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All sourcesNASA NTRSDOE OSTI
DOE OSTI2025

Test Results of the LQXFA/B02 and LQXFA/B03 Cryo-Assemblies for the High Luminosity LHC Upgrade

Here, the US High-Luminosity LHC Accelerator Upgrade Project (AUP) is responsible for delivering cryo-assemblies for the Q1/Q3 quadrupole optical components of the High Luminosity LHC upgrade at CERN. Total of 10 cryo-assemblies containing two Nb3Sn quadrupole magnets per cold mass will be delivered within this program. After the successful test of the first pre-series cryo-assembly in 2023, two more cryo-assemblies were tested at Fermilab's horizontal test facility. Production overview and the test results of the LQXFA/B02 and LQXFA/B03 cryo-assemblies are summarized in this paper. After the first test, to increase the capability of the horizontal test facility, various improvements have been made. These improvements are also described in this paper.

Chlachidze, Guram [Fermi National Accelerator Labo↗
DOE OSTI2016

Quench protection study of the updated MQXF for the LHC luminosity upgrade (HiLumi LHC)

In 2023, the LHC luminosity will be increased, aiming at reaching 3000 fb-1 integrated over ten years. To obtain this target, new Nb 3 Sn low-β quadrupoles (MQXF) have been designed for the interaction regions. These magnets present a very large aperture (150 mm, to be compared with the 70 mm of the present NbTi quadrupoles) and a very large stored energy density (120 MJ/m 3 ). For these reasons, quench protection is one of the most challenging aspects of the design of these magnets. In fact, protection studies of a previous design showed that the simulated hot spot temperature was very close to the maximum allowed limit of 350 K; this challenge motivated improvements in the current discharge modeling, taking into account the so-called dynamic effects on the apparent magnet inductance. Moreover, quench heaters design has been studied to be going into more details. In this study, a protection study of the updated MQXF is presented, benefiting from the experience gained by studying the previous design. As a result, a study of the voltages between turns in the magnet is also presented during both normal operation and most important failure scenarios.

43 PARTICLE ACCELERATORS↗
DOE OSTI2016

Performance of the First Short Model 150-mm-Aperture Nb3Sn Quadrupole MQXFS for the High-Luminosity LHC Upgrade

LHC Accelerator Research Program (LARP) and CERN combined their efforts in developing Nb3Sn magnets for the high-luminosity LHC upgrade. The ultimate goal of this collaboration is to fabricate large aperture Nb 3Sn quadrupoles for the LHC interaction regions. These magnets will replace the present 70-mm-Aperture NbTi quadrupole triplets for expected increase of the LHC peak luminosity up to 5 × 10 34 cm -2 s -1 or more. Over the past decade, LARP successfully fabricated and tested short and long models of 90 and 120-mm-Aperture Nb3Sn quadrupoles. Recently, the first short model of 150-mm-diameter quadrupole MQXFS was built with coils fabricated both by LARP and CERN. The magnet performance was tested at Fermilab's vertical magnet test facility. Here, this paper reports the test results, including the quench training at 1.9 K, ramp rate and temperature dependence, as well as protection heater studies.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2017

Summary of Test Results of MQXFS1—The First Short Model 150 mm Aperture Nb 3 Sn Quadrupole for the High-Luminosity LHC Upgrade

The development of Nb 3 Sn quadrupole magnets for the High-Luminosity LHC upgrade is a joint venture between the US LHC Accelerator Research Program (LARP)* and CERN with the goal of fabricating large aperture quadrupoles for the LHC interaction regions (IR). The inner triplet (low-β) NbTi quadrupoles in the IR will be replaced by the stronger Nb3Sn magnets boosting the LHC program of having 10-fold increase in integrated luminosity after the foreseen upgrades. Previously, LARP conducted successful tests of short and long models with up to 120 mm aperture. The first short 150 mm aperture quadrupole model MQXFS1 was assembled with coils fabricated by both CERN and LARP. The magnet demonstrated a strong performance at Fermilab's vertical magnet test facility reaching the LHC operating limits. This paper presents the latest results from MQXFS1 tests with changed prestress levels. The overall magnet performance, including quench training and memory, ramp rate, and temperature dependence, is also summarized.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2017

Mechanical Design Analysis of MQXFB, the 7.2-m-Long Low- $\beta$ Quadrupole for the High-Luminosity LHC Upgrade

