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ILC-ECFA Workshop 2008Warsaw 9-12 June 2008
The European Laser ProjectThe European Laser Project XFEL and ILC
Carlo PaganiUniversity of Milano and INFN Milano-LASA
Index
Introduction: why accelerators as source for neutrons?– General principles of neutron production with accelerators
What is a high power accelerator and how does it work?– General layout– Superconductive choice
Applications of accelerator driven neutron sourcesApplications of accelerator driven neutron sources– Waste Transmutation (ADS)– Materials studies (SNS)
F i (IFMIF)– Fusion (IFMIF)
ILC-ECFA WorkshopWarsaw, 9 June 2008
Carlo Pagani2
Energy Frontier and Accelerator Tech.
Superconducting Magnets
ILC ∅ = 38”
Superconducting RF Cavities
LHC Dipole String
ACC 4 & ACC 5 in TTF
∅ = 38”ILC Cavity String
ILC-ECFA WorkshopWarsaw, 9 June 2008
Carlo Pagani3
ILC Cavity String
Energy Frontier and Accelerator Tech.
Superconducting Dipoles
ILC ∅ = 38”
Superconducting RF Cavities
LHC Dipole String
ACC 4 & ACC 5 in TTF
∅ 38”∅ = 38”
I C C i S i
ILC-ECFA WorkshopWarsaw, 9 June 2008
Carlo Pagani4
ILC Cavity String
No Circular e+e- Collider after LEP
Synchrotron Radiation:charged particle in a magnetic field: Energy loss dramatic for electrons
B [ ] [ ]kmr1106GeV 421 ⋅⋅⋅= − γSRU
USR = energy loss per turnγ = relativistic factorr = machine magnetic radius
γproton / γelectron ≈ 2000
Energy loss replaced by RF powercost scaling $ ∝ E 2
ILC-ECFA WorkshopWarsaw, 9 June 2008
Carlo Pagani5
cost scaling $ ∝ Ecm2
A Simple Exercise
Synchrotron Radiation (SR) becomes prohibitive for electrons in a circular machine above LEP energies:
[ ] 1421UUSR = energy loss per turn
RF system must replace this loss, and r scale as E2
[ ] [ ]kmr1106GeV 421 ⋅⋅⋅= − γSRU SR gy p
γ = relativistic factorr = machine radius
LEP @ 100 GeV/beam: 27 km around, 2 GeV/turn lostPossible scale to 250 GeV/beam i.e. Ecm = 500 GeV:– 170 km around
γ250GeV = 4.9 . 105
– 13 GeV/turn lostConsider also the luminosity– For a luminosity of ~ 1034/cm2/second, scaling from b-factories gives
~ 1 Ampere of beam current– 13 GeV/turn x 2 amperes = 26 GW RF power– Because of conversion efficiency, this collider would consume more power
than the state of California in summer: 45 GW
Circulating beam power = 500 GW
ILC-ECFA WorkshopWarsaw, 9 June 2008
Carlo Pagani6
than the state of California in summer: ~ 45 GWBoth size and power seem excessive
Origin of the Linear Collider Idea
M. Tigner, Nuovo Cimento 37 (1965) 1228
A Possible Apparatus for Electron-Clashing Experiments (*).
M. TignerM. TignerLaboratory of Nuclear Studies. Cornell University - Ithaca, N.Y.
“While the storage ring concept for providing clashing-beam experiments (1) is very elegant in concept it seems worth while at the present juncture to investigate otherworth-while at the present juncture to investigate other methods which, while less elegant and superficially more complex may prove more tractable.”
ILC-ECFA WorkshopWarsaw, 9 June 2008
Carlo Pagani7
Linear Collider Conceptual Scheme
Main LinacAccelerate beam
Final FocusDemagnify and collide beams
Bunch CompressorReduce σz to eliminate hourglass effect at IP
Accelerate beam to IP energy without spoiling DR emittance
Damping RingReduce transverse phase space (emittance) so smaller
IP i hi bl
Electron GunDeliver stable beam
transverse IP size achievablePositron TargetUse electrons to pair-produce positrons
ILC-ECFA WorkshopWarsaw, 9 June 2008
Carlo Pagani8
Deliver stable beam current
Fighting for Luminosity
2e
σσNL ∝ xσ repb fnL ×∝
NPnb = # of bunches per pulse
frep = pulse repetition rate
L = Luminosity
Ne = # of electron per bunch
yxσσyσ
p
yx
e
c.m.
b
σσN
EPL ×∝
Pb = beam power
Ec.m.= center of mass energy
σx,y = beam sizes at IP
IP = interaction point
Parameters to play withReduce beam emittance (εx
.εy ) for smaller beam size (σx.σy ) x y x y
Increase bunch population (Ne )Increase beam powerI b t l ffi i f t
( )repbb fnNP ××∝ e
ILC-ECFA WorkshopWarsaw, 9 June 2008
Carlo Pagani9
Increase beam to-plug power efficiency for cost
Competing technologies for the ILC
Evolution from: SLAC & SLC
1.3 GHz - Cold
Evolution from: CEBAF & LEPII
11.4 GHz - Warm
+ TRISTAN, HERA, etc.
