Summary of Accelerator Systems New Initiatives Parallel Session

Summary of Accelerator Systems New Initiatives Parallel Session

19 October 2007

LARP CM#9 - SLAC

Tom Markiewicz/SLAC

BNL - FNAL- LBNL - SLAC

US LHC Accelerator Research Program

LARP CM9 - 19 October 2007 New Initiatives Summary - T. MarkiewiczSlide n° 2 / 8

10 New Initiatives-Thursday 1:30PM

While money is always tight and FY08 in particular has been allocated with little wiggle room, consensus is that we try to improve LARP system to:

•Introduce projects early enough to get input from relevant parties: lab partners, CERN, home institution

•Consider how to have LARP manage, or incubate, LHC projects taken on as part of the lab’s base program

•Give management more time to request new monies and/or manage existing funds

Start Time End Speaker Title13:30 0:15 13:45 T. Markiewicz FY08 Top-Down Budget Constraints on New Initiatives13:45 0:15 14:00 N. Mokhov Material Irradiation Studies at BNL and FNAL14:00 0:15 14:15 Y. Yan LHC optics measurement, modeling, and correction14:15 0:15 14:30 K. Bane Impedance & Stability at LHC14:30 0:15 14:45 A. Fischer LHC synchrotron light monitors, BLMs and Luminosity Feedback14:45 0:09 14:54 U. Wielands LHC remote control @ SLAC14:54 0:06 15:00 W. Wittmer Phase Advance Data Analysis15:00 0:15 15:15 Y. Cai Study of beam-beam limit in hadron machines15:15 0:15 15:30 T. Sen Optical Diffraction Radiation in Tevatron & LHC Proposal15:30 0:15 15:45 J. Fox LLRF Studies at LHC15:45 0:15 16:00 J. Fox Studies of the electron cloud instability in the SPS


Irradiation Damage in LHC Beam Collimating Materials

N. Simos (BNL) & N. Mokhov (FNAL)Request:

– Fund a CONTINUING EFFORT in irradiation studies• 0.3 BNL senior FTE/year plus $180k/year for beam time

– Funding requested for FY08, FY09, FY10

Deliverables:– Continued studies of physical properties of already irradiated

Phase I and Phase II materials– Extension of materials to

• Exotic composites (Diamond-Metal, Carbon-NanoFiber-Cu, etc.)• SC Magnet Materials• Crystals

– Neutron & Gamma studies of materials– Study of physical properties as function of radiation dose– integrated software package (MARS + Non-linear structural

dynamics code) for reliable prediction of radiation effects, benchmarked in dedicated measurements

– Laser-based shock (high-strain rate) effects on irradiated materials


LHC optics measurement, modeling, and correction with Model Independent Analysis (MIA)

Yiton Yan (SLAC)

Description:

MIA is a series of MATLAB programs that has been proven robust for PEP-II optics correction.

MIA, via an analysis of turn-by-turn BPM orbit data and an auto SVD-enhanced fitting process, brings the real hardware storage ring to a computer -- the virtual machine that matches the real machine in optics.

MIA then figures out a better virtual machine (lower beta beat, lower coupling, lower dispersion beat, etc) for the real machine to emulate and calculates tuning “knobs” to change real machine to the model

MIA has helped PEP-II overcome many optics improvement milestones and has had major contributions for PEP-II luminosity enhancement.

Goals:• Adapt MIA to LHC• Strong synergy with AC Dipole program


MIA Resource Request

Manpower• Y. Yan: ½ FTE both for FY 2008 and FY 2009.

Travel• 2 trips to BNL in FY2008• LTV (3 month) visit to CERN at machine startup• LTV (6 month) visit to CERN in 2009

Deliverables:• Modify MIA for LHC

– Identify BPM problems via MIA analysis of LHC optics at startup– Develop LHC optics model and start LHC optics improvement

(beta beat and coupling correction, etc.) with MIA (2009 goal)• Modify MIA for RHIC and benchmark at RHIC at BNL• Long term future of continued study of LHC optics via MIA at SLAC

with occasional visits as required


Impedance and Stability at the LHCKarl Bane (SLAC)

to build on what CERN has already done, and to collaborate with

them on solving impedance/instability questions for the LHC

preliminary goal: try to understand SPS impedance/measurements;

eventually work to LHC

to commit to 0.5 FTE in 2008

I would go for 3 months to CERN

the other 3 months would be done by me and/or others, working

here and/or at CERN

others expressing interest in participating – Z. Li, C. Ng, R. Warnock,

S. Heifets, G. Stupakov, …

it is envisioned that this work would continue past 2008


Proposed Impedance Tasks

LHC• collimator impedance calculations, low frequency resistive wall

impedance questions (RA, EM)• complete impedance budget – to get realistic impedance of ring (FZ)• stability simulations – longitudinal, transverse; macroparticle,

