# Presentation: 803781

## LARP Accelerator Physics 

- 28 October 2008
- LARP Collaboration Meeting 11, FNAL
- Wolfram Fischer/BNL

*BNL - FNAL- LBNL - SLAC*

_**US LHC Accelerator Research Program**_

## Accelerator Physics Tasks in FY2009

- Electron cloud studies – M. Pivi (SLAC)
- Beam-beam – A. Valishev (FNAL)
- Crab cavities – R. Calaga (BNL)  [see presentation by R. Calaga]
- PS2 studies – U. Wienands (SLAC)

- LARP CM11 – 27-28 October 2008

- LARP Accelerator Physics -  W. Fischer

- Slide n°

- Total AP effort: ~ 3 FTEs

## Task: Electron cloud studies (M. Pivi, LBNL)

- FY2008 work concentrated on simulations (M. Furman, J.-L. Vay, LBNL)
- Benchmark WARP vs. HEADTAIL (emittance evolution)
- Benchmark POSINST(2D) vs. WARP(2D) and (3D) (build-up)
- E-cloud build-up simulation of SPS strip detector measurement
- SPS feedback simulations (started)

- LARP CM11 – 27-28 October 2008

- LARP Accelerator Physics -  W. Fischer

- Slide n°

## Task: Electron cloud studies (M. Pivi, LBNL)

- Goal for FY2009:
- 	propose a feedback system for the electron cloud driven vertical instability in the SPS(SPS performance with LHC design beams marginal due to electron cloud induced instability)
- People involved:
- 	J. Fox (SLAC)
- 	J. Byrd, M. Furman, J.-L. Vay, J. Thompson (LBNL)
- 	R. de Maria (BNL)
- 	G. Arduini, E. Benedetto, W. Höfle, G. Kotzian, E. Metral,G. Rumolo, B. Salvant, U. Wehrle (CERN)

- LARP CM11 – 27-28 October 2008

- LARP Accelerator Physics -  W. Fischer

- Slide n°

## Task: Electron cloud studies (M. Pivi, LBNL)

- LARP CM11 – 27-28 October 2008

- LARP Accelerator Physics -  W. Fischer

- Slide n°

- G. Arduini, ECLOUD04

- Instabilities in SPS:
-  horizontally	: coupled bunch
-  vertically	: single-bunch (e-cloud driven), freq. in GHz range

## Task: Electron cloud studies (M. Pivi, LBNL)

- LARP CM11 – 27-28 October 2008

- LARP Accelerator Physics -  W. Fischer

- Slide n°

- W. Höfle, WebEx meeting, 10/20/2008

## Task: Electron cloud studies (M. Pivi, LBNL)

- LARP CM11 – 27-28 October 2008

- LARP Accelerator Physics -  W. Fischer

- Slide n°

- W. Höfle, WebEx meeting, 10/20/2008

## Task: Electron cloud studies (M. Pivi, LBNL)

- LARP CM11 – 27-28 October 2008

- LARP Accelerator Physics -  W. Fischer

- Slide n°

- W. Höfle, WebEx meeting, 10/20/2008

## Task: Electron cloud studies (M. Pivi, LBNL)

- LARP CM11 – 27-28 October 2008

- LARP Accelerator Physics -  W. Fischer

- Slide n°

- Simulation J.L. Vay, WebEx meeting, 10/20/2008

## Task: Electron cloud studies (M. Pivi, LBNL)

- FY2009 work
- Characterize e-cloud instability better (SPS experiments)
- Simulate instability and damping
- Design feedback system
- Feedback system would have material costs >$1M(low level rf, amplifiers)
- May fit into APL (currently not in APL)

- LARP CM11 – 27-28 October 2008

- LARP Accelerator Physics -  W. Fischer

- Slide n°

## Task: Beam-beam (A. Valishev, FNAL)

- Had 3 beam-beam tasks in FY2008:
- Long-range beam-beam wire compensation 	(W. Fischer, N. Abreu, G. Robert-Demolaize, BNL)
- Simulations  	(T. Sen, H.J. Kim, FNAL; A. Kabel, SLAC, J. Qiang, LBNL)
- Electron lenses 	(V. Shiltsev, A. Valishev, V. Kamerdziev, FNAL)
- Now consolidated in a single task with emphasis on electron lenses, new task leader is A. Valishev, FNAL.

