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US-LHC Activities in AD

US-LHC Activities in AD. Tanaji Sen. Overview. The LHC US-LHC Construction Project US-LARP Goals and Activities Accelerator Physics Instrumentation Beam Commissioning LHC@FNAL. The wise speak only of what they know Gandalf, Lord of the Rings.

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US-LHC Activities in AD

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  1. US-LHC Activities in AD Tanaji Sen

  2. Overview • The LHC • US-LHC Construction Project • US-LARP Goals and Activities • Accelerator Physics • Instrumentation • Beam Commissioning • LHC@FNAL The wise speak only of what they know Gandalf, Lord of the Rings

  3. LHC Control Room

  4. Key Parameters

  5. US-LHC Construction Project • Interaction Region Quads (FNAL) • Interaction Region Dipoles (BNL) • Interaction Region Cryogenic Feedboxes (LBL) • Interaction Region Absorbers (LBL) • Accelerator Physics (FNAL, BNL, LBL) - related to IR designs and magnets - ecloud, noise effects Last magnets to be delivered in 2006

  6. MBXA CORR MQXA CORR MQXB CORR MQXB CORR MQXA DFBX TAS “D1” “Q3” “Q2” “Q1” FNAL BNL LBNL CERN KEK LHC IR Quads at FNAL FNAL quads To IP 1st IR quad ready for shipment in May 2004 • FNAL is delivering 18 • IR quads to the LHC • All IR quads (FNAL, KEK) are cryostatted at FNAL • and shipped from here • Last quad to be shipped in late 2006.

  7. FNAL quads installed in IR8 Mission Accomplished ? Courtesy: J. Kerby

  8. US- LARP Goals – stated by J. Strait (2002) • Extend and improve the performance of the LHC so as to maximize its scientific output in support of US-CMS and US-ATLAS • Maintain and develop the US labs capabilities so that the US can be the leader in the next generation of hadron colliders. • Serve as a vehicle for US accelerator physicists to pursue their research • Train future generations of accelerator physicists. • It is the next step in international cooperation on large accelerators. Fermilab has been appointed the “Host Laboratory” to lead this program.

  9. US LARP Institutions Two main areas: • High field magnets • Accelerator systems Accelerator Physics, Instrumentation, Collimation, Commissioning (beam & hardware) • High field magnets: BNL, FNAL, LBL • Accelerator Physics: BNL, FNAL, LBL • Instrumentation: BNL, FNAL, LBL, UT Austin • Collimation: SLAC • Commissioning: BNL, FNAL, LBL

  10. US-LARP Goals • Accelerator Physics and Experiments - understand performance limitations of current IRs and develop new designs - Beam dynamics calculations and related experiments • Develop high performance magnets for new higher luminosity IRs - large-aperture, high gradient quadrupoles using Nb3Sn - high field beam separation dipoles and strong correctors • Develop advanced beam diagnostics and instrumentation - luminosity monitor, tune feedback, Schottky monitor, rotatable collimators - other systems as needed for improving LHC performance • Commissioning - participate in the sector test and LHC beam commissioning - commission hardware delivered by the US

  11. IR Upgrade

  12. Luminosity and IR upgrade J. Strait • An IR upgrade is a straightforward way to increase the luminosity – by a factor of 2-3 • It must also deal with higher beam currents and 10 times larger debris power at L=1035cm-2s-1 • Several optics design issues • ~50% of LARP effort is in IR magnet design A luminosity upgrade will be required around ~2015 to keep the LHC physics program productive.

  13. Quadrupoles 1st option Advantages • Allows smaller β*, minimizes aberrations. • Lower accumulation of charged particle debris from the IP. • Operational experience from the first years of running. Disadvantages • More parasitic beam-beam interactions. • Crossing angle has to increase as 1/√β* • IR correction systems act on both beams simultaneously Baseline Design

  14. Dipoles 1st – 2 options Advantages • Fewer parasitic interactions. • Correction systems act on single beams. • No feed-down effects in the quads Disadvantages • Large energy deposition in the dipoles. • Beta functions are larger → increases aberrations. • Longer R&D time for dipoles • Longer commissioning time after the upgrade. Triplets Doublets

  15. Optics Solutions βMax = 9 km Quads first LARP magnet program aims to build 15T pole tip fields βMax = 27 km βMax = 25 km Dipoles first: triplets Dipoles first: doublets J. Johnstone, TS

  16. IR Design Issues→ Luminosity Reach • Requirements on magnet fields and apertures • Optically matched designs at all stages • Energy deposition • Beam-beam interactions • Chromaticity and non-linear correctors, field quality • Dispersion correction • Susceptibility to noise, misalignment, ground motion; emittance growth • Closest approach of magnets to the IP (L*) • Impact of Nb3Sn magnets, e.g flux jumps • R&D time required to develop the most critical hardware and to integrate it in the LHC • ….. All need to be considered in defining the luminosity reach

  17. Towards a Reference Baseline Design Proposal by F. Ruggiero (CERN) • “Define a Baseline, i.e. a forward looking configuration which we are reasonably confident can achieve the required LHC luminosity performance and can be used to give an accurate cost estimate by mid-end 2006 in a Reference Design Report • Identify Alternative Configurations • Identify R&D to - support the baseline - develop the alternatives” Separately, the LARP magnet program has been tasked to deliver a working prototype of a Nb3Sn quadrupole by 2009.

