Transcript Introduction to ILC Bob Kephart Fermilab FNAL ILC School

Americas
Introduction to ILC
Bob Kephart
Fermilab
July 25, 2007
FNAL ILC School
Slide 1
ILC History
Americas
1992-93
Start of TESLA Test Facility (DESY)
2001
TESLA TDR (proposed SC linacs)
2005
ITRP Technology decision (warm vs cold)
Formation GDE and Baseline Design
2006
EPP 2010 National Academy’s Report
endorses ILC (as the next Global HEP facility)
2007
ILC Reference Design & Cost released
2008
Start of Engineering Design
2010
Engineering Design Report
LHC Physics Results
~2012-20
July 25, 2007
Ingredients
for a
decision
ILC Construction ???
FNAL ILC School
Slide 2
Americas
Global Design Effort… the Vision
Europe
Americas
Asia
2003年 7月
Joint Design, R&D, Construction, Operations, Management
In this talk I will describe the ILC Reference Design
developed by the GDE
Link to RDR : http://www.linearcollider.org/cms/
July 25, 2007
FNAL ILC School
Slide 3
International Linear Collider
Americas
• Requirements set by the Physics:
• Parameters
• Electron-Positron Collider
• Ecm adjustable from 200 – 500 GeV
• Luminosity  ∫Ldt = 500 fb-1 in 4 years
• Energy stability and precision below 0.1%
• Electron polarization of at least 80%
• The machine must be upgradeable to 1 TeV
July 25, 2007
FNAL ILC School
Slide 4
Americas
ILC Schematic
• The ILC employs two 250 Gev linacs arranged to
produce nearly head on e+e- collisions
– Single IR with 14 mrad crossing angle
• Centralized injector
– Circular 6.7 km damping rings for electrons and positrons
– Undulator-based positron source
• Dual tunnel configuration for safety and availability
July 25, 2007
FNAL ILC School
Slide 5
ILC Operation
Americas
• The ILC is a single pass machine 
– the beam is not recirculated or reused
– instead is “dumped” after each crossing
• To make the required luminosity
– powerful electron & positron beams required (11 MW /beam)
– the beam size is made very small at the crossing point
•
To limit the overall power consumption of the
facility, one must use a acceleration technology with
very good “wall plug” to beam power efficiency.
– This has lead to the choice of Superconducting RF
– Nevertheless, the site power is still 230 MW !
July 25, 2007
FNAL ILC School
Slide 6
More ILC Parameters
Americas
• Overall parameters
–
–
–
–
–
–
2x1034 cm-2s-1 peak luminosity at 500 GeV center-of-mass
75% collider availability  500 fb-1 1st four years
9.0 mA average current during beam pulse
0.95 ms beam pulse and 1.5 ms rf pulse length
31.5 MV/M average gradient in Main Linacs
5 Hz operation
• Range of beam parameter for operability
–
–
–
–
–
2625 bunches
(1000 to 6000)
2x1010 per bunch (down to 1x1010)
11 MW beam power (down to 5 MW)
Bunch length: 200 to 500 mm at IP
IP spots sizes: sx ~ 620 nm (350 – 620) ; sy ~ 5.7 nm (3.5 – 9.0)
July 25, 2007
FNAL ILC School
Slide 7
ILC systems
Americas
• Main ILC systems:
– Electron and positron source, damping rings, RTML
– Main linacs (cryomodules, RF, cryogenics, etc)
– Beam delivery systems, Conventional Facilities
– skip: Controls, Instrumentation, Detectors
~30 km
July 25, 2007
FNAL ILC School
Slide 8
Talk Outline
Americas
• I will describe each of these systems and try
to explain what they do and how they work
• For each system I will point out areas where
R&D is needed and where new people can
engage.
• Subsequent speakers will expand on these
R&D opportunities
• System experts in the audience know much
more than I do… if I get it wrong hopefully
they will chime in!
July 25, 2007
FNAL ILC School
Slide 9
Electron Source
Americas
What is it ?
• Produces a train of polarized electron bunches
– Nominal train is 2625 bunches of 2.0×1010 electrons at 5 Hz
– Polarization greater than 80%.
How does it work ?
• A polarized laser beam illuminates a photocathode in
a “DC” gun ( ie HV = 140 KV is on all the time)
• Makes electron beam with longitudinal polarization
• Normal-conducting RF structures bunch the beam
and accelerate it to 76 MeV (bunch length 1ns  20 ps)
• Beam is accelerated to 5 GeV in a superconducting
linac for injection into the damping ring
– Superconducting solenoids rotate e- spin to vertical
– Separate SCRF structure provides energy compression.
July 25, 2007
FNAL ILC School
Slide 10
Electron Source
Americas
More on SC linac’s later
8.3 M solenoid
3.16 Tesla !
July 25, 2007
FNAL ILC School
Slide 11
Positron Source
Americas
What is it?
• Creates the positrons needed by the ILC
How does it work ?
