Transcript CESR Test Facility Plans Mark Palmer Cornell Laboratory for Accelerator-Based Sciences and Education.

CESR Test Facility Plans
Mark Palmer
Cornell Laboratory for
Accelerator-Based Sciences and Education
Outline
• The International Linear Collider
– ILC Accelerator Research at Cornell
– Key Issues for the ILC Damping Rings
• CESR as a Vehicle for ILCDR Research - CesrTF
–
–
–
–
Concept and Goals
Ring Modifications
Parameters and Experimental Reach
The R&D Program
• Schedule
• Collaborators and Projects
– Local Participants
• Conclusion
October 6, 2006
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The International Linear Collider
Baseline Layout as of July 2006
• Key Milestones
– Costed Reference Design by the end of 2006
– Technical Design by the end of 2009
• An R&D Program To…
– Demonstrate the baseline design
– Optimize cost and perfomance
– Develop improvements to the baseline
See opening VLCW06 talk by B. Barish
http://vlcw06.triumf.ca/
• Ready in 2010 to propose construction
October 6, 2006
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ILC Accelerator R&D At Cornell
• Ring to Final Focus - Low Emittance Transport and BBA
• Helical Undulator for the Positron Source
• Superconducting RF
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–
–
–
Facilities: BCP, EP, HPR, Cavity Test
Re-entrant cavity development
Basic R&D on Niobium Cavities
650 MHz RF for Damping Rings
• Damping Rings
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–
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Simulation
Kickers
Wigglers
Instrumentation
CesrTF
October 6, 2006
Simulation Tools Based On BMAD
D. Sagan
http://www.lepp.cornell.edu/~dcs/bmad
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ILC@Cornell: RTML and Main Linac
• Low Emittance Transport
– Ring-to-Main Linac
(RTML)
– Bunch Compressor
– Spin Rotator
– Main Linac
Simulation Benchmarking
Emittance Growth in Main Linac
• J. Smith
BMAD/ILCv curve shows error bars
October 6, 2006
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Helical Undulator R&D
E166 Undulator
Preliminary polarization
• Built at LEPP
analysis consistent with
• Length = 1 m
expectations
• K = 0.17 (undulator param)
•  = 2.5 mm
ILC Undulator
• Aperture = 0.88 mm
• Length ~ 200 m
• 0.76 T
• K = 0.7
• 2300 A
•  = 10 mm
• 12 ms
• Aperture = 8 mm
A. Mikhailichenko
ILC Prototype
• Build 0.3 m unit
• Optimize field quality
• Evaluate effects on emittance
and polarization of e- beam
• Design, assemble and test
• Field measurement in vacuum
Collaboration with Daresbury
October 6, 2006
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SRF: Main Linac 9-cell Cavities
Assembly
Complete
October 6, 2006
LEPP Journal Club
Vertical
Test
7
Re-entrant Cavity Collaboration with
KEK
• Re-entrant Shape Single Cell Cavity Reached 47 MV/m in Nov 04
• 2nd Re-entrant Cavity (built at Cornell) Treated and Tested at KEK
Reached 50+ MV/m at KEK (Sept 05)
V. Shemelin
October 6, 2006
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The ILC Damping Rings
Beam energy
5 GeV
Circumference
6695 m
RF frequency
650 MHz
Harmonic number
14516
Injected (normalised) positron
emittance
0.01 m
OCS v6
TME Lattice
Extracted (normalised) emittance 8 μm × 20 nm
Extracted energy spread
<0.15%
Average current
400 mA
Maximum particles per bunch
2×1010
Bunch length (rms)
6 mm
Minimum bunch separation
3.08 ns
2 pm-rad geometric emittance
250 km main linac bunch train
is “folded” into the DRs
Circled items play a key role in our local R&D plans…
October 6, 2006
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ILCDR R&D Issues
• Some High and Very High Priority R&D Items
– Electron Cloud
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•
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Growth in bend magnets and wigglers
Suppression in bend magnets and wigglers
Instability thresholds and emittance growth in the positron damping ring
This issue has become more significant due to the decision to employ a single positron
damping ring
– Ion Effects
• Instability thresholds and emittance growth in the electron damping ring
– Ultra-low Emittance Operation
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Alignment and Survey
Beam-based Alignment
Optics Correction
Measurement and Tuning
– Fast (single bunch) high voltage kickers for injection/extraction
• >100 kV-m of stripline kick required
• <6 ns wide pulse into a 0.3 m long stripline so as not to perturb neighboring bunches in the
damping ring
– Development of 650 MHz SRF System
• We are in a position to make significant contributions to R&D in all of these areas at
Cornell
October 6, 2006
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Highlight One Issue
• Electron Cloud
– What is it?
