collimation in the ilc bds carl beard astec daresbury laboratory people requirement recent successes...
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Collimation in the ILC BDS
Carl Beard
ASTeC Daresbury Laboratory
•People
•Requirement
•Recent Successes
•Future Aims
Carl Beard – Cockcroft SAC Meeting 23rd – 24th November 2006
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
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
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
Objectives
Carl Beard – Cockcroft SAC Meeting 23rd – 24th November 2006
Collimator Parameter and Beam Parameters
Beam Energy, GeV 250, 500
Material Cu, Ti, C
Penetration (mm) 2 to 10
e- Particles/bunch 2 x 1010
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
0.3 Xo of Ti alloy each side, central graphite part (blue).
0.6 Xo of Ti alloy leading taper (gold), graphite (blue), 1 mm thick layer of Ti alloy
Ti/C
2 mm, 10mm
250, 500 GeV e-
Carl Beard – Cockcroft SAC Meeting 23rd – 24th November 2006
Cu+Graphite spoiler
∆T [K]; 250 GeV e- ∆T [K]; 500 GeV e-
2 mm from top 465 K 860 K
10 mm from top 440 K 870 K
Difference -5% 1%
Fracture temp.
Melting temp.
Carbon zones Cu zones
500 GeV:σx = 79.5 µm, σy= 6.36 µm
250 GeV:
σx = 111 µm, σy= 9 µm
Carl Beard – Cockcroft SAC Meeting 23rd – 24th November 2006
Ti / Graphite Spoiler
∆Tmax = 575 K per a bunch of 2E10 e- at 500 GeV
σx = 79.5 µm, σy= 6.36 µm
270 K
405 K
540 K
2 mm deep from top
Ti alloy and graphite spoiler
400 K
Temperature data in the left only valid the Ti-alloy material. Top increase of temp. in the graphite ~400 K. Dash box: graphite region.
[L.Fernandez, ASTeC]
Carl Beard – Cockcroft SAC Meeting 23rd – 24th November 2006
Fluka Benchmark
0
100
200
300
400
500
600
700
0.5 1 1.5 2 2.5 3
Incident e-/um^2 (+/- 2 sigma)x10^7
Mel
ted
area
(um
^2)
Measurements courtesy of SLAC, Marc Ross et al.
Fluka Prediction of beam Damage (Evaporated material not considered
Measurements of Beam damage crater in cooper on the FFTB.
Carl Beard – Cockcroft SAC Meeting 23rd – 24th November 2006
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
Analytical Formula
Simulation Bench Tests (TDR)
Tests with Beam
Instant solution for only simple geometry
Real life measurements, slow turnaround time for measurements
Good indicator – poor resolution
Fast Results – Limited by Resolution/ confidence
Carl Beard – Cockcroft SAC Meeting 23rd – 24th November 2006
Simulation and Wire tests
Current TDR and TDT measurements are limited to 10 ps Pulse lengths.
TDR and TDT are being used to measure the Impedance of a vessel and its loss factor
Loss Parameter
-1.5
-1
-0.5
0
0.5
1
1.5
2
2.5
1E-09 1.2E-09 1.4E-09 1.6E-09 1.8E-09 2E-09 2.2E-09
Time (s)
Vo
lts
Launch Pulse
Transmitted Signal
Carl Beard – Cockcroft SAC Meeting 23rd – 24th November 2006
Achieving a 1 ps Pulse (In development)
Carl Beard – Cockcroft SAC Meeting 23rd – 24th November 2006
MAFIA Simulations
y = 0.5856x3 - 1E-14x2 + 0.4088x - 1E-13
-8
-6
-4
-2
0
2
4
6
8
-2.5 -2 -1.5 -1 -0.5 0 0.5 1 1.5 2 2.5
Beam Off set (mm)
Kic
k F
ac
tor
(V/p
C/m
m)
0.5mm Bunch
Poly. (0.5mm Bunch)
-15
-10
-5
0
5
10
15
0 0.001 0.002 0.003 0.004 0.005 0.006
Distance Z (mm)
Wakep
ote
nti
al (V
/pC
)
500 micron bunch
2mm offset
1.2mm offset
0.8mm offset
0.4mm offset
Carl Beard – Cockcroft SAC Meeting 23rd – 24th November 2006
Limitations / Advances
Limiting the simulations to short structures or only sufficient resolution for >>300 um bunch length.
A new technique is being applied to allow full structures to be simulated with substantially higher resolution
MAFIA/HFSS
GDFIDL / ECHO 2 &3D
Carl Beard – Cockcroft SAC Meeting 23rd – 24th November 2006
Beam Tests in ESA
Simple Shapes to allow benchmarking with Calculations/Code Geometric Wakefields Resistive Wall Wakefields Surface Roughness
=/2rad
r=3.8mm4
335mrad
r=1.4mm3
335mrad
r=1.4mm2
=335mrad
r=1.9mm1
Beam viewSide viewSlot
=/2rad
r=3.8mm4
335mrad
r=1.4mm3
335mrad
r=1.4mm2
=335mrad
r=1.9mm1
Beam viewSide viewSlot
h=38 mm
38
mm
h=38 mmh=38 mm
38
mm
38
mm
L=1000 mmL=1000 mmL=1000 mm
7mm
r=1/2 gate
=298mrad
=168mrad
r1 =3.8mm
r2 =1.4mm
4
1=/2 rad
2=168mrad
r1=3.8mm
r2=1.4mm
3
168mrad
r=1.4mm2
=/2rad
r=1.4mm1
Beam viewSide viewSlot
=298mrad
=168mrad
r1 =3.8mm
r2 =1.4mm
4
1=/2 rad
2=168mrad
r1=3.8mm
r2=1.4mm
3
168mrad
r=1.4mm2
=/2rad
r=1.4mm1
Beam viewSide viewSlot
h=38 mmh=38 mm
38 m
m38
mm
7 mm
208mm
28mm
159mm
Carl Beard – Cockcroft SAC Meeting 23rd – 24th November 2006
T-480 Experiment
Vertical mover
BPMBPM
2 doublets
~40m
BPM BPM
Two triplets
~16m
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 Experiment
Vertical mover
BPMBPM
2 doublets
~40m
BPM BPM
Two triplets
~16m
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
ESA z ~ 300m – ILC nominaly ~ 100m (Frank/Deepa design)
Magnet mover, y range = mm, precision = 1m
1500mm
Ebeam=28.5GeV
Carl Beard – Cockcroft SAC Meeting 23rd – 24th November 2006
Initial Comparison of Results
Just selecting one ref run (slot 0 ref) Just selecting one ref run (same slot ref)run q1 dq1 chisq/n run q1 dq1 chisq/n
599 -1.0117E-11 3.70281E-12 0.556841 599 -7.13552E-12 3.69547E-12 0.811254624 -1.16155E-13 3.39041E-12 0.861219 624 -6.36929E-13 3.4007E-12 1.153441
1491 1.26302E-11 1.10968E-12 73.30665 1491 1.26302E-11 1.10968E-12 73.30665w. mean 9.78258E-12 1.01429E-12 w. mean 9.96031E-12 1.01441E-12w. mean chisq -4.92422E-12 2.0283E-12 w. mean chisq-3.13033E-12 2.38158E-12
% %kf 1.74034675 0.180444912 10.36833 kf 1.771965811 0.180466779 10.18455
-0.876031954 0.360840007 -41.19028 kf (using chisq)-0.556893046 0.423690061 -76.08105
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
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