Significant progress has been made in the last year in advancing the critical current density of RRP® and PIT Nb3Sn strand by more efficient use of the non-Cu volume used to make the Nb3Sn. For RRP® we show how changing the intermediate heat treatment step to better mix the Cu and Sn and avoid unnecessary Nb dissolution can enable critical current density values above 2900 A/mm2 (12 T, 4.2 K)...
The FCC-ee collider is designed to provide extreme precision measurements of electro-weak parameters running at various center of mass energies: Z pole, WW pair, Z plus Higgs boson and top quark pair production. This machine is expected to deliver an unprecedented luminosity, more than three orders of magnitude of that achieved by LEP at comparable energy, with beam features much different...
We present a study on performance limitations and effects on pinning force scaling behavior of A-15 phase inhomogeneity, in particular Sn concentration gradients, in commercial PIT and RRP Nb3Sn wires. Our results were obtained from SQUID magnetometry, scanning Hall probe microscopy, and numerical simulations. Our key findings are that even small radial Sn concentration gradients inside...
The FCC-hh (Future Hadron-Hadron Circular Collider) is one of the options considered for the next generation accelerator in high-energy physics as recommended by the European Strategy Group. In this overview we will describe the status and the evolution of the design of optics integration of FCC-hh, focusing on design of the arcs, alternatives, and tuning procedures.
The technical design concept for the FCC-hh cryogenic beam vacuum system was developed based on the constraints that emerge from the arc design requirements. Within this framework, a BEam Screen Testbench Experiment (BESTEX) measurement setup was designed with the goal of determining the photodesorption yield, synchrotron radiation heat loads and photo electron generation inside 3 different...
Dual-Readout calorimetry is a technique that allows to overcome the non- compensation problem (one of the main limiting factor for the hadronic energy resolution) by the simultaneous measurement of Cherenkov and scintillation light, produced by the shower particles. Thanks to the expected good energy resolution and the excellent particle identification capability, the Dual-Readout fiber...
The design study for the future circular collider (FCC) includes an electron-positron collider with beam energies ranging from 45.6 to 182.5 GeV in order to study the properties of the Z, W and H bosons and the top quark with high precision. In order to accelerate the particles to the required energy, an RF system is needed to provide the accelerating voltage for the four machine setups....
"The FCC-hh (Future Hadron-Hadron Circular Collider) is one of the options considered for the next generation accelerator in high-energy physics as recommended by the European Strategy Group, and the natural evolution of existing LHC. The evaluation of the various magnets mechanical error and field error tolerances in the arc sections of FCC-hh, as well as an estimation of the correctors...
In FCC-hh one of the most challenging issue will be the control of all possible instabilities that could occur. In order to do so, all vacuum vessel inner surfaces need to be characterised in great details. Among others properties, their Secondary Electron Yield (SEY), Photo Yield (PY), Reflectivity (R) and their capability to adsorb residual gas molecules and maintain them absorbed during...
The remarkably efficient potential operation of the 100 km FCC as a heavy-ion collider was demonstrated right at the inception of the FCC study. Luminosity projections have risen in recent years in line with the higher intensity beams of lead nuclei now being collided in the LHC. Close contact with the physics working group has been maintained to evaluate the interest of heavy Pb-Pb,...
This talk will give an overview of the developments and the achievements of the Experimental Insertions of FCC-hh.
FCC-ee is designed to operate at energies from 45.6 up to 182.5 GeV with unprecedented luminosity. This brings some challenges in controlling the emission of synchrotron radiation (SR) photons. A scheme of tungsten shielding has been developed to minimize this effect on the detector backgrounds.
Superconducting accelerating cavities are the technology of choice for many modern and future particle accelerators. Increasing their efficiency is therefore crucial to minimize the power consumption during their operation and therefore significantly cut the cost and enabling the realization of more powerful machines.
The efficiency of niobium superconducting RF cavities can be maximized in...
HTS coatings have recently been proposed for beam impedance mitigation in the FCC beam screen. One of the candidate materials that can still work under the exceptional conditions of 50K, 16T, above 10^5 A/cm^2 is the Tl cuprate TlSr2Ca2Cu3Ox (Tl-1223) that with a Tc of about 120 K, very high Hc2 and Hirr, and moderate anisotropy is a promising material for such application. This possibility is...
Niobium coated copper accelerating cavities have demonstrated their strong potential in accelerators such as LEP, LHC and HIE-ISOLDE and could become a technology of choice for such a machine as the FCC.
On the way of further improving thin-film coated copper cavities performances one proposes to substitute niobium by a superconductor that could lead to a higher quality factor as well as a...
Dynamic aperture studies have been performed on the FCC-hh lattice at different energies to study the stability of the beam and the effect of different errors. Initial studies for the FCC-hh lattice at collision energy with errors on the triplet showed a very low dynamic aperture, most likely affected by the large integrated quadrupole length of the quadrupoles and the high beta function at...
Non-evaporable getter coating of vacuum chamber of particle accelerators was invented approximately 20 year ago by C. Benvenuti at CERN. This technology have already demonstrated its benefits an many machines: ESRF, Elettra, Diamond, Soleil, LHC, MAX-IV, etc. The NEG coatings are very effective vacuum solution, the UHV/XHV conditions could be reached in fully coated vacuum chamber of particle...
The possibility to create the reliable and solid magnet system of FCC project working with reasonable margin is defined by the development of the internal tin Nb3Sn wires with combination of contradicting properties including the non-Cu critical current density larger than 3000 A/mm2 (12 T&4.2 K) altogether with low effective diameters of the Nb3Sn filaments (down to 20 µm) and high RRR of...
