# Presentation: 802490

## LARP Accelerator Physics

- Wolfram Fischer

- LARP Collaboration Meeting 9,** **Fermilab, 19 October 2007

## Accelerator Physics Tasks

- Electron cloud studies – M. Furman (LBNL)		 continuing
- Beam-beam wire compensation – W. Fischer (BNL)	 last year of task
- Beam-beam simulations – T. Sen (FNAL)			 changed scope (IR studies, formerly here, in new task)
- Electron lenses – V. Shiltsev (FNAL)			 new
- Crab cavities – R. Calaga (BNL)  				 new

- Total AP effort: ~ 2.5 FTEs

## Task: Electron cloud studies – M. Furman (1)

- Effects of e-cloud on the beam
- With code WARP/POSINST
- Quasi-static mode “QSM”, and with
- Lorentz-boosted frame method, fully self-consistent “FSC”
- Assessment of e-cloud build-up for PS2
- With build-up code POSINST (no effects on the beam)
- RHIC measurements
- Related e-cloud R&D (non LARP)

**Incoherent effects,**
**Computing intensive**

## Task: Electron cloud studies – M. Furman (2)

- Can now make parametric scansfor emittance growth from e-cloud,
- Work in progress

## Task: Electron cloud studies – M. Furman (3)

## Task: Electron cloud studies – M. Furman (4)

- Connections to other e-cloud work

## Task: Electron cloud studies – M. Furman (5)

- Connections to other e-cloud work

## Task: Beam-beam wire compensation – W. Fischer (1)

- Moveable wires installed in both RHIC rings, first use in 2007
- Measured effect of wires on Au beam
- At injection (10 GeV/nucleon Au)
- At store (100 GeV/nucleon Au)
- Benchmark simulation
- At CERN (U. Dorda)
- In Task Beam-beam simulations

## Task: Beam-beam wire compensation – W. Fischer (2)

- Movable wires in RHIC tunnel

## Task: Beam-beam wire compensation – W. Fischer (3)

- Orbit and tune response

## Task: Beam-beam wire compensation – W. Fischer (4)

## Task: Beam-beam wire compensation – W. Fischer (5)

**Experiments planned for 2008 (last year of task):**
- Will ask for 33 hr dedicated time again
- Would like to test effect on background with protons too (parasitic)
- Parameter scans (distance, strength) with protons
- Including head-on
- Different working points
- Attempt to compensate one long-range interaction

## Task: Beam-beam simulations – T. Sen (1)

- FNAL – H.J. Kim and T. Sen (BBSIM)
- Weak-strong simulations for SPS and RHIC wire experiments
- LBL – J. Qiang (Beambeam3D)
- Strong-strong simulations for RHIC and LHC emittance growth
- SLAC – A. Kabel (PlibB)
- Weak-strong simulations for RHIC wire experiments

**Visible progress in benchmarking experiments**

## Task: Beam-beam simulations – T. Sen (2)

- H.J. KimT. Sen

## Task: Beam-beam simulations – T. Sen (3)

- J. Qiang

## Task: Beam-beam simulations – T. Sen (4)

- A. Kabel

## Task: Beam-beam simulations – T. Sen (5)

**Work for 2008:**
- RHIC wire compensation
- LHC wire compensation, tolerances
- Simulations for different IR layouts
-       (1) Early separation   (2) Large crossing angle
- Rf noise and impact with beam-beam
- Crab cavity impact with beam-beam
- Additional physics in the codes: resistive wall wakefields, IBS, ....
- Diffusion solver; test of diffusion model
- Strong-strong effects, potential loss of Landau damping

## Task: Electron lenses – V. Shiltsev (1)

## Task: Electron lenses – V. Shiltsev (2)

## Task: Electron lenses – V. Shiltsev (3)

## Task: Electron lenses – V. Shiltsev (4)

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

## Task: Electron lenses – V. Shiltsev (5)

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

## Task: Crab cavities – R. Calaga (1)

- Crab cavities necessary for early separation scheme
- 800 MHz cavity under design (c < 0.6 mrad), could be built by AES/BNL with SBIR grant
- Study items
- Emittance growth from rf noise
- Collimation and machine protection

## Task: Crab cavities – R. Calaga (2)

## Task: Crab cavities – R. Calaga (3)

## Summary – LARP Accelerator Physics

- Moved lattice work into new task JIRS (A. Zlobin)
- Currently strong focus on beam-beam problems
- Wire compensation experiments in RHIC
- Beam-beam simulations efforts at FNAL, LBNL, SLAC
- Electron lens studies (Tevatron, RHIC, LHC)
- New proposal by Y. Cai
- Notable progress in beam-beam simulations
- Electron cloud studies
- E-cloud build-up in superconducting PS2 evaluated
- Simulations focus on incoherent e-cloud effects
- Find connections with SLAC-LBNL / SPS work on grooved chambers, and SPS feedback proposals (700 MHz)
- Crab cavity work started
- Design work by Ram Calaga
- Collaboration with BNL and AES for SBIR, others