swiss border. Following this investigation campaign the geological 3D model will be updated with the new acquired data and will therefore provide more accurate view of the subsurface. This 3D model represents therefore a practical working tool which will support the FCC project throughout the different phases of tunnelling design, planning and execution.
To consolidate the physics case for the FCCee, complete detector concepts are necessary to estimate the expected physics performance in view of the beam and background environments. The CLD detector concept offers the possibility to study background and physics events in full simulation with sophisticated particle flow clustering algorithms. This presentation will describe the CLD detector geometry and highlight some of the performance achieved with its current iteration. It will furthermore offer some ideas for future optimisation studies to improve on the design.
The future circular electron-positron collider (FCCee) is receiving much attention in the context of the FCC Feasibility Study currently in progress in preparation for the next EU strategy update. We present IDEA, a detector concept optimized for FCCee and composed of a vertex detector based on DMAPS, a very light drift chamber, a silicon wrapper, a dual readout calorimeter outside a thin 2 Tesla solenoid and muon chambers inside the magnet yoke. In particular we discuss the physics requirements and the technical solutions chosen to address them. We then describe the detector R&D currently in progress and show the expected performance on some key physics benchmarks.
Coupled aperture magnet designs have been proposed for the dipole and quadrupole of the FCC-ee collider during the CDR phase. They are characterized by a high energy efficiency but the aperture coupling brings additional challenges to achieve the field quality requirements, in particular for the quadrupole when an active system is added to trim the field to the energy saw-tooth generated by the synchrotron radiation.
On the booster side, the magnet design studies are now starting and shall address operation in cycled mode and at very low fields.
The presentation will summarize the status of the collider magnet designs and explore design alternatives to address the challenges relating to the booster magnets.
The Future Circular Collider study program comprises several machine concepts for the future of high-energy particle physics. In particular, a twin-ring e-e+ collider capable to run at beam energies between 45.6 and 182.5 GeV is proposed as a first phase. The design of its two 100-km ring vacuum system has to deal with low-energy (45.6 GeV) high-current (1390 mA) version as well as the high-energy (182.5 GeV) low-current (5.4 mA) one. The limit for all the versions is given by the 50 MW/beam allotted to the synchrotron radiation (SR) losses. Beyond the vacuum challenges related to the synchrotron radiation and dynamic vacuum, the vacuum system shall have an affordable cost. The proposed technical solutions shall be defined considering these two aspects. The presentation will recall the main requirements and the concept of the vacuum system. It will outline the present technical developments in vacuum technologies potentially suitable for the FCC-ee vacuum system. In particular, shape memory alloy connector and cold spray technologies will be addressed.
Power converters are needed to supply all magnets and RF systems for the FCC-ee and FCC-hh. This needs to consider the required accelerator controllability and precision, as well as the electrical AC network power quality. The design procedure needs to minimise the total investment and operational costs (losses, availability, etc.). Aspects such as losses in underground areas, power converters and energy storage systems volumes and locations, and cable lengths, needs to be considered in a holistic approach.
The talk provides a summary of the initial works carried out, and in particular, presents the first ideas of a DC distribution concept, a draft and non-optimized FCC-ee power converters layout, and an analysis on energy storage systems suitable for the FCC-ee booster and FCC-hh.
Very high luminosities at the production poles (z,w,h,t) of FCC-ee are planned at the four Interaction Points (IP); thus very low beta star values are required at the IP, implying the use of very strong quadrupoles. Concurrently, LAPP work has underlined the strong correlation between the vibrations of the quadrupoles due to ground motion amplified by the dynamics of the cryostat in cantilever mode close to the Interaction Region (IR) and the variations of luminosity at the IP of SuperKEKB.
We are currently performing two distinct studies considering the z-pole optics design of FCC-ee. The first one consists to define dynamic vibrations tolerances and sensitivity in the Machine Detector Interface (MDI) region. Tracking simulations of a single beam circulating in the FCC-ee machine are performed with MAD-X, which undergoes a vertical time-dependent displacement of the first quadrupoles near the IPs. In parallel, studies have started on the effect of plane ground waves on the closed orbit of FCC-ee. A status of this frequential study will be given.
This presentation will briefly talk about error propagation in alignment networks in tunnels. It will also give a summary of alignment experiences that were reported at the FCC-ee optics tuning and alignment mini-workshop. Finally the presentation will show some results from SLAC in particular and the importance of alternate measurement methods added to conventional laser tracker and leveling measurements.
The presentation will show the techniques developed to perform commissioning-like simulations for the ESRF-EBS upgrade. In particular alignment specifications are updated respect to the past. Instead of specifying girder-to-girder errors, simulated surveys of the storage ring were used, providing a more complete and simple to use information. Also, the relative impact of different magnet families did not show anything particularly useful for installation and operation, and all simulations were thus resumed in a single final value. The described commissioning-like sequence of simulations is preliminarily applied to the FCC-ee V10 lattice optics, showing a less than trivial commissioning or tight alignment tolerance.
Simulations of non linear optics correction were done and tested in the ESRF Storage ring and simulated also for the FCC-ee ring.