Superconducting wire having high critical current density(Jc) under high magnetic field(16T) is required for fabrication of dipole magnet for FCC project. Currently, Nb3Sn wire is the most promising as a superconducting wire satisfying such a requirement, but in order to reduce amount and manufacturing cost, improvement of Jc is necessary. For this purpose, a preliminary development program of...
A key challenge for the next accelerators is the cost reduction. Bulk niobium cavities performances are closer to their theoretical limits and an alternative technology is mandatory. Niobium thin film copper cavities are the most explored solution, but the Q-slope problem, characteristic of these resonators, limits the applications where high accelerating fields are requested.
In this work an...
"Making HTS conductors constrained by the poor superconducting properties of grain boundaries suitable for high field magnet and especially for accelerator use has been a 30 year odyssey. At the NHMFL we have placed particular emphasis on Bi-2212 because of its round-wire, multifilament architecture. Over the last several years we have shown that it can be processed into high Jc forms that...
The proposed Future Circular Collider at CERN should reach a collision energy of 100 TeV thanks to a four times larger radius and double the magnetic field of the LHC. The latter requirement necessitates the development of superconducting materials/conductors with increased operating field.
Whilst most efforts are focused on Nb3Sn wires, this is an opportunity to assess the potential for high...
The future circular collider (FCC-hh) with proton beam energy of 50 TeV and total stored energy of 8.4 GJ requires a collimation system with very high cleaning efficiency to prevent quenches of the superconducting magnets. Collimation performance can be strongly affected by collimator imperfections such as gap errors, jaws deformations, tilt and misalignments. Tracking simulations in SixTrack...
Ternary Molybdenum Chalcogenide (TMC) superconductors were intensely studied until the mid 1990s. Although TMC's are low temperature superconductors (Tc ≤ 15 K), they show upper critical fields up to 60 T. R&D for TMC superconducting wires were carried out by academia and industry, e.g. Alstom (F), Mitsubishi (J) and Plansee (A). Recently it was found that the $/kg price and the $/kAm...
In the framework of the FCC study, niobium-coated copper cavities are considered to operate at 400 MHz. Electrohydraulic forming (EHF) is a potential alternative to conventional shaping methods of copper half cells, through which geometrical precision, a good repeatability and a reduced spring back can be achieved.
Material characterisation by hardness measurements, Electron Backscatter...
The collimation system intercepts the beam halo by absorbing part of the induced shower and retaining the rest in the warm segment of the ring in order to protect the downstream superconducting (SC) magnets from quenching. The FCC-hh betatron cleaning insertion region (2.7 km long) features primary collimators (TCP), secondary collimators (TCSG) and active absorbers (TCLA), whose design have...
The Nb3Sn dipole design for the hadron machine option of the Future Circular Colliders enters in an intense and long R&D phase. As a result, more realistic dipole field quality evaluations are available for beam dynamics studies. In this paper we discuss the impact of the main dipole field quality on the first and second order design of the hadron machine and on its dynamic aperture.
Recently, nitrogen doping (N-doping) technology has been proved to increase Q value of superconducting cavity obviously, which lowers the BCS resistance of Nb. After N-doping, Q of 9-cell 1.3 GHz cavity can be increased to 3E10 at Eacc = 16 MV/m, while 1.5*1010 without N-doping. Since 2013, there have been over 60 cavities nitrogen doped at FNAL, JLAB and Cornell. The Circular Electron...
The FCC-ee experiments will collect an unprecedented amount of data at sqrt s = 240 and 360 GeV. The Higgs bosons are produced in very large numbers, either in association with a Z boson or through W-boson fusion, and are detected in several decay channels. The production yields are combined to measure the Higgs couplings and invisible width with sub-percent precision. The precision obtained...
"The design of the FCC-hh extraction systems is driven by the challenge to safely extract the 50 TeV proton beam. The new baseline for the beam dump system design foresees a fast single plane extraction realized by a highly segmented kicker system and a combination of SuShi (Superconducting Shield) and superconducting Cosine-Theta septa. In the dumpline a focusing structure is included to...
The Standard Model of particle physics is still lacking an understanding of the generation and nature of neutrino masses. A favorite theoretical scenario (the see-saw mechanism) is that both Dirac and Majorana mass terms are present, leading to the existence of heavy partners of the light neutrinos, presumably massive and nearly sterile. These heavy neutral leptons (HNLs) can be searched for...
The FCC proton beams pose a severe challenge for the robustness of the beam dump and respective protection devices. Depending on the local beta-function, already a single 50 TeV bunch could induce damage in typical absorber materials currently employed in the LHC machine (e.g. Graphite or carbon composites). In order to safely absorb the FCC beams in a LHC-like dump or beam-intercepting...
By collecting tens of ab^-1 integrated luminosity in the range of center-of-mass energies sqrt(s) =90--350 GeV, the FCC-ee offers unique physics opportunities for precise measurements of QCD phenomena and of photon-photon collisions through, literally, billions of hadronic final states as well as unprecedented large fluxes of quasireal photons radiated from the e+e- beams. We succinctly...
The Future Circular Collider (FCC-hh) will have a beam screen with T between 20 and 60 K. Electron cloud mitigation will be critical for the FCC-hh and it has been specified that the wall material needs to have a Secondary Electron Yield (SEY) < 1. Since the LASE surfaces with SEY<1 are the baseline electron cloud mitigation technique, it is critically important to study the behaviour of the...
The sizes of the beta functions in the final focus triplet of a synchrotron collider have a great impact on the chromaticity and dynamic aperture of the machine. These beta functions are proportional to the square of the length of the final drift so it is desirable to keep it as short as possible whilst leaving enough room for the experiment. In the latest design of the FCC-hh this drift was...
