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Collimation in the ILC BDS. Carl Beard ASTeC Daresbury Laboratory. People Requirement Recent Successes Future Aims. People. Task Leader – Nigel Watson (B’ham) Damage Studies L. Fernandez (ASTeC), A.Bungau (Manc) R. Barlow (Manc) G. Elwood (RAL), J. Greenhaulgh (RAL).

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collimation in the ilc bds

Collimation in the ILC BDS

Carl Beard

ASTeC Daresbury Laboratory

  • People
  • Requirement
  • Recent Successes
  • Future Aims
people
People
  • Task Leader – Nigel Watson (B’ham)
  • Damage Studies
    • L. Fernandez (ASTeC), A.Bungau (Manc) R. Barlow (Manc) G. Elwood (RAL), J. Greenhaulgh (RAL).
  • Wakefield Simulation and TDR
    • C. Beard (ASTeC), J. Smith (Lanc), R. Jones (Manc), R.Carter (Lanc), S Jamison (ASTeC), P Corlett (ASTeC)…
    • I. Zagorodnov (DESY),
    • M.Kärkkäinen, W.Müller, T.Weiland (TEMF)
  • Beam Tests (T-480 Experiment)
    • Frank Jackson…plus most of the above
    • SLAC ESA Team – Steven Malloy, Mike Woods…

Carl Beard – Cockcroft SAC Meeting 23rd – 24th November 2006

need for collimation
Need for Collimation
  • Reduce the background levels in the detector, by removing halo particles built up over the long linac.
  • Machine Protection, in the event of a beam miss-steer.

Collimators are introduced, as a result of this the change in impedance has detrimental effects to the beam quality.

The collimators have to be robust to withstand the full impact of several ILC Bunches.

Design / optimisation of spoiler jaws (geometry and materials) for wakefield and beam damage performance

Carl Beard – Cockcroft SAC Meeting 23rd – 24th November 2006

objectives
Objectives
  • Development of Advanced EM modelling methods
  • Benchmarking of wakefield calculations against experiments
    • SLAC ESA beam test / data analysis
    • RF bench tests (training/code comparisons)
  • Tracking simulations with best models of wakefields
  • Simulations of beam damage to spoilers
  • Material studies using beam test

Submitted 7 papers at EPAC, several EUROTeV reports/memos

Carl Beard – Cockcroft SAC Meeting 23rd – 24th November 2006

collimator parameter and beam parameters
Collimator Parameter and Beam Parameters

Copper

Fracture temperature ~200 °C (473 K)

Melting temperature 1085 °C (1357.77 K)

Carl Beard – Cockcroft SAC Meeting 23rd – 24th November 2006

collimator proposals
Collimator Proposals

250, 500 GeV e-

2 mm, 10mm

Ti/C

0.6 Xo of Ti alloy leading taper (gold), graphite (blue), 1 mm thick layer of Ti alloy

0.3 Xo of Ti alloy each side, central graphite part (blue).

Carl Beard – Cockcroft SAC Meeting 23rd – 24th November 2006

cu graphite spoiler
Cu+Graphite spoiler

Carbon zones

Cu zones

250 GeV:

σx = 111 µm, σy= 9 µm

500 GeV:

σx = 79.5 µm, σy= 6.36 µm

Fracture temp.

Melting temp.

Carl Beard – Cockcroft SAC Meeting 23rd – 24th November 2006

ti graphite spoiler
Ti / Graphite Spoiler

Temperature data in the left only valid the Ti-alloy material. Top increase of temp. in the graphite ~400 K. Dash box: graphite region.

540 K

405 K

400 K

270 K

∆Tmax = 575 K per a bunch of 2E10 e- at 500 GeV

σx = 79.5 µm, σy= 6.36 µm

2 mm deep from top

Ti alloy and graphite spoiler

[L.Fernandez, ASTeC]

Carl Beard – Cockcroft SAC Meeting 23rd – 24th November 2006

fluka benchmark
Fluka Benchmark

Fluka Prediction of beam Damage (Evaporated material not considered

Measurements of Beam damage crater in cooper on the FFTB.

Measurements courtesy of SLAC, Marc Ross et al.