A design is presented for the instrumentation of the very forward region in future detectors at e+e- collider to perform a fast estimate and precise measurement of the luminosity, to improve the hermeticity and mask the central tracking detectors from backscattered particles. Two compact calorimeters are foreseen, LumiCal and BeamCal. Both are designed as sandwich calorimeters with very thin sensor planes to keep the Molière radius small, facilitating such the measurement of electron showers in the presence of background. Silicon sensor prototypes and dedicated FE ASICs have been developed and produced. In recent beam tests, a multi-plane compact prototype was equipped with thin sensor planes, installed in 1 mm gaps between tungsten plates of one radiation length thickness, and fully assembled with readout electronics. The latest status of the calorimeter prototype development will be presented, including selected performance results, obtained in a 5 GeV electron beam at DESY, and compared the expected performance obtained from simulation.
The aim for the highest luminosities with the FCC-ee poses several constraints on the choice of the machine parameters. Unprecedented conditions are foreseen during beam-beam collisions which are expected to give rise to previously unseen dynamical mechanisms. The exploration and understanding of these effects as well as the identification of optimal working points are of crucial importance for the success of the FCC-ee feasibility study. To address these challenges using the latest computational technologies, a new general purpose software framework for beam dynamics simulations (called xsuite) is currently under development. This talk will focus on recent developments and benchmarking of FCC-ee beam-beam collision modeling using the xsuite framework.
The talk presents the status of MAD-X code and recent developments related in particular to FCC-ee studies.
A conceptual design for a collimation system in the FCC-ee is currently under preparation. The current focus is the design of a betatron and off-momentum collimation system, housed in a single insertion. The latest collimation configuration under study is presented. The development of collimation simulation frameworks for the FCC-ee is covered. The frameworks are based on a coupling between a particle tracking code, pyAT and Xtrack, and a Monte Carlo particle-matter interaction code, BDSIM (Geant4). Benchmarks against the SixTrack-FLUKA coupling framework without radiation and tapering, and preliminary loss maps with synchrotron radiation and tapering are presented, including a discussion of the results and future plans.
In short, Geodesy deals with two main topics. (1) The determination of the position of (all) objects on the Earth or in its vicinity. (2) The determination of the gravity field and its geometry. Since the beginning of mankind those tasks serve science and society. The first scientific question concerned the shape of the Earth, and the first societal application concerned the rational management of the territory with mapping. Today, the contributions of Geodesy are indispensable for the scientific understanding of the time-varying physical Earth system, and for the planning and construction of our modern infrastructures.
In this talk, an incomplete overview of the fundamental contributions of modern geodesy to science and society will be shortly presented. First, the fundamental reference coordinates systems and their application fields are shortly described. Second, the determination of the gravity field and its time-variation will be introduced. Finally, it will be shown how precise global geometry and gravity products lead to a better understanding of the system Earth.
Building the FCC tunnel will require outstanding engineering expertise from all domains involved. Several anticipated challenges will be comparable only to those encountered during the construction of the longest existing tunnels like the Gotthard Base Tunnel put into operation in 2016. With its length of 57 km it is still the longest railroad tunnel in the world. Its length, the complex topography and the heterogeneous geology, the simultaneous excavation from several locations, the high accuracy requirements for the tunnel breakthroughs, and the access through the over 800 m deep shafts at Sedrun presented major challenges to civil engineering and surveying. The surveyors were further challenged by the needs to account for an accurate geoid model in the Alps, and by the required monitoring of the earth's surface above the tunnel, in the vicinity of structures threatened by possible subsidence. When building the FCC, similar issues will arise and the experience gained from the Gotthard Base Tunnel will certainly be useful. The presentation will give an overview about these experiences.
For the construction and maintenance of large-scale infrastructure such as the Gotthard Base Tunnel or the CERN-FCC, it is vital to take into account the influence of the varying gravity field, because most geodetic measurements are referring to the local plumb lines and equipotential surfaces, deviating from purely geometrical positioning by e.g. GNSS.
The so-called Geoid, an equipotential surface of the gravity potential field, describes the idealized continuation of the mean surface of the oceans beneath the continents and is in general used as reference surface for the definition of physical heights. Different approaches exist to compute a local or regional model of the gravity potential field and the Geoid. Due to uncertainties, gaps in the measurements and simplifications in the modeling, existing geoid models differ by up to several centimeters in the FCC region. In this talk, the deviation between different geoid models available nowadays is shown and an overview to gravity field modelling using a selection of measuring instruments is given. Furthermore, the preliminary analysis of geodetic data (leveling, gravimetric measurements, deflection of the vertical and GNSS positions) collected along a profile, which was specifically selected to validate the calculated Geoid models, is presented.
The presentation will discuss the reasons why coordinate reference systems (CRSs) are needed for building and operating FCC. It will briefly summarize CERN's coordinate reference systems' diversity and historical heritage as well as the characteristics of the optimal coordinate reference system for the FCC. Additionally, key aspects for the implementation of the reference systems through geodetic networks over the LHC and FCC areas will be presented. These networks consist of sufficiently stable, materialized points with precisely determined coordinates that are accessible for a wide range of user needs, such as civil engineering and tunneling works, monitoring deformations, installation of machines, and others. The presented work is based on a collaboration and on exchange between experienced geodesist from CERN, academia, French and Swiss national geodetic institutions, and the industry. It thus combines the user needs with established best practices from different countries, and a projection of expected technological advances until the potential start of the FCC construction.
Building the FCC tunnel and installing each component of the machine at the intended location will be a challenging task relying notably on the quality and accuracy of the geodetic infrastructure. Before that, methods, tools and software must be developed to respond to the needs of the different parties taking part in the FCC feasibility studies.
This presentation will first cover the transformation of the beam trajectory of the FCC computed by physicists in the MAD-X software into the geodetic reference system that will be used for the construction and installation of the FCC. Then it will focus on the methodology to handle and unify the large amount of existing and newly acquired georeferenced data expressed in multiple coordinate systems.