One of the critical parameters of the high Jc internal tin Nb3Sn strands designated for the high field magnets of the FCC project is essentially high RRR value exceeding 150. In this work Oxygen free high-purity copper with RRR>400 was used for production of internal tin Nb3Sn wires of 0,7 and 1 mm in dia with 37 sub-elements in distributed diffusion Nb-barriers. Final reactions from 25 to...
One of the biggest challenges in the design of the FCC-hh is the collimation system. From LHC experience it is known that a collimation system optimized for proton cleaning has a significantly reduced efficiency for heavy ions. The study presented in this contribution evaluates the betatron-collimation efficiency for the heavy-ion operation with lead nuclei at a beam energy of 50 Z TeV in the...
An analytical electron positron circular collider optimized design method has been developed with carb-waist collision and CEPC parameters for Higgs, W and Z have been given by this method. For the lattice of CEPC collider ring, the combined magnet (dipole+sextupole)scheme has been developed to reduced the power consumption of the stand-alone sextupoles. The power consumption of the original...
This contribution presents our collider availability model used in FCC study. The model represents failure logics, operations and calculates the integrated luminosity productions, which is one of the key performance indicator for colliders. The operation phases are essential part of the collider model, as several steps are required to prepare the collider for collisions. This means that the...
We probe the effects of dimension-eight operators giving rise to anomalous neutral triple gauge boson interactions of Z𝛾𝛾 and Z𝛾Z vertices in l-l+𝛾 production (pp→ l-l+𝛾) at 100 TeV centre of mass energy of future circular hadron collider, namely FCC-hh. The analysis is performed on transverse momentum of photon and angular distribution of charged lepton in the final state including a...
Superconducting niobium-tin (Nb3Sn) wires have become a key technology for the development of next generation accelerator magnets. These conductors can be described by their high critical current density but also by their remarkable strain-dependent behavior. In presence of mechanical loads, the superconducting lattice is distorted resulting usually in a reversible decrease of the critical...
In FCC-hh, one of the most challenging issue will be to limit all possible instabilities that could occur. Expected instabilities are mainly related to the large number of photons and photoelectrons present in the vacuum beam-pipe. Photons and photoelectrons will induce gas desorption and single beam instabilities, whereas at LHC instabilities are dominated by e-cloud formation. It is,...
This work presents a study of Higgs boson production in jets and missing energy final states at the FCC-ee collider. In particular, we explore how different detector parameters and the beam strahlung affect the sensitivity of Higgs boson coupling measurements.
In this paper we aim to reveal methods that can decrease the time spent on the mechanical elements development increasing the efficiency of the process. The challenge in this scheme is the optimization of a large number and variety of components in the ITER diagnostic system. During our work we compared the engineering requirements with the specific requirements of a fusion power plant.
Our...
The stress-strain behaviour of the Nb3Sn conductor blocks of the superconducting coils for the Future Circular Collider (FCC) magnets need to be known in order to predict the stress state distribution in the coils during magnet assembly and operation. The stress-strain behaviour of reacted and impregnated 11 T Rutherford cable stacks has been determined using a dedicated set-up with an...
FCC-ee special features for the high energy running, description of top precision measurements at threshold and above and implications for new physics.
In the framework of the EuCARD-2 WP-10 program, CERN has produced two sets of High Temperature Superconductor (HTS) insert-magnets wound with ReBCO-Roebel cable, named FeaTHeR-M2 and FeaTHeR-M0. FeaTHeR-M2 is an aligned block magnet designed to generate 5 T in a 40 mm aperture, whereas FeaTHeR-M0 are sub-scale planar racetrack coils designed to test fabrication techniques and gain experience...
The beam-beam interaction is one of the most severe limitations on the performance of circular colliders, as it is an unavoidable strong nonlinear effect. As one aspires for greater luminosity in future colliders, one will simultaneously achieve stronger beam-beam interactions. We study the limitations caused by strong incoherent head-on beam-beam interactions, using a new GPU-based code...
The baseline design of the FCC-hh beam screen is based on an octagonal shaped stainless steel tube coated in its interior with copper. The surface impedance of the beam screen has a strong impact on the beam stability. In the foreseen operating temperature range between 40 K and 60 K the intended coating might not guarantee an impedance sufficiently low for a stable beam. This motivates the...
Dual-Readout calorimetry is a relatively new calorimetric technique able to overcome the non-compensation problem by means of two independent scintillation and Cherenkov light signal detections. Scintillating photons provide a signal proportional to the whole energy deposition in the calorimeter while Cherenkov photons emitted in clear fibers provide a signal almost exclusively related to the...
CEPC is a 100 km circular electron-positron collider operating at 90-240 GeV center-of-mass energy of Z-pole, WW pair production threshold, and Higgs resonance. CEPC and its successor SPPC, a 100 TeV center-of-mass super proton-proton collider, will ensure the elementary particle physics a vibrant field for decades to come. To reduce the overall cost, partial double ring scheme was proposed as...
At high proton-beam energies, beam-induced synchrotron radiation is an important source of
heating, of beam-related vacuum pressure increase, and of primary photoelectrons, which can give
rise to an electron cloud. We present the synchrotron radiation map computed by Synrad3D for the latest shape of the FCC-hh vacuum chamber with a sawtooth surface instead of a wedge.
In the framework of the FCC study, the Nb3Sn technology plays a crucial role for high-field superconducting magnets. The new generation Nb3Sn cable greatly contributes to bring the magnetic field produced by the superconducting dipole magnets to the 16 T level; nevertheless, its mechanical properties are unknown making it difficult to predict the mechanical behaviour of the magnet structure....