ILC-ECFA WorkshopWarsaw, 9 June 2008
Carlo Pagani10
30 GHz-Warm12 GHz - Warm
Beam Sizes: Pictorial View
© M. Tignerg
ILC-ECFA WorkshopWarsaw, 9 June 2008
Carlo Pagani11
LC Organisation up to August 2004
ILC-ECFA WorkshopWarsaw, 9 June 2008
Carlo Pagani12
Technology Choice:NLC/JLC or TESLA
The International Linear Collider Steering Committee (ILCSC) selected the twelve members of the International Technology Recommendation Panel (ITRP) at the end of 2003:Recommendation Panel (ITRP) at the end of 2003:
Asia:G.S. Lee
Europe:J-E Augustin
North America:J. Bagger
A. MasaikeK. OideH. Sugawara
gG. BellettiniG. KalmusV. Soergel
ggB. Barish (Chair)P. GrannisN. Holtkampg g p
First meeting end of January 2004 at RAL
Mission: one technology by end 2004
Result: recommendation on 19 August 2004
ILC-ECFA WorkshopWarsaw, 9 June 2008
Carlo Pagani13
g
From the ILC Birthday
ILC-ECFA WorkshopWarsaw, 9 June 2008
Carlo Pagani14
From the ILC Birthday
ILC-ECFA WorkshopWarsaw, 9 June 2008
Carlo Pagani15
The ILC technology choiceStanding wave: Vph = 0 and Vg = 0
TESLA: f = 1.3 GHz
Remembering that the power dissipated on the cavity walls to sustain a field is:
∫= sdiss dSHRP 2
2standing wave case
π mode
∫S
diss 2a pulsed operation is required to reduce the time in which the maximum allowable field is produced to accelerate the particlesThe power is deposited at the operating produced to accelerate the particles
1 0E 05
1.0E-04
1.0E-03
and
Cu
Rs
The power is deposited at the operating temperature of 2 K
We need to guarantee and preserve the 2 K environment
1.0E-07
1.0E-06
1.0E-05
Rat
io b
etw
een
Nb
2 K4.2 K
environmentCavity is sensitive to pressure variations, only viable environment is sub-atmospheric vapor saturated He II bath
1.0E-080 500 1000 1500 2000 2500 3000
f [MHz]
RWe need a thermal “machine” that performs work at room temperature to extract the heat deposited at cold
We can’t beat Carnot efficiency!
ILC-ECFA WorkshopWarsaw, 9 June 2008
Carlo Pagani16
We can t beat Carnot efficiency!Cryogenics and cryomodules
How is spent the cold advantage?
The gain in RF power dissipation with respect to a normal-conducting structure is spent in different ways
TTPaying the price of supplying coolant at 2K
– This include ideal Carnot cycle efficiencyMechanical efficiency of compressors and refrigeration items
c
ch
TTT
QW−
≥
– Mechanical efficiency of compressors and refrigeration items– Cryo-losses for supplying and transport of cryogenics coolants– Static losses to maintain the linac cold
Increasing of the duty cycle (percentage of RF field on)– Longer beam pulses, larger bunch separation, but also– Larger and more challenging Damping Rings
Increasing the beam power (for the same plug power)
ILC-ECFA WorkshopWarsaw, 9 June 2008
Carlo Pagani17
– Good for Luminosity
Linear Colliders are pulsed
LCs are pulsed machines to improve efficiency. As a result: • duty factors are small• pulse peak powers can be very largep p p y g
RF Pulse<10 200 ms
<1 µs-1ms
RF Pulse<10-200 ms
Bunch Train1-300 nsec
100 m - 300 km…………………....
