Since the initial data taking of the CERN LHC, the CMS experiment has undergone substantial upgrades and improvements. This paper discusses the CMS detector as it is configured for the third data-taking period of the CERN LHC, Run 3, which started in 2022. The entire silicon pixel tracking detector was replaced. A new powering system for the superconducting solenoid was installed. The electronics of the hadron calorimeter was upgraded. All the muon electronic systems were upgraded, and new muon detector stations were added, including a gas electron multiplier detector. The precision proton spectrometer was upgraded. The dedicated luminosity detectors and the beam loss monitor were refurbished. Substantial improvements to the trigger, data acquisition, software, and computing systems were also implemented, including a new hybrid CPU/GPU farm for the high-level trigger.

Volume 1 of the FCC Feasibility Report presents an overview of the physics case, experimental programme, and detector concepts for the Future Circular Collider (FCC). This volume outlines how FCC would address some of the most profound open questions in particle physics, from precision studies of the Higgs and EW bosons and of the top quark, to the exploration of physics beyond the Standard Model. The report reviews the experimental opportunities offered by the staged implementation of FCC, beginning with an electron-positron collider (FCC-ee), operating at several centre-of-mass energies, followed by a hadron collider (FCC-hh). Benchmark examples are given of the expected physics performance, in terms of precision and sensitivity to new phenomena, of each collider stage. Detector requirements and conceptual designs for FCC-ee experiments are discussed, as are the specific demands that the physics programme imposes on the accelerator in the domains of the calibration of the collision energy, and the interface region between the accelerator and the detector. The report also highlights advances in detector, software and computing technologies, as well as the theoretical tools/reconstruction techniques that will enable the precision measurements and discovery potential of the FCC experimental programme. The content and structure of this report are guided by the scope and priorities defined in the mandate of the FCC Feasibility Study. It is therefore not intended to serve as an exhaustive review of the full physics potential of FCC. Several topics, already covered in earlier reports such as the FCC CDR, are not reiterated here or are addressed only briefly, in alignment with the study’s focus. This volume reflects the outcome of a global collaborative effort involving hundreds of scientists and institutions, aided by a dedicated community-building coordination, and provides a targeted assessment of the scientific opportunities and experimental foundations of the FCC programme.

We have developed a high-temperature superconducting (HTS) flux pump using high-power metal-oxide-semiconductor field-effect transistors (MOSFETs) for switching. For its primary coil, two commercial transformers are utilized, each consisting of two copper coils wound on a single iron core, which enables changing the load current over primary current ratio (101 or 194) between the primary and secondary coils. Full-wave rectification is achieved with two half-wave secondary circuits, each of them having six HTS one-turn coils to lower the resistance. Each secondary coil is composed out of nickel-reinforced BSCCO tapes, where 12 MOSFETs have been soldered in parallel straight to the tapes and controlled with analog electronics. Secondary coils are clamped to custom-made copper-stabilized HTS current leads. A support structure for keeping the HTS coils in place was 3D-printed using cryogenic-compatible composite material PETG-CF20. Resistances of the two secondary circuits were measured to be 4 μ Ω and 7 μ Ω at 77 K with a total critical current of 980 A. We successfully ramped up a 50 µH Conductor on Round Core solenoid at 77 K using our HTS flux pump with 50 Hz AC voltage source. We achieved a maximal load current of 900 A and exceeded the 715 A critical current of the solenoid. During the thermal runaway of the magnet, the increased load voltage limits the maximum load current supplied by the flux pump.

Particle physics experiments make use of magnetic fields up to $4 \,\mathrm{T}$ to bend electrically charged particles such that their charge and momentum can be determined. The particle energy measurement requires a low amount of material, or material that is highly transparent to particles inside the calorimeter volume. The conflict between the small volume of space reserved for a magnet and having a field of several teslas inside the detector is often resolved by using superconducting magnets. Up to now, large particle physics detector magnets have been constructed with low temperature superconductors, but there are clear benefits from using high temperature superconductors in future particle physics detector designs, such as allowing for an elevated operating temperature and the reduced amount of superconductor needed. In addition to the HTS material itself, additional material is needed to support the Lorentz forces, and to temporarily carry the current in case of a quench since these magnets are always one-of-a-kind and they need to operate reliably and without damage in case of a failure scenario. The stabilizer has to be a low-density material for high particle transparency, such as aluminium. Since the density of the superconductor is a factor of 4 higher than the density of aluminium, a reduction of superconducting material also means an improvement of the particle transparency: the density of a material is directly related to its particle transparency. This paper presents a conceptual design for high temperature superconducting detector magnets and a study of the type of aluminium stabilizer used.

As part of the Future Circular Collider conceptual design study for hadron-hadron physics (FCC-hh), conceptual designs of detector magnets are being developed to facilitate the measurement of particle products resulting from the 100 TeV collisions. This paper discusses the design evolution leading from a 65 GJ Twin Solenoid with forward dipoles design to the present baseline design which features three superconducting solenoids. The central magnet produces 4~T over a free bore of 10 m and a length of 20 m. The forward solenoids provide additional bending power to facilitate tracking of high-pseudo-rapidity particles. The combined stored energy of this system is 13.8 GJ. This design is discussed in terms of powering and quench protection, conductor composition, mechanical properties of the cold masses and vacuum vessels, stray fields, and heat loads. In addition, alternative designs are discussed, including an ultra-thin superconducting solenoid concept with comparatively low stored magnet energy. Like the ATLAS central solenoid, this solenoid provides a magnetic field to the tracker, and particles have to tunnel through the solenoid before reaching the calorimeters. An iron yoke returns the flux, thus providing bending power for muon tagging and giving complete magnetic shielding.

Within the context of EP R&D, CERN is developing a high-temperature superconducting (HTS) conductor for future superconducting detector magnet projects. The conductor features a Rare-Earth Barium Copper Oxide (REBCO) tapes soldered to a copper-coated high-purity aluminium stabilizer. Critical currents of the 200 mm long straight cable samples measured with various numbers of REBCO tapes at 77 K are consistent with empirical scaling formulas for critical current within 10%. A few percent deviations are expected to arise from the critical current variation along the length of the HTS tape. No degradation was observed after multiple soldering and de-soldering cycles at 165 $^\mathrm{o}$ C with Bi–Sn based solder and after thermal cycling between 77 K and room temperature. However, extreme bending (of 100 mm radius) of the already soldered HTS cable leads to failure of the cable. We repeated the critical current measurements with a 650 mm long cable loop sample with 85 mm bending radius, where the HTS tapes were soldered after the aluminium profile was bent. The critical current of the HTS cable loop was 7% lower than the prediction. Based on the first critical current measurements, the HTS cable preparation method presented in this work results in repeatable quality aluminium-stabilized HTS cable.