A part of the FCC-hh design study explores different superconducting materials, which could be suitable to function as a coating on the beam screen, held at 50 K. Such a superconducting coating should be able to carry the beam image currents and lower the beam impedance in order to guarantee a high beam stability margin. Our study focuses on the still technologically unexploited thallium-based...
We present results of microstructural examinations of grain size distribution, grain geometry, compositional gradients and local texture performed on Nb3Sn wires of various manufacturing techniques. Measurements were conducted using high-resolution TEM (transmission electron microscopy), EDX (energy-dispersive X-ray spectroscopy) and TKD (transmission Kikuchi diffraction). Findings include...
Minimising the thickness of TiZrV non-evaporable getter (NEG) coatings is mandatory for increasing single-bunch instability thresholds in the proposed FCC-ee high luminosity lepton collider. After thermal activation the NEG surface is depleted of its O content and the total electron yield (TEY) decreases to values close to 1.1. The effect of reducing the thickness of NEG coatings on activation...
The current cryogenic design for the FCC-hh consist of a helium cycle with pre-cooling by the Nelium cycle. Both have their own set of compressors and heat exchangers. The potential of combination of these two distinct cycles with a reduced number of components is investigated. Using efficient turbo compressors requires a mixed refrigerant with a heavier ballast gas to achieve reasonable...
The volume of data produced at the Large Hadron Collider (LHC) is immense and represent a considerable processing challenge. Moreover the LHC and future hadronic colliders are the most demanding environments, with respect to ultra-low latencies, ultra-high data rate, reliable indoor coverage and harsh radiation environment, in the world.
Any technology meeting the above conditions will have to...
Non-evaporable getter coating of vacuum chamber of particle accelerators was invented approximately 20 year ago by C. Benvenuti at CERN. This technology have already demonstrated its benefits an many machines: ESRF, Elettra, Diamond, Soleil, LHC, MAX-IV, etc. The NEG coatings are very effective vacuum solution, the UHV/XHV conditions could be reached in fully coated vacuum chamber of particle...
The CiS Forschungsinstitut fuer Mikrosensorik is engaged in developments of radiation detector technologies on several different fields. Current projects are dealing with large area thinned sensors, active edge sensors, 3D sensors, sensor-chip packaging technologies and defect engineering.
For large area sensors, the need for smaller thicknesses can be approached by etching cavities to the...
The vacuum chamber surface characteristics such as the photon and secondary electron yields (PEY and SEY) are critical for formation of an electron cloud, this is a serious problem that effects proton and positron accelerators. A few years ago it was discovered by us that Laser Ablation surface engineering (LASE) could provide surfaces with SEY<1. These LASE surfaces are the baseline design...
Likewise LHC, FCC tunnel should be carefully supervised to ensure safety of personnel. Nevertheless, in case of an accident, in order to increase success of the mission and reduce risks for rescue team, it will be crucial for firefighters to collect as much information as possible about the location of victims inside tunnel before entering the unsafe zone. Due to the large size of FCC, rapid...
The vacuum chamber of the FCC-hh will have to cope with unprecedented levels of synchrotron radiation power, dealing simultaneously with tighter impedance and magnet aperture requirements. Given that the high radiation power and photon flux will release larger amounts of gas into the system, new solutions for designing the beam-screen geometry and estimating the effective pumping speed and...
High field accelerators magnets will require coil grading, and thus low resistance joints (splices), in order to increase the magnetic field and decrease magnet cost. These joints must have low resistance (<1 nΩ) and reasonably good mechanical strength. Three techniques have been initially considered by the Applied Superconductivity group of the Swiss Plasma Center for the preparation of...
We analysed anomalous top FCNC couplings via the production of single top quark in association with a photon at 100 TeV centre of mass energy. In our analysis, we consider the invariant mass distributions of reconstructing top quark mass; one lepton and missing energy transfer reconstructing W, and one b-tagged jet for lvb𝛾 final state, and one b-tagged jet and two other jets reconstructing W...
In this study we consider the results of development and production low temperature superconductors on base of Nb3Sn by the “internal tin” method with critical current density more than 2450 A/mm2. The obtained superconductors of 1.0 to 0.7 mm in diameter of different layouts have been subjected to reaction by various regimes for the formation of the superconducting compound, and then their...
"In the collisions of proposed future circular colliders, like FCCee and CEPC, the beamstrahlung...
An innovative high-field superconducting dipole magnet of Canted-Cosine-Theta (CCT) type has been proposed for Future Circular Collider (FCC) design. The unique mechanical structure intercepts the accumulated forces lowering the stress on the windings. Nevertheless, the former itself also becomes a barrier for heat to quickly propagate in case of a quench. To succeed in the CCT-type magnet...
Developing a surface with low Secondary Electron Yield (SEY) is one of the principal methods of mitigating the beam-induced electron multipacting and electron cloud in high-energy charged particle accelerators. Since the wall material, surface chemistry, topography and electron energy are the parameters that influence the SEY, common mitigation mechanisms are based on engineering the above...
The baseline design of the FCC-hh beam screen is based on an octagonal shaped stainless-steel tube coated in its interior with copper. The surface impedance of the beam screen has a strong impact on the beam stability. In the foreseen operating temperature range from 40 K to 60 K the intended coating might not guarantee an impedance sufficiently low for a stable beam. This motivates the...
"Right-handed or, equivalently, sterile neutrinos are among the most attractive extensions of the SM to generate the light neutrino masses observed in neutrino oscillation experiments.
When the right-handed neutrinos are subject to a ""lepton number""-like symmetry they can have masses around the electroweak scale and potentially large Yukawa couplings, which makes them testable at the...