• Primary electrons can be produced as photoelectrons from synchrotron
radiation, by gas ionization, and by lost beam particles striking the vacuum
chamber wall
• Secondary electrons are produced when free electrons are kicked by the
beam and strike the vacuum chamber walls
• Large amplification factors are possible and an electron cloud results
– Positively charged beams are particularly susceptible to emittance
growth and instabilities if the cloud density is high
– The cloud particles can be trapped by the fields of the magnets
around the ring
• Very strong fields in wigglers
– Cloud growth is very sensitive to the average currents and bunch
structure in the ring
October 6, 2006
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Moving to a Single Positron DR
M. Pivi
ILCDR06
Cloud density near (r=1mm) beam (m-3) before bunch passage, values are taken at a cloud
equilibrium density. Solenoids decrease the cloud density in DRIFT regions, where they are only
effective. Compare options LowQ and LowQ+train gaps. All cases wiggler aperture 46mm.
October 6, 2006
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Suppressing Electron Cloud in Wigglers
Submitted to PRSTAB
Design & test of impedance is under the
way, test in PEPII Dipole & CESR Wiggler
Strip-line type
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Wire type
10
average density, long train
central density, long train
average density, bunch train, -100V
central density, bunch train, -100V
average density, bunch train, 200V
central density, bunch train, 200V
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12
-3
 e (m )
10
14
10
10
10
stripline position
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10
9
0
20
40
60
80
100
120
Bunch ID
Suetsugu’s talk
Calculation of the impedance
( Cho, Lanfa)
Strip-line type
October 6, 2006
Wire type
LEPP Journal Club
L. Wang
ILCDR06
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CesrTF Overview
•
•
•
CESR-c HEP operations scheduled
to conclude on March 31, 2008
Design studies are presently
underway to modify CESR for ILC
Damping Ring R&D a CesrTF
4 Key Questions:
1.
2.
3.
4.
What can CESR offer as a damping
ring test facility?
How extensive are the required
modifications?
What is the resulting experimental
reach?
Can important R&D results be
provided in a timely fashion for the
ILC TDR and (hoped for) start of
construction?
October 6, 2006
LEPP Journal Club
South (CLEO) and North
Interaction Regions
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CesrTF Concept
• Reconfigure CESR as a damping ring test facility
– Move wigglers to zero dispersion regions for low emittance
operation
– Open up space for insertion devices and instrumentation
• Provide an R&D program that is complementary to work
going on elsewhere (eg, KEK-ATF)
• Provide a vehicle for
– R&D needed for TDR decisions (TDR complete at end of 2009)
– Operating and tuning experience with ultra-low emittance beams
– DR technical systems development
• Provide significant amounts of dedicated running time for
damping ring experiments
October 6, 2006
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Unique Features of R&D at CESR
CESR offers:
– The only operating wiggler-dominated storage ring in the world
– The CESR-c damping wigglers
• Technology choice for the ILC DR baseline design
– Physical aperture: Acceptance for the injected positron beam
– Field quality: Critical for providing sufficient dynamic aperture in the damping rings
– Flexible operation with positrons and electrons
– Flexible bunch spacings suitable for damping ring tests
• Presently operate with 14 ns spacing
• Can operate down to 4ns (or 2ns) spacings with suitable feedback system upgrades
– Flexible energy range from 1.5 to 5.5 GeV
• CESR-c wigglers and vacuum chamber specified for 1.5-2.5 GeV operation
• An ILC DR prototype wiggler and vacuum chamber could be run at 5 GeV
– Dedicated focus on damping ring R&D for significant running periods after the
end of CLEO-c data-taking
– A useful set of damping ring research opportunities…
• The ability to operate with positrons and with the CESR-c damping wigglers offers a
unique experimental reach
October 6, 2006
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CesrTF Goals
• Primary Goals
– Electron cloud measurements
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•
•
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e- cloud buildup in wigglers
e- cloud mitigation in wigglers
Instability thresholds
Validate the ILC DR wiggler and vacuum chamber design (critical for the
single 6 km positron ring option)
– Ultra-low emittance operations and beam dynamics
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•
•
•
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Study emittance diluting effect of the e- cloud on the e+ beam
Detailed comparisons between electrons and positrons
Also look at fast-ion instability issues for electrons
Study alignment issues and emittance tuning methods
Emittance measurement techniques
– ILC DR hardware development and testing
• ILCDR wiggler prototype, wiggler vacuum chamber, 650 MHz SRF ,
kickers, alignment & survey techniques, instrumentation, etc.