• Electrons are accelerated part way down e- main linac
• They are diverted through a wiggler magnet
(undulator) that bends them back and forth causing
them to radiate photons (horizontal polarization)
• The photons hit a target and are converted to
electron-positron pairs
• The positrons are collected and injected into the
positron damping ring, cooled, then eventually
accelerated in the other e+ main ILC linac
July 25, 2007
FNAL ILC School
Slide 12
Undulator-based Positron Source
Americas
• Located at 150 GeV point in electron linac
–
–
–
–
~150 meter undulator followed by photon target
“Copper” RF structures capture positrons
Then accelerate in 5 GeV SCRF linac  e+ DR
Auxiliary “keep alive” source (10%)
• Schematic:
150 GeV
eDR
e- source
Photon
Collimators
e- Dump
Photon
Target Adiabatic
Matching
Device
July 25, 2007
IP
100 GeV
Helical
Undulator
In By-Pass
Line
Positron Linac
250 GeV
e- Dump
Photon
Dump
Auxiliary
e- Source
FNAL ILC School
e- Target
e+ pre-accelerator
~5GeV
Adiabatic
Matching
Device
e+
DR
Slide 13
Undulator Magnets
Americas
What is it ?
• A device to convert electron beam energy into
photons by creating a magnetic field of
alternating polarity.
How does it work?
• Electrons are bent back and forth causing them
to emit synchrotron radiation
• Also known as a wiggler magnet
photons
electrons
target
other
view
July 25, 2007
B field
FNAL ILC School
Slide 14
Positron Target
Americas
• Large positron flux required
– Large diameter Ti target wheel rotated at ~500 rpm
– Limited lifetime due to radiation damage
R&D
 Remote handling needed – hot cells located at surface
– Immersion in 6~7T field improves yield by ~50%
Target and Optical Matching Device
Spinning Target Wheel w/ dc OMD
R&D
SLAC
July 25, 2007
FNAL ILC School
Slide 15
Positron Capture Cavity
Americas
Goal: Power with 5 MW, 1 msec pulses
to produce 15 MV/m gradient
R&D
SLAC
Prototype
Water Cooled
L-Band
Copper Cavity
July 25, 2007
FNAL ILC School
Slide 16
Damping Ring
Americas
What is it ?
• The ILC damping rings include one electron
and one positron rings housed a single 6.7 km
long tunnel
• Both rings operate at 5 GeV
• One ring positioned directly above the other
Primary function
• Accepts electrons (and positrons) with large
transverse and longitudinal emittances and
produces low emittance beams needed for
luminosity production.
July 25, 2007
FNAL ILC School
Slide 17
Damping Ring
Americas
ALSO
• Damps incoming beam jitter to main linac
(transverse and longitudinal) to provide highly
stable downstream systems
• Delays bunches from the source to allow
feed-forward systems to compensate pulseto-pulse variations in parameters such as the
bunch charge
July 25, 2007
FNAL ILC School
Slide 18
Damping Ring
Americas
How does it work?
• As electrons circulate in the damping ring,
they lose energy by synchrotron radiation in
wiggler magnets
• Electrons are re-accelerated each time they
pass through RF cavities
• Synchrotron radiation decreases the motion
in any direction, while the cavities reaccelerate only in the desired direction.
• Electrons (or positrons) becomes more and
more parallel as transverse motion is damped
July 25, 2007
FNAL ILC School
Slide 19
Damping Ring
Americas
How does it work?
When charged particles are accelerated they emit
synchrotron radiation peaked (1/gamma) in the
general direction of the particles motion
Re-acceleration
By RF cavity
Desired direction of motion
Transverse components of electron motion are reduced
Vertical gets very small, horizontal limited by quantum
fluctuations in dipole bending magnets (ribbon beam)
July 25, 2007
FNAL ILC School
Slide 20
Damping Ring
Americas
One Challenge
• The ILC employs a long bunch train ~ 1 ms long
– ie 2625 bunches at 369 ns spacing
• If these electron bunches were stacked end-to-end in
a damping ring with this spacing it would have to
have a circumference of ~ 300 km !
The Solution
• Stack the bunches close together ( 8.6 ns spacing) in
a 6 km circumference ring and pull the damped
bunches out as needed every 369 ns
• Requires very fast magnetic kickers (3 ns rise/fall) to
inject and remove individual bunches without
R&D
disturbing neighboring bunches
July 25, 2007
FNAL ILC School
Slide 21
Other DR Challenges
Americas
• 2625 bunches, 21010 electrons or positrons per
bunch, bunch length= 9 mm
– Instabilities (classical, electron cloud, fast ion)
R&D
• Beam power > 200 kW
– Injection efficiency, dynamic aperture
• Must reduce emittance (V) by factor 106 in 200 ms
– 5 Hz rep rate  = 25 ms
– gx,y= 10-2 m-rad positron beams to (gx, gv)=(8  10-6, 2  10-8) m-rad
• Diagnostics
– Must develop instrumentation to accurately measure
these small beams
July 25, 2007
FNAL ILC School
R&D
Slide 22
Damping Ring Schematic
Americas
6.7 KM circumference
Low emittance beams
Instrumentation!