This session will discuss recent ongoing efforts in the UK to facilitate discussions about future colliders within the early career researcher (ECR) community, and ideas to promote further discussions within the FCC community. In particular, it will describe an ECR forum that was hosted by the University of Birmingham in April 2022, involving a group of around 40 ECRs from around the UK. The event was divided into four sessions discussing the current physics landscape (including anomalies), accelerator and detector technologies for future colliders, the funding landscape and steps involved in starting new collaborations and opportunities and challenges for ECRs doing R+D for future experiments.. Following this meeting the organizers are now aiming to arrange a follow-up event within the UK ECR community to further support discussions on this topic. The hope is that sharing the experiences of the organizing committee for this event (which was entirely composed of ECRs) with the FCC community will inspire further initiatives in this area. Some of the interesting lessons and insights raised in the session will also be discussed. This session will be run interactively, with opportunities for discussion amongst those present, both on the topics presented and the experiences of ECRs from across the FCC community.
Two possible scenarios for measuring the frequency of spin precession in FCC-ee storage rings at the threshold of the birth of Z and WW-pairs are discussed. One of the scenarios involves the use of the well-known method of Resonant Depolarization of pilot bunches of the pre-polarized particles. While in the second approach it is proposed to use a powerful short-pulse RF magnet (flipper) to quickly rotate the direction of spins away from the initial vertical one and then measure the modulation of the laser polarimeter counting rate by the frequency of free precession of electrons or positrons leaving the stored beam. The second method uses an almost 100% dependence of the cross section of the inverse Compton scattering on the longitudinal spin component of electrons and positrons, which makes it possible to observe the coherent precession of particle spins and isolate the frequency of this precession in the Fourier spectrum of the polarimeter signal.
The base line for the RF system of FCC-ee is a combination of 400 and 800 MHz systems operating at 4.5 and 2 K respectively. The system is designed to evolve for the different working points of the machine. Taking into account constraints from beam physics, placement and infrastructure, we have identified two straight sections to house the cryomodules. This presentation outlines the constraints and design choices and proposes a base line scenario.
The Future Circular Electron–Positron Collider (FCC-ee) will be 91 km long and operate in a top-up mode where new beams are continuously injected into the collider. For this purpose, the collider tunnel will also house a 91 km long booster accelerator. During its life cycle, the FCC-ee will operate with different energies to study Z, W, and H bosons and the top quark. The Future Circular Electron–Positron Collider (FCC-ee) will house two Radio Frequency (RF) systems at point L and at point H. Point L will house the 400 MHz cavity and 800 MHz cavity. Point H will house only 800 MHz cavity.
To manage and ensure the 3D space of the elements, including the reserved volume (e.g. transport, handling, survey), integration studies on the machine configuration and layout are progressing with 3D models and corresponding cross-sections. The presentation will give an overview of the RF cavities implementation and their associated connections at point H and point L, with respect to the booster line, general services layout and reserved volume.
Now entering its phase II, the FCC Study capitalizes on the work of the Conceptual Design Report to refine its results, to serve as input for the next ESPP Update in 2026/2027.
Considering recent adjustments that have been made to the accelerator conceptual design, the architecture of the cryogenic systems for both FCC-ee and -hh machines is currently under revision and shall be updated.
From the recent review of the accelerator layout to the ongoing work on the RF cavities design, there is an important amount of new process data to consider that are directly impacting the design of the cryogenic infrastructure.
This presentation will first recall the current status of the study, with an emphasis on the cryogenic architecture foreseen for the lepton collider. The proposed update of the cryogenic infrastructure, layout, implementation and process will be addressed, taking into consideration the modification of the layout of the accelerator and the heat loads issued from the main users, while focusing on the encountered integration issues. Availability requirements of such a facility will be investigated. Consolidated organization of the cryogenics work package will be presented, including tentative timeline and upcoming objectives.
The world (both natural and man-made) is a complex, unstructured, cluttered and dynamically changing environment, in which humans and animals move across varying terrain (towns/cities, industrial infrastructures, countryside, forest, mountains, etc.) easily changing their gait, behaviours and motions, while performing simple and complex tasks involving coordination of the arms, body and legs.
Robots that have the potential to assist, augment or replace humans performing inspection, upgrades, maintenance and ensuring safe operation particularly in the complex, hazardous infrastructures that are typical at CERN, form one of the holy grails of robotics.
For robots to operate in these complex facilities using tools designed for humans, requires human/animal inspired agility, compliance, dexterity, robustness, reliability and movement/locomotion (loco-manipulation). However, there remain many fundamental robotic questions in areas such as: robot design, actuation, power and energy efficiency, motion and locomotion control, gait generation, perception, sensing, etc.
At the Italian Institute of Technology (IIT), research over many years has led to the development of a wide range of mechatronic systems designed with a focus on inspection, maintenance, repair and upgrading of hazardous sites. Robots developed at IIT include: the HyQ quadruped family, humanoids such as iCub, cCub, COMAN, WALKMAN, and COMAN+, the centaur robot PHOLUS, and continuum and small space investigation robots. This presentation will start to explore the potential of these and future generations of robots for applications around the development and operation of the FCC.
At CERN we heavily use robots for inspection, maintenance and repair tasks throughout our accelerator complex, facing challenges of hazardous environments, cluttered areas, changing conditions and limited communication channels. To support these activities, we invest in research and development in novel fields of hardware, sensors, vision, navigation, manipulation, communication and machine intelligence. In the future, we see the use of robots becoming even broader, always with the intention of supporting our personnel and facilitating CERN's fundamental research initiatives. This talk will present our development and use cases to date, and introduce the research areas we are focusing on.