As part of the High-Luminosity Large Hadron Collider (LHC) Project, a set of Nb 3 Sn quadrupoles are being developed, aiming to enhance the performance of the inner triplets. The new magnets, identified as MQXFA and MQXFB, will share the same cross section with two different lengths, 4.2 and 7.2 m, respectively. During the magnet development, three short models were tested, along with a number of mechanical models, demonstrating the capability of the magnet cross section to achieve the specified performances. The same performances are now required for the full-length magnets. To ensure this, the authors studied the impact of the magnet length on the capability of the structure to provide an adequate support to the coils. Finite element and simplified analytical models were used to evaluate the impact of the magnet length on the stresses in the magnet ends and coil elongation during powering. Lastly, the models were calibrated using the results from the short model tests, and used to provide an indication on the required prestress and its foreseen impact on the magnet performance.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2018

Geometric Field Errors of Short Models for MQXF, the Nb3Sn Low-β Quadrupole for the High Luminosity LHC

© 2002-2011 IEEE. In the framework of the high-luminosity upgrade of the large hadron collider, the U.S. LARP collaboration and CERN are jointly developing a 150-mm aperture Nb3Sn quadrupole for the Large Hadron Collider (LHC) interaction regions. Due to the large beam size and orbit displacement in the final focusing triplet, MQXF has challenging targets for field quality at nominal operation conditions. Three short model magnets have been tested and around 30 coils have been built, allowing a first analysis of the reproducibility of the coil size and turns positioning. The impact of the coil shimming on field quality is evaluated, with special emphasis on the warm magnetic measurements and the correlation to field measurements at cold and nominal field. The variability of the field harmonics along the magnet axis is studied by means of a Monte-Carlo analysis and the effects of the corrective actions implemented to suppress the low-order unallowed multipoles are discussed.

Bermudez, Susana Izquierdo↗
DOE OSTI2011

Test Results of 15 T Nb3Sn Quadrupole Magnet HQ01 with a 120 mm Bore for the LHC Luminosity Upgrade

In support of the luminosity upgrade of the Large Hadron Collider (LHC), the US LHC Accelerator Research Program (LARP) has been developing a 1-meter long, 120 mm bore Nb{sub 3}Sn IR quadrupole magnet (HQ). With a short sample gradient of 219 T/m at 1.9 K and a conductor peak field of 15 T, the magnet will operate under higher forces and stored-energy levels than that of any previous LARP magnet models. In addition, HQ has been designed to incorporate accelerator quality features such as precise coil alignment and adequate cooling. The first 6 coils (out of the 8 fabricated so far) have been assembled and used in two separate tests-HQ01a and HQ01b. This paper presents design parameters, summary of the assemblies, the mechanical behavior as well as the performance of HQ01a and HQ01b.

43 PARTICLE ACCELERATORS↗
DOE OSTI2020

The CMS Outer Tracker for the High Luminosity LHC

The High Luminosity LHC (HL-LHC) is expected to deliver an integrated luminosity of 3000 - 4000 fb -1 in its lifetime with peak instantaneous luminosities reaching about 5 - 7.5×10 34 cm -2 s -1 . During the Long Shutdown 3 period, several components of the CMS detector will undergo major changes, called Phase-2 upgrades, to be able to operate in the challenging environment of the HL-LHC, including the replacement of the entire silicon tracker. The Phase-2 Outer Tracker (OT) will have high radiation tolerance, higher granularity, and the capability to handle higher data rates. Another key feature of the OT will be to provide tracking information to the Level-1 trigger, allowing trigger rates to be kept at a sustainable level without sacrificing physics potential. For this, the OT will be made of modules that have two closely spaced sensors read out by the same electronics, which can correlate hits in the two sensors creating short track segments called ”stubs”. The stubs will be used for tracking at 40 MHz. In this contribution, the design of the CMS Phase-2 OT, the technological choices, and highlights of research and development activities are reported.

Ravera, Fabio↗
DOE OSTI2023

The Challenges and Solutions of Meeting the Assembly Specifications for the 4.5 m Long MQXFA Magnets for the Hi-Luminosity LHC

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.

43 PARTICLE ACCELERATORS↗
DOE OSTI2025

Test results of the LQXFA/B02 and LQXFA/B03 cryo-assemblies for the High Luminosity LHC upgrade

The US High-Luminosity LHC Accelerator Upgrade Project (AUP) is responsible for delivering cryo-assemblies for the Q1/Q3 quadrupole optical components of the High Luminosity LHC upgrade at CERN. Total of 10 cryo-assemblies containing two Nb3Sn quadrupole magnets per cold mass will be delivered within this program. After the successful test of the first pre-series cryo-assembly in 2023, two more cryo-assemblies were tested at Fermilab’s horizontal test facility. Production overview and the test results of the LQXFA/B02 and LQXFA/B03 cryo-assemblies are summarized in this paper. After the first test, to increase the capability of the horizontal test facility, various improvements have been made. These improvements are also described in this paper.