linearized Vlasov, etc; simulate experiments with feedback (EM)• clearing efficiency of collimators when including wakefields; puzzle of 10 second tails in scraping tests (FZ, RA)• effect of impedance on Landau damping (FZ) • impedance measurements planning (FZ) • coupled bunch instabilities at LHC – participate in shifts (EM)SPS:• puzzle in longitudinal and transverse impedance measurements (EM)• fast vertical single bunch instability at injection (EM)• simulations -- compare with measurements (ES) LHC upgrade:• intensity limits (FZ)


Synchrotron-Light Monitors,Beam-Loss Monitors,

Luminosity Dither FeedbackAlan Fisher (SLAC)

SLM Collaboration– Hutchins is very interested in having an experienced SLM person

to devise and execute a detailed commissioning procedure.• The remote control room at SLAC then allows an expert in a different

time zone to respond to concerns from the CERN control room.

– Collaboration on the future capabilities may follow.

BLMs– Dehning was very interested in having an outside look at their

evaluation of system reliability.• He asked me to read a 2005 PhD thesis on the reliability of the BLM

system. I have done so and have begun discussing details with him.

– This is likely to lead to further collaboration as the system is commissioned.


Instrumentation Commissioning (continued)

Luminosity Monitor Dithered Feedback– Bill Turner of LBNL originally intended a dither for LHC using their

luminosity monitor.– As an LHC upgrade we return to this idea, proposing a feedback based on

PEP’s scheme.• To begin: which magnets and power supplies are suitable?

– Participants: Fisher, Wienands, Sullivan (SLAC); Turner, Ratti, Matis (LBNL); Kozanecki (Saclay)

Budget (for SLAC/LARP only) • depends on LHC commissioning and on coordination with CERN.

– FY 2008• %FTE: 5%• Travel: 5 k$

– One trip for 1 to 2 weeks– FY 2009

• %FTE: 40%– Long-term visitor program

• Travel: 10 k$– 2 trips in addition to LTV


LHC Remote Control Area at SLAC


Analysis of Phase-Advance DataWalter Wittmer (SLAC)

At PEP-II, phase-advance data is used routinely to assess state of the optics (ß beat, coupling)– Turn-by-turn, 1024 turns, for each BPM– Phase and amplitude extraction in RInQ BPM processors.– Extract ß functions by comparison with model

• LHC will have an AC Dipole & can take similar data

• The tricky part:

– Dealing with 90°/cell (per BPM) phase advance• (Wienands et al., EPAC 2002)

– Dealing with imperfect data (noise, non-reading BPM, ...)

• At PEP-II this is packaged in the online system

– Fortran/C, Oktave (Matlab) prototype exists also.


Phase Advance Measurement Proposal

• Visit (in FY08) to CERN by Wittmer

– Explore possibility of bringing our software to LHC

– Explore possibility of collaborating with Fartoukh &Tomas to apply their methods to PEP-II

• $3k in FY08 for this visit

• Follow-on Request for FY09 to be presented at next CM.

– Actual software port & installation.

• BNL / Fermilab has an AC-Dipole effort in LARP. We would like to explore joining with them.


Study of Beam-Beam Limit in Hadron CollidersYunhai Cai and Robert Warnock (SLAC)

Beam-Beam lifetime (T. Sen, A. Kabel )

Parasitic collision

Wire compensation (W. Fischer)

Electron lens compensation (V. Shiltsev)

Emittance growth due to beam-beam collisions

Strong-weak, gives too small values

Strong-strongGives unreliable values due the numerical noise

Predicts a beam-beam limit that is a factor of ten larger than in the electron machine


Improving Strong-Strong Codes

• Numerical noise in PIC codes– Macro particle representation of density– Discrete Poisson solver

• Vlasov-Poisson approach to eliminate the noise due to macro particles– 1D code for microwave instabilities was proven very effective– 2D beam-beam code was developed by Andrey Sobol. Ported– to computers at SLAC

• A new idea to solve Vlasov, with some advantages of PIC method (lower cost , while keeping low noise)– Forward tracking (similar to macro particles)– Smoothing by interpolation of data at quasi-random sites– Probability conserving algorithm at data sites


Goal and Plan

• Compare noise between PIC and Vlasov codes and quantify any improvements

• To understand emittance growth due to beam-beam in hadron machines at least in relative terms within two years

