June 2 2007 Euro-TeV meeting 1

Accelerator Physics Summary

Paul Lebrun,

(Kyioshi Kubo, Daniel Schulte)

June 2 2007 2

Overview

• Organization: APY sessions + joints sessions– Topics are presented out of order with respect to the

agenda of the workshop• Starting with LET studies• Lessons learned from ML+APY, MET + APY

– (Apologies for possible repeats) – Essential part of our “service” function– Numerous Beam Studies are done within system areas.

• ending with key session: discussion on EDR

• Progress on:– Checks, depth, details on “classical” LET simulations:– Moving from static to dynamics – Integration…---> Interface, matching, X-talk between

feedback loops, S2E.– New problems

June 2 2007 3

Ring To Main Linac (RTML)

– No formal session on RTML, but an in depth talk by PT,

Andrea Latina and Kiyoshi Kubo on the state of the RTML

– Re-design during RDR process, prompted by:• Move of the Damping Rings (DR) -> long transfer line.

• LET performance not optimal though turn-around, spin rotator, bunch compressor.

• Bunch from DR length longer, momentum compaction in turn-around.

– Improvements • Optic design upstream of BC

• Matching to the site (vertical + horizontal bends &XY couplings) (on going effort..)

• Reducing the number of r.f. stations for bunch compressor..(cost saving)

June 2 2007 4

RTML

– Possible remaining concern(s):

• Time dependent stray fields in Return line : tolerance of ~2 nT, comparable to measurement at end of StationB, SLAC

• Space charge (> 10 km line @ 5 GeV) • Turn-around and spin rotator tuning, coupling &

Dispersion … Considering having complete, “4D”, emittance measurement system. (2D is baseline..)

• Overall performance of Bunch Compressor 1, with current cavity tilt tolerances.

• Moving to 2007 optics..

June 2 2007 5

LET Session, Main Linac

– Lattice Studies: Realistic (cryo system),

matching RTML, BDS • lattice files are version controlled, in a formal repository.

– Main Linac Undulator: Difficult problem, ongoing !

– Dynamical Studies: • Maintaining performance via 1-to-1, or better, Adaptive

alignment, post 1rst steering .. Now done on single desktop and on FermiGrid

• Progress on Dynamical Dispersion “Free” Steering on the Main Linac using CHEF

• 1st Steering, as the machine moves.• Ground Motion based on standard “ATL” model, or real

data, at Minos and/or Aurora mine tunnel

June 2 2007 6

Main Linac, Comments

– Cross-Checks: Running multiple codes, mainly

Lucretia & CHEF (FNAL), Merlin (DESY), PLACET (Cern),..

• Benchmarks (2006 saga completed… Must be ongoing when new code or physics introduced..)

– Static alignment of Main Linac satisfactory, albeit “bumps” (i.e., non-local corrections) are currently used.

June 2 2007 7

Short Lattice: 2 Dispersion and 1 Wake Bumps

1st dispersion bump

2nd dispersion bump

1st Wake bump

Pro

ject

ed

y-e

mitt

an

ce (

nm

)

After DFS

BPM #

1st dispersion bump : Corrector # 32nd dispersion bump : Corrector # 361st Wake bump : Corrector # 63

June 2 2007 8

Main Linac, To Do

Dynamical Studies: progress, still on going.• Model improvements..• Multiple feedback loops (e.g. 5Hz adaptive while re-

steering via DFS, downstream..)

• Undulator, steering ( static & Dynamics)• 1TeV: synchrotron radiation budget thermal

budge, while curving & steering.