While the manufacturing industry is strongly engaged in robotization, the construction field is still facing important scientific and technical challenges in this area. Indeed, this sector requires that robots work in large spaces, in accurate ways, on very varied activities where know-how must be adapted to complex environments. Therefore, we present several industrial studies that Nantes University (LS2N/CAPACITES) conducted in the robotization of activities such as tunnel boring machines, our current projects in the field of human-machine interaction, as well as the use of robotics in large spaces including the TIRREX project (Technological Infrastructure for Robotics Research of Excellence) aimed at developing new platforms in robotics.
The most relevant challenges of telerobotics technologies for the coming years are precise manipulation in semi-structured environments, high levels of tightening torque, and reduced execution time. Also, an iterative design of remote handling processes is necessary to comply with maintenance requirements properly. Other aspects to consider are operator training and robot recovery strategies, among others. In this talk, an overview of the challenges for remote handling and human-robot-interface is presented, with the focus on future developments and technologies.
The design of the interaction region of the positron-electron future circular collider must comply with various important constraints, imposed by high beam energy, high luminosity, need for polarization, and crossing scheme. An overview of the MDI design will be presented with a picture of the recent updates in the layout and ongoing studies. The status of the MDI activity will be summarised with goals and milestones for the feasibility study with a focus on those for the mid-term review.
This presentation is about the modelling process for vibrations estimations used at LAPP (Annecy's particle physics laboratory) for the FCC project. The main goal of this work is to be able to predict the magnets displacements knowing only the ground displacements. The presentation explains the connection between mechanical calculations and optics studies. It also describes the different steps of the process: modal analysis, extraction of the state space matrices, calculation of the displacement etc...
The precise alignment and monitoring of the FCC-ee MDI is mandatory in order to reach the designed luminosity. Though, the extremely elegant but also complex MDI design raises some tough challenges.
This presentation will underline the different challenges and explain why they represent difficulties for the design of an alignment and monitoring system. Subjects such as design, technology, sensors and tolerances will be covered. Finally, some solutions, ideas and strategies for the alignment and monitoring system for the FCC-ee MDI will be proposed.
The FCC-ee will be the largest accelerator ever built with kilometers of different accelerator devices. The identification of the main loads is crucial for designing the electricity infrastructure and for evaluating its energy consumption. An update of the FCC power demand is ongoing with the evaluation of its annual energy consumption depending on the machine configurations. The next step is to identify how energy consumption can be reduced, by design and optimization of equipment and systems, and by optimization of the operation mode of the accelerators and their infrastructures. The goal is to identify where the effort needs to be focused to reduce the environmental impact of the project.
The electrical infrastructure for the Future Circular Collider will be composed by a multi-layer transmission and distribution network covering all the power needs of the accelerator.
The study for the network considers as main inputs the known users’ requirements and the target load figures of FCC-ee, the power availability of the electrical grid of the surrounding area and its long-term evolution roadmap; furthermore, the study aims to determine the minimum set of features for the operability, reliability and maintainability of the network.
Starting from the baseline presented in the CDR of 2018, the network has now been updated on the new layout of the machine and on the latest users’ requirements, and the technical solution under development foresees a high voltage transmission level and a medium and low voltage distribution level.
The high voltage level is conceived to be fed by three connections to the French grid (RTE). The connection points have been selected based on a preliminary check on the availability of RTE to provide the required power, on the total load profile per point, and on achieving a balance and a symmetry in the internal transmission, that will route cables in the accelerator tunnel connecting all the eight points. The analysis will also identify the best possible topology to allow the evolution to FCC-hh.
The distribution level dispatches the power from the transmission grid to the end users at medium and low voltage. The baseline, as already presented in the CDR, uses conventional AC schemes. It will be further developed once the study of the transmission network will be finalized and the users’ requirements more detailed. Furthermore, emerging new technologies based on DC schemes are under study and could provide new options to improve the power quality and efficiency of the electrical distribution.
The aim of the presentation for this FCC week is to provide an update on the status of the studies mainly focused on the high voltage transmission network development and on the setup proposed for the connection to RTE grid.
The eight point configuration of the FCC together with the more precise definition of the RF areas are relevant input which modifies important factors of the cooling and ventilation baseline design. This presentation will describe the main challenges and present the current CV baseline parameters. It will also analyse the cooling infrastructure modification needed to pass from FCC-ee to FCC-hh highlighting in particular the primary cooling changes. The presentation will also show the planning through the phase 2 studies.
The beam parameters of FCC-ee with its high-intensity beams and large dynamic range lead to exceptional requirements for beam instrumentation devices. For high energy lepton machines, the detection of synchrotron radiation for the measurement of bunch length has been common practice in the past. However, given the exceptional size of FCC-ee, extracting synchrotron light comes with technical challenges and restrictions. Therefore, we propose the usage of Cherenkov Diffraction Radiation (ChDR) as an alternative radiation source for sampling the longitudinal profile of FCC-ee bunches. In this talk, the most recent simulation results for the utilization of ChDR are shown, which include different analytical as well as numerical studies. We will also present plans for experimental studies on coherent and incoherent ChDR.