R&D
650 MHZ SC RF system
200 M of 1.6 T wiggler
-
e footprint is identical, but beam
circulates in opposite direction.
July 25, 2007
FNAL ILC School
Slide 23
RTML (Ring to Main Linac)
Americas
What does it do?
• Transports beam from the Damping Ring to the
upstream end of the main linac
• Bunch compressors reduce the long DR pulse by
factor of 30-45 to provide short bunches needed by
Main linac and at IP (9mm 0.3 mm)
515 GeV
July 25, 2007
FNAL ILC School
Slide 24
RTML
Americas
Description
• ~15 km long 5 GeV transport line (preserve emittance!)
• Spin rotators to orient the beam polarization to the
desired direction at the IP (usually longitudinal)
• Acceleration from 5 GeV to 13-15 GeV to limit the
increase in fractional energy spread associated with
bunch compression
• 180 degree turn around which enables feed-forward
beam stabilization
R&D
Feed forward ??? What’s that ?
July 25, 2007
FNAL ILC School
Slide 25
RTML Feed-forward
Americas
Feed-forward
• Just means you measure and incoming beam
parameter and use the measurements to make an
adjustment downstream in the machine
Measure
Feedback system
Correction device
e.g. adjustment of beam energy, position, angle, etc
July 25, 2007
FNAL ILC School
Slide 26
RTML
Americas
Challenges
• Control of emittance growth due to static
misalignments resulting in dispersion and
coupling (over ~15 km of beam line)
• Suppression of phase and amplitude jitter in
the bunch compressor RF which can lead to
timing errors at the IP
– RMS phase jitter of 0.24 degrees between the electron
and positron RF systems results in a 2% loss of
luminosity.
– 0.24 degree phase error at 1.3 GHz = 1/2 ps !
July 25, 2007
FNAL ILC School
Slide 27
Main Linac
Americas
What is it ?
• The ILC is based on two Superconducting Radio
Frequency (SRF) linacs of unprecedented scope
( total length=23 km, 1680 Cryomodules, 14,560 SRF cavities, all
operating at an average gradient of 31.5 MV/m)
~30 km
July 25, 2007
FNAL ILC School
Slide 28
Americas
Main Linac Features
• Each Main Linac roughly 11km in length
– 15 GeV  250 GeV
– Basic building block is the “RF unit”
• Each RF unit consists of :
– 3 cryomodules (26 cavities and one quad magnet)
– 10 MW multi-beam klystron (generates RF power)
– Modulator that supplies 120 kV HV pulse at 5 Hz
to Klystron (pulse width = 1.5 ms)
– RF distribution system delivers ~310kW per cavity
• Effective filling factor is ~67%
– Ie the fraction of the length that accelerates beam
July 25, 2007
FNAL ILC School
Slide 29
ML basic building block
Americas
ILC RF Unit: 3 CM, klystron, modulator, LLRF
Baseline design now has 2 CM with 9 cavities, 1 CM with 8 cavities + quad
July 25, 2007
FNAL ILC School
Slide 30
Americas
Main Linac Parameters
Parameter
Value
Parameter
Value
Initial Beam energy
15 GeV
Initial gx
8.4 mm
Final Beam energy
250 GeV
Final gx
9.4 mm
Particles per Bunch
2 x 1010
Initial gy
24 nm
Beam Current
9.0 mA
Final gy
34 nm
Bunch Spacing
369 ns
sz
0.3 mm
Bunch train length
969 ms
Initial sE/E
1.5%
Number of bunches
2625
Final sE/E
0.1%
Pulse repetition rate
5 Hz
Beam phase wrt RF crest
5o
Average beam power is 11 MW / beam  wall plug to beam
efficiency is crucial  Superconducting RF
July 25, 2007
FNAL ILC School
Slide 31
Issues for ILC Main Linac
Americas
• Key issues for ILC Physics
– Machine Energy, Luminosity, Availability
• Technical Challenges
– Achieving high gradient in SRF cavities with a reproducible
process (R&D)
– Building Cryomodules with these cavities that meet ILC
specification (R&D)
– A reliable and efficient RF power source (R&D)
– Industrialization of high volume components
– Cost Reduction ! (perhaps the most important R&D)
• The Global Design Effort is addressing these
challenges via a worldwide R&D program
July 25, 2007
FNAL ILC School
Slide 32
Cryomodule
Americas
What is it ?
• A cryomodule is a large cylindrical vacuum
vessel that maintains the superconducting
cavites at their operating temperature of 2 K
• Each cryomodule has either 8 cavities and a
quadrupole focusing magnet or 9 cavities
• RF energy from room temperature wave
guides is fed to each cavity via adjustable
coaxial couplers
• Cavity tuners adjust the cavity resonant
frequency to match that of the klystron
July 25, 2007
FNAL ILC School
Slide 33
Cryomodule
Americas
What does it do?
