Introduction to ILC

1
Introduction to ILC

• Bob Kephart
• Fermilab

2
ILC History

• 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 Academys
  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 ILC Construction ???

Ingredients for a decision
3
Global Design Effort the Vision
Europe
Americas
Asia
2003? 7?
Joint Design, RD, 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/
4
International Linear Collider

• 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

5
ILC Schematic

• The ILC employs two 250 Gev linacs arranged to
  produce nearly head on ee- 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

6
ILC Operation

• 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 !

7
More ILC Parameters

• 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)

8
ILC systems

• 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
9
Talk Outline

• 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 RD
  is needed and where new people can engage.
• Subsequent speakers will expand on these RD
  opportunities
• System experts in the audience know much more
  than I do if I get it wrong hopefully they will
  chime in!

10
Electron Source

• What is it ?
• Produces a train of polarized electron bunches
• Nominal train is 2625 bunches of 2.01010
  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.

11
Electron Source
More on SC linacs later
8.3 M solenoid 3.16 Tesla !
12
Positron Source

• 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

13
Undulator-based Positron Source

• 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

14
Undulator Magnets

• 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

electrons
photons
electrons
target
other view
B field
15
Positron Target

• Large positron flux required
• Large diameter Ti target wheel rotated at 500
  rpm
• Limited lifetime due to radiation damage
• Remote handling needed hot cells located at
  surface
• Immersion in 67T field improves yield by 50

RD
Target and Optical Matching Device
Spinning Target Wheel w/ dc OMD
RD
SLAC
16
Positron Capture Cavity
Goal Power with 5 MW, 1 msec pulses to produce
15 MV/m gradient
RD
SLAC Prototype
Water Cooled L-Band Copper Cavity
17
Damping Ring

• 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.

18
Damping Ring

• 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 pulse-to-pulse
  variations in parameters such as the bunch charge

19
Damping Ring

• 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 re-accelerate only
  in the desired direction.
• Electrons (or positrons) becomes more and more
  parallel as transverse motion is damped

20
Damping Ring

• How does it work?
• When charged particles are accelerated they emit
  synchrotron radiation peaked (1/gamma) in the
  general direction of the particles motion

Photon
Re-acceleration By RF cavity
damped electron
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)
21
Damping Ring

• 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 ( 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 (lt3 ns
  rise/fall) to inject and remove individual
  bunches without disturbing neighboring bunches

RD
22
Other DR Challenges

• 2625 bunches, 2?1010 electrons or positrons per
  bunch, bunch length 9 mm
• Instabilities (classical, electron cloud, fast
  ion)
• Beam power gt 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

RD
RD
23
Damping Ring Schematic
Low emittance beams Instrumentation!
6.7 KM circumference
RD
650 MHZ SC RF system 200 M of 1.6 T wiggler
e- footprint is identical, but beamcirculates in
opposite direction.
24
RTML (Ring to Main Linac)

• 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
25
RTML

• 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
• Feed forward ??? Whats that ?

RD
26
RTML Feed-forward

• 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
27
RTML

• 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 !

28
Main Linac

• What is it ?
• The ILC is based on two Superconducting Radio
  Frequency (SRF) linacs of unprecedented scope
  ( total length23 km, 1680 Cryomodules, 14,560
  SRF cavities, all operating at an average
  gradient of 31.5 MV/m)

30 km
29
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

30
ML basic building block
ILC RF Unit 3 CM, klystron, modulator, LLRF
Baseline design now has 2 CM with 9 cavities, 1
CM with 8 cavities quad
31
Main Linac Parameters
Average beam power is 11 MW / beam ? wall plug to
beam efficiency is crucial ? Superconducting RF
32
Issues for ILC Main Linac

• Key issues for ILC Physics
• Machine Energy, Luminosity, Availability
• Technical Challenges
• Achieving high gradient in SRF cavities with a
  reproducible process (RD)
• Building Cryomodules with these cavities that
  meet ILC specification (RD)
• A reliable and efficient RF power source (RD)
• Industrialization of high volume components
• Cost Reduction ! (perhaps the most important RD)
• The Global Design Effort is addressing these
  challenges via a worldwide RD program

33
Cryomodule

• 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

34
Cryomodule

• 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

35
How do Cavities accelerate beam ?

• Cavities operate in the p mode
• Electric field direction alternates cell-to-cell

• Beam induced RF Power out

• RF Power in

36
Cryomodule

• 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 RD effort
37
ILC is based on TESLA CMs
Europe
38
ILC Cryomodule
2K Header and support
Vacuum Vessel
Radiation shields
Coupler
Cavity
2K He Vessel
Beam Axis
39
Superconducting Cavities

• 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 !