- LARP CM11 – 27-28 October 2008

- LARP Accelerator Physics -  W. Fischer

- Slide n°

## Task: Beam-beam (A. Valishev, FNAL)

- Three goals for FY2009:
- Conclude wire experiments at RHIC
- Experiments with Gaussian beam electron lens at the Tevatron
- Have simulation effort make a definitive statement on value of electron lens for head-on beam-beam compensation

- LARP CM11 – 27-28 October 2008

- LARP Accelerator Physics -  W. Fischer

- Slide n°

## Task: Beam-beam (A. Valishev) Wire experiments at RHIC (W. Fischer, N. Abreu, G. Robert-Demolaize)

- Goal: provide experimental data for long-range beam-beam effects as strong as in the LHC that can be used to benchmark beam-beam simulation codes
- No existing hadron machine has a long-range beam-beam effect as strong as LHC (~30 long-range interactions per IP)
- 2 wires designed, constructed and installed in RHIC to create strong long-range beam-beam effect
- Measurements done with Au and *d* beam so far(loss rate vs. distance, current, tune chromaticity)
- Proton measurements and corresponding simulations outstanding, task then finished

- LARP CM11 – 27-28 October 2008

- LARP Accelerator Physics -  W. Fischer

- Slide n°

## Task: Beam-beam (A. Valishev)Wire experiments at RHIC (W. Fischer, N. Abreu, G. Robert-Demolaize)

- LARP CM11 – 27-28 October 2008

- LARP Accelerator Physics -  W. Fischer

- Slide n°

- Vertically movable wires in RHIC tunnel.
- Max integrated strength 125 Am (80 Am needed for compensators in LHC, 2x/IP).

## Task: Beam-beam (A. Valishev)Wire experiments at RHIC (W. Fischer, N. Abreu, G. Robert-Demolaize)

- LARP CM11 – 27-28 October 2008

- LARP Accelerator Physics -  W. Fischer

- Slide n°

- Beam loss rate vs. wire position and current with *d* beam in Jan. 2008

- Had also planned to make scans with p and including head-on effect.But only short (3.5 wks) RHIC physics run with protons – no experimental time.
- Plan to perform proton scans in FY2009 – but will be a _short RHIC run again_.

## Task: Beam-beam (A. Valishev)Wire experiment simulations (T. Sen, H.J. Kim, A. Kabel, J. Qiang)

- LARP CM11 – 27-28 October 2008

- LARP Accelerator Physics -  W. Fischer

- Slide n°

- Simulated and measured beam loss rate as function of wire distance (RHIC *d* scan, 1/2008)

- Courtesy H.J. Kim, T. Sen, FNAL

- Onset of increased beamloss rate could be reproduced within 1for a number of the RHIC scans made.
- (independently also byU. Dorda, CERN, with
- Code BBTrack)
- Need to do this also for remaining proton measurements

## Task: Beam-beam (A. Valishev) Electron lenses (all)

- Goal: evaluate the LHC luminosity improvement with electron lenses for head-on beam-beam compensation, and other possible applications of electron lenses (e.g. ion collimation)
- Reducing tune footprints is not sufficient
- Work includes
- Experiments in the Tevatron with a Gaussian profile lens
- Numerical simulations
- Theoretical analysis
- Electron lenses could be included in the Phase II LHC IR upgrade.

- LARP CM11 – 27-28 October 2008

- LARP Accelerator Physics -  W. Fischer

- Slide n°

## Task: Beam-beam (A. Valishev) – Electron lenses (all)

- Need Gaussian gun for head-on compensation
- Current TEL lenses have flat profile with soft edges
- Built Gaussian profile gun for test (awaiting installation)

- LARP CM11 – 27-28 October 2008

- LARP Accelerator Physics -  W. Fischer

- Slide n°

- Courtesy V. Kamerdzhiev

- Planned Tevatron experiments:
-  Effect on of e-lens on tune spread
-  Determine tolerable noise levels  (position, current)

## Task: Beam-beam (A. Valishev) – Electron lenses (all)

- Numerical simulations, approach
- Show that beam-beam effect becomes unacceptable above certain beam-beam parameter 
- Turn on electron lenses to see improvement
- Not straight forward to determine acceptable beam-beam parameter 
- Figures of merit investigated:
- Short-term measures (tune footprint, tune and action diffusion, chaotic boarders) are all inconclusive when taken alone
- Dynamic aperture not a good measure for beam-beam problems
- Emittance growth probably too noisy signal in simulation
- Beam lifetime most promising but need a good model and sufficient CPU time