• RF energy is fed to the cavities at their resonant
frequency produces very high oscillating electric
fields ( 31 MV/m)
• The oscillations are arranged so that each cell of a
cavity produces a longitudinal electric field that
accelerates the electrons along the axis of the cavity
• The electrical losses are small such that essentially
all the RF energy is used to accelerate the beam
For steady state condition:
– RF Input Power = Cavity Voltage * Beam Current
July 25, 2007
FNAL ILC School
Slide 34
How do Cavities accelerate beam ?
Americas
• Cavities operate in the p mode
• Electric field direction alternates cell-to-cell
Beam induced RF
Power out
RF Power in
July 25, 2007
FNAL ILC School
Slide 35
Cryomodule
Americas
Cryomodules are complex
• Cavities operate in superfluid He
• Cavities are fabricated from pure Nb
• Cavity surfaces must be smooth and free of
particulates or contamination
Cryomodules are expensive
• ~ 20 km of main linac
• ~1.6 km of modules associated with sources
and bunch compressors
• Single most expensive component of the ILC
Extensive R&D effort
July 25, 2007
FNAL ILC School
Slide 36
ILC is based on TESLA CM’s
Europe
Americas
July 25, 2007
FNAL ILC School
Slide 37
ILC Cryomodule
Americas
2K Header
and support
Vacuum
Vessel
Radiation
shields
Coupler
Cavity
July 25, 2007
2K He
Vessel
FNAL ILC School
Beam
Axis
Slide 38
Superconducting Cavities
Americas
Remarkable devices!
• The quality factor Q0 of these cavities is ~ 1010
– Ratio of stored energy/ energy loss per cycle
– A church bell with Q0 ~ 1010 would ring for many months after
it was struck!
• Tiny RF energy loss is what allows SCRF cavities to
deliver most of the applied RF power to the beam
– vs a conventional linac where most RF power heats copper)
• However: the losses that due occur deposit heat
energy into the 2 K cavity operating environment
where it is very difficult to remove
– Negates part of the gain
– More on this later
• Think about it: 31 MV/M is 31 kV/mm !
July 25, 2007
FNAL ILC School
Slide 39
Cavities
Americas
• Why Niobium?
– Highest critical temperature (9.2K) and Critical field
(Bc =1800 G) of all pure metals
• What limits cavity performance ? (Hasan’s talk)
– Surface defects  quench
– Particulates  field emission
– Ultimately, Peak Magnetic field on SC
• Cavity Shape R&D : increase Eacc for given Bpk
AES Tesla-shape
AES Re-entrant
Cavity Shapes under study
July 25, 2007
FNAL ILC School
Slide 40
Evolution of Accelerating and
Surface Magnetic Fields
2500
60
Magnetic Field
Oersted
2000
55
Accelerating Field
50
45
1500
40
1000
35
New Shapes era,
LL and RE
500
0
1985
MV/m
Americas
1990
1995
2000
2005
30
25
20
2010
Year
Single Cell Cavities
July 25, 2007
FNAL ILC School
Slide 41
Americas
60mm-Aperture Re-Entrant Cavity, 58 MV/m!
KEK/Cornell Collaboration
World record !
But still have to make 9 cells work
July 25, 2007
FNAL ILC School
Slide 42
Cavity/CM process and Testing
Americas
Fail!
Cavity
Fabrication
Surface
Processing
Fail!
Horizontal
Testing
Vertical
Testing
Pass!
HPR or
reprocess
He Vessel,
couplers, tuner
Pass!
Cold String Assembly
Plan… Develop in labs then transfer technology to industry
July 25, 2007
FNAL ILC School
Slide 43
SCRF Infrastructure
Americas
• This process requires extensive infrastructure
• Bare cavities
–
–
–
–
Fabrication facilities (Electron beam welder, QC, etc)
Surface treatment facilities BCP & Electro-polish facilities (EP)
Ultra clean H20 & High Pressure Rinse systems
Vertical Test facilities ( Cryogenics + low power RF)
• Cavity Dressing Facilities ( cryostat, tuner, coupler)
– Class 10/100 clean room
– Horizontal Test System (cryogenics and pulsed RF power)
• String Assembly Facilities
– Large class 10/100 clean rooms, Large fixtures
• Cryo-module test facilities
– Cryogenics, pulsed RF power, LLRF, controls, shielding, etc.
– Beam tests  electron source (RF unit test facilities)
July 25, 2007
FNAL ILC School
Slide 44
Cavity Fabrication
Americas
• Sheet Nb is eddy current scanned (QA to
eliminate defects)
• Half cells are formed by deep drawing
sheets then annealed
• BCP cleaned prior to welding
• Half cells “dumb bells” via electron
beam welding
• End groups assemblies are fabricated via
EB welding: contain HOM and ports for
main coupler
• Entire 9 cell cavity is assembled by EBW
July 25, 2007
FNAL ILC School
AES
Slide 45
SCRF infrastructure
Americas
Nb sheet Eddy Current Scanner
Neat toys!
Finds “defects” in
sheet Nb before
fabricating
cavities
July 25, 2007
defects ~ few microns matter!