40
Cavities

• Why Niobium?
• Highest critical temperature (9.2K) and
  Critical field (Bc 1800 G) of all pure
  metals
• What limits cavity performance ? (Hasans talk)
• Surface defects ? quench
• Particulates ? field emission
• Ultimately, Peak Magnetic field on SC
• Cavity Shape RD increase Eacc for given Bpk

AES Tesla-shape
AES Re-entrant
Cavity Shapes under study
41
Evolution of Accelerating and Surface Magnetic
Fields
New Shapes era, LL and RE

• Single Cell Cavities

42
60mm-Aperture Re-Entrant Cavity, 58
MV/m!KEK/Cornell Collaboration

• World record !

• But still have to make 9 cells work

43
Cavity/CM process and Testing
Plan Develop in labs then transfer technology to
industry
44
SCRF Infrastructure

• 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)

45
Cavity Fabrication

• 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

AES
46
SCRF infrastructure

• Nb sheet Eddy Current Scanner

• Neat toys!

Finds defects in sheet Nb before fabricating
cavities

• defects few microns matter!

47
Main Linac

• Electron Beam Welder

48
Materials RD and QC

• 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

49
Quality Control Material RD
Nb Materials RD
Microscopy
RRR - measurements

• Purity, grain structure, and surface defects
  matter!

50
Basic SRF RD examples
Studies of flux penetration at grain boundaries
TIG weld Chamber _at_ MSU
GB2
GB2
H24 mT
H28 mT
GB2
Ar purification
H32 mT
Goal Cost reduction e.g no EB welding for end
groups
H40 mT
DC Magnetic flux penetrates when magnetic field
is parallel to plane of GB).
51
Cavity Tuning

• 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 gt 98
52
Cavity Surface Processing

• 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
• 8510 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? (RD)
• Your bathroom faucet was probably
  electro-polished

53
Electro-polish at DESY
54
U.S. Cavity Processing Test
Cavity Fabrication By Industry
Surface Processing _at_ Cornell
Surface Processing _at_ Jlab
Surface Processing _at_ ANL/FNAL
Vertical Testing _at_ Jlab
Vertical Testing _at_ Cornell
Vertical Testing _at_ FNAL
Exists
Cavity Dressing Horizontal Testing _at_ Fermilab
Developing
55
EP and Vertical Test _at_ TJNL

• TJNL has modified existing infrastructure for
  EP, HPR, and Vertical Test of 9-cell 1.3 GHz ILC
  cavities. ( gt 30/year )
• HPR high pressure rinse with ultra pure water

EP and Vert Test at TJNL
Quench at 42 MV/M but back down to 32 MV/M
56
EP Vertical Test Cornell
Vertical test
Vertical EP Infrastructure
HPR ( High Pressure Rinse)
ACCEL cavity EP Processed tested at Cornell
Limited by quench_at_ 30 MV/M

• New vertical EP RD infrastructure
• Modified HPR, and Vertical Test of 9-cell 1.3 GHz
  ILC cavities.

57
Surface Processing ANL/FNAL

• A new joint surface processing and test facility
• Clean rooms, BCP, and state of the art EP _at_ ANL
• New Chemistry and Clean Rooms, operational Oct 07
• New VTS system at FNAL being commissioned now

New Chemistry Rooms EP
New Clean Rooms
VTS
58
Cavity Dressing

• After successful vertical test
• Cavity welded inside He vessel
• Cavity opened to install main coupler
• Tuner added
• 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 RD Test Bed
• RD
• cavity tuners (slow), microphonics, Lorentz force
  detuning, high power RF processing3.9 GHz first,
  then 1.3 GHz cavities

Dressing
59
Cavity/Cryomodule Testing

• 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 (lt 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

60
Main Coupler

• 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 !

