Laura Garcia Fajardo

The Canted-Cosine-Theta (CCT) magnet is known for generating high-quality multipole fields using a continuous winding scheme on a cylindrical surface. In this work, we extend this concept to a conical surface, demonstrating that the distinctive properties of CCT magnets are preserved. The conical CCT dipole presents advantages in confined spaces or environments where multiple beams interact, such as at the interaction points (IP) of particle accelerators. The deployment of conical CCT magnets has the potential reducing the number of magnets along beam lines while still meeting optical specifications. We introduce a discrete winding scheme of line currents for a dipole on a conical surface and provide the magnetic field generated along its length.

Background: Early detection of brain‐related disorders is key to prevention of Alzheimer’s disease (AD), and research on Hispanic populations is severely lacking. Obstacles to recruitment include the lack of trust in research and researchers and requirements for English proficiency, which excludes many potential Hispanic participants.Methods: Researchers from El Faro Health and Therapeutics in Starr County, Texas and the Framingham Heart Study are teaming up on a digital phenotyping study and incorporating “trust” as a central theme for recruitment/retention of Hispanic participants. Study materials are in both English and Spanish. The smartphone tasks are presented in two formats: “in‐clinic” using an iPad and “remote” utilizing participants’ smartphones. Activities include voice tasks, gait and balance, and game‐like cognitive tasks. Longitudinal data will be collected every three months for one year.Participants: Recruitment is for anyone aged 18+ in Starr County, which is approximately 98% Hispanic. To maximize inclusivity, there are no other inclusion/exclusion criteria. Study procedures are customized to accommodate individuals. Recruitment goal is 500 participants within one year, with planned expansion to 5,000+ over 5 years.Results: Recruitment approach includes several components: (1) El Faro investigators have been providing clinical services to community members for decades, and are respected and trusted members of the community. (2) All participant‐facing study materials are available in both English and Spanish, with most translated into the specific local dialect. (3) Community fliers include text in both English and Spanish. (4) Social media outreach has sparked a great deal of interest for participating in research, and the team attends community events to further spread the word. (5) Multi‐generational families are encouraged given family decision‐making culture; (6) Word‐of‐mouth within the Starr County community is expected to be an important contributor to recruitment.Conclusions: Although data collection will begin in February 2023, already more than 150 participants have expressed interest in being involved. Leveraging resources to enable highly respected and trusted local researchers to conduct the research, and using participant‐centric design approaches will result in greater success in recruitment and retention of this underrepresented population.

Within the U.S. Magnet Development Program, LBNL is planning to fabricate and test hybrid magnets combining Nb ₃ Sn and Bi-2212 canted-cosine theta (CCT) magnets. The first planned hybrid magnet test integrates a 1 m long, 90 mm bore Nb ₃ Sn dipole magnet (CCT5), and a 39 cm long, 30.8 mm bore Bi-2212 dipole magnet (BIN5c), which are already fabricated and were tested individually. The second planned hybrid magnet test integrates a 1.5 m long, 120 mm bore Nb ₃ Sn dipole magnet (CCT6), still under design, and a 1 m long, 40 mm bore Bi-2212 dipole magnet (BiCCT1), which is under fabrication. This work gives an update of the status of the Bi-2212 CCT magnet program, and focuses on the first hybrid magnet (CCT5/BIN5c). The electromagnetic and mechanical analysis of the CCT5/BIN5c hybrid magnet is presented, as well as the proposed mechanical assembly process. The quench protection strategy associated with the hybrid magnet test is also presented.

By the end of October 2022, the US HL-LHC Accelerator Upgrade Project (AUP) had completed fabrication of ten MQXFA magnets and tested eight of them. The MQXFA magnets are the low-beta quadrupole magnets to be used in the Q1 and Q3 Inner Triplet elements of the High Luminosity LHC. This AUP effort is shared by BNL, Fermilab, and LBNL, with strand verification tests at NHMFL. An important step of the AUP QA plan is the testing of MQXFA magnets in a vertical cryostat at BNL. The acceptance criteria that could be tested at BNL were all met by the first four production magnets (MQXFA03-MQXFA06). Subsequently, two magnets (MQXFA07 and MQXFA08) did not meet some of the criteria and were disassembled. Lessons learned during the disassembly of MQXFA07 caused a revision to the assembly specifications that were used for MQXFA10 and subsequent magnets. In this article, we present a summary of: 1) the fabrication and test data for all the MQXFA magnets; 2) the analysis of MQXFA07/A08 test results with characterization of the limiting mechanism; 3) the outcome of the investigation, including the lessons learned during MQXFA07 disassembly; and 4) the finite element analysis correlating observations with test performance.