FNAL ILC School
Slide 46
Main Linac
Americas
Electron Beam Welder
July 25, 2007
FNAL ILC School
Slide 47
Materials R&D and QC
Americas
• Quality: Characterization of Nb sheet from vendors
– Surface properties: oxides, inclusions, and scratches via eddy
scanning of Nb sheet from vendors
– Measure material composition (RRR, chemical composition, etc)
– Measure Nb mechanical properties ( ie crystal structure)
• Surface studies
– Electropolish and BCP process studies (single cell programs)
– Surface contamination studies
– EM microscope, SIMS, atomic surface microscopy
• Nb crystal structure
– Small grain vs large grain vs single crystal cavities
• Weld studies ( e.g. TIG welding)
• Nationwide collaborative effort
July 25, 2007
FNAL ILC School
Slide 48
Nb Materials R&D
Americas
Quality Control – Material R&D
Microscopy
RRR measurements
Purity, grain structure, and surface defects matter!
July 25, 2007
FNAL ILC School
Slide 49
Basic SRF R&D: examples
Americas
TIG weld Chamber @ MSU
Studies of flux penetration
at grain boundaries
GB
#2
H=24 mT
H=28 mT
GB#2
Ar purification
Goal: Cost reduction: e.g no EB
welding for end groups
July 25, 2007
H=32 mT
H=40 mT
DC Magnetic flux penetrates when
magnetic field is parallel to plane of GB).
FNAL ILC School
Slide 50
Cavity Tuning
Americas
• Completed cavities are
mechanically tuned to correct
frequency and field flatness
• Automatic Tuning machine
– 16,000 cavities!
– FNAL is working with DESY & KEK
to develop new generation tuning
machines
– Bead pull & network analyzer
DESY Tuning machine
cavity pre-tuning example
initial measurement
after 1st pre tuning
Field flatness > 98%
July 25, 2007
FNAL ILC School
Slide 51
Cavity Surface Processing
Americas
What is it?
• During fabrication the Nb surface is highly deformed
and foreign material introduced
• Surface processing removes the damaged layer of Nb
and attempts to make smooth defect free interior
How does it work?
• The favored technique called electro polishing
• 85:10 mixture of Sulfuric, HF acid is introduced into
the cavity, a pure Aluminum electrode down the axis
• A DC current is applied that results in material
removal from the cavity interior…
• High spots are preferentially removed until the cavity
arrives at a mirror like finish
– The devil is in the details (R&D)
– Your bathroom faucet was probably electro-polished
July 25, 2007
FNAL ILC School
Slide 52
Electro-polish at DESY
Americas
July 25, 2007
FNAL ILC School
Slide 53
U.S. Cavity Processing & Test
Americas
Cavity Fabrication
By Industry
Surface
Processing
@ Cornell
Vertical Testing
@ Cornell
Surface
Processing
@ ANL/FNAL
Vertical Testing
@ FNAL
Cavity Dressing &
Horizontal Testing
@ Fermilab
July 25, 2007
FNAL ILC School
Surface
Processing
@ Jlab
Vertical Testing
@ Jlab
Exists
Developing
Slide 54
EP and Vertical Test @ TJNL
Americas
• TJNL has modified existing infrastructure for EP, HPR, and
Vertical Test of 9-cell 1.3 GHz ILC cavities. ( > 30/year )
•HPR = high pressure rinse with ultra pure water
A7 - Vertical Qualify Test Data
10
11
EP and Vert
Test at TJNL
10
10
10
Qo - First Qualify Test
Qo - 2nd Qualify Test
Qo- 3rd Qualify Test
Qo
9
Quench at ~ 42 MV/M
but back down to ~32 MV/M
10
8
0
10
20
30
40
Eacc (MV/m)
July 25, 2007
FNAL ILC School
Slide 55
Americas
EP & Vertical Test: Cornell
Vertical EP
Infrastructure
Vertical test
HPR
( High Pressure Rinse)
ACCEL cavity EP Processed
& tested at Cornell
•New vertical EP R&D infrastructure
Limited by
quench@ 30 MV/M
•Modified HPR, and Vertical Test of 9-cell 1.3
GHz ILC cavities.
July 25, 2007
FNAL ILC School
Slide 56
Surface Processing: ANL/FNAL
Americas
•
•
•
•
A new joint surface processing and test facility
Clean rooms, BCP, and state of the art EP @ ANL
New Chemistry and Clean Rooms, operational Oct 07
New VTS system at FNAL being commissioned now
New Clean Rooms
July 25, 2007
New Chemistry
Rooms & EP
FNAL ILC School
VTS
Slide 57
Americas
Cavity Dressing
• After successful vertical test:
– Cavity welded inside He vessel
– Cavity opened to install main coupler
– Tuner added
“Dressing”
• Test cavity again before its buried in a CM!