October 6, 2006
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CESR Modifications
• Move 6 wigglers from the CESR arcs to
the North IR (zero dispersion region)
North IR
– New cryogenic transfer line required
– Zero dispersion regions can be created
locally around the wigglers left in the
arcs
• Make South IR available for insertion
devices and instrumentation
• Instrumentation and feedback upgrades
CLEO
October 6, 2006
LEPP Journal Club
South IR
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The North IR
18 m region for wigglers and
instrumented vacuum chambers
North IR Modifications:
• Remove vertical separators and
install 6 wigglers
• Add cryogenics capability
• Instrumented vacuum chambers for
local electron cloud diagnostics
• Eventual test location for prototype
ILC damping ring wiggler and
vacuum chambers
• Move present streak camera
diagnostics area to South IR
October 6, 2006
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The South IR
South IR Modifications:
• Approx. 14 m of insertion device
space available after CLEO removal
• Cryogenics infrastructure available
• Beige volumes indicate insertion
regions
• Support for beam instrumentation
RF Cavities
for short bunch
length operation
shown here
Possible location for laserwire
installation. A 0.26 X0 Al
window is available 16.1 m to
the west. It is also possible to
place a 2nd window in the east.
October 6, 2006
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Instrumentation for Ultra-Low
Emittance Measurement
• Typical Beam Sizes
– Vertical: sy~10-12 mm
– Horizontal: sx ~ 80 mm (at a zero dispersion point)
• Have considered laserwire and X-ray profile monitors
– Fast X-ray imaging system (Alexander)
• Core diagnostic for CesrTF – high resolution and bunch-by-bunch capability
• Plan for integrating systems into CHESS lines
• First pinhole camera tests were successful! (see next slide)
– Laserwire
• CESR-c fast luminosity monitor offers window suitable for laserwire use
• Detector potentially could be used for fast segmented readout of Compton
photon distribution
October 6, 2006
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First bunch-by-bunch beam
size data in CHESS conditions a
Significant CHESS support
Signal (ADC Counts)
GaAs Detector for X-ray Imaging
s= 142 +/- 7 mm
Different symbols
represent different
bunches
Fast enough for
single bunch
resolution
October 6, 2006
LEPP Journal Club
Pinhole camera
setup at B1 hutch
Position (mm)
NEW: GaAs arrays from
Hamamatsu
• 1x512 linear array
• 25 mm pitch
• 1st sample has just arrived
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Luminosity Monitor Window
• Available for laserwire use
• Aluminum g Window
– Faces into South IR
– ~1 in thick (0.26 X0)
– 16.1 m from center of CesrTF
insertion region
– Looks at e+ beam
– Aperture (for 16.1 m):
• +/- 1.7 mrad vertical
• -7 to +2 mrad horizontal (negative
is to inside of ring)
• A similar window, but with
smaller horizontal aperture,
could potentially be added for
monitoring the electron beam
October 6, 2006
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CESR Modifications Summary
• How extensive are the modifications?
– Significant changes to the two IRs (however, certainly no more difficult than a
detector and IR magnet upgrade)
– Cryogenics transfer line must be run to the North IR
– 6 wigglers must be moved to the North IR
– Remove the electrostatic separators (single beam on-axis operation for CesrTF
and CHESS) – room for proposed CHESS undulators
– Feedback amplifiers and electronics will be upgraded to allow operation with 4
ns bunch spacing
• Could go to 2 ns with a more substantial upgrade
– Instrumentation must be upgraded
• Extend multi-bunch turn-by-turn BPM system to entire ring (presently single sector)
• High resolution emittance measurement techniques
• Conversion is relatively modest
– Approx. 7 months of down time required (with existing laboratory resources) to
remove CLEO and carry out the conversion
– Key preparation work carried out between now and April 2008
October 6, 2006
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Experimental Reach
Baseline Lattice
Parameter
E
Value
2.0 GeV
Nwiggler
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Bmax
2.1 T
ex
2.25 nm
Qx
14.59
Qy
9.63
Qz
0.098
sE/E
8.6 x 10-4
tx,y
47 ms
sz (with VRF=15MV)
6.8 mm
ac
6.4 x 10-3
tTouschek(Nb=2x1010 &
7 minutes
ey=5pm )
October 6, 2006
bx
by
Wigglers
hx
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Tune scans
• Tune scans used to identify suitable working points
Qx~14.59
October 6, 2006
Qy~9.63
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Lattice Evaluation
• Dynamic aperture
– 1 damping time
– Injected beam fully coupled
• ex = 1 mm
• ey = 500 nm
• Alignment sensitivity and
low emittance correction