June 2 2007 9

Beam Delivery System

– CERN: Offset & angle tuning at the IP

• Checks of previous Tesla studies. • Orbit feedback

– SLAC: Tuning studies, dynamic re-steering– Mature studies, advanced algorithms

June 2 2007 10

BDS Tuning

10 20 30 40 50

20

40

60

80

100

Tuning Iteration

Mea

n L

um

ino

sity

/ %

No

min

al

0 10 20 30 40 500

20

40

60

80

100

Tuning Iteration

% S

eed

s >

100

% N

om

inal

Lu

min

osi

ty

Disp, Waist, <x’y>, <xy>

tilt

dK

Two views – effectiveness of tuning sextupole mover knobs (dispersions, waists, couplings), then sextupole strengths and tilts

From PT’s talk, work done by Glenn White

June 2 2007 11

Code Development

• From LIAR to Lucretia– Relatively new code.. Benchmark phase, looks

good.– Customer base growing: code running at

Fermilab as well. – More physics capabilities for

• Beam Delivery System (BDS) being implemented.• Better Ground Motion interface• Field map tracking…

June 2 2007 12

Code Development

• PLACET:– Parallelism– Embedded Analysis tool (Octave) – …

• Guinea-Pig ++ (Beam-beam at IP)– C++, Parallelism, ..

• CHEF development @ Fermilab – r.f. cavity transport accuracy– Faster implementation of wake kicks– Parsers– ..

June 2 2007 13

Integration & “Start-to-End”

• Progress!! : – Beam Delivery System: BDSIM (S. Malton)

• G4 in, switch between fast, and (slower)…. • Ongoing..

– Start to End: ML -> IP• Tools : Merlin & Guinea-Pig

– Code + inputs, old recent.. – Mirror tracking..

– Recent Placet results (A. Latina) • Covering BC, ML and BDS

• It’s the process that matter, not the final answer!

June 2 2007 14

ML & LET joint session.

• Coupler Wakes :– Advanced computation of the wake potential

in Tesla style cavities, with the three couplers (Input, HOM) • New problem, need beam dynamic simulation!

• New Quadrupole Vibration data – Relatively flat transfer function– Yet, some amplification from stands -> quad– Scale matters: motion of ~ 500 nm observed,

improvements on stands foreseen..

June 2 2007 15

Metrology, ML, BDS & APY

• MonaLisa project– Nanometer Position measurement for Final

Focus (FF)• Position Measurement device for the FF quads, without

direct line of site through the IP (Also an MDI issue..)

• LICAS simulation status.– Looking forward to the upcoming system test

at DESY!

• Discussion on Jitter tolerance and mitigation between ML and BDS, impacting the BDS feedback systems. Need extra length.. Cost impact..

June 2 2007 16

Metrology, APY joint Discussion.

• Specs and understanding of procedures – Detail model of alignment errors, more than

one number! E.g., Systematic vs random

• Quad jitter through an entire Linac, at 2 K., under normal operating conditions (i..e, Helium and Nitrogen flowing at design rate)– Rely on simulation for now.. XFEL will bring

real data..

• More discussion and, small dedicated task force needed

June 2 2007 17

Focus on EDR

• Three ~1.5 hour sessions were dedicated to:– Review where we are in terms of organization,

scope etc.. – Planning, one with EDR management. – Yesterday late afternoon, we wrote the

following slides..

June 2 2007 18

Scope and Tasks of our group• Three main objectives

– Definitions or agreement on specifications– Preparation for high performance– Finding problems

• The first goal is quite demanding– Establish interfaces with lots of specializations– Perform studies to answer questions, define tolerances– Some specifications depend on beam-based correction

procedures

• Need to maintain core activity across subsystems– Not all issues can be solved locally– Some problems are common– Flexibility to find problems

• Draft tasks list written. – Specification & Models– Simulation studies.

June 2 2007 19

List of 10 Critical Issues

1. Define critical specifications for components .. e.g. for BPMs not only resolution but stability in time

2. Document specifications and rational/results3. Helical undulator integration4. RTML alignment and tuning5. Machine protection6. Dynamic imperfections and feedback

a) Locally and globallyb) e.g. can be a problem at noisy sites, feedback design and

performance7. Putting fires out:

.. e.g space charge, coupler wakefields, crab cavities8. Investigate alternatives

.. e.g. different main linac cavity designs9. Heat load (dark current)10. Think about unexpected problems

June 2 2007 20

Questions / Comments?

“Watch out, you can’t ignore what’s going on When your visions are drying outLike the oceans from the underworld…” -Alphaville

(last slide of PT’s talk on RTML)