SLAC Accelerator Development Program LHC Accelerator Research

SLAC Accelerator Development ProgramLHC Accelerator Research

Tom Markiewicz

OHEP Accelerator Development ReviewJanuary 24-26, 2011

LHC Accelerator Research at SLACProgram 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

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


Task People DescriptionRotatable Collimators

G. Anzalone, Lew Keller, R. Rogers, S. Lundgren, T. Markiewicz, Jeff Smith, Liling Xiao + KLY+MFD

Prototype RCs to CERN to test in SPS, HiRadMat Test Facility & LHC for LHC Phase II Collimation Upgrade

LHC LLRF John Fox , Claudio Rivetta, Themis Mastorides, Dan van Winkle

Adapt PEP-II LLRF Tools to LHC & Use for System Configuration, Study & Improvement

Feedback to control Ecloud in SPS

John Fox, A. Bullitt, O. Turgut, T. Mastorides, C. Rivetta, J. Olson

Studies of FB to control Electron Cloud & TMC Instabilities in the SPS

SPS Vacuum Ch tocontrol Ecloud

Mauro Pivi Ecloud Remediation via Grooved & Coated Vacuum Chambers

Long Term Vistors Alan FisherUli Wienands

LHC Synchrotron Light MonitorLHC Commissioning, PS2 Planning & UA9

LHC Crab Cavity Zenghai Li, Liling Xiao Crab Cavity Studies

Crystal Collimation Tom Markiewicz, Bob Noble, Marco Oriunno, U. Wienands

Crystal Collimation experiments at SPS and LHC & future e-,e+ tests at SLAC

PS2 Studies U. Wienands, K. Bane, Lanfa Wang, Cho Ng, C. Rivetta, G. Stupakov

Write “Collective Effects” sections of CERN White Paper for PS2 design

LHC Accelerator Research Program Reference Table

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


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


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 2009-2010:1. 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


LHC LLRF and Longitudinal Beam DynamicsResults Continued

2. 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 the formalism 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.

3. 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.


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:1. 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

2. Modelling and dynamics 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


SPS Wideband Transverse Electron Cloud/TMCI Feedback

3.Development of linear coupled-oscillator model of internal bunch dynamics in progress– Use this to explore alternate feedback designs

4. 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


LHC Crab CavityPurpose: Develop crab cavity and coupler designs consistent with

gradient, frequency and spatial contsraints of the LHCResults: 1. 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


LHC Crab Cavity2. 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


UA9 Crystal Collimation Experiment at SPSPurpose: Extend core expertise in collimation of intense beams to crystal based

primary collimators by participating in UA9 SPS crystal collimation experimentResults:• SLAC Built Roman Pot: will house tracking detectors

– LARP M&S, GAD Engineering• LTV U. Wienands central to 2010 experimental program


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


LTV: LHC Synchrotron Light MonitorLTV 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


LTV: LHC Synchrotron Light MonitorImpact:

– 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


SLM in Abort Gap Cleaning Test

Past Funding and Future Needs


FY 2008 2009 2010 2011Funding (k$) N/A 995 961 142

• 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

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


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 LHC Accelerator Research

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