• Horizontal Test
– First test of the cavity with high pulsed RF power
– Also serves as high power R&D Test Bed
•
R&D:
– cavity tuners (slow), microphonics, Lorentz force
detuning, high power RF processing…3.9 GHz first,
then 1.3 GHz cavities
July 25, 2007
FNAL ILC School
Slide 58
Cavity/Cryomodule Testing
Americas
• “bare” cavities Tests
–
–
–
–
–
Vertical orientation in a “dewar” of LHe
Dewar is pumped to make it superfluid (2 K)
Tested with a low power CW source (< 500 W)
Resonate cavity to high electric gradient
Measure achievable gradient and Q
• Dressed Cavities Tests
– Coupler, tuner, and He vessel installed
– Test with pulsed RF power ~ 300 KW
– Tests tuner, coupler, etc before installation in CM
• Cryomodule test
– Test entire CM as it will be used in ILC
– Includes beam tests
• Sergei will describe these facilities
July 25, 2007
FNAL ILC School
Slide 59
Main Coupler
Americas
What is it?
• Transfers RF energy from a room temperature
RF wave guide into a cavity at 2 K
How does it work ?
• A transition is made from wave guide to a
coaxial input to an antenna inside the cavity
• Mechanically adjustable coupling to cavity
• Penetrates insulating vacuum, allows for
thermal contraction during CM cooldown
• Heat intercepts at 70 K and 4K
• Breakdown detectors, etc. Complicated !
July 25, 2007
FNAL ILC School
Slide 60
Coupler Schematic
Americas
Input
Power
July 25, 2007
FNAL ILC School
Slide 61
Cavity Tuners
Americas
What is it and how does it work ?
• A “flat” tuned cavity is like an accordion
• Pushing or pulling from the end changes the resonant
frequency ( remember that because of the high Q the
bandwidth is quite narrow)
– Qext = 3e6 so cavity Bandwidth is ~ 430 Hz
– 1 micron = ~300 Hz
• Slow tuners bring it in range (via motor)
• Fast tuners (piezoelectric) are pulsed to correct for
Lorentz force detuning during the RF pulse
• Different mechanical designs are under study
July 25, 2007
FNAL ILC School
Slide 62
Cavity Tuners
Americas
INFN
Blade Tuner
Saclay Type
Lever Tuner
Several mechanical solutions: Cost ? Performance ?
Marc will tell you more about these. (R&D)
July 25, 2007
FNAL ILC School
Slide 63
Cryomodule Assembly Facility
Americas
Bare Cavity
Test (VTS)
He Vessel
Welding
Couplers
Test
High Power
Test ( HTS)
July 25, 2007
Test
Dress
Cavities
Cavity String Assembly
In Clean Room
Cryomodule
Test
Tuners
Module Assembly
FNAL ILC School
BPM
Magnet
Cryostat
parts
Slide 64
Cryomodule Assembly
Americas
Assembly of a cavity string in a
Class-100 clean room at DESY
The inter-cavity connection is
done in class-10 cleanroom
July 25, 2007
Cryomodule Assemby at DESY
FNAL ILC School
Slide 65
Fermilab Cryomodule Assembly
Americas
• Where: MP9 and ICB buildings
– MP9: 2500 ft2 clean room, Class 10/100
– Cavity dressing and string assembly
– ICB: final cryomodule assembly
• Infrastructure:
– Assembly Fixtures
– Clean Vacuum, gas, water & Leak Check
• Goal: Produce R&D Cryomodules (~1/month)
• Use all this for tech transfer to industry
MP9 Clean Room
1st Cavity for HTS
String Assembly Fixture
ICB clean
Fixtures
installed
July 25, being
2007
FNAL ILC School
Slide 66
TESLA Module Results
Americas
July 25, 2007
FNAL ILC School
Slide 67
Cavity and Cryomodule Goals
Americas
• The GDE has established project wide R&D goals for
ILC cavities and cryomodule performance
• S0 goal: Establish a process & controls to reliably
achieve 35 MV/M in bare cavity tests (80% yield)
• S1 goal: Complete an ILC Cryomodule with all
cavities at working at an average accelerating
gradients >31.5 MV/M
• S2 goal: Demonstrate a fully qualified ILC RF unit
• Coordinated International R&D program
• FNAL is heavily engaged in this activity
July 25, 2007
FNAL ILC School
Slide 68
Main Linac RF system
Americas
Gradient = 31.5 MV/m
Bunch Charge = 2e10 e
Rep Rate = 5 Hz
Beam Current = 9.0 mA
Input Power = 284 kW
Fill Time = 596 ms
Train Length = 969 ms
July 25, 2007
(9-8-9
Cavities per Cryomodule)
FNAL ILC
School
Slide 69
RF Pulse Shapes
Americas
July 25, 2007
FNAL ILC School
Slide 70
Klystron
Americas
What is it?
• A RF amplifier that is used to produce the microwave
power that accelerates the beam
How does it work?