After the discovery of Higgs boson in LHC of CERN, Chinese scientists immediately proposed a plan to build next generation colliders -- CEPC&SPPC. SPPC (Super Proton Proton Collider) is the second phase of this project to explore new physics beyond the standard model. The key design goal for SPPC is to reach 75 TeV in center of mass energy with a circumference of 100 km. As an important part...
In the Highest Energy Proton Circular Collider ever designed, FCC-hh, a large production of Synchrotron Radiation (SR) is expected. This SR causes heat load on the accelerator walls, photon stimulated desorption, production of secondary electrons, beam instability, etc. Thus, it is very important to have an experimental characterization of optical properties of technical surfaces, in...
One of the many important parameters to be studied and fixed in the design of the FCC-hh is the operational temperature (T) at which the foreseen beam screen should operate. Such choice will necessarily be a compromise between the desire to reduce cooling costs (keeping it at as close as possible to room T) and to have a minimal wall resistivity (keeping it at as low as possible Ts). The...
Nb3Sn wire is the proposed type II superconductor to be used as the superconducting dipole magnet in Future Circular Collider (FCC) for its superior superconducting properties at high magnetic field (16T). Heat treatment and phase formation of Nb3Sn internal tin superconductors are quite complicated due to the need to convert low melting temperature tin-rich phases to high temperature...
The μ-RWELL has been conceived as a compact, simple and robust Micro-Pattern Gaseous Detector for large area HEP applications in a harsh environment. The detector amplification stage is realized with a polyimide foil micro-patterned with a blind-hole matrix embedded through a thin DLC resistive layer in the readout PCB. The introduction of this layer, mitigating the transition from streamer to...
The latest expected sensitivities for the search of flavor changing neutral current processes in top events at the FCC-ee collider run at 365 GeV will be presented in this poster.
Due to its advantages such as evenly distributed pumping speed, low thermal outgassing and low photon and electron stimulated desorption yields, the non-evaporable getter (NEG) coating has been used in particle accelerators for years. Even though quaternary Ti-Zr-Hf-V coating deposited from an allow wire has been found to have the lowest desorption yields, highest sticking probability and...
A bulk superconducting magnetic shield can create the sharp transition between the high-field and no-field zones of septum magnets. This technique promises to reach significantly higher fields than what is possible with current technology, without compromising compactness. The experimental results with three different shield materials will be presented and compared. Simulation results...
We present the status of the Canted-Cosine-Theta (CCT) design of an FCC-hh / HE-LHC dipole, its magnetic and mechanical properties, as well as its protectability. We will develop on the strengths and challenges of this design and lay out the R&D plan at Paul Scherrer Institute to address the challenges, together with first practical results.
This presentation will review the projected accelerator performance and the physics opportunities for a heavy-ion programme at FCC-hh [1]. In addition, the status of the FCC-hh detector design studies will be discussed.
Operating FCC-hh with heavy-ion beams would provide Pb-Pb and p-Pb collisions at center of mass energy of 39 and 63 TeV per NN pair, respectively. Current estimates indicate...
One of the aspects studied during the design of the 16 T Nb3Sn dipole magnets was their safety during quenches occurring in magnet operation and testing. To ensure that the foreseen quench protection technologies can limit the magnet temperatures and voltages to safe values, several criteria related to quench protection were included in the magnet design. As the magnet designs matured,...
The 100 km FCC-ee e+/e- circular collider requires luminosities in the order of 10^35 cm^-2 s^-1 and very low emittances of 1nm for eps_x and 2pm for eps_y. In order to reach these requirements, extreme focusing of the beam is needed in the interaction regions, leading to a vertical beta function of 2mm at the IP. These challenges make the FCC-ee design particularly susceptible to...
FCC-ee will be a precision measurement tool for Z, W, H and t physics with expected luminosities of 2.07 × 10^36 cm−2 s−1 at the Z-pole and 1.3 × 10^34 cm−2 s−1 at the tt ̄ threshold. In order to achieve the foreseen luminosities, a vertical β* of 1 mm to 2 mm is mandatory. Dynamic aperture and frequency maps for the 97.75 km machine are studied. Furthermore, effects of machine misalignments...
Within the FCC project, the EuroCirCol Work Package 5 is dedicated to the design of 16 T Nb3Sn superconducting dipole magnets. Three main aspects are considered during the design phase, i.e. the optimization of the electromagnetic performance of the dipole magnets, their mechanical structure and quench protection design. Various numerical models have been built for their analysis, employing...
Logistics is of great importance for the construction, assembly and operation of the FCC. During the planning, construction and assembly of LHC, logistics already proved to be one of ten key factors. For the planning of FCC several logistics aspects were analysed or discussed:
1. Supply strategies for FCC cryo-units;
2. Locations for the storage, assembly and testing facilities;
3. Transport...
The wide range of beam energies of the FCC-ee accelerator presents unique challenges to the interaction region. An update of this design will be discussed with emphasis on the basic choices and its mechanical constraints. A first 3d mechanical design of the IR will be presented addressing some open questions.
Beam-gas induced background has been studied for the MDI region of the FCC-ee at all the operating running energies. Beam loss maps with characterization of the lost particles and full analysis is perfomed with MDISim. Vacuum requirement in the upstream region before the IR and the IR itself is presented. The loss particles can eventually be tracked in the geant4 detector model and luminosity...
A 100 TeV hadron collider in a 100 km long tunnel is selected as the baseline of the overall infrastructure for the present FCC study. The cooling requirements for FCC-hh cryogenic system are challenging with a very large refrigeration capacity (100 kW equivalent at 4.5 K) up to 3 to 4 times larger than the present state-of-the-art and a non-conventional thermal load distribution with very...