algorithms
– Simulations based on
nominal CESR alignment
capabilities
October 6, 2006
Misalignment
Nominal Value
Quadrupole, Bend and Wiggler Offsets
150 mm
Sextupole Offsets
300 mm
Quadrupole, Bend, Wiggler and
Sextupole Rotations
100 mrad
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Vertical Emittance Sensitivities
(Selected Examples)
October 6, 2006
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Low Emittance Operations
• Have evaluated our
ability to correct for
ring errors with the
above lattice
Nominal Values
– Goal: ey~5-10 pm
at zero current
– Simulation results
indicate that we can
reasonably expect
to meet our targets
Correction Type
Average Value
95% Limit
Orbit Only
10.2 pm
21.4 pm
Orbit+Dispersion
3.9 pm
8.2 pm
October 6, 2006
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IBS Evaluation (2 GeV Lattice)
Vertical Emittance (pm)
Assumes coupling dominated
Bunch Length (mm)
Growth by 3.5x
Horizontal Emittance (nm)
October 6, 2006
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103 x Energy Spread
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Alternate Operating Point
• Want to study ECE impact at
ILC DR bunch currents
– 2.5 GeV lattice with sz ~ 9mm
– Zero current vertical emittance
chosen to be consistent with
above alignment simulations
– This emittance regime appears
consistent with studying the
impact of the ECE (and other
effects) on emittance dilution
• Presently working towards
more complete beam
dynamics simulations
October 6, 2006
LEPP Journal Club
Horizontal Emittance
Growth by 1.6x
Vertical Emittance
Bunch Length
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When Will R&D Results Become
Available?
• Immediate Plans
– Complete conceptual design work and validation
– Proposal submission in December
– Proposal will encompass our other areas of ILC accelerator research as well as
the test facility
• FY07
– Engineering design work
– Begin fabrication of items critical for 2008 down
• End of scheduled CESR-c/CLEO-c physics: March 31, 2008
– Install wigglers with new vacuum chambers immediately
• First dedicated CesrTF run in June 2008!
– Alternating operation with CHESS
– Estimate ~4 months/year of operations as a DR test facility
• This schedule is consistent with:
– Early results before TDR completion
– Significant program contributions before start of ILC construction
October 6, 2006
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The Next 1.5 Years
FY07
Apr
May
Jun
FY08
Jul
Aug
Sept
Oct
Nov
Dec
Jan
Feb
Mar
Ongoing Development Work for CesrTF
Retrofit 2 spare CESR-c 8-pole wigglers with new vacuum chambers
Preparatory Machine Studies: Electron Cloud, Ions, Low Emittance CESR-c Optics
General Preparation: Cryogenic Transfer Lines to North IR, Instrumentation,…
• Continue to develop the CesrTF Conversion Plan
• Prepare for wiggler vacuum chamber studies
– Collaboration: SLAC, LBNL
• Machine Studies
– Electron cloud and ion studies underway (see following slides)
– Plan to continue such work through the end of CESR-c
– Low emittance CESR-c (existing machine layout) optics have been designed:
ex ~ 6.5 nm
• General infrastructure preparation as can be supported by manpower
and funding resources
October 6, 2006
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CESR-c Wiggler Modifications
• Initial tests in CesrTF
• Remove Cu beam-pipe
• Replace with beam-pipe
with ECE suppression
and diagnostics hardware
• SLAC/LBNL Collaboration
October 6, 2006
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e+ Beam Size vs Bunch Current
0.25 mA
2 GeV vertical
bunch-by-bunch
beam size for 1x45
pattern, positrons
0.35 mA
Notice advancing
onset of beam size
blow up as a function
of bunch current
0.75 mA
1 mA
0.5 mA
October 6, 2006
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Theory and measurement of instability onset
Qualitative comparison: if the transverse eigen-frequency of the electron cloud
becomes comparable with the corresponding betatron frequency (xc), then the transverse
motion becomes unstable. Need to take into account the horizontal motion as well.
f p  MHz   0.5
0.4
b  10

a  m m   60
3 0.35
b 
0.3
0.11
b0.4
[mm] 0.25
0.35 mA
b
1/ 4
 2 2 
 1  2 b y 
c


0.2
0.15
0.1
0
10
20
30
40
50

See ILCDR06 Talk by L. Schachter –
https://wiki.lepp.cornell.edu/ilc/pub/Public/DampingRings/CornellWorkshopTalks/Schachter.Wake-Field_in_eCloud.ppt
October 6, 2006
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Proposed Transition Plan
FY08
Apr
D
o
w
n
May
CHESS
Jun
Cesr
TF
Install/Test 2 wigglers
w/modified Vacuum
Chambers
FY09
Jul
Aug
Sept
Down for North IR
Conversion
Oct
CHESS
Nov
Dec
CesrTF
Jan
Feb
Mar
Down for South IR
Conversion (4 months)
Install/Test full wiggler complement (including cryo
support) and vacuum diagnostics in North IR.
