Applied Physics and Superconducting Technology Directorate

This page describes the Applied Physics and Superconducting Technology Directorate (APS-TD) contribution to LARP. More information can be found at the LARP website: http://www.uslarp.org/.

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  Voltage taps and protection heater leads for Hi-Lumi quadrupoles. Voltage taps help detect quench during magnet testing. Protection heaters uniformly warm the coil so that the stored energy is not deposited in concentrated areas to prevent catastrophic coil destruction.
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  QXF Hi-Lumi quadrupole coil tested in mirror configuration at the Vertical Magnet Test Facility. The mirror structure was developed by the Technical Division to enable quick feedback for design and fabrication.
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  First prototype QXF Hi-Lumi quadrupole magnet being dropped into the Vertical Magnet Test Facility in the Technical Division. Magnet is comprised of two coils wound and cured in the Technical Division and two coils fabricated by CERN.
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  'Accordion' style end part pieces during the assembly of Hi-Lumi LHC Interaction Region quadrupoles. Slots allow each component to conform to the cable shape as shown by the intimate contact with superconducting cable of the inner end part between turns five and six.
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  Assembling four Hi-Lumi LHC quadrupole coils into magnet support structure. Two coils were wound and cured in the Technical Division and two coils were fabricated by CERN. The full magnet structure was cold tested in the Technical Division
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  Winding Hi-Lumi LHC Interaction Region quadrupoles. Coil winding takes place in the Industrial Building Complex of the Technical Division.
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  Cross section of a Hi-Lumi LHC Nb₃Sn quadrupole. Coil was analyzed in the Technical Division for insulation and cable thicknesses and turn displacements.
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  Assembling a Fermilab-built Hi-Lumi coil in a magnetic mirror configuration for testing. The mirror structure was developed by the Technical Division to enable quick feedback for design and fabrication.
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  Preparing a long Hi-Lumi quadrupole coil for transport. Each coil is quality checked within the Technical Division for visual and electrical flaws and for precise size and shape verification.

The US LHC Accelerator Research Program or LARP was initiated in 2003 to develop and protect US investment in accelerator technology through the commissioning, operation, and upgrade of the LHC. For more than a decade the program has developed high-performance Nb₃Sn quadrupoles for interaction region beam focusing. In addition, LARP continues to develop crab cavities for bunch rotating and luminosity leveling as well as wide-band feed back systems for beam instabilities. LARP R&D is predominately focused on the pending Hi-Lumi LHC upgrade where the integrated luminosity is to increase by a factor of 10. Currently LARP leadership is housed in APS-TD.

The LARP collaboration is comprised of four primary member laboratories:

• Fermi National Accelerator Laboratory
• Brookhaven National Laboratory
• Lawrence Berkeley National Laboratory
• Stanford Linear Accelerator Center

Old Dominion University and Jefferson Laboratory also contribute to LARP crab cavity efforts

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Interaction Region Quadrupoles

A key technology for Hi-Lumi LHC are large aperture Nb₃Sn interaction region quadrupoles for final beam focusing. LARP has incrementally and successfully developed 90, 120, and 150 mm aperture quadrupoles using the brittle yet powerful material Nb₃Sn. This development has taken place over the past 10 years with sufficient robustness to enable deployment in the LHC.

APS-TD is heavily involved in the fabrication of the Hi-Lumi LHC Interaction quadrupoles from winding to testing. All prototype coils for the Hi-Lumi upgrade are wound and cured with a ceramic binder for handling in the Industrial Building Complex. The superconductor technology requires a 640°C Nb₃Sn formation heat treatment and subsequent epoxy impregnation accomplished by APS-TD. After four coils are assembled and preloaded into a magnetic flux return, the full magnet structure is cold tested within APS-TD’s test facility.

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Crab Cavities

Beams of particles cross at slight angles when they collide which reduce the collision rate for typical particle colliders. To increase the number of collisions and thus the luminosity each beam bunch can be slightly rotated increasing the cross sectional area. In Hi-Lumi LHC this rotation will be achieved by superconducting RF Crab cavities. Crab cavities are under development in APS-TD for ‘kicking’ the nose and tail of each bunch in opposite directions to maxim the luminosity increase for Hi-Lumi LHC.