US Magnet Development Program (MDP) is developing a 15 T Nb3Sn dipole demonstrator for a post-LHC pp Collider. The magnet design is based on 60-mm aperture 4-layer shell-type coils, graded between the inner and outer layers to maximize the magnet performance. An innovative mechanical structure based on aluminum IC-clamps and a thick stainless steel skin was developed to preload brittle Nb3Sn...
The mixed refrigerant turbo Brayton cycle with neon and helium was initially designed to cool the beam screens of the FCC in a temperature range from 40 K to 60 K. The current cryogenic design of this cycle for the FCC-hh can use refrigeration above 25 K for other purposes as well, e.g. for the cool-down of the magnets, thus saving large amounts of LN2 required otherwise, or transient...
FCC-ee is a high luminosity lepton collider designed to cover the beam energy range from the Z pole (45.6 GeV) to the top pair threshold (175 GeV). One of the major issues for this machine is represented by collective effects due to electromagnetic fields generated by the interaction of the beam with the vacuum chamber, which could produce instabilities and limit the machine performance. This...
The future circular hadron-hadron collider FCC-hh is expected to produce collisions at the unrivaled center of mass energy of sqrt(s) = 100 TeV and to deliver an integrated luminosity of few tens of ab-1. As a result, billions of Higgs bosons will be produced. Having at disposal such humongous samples opens a wide range of possibilities in the realm of precision Higgs measurements. The Top...
We analyze effects of the Higher Order Modes (HOM) heating in the FCC ee Interaction Region (IR). Interacting beams excite electromagnetic waves in the complicated geometry of the beam chamber. We discuss a possibility to design a chamber with a minimum RF impedance and suggest using HOM absorbers in the IR to capture the main part of the excited electromagnetic waves.
For space and cost reasons, the Nb3Sn accelerator magnets for FCC should be graded. The joint between the two conductor grades should be conveniently done before the heat treatment (wind-and-react joints) for a compact design, without fragile protrusions from the winding packs. In collaboration between CERN and the Swiss Plasma Center (SPC) an R&D program is carried out to develop reliable,...
Power quality is today a primary concern for the operation of CERN’s particle accelerators, and its importance will even increase for the FCC. Nowadays, transient voltage dips, generally coming from the 400 kV network, frequently cause undesired stops of the accelerators and, consequently, are a major contributor for accelerator downtime. Due to its much larger extent, the FCC will be exposed...
An important test of the Standard Model (SM) electroweak symmetry breaking sector is the measurement of the Higgs self-interactions. Sensitivity to the Higgs self-coupling for mH = 125 GeV is evaluated through the measurement of the non-resonant di-Higgs production final states. The considered decay channels are HH→ bb\gamma\gamma, 4b+jet, bb\tau\tau, and bbVV, where V=W and Z. For the...
The bunch by bunch feedback systems for FCC-ee shall be designed on the basis of the experience developed working on the lepton circular colliders in the last two decades. Along the past years a common way to approach these systems has been carried on for PEP-II, KEKB, DAFNE, and, later, for SuperB and SuperKEKB. Nevertheless the advance of the technology as well as the very high performance...
FCC-ee collider rings necessitate top-up injection due to the short luminosity lifetime. Previous studies revealed that the conventional and multipole-kicker injection schemes are applicable. The designs of the injection straight section based on these schemes have been elaborated and will be presented. Further investigations, including feasibility of injection devices, filling scheme, failure...
Investigating the physics of the top quark at the Future Circular hadron-hadron Collider (FCC-hh) is a very exciting prospect. Considering that at the FCC-hh the QCD top-quark production cross section will be 40 times larger than in the LHC, there is a lot of potential for unveiling possible connections with Beyond-the-Standard Model phenomena. In this talk we will discuss the sensitivity of...
In this talk CEPC CDR design status with timeline will be presented which includes parameters, beam-beam simulation, collidering ring lattice design, dynamic apertures, booster design, SCRF system design for both collider ring and booster, linac injector design, MDI design, power consumption, site selections, etc. As for CEPC R&D status and plan for TDR will be presented also. Other issues...
"The feasibility of a future proton-proton collider (FCC-hh), with center of mass energies up to 100 TeV and unprecedented luminosity is currently being studied.
By delivering an integrated luminosity of few tens of ab-1, such a machine will provide an outstanding discovery potential for new physics, far beyond the reach of high luminosity or high energy LHC. In this talk we will discuss...
CEPC is the future Circular Electron and Positron Collider proposed by China to mainly study the Higgs boson. This paper will present the bean optics design of the collider ring for the concept design report. The compatible beam optics for W and Z mode will be presented as well.
The Future Circular Collider (FCC) will require 696 double aperture lattice sextupoles, 9336 single aperture sextupole corrector magnets and 480 double aperture octupoles. The tunnel length and the overall integrated field of the main dipoles have to be kept constant so that the FCC can both reach the specified centre of mass collision energy and fit into the Geneva basin. Considering these...
A proton-proton collider at 100 TeV center-of-mass energy opens up new territory at the energy frontier. Measurements in this energy regime would allow us to test the structure of the Standard Model (SM) with unprecedented precision, as well as enable searches for physics beyond the SM (BSM) involving very massive particles. One of the most appealing BSM theories is supersymmetry (SUSY). The...
Circular Electron-Positron Collider (CEPC) is a 100 km ring e+ e- collider for a Higgs factory. The injector of CEPC is composed of linac and booster. The linac is a normal conducting S-band linac with frequency in 2856.75 MHz and provide electron and positron beam at an energy up to 10 GeV with bunch charge larger than 1.5 nC and repetition frequency in 100 Hz. The linac design will be...
