Susana Izquierdo Bermudez

Impedance measurements have long been used to study superconducting magnets in their non-energized state, providing valuable insights into their electromagnetic behaviour. However, studies involving powering have primarily been conducted at low currents, due to the impact of the power converter impedance on the measurement. This paper presents a comprehensive set of impedance measurements on the powered MQXFS7 superconducting magnet, marking the first time such measurements have been performed up to its nominal operating current of I=16.23kA. The magnet's impedance was characterized using two distinct measurement configurations: low-frequency (f=10Hz-1KHz) and high-frequency (f=1kHz-45KHz). Measurements were conducted across all powering phases (ramp-up, steady state, and ramp-down) at two cryogenic temperatures T=1.9K and 4.5K. Impedance variations as a function of current were observed at T=1.9K, with the most notable result being an impedance shift towards the impedance measured at T=4.5K as the nominal operating current was approached. We hypothesize that this may be due to the presence of superconducting (Ti–6Al–4V) magnet poles. Being able to measure the impedance of superconducting magnets in a powered state represent a significant improvement in the understanding of impedance-based diagnostics for superconducting magnets, demonstrating their potential for characterizing magnet behaviour under operating conditions.

During the Long Shutdown 3 of the LHC, scheduled to start in 2026, the interaction regions will be upgraded to increase the integrated luminosity by about one order of magnitude. Among the components to be replaced are the MBRD (Main Bending Recombination Dipole, also known as D2), which are double-aperture magnets providing aligned magnetic fields to steer the two beams into the ATLAS and CMS experiments and subsequently recombine them onto their nominal trajectories. To meet the demanding requirements of the High-Luminosity LHC, a new magnet design was developed by INFN-Genova, featuring a larger aperture, a higher operating field, and innovative solutions to mitigate the strong electromagnetic cross-talk between the apertures while ensuring mechanical integrity against the large repulsive Lorentz forces. The development program included the construction of a 1.6-m model, a full-length prototype, and six series magnets, of which four will be installed in the LHC and two kept as spares. Series production is ongoing at ASG Superconductors, and the first magnet has been successfully cold-tested at CERN. This contribution reports on the main challenges faced during series production and discusses the first test results.

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.

The High-Luminosity LHC (HL-LHC) project aims to upgrade the existing LHC machine to increase its integrated luminosity by a factor of ten. A key aspect of this upgrade is the inner triplet (or low-$\beta$) quadrupole magnets, the MQXF, which utilise Nb$_{3}$Sn superconducting magnet technology and reach a conductor peak field of 11.3 T. The MQXFB version, manufactured at CERN, has a magnetic length of 7.2 m, making it the longest Nb$_{3}$ Sn accelerator magnet ever realised. A total of ten MQXFB series magnets are needed for HL-LHC (eight to be installed, and two spares). The mechanical structure is based on an aluminium shell, pre-tensioned at room temperature with a system of water-pressurised bladders and interference keys, which ensure the pre-stress of the coil-pack. The coil pre-load increases after cool-down to 1.9 K thanks to the larger thermal contraction of the aluminium shrinking cylinder compared to the rest of the magnet components. Since this structural design is used for the first time in an accelerator magnet, the accumulated experience of assembling 80% of the magnets provides valuable insights for the potential application of Nb$_{3}$ Sn technology in future colliders. This paper analyses the main measurements for the mechanical assembly of the MQXFB series magnets and assesses the reproducibility of the production.

The SHiP experiment, to be located at CERN in the ECN3 North Area cavern, aims at detecting feebly interacting particles, potentially shedding light on neutrino mass and dark matter. A key component of the detector is the Hidden Sector Spectrometer, potentially the first large-scale, energy-efficient experimental magnet relying on superconducting MgB$_{2}$ cables. This technology, initially developed for the High Luminosity upgrade of the Large Hadron Collider (HL-LHC) at CERN, has been adapted for electromagnets, cooled by gaseous helium (GHe) at about 20 K. We present the current status of the proof-of-principle demonstrator, which features a coil from MgB$_{2}$ cable wound onto an aluminum former and mounted inside a low-carbon steel yoke. The demonstrator has been successfully tested in GHe at 20 K. In the next development, the demonstrator will be upgraded to test indirect cooling of the MgB$_{2}$ cables, while the yoke will remain at ambient temperature. This work represents a validation step toward the design of the spectrometer magnet for SHiP, with a focus on achieving good homogeneity at a magnetic integrated field of 0.65 T.m over a large aperture of 4 m × 6 m. The conceptual design of the magnet is outlined, along with the production challenges.

MCBXF magnets are orbit correctors for the High-Luminosity (HL) Large Hadron Collider (LHC) upgrade. The magnet design consists of two nested dipoles, with an aperture of 150 mm, which is described elsewhere. The magnets have been designed in two physical lengths, namely of 2.5 m (MCBXFA) and 1.5 m (MCBXFB), with the same cross section. The series production of the magnets consists of 5 long and 10 short magnets. The component production is being carried out at CIEMAT and magnet assembly is made at CERN. This paper summarizes the results of the magnetic measurements of the short magnets produced so far, including warm magnetic measurements. The first magnets featured repetitive results regarding field quality. Afterwards, some of the magnets showed a shift of the main harmonics. After careful analysis of the fabrication steps, it was found out that the impregnation mold assembly strategy impacted on the coil dimensions. The shimming plan was tuned to deal with this feature, and the field quality was enhanced accordingly.

A series production of beam separation dipole, MBXF, is underway toward the High-Luminosity Large Hadron Collider upgrade (HL-LHC). So far, High Energy Accelerator Research Organization (KEK) have tested 4 series magnets in our own vertical cryostat, and their quench training performances have been successfully evaluated. The results show different training behaviors, and particularly MBXF3 has a slower training rate even after the thermal cycle (TC). Quench-antenna (QA) signals for such the magnet shows a prominent oscillatory pattern due to mechanical disturbance. In order to understand origin of the different training behaviors, a new data-acquisition system has been introduced to detect QA activities during powering the magnet. The system was first demonstrated in the second cooldown (CD) of MBXF5 (Apr. - May ’25), and the training evolution became clearly visible: Mechanical activities cease with each training cycle while appearance of the activities was confirmed after TC indicating loss of the training memory. We expect that this new detection tool can help to understand the reason of the different training rate, and thus it will be used for rest of the MBXF tests.