158 research outputs found
Analysis of the mechanical performance of the 4.2 m long MQXFA magnets for the Hi-Lumi LHC Upgrade
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
Optimizing the use of pressurized bladders for the assembly of HL-LHC MQXFB magnets
The use of pressurized bladders for stress control of superconducting magnets
was firstly proposed at Lawrence Berkeley National Laboratory (LBNL) in the
early 2000s. Since then, the so-called bladders and keys procedure has become
one of the reference techniques for the assembly of high-field accelerator
magnets and demonstrators. Exploiting the advantages of this method is today of
critical importance for Nb3Sn-based accelerator magnets, whose production
requires the preservation of tight stress targets in the superconducting coils
to limit the effects of the strain sensitivity and brittleness of the
conductor. The present manuscript reports on the results of an experimental
campaign focused on the optimization of the bladders and keys assembly process
in the MQXFB quadrupoles. These 7.2 m long magnets shall be among the first
Nb3Sn cryomagnets to be installed in a particle accelerator as a part of the
High Luminosity upgrade of the LHC. One of the main practical implications of
the bladders technique, especially important when applied to long magnets like
MQXFB, is that to insert the loading keys, the opening of a certain clearance
in the support structure is required. The procedure used so far for MQXF
magnets involved an overstress in the coils during bladder inflation. The work
presented here shows that such an overshoot can be eliminated thanks to
additional bladders properly positioned in the structure. This optimized method
was validated in a short model magnet and in a full-length mechanical model,
becoming the new baseline for the series production at CERN. Furthermore, the
results are supported by numerical predictions using Finite Element models
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Second-Generation Coil Design of the Nb3Sn low-β Quadrupole for the High Luminosity LHC
As part of the Large Hadron Collider (LHC) Luminosity upgrade program, the U.S.-LHC Accelerator Research Program collaboration and CERN are working together to design and build a 150-mm aperture Nb3Sn quadrupole for the LHC interaction regions. A first series of 1.5-m-long coils was fabricated and assembled in a first short model. A detailed visual inspection of the coils was carried out to investigate cable dimensional changes during heat treatment and the position of the windings in the coil straight section and in the end region. The analyses allow identifying a set of design changes which, combined with a fine tune of the cable geometry and a field quality optimization, were implemented in a new second-generation coil design. In this paper, we review the main characteristics of the first generation coils, describe the modification in coil layout and discuss their impact on parts design and magnet analysis
Insertion Magnets
Chapter 3 in High-Luminosity Large Hadron Collider (HL-LHC) : Preliminary
Design Report. The Large Hadron Collider (LHC) is one of the largest scientific
instruments ever built. Since opening up a new energy frontier for exploration
in 2010, it has gathered a global user community of about 7,000 scientists
working in fundamental particle physics and the physics of hadronic matter at
extreme temperature and density. To sustain and extend its discovery potential,
the LHC will need a major upgrade in the 2020s. This will increase its
luminosity (rate of collisions) by a factor of five beyond the original design
value and the integrated luminosity (total collisions created) by a factor ten.
The LHC is already a highly complex and exquisitely optimised machine so this
upgrade must be carefully conceived and will require about ten years to
implement. The new configuration, known as High Luminosity LHC (HL-LHC), will
rely on a number of key innovations that push accelerator technology beyond its
present limits. Among these are cutting-edge 11-12 tesla superconducting
magnets, compact superconducting cavities for beam rotation with ultra-precise
phase control, new technology and physical processes for beam collimation and
300 metre-long high-power superconducting links with negligible energy
dissipation. The present document describes the technologies and components
that will be used to realise the project and is intended to serve as the basis
for the detailed engineering design of HL-LHC.Comment: 19 pages, Chapter 3 in High-Luminosity Large Hadron Collider (HL-LHC)
: Preliminary Design Repor
Power Test of the First Two HL-LHC Insertion Quadrupole Magnets Built at CERN
The High-Luminosity project (HL-LHC) of the
CERN Large Hadron Collider (LHC), requires low β* quadrupole
magnets in NbSn technology that will be installed on each side
of the ATLAS and CMS experiments. After a successful shortmodel magnet manufacture and test campaign, the project has
advanced with the production, assembly, and test of full-size 7.15-
m-long magnets. In the last two years, two CERN-built prototypes
(MQXFBP1 and MQXFBP2) have been tested and magnetically
measured at the CERN SM18 test facility. These are the longest
accelerator magnets based on NbSn technology built and tested
to date. In this paper, we present the test and analysis results
of these two magnets, with emphasis on quenches and training,
voltage-current measurements and the quench localization with
voltage taps and a new quench antenna
Persistence of anticancer activity in berry extracts after simulated gastrointestinal digestion and colonic fermentation
Fruit and vegetable consumption is associated at the population level with a protective effect against colorectal cancer. Phenolic compounds, especially abundant in berries, are of interest due to their putative anticancer activity. After consumption, however, phenolic compounds are subject to digestive conditions within the gastrointestinal tract that alter their structures and potentially their function. However, the majority of phenolic compounds are not efficiently absorbed in the small intestine and a substantial portion pass into the colon. We characterized berry extracts (raspberries, strawberries, blackcurrants) produced by in vitro-simulated upper intestinal tract digestion and subsequent fecal fermentation. These extracts and selected individual colonic metabolites were then evaluated for their putative anticancer activities using in vitro models of colorectal cancer, representing the key stages of initiation, promotion and invasion. Over a physiologically-relevant dose range (0–50 µg/ml gallic acid equivalents), the digested and fermented extracts demonstrated significant anti-genotoxic, anti-mutagenic and anti-invasive activity on colonocytes. This work indicates that phenolic compounds from berries undergo considerable structural modifications during their passage through the gastrointestinal tract but their breakdown products and metabolites retain biological activity and can modulate cellular processes associated with colon cancer
Challenges and Lessons Learned from fabrication, testing and analysis of eight MQXFA Low Beta Quadrupole magnets for HL-LHC
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 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
paper, we present a summary of: 1) the fabrication and test data of 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
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Progress on HL-LHC Nb3Sn Magnets
The high-luminosity Large Hadron Collider (HL-LHC) project aims at allowing to increase the collisions in the LHC by a factor of ten in the decade 2025-2035. One essential element is the superconducting magnet around the interaction region points, where the large aperture magnets will be installed to allow to further reduce the beam size in the interaction point. The core of this upgrade is the Nb Sn triplet, made up of 150-mm aperture quadrupoles in the range of 7-8 m. The project is being shared between the European Organization for Nuclear Research and the US Accelerator Upgrade Program, based on the same design, and on the two strand technologies. The project is ending the short model phase, and entering the prototype construction. We will report on the main results of the short model program, including the quench performance and field quality. A second important element is the 11 T dipole that replaces a standard dipole making space for additional collimators. The magnet is also ending the model development and entering the prototype phase. A critical point in the design of this magnet is the large current density, allowing increase of the field from 8 to 11 T with the same coil cross section as in the LHC dipoles. This is also the first two-in-one Nb Sn magnet developed so far. We will report the main results on the test and the critical aspects. 3
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