Instrumentation and Vacuum Diagnostics Upgrades
LiCAS Alignment/Survey Upgrades
• Initial focus on local ECE measurements
– Provides key TDR information
– Provides guidance for subsequent CesrTF investigations
• Start exploring low emittance operations
• 650 MHz SRF development getting underway
• ILC Wiggler Prototype development getting underway
October 6, 2006
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Survey and Alignment
Rapid Tunnel Reference Surveyor (RTRS) Concept
Proposal submitted for ILC DR alignment and survey studies using CesrTF
A. Reichold
wall markers
internal FSI
SM beam
external FSI
Tunnel Wall
LiCAS technology
for automated
stake-out process
Reconstructed
tunnel shapes
(relative coordinates)
collider component
October 6, 2006
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Prototype Operations Schedule
FY09
May
Jun
CHESS
Supporting
work can
occur here
(eg,
instrumentation)
Jul
Aug
CesrTF
Flexible
Operations
and Machine
Access
Running periods
approximately
50% CHESS/50% CesrTF
FY10
D
o
w
n
Sept
Oct
CHESS
Supporting
work can occur
here (eg,
instrumentation)
Nov
CesrTF
Flexible
Operations
and
Machine
Access
Running periods
approximately
50% CHESS/50% CesrTF
Dec
Jan
Feb
CHESS
Supporting
work can
occur here
(eg,
instrumentation)
Mar
CesrTF
Flexible
Operations
and Machine
Access
Apr
Down
Install
ILC
Prototype
Wiggler?
Running periods
approximately
50% CHESS/50% CesrTF
• Schedule along these lines presently under discussion
– Provides 4 dedicated running periods prior to TDR completion
• Envision a 5-year NSF operations proposal: April 1, 2008 – March
31, 2013
– Last 3 years would have a similar operating schedule to the FY09-FY10 version
October 6, 2006
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Organization
• CesrTF will be a collaborative endeavor
– LEPP will operate the machine
– LEPP will also contribute to the experimental program
– We expect to provide a significant fraction of the
machine time to collaborator experiments
– LEPP will provide accelerator physics and machine
support for collaborator experiments
October 6, 2006
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Collaborators
• Electron Cloud Simulation/Measurement/Suppression
– M. Pivi, L. Wang – SLAC; L. Schachter – Technion; K. Harkay – ANL; K.
Ohmi and J. Flannagan – KEK
• Wiggler vacuum chamber
– S. Marks, etal. – LBNL; M. Pivi, L. Wang – SLAC
• Alignment and Survey
– A. Reichold, D. Urner – LiCAS, Oxford
• Requirements and experimental plan
– J. Urakawa – KEK; A. Wolski – Cockroft Institute
• Low emittance instrumentation
– G. Blair – Adams Inst.; J. Alpert – CalTech; CHESS Colleagues
• Beam Dynamics Simulations
– A. Wolski – Cockroft Inst., M. Pivi, L. Wang – SLAC; P. Spentzouris, etal. –
FNAL; C. Celata – LBNL
October 6, 2006
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Acknowledgments
• CesrTF Studies
–
–
–
–
–
–
• CESR Machine Studies
–
–
–
–
–
–
–
M. Ehrlichman (Minn)
J. Shanks (REU)
R. Helms
J. Urban
D. Sagan
D. Rubin
October 6, 2006
LEPP Journal Club
G. Codner
E. Tanke
L. Schachter
M. Billing
M. Forster
D. Rice
J. Crittenden
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Conclusion
• CesrTF conceptual design work is ongoing
– The machine offers unique features for critical ILC
damping ring R&D
•
•
•
•
CESR-c wigglers
Operation with positrons and electrons
Flexible bunch configuration
Wide range in operating energy
– Simulations indicate that the emittance reach is suitable
for a range of damping ring beam dynamics studies
– The experimental schedule will allow timely results for
ILC damping ring R&D
• We would like to extend an open invitation to
anyone interested in collaborating on this project
October 6, 2006
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