Currently a semi-passive beam dilution system is foreseen for the FCC-ee beam dumping system. This system utilizes passive beam diluters (spoilers) made from carbon-based materials. To test the performance of these spoilers, an experiment was carried out in November 2021 at CERNs HiRadMat Facility with scaled prototypes of the proposed spoiler design. By using special beam optics to mimic the extremely flat beam of the FCC-ee, as well as pre-targets to increase the energy deposition, it was possible to create similar mechanical stress fields as expected for FCC-ee operation. To be able to compare the induced surface stresses, live instrumentation of the out-of-plane velocity directly at the beam impact point has been carried out, using a laser doppler vibrometer.
The construction of a mock-up of an arc half-cell of the FCC e+e- collider and booster is proposed, with the goal investigate the aspects related to integration, assembly, transport and maintenance of its components. As a first step, in the next months, it is necessary to develop an optimum overall integration solution for the arc, taking into account all the abovementioned constraints on top of the machine performance. The objective for the first phase of the project is to produce a 3D/2D model of the arc, as well as a summary report including the reasons for the technical choices, to be used as a specification for the successive detailed design and construction of the half-cell mock-up.
A status update on the beam induced backgrounds studies in the FCC-ee MDI region is presented. Currently under study are the optimisation of the Synchrotron Radiation (SR) shieldings, and background in the detector caused by Incoherent Pair Production (ICP) and beam particles lost during tracking. The turnkey software Key4HEP is being used to track the background particles in the CLD detector in order to estimate the related hit densities. The beamstrahlung radiation produced at the IP has been characterised using GuineaPig in order to estimate the total power and the region where this radiation will hit the beam pipe.
The interaction region for the Future Circular Collider FCC-ee at 182.5 GeV is a sensitive section of the accelerator. The synchrotron radiation produced in the surrounding environmnent of the detector can result in background or damages to the hardware. The studies will present the deposited synchrotron radiation power from the magnetic elements included in the interaction region as well as the collimation strategies to mitigate the flux of photons.
Logistic of equipment and personnel is a major aspect during the assembly, installation but also operation of the future FCC. The transport and handling tools and means need to be studied in details, in an early phase, in order to control the associated costs as well as the duration of interventions.
The presentation will give an overview on the requirements for the special vehicles dedicated to the underground transportation and handling of magnets for FCC-ee machine, transportation of people and their tooling, mainly focusing on dimensions, performance and boundaries conditions.
Fraunhofer-IML has analyzed several logistics and handling aspects during the FCC Conceptual Design phase. As part of the feasibility study phase, the key accelerator parameters are being redefined and the existing basic concepts for logistics and material handling vehicles will thus be reviewed and developed in more detail. Within this phase, the studies will focus on three main areas of research and development: 1. Vehicle concept for the underground transportation and handling of magnets; 2. Vehicle concept for the underground transportation of people; 3. Logistics concept for storage, assembly and testing of magnets including cycle times of different set-ups. The presentation will describe the procedure for concept development in the aforementioned three areas and will provide first thoughts on transport options.
The Future Circular Collider is an accelerator research facility with unprecedented dimensions, located in a tunnel with 91 km circumference in a depth of around 200 metres underground. Safety hazards such as ionising radiation, fire, cryogenic gas releases, and oxygen deficiency paired with complicated emergency access and evacuation require solutions for risk mitigation already embedded in the facility’s design.
In the Conceptual Design Report, a few solutions were studied, while the Feasibility Study must show that they can be implemented in the underground infrastructure. The FCC Safety Working Group concentrates on fire safety, extending the fire safety concept presented in the CDR to service caverns and experiments and developing a workable solution for the compartmentalisation. This is also a key element for cryogenics safety in FCC-ee and FCC-hh, where compartment walls and extraction systems will be used to protect personnel from oxygen deficiency. The validity of this approach shall be demonstrated with analytic and numerical models, which remain to be partly developed. Radiation protection studies will focus on the effects of ionising radiation in an e$^-$/e$^+$ collider, both in the facility and in the environment, while making sure that the safety requirements for FCC-hh can be equally met. Finally, proposals for beam- and access safety will be elaborated, drawing on the experience with LHC and its injectors. This element includes also the use of remotely controlled or autonomous equipment for transport and well-defined technical tasks with the aim to keep personnel out of the potentially hazardous accelerator environment.
The work will be underpinned by a hazard register with “standard best practice” mitigation measures and will be summarised in a FCC Feasibility Study Safety Report.
The FCC underground infrastructure presents important challenges in terms of human intervention and evacuation in case of an emergency. Both, time and distances required to get to or evacuate areas far from access shafts are large. Employing robots can mitigate the risk linked to this infrastructure.
Thus, usage of robots are an inherent part of the global FCC safety concept. Their main justification is twofold; on one hand, usage of robots for monitoring and maintenance purposes limit human presence underground and, thus, improve the life safety goal by reducing risk exposure. On the other hand, robots can be deployed with fast response time and, therefore, provide unique and valuable data to inform and support decision makers, start a first intervention and later support a human intervention in case of incident or emergency. This last point is of paramount importance as the concept of human intervention, including techniques, firefighting, rescue materials, and logistics, must be shaped differently w.r.t current LHC approach due to dramatic increase of distance from any fire station on surface to the underground areas and the consequent response times.
This talk will highlight the necessity of this technology as well as the added value of embedding robots (and their particular requirements) into the FCC safety design in the very early stage. The talk will focus on current CERN and external examples of robot support for maintenance and emergency situations. It will showcase up-to-date approaches and CERN advancements to prepare this technology to support such a safety objective while highlighting the challenges and key features of their integration into the FCC.