61
Coupler Schematic
62
Cavity Tuners

• 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

63
Cavity Tuners

• INFN
• Blade Tuner

• Saclay Type
• Lever Tuner

• Several mechanical solutions Cost ? Performance
  ?
• Marc will tell you more about these. (RD)

64
Cryomodule Assembly Facility
He Vessel Welding
Bare Cavity Test (VTS)
Tuners
Couplers
Test
Test
Dress Cavities
High Power Test ( HTS)
BPM
Cavity String Assembly In Clean Room
Magnet
Cryostat parts
Cryomodule Test
Module Assembly
65
Cryomodule Assembly
Assembly of a cavity string in a Class-100 clean
room at DESY
The inter-cavity connection is done in class-10
cleanroom
Cryomodule Assemby at DESY
66
Fermilab Cryomodule Assembly

• 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 RD Cryomodules (1/month)
• Use all this for tech transfer to industry

MP9 Clean Room
1st Cavity for HTS
String Assembly Fixture
ICB clean Fixtures being installed
67
TESLA Module Results
68
Cavity and Cryomodule Goals

• The GDE has established project wide RD 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 gt31.5 MV/M
• S2 goal Demonstrate a fully qualified ILC RF
  unit
• Coordinated International RD program
• FNAL is heavily engaged in this activity

69
Main Linac RF system
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
(9-8-9 Cavities per Cryomodule)
70
RF Pulse Shapes
71
Klystron

• 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)

72
Klystron Schematic
73
ILC Klystrons
Baseline 10 MW Multi-Beam Klystrons (MBKs) with
65 Efficiency Developed by Three Tube
Companies in Collaboration with DESY
74
Toshiba MBK Test Data
Nominal Power for 31.5 MV/m Operation

• Good but still performance and
• lifetime issues for all 3 (RD)

75
Modulators

• 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

76
ILC Baseline Modulator
IGCTs
77
Pulse Transformer Modulator Layout
78
Marx Generator Modulator (RD)
Charge in parallel, discharge in series 10 x 12
kv modules vernier
2 m
Fine Vernier
120 kV Output Cable
Buck Regulator
Coarse Vernier (31 Redundancy)
12 kV Cells (102 Redundancy)
79
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

80
ILC Cryogenic System

• 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 loads dominate
• Load per CM is small but it adds up!

Dynamic
Static
81
ILC Cryogenic System

• Heat load
• 37 KW at 2 K but efficiency 1/700
• 45 KW at 4.5 K efficiency 1/200
• ILC Cryo plant
• 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!

82
ILC Surface Presence
Undulators
RDR Plan 5 Cryo Plants /linac
LHC plant 18 KW at 4.5 K ILC plants are
similar
LHC coldbox
83
LHC Helium Compressor Station
Important issue is where to locate these on the
surface
84
LHC He Gas Storage Vessels
85
Beam Delivery System

• 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 1020 mm and by
  200400 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

86
BDS Challenges

• 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

87
Luminosity Beam Size

• frep nb tends to be low in a linear collider
• ILC achieves luminosity with small spot size and
  large bunch charge

88
Achieving High Luminosity

• Low emittance machine optics
• Contain emittance growth
• Squeeze the beam as small as possible

e-
e
5 nm
Interaction Point (IP)
89
ILC Availability Issues

• 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

90
Conventional Facilities

• 72.5 km tunnels 100-150 meters underground
• 13 major shafts gt 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

91
Main Linac Double Tunnel

• 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

92
Detector Concepts under development
LDC
GLD
SiD

• One IR region Two detectors push-pull
• Above ground assembly (similar to CMS)
• Detector RD in progress, world wide
  collaborations
• Few test beams in the world today Fermilab has
  one!

93
RDR Design Value Costs

• 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 _at_ 1,700
  hrs/yr)
• 1 ILC Unit 1 (2007)

• Reference design frozen Dec-06 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
• S Value 6.62 B ILC Units
• U.S. costs include GA, escalation, contingency,
  etc
• factor 2 or more higher

94
ILC Value by Area Systems

Main Cost Driver
Conventional Facilities Components
DRAFT PHG - Value Estimate - ORSAY - May 16, 2007
ILC - Global Design Effort
95
Schedule ?
2005 2006 2007 2008
2009 2010
Global Design Effort
Project
LHC Physics
Baseline configuration
Reference Design
Engineering Design
ILC RD Program
Expression of Interest to Host
International Mgmt
96
Main ILC RD activities at FNAL

• 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 RD
• Lots more detail in talks that follow

97
Summary

• The RDR is a complete self-consistent design for
  the ILC
• GDE RD 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 ? RD
• The RDR provides an excellent basis for the
  Engineering Design phase
• You dont have to be an accelerator physicist!
• Lots of places where lab users, university
  groups, students etc. can contribute!