SLAC Accelerator Development Program LHC Accelerator Research

1. SLAC Accelerator Development ProgramLHC Accelerator Research Tom Markiewicz OHEP Accelerator Development Review January 24-26, 2011

2. LHC Accelerator Research at SLAC Program began with a small LARP collimation task in 2003. Now: • 8-9 areas of R&D & 2 year-long “Long Term Visitors” to CERN • ~17 physicists, 4 MEs, 3 Ph.D. students, 1 postdoc + KLY + MFD • 1 Ph.D. awarded → LARP Toohig Fellow • Leadership in US LARP & strong collaboration w/US labs + CERN • LARP Deputy Leader, Accel Systems Manager, Toohig Chairman, …. • Early LARP funded work expanded in FY08 with LARP call for “New Initiatives” to topics synergistic to SLAC’s traditional core skills and expertise • RF control, Electron Cloud studies, Feedback control, EM and beam physics calculations, collective effects, high intensity beam control,.. • GAD funding was used to develop these programs to the point where LARP would fund the effort SLAC Accelerator Development Program Page 2

3. LHC Accelerator Research Tasks • Tasks funded solely by LARP • Design & prototype a collimator for LHC’s collimation upgrade • Write Collective Effects sections of PS2 Design Report • New tasks with seed funding from SLAC GAD for labor with Travel & M&S from LARP, transitioning to ~full LARP support • LHC Low Level RF • Feedback Control of Electron Cloud and Transverse Mode Coupled Instabilities in the SPS • LHC Crab Cavity Design • UA9 Crystal Collimation Experimentation in the SPS and LHC • Support of SLAC LTVs in LARP’s “Long Term Visitor Program” • Synchrotron Light Monitor, Crystal Collimation, PS2 Studies, LHC Beam Commissioning • Future tasks under discussion • Beam Physics Group involvement in HL-LHC Project • Role in any new LHC Hardware “Project” funded by DOE • Crab, Collimation, Injectors have been discussed SLAC Accelerator Development Program Page 3

4. LHC Accelerator Research Program Reference Table

5. Project Management • At onset, each GAD-seeded task at SLAC was • Ranked highly by CERN’s liaison to LARP • Approved by the LARP Accelerator Systems Advisory Committee • Blessed by the LARP Advisory Board • Progress is monitored through regular team work meetings • Reporting occurs regularly at • Biannual LARP Collaboration meetings • Biannual DOE reviews of LARP • Numerous CERN, EuCARD, PAC/IPAC, special topic meetings,… • Results are documented • 3 Refereed Journals (PRSTAB, PL) • 17 Conference Proceedings • 4 CERN Reports SLAC Accelerator Development Program Page 5

6. Goals and Mission Relevance • Overall • SLAC participation in a project at the ENERGY frontier • Extend SLAC’s core competencies to high current proton beams • Improve LHC performance to advance science • Relevance: Tasks are integral part CERN plan • Regular emails from P. Baudenghein (BE-RF) praising LLRF work • SPS HF Transverse FB Proposal (W. Hoefle, E. Ciapella) • “It is believed that this system can be built with strong support from US labs (SLAC/LBNL).” • Letters from S.Myers/R. Heuer to DOE on Upgrade Plans: • Crab cavities, SPS HF Feedback, Collimation HIGH on priority list • HL-LHC Project Work packages explicitly incorporate SLAC work • SLAC Compact crab cavity one of 3 options • SLAC Elliptical cavity is only fallback option • Letters from LHCC requesting UA9 Crystal Collimation tests in LHC when ready SLAC Accelerator Development Program Page 6

7. LHC LLRF and Longitudinal Beam Dynamics Purpose: LHC non-linear beam dynamics-RF station simulation and system model. • The model captures engineering level implementation details. Results in 2009-2010: • The LLRF configuration tools have been used by the CERN BE-RF group to remotely commission the LLRF feedback loops of the RF stations during start up in both November 09 / February 10. • Tools reduced commissioning from 1.5 days/station to 1.5 hours/station. • Model based configuration adds consistency and reliability. • CERN BE-RF group have repeatedly expressed their support and proposes • Continue work to test the 1-turn feedback functionality of the commissioning tools • Expansion of the tools to control the smooth increase of the High Voltage and Klystron current with beam, from 450 GeV conditions to ramping/physics SLAC Accelerator Development Program Page 7

8. LHC LLRF and Longitudinal Beam DynamicsResults Continued • RF Noise Effect on Beam Diffusion Studies • Developed theoretical formalism relating the equilibrium bunch length with beam dynamics, accelerating voltage noise, and RF system configurations. • Conducted measurements that • confirmed theformalism and models • identified performance-limiting components • RF reference noise introduced by controller in mod/demodulation process • Intrinsic noise in the controller feedback boards • set an allowable noise threshold for acceptable lifetime. • Predictions of beam longitudinal motion and RF station stability limits for future high current/higher energy LHC operations • Estimated longitudinal stability margin for 2011 operations. • Impact of future LLRF configurations on RF noise levels is being investigated. SLAC Accelerator Development Program Page 8