Global fits to electroweak precision data, comparing the measured values of different quantities with the SM predictions, provide important checks of the SM consistency and sensitivity to beyond-the-SM (BSM) effects. The two most sensitive determinations of $\sin^2 \theta_{\rm eff}^{\rm lep}$, from the LEP measurement of $A_{0,b}^{FB}$ and the SLD measurement of $A_\ell$,
are in $\sim$3 $\sigma$ tension with each other, the largest deviation in global electroweak fits.
In this contribution we discuss the possibility to probe at the FCC-ee the interactions between the $Z$ boson and the bottom quark through a competitive determination of $A_{0,b}^{FB}$.
To this extent we aim to reproduce the measurement performed at LEP, exploiting the decay of a $Z$ boson in a bottom-quarks pair.
The definition of this asymmetry intrinsically requires some sensitivity to the charge of the bottom quark/antiquark in the final state, which represents one of the major challenges of this measurement. By means of a simplified Delphes-based simulation tuned to the IDEA detector at FCC, we plan to study the expected experimental b-jet charge identification performances using either constituent tracks information or exploiting the charge of a soft muon from $B$-hadron decays.
The successful identification of strange quark jets at the FCC-ee would enable the study of a multitude of largely unexplored processes, including the first ever study of Z->ss production, rare Higgs boson decays and the strange Yukawa coupling, CKM matrix elements via W decays, and BSM physics scenarios such as FCNCs. Due to the challenging nature of distinguishing these medium-mass quarks, strange tagging is a topic that has up to now received considerably less attention than its heavy flavour counterparts, or indeed gluon tagging. A multiclassifier neural network using a transformer-based architecture is coupled with secondary vertexing and a novel implementation of K short reconstruction at the FCC-ee to discriminate strange quark initiated jets. This poster presents a state-of-the-art strange quark tagger at the FCC-ee, with a focus on light quark discrimination at the Z pole.
Numerous studies and measurements planned at the FCC-ee rely on efficient and accurate jet flavour tagging algorithms, which in turn heavily rely on secondary vertex reconstruction as b and c jets contain long-lived hadrons that decay hundreds of microns from the collision point. At the same time, vertex reconstruction is also an important tool to test the performance of different vertex detector designs.
LCFIPlus is a flavour tagging framework developed for linear colliders that includes a vertexing module. Here, we present the incorporation of this vertexing module into the FCCAnalyses framework. The flexible and configurable implementation consists of reconstructing the primary, the secondary vertices, and longer-lived V0s, which have been adapted both for rejection and to identify V0s. We show the performance of the vertex finding module and present the potential refining techniques that can be incorporated.
GRAiNITE Studies
Presentation of a new type of sampling ECAL calorimeter. It is of the Shaslik type with WLS fibers, but instead of lead and scintillator plates, it uses a mixture of crystal scintillator grains and heavy liquid. According to Geant 4 studies, the finer sampling allows to reach a resolution < 2%/sqrt(E) A sample of ZnWO4 grains obtained by “spontaneous” flux method crystallisation has been obtained by ISMA Ukraine. Scintillation yield of the grains will be presented. A new method is proposed to correct for the e/h ratio and therefore the jet energy resolution of this ECAL part of a dual readout calorimeter, it uses the Pulse Shape Discrimination properties of crystal scintillator to evaluate the fraction of energy deposited by non relativistic particles, examples of such discrimination will be given.
The Higgs boson trilinear and quartic self-couplings are directly related to the shape of the Higgs potential; measuring them with precision is extremely important, as they provide invaluable information on the electroweak symmetry breaking and the electroweak phase transition.
\In this paper, we perform a detailed analysis of double Higgs boson production, through the gluon-gluon fusion process, in the most promising decay channels $b\bar{b} \gamma\gamma$, $b\bar{b} \tau\tau$, and $b\bar{b}b\bar{b}$ for several future colliders: the HL-LHC at 14 TeV and the FCC-hh at 100 TeV, assuming respectively 3 $ab^{-1}$ and 30 $ab^{-1}$ of integrated luminosity.\
In the HL-LHC scenario, we expect an upper limit on the di-Higgs cross section production of 0.76 at 95\% confidence level, corresponding to a significance of 2.8 $\sigma$.
In the FCC-hh scenario, depending on the assumed detector performance and systematic uncertainties, we expect that the Higgs self-coupling will be measured with a precision in the range 4.8-8.5\% at 95\% confidence level.\
A plethora of measurements at the FCC-ee crucially depend on efficient flavour tagging and precise flight distance measurements. To achieve this, the innermost piece of the FCC-ee detectors, the vertex detector, has to precisely locate the collision vertices, while adding only a minimal amount of material to the detector.
The proposed reduction of the beam pipe radius at the FCC-ee from 1.5 to 1 cm allows to move the first layer of the vertex detector closer to the interaction point, improving the impact parameter resolutions. In order not to get in the way of the beam pipe, the geometry of the vertex detector has to be adjusted however. This contribution presents the simulated performance of several vertex detector geometries in terms of impact parameter and vertex resolution and investigates the benefits of an extended forward coverage.
