The International Linear Collider as a Global …...SRF Thin Film Workshop 12 October 2006 Carlo...

SRF Thin Film Workshop 12 October 2006

Carlo Pagani 1

The International Linear Collider as a Global Technology Challenge

Carlo PaganiUniversity of Milano

INFN Milano-LASA & GDE

The International Workshop on:Thin Films and new ideas for

pushing the limits of RF superconductivityOctober 9-12, 2006

INFN Legnaro National Laboratory INFN Padua, Italy


Carlo Pagani 2

Energy Frontier and e+e- Colliders

LEP at CERNEcm ~ 200 GeVPRF ~ 30 MW

LEP at CERNEcm ~ 200 GeVPRF ~ 30 MW

ILC


Carlo Pagani 3

No Circular e+e- Collider after LEP

B

Synchrotron Radiation:charged particle in a magnetic field:

Energy loss replaced by RF powercost scaling $ ∝ Ecm

2

[ ] [ ]kmr1106GeV 421 ⋅⋅⋅= − γSRU

USR = energy loss per turnγ = relativistic factorr = machine radius

Energy loss dramatic for electrons

γproton / γelectron ≈ 2000


Carlo Pagani 4

A Simple Exercise

Synchrotron Radiation (SR) becomes prohibitive for electrons in a circular machine above LEP energies:

RF system must replace this loss, and r scale as E2

LEP @ 100 GeV/beam: 27 km around, 2 GeV/turn lostPossible scale to 250 GeV/beam i.e. Ecm = 500 GeV:– 170 km around– 13 GeV/turn lost

Consider 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

Both size and power seem excessive

[ ] [ ]kmr1106GeV 421 ⋅γ⋅⋅= −

SRUUSR = energy loss per turnγ = relativistic factorr = machine radius

γ250GeV = 4.9 . 105

Circulating beam power = 500 GW


Carlo Pagani 5

Origin of the Linear Collider Idea

A Possible Apparatus for Electron-Clashing Experiments (*).

M. TignerLaboratory of Nuclear Studies. Cornell University - Ithaca, N.Y.

M. Tigner, Nuovo Cimento 37 (1965) 1228

“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 other methods which, while less elegant and superficially more complex may prove more tractable.”


Carlo Pagani 6

LC conceptual scheme

Electron GunDeliver stable beam current

Damping RingReduce transverse phase space (emittance) so smaller transverse IP size achievable

Bunch CompressorReduce σz to eliminate hourglass effect at IP

Positron TargetUse electrons to pair-produce positrons

Main LinacAccelerate beam to IP energy without spoiling DR emittance

Final FocusDemagnify and collide beams


Carlo Pagani 7

Fighting for Luminosity

yx

e

c.m.

b

σσN

EPL ×∝

Parameters to play withReduce beam emittance (εx

.εy ) for smaller beam size (σx.σy )

Increase bunch population (Ne )Increase beam powerIncrease beam to-plug power efficiency for cost

nb = # of bunches per pulse

frep = pulse repetition rate

Pb = beam power

Ec.m.= center of mass energy

L = Luminosity

Ne = # of electron per bunch

σx,y = beam sizes at IP

IP = interaction point

( )repbb fnNP ××∝ e

yx

2e

σσNL ∝ xσ

yσrepb fnL ×∝


Carlo Pagani 8

Beam Sizes

© M. Tigner


Carlo Pagani 9

Linacs are made of RF cavities

To give energy to a charged particle beam, apart from “details”, you need to let him move across a region in which an electric field exists and is directed as the particle motion.

In the accelerator’s world RF take care of all the variety of items that are required to accomplish this task of creating a region filled of electromagnetic energy that can be sucked by the beam while crossing it. An “RF power source” is used to fill, via a “coupler”, the “RF cavity”, or resonator that is the e.m. energy container from which the beam is taking its energy. What we ask to a good cavity?

dtvEqsdFE Lorentzparticlerrrr⋅=⋅=Δ ∫∫

dissPUQ ω=

High Q for losses:U = stored energyPdiss = dissipated power sR

GQ =Small Rs for high Q:Rs = surface resistance G = cavity geometrical factor


Carlo Pagani 10

The ILC technology choice

π mode

Standing wave: Vph = 0 and Vg = c

TESLA: f = 1.3 GHz

Remembering that the power dissipated on the cavity walls to sustain a field is:

∫=S

sdiss dSHRP 2

2a pulsed operation is required to reduce the time in which the maximum allowable field is produced to accelerate the particles

standing wave case

1.0E-08

1.0E-07

1.0E-06

1.0E-05

1.0E-04

1.0E-03

0 500 1000 1500 2000 2500 3000

f [MHz]

Rat

io b

etw

een

Nb

and

Cu

Rs

2 K4.2 K

The power is deposited at the operating temperature of 2 K

We need to guarantee and preserve the 2 K environment

Cavity is sensitive to pressure variations, only viable environment issub-atmospheric vapor saturated He II bath

We need a thermal “machine” that performs work at room temperature to extract the heat deposited at cold

We can’t beat Carnot efficiency! Cryogenics and cryomodules


Carlo Pagani 11

How is spent the cold advantage?

The gain in RF power dissipation with