# Presentation: 219023

## ILC Beam physics simulationNikolay Solyak(for ILC beam simulation group)

- ILC Beam physics simulationNikolay Solyak(for ILC beam simulation group)

**ILC main Linac lattice design : from ILC BCD-like to Realistic Realization**
**Single-bunch emittance preservation in ILC Main Linac using Dispersion Free Steering**
**Static Tuning: Local and Orthogonal Tuning Bumps**
**Dynamic Alignment: Ground Motion and Adaptive Alignment**
**New Codes : CHEF - DFS Implementation**

- Linac with misaligned quads and BPMs.

**“****Local” method**: *BPM readings (A**i**)* of only 3 (or more) Nneighboring quads are used to determine the necessary shifting of the central quad (***y**i*) 		(*V.Balakin, 1991*)

*conv *:  Speed of convergence of algorithm
*A**i*     :  BPM reading of the central quad and so on
*K**i*     :  Inverse of quad  focusing length
*L      *:  Distance between successive quads
*********E   ***:   Energy gain between successive quads
***E     ***:   Beam Energy at central quad

**Emittance preservation in ILC**

**Normalized vertical projected emittance vs. time in a  dispersion-free steered linac. AA (100 iterations, gain=0.3) is implemented after  every one hour**** ****of GM of model ‘C’. **

_**Electron Main Linac (9-8-9)**_

**RF Unit**

**Cryogenic Unit**

**SC String**

**Dynamic Tuning: Adaptive Alignment and Ground Motion**

- --After GM only
- -- After AA (1hr step)

- BPM res=0.2um

- BPM res=0 um

**Normalized emittance**

**Normalized emittance**

** ****Lattice defined by cryo segmentation (realistic cold & warm space drifts are used)**
** ****Linac curved along earth surface**
**Two version of segmentation**
** ****8-8-8 scheme (Nov.2006)**
** ****9-8-9 scheme (Dec. 2006)**
** ****Basic segmentations:  **

- undulator

- Linac      15-150 GeV

- Linac      150 -250 GeV

**ILC Main linac will accelerate e****-****/e****+**** from ~15 GeV****→ ****250 GeV**
** ****Upgradeable to 500 GeV**
**Emittance preservation is major issue (Luminosity frontier) **
**  **
***    ***
*** ******Vertical plane***** - more challenging:**
- Large aspect ratio (x:y) in both  spot size & emittance (400:1)
- ~2-3 orders of magnitude more difficult

**Luminosity**
**Scaling**

**Small normalized vertical emittance**

**ML Lattice Design**

_**Global Orthogonal Correctors**_
- Vector of particles final state (after DFS)
- Each corrector changes final state
- Minimum emittance growth when
- Perform SVD (orthogonal correctors)
- Columns of U are weights of correctors in orthogonal correctors
- Singular values of the matrix *K**svd* are quickly fall down. Only few first orthogonal correctors do the job.

**Orthogonal Correctors**

- 5  randomly chosen vertical correctors not working. Adjusted the  adjacent two correctors to guide the beam on to the design orbit

**BPM / Corrector Failure**

**Local Bumps**

**Faulty corrector not used in DFS**

**Corrected emittance (nm)**

**Orbit at the YCOR (m)**

**Exclude faulty correctors from the DFS and the results are fine**

- bump : Corrector # 3 & 36

- BPM index

- After DFS

- Bump #1

- Bump #2

- Locations of the dispersion bump is crucial to get the optimal result;
- No significant improvement in the emittance growth was observed after using three bumps;
- Wakefield bumps not help much after dispersion bumps

**Corrected emittance (nm)**

- BPM index

**Emittance dilution (nm)**

- Seed number

**Dispersion and Wakefield bumps can reduce emittance dilution significantly**

- zoom

- Nominal misalignments

- Orthogonal Correctors in TESLA-like (1Quad/4CM) lattice

- Dispersion only: No Wakefields, No Quad roll (X/Y coupling)

- Ground Motion models
- _(Technical noise incl.):_
- A – quiet (CERN-like)
- B – moderate (SLAC-like)
- C – Noisy (DESY-like)
- FNAL:  between A and B

- Emittance growth vs. time (~1month scale) in presence of ground motion (models A,B,C). Dynamic Adaptive Alignment Tuning keeps emittance under control.

- Emittance growth for two BPM resolutions (GM model B). Required resolution available after averaging in train

- Complete Static tuning Studies for realistic curved Lattice
- Complete Adaptive Alignment as Dynamic tuning method for RDR lattice
- Dynamic tuning:  Design FeedBack system
- Start-to-end simulation

- CHEF for LET simulations

**Future plans (EDR)**

- CHEF is C++ based Framework
- Successfully benchmarked against other codes in FY06/FY07
- Study of static tuning of the misaligned ILC Main Linac
- Preliminary Study of the steering performance with dynamic effects
- CHEF on FermiGrid computer

- Beam Jitter ~1um
- NUMI Ground motion