KKMCee version 5.0 Monte Carlo event generator is for lepton and quark pair production for the high energy electron-positron annihilation process. It is the most sophisticated event generator for such processes. Its entire source code is now re-written in the modern C++ language (to be included in the FCCee software soon). It reproduces all features of the older KKMC code in Fortran 77. However, a number of improvements in the Monte Carlo algorithm are also implemented. Most importantly, it is intended to be a starting point for the future improvements, which will be mandatory for the future high precision lepton collider projects. As in the older version, in addition to higher order QED corrections, it includes so-called $\alpha^{1.5}$ genuine weak corrections using a version of the classic DIZET library and polarized τ decays using TAUOLA program. Both DIZET and TAUOLA external libraries are still in Fortran 77. In addition, a HEPMC3 interface to other MC programs, like parton showers and detector simulation, replaces the older HepEvt interface. It is also instrumental in adding the additional photon final state emissions in τ decays using an external PHOTOS library rewritten in C.
Recent analyses on high-energy inclusive Higgs-boson rates in proton collisions via the gluon fusion channel, matched with the state of-the-art fixed-order N$^3$LO accuracy, have shown that the impact of high-energy resummation corrections reaches 10\% at the FCC nominal energies. This supports the statement that electroweak physics at 100 TeV is expected to receive relevant contributions from small-$x$ physics. In this talk we will present novel predictions for transverse-momentum and rapidity distributions sensitive the inclusive emission of a Higgs boson in association with a light-flavored jet in proton collisions, calculated within the NLL accuracy of the energy-logarithmic resummation. We will highlight how high-energy signals for this process are already present and visible at current LHC energies, and they become very important at FCC ones. We come out with the message that the improvement of fixed-order calculations on Higgs-sensitive QCD distributions is a core ingredient to reach the precision level of the description of observables relevant for the Higgs physics at the FCC.
In this work, we derive lower mass bounds on the $Z^\prime$ gauge boson based on the dilepton data from LHC with 13 TeV of center-of-mass energy, and forecast the sensitivity of the High-Luminosity-LHC with $L=3000 fb^{-1}$, the High-Energy LHC with $\sqrt{s}=27$~TeV, and also at the Future Circular Collider with $\sqrt{s}=100$~TeV. We take into account the presence of exotic and invisible decays of the $Z^\prime$ gauge boson to find a more conservative and robust limit, different from previous studies. We investigate the impact of these new decays channels for several benchmark models in the scope of two different 3-3-1 models. We found that in the most constraining cases, LHC with $139fb^{-1}$ can impose $m_{Z^{\prime}}>4$~TeV. Moreover, we forecast HL-LHC, HE-LHC, and FCC bounds that yield $m_{Z^{\prime}}>5.8$~ TeV, $m_{Z^{\prime}}>9.9$~TeV, and $m_{Z^{\prime}}> 27$~TeV, respectively. Lastly, put our findings into perspective with dark matter searches to show the region of parameter space where a dark matter candidate with the right relic density is possible.
The cool-down and cryostating of the FCC superconducting magnets requires transport and distribution of large quantities of cryogens over distance up to 10 km. It significantly exceeds the experience gained from the existing Big Science helium cryogenic systems. To limit the pressure drop and the distribution header diameters, cryogens could be distributed at high pressure up to 50 bar. Such a choice would result in significant thermo-mechanical challenges, which must be addressed when designing the cryogenic distribution system (CDS) and the superconducting magnet cryostats. The paper presents possible CDS design solutions optimized with entropy minimization method analysis. The advantages of stainless steel replacement with invar are discussed. The FCC cryogenic system reliability issues are discussed.
The Karlsruhe Research Accelerator (KARA) at KIT was the first synchrotron to successfully implement near-field electro-optical (EO) beam diagnostics to conduct turn-by-turn bunch profile measurements. In the scope of the FCC Innovation Study (FCCIS), this beam diagnostics concept is under investigation as a tool for the future electron-positron collider FCC-ee to measure center-of-charge and longitudinal profile of the electron bunches.
This contribution provides an overview on the opportunities and challenges of EO beam diagnostics for FCC-ee based on simulations and experiences at KARA.
The design of future lepton colliders, which would push the beam intensity frontier significatively forward with respect to the current state of the art, paves the way to novel technological challenges. In particular, the need for very high positron yield in the linear (ILC and CLIC) or circular (FCC-ee, CEPC) colliders requires that innovative approaches to the positron production are considered. It is particularly promising to exploit the enhancement of the electromagnetic processes (namely, bremsstrahlung and pair production) obtained in the interactions of $e^{\pm}$ and photons with oriented crystalline matter at the multi-GeV scale to develop a next-generation positron source; in general, the latter would feature lower heating- and irradiation-related damage as compared to the conventional setup, which is based on amorphous matter. Several configurations are feasible, which would exploit one or multiple targets made of high-$Z$ materials such as tungsten. Measurements have been made with electrons impinging on single-crystal tungsten samples at the DESY T21 and CERN H2 beamlines, to extensively characterise these effects at a few GeV and at $20$~GeV respectively.
High temperature superconductors-coated conductors (HTS-CC) with its significantly low surface impedance at low temperature (below superconducting critical temperature Tc) are being considered a good alternative to Cu as coatings for the beam screen of the hadron-hadron future circular collider (FCC-hh). In particular, rare-earth barium cuprates (REBCO-CC) are excellent candidates considering its commercial availability in km lengths and appropriate widths. Several studies have been performed to study its surface impedance as a function of temperature, ac magnetic field that mimics the image current, as well as under the influence of an external dc magnetic field. Its frequency dependence at frequencies of interest for the FCC-hh, however, has yet to be studied. We will present the frequency dependence of various available REBCO-CCs in the frequency range between 6 and 30 GHz, as a function of temperature. The data allows the determination of the depinning frequency as well as of the flux creep factor as well as will allow to estimate beam impedance as a function of frequency.