Carl Beard – Cockcroft SAC Meeting 23rd – 24th November 2006

damage studies
Damage Studies
  • Beam tests are being planned to benchmark the Fluka/Geant Simulations
    • No electron beam is available with sufficient intensity
    • Or probability to hit the same point due to beam jitter.
  • Dynamic Simulations in ANSYS are being studied in support of the FLUKA/GEANT Simulations

Carl Beard – Cockcroft SAC Meeting 23rd – 24th November 2006

wakefield analysis
Wakefield Analysis

Instant solution for only simple geometry

Analytical Formula

Simulation

Bench Tests (TDR)

Fast Results – Limited by Resolution/ confidence

Good indicator – poor resolution

Tests with Beam

Real life measurements, slow turnaround time for measurements

Carl Beard – Cockcroft SAC Meeting 23rd – 24th November 2006

simulation and wire tests
Simulation and Wire tests

TDR and TDT are being used to measure the Impedance of a vessel and its loss factor

Current TDR and TDT measurements are limited to 10 ps Pulse lengths.

Carl Beard – Cockcroft SAC Meeting 23rd – 24th November 2006

achieving a 1 ps pulse in development
Achieving a 1 ps Pulse (In development)

Carl Beard – Cockcroft SAC Meeting 23rd – 24th November 2006

mafia simulations
MAFIA Simulations

Carl Beard – Cockcroft SAC Meeting 23rd – 24th November 2006

limitations advances
Limitations / Advances

Limiting the simulations to short structures or only sufficient resolution for >>300 um bunch length.

MAFIA/HFSS

A new technique is being applied to allow full structures to be simulated with substantially higher resolution

GDFIDL / ECHO 2 &3D

Carl Beard – Cockcroft SAC Meeting 23rd – 24th November 2006

beam tests in esa
Beam Tests in ESA
  • Simple Shapes to allow benchmarking with Calculations/Code
    • Geometric Wakefields
    • Resistive Wall Wakefields
    • Surface Roughness

Carl Beard – Cockcroft SAC Meeting 23rd – 24th November 2006

t 480 experiment

2 doublets

Two triplets

BPM

BPM

BPM

BPM

~40m

~16m

T-480 Experiment

Vertical mover

  • Wakefields measured in running machines: move beam towards fixed collimators
  • Problem
    • Beam movement  oscillations
    • Hard to separate wakefield effect
  • Solution
    • Beam fixed, move collimators around beam
    • Measure deflection from wakefields vs. beam-collimator separation
    • Many ideas for collimator design to test…

Carl Beard – Cockcroft SAC Meeting 23rd – 24th November 2006

t 480 experiment1

2 doublets

Two triplets

BPM

BPM

BPM

BPM

~40m

~16m

T-480 Experiment

Vertical mover

  • Wakefields measured in running machines: move beam towards fixed collimators
  • Problem
    • Beam movement  oscillations
    • Hard to separate wakefield effect
  • Solution
    • Beam fixed, move collimators around beam
    • Measure deflection from wakefields vs. beam-collimator separation
    • Many ideas for collimator design to test…

Carl Beard – Cockcroft SAC Meeting 23rd – 24th November 2006

wakefield box

1500mm

Wakefield Box

Ebeam=28.5GeV

ESA sz ~ 300mm – ILC nominal

sy ~ 100mm (Frank/Deepa design)

Magnet mover, y range = 1.4mm, precision = 1mm

Carl Beard – Cockcroft SAC Meeting 23rd – 24th November 2006

initial comparison of results
Initial Comparison of Results

Analytical: 0.562 V/pC/mm

MAFIA: 0.408 V/pC/mm

Beam Test 0.556 V/pC/mm

Carl Beard – Cockcroft SAC Meeting 23rd – 24th November 2006

future work
Future Work
  • Continue study into beam damage/materials
    • In the process of designing a 4th beam test
  • Collimators designed and built in EU, to be installed at SLAC ESA.
    • 3rd Physics run Mar/April 2007
  • Application of the Moving Mesh Technique
  • TDR Measurements with Optically generated 1 ps Pulse.
  • Combine information on geometry, material, construction, to find acceptable baseline design regarding all of
    • Wakefield optimisation
    • Collimation efficiency
    • Damage mitigation

Carl Beard – Cockcroft SAC Meeting 23rd – 24th November 2006

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