• A 1.5 ms HV pulse ( ~ 120 KV) is applied to heated
cathode producing an electron beam
• Low power RF applied to an upstream buncher cavity
modulates the beam into a bunches
• The bunched beam excites a stronger resonant RF
standing wave in a downstream catcher cavity
• The resultant field slows incoming electrons producing
RF power that can be extracted ( ~ 50-60% efficient)
• The “used” electrons produce heat (removed by water)
July 25, 2007
FNAL ILC School
Slide 71
Klystron Schematic
Americas
July 25, 2007
FNAL ILC School
Slide 72
ILC Klystrons
Americas
Baseline: 10 MW Multi-Beam Klystrons (MBKs) with ~ 65% Efficiency:
Developed by Three Tube Companies in Collaboration with DESY
Thales
July 25, 2007
CPI
FNAL ILC School
Toshiba
Slide 73
Toshiba MBK Test Data
Americas
Nominal Power
for 31.5 MV/m
Operation
Good… but still performance and
lifetime issues for all 3 (R&D)
July 25, 2007
FNAL ILC School
Slide 74
Modulators
Americas
What is it ?
• The device that turns wall plug power into the
HV pulses needed to drive klystrons
How does it work ?
• Several types: ILC baseline = “bouncer”
• A voltage supply charges a capacitor bank
• A HV switch discharges the bank through a
step up transformer
• Special circuits flatten the output pulse so it
does not droop as the capacitors discharge
July 25, 2007
FNAL ILC School
Slide 75
ILC Baseline
Americas
Modulator
IGCT’s
July 25, 2007
FNAL ILC School
Slide 76
Pulse Transformer Modulator Layout
Americas
July 25, 2007
FNAL ILC School
Slide 77
Marx Generator Modulator (R&D)
Americas
Charge in parallel, discharge in series
10 x 12 kv modules + vernier
Fine Vernier
120 kV Output Cable
Buck Regulator
Coarse
Vernier
(3+1 Redundancy)
12 kV Cells
(10+2 Redundancy)
July 25, 2007
FNAL ILC School
Slide 78
Americas
ILC RF Distribution Math
(for 33 MV/m Max Operation)
10 MW Klystron
33 MV/m * 9.0 mA * 1.038 m = 308 kW (Cavity Input Power)
× 26 Cavities
× 1/.93 (Distribution Losses)
× 1/.86 (LLRF Tuning Overhead)
═ 10.0 MW
July 25, 2007
FNAL ILC School
Slide 79
ILC Cryogenic System
Americas
What is it?
• The ILC SC cavities operate in superfluid He.
A large cryogenic system is required to
maintain them at 2 K
What does it do?
• A small amount of heat is generated at 2 K
and 4.5 K in each cryomodule
• 3 sources
– Small RF losses in the Nb cavities (AKA BCS losses)
– Beam induced RF energy absorbed at low temperature
– Heat load due radiation, conduction, imperfections
Dynamic
Static
• Dynamic loads dominate
Load per CM is small… but it adds up!
July 25, 2007
FNAL ILC School
Slide 80
ILC Cryogenic System
Americas
Heat load
• ~37 KW at 2 K
• ~45 KW at 4.5 K
ILC Cryo plant
but efficiency =1/700
efficiency = 1/200
– 10 large plants cool the SRF linacs
– 3 smaller plants mostly 4.5 K loads cool the
damping rings and collision region equipment
• These are big plants! (similar to LHC plants)
• They consume ~37 MW of wall plug power
• Estimated LHe inventory ~100 metric tons!
July 25, 2007
FNAL ILC School
Slide 81
ILC Surface Presence
Americas
Undulators
R
1.6 km
R
4.6 km
R
3.9 km
R
R
R
5.8 km
R
R
5.2 km
5 km
R
LHC plant =
18 KW at 4.5 K
R
5.2 km
RDR Plan
5
Cryo Plants
/linac
2.5 km
ILC plants are
similar
LHC coldbox
July 25, 2007
FNAL ILC School
Slide 82
LHC Helium Compressor Station
Americas
Important issue is where to
locate these on the surface
July 25, 2007
FNAL ILC School
Slide 83
LHC He Gas Storage Vessels
Americas
July 25, 2007
FNAL ILC School
Slide 84
Beam Delivery System
Americas
What is it ?
• Delivers the beam from the main linacs, focuses the
beam and maintains the beams in collision
What else does it do?
• Post-linac emittance and energy diagnostics
– Halo collimation and machine protection
– Tuning dump and fast extraction dump
• Final focus system
– IP beta functions of bx = 10~20 mm and by = 200~400 um
• Interaction region with 14 mrad crossing
– Crab cavity rotate bunches so they collide head on
– IR hall large enough for two detectors in a push-pull mode
– Surface buildings for detector assembly
July 25, 2007
FNAL ILC School
Slide 85
BDS Challenges
Americas
• Compact final quadrupoles
• Crab cavities with tight phase stability
• Tuning with tight jitter and alignment
tolerances  many feedback systems
• Beam collimation to limit backgrounds
without disturbing the beam
• Low loss extraction to main dumps of high
power (11 MW) disrupted beam with large
energy spread
July 25, 2007
FNAL ILC School
Slide 86
Luminosity & Beam Size
Americas
L
nb N 2 f rep
2p x  y
HD
• frep * nb tends to be low in a linear collider
L
ILC
SLC
LEP2
PEP-II
frep [Hz]
2x1034
5
2x1030
120
5x1031 10,000
1x1034 140,000
nb
3000
1
8
1700
N [1010] s x [mm] sy [mm]
2
4
30
6
0.5
1.5
240
155
0.005
0.5
4
4
• ILC achieves luminosity with small spot size
and large bunch charge
July 25, 2007
FNAL ILC School
Slide 87
Achieving High Luminosity
Americas
• Low emittance machine optics
• Contain emittance growth
• Squeeze the beam as small as possible
e-
e+
~ 5 nm
Interaction
Point (IP)
July 25, 2007
FNAL ILC School
Slide 88
ILC Availability Issues
Americas
Integrated Luminosity is what matters!