In the past years, a considerable amount of work has been performed in Radiation-to-Electronics (R2E) field for LHC. The CERN’s R2E-project is currently involved in the study of the critical areas for electronics for FCC. Indeed, FCC will require a significant amount of electronic components in the accelerator tunnel and in the side galleries to control and monitor different systems, e.g....
The requirements for the Final Focus Quadrupoles of FCC-ee are very stringent in terms of field quality and compactness of the design. We are happy to report that we have a design based on the Canted Cosine Theta concept that fullfills all requirements: Very compact design (distance of magnetic centres of the two quadrupoles at the tip 66mm), excellent field quality (less than 0.1units in all...
Possible extensions of the Higgs sector can be searched for a wide range of parameter space in the high energy proton-proton collisions. We have studied the charged Higgs boson single production within the framework of two Higgs doublet model in the proton-proton collisions at the FCC-hh collider. The production of charged Higgs boson through pp->H±X process is explored in the mass range 0.5...
To safely and reliably extract the high energy FCC-hh beam is a challenge for the extraction and dilution kicker system and has a major impact on the design. A high segmentation is proposed for both the extraction and the dilution kicker magnets to reduce the impact of one erratic module and to enable operation with less than nominal kick strength. The main challenge for the extraction kicker...
Coherent Synchrotron Radiation (CSR) encountered in the FCC-ee injector bunch compressor can lead to transverse emittance dilution, undoing some of emittance reduction from the damping ring. The bunch compressor is required to reduce the RMS bunch length from 5 mm to 0.5 mm, prior to injection into the linac. This is achieved through a dogleg comprised of two triple-bend achromats (TBA)...
Evacuation is one of the biggest challenges for the fire safety design for the Future Circular Collider (FCC). The configuration of the accelerator, where the distance to the nearest exit to the surface might be up to several kilometers, requires an evacuation design that ensures the occupants move away from the location of the fire, even if they do not know where it is located. An evacuation...
"Calorimetry with liquid argon as the active medium has been chosen as the baseline technology for large parts of the FCC-hh calorimeters. This includes the barrel electromagnetic (EM) calorimeter, the endcap EM and hadronic calorimeter and the forward calorimeter. These calorimeters have to meet the requirements of high radiation hardness and must be able to deal with a very high number of...
The FCC-ee booster synchrotron is a 97.75 km long full energy injector performing continuous top-up injection, since the beam lifetime of the collider is very short because of beamstrahlung and radiative Bhabha scattering.
This talk presents the two optics foreseen to obtain similar emittances as in the collider at different operation modes. Particular emphasis is put on the investigation of...
FCC will require a significant amount of electronic components in the accelerator tunnel and in the side galleries to control and monitor different systems, e.g. power converters, QPS, interlocks, etc. An “a priori” evaluation of the radiation environment, the technology that would be required, the failure rate and the possible mitigation actions become strategic for the design, the future...
For precise beam energy measurements at 45 and 80 GeV
the use of resonant depolarization
has been suggested for FCC e+e-.
The principle behind resonant depolarization is that a
vertically polarized beam excited through an oscillating horizontal magnetic field
gets depolarized when the excitation frequency is in a given relationship with the beam
energy.
The studies of the possibility of...
The goal of beam energy calibration is to define central mass energy at the interaction point (IP). The most accurate method is resonant depolarization technique with relative error of 1 ppm in single beam energy calibration. The whole procedure consists of measurement of spin precession frequency, and calculations of beam energy averaged over circumference, beam energy at IP and central mass...
Particle detectors for high-energy physics applications can contain billions of MOS transistors, each of them prone to possible radiation-induced failures. The Future Circular Collider represents an unprecedented challenge to the radiation hardness of CMOS technology, with an estimated total ionizing dose (TID) from 10 to 500 times higher than the already very high TID expected to be reached...
The design of a muon detector and first-level muon trigger system for the FCC-hh baseline experiment is presented. Drift-tube chambers operated with Ar:CO2 (93:7) gas mixture at 3 bar provide a robust and cost effective solution for precise track point and angle measurement over large areas (about 1200 square meters) with the required resolution of better than 50 µm and 70 µrad, respectively....
The top quark flavor changing neutral current (FCNC) processes are extremely suppressed within the standard model (SM), however they could be enhanced in a new physics model beyond the SM. The top quark FCNC interactions would be a good test of new physics at present and future colliders. For a wide framework of these models, these interactions can be described by the effective Lagrangian. In...
Current solid-state devices for radiation measurement are not capable of integrating the radiation levels expected in certain sectors of the FCC tunnel (tens of KGy with >1015 particles/cm2) and even more in the experiments of the FCC (tens of MGy, with >1017 particles/cm2). In order to overcome these measurement limitations, we have focused our research on metal nanolayers, as a solution for...
Both future 100 km in circumference electron-positron colliders CEPC and FCC-ee want know beams energies with the extreme precision of 1-2 ppm. This can be done only with the help of the well-known resonant depolarization technique. Still, some beam parameters of these machines, like energy spread and radiative damping decrements, becomes so high near or above 80 GeV per beam, that it is...
Data acquisition has always been a significant challenge at a hadron collider. The combination of high luminosity and finely segmented detectors yields data rates that far exceed what can be stored permanently. The problem has traditionally been solved using a trigger system, that performs event selection online. In many cases, the trigger system has relied on dedicated detectors, or detectors...
Doubling the energy reach of the LHC by upgrading magnets with niobium-tin technology challenges optics design in several aspects. The machine layout and transverse dimensions have to fit in the existing tunnel. The larger energy swing together with features from the new niobium-tin technology deteriorate magnetic field quality, affecting both the linear and non-linear beam dynamics. A large...