Chlachidze, Guram [Fermilab]↗
DOE OSTI2019

The development programme of cathodes and electron guns for the Hollow Electron Lenses of the High Luminosity LHC project1

The High Luminosity LHC project (HL-LHC) foresees the construction and installation of important new equipment to increase the performance of the LHC machine. The Hollow Electron Lens (HEL) is a promising system to control the beam halo. It improves the beam collimation system of the HL-LHC and mitigates possible equipment damage in case of failure scenarios from halo losses. The halo can store up to 30 MJ energy. The specifications for this new device are quite demanding. The source, an electron gun with an annular shaped cathode, has to deliver a current up to 5 A. This is five times higher than the current in the existing electron lenses in Fermi and Brookhaven national laboratories. This note describes the programme carried out to design and test high-perveance guns equipped with two types of high-performance scandate cathodes. The size of the final gun is now considerably smaller than the one of the first prototype, allowing a reduction of diameter and cost of the superconducting magnet system used to steer the electron beam. The tests carried out at FNAL, BVERI and BJUT demonstrated that the developed cathodes fulfil the specifications and can supply a 5 A fully Space Charge Limited (SCL) current.

43 PARTICLE ACCELERATORS↗
DOE OSTI2024

Transverse emittance growth due to rf noise in crab cavities: Theory, measurements, cure, and high luminosity LHC estimates

The High-Luminosity LHC (HL-LHC) upgrade with planned operation from 2029 onward has a goal of achieving a tenfold increase in the integrated number of recorded collisions thanks to a doubling of the intensity per bunch ( 2.2 × 10 11 protons) and a reduction of β * (the β value in the two high luminosity detectors, namely ATLAS and CMS) to 15 cm. Such an increase in recorded collisions would significantly expedite new discoveries and exploration. Crab cavities are an important component of the HL-LHC upgrade and will contribute strongly to achieving an increase in the number of recorded collisions. However, noise injected through the crab cavity radio frequency (rf) system could cause significant transverse emittance growth and limit luminosity lifetime. We presented a theoretical formalism relating transverse emittance growth to rf noise in an earlier work. In this follow-up paper, we summarize measurements in the super-proton synchrotron (SPS) at CERN that validate the theory, we present estimates of the emittance growth rates using state-of-the-art rf and low-level rf (LLRF) technologies, and we set the rf noise specifications to achieve acceptable performance. A novel dedicated feedback system acting through the crab cavities to mitigate emittance growth will be required. In this work, we develop a theoretical formalism to evaluate the performance of such a feedback system in any collider, identify limiting components, present simulation results to validate these studies, and derive key design parameters for an HL-LHC implementation of such a feedback system. Published by the American Physical Society 2024

43 PARTICLE ACCELERATORS↗
DOE OSTI2014

High-field Magnet Development toward the High Luminosity LHC

The upcoming Luminosity upgrade of the LHC (HL-LHC) will rely on the use of Accelerator Quality Nb3Sn Magnets which have been the focus of an intense R&D effort in the last decade. This contribution will describe the R&D and results of Nb3Sn Accelerator Quality High Field Magnets development efforts, with emphasis on the activities considered for the HL-LHC upgrades.

43 PARTICLE ACCELERATORS↗
DOE OSTI2016

First Test Results of the 150 mm Aperture IR Quadrupole Models for the High Luminosity LHC

The High Luminosity upgrade of the LHC at CERN will use large aperture (150 mm) quadrupole magnets to focus the beams at the interaction points. The high field in the coils requires Nb3Sn superconductor technology, which has been brought to maturity by the LHC Accelerator Re-search Program (LARP) over the last 10 years. The key design targets for the new IR quadrupoles were established in 2012, and fabrication of model magnets started in 2014. This paper discusses the results from the first single short coil test and from the first short quadrupole model test. Remaining challenges and plans to address them are also presented and discussed.