  18. Wire Compensation of beam-beam interactions

  19. Long-range interactions • Long-range beam-beam interactions are expected to affect LHC performance – based on Tevatron observations and LHC simulations • Wire compensator is proposed to mitigate their impact • RHIC has a 2 ring layout like the LHC – can be used to test the principle Difference in kicks between a round beam and a wire < 1% beyond 3 sigma

  20. Wire compensation in RHIC and LHC LHC RHIC IP IP6 Reservedfor wire compensators Location of wire compensators Installation in Summer 2006 To be installed if required to improve performance. Feasibility would determine upgrade path

  21. RHIC beam-beam experiments • Motivation for experiments: Test of wire compensation in 2007 Determine if a single parasitic causes beam losses that need to be compensated Experiments in 2005 and 2006 Remote participation at FNAL via logbook • Motivation for simulations: Tests and improvements of codes, predictions of observations in 2006 and of wire compensation Several groups: FNAL, SLAC, LBL, University of Kansas (coordinated at FNAL) Website: http://www-ap.fnal.gov/~tsen/RHIC

  22. Beam-beam Experiments and Simulations (2006) Simulated lifetimes show a linear dependence on the beam separation FNAL Simulations • Beam lifetime responds to vertical separation but vertical separation  4σ (1st study – April 5th, 2006) • 4 studies in all (April-May) to explore larger separations and tune space • Analysis to find dependence on beam separation in progress V. Ranjbar, TS

  23. Wire Compensator in RHIC • 1 unit in each ring • 2.5m long • Currents between 3.8 – 50 A • Vertically movable over 65mm • Install in Summer 2006

  24. Pulsed Wires • Required for bunch to bunch compensation – PACMAN bunches • Challenges are the high pulse rate and turn to turn stability tolerances LHC bunch pattern Pulse pattern Open Design Challenge

  25. Energy Deposition

  26. Energy deposition • Primary source of radiation in the IR magnets: pp collisions, ~ Luminosity Tevatron: debris power ~ 2 W LHC at 1035cm-2s-1, debris power ~ 9kW • Energy deposition is viewed as the major constraint on the IR upgrade Could be key in deciding between quads first or dipoles first. • Other sources include operational beam losses (e.g. beam gas scattering) and accidental losses (e.g. misfiring of abort kickers)

  27. Energy Deposition Issues & Constraints • Quench stability→ Peak power density Require Epeak to be below the quench limit by a factor of 3 • Magnet lifetime → peak radiation dose and lifetime limits for various materials Baseline LHC: expect lifetime ~ 7 years for IR magnets Upgrade LHC: requires new radiation hard materials • Dynamic heat loads → Power dissipation and cryogenic implications Require heat load < 10 W/m • Residual dose rates → hands on maintenance Require residual dose rates < 0.1 mSv/hr • Dedicated system of charged particle and neutral absorbers in the IRs

  28. Energy Deposition: Open Mid-plane Dipole • ED issues constrain the dipole design to have no coils in the mid-plane • Εpeakin SC coils ~0.4mW/g, below the quench limit • Estimated lifetime based on displacements per atom is ~10 years • Dipole design will require significant R&D, further LARP design work postponed R. Gupta (BNL) N. Mokhov

  29. Quadrupole first design • Without mitigation, Epeak > 4 mW/g. Target value is ~1.7mW/g • Mitigation by thick inner liner • Stainless steel liners are not adequate • Thick Tungsten-Rhenium liner reduces Epeak ~ 1.2 mW/g I. Rakhno

  30. Tertiary Collimators • Designed to protect the detector and IR components from operational and accidental beam losses Similar collimator used at A48 in the Tevatron to protect against abort kicker misfire For the LHC propose 1m long Tungsten or Copper collimator upstream of neutral absorber To IP N. Mokhov

  31. LHC Injector

  32. LHC Injector in the LHC tunnel • Injector will accelerate beams from 0.45TeV to ~1.5TeV - Field quality of LHC better at 1.5GeV - Space charge effects lower, may allow higher intensity bunches - Could allow easier transition to LHC doubler • The injector will be installed in the LHC tunnel during scheduled LHC shutdowns • Return to the standard SPS injection into the LHC will be possible • The main magnets will be the type of super-ferric combined function magnets proposed for the VLHC I. H. Piekarz (TD)

  33. LHC Injector (LER) Vertical distance between LER and LHC beams is 1.35m VLHC low-field magnet 0.6 T (injection) → 1.6 T