Additive manufacturing technology and its applications steadily grew from the niche product to the multipurpose manufacturing solution, which today is being applied in many fields of mechanical engineering and machine building technologies. In particular laser cladding proved its high efficiency, precision and economic benefits in repair sectors of aerospace, automotive and ship repair...
The impedance model together with the status of electron cloud simulations for FCC-hh will be presented. Thresholds for transverse coupled bunch instabilities, for mode coupling instabilities and the requirements for Landau damping in FCC-hh will be discussed and compared to LHC.
The High Energy LHC (HE-LHC) is one option for a next generation hadron collider explored in the FCC-hh programme. The core concept of the HE-LHC is to install FCC-hh technology magnets in the LHC tunnel. The higher beam rigidity and the increased radiation debris, however, impose severe challenges on the design of the triplet for the low beta insertions. In order to achieve 25 cm beta*...
In comparison to the LHC beamscreen, the FCC beamscreen is more compact, has much larger pumping holes for achieving high vacuum, and incorporates a surface treatment for electron cloud mitigation. All of these factors can dramatically increase coupling impedance of the beamscreen. The impact on the coupled bunch and the single bunch instabilities is analysed. The necessary pumping hole...
Transverse feedback systems are used for injection oscillation damping and transverse coupled bunch instability mitigation. The FCC-hh sets new challenges in comparison to the LHC due to the more rigid beam during the injection and the faster coupled bunch instability growth rate, which mitigation relies increasingly on the transverse feedback system. In this presentation, the performances of...
Particle flow combines the information from all subdetectors for an optimal reconstruction of all particles in the final state of the collision: charged hadrons, photons, neutral hadrons, electrons, and muons. This technique demonstrated superior performance in past and present experiments, both in ee and pp collisions (ALEPH, CMS), and is now envisioned for future collider experiments. The...
Design of the HE-LHC, which will reach approximately twice the centre of mass energy of the LHC, in an already existing tunnel is challenging for optics design.
To efficiently generate lattices with different parameters, strong effort has been put in developing an automatic lattice generation application. By focusing on two different arc options, namely 18 or 23 cells per arc, merits are...
Electron clouds can cause several unwanted effects, in particular beam instabilities, emittance growth and tune shifts, as well as additional heat load on the cryogenic system and vacuum degradation. These effects can most efficiently be mitigated by suppressing the formation of electron clouds. In this contribution we present the required conditions for sufficient electron cloud suppression...
This talk summarizes the results and activities of the RD50 collaboration in the development of silicon detectors for hadron colliders. The focus of the collaboration is the improvement of the detectors' radiation hardness, with an emphasis on high-luminosity LHC applications. The radiation damage mechanisms of silicon detectors are introduced, together with the activities to develop models...
Electron clouds pose an intensity and luminosity limitation for proton beams in LHC and its upgrades.
The limitations are due to electron cloud induced heat loads, instabilities and also incoherent beam intensity effects. At present, electron cloud induced effects are well controlled in LHC using different counter-measures, like for example coatings and bunch filling pattern, together with...
An alternative energy extraction system of the FCC superconducting circuits capable of energy recuperation is proposed. This system is suggested to comprise a converter module, which by controlling the extraction voltage across the magnet chain will determine the energy extracted and transferred to a temporary storage unit, before being re-used e.g. for the following energy ramp. The...
As part of the Future Circular Collider (FCC) study, a high energy upgrade of the LHC (HE-LHC) is studied. Putting this accelerator with twice the center of mass energy in the existing LHC-tunnel relies on the 16 T dipoles developed for the FCC-hh. Using recent field quality tables of these niobium-tin magnets, the dynamic aperture for different injection energies and two lattices is...
In proton colliders, Landau octupoles are used to provide the necessary Landau damping of transverse coherent beam instabilities driven by the impedance. During the operational cycle the tune spread provided by the Landau octupoles may be modified when in presence of beam-beam interactions. Transverse beam stability studies for the FCC-hh operational cycle will be explored using Landau...
A first version of the HE-LHC impedance was derived from the LHC and HL-LHC impedance models. In these models, two main sources of impedance are considered: the beam screen and the collimation system. The proposed injection energies were evaluated with respect to impedance and transverse beam stability. Because of the tighter physical gaps in the collimators at top energy (13.5 TeV), the...
The Muon system of a FCC detector, both for the leptonic as well as for the hadronic collider, will have to cover an area of several thousands of square meters and possess accurate time and coordinate resolutions in order to provide a precise momentum resolution. The muon detector will also need to provide a standalone muon trigger, bunch crossing identification and be able to match muons...
For the success of the FCC, one of the key aspects is the energy efficiency. In particular, the magnet powering could represent an enormous power consumption from the AC network, therefore achieving an optimised and efficient design for all power converters is a primary concern.
In this presentation, the main concepts and requirements for the power converters for the dipole magnets of the FCC...
The design of the FCC-hh extraction systems is driven by the challenge to safely extract the 50 TeV proton beam. The new baseline for the beam dump system design foresees a fast single plane extraction realized by a highly segmented kicker system and a combination of SuShi (Superconducting Shield) and superconducting Cosine-Theta septa. In the dumpline a focusing structure is included to...
Due to the high energy of the injected FCC-hh proton beam (1.3 or 3.3 TeV) a detailed evaluation of the injection design regarding potential failure cases is of major importance. Further attention has to be given to the fact that the injection is – as in LHC - located upstream of the side experiments.
Resulting design and hardware specifications for the extraction from the High Energy...
