accelerator physics summary
DESCRIPTION
Accelerator Physics Summary. Paul Lebrun, (Kyioshi Kubo, Daniel Schulte). 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 - PowerPoint PPT PresentationTRANSCRIPT
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)