43 PARTICLE ACCELERATORS↗
DOE OSTI2016

Mechanical qualification of the support structure for MQXF, the Nb 3 Sn low-β quadrupole for the high luminosity LHC

Within the scope of the High Luminosity LHC project, the collaboration between CERN and U.S. LARP is developing new low-β quadrupoles using the Nb 3 Sn superconducting technology for the upgrade of the LHC interaction regions. The magnet support structure of the first short model was designed and two units were fabricated and tested at CERN and at LBNL. The structure provides the preload to the collars-coils subassembly by an arrangement of outer aluminum shells pre-tensioned with water-pressurized bladders. For the mechanical qualification of the structure and the assembly procedure, superconducting coils were replaced with solid aluminum “dummy coils”, the structure was preloaded at room temperature, and then cooled-down to 77 K. Mechanical behavior of the magnet structure was monitored with the use of strain gauges installed on the aluminum shells, the dummy coils and the axial preload system. As a result, this paper reports on the outcome of the assembly and the cool-down tests with dummy coils, which were performed at CERN and at LBNL, and presents the strain gauge measurements compared to the 3D finite element model predictions.

43 PARTICLE ACCELERATORS↗
DOE OSTI2019

US Contribution to the High Luminosity LHC Upgrade: Focusing Quadrupoles and Crab Cavities

In the early 2000's, the US High Energy Physics community contributing to the Large Hadron Collider (LHC) launched the LHC Accelerator R&D Program (LARP), a long-vision focused R&D program, intended contribute to a quick LHC commissioning and to bring the Nb3Sn and other technologies to a maturity level that would allow applications in HEP machines [1,2]. Around 2015, the technologies developed by LARP, CERN and other institutions were mature enough to allow the spin-off of a major upgrade project to the LHC complex, the High Luminosity LHC (HL-LHC) [3]. This paper will focus on the US contribution to HL-LHC, namely the large-aperture low-β focusing Nb3Sn quadrupoles and the Radio Frequency Dipole (RFD) Crab Cavities, located in close proximity to the ATLAS and CMS experiments. This contribution, called the HL-LHC Accelerator Upgrade Project (HL-LHC AUP), focuses on production of these quadrupoles and cavities by sharing the work among a consortium of US Laboratories (FNAL, LBNL, BNL and SLAC) and Universities and in close connection with the CERN-led HL-LHC Collaboration. The collaboration achieved commonality of specifications and uniformity of performance. Final development of design, construction and first results from the prototypes are described to indicate the status of these critical components for HL-LHC.

43 PARTICLE ACCELERATORS↗
DOE OSTI2019

Field Quality Measurement of a 4.2-m-Long Prototype Low- $\beta$ Nb $_3$ Sn Quadrupole Magnet During the Assembly Stage for the High-Luminosity LHC Accelerator Upgrade Project

The U.S. High-Luminosity LHC Accelerator Upgrade Project, in collaboration with CERN, is developing Nb 3 Sn quadrupole magnets (MQXFA) to be installed at the interaction region of the LHC. The project will deliver 20 MQXFA magnets in 10 cold masses. These magnets need to meet the stringent requirements on field quality at the nominal operating current. Compared to the mature NbTi accelerator magnet technology, achieving excellent field quality can be challenging for Nb 3 Sn magnets. To help track, understand, and allow effective correction of geometric field errors, field quality measurements at room temperature during the MQXFA assembly stage was planned for the project. The measurements also intend to evaluate the magnetic axis and twist angle along the magnet aperture. We report the first measurement on a prototype MQXFA magnet using a recently developed measurement system. The magnetic axis and twist angle met the acceptance criteria. Further development needs for the room-temperature measurements were discussed. Here, we expect that statistics obtained from such measurements throughout the project will provide insight into future applications of high-performance Nb 3 Sn accelerator magnets.

43 PARTICLE ACCELERATORS↗
DOE OSTI2020

The scale of superpartner masses and electroweakino searches at the high-luminosity LHC

Searches for weakly interacting particles is one of the main goals of the high luminosity LHC run. In this work we study the well motivated cases of electroweakinos with mostly Wino and Bino components. We show the relevance of squark induced t-channel production in defining the production cross section and hence the LHC reach. Moreover, a realistic evaluation of the decay branching ratios show a strong dependence on the sign of μ and, for negative values of μ, on the relative size of the ratio of μ to the gaugino masses compared with tan β. Overall, unless it is kinematically suppressed, or specific conditions are fulfilled, the Higgs decay channel is the most significant one, and the trilepton channel becomes subdominant with respect to final states including bottom quarks. Although the properties are different than in the Higgsino-Bino case, also in this case the discovery reach extends to mass values that are significantly larger than the ones probed at current luminosities, leading to a strong motivation for the search for electroweakinos in the high luminosity LHC run.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