9. SPS Wideband Transverse Electron Cloud/TMCI Feedback Purpose: control Ecloud and TMCI effects in SPS via GHz bandwidth feedback • Technical formalism similar to 500 Ms/sec feedback implemented at PEP-II, KEKB, DAFNE • CERN, LBNL, SLAC (2 current, 1 graduated Stanford students+ staff) Approach & Results: • Measure electron cloud & TMCI vertical instabilities in SPS during Machine Development periods in 2009 and 2010 • Instability dynamics • Response of beam to driven motion • Pickup and kicker studies using existing hardware • Modelling anddynamics estimation • Validation of LBNL Warp and Head-Tail models by comparisons to MD results • simulations critical in estimating future conditions • Model dynamics of driven and free beam motion SLAC Accelerator Development Program Page 9

10. SPS Wideband Transverse Electron Cloud/TMCI Feedback • Development of linear coupled-oscillator model of internal bunch dynamics in progress • Use this to explore alternate feedback designs • Development of a “small prototype” functional feedback channel in progress a 4 GS/sec. beam excitation system for SPS • Modify existing SPS kicker system to synchronize with selected bunches • Use 4 Gs/sec. DAC hardware to drive noise sequences onto selected bunches • Use in 2011 MD periods Ongoing & Future • Identify critical technology options • Evaluate difficulty of technical implementation • Work toward “full prototype” for installation in next long down, then eventual final system SLAC Accelerator Development Program Page 10

11. LHC Crab Cavity Purpose: Develop crab cavity and coupler designs consistent with gradient, frequency and spatial contsraints of the LHC Results: • 800 MHz Elliptical Cavity • 2009 CERN CC Collaboration Baseline • “Global Crab Scheme”: • One cavity per beam located in IR4 RF area • Fully studied • Modes, fields, R/Q, multipacting • basic and alternative coupler designs • Stays as backup solution in HL-LHC Crab Cavity WP SLAC Accelerator Development Program Page 11

12. LHC Crab Cavity • 400 MHz Half Wave Spoke Resonator Cavity • Designed for “Local Crab Scheme” • One per beam per side per IR • Fully studied • Modes, fields, impedance, R/Q, multipacting • Basis of AES, Inc. SBIR & Engineering Study • One of several designs in HL-LHC Crab Cavity WP SLAC Accelerator Development Program Page 12

13. UA9 Crystal Collimation Experiment at SPS Purpose: Extend core expertise in collimation of intense beams to crystal based primary collimators by participating in UA9 SPS crystal collimation experiment Results: • SLAC Built Roman Pot: will house tracking detectors • LARP M&S, GAD Engineering • LTV U. Wienands central to 2010 experimental program SLAC Accelerator Development Program Page 13

14. UA9 Crystal Collimation Experiment at SPS • Preliminary results of Sept 2010 Run (to be sub. To Phys.Lett.) • Reduction of particle losses due to inelastic nuclear interactions of x35 • Future • 2011 runs in SPS • Planning for LHC experiment • Investigation with e-, e+ beams at FACET for collimation and as photon source SLAC Accelerator Development Program Page 14

15. LTV: LHC Synchrotron Light Monitor LTV Purpose: Educate & invigorate staff with challenges at the energy frontier while transferring knowledge to CERN • The SLM activity was a serendipitous result of 2009 “Long Term Visit” by A. Fisher after 2008 tunnel cryo-explosion • Given startup pressures there was still much set up of SLM needed Results • In 2009 identify limitations in hardware, modify setup, test, etc. • In 2010 commission SLM with beam • In routine use for observing beam size at injection, ramp, 3.5 TeV • Light from Lead Ions observed • In routine use for monitoring abort gap SLAC Accelerator Development Program Page 15

16. LTV: LHC Synchrotron Light Monitor SLM in Abort Gap Cleaning Test Impact: • Perhaps the most cost-effective contribution of LARP to CERN • Many complements (Bravin, Bruning, Myers) & hopes for continued involvement Future • Continued participation in further commissioning • Improve agreement with wire scanners, longitudinal density monitor, .. • Possible development of a Digital Mirror Array based halo monitor at SSRL for LHC SLAC Accelerator Development Program Page 16

17. Past Funding and Future Needs SLAC Accelerator Development Program Page 17 • Program has transitioned to majority support by US LARP • 2011 supports 50% of students and token fractions of staff • Discussions with LARP underway on: • Proposal again is for ~1year of transition funding from SLAC GAD then LARP • Beam Physics Group involvement in HL-LHC Project (~1 FTE) • Response to CERN requests for more FTEs for Crab Cavity Design (~ 0.8 FTE) • New LTV requests will be considered on case by case basis • LARP rules preclude salary support for senior LTVs

18. Collaboration and Technology Transfer Collaboration • LARP Labs (BNL, FNAL, LBNL) and CERN • Crab Cavity Collaboration (above & CEA, KEK, CNRS, STFC, U. Lancaster) • UA9 Collaboration (above & Imperial College, INFN, IHEP, JINR, PNPI) • Advanced Energy Systems, Medford NY Technology Transfer • LLRF Tools, SLM expertise, High Bandwidth Feedback expertise & hardware, Roman Pots, Specific Crab cavity Designs to CERN • Compact Crab Cavity design to AES SLAC Accelerator Development Program Page 18

19. Summary • All programs presented are • part of CERN’s accepted operational model or are in CERN’s documented upgrade plans • Reviewed regularly by DOE as part of LARP • GAD funding has been a well leveraged & cost effective • We can do more with more funding • LARP cannot fund all requests it receives SLAC Accelerator Development Program Page 19