• Benchmark the codes against experiments in Tevatron and RHIC, understand the emittance growth at 10% level within five years and compare to the result from LHC

• Resource: – 2 FTE for two years possible extension to five years– At least one new FTE (post-doctoral)– Maybe a dedicated cluster later


Optical Diffraction Radiation Monitor

Radiation emitted when a charged particle passes in the vicinity of a conducting target.– Two cones (angle ~ 2/γ ) of radiation in the forward and backward direction– Key parameters: the impact parameter, beam energy and wavelength of

radiation– Main advantage: Non-invasive

Observables– Near field (at or near target) intensity– Polarization– Frequency spectrum– Far field angular distribution– Interference

Extract– Beam size– Beam position– Beam divergence– Energy

Beam

FDR

BDR


Optical Diffraction Radiation Pre-ProposalTanaji Sen - Fermilab

• Design ODR setup in the Tevatron – E0 preferable. • Develop a collaboration with US labs and CERN• Present proposal to the LARP collaboration for

funding a LARP task (April 2008)• Proceed with experiments • Develop ODR facility for the LHC• Determine potential for future machines: muon

collider, ILC,…


LLRF system - Beam dynamics models for LHCImpedance Control Architectures, Effects of technical

implementation on accelerator performanceJ.D. Fox,1 C. Rivetta,1 T. Mastorides,1 D. Van Winkle,1

T. Linnecar, 2 P. Baudrenghien,2 J. Tüchmantel2SLAC, CERN

• AB Dept., CERN, SLAC mutual interest.• Propose a concurrent plan of activities including the modeling,

analysis and evaluation of LHC RF station performance and beam stability and performance.

• CERN request - Adapt the PEP-II RF station identification configuration tool to the LHC LLRF task. Optimal situation, develop tool November 07 for use in RF station commissioning.

• Goals– Expand existing RF station models and include in the simulation

the low-mode coupled bunch beam dynamics.– Quantify the effect of LLRF imperfections and noise in the LLRF

implementation on the beam stability and longitudinal dilution.– Specify necessary performance for next-generation LLRF systems.

• Important for LLRF systems in future facilities and up-dates.


LLRF Task Resource Request

Phase I (FY2008)– 1 FTE Junior, 0.2 FTE Senior Salaries to be covered by LARP.– 0.5 FTE Senior Salary, covered by SLAC.– Travel: 3 visits x 2 weeks/visit to CERN.

RF Stations Configuration Tools - Commissioning Tasks– 0.25 FTE Senior Salary to be covered by LARP Commissioning.– Travel: 2-3 months at CERN, to be scheduled by CERN needs.

Phase II (FY2009) (duration 1 year post Phase I)– 0.75 FTE Junior, 0.4 FTE Senior Salaries to be covered by LARP.– 0.35 FTE Senior Salary, covered by SLAC.– Travel: 3 visits x 2 weeks/visit to CERN.– M&S: 15K$ in addition to SLAC R&D contribution for evaluation

modules and critical sampler components.


Control of E-Cloud Instabilities in the SPS

Feasibility study of feedback control of e-cloud instabilities in the SPS– Participate in SPS instability/e-cloud studies– Evaluate feasibility of feedback control (rather than grooves,coatings, scrubbing,..)– Propose a solution one year from now (if all goes well)

LARP Team: CERN:John Byrd (LBNL) Gianluigi ArduiniMiguel Furman (LBNL) Wolfgang HoefleJohn Fox (SLAC)Mauro Pivi (SLAC)

Block diagram of the prototype damping system tested at PSR.

Budget request: $75k


SLAC Component of SPD E-Cloud Support Request

Participation in E-Cloud studies at the SPSAdaptation of SLAC’s transient analysis codes to SPS and LHC data

structuresAnalysis of SPS and LHC beam dynamics studies, comparisons with Ecloud

models, participation in LHC transverse feedback system commissioningTechnical analysis

• Bunch-by-bunch dipole control (existing systems, possible enhancements or upgrades)

• Single bunch control (wideband, within bunch Vertical plane)ResourcesConsistent with J. Byrd request for Phase I

• 0.1 FTE Staff (J. Fox)• 0.2 FTE Graduate Student (J. Xu)

Based on the Phase I results, a more detailed Phase II proposal in 2009 would• develop the detailed requirements for a new wideband feedback system

architecture• key proof-of-principal technology R&D on GHz bandwidth (e.g. 2.5 GS/sec.)

processing

Summary of Accelerator Systems New Initiatives Parallel Session

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