# Presentation: 123924

## 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**_

## 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

## 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

## Slide 5

## MIA Resource Request

**Manpower**
- Y. Yan: 1⁄2  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 LHCKarl 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 FeedbackAlan 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 DataWalter 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 CollidersYunhai 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-strong
- Gives 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

**Numeri****cal 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

## Optical Diffraction Radiation Pre-ProposalTanaji 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 LHCImpedance Control Architectures, Effects of technical implementation on accelerator performanceJ.D. Fox,1 C. Rivetta,1 T. Mastorides,1 D. Van Winkle,1T. Linnecar, 2 P. Baudrenghien,2 J. Tüchmantel2SLAC, 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 Arduini
- Miguel Furman (LBNL)		Wolfgang Hoefle
- John Fox (SLAC)
- Mauro Pivi (SLAC)

- Budget request: $75k

## SLAC Component of SPD E-Cloud Support Request

**Participation in E-Cloud studies at the SPS**
**Adaptation of SLAC’s transient analysis codes to SPS and LHC data structures**
**Analysis of SPS and LHC beam dynamics studies, comparisons with Ecloud models, participation in LHC transverse feedback system commissioning**
**Technical analysis**
- • Bunch-by-bunch dipole control (existing systems, possible enhancements or upgrades)
- • Single bunch control (wideband, within bunch Vertical plane)
**Resources**
- Consistent 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