Under the U.S. High Luminosity LHC Accelerator Upgrade Project (HL-LHC AUP), the 150 mm bore, high-field Nb3Sn low-\b{eta} MQXFA quadrupole magnets are being fabricated, assembled and tested, in the context of the CERN Hi-Luminosity LHC (HL-LHC) upgrade. These magnets have 4.2 m magnetic length and 4.56 m long iron yoke. To date, eight MQXFA magnets have been tested. One of the magnets additionally underwent a successful endurance test with 40 triggered quenches, and two magnets did not perform as expected. This work summarizes for the first time the available strain gauge data from eight identical Nb3Sn MQXFA tested magnets, focusing on the endurance test, and on a possible cause of underperformance of the two magnets that did not pass the vertical test. We applied methods to prevent this from happening in future MQXFA magnets, which shown to be effective for last two tested magnets.

Under the U.S. High Luminosity LHC Accelerator Upgrade Project (HL-LHC AUP), the 150 mm bore, high-field Nb ₃ Sn low-β MQXFA quadrupole magnets are being fabricated, assembled and tested, in the context of the CERN Hi-Luminosity LHC (HL-LHC) upgrade. These magnets have 4.2 m magnetic length and 4.56 m long iron yoke. To date, eight MQXFA magnets have been tested. One of the magnets additionally underwent a successful endurance test with 40 triggered quenches, and two magnets did not perform as expected. This work summarizes for the first time the available strain gauge data from eight identical Nb ₃ Sn MQXFA tested magnets, focusing on the endurance test, and on a possible cause of underperformance of the two magnets that did not pass the vertical test. We applied methods to prevent this from happening in future MQXFA magnets, which shown to be effective for last two tested magnets.

The U.S. High-Luminosity LHC Accelerator Upgrade Project (HL-LHC AUP) has, in the recent years, developed assembly specifications for the 4.5 m long MQXFA magnets, which are 150 mm aperture high-field Nb ₃ Sn low-β quadrupole magnets that are being built for the CERN Hi-Luminosity LHC (HL-LHC) upgrade. While the specifications were based on lessons learned from the LHC Accelerator Research Program (LARP) effort and the MQXFS and MQXFA prototype magnets, the experience gained from having both MQXFA07 and MQXFA08 magnets not meeting performance specifications during cold testing actually catalyzed a better understanding of the impact of the target assembly specifications and a subsequent refinement of the same. This paper summarizes a body of assembly data from the Pre-Series (MQXFA03-MQXFA07) and Series magnets (MQXFA08-MQXFA11) that have been built to date, and discusses the processes employed to successfully face the challenge of ensuring that the assembly specifications are met for the duration of the project.

Hybrid magnets are currently under consideration as an economically viable option towards 20 T dipole magnets for next generation of particle accelerators. In these magnets, High Temperature Superconducting (HTS) materials are used in the high field part of the coil with so-called “insert coils”, and Low Temperature Superconductors (LTS) like Nb ₃ Sn and Nb-Ti superconductors are used in the lower field region with so-called “outsert coils”. The attractiveness of the hybrid option lays on the fact that, on the one hand, the 20 T field level is beyond the Nb ₃ Sn practical limits of 15-16 T for accelerator magnets and can be achieved only via HTS materials; on the other hand, the high cost of HTS superconductors compared to LTS superconductors makes it advantageous exploring a hybrid approach, where the HTS portion of the coil is minimized. We present in this paper an overview of different design options aimed at generating 20 T field in a 50 mm clear aperture. The coil layouts investigated include the Cos-theta design (CT), with its variations to reduce the conductor peak stress, namely the Canted Cos-theta design (CCT) and the Stress Management Cos-theta design (SMCT), and, in addition, the Block-type design (BL) including a form of stress management and the Common-Coil design (CC). Results from a magnetic and mechanical analysis are discussed, with particular focus on the comparison between the different options regarding quantity of superconducting material, field quality, conductor peak stress, and quench protection.

High-temperature superconducting REBa $_{2}$ Cu $_{3}$ O $_{7-x}$ ( rebco ) conductors have the potential to generate a high magnetic field over a broad temperature range. The corresponding accelerator magnet technology, still in its infancy, can be attractive for future energy-frontier particle colliders such as a multi-TeV muon collider. To help develop the technology, we explore the requirements and potential characteristics of a rebco magnet, operating at 4.2 or 20 K, with a dipole field of 8–10 T in a clear aperture of 150 mm. We use the canted $\cos \theta$ magnet configuration to reduce the electromagnetic stresses on the conductors. We present the resulting dipole fields, field gradients for combined-function cases, conductor stresses, magnet dimensions and conductor lengths. We also discuss the conductor performance that is required to achieve the target dipole field at 4.2 and 20 K. The information can provide useful input to the development of rebco magnet and conductor technology for collider-ring magnets in a muon collider.