……
gradient
Beam Loading
gradientwith further input
without inputaccelerating field pulse:
ILC-ECFA WorkshopWarsaw, 9 June 2008
Carlo Pagani18
filling loading
The TESLA Collaboration Mission
Develop SRF for the future TeV Linear ColliderBasic goals
• Increase gradient by a factor of 5 (Physical limit for Nb at ~ 50 MV/m)• Increase gradient by a factor of 5 (Physical limit for Nb at ~ 50 MV/m)• Reduce cost per MV by a factor 20 (New cryomodule concept and Industrialization)• Make possible pulsed operation (Combine SRF and mechanical engineering)
Major advantages vs NC Technologyj g gy• Higher conversion efficiency: more beam power for less plug power consumption• Lower RF frequency: relaxed tolerances and smaller emittance dilution
as in 1992
ILC-ECFA WorkshopWarsaw, 9 June 2008
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Björn Wiik
TESLA Collaboration MilestonesInfrastructure
@ DESY in Hall 3February 1992 – 1 TESLA Collaboration Board Meeting @ DESYMarch 1993 - “A Proposal to Construct and Test P t t S d ti RF St t f
TTF I
Prototype Superconducting RF Structures for Linear Colliders”1995 – 25 MV/m in multi-cell cavityMay 1996 – First beam at TTF
TESLA Collider
May 1996 First beam at TTFMarch 2001 – First SASE-FEL Saturation at TTFMarch 2001 – TESLA Technical Design Report
TESLA X-Ray FELFebruary 2003 –TESLA X-FEL proposed as an European Facility,50% funding from Germany2004 – FLASH (TTF II) Commissioning start
FLASH
2004 FLASH (TTF II) Commissioning startApril 2004 - 35 MV/m with beamAugust 2004 - TESLA Technology chosen for ILC
ILC-ECFA WorkshopWarsaw, 9 June 2008
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June 2007 – Formal start of the XFEL Project
Luminosity & Beam Size
Dyx
repb HfNn
Lσπσ2
2
=
frep * nb tends to be low in a linear collider
y
L frep [Hz] nb N [1010] σx [μm] σy [μm]rep [ ] b [ ] x [μ ] y [μ ]ILC 2x1034 5 3000 2 0.5 0.005SLC 2x1030 120 1 4 1.5 0.5LEP2 5x1031 10,000 8 30 240 4
The beam-beam tune shift limit is much looser in a linear collider than a
,PEP-II 1x1034 140,000 1700 6 155 4
The beam beam tune shift limit is much looser in a linear collider than a storage rings achieve luminosity with spot size and bunch charge– Small spots mean small emittances and small betas:
sqrt (β )
ILC-ECFA WorkshopWarsaw, 9 June 2008
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– σx = sqrt (βx εx)
Luminosity & Beam Size
Dyx
repb HfNn
Lσπσ2
2
=
frep. nb tends to be low in a linear collider
y
L frep [Hz] nb N [1010] σx [μm] σy [μm]
ILC 2x10 34 5 3000 2 0.5 0.005SLC 2x10 30 120 1 4 1.5 0.5LEP-II 5x10 31 10,000 8 30 240 4LEP-II 5x10 10,000 8 30 240 4PEP-II 1x10 34 140,000 1700 6 155 4
The beam-beam tune shift limit is much looser in a linear collider than a storage rings achieve luminosity with spot size and bunch charge– Small spots mean small emittances and small betas:
σ = sqrt (β ε )
ILC-ECFA WorkshopWarsaw, 9 June 2008
Carlo Pagani22
σx = sqrt (βx εx)
Luminosity & Beam Size
Dyx
repb HfNn
Lσπσ2
2
=y
L frep [Hz] nb N [1010] σx [μm] σy [μm] Pb
ILC 2x10 34 5 3000 2 0.5 0.005
SLC 2x10 30 120 1 4 1.5 0.5LEP II 5x10 31 10 000 8 30 240 4LEP-II 5x10 10,000 8 30 240 4PEP-II 1x10 34 140,000 1700 6 155 4
ILC-ECFA WorkshopWarsaw, 9 June 2008
Carlo Pagani23
Start of the Global Design Initiative
~ 220 participants from 3 regionsmost of them accelerator experts
ILC-ECFA WorkshopWarsaw, 9 June 2008
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ILC Pictorial View (TESLA Like)
A t th T h l R d ti ti
ILC-ECFA WorkshopWarsaw, 9 June 2008
Carlo Pagani25
As at the Technology Recommendation time
The Existing FLASH @ DESY
ILC-ECFA WorkshopWarsaw, 9 June 2008
Carlo Pagani26
European Industrial Forum for SCRFp3
.fr/
SCRF
trac
.lal.in2
pht
tps:
//t
ILC-ECFA WorkshopWarsaw, 9 June 2008
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https://indico.desy.de/conferenceTimeTable.py?confId=61
Designing a Linear Collider
source
pre-acceleratorfew GeV
dampingring
final focus
extraction& dump
KeV
few GeVfew GeV
250-500 GeV
main linacbunchcompressor collimation
final focus
IP
few GeV
compressor collimation
Superconducting RF Main Linac
ILC-ECFA WorkshopWarsaw, 9 June 2008
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ILC Road Map
ILC-ECFA WorkshopWarsaw, 9 June 2008
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Conclusions
Present and future large facilities are based to a large extent on the superconducting RF linac technology that has been pioneered for the High Energy Physics machines in the last decadesHigh Energy Physics machines in the last decades
– LEP at CERN (e+e- collider with SRF cavities)– CEBAF at TJNAF (recirculated SRF linac)– TESLA and ILC (next generation linear colliders proposed for
precision physics in the Higgs sector after LHC discovery)
SNS moved from NC design to SC after project approval and during construction
Future facilities rely on SC linacs at even lower energies to benefit from SC technology
ILC-ECFA WorkshopWarsaw, 9 June 2008
Carlo Pagani30
Energy Frontier and e+e- Colliders
LEP at CERNEcm ~ 200 GeVLEP at CERNEcm ~ 200 GeVcmPRF ~ 30 MW
cmPRF ~ 30 MW
ILC
ILC-ECFA WorkshopWarsaw, 9 June 2008
Carlo Pagani31
Energy Frontier and Accelerator Tech.
Superconducting Magnets
ILC
Superconducting RF Cavities
LHC Dipole String
ILC-ECFA WorkshopWarsaw, 9 June 2008
Carlo Pagani32
LEPII Cavity String