  34. Beam Transfer Fast pulsing magnets (PM) have to be turned off within 3 micro-secs after LHC is filled. CERN Workshop October 2006 Sequence: SPS-> Injector -> LHC --- what is not surrounded by uncertainty cannot be the truth R.P. Feynman

  35. Instrumentation • Schottky Monitor • Tune and Chromaticity Feedback • New Initiatives

  36. Schottky Monitor at the Tevatron Allows measurements of: • Tunes from peak positions • Momentum spread from average width • Beam-beam tune spread of pbars • Chromaticity from differential width • Emittance from average band power

  37. Schottky Monitor Design Schottky Monitor will provide unique capabilities • Only tune measurement during the store • Bunch-by-bunch measurement of parameters such as Tune, Chromaticity • Average measurements as well • Momentum spread & emittance • Non invasive Technique • Diagnosis of beam-beam effects and electron cloud R. Pasquinelli, A. Jansson 4 Monitors to be installed in the LHC, Summer 2006

  38. Tune and Chromaticity feedback Goals • Control the tune during the acceleration ramp to avoid beam loss • Control the chromaticity during the snapback at start of ramp • PLL method: excite the beam close to the tune and observe the resonant beam transfer function • Then used in a feedback system to regulate the quadrupole current and tune Measurement in RHIC with tune feedback – tune changes ~ 0.001

  39. Tune & chromaticity at the Tevatron Phase Modulation Off • The Direct Diode Detection method (3D BBQ) from CERN implemented in the Tevatron – complements tune measurements from the Schottky monitors. More sensitive than the Schottky. • This 3D BBQ has been used to measure the chromaticity with a method due to D. McGinnis. • Interest in implementing this method at RHIC and the SPS Phase Modulation On C.Y. Tan

  40. New FNAL Initiatives - proposed • AC Dipole (A. Jansson) • Electron lens compensation of head-on interactions (V. Shiltsev) • Crystal collimation (N. Mokhov) • Measure field fluctuations in magnets (V. Shiltsev)

  41. Commissioning • LHC Plans • LARP involvement • LHC@FNAL

  42. LHC Commissioning Plan Stage I II III IV No beam Beam Beam • I. Pilot physics run • First collisions • 43 bunches, no crossing angle, no squeeze, moderate intensities • Push performance (156 bunches, partial squeeze in 1 and 5, push intensity) • Performance limit 1032 cm-2 s-1 (event pileup) • II. 75ns operation • Establish multi-bunch operation, moderate intensities • Relaxed machine parameters (squeeze and crossing angle) • Push squeeze and crossing angle • Performance limit 1033 cm-2 s-1 (event pileup) • III. 25ns operation I • Nominal crossing angle • Push squeeze • Increase intensity to 50% nominal Performance limit 2 1033 cm-2 s-1 • IV. 25ns operation II • Push towards nominal performance • R. Bailey (CERN)

  43. Expression of Interest Form In anticipation of LHC-related studies using the SPS in the coming months and commissioning next year, LARP is soliciting interest for involvement in same. http://larp.fnal.gov/commissioningForm.html is the link for you to register your interest in being part of this effort. Please respond to Elvin Harms by June 1st

  44. SPS studies – test LHC issues • LHCcollimatortests • LSS6 commissioning • TI8 extraction test • LSS4/LSS6 interleaved • LHC beam lifetime • LHC orbit feedback • BBLR – beam-beam compensation • LHC BLM tests in the PSB --- sample of studies planned From G. Arduini (CERN)

  45. LARP plans for Beam Commissioning • Refining areas of involvement, identifying CERN counterparts ~15 people signed up (across all 4 labs) • LARP presence during SPS run in Summer ’06 3 FNAL people participating, room for a few more • Sector test presence planned About 2 weeks, late 2006 – early 2007 • Software effort In support of instruments and control room here • Planning for long-term visits during LHC commissioning E. Harms

  46. What is LHC@FNAL? • A Place • That provides access to information in a manner that is similar to what is available in control rooms at CERN • Where members of the LHC community can participate remotely in CMS and LHC activities • A Communications Conduit • Between CERN and members of the LHC community located in North America • LARP use: Training before visiting CERN, Participating in Machine Studies, Analysis of performance, “Service after the Sale” of US deliverables • An Outreach tool • Visitors will be able to see current LHC activities • Visitors will be able to see how future international projects in particle physics can benefit from active participation in projects at remote locations. Planned Opening in September 2006 E. Gottschalk

  47. LHC@FNAL You can observe a lot just by watching Yogi Berra

  48. Control Room at CERN 13 operators on shift + experts Started operation on Feb 1, 2006

  49. LHC Challenges • Machine protection • Quench protection e.g at 7 TeV, fast losses < 0.0005% bunch intensity • Collimation (400 degrees of freedom!) • Controlling 2808 bunches • Snapback and ramp ΔQ’ (snapback) ~ 90, ΔQ’ (ramp & squeeze) ~ 320 • -----

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