• ILC is ~10x larger than previous accelerators
• Aiming at an availability (uptime) of ~75%
• Predict very little integrated luminosity using
standard accelerator MTBFs and MTTRs
– Stringent requirements on component & system
availability
– Need improvement in MTBF ~10x on magnets, power
supplies, kickers, etc
– Drives choices such as redundant power and particle
sources and dual linac tunnels
• Potential for significant impact on project cost
MTBF = Mean Time Between Failure
July 25, 2007
FNAL ILC School
Slide 89
Conventional Facilities
Americas
• 72.5 km tunnels ~ 100-150 meters
underground
• 13 major shafts > 9 meter diameter
• 443 K cu. m. underground excavation:
caverns, alcoves, halls
• 92 surface “buildings”, 52.7 K sq. meters
= 567 K sq-ft total
July 25, 2007
FNAL ILC School
Slide 90
Main Linac Double Tunnel
Americas
• Cryomodules and LET in one 4.5 M tunnel
• Beam-on serviceable components in 2nd
– Three RF/cable penetrations every RF unit
– Safety crossovers every 500
July 25, 2007
FNAL ILC School
Slide 91
Detector Concepts under development
Americas
“SiD”
•
•
•
•
“LDC”
“GLD”
One IR region: Two detectors push-pull
Above ground assembly (similar to CMS)
Detector R&D in progress, world wide collaborations
Few test beams in the world today; Fermilab has one!
July 25, 2007
FNAL ILC School
Slide 92
RDR Design & “Value” Costs
Americas
• Reference design “frozen” Dec06 for cost estimate
• International “Value” System:
– Provides agreed upon
estimates of “value”
– Based on lowest reasonable
price for required quality
– Estimate of “explicit” labor
(man-hr)
– Snapshot in time
• Σ Value = 6.62 B ILC Units
• U.S. costs include G&A,
escalation, contingency, etc
– factor 2 or more higher
July 25, 2007
• Summary
• RDR “Value” Costs
• Total Value Cost (FY07)
• 4.80 B ILC Units Shared
• +
• 1.82 B Units Site Specific
• +
• 14.1 K person-years
• (“explicit” labor = 24.0 M person-hrs
@ 1,700 hrs/yr)
• 1 ILC Unit = $ 1 (2007)
FNAL ILC School
Slide 93
ILC Value – by Area Systems
Americas
• 4,500
Main
Cost
Driver
4,000
ILC Units - Millions
3,500
3,000
2,500
Conventional Facilities
2,000
Components
1,500
1,000
500
0
Main Linac
Damping Rings
DRAFT PHG - Value Estimate July 25, 2007
ORSAY - May 16, 2007
RTML
Positron Source
BDS
ILC - Global Design Effort
FNAL ILC School
Common
Exp Hall
Electron Source
Slide 94
Schedule ?
Americas
2005
2006
2007
2008
2009
2010
Global Design Effort
Baseline configuration
Reference Design
Project
LHC
Physics
Engineering Design
ILC R&D Program
Expression of Interest to Host
International Mgmt
July 25, 2007
FNAL ILC School
Slide 95
Main ILC R&D activities at FNAL
Americas
• Main Linac activities:
– Accelerator physics design in support of the RDR
– Demonstrate feasibility of all Main Linac technical
components (test facilities !)
– Engineering design of ML technical systems
– Estimates of the ML cost & cost reduction
– U.S. Industrialization of high volume ML components
• Civil and Site Development activities:
– Civil engineering of machine enclosures
– Study U.S. sites on or near the Fermilab site
– Estimate costs for conventional facilities
• Detector R&D
• Lots more detail in talks that follow
July 25, 2007
FNAL ILC School
Slide 96
Summary
Americas
• The RDR is a complete self-consistent design
for the ILC
– GDE R&D program to demonstrate technology
– Many issues: main linac cavities, power sources
and LLRF, damping ring instabilities and emittance
generation, BDS SC quadrupoles and crab cavities,
BDS tuning and operation, beam instrumentation
and hardware for high availability  R&D
• The RDR provides an excellent basis for the
Engineering Design phase
• You don’t have to be an accelerator physicist!
• Lots of places where lab users, university
groups, students etc. can contribute!
July 25, 2007
FNAL ILC School
Slide 97