- LARP CM11 – 27-28 October 2008

- LARP Accelerator Physics -  W. Fischer

- Slide n°

## Task: Beam-beam (A. Valishev) – Electron lenses (all)

- LARP CM11 – 27-28 October 2008

- LARP Accelerator Physics -  W. Fischer

- Slide n°

- LHC simulation with LIFETRACKdifferent phase advances between IP and e-lens( =  with linear lattice and ideal e-lens is optimum)

- Lifetime simulations need benchmarking with existing machines (Tevatron, RHIC)
- Courtesy
- A. Valishev

## Task: Beam-beam (A. Valishev) – Electron lenses (all)

**Task: Beam-beam ****(A. Valishev)**** – ****Electron lenses ****(all)**

- LARP CM11 – 27-28 October 2008

- LARP Accelerator Physics -  W. Fischer

- Slide n°

- Related work: e-lens simulation study at RHIC – Y. Luo

- No BB

- BB

- Half comp.

- Full comp.

- Concluded that beam lifetimeis the best figure of merit fore-lens evaluation(this is different from magnet error evaluation)

## Task: Beam-beam (A. Valishev) – Electron lenses (all)

- In addition to LIFETRACK also plan to simulate beam lifetime with Sixtrack/MAD model (best single particle problem model available) to evaluate electron lenses
- After good experience at CERN and request for work from QMUL decided to use LHC@home project
- Uses BOINC technology (open-source software for volunteer and grid computing)
- About 180,000 volunteers from 177 countries offer screen saver time for this project
- Have excellent support at CERN (E. McIntosh, F. Schmidt)
- Server now at Queen Mary University, London,waiting for installation of a new Sixtrack executable needed for electron lens (hopefully this week)
- Plan to have mini-workshop on simulations after first results(about end of year)

- LARP CM11 – 27-28 October 2008

- LARP Accelerator Physics -  W. Fischer

- Slide n°

## Task: PS2 studies (U. Wienands, SLAC) 

- Goal: Support the design of the PS2 (replacement machine for the PS).
- Design of PS2 approved by CERN Council in June 2007.

- LARP CM11 – 27-28 October 2008

- LARP Accelerator Physics -  W. Fischer

- Slide n°

## Task: PS2 studies (U. Wienands, SLAC) 

- LARP CM11 – 27-28 October 2008

- LARP Accelerator Physics -  W. Fischer

- Slide n°

- U. Wienands

## Task: PS2 studies (U. Wienands, SLAC) 

- LARP CM#10 - 23 April 2008

- LARP Program Mgmt -  T. Markiewicz

- Slide n°  / 17

- U. Wienands

- Areas of collaboration

****** ****May be too large for LARP**

## Task: PS2 studies (U. Wienands, SLAC)

- FNAL interest, E. Prebys

- LARP CM11 – 27-28 October 2008

- LARP Accelerator Physics -  W. Fischer

- Slide n°

## Task: PS2 studies (U. Wienands, SLAC)

- LBNL interest (LBL)s

- LARP CM11 – 27-28 October 2008

- LARP Accelerator Physics -  W. Fischer

- Slide n°

- (main US effort currently at SNS,
- S. Danilov)

## Task: PS2 studies (U. Wienands, SLAC)

**Task: PS2 studies ****(U. Wienands, SLAC)**

- BNL interest (R. de Maria)

- LARP CM11 – 27-28 October 2008

- LARP Accelerator Physics -  W. Fischer

- Slide n°

- Luminescence monitor in RHIC

## Task: PS2 studies (U. Wienands, SLAC)

- Funding in FY2009 only $100k, some contributions from labs,only enough for work preparation, travel
- U. Wienands would like to see increase to $500k to $600k inFY2010 and FY2011 (plus some support from labs),would be about 4 FTEs
- Without lab support, effort would be about 2 FTEs

- LARP CM11 – 27-28 October 2008

- LARP Accelerator Physics -  W. Fischer

- Slide n°

## Summary – LARP Accelerator Physics 

- Currently 4 tasks, all are exploring larger activities later
- Electron cloud studies (M. Pivi, SLAC)specify SPS damping system for e-cloud driven instability[next step would be construction of damper]
- Beam-beam (A. Valishev, FNAL)finish RHIC wire experiments, Tevatron experiments with Gaussian TEL, evaluate electron lens benefits in simulations[next step would be electron lenses in RHIC, further simulations for LHC]
- Crab cavities (R. Calaga, BNL)already sizable activity, may grow larger [ see presentation by R. Calaga]
- PS2 studies (U. Wienands, SLAC)define scope for LARP in PS2 design[next step would be to do some of the proposed work]

- LARP CM11 – 27-28 October 2008

- LARP Accelerator Physics -  W. Fischer

- Slide n°