Within the framework of the Future Circular Collider Feasibility Study, the design of the electron-positron collider FCC-ee is optimised. Polarized low intensity pilot bunches are foreseen at the first energy stages to determine the beam energy, and thus sufficient level of polarization must be achieved which can be limited by alignment and optics errors. Additionally, strong synchrotron radiation damping at the highest beam energy and its impact on the beam dynamics will demand optimized beam measurements to control the optics at the desired level. Various techniques to measure the optics in the FCC-ee are explored, including the orbit response matrix approach and turn-by-turn measurements.
The ability to know the beam energy extremely precisely is a fundamental asset for any storage ring lepton collider such as the FCC-ee. Since the energy is fundamentally related to the spin tune, measuring the spin precession frequency determines the energy; the method requires that the beams be polarized. We present here first simulations for a simplified lepton storage ring with 100 m circumference, which allows to understand in depth this phenomenon and address some of the possible systematic uncertainties. Furthermore, we discuss two methods for measuring the spin tune, namely by either a Fast Fourier Transformation or by a more direct technique which allows to measure the spin tune from only a few turns. The second option is then used to obtain an estimate of the beam energy over numerous revolutions.
Over the years, it has been observed for cavities in operation in accelerators, a continuous degradation of their performance with the appearance or reinforcement of the parasitic field emission phenomenon. This phenomenon, caused by surface pollution promoting the emission and acceleration of electrons by electromagnetic fields, causes the generation of ionizing X radiations. This poses safety problems but also increases the thermal load in the liquid helium bath. This generally involves dismantling the accelerator cryomodule in order to reprocess the accelerating cavities. In recent years, a very promising treatment, applied to the SNS accelerator, for example, allowed to avoid the complete dismantling of faulty cryomodules. This involves generating a reactive plasma by RF excitation of the fundamental mode of the cavity using the RF system already in place. This "in-situ" treatment proves to be very effective in reducing the phenomenon of field emission. In order to reproduce state-of-the-art and optimize the plasma cleaning procedure for QWR cavities, we developed a unique test-bench operating in two modes: 1) sample cleaning, 2) cavity cleaning. Sample mode gives possibility to optimize the efficiency of cleaning depending on the gas composition, pressure, flow, etc… . Cavity mode is under investigation and will allow to characterize the plasma cleaning homogeneity depending on several parameters like RF power, frequency and gas mixture.
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The escalating interest of the future lepton colliders with high luminosity, draws the attention to the crucial role of the positron sources. One of these colliders is the FCC-ee. Two main positron production schemes (Conventional and Hybrid) are considered for the FCC-ee, will be discussed briefly here. The work is in progress for the development of positron generation and tracking model until the Damping Ring. The model starts with the production of positrons and target studies in GEANT4. After that, the generated positrons are tracked through the capture section composed of the matching device and several accelerating structures to accelerate the positrons until the energy of the Damping Ring. This part is implemented by using the code developed at CERN called RF-track. Eventually, the preliminary results for benchmarking of the FCC-ee positron source simulation model with the existed SuperKEKB positron source will be discussed.
La physique des particules explore l’infiniment petit et permet d’élucider l’évolution de l’Univers depuis ses origines. Bien que la compréhension actuelle, résumé « dans le modèle standard », donne une description avec une précision époustouflante des phénomènes observés, des questions restent ouvertes : le rôle du boson de Higgs, l’asymétrie matière antimatière, la compréhension de la matière noire. Nous évoquerons ces questions en précisant quel élément de réponse le projet FCC peut y apporter.
capables de résister à des taux d’irradiation sans précédant. Elles devront aussi traiter des flux de données gigantesques, dont il faudra maîtriser la complexité pour extraire des signaux de physique bien dissimulés ou extrêmement rares.
Nous évoquerons les nouveaux paradigmes proposés pour atteindre ces objectifs. Quelques exemples de développements techniques nécessaires, depuis la détection des particules jusqu'à l’obtention d’un résultat de physique, nous montrerons comment ils s’inscrivent dans la problématique de nombreuses autres disciplines scientifiques.
Le futur collisionneur circulaire (FCC) est conçu pour être la prochaine génération de collisionneur de particules à haute performance, qui prendra le relais du LHC, lorsque la phase de haute luminosité (HL-LHC) de cette machine arrivera à son terme, vers 2040.
La mission du FCC sera de repousser les frontières d'énergie et d'intensité des collisionneurs de particules, dans le but d'atteindre des énergies de collision de 100 TeV dans un tunnel de 100 km, à la recherche d'une nouvelle physique. Une collaboration internationale de plus de 150 universités, instituts et partenaires industriels du monde entier développe différentes possibilités pour ces collisionneurs circulaires, en se concentrant sur l'exploration des collisions électron-positron et proton-proton.
Nous montrerons les nombreux défis technologiques qui doivent être résolus, ainsi que les retombées que l'on peut en attendre dans la société et l'industrie européennes.
Nous pouvons déjà citer le défi de la construction d'un tunnel de 100 km qui devrait passer sous le lac Léman en Suisse, mais aussi en France, en Haute-Savoie, et qui devra intégrer la gestion des matériaux d'excavation et son impact environnemental. Mais aussi les défis du développement de nouveaux systèmes d'accélération et de nouveaux aimants supraconducteurs avec un champ magnétique double de celui du LHC. Enfin, nous aborderons le défi énergétique d'un tel collisionneur, qui devra aussi prendre en compte la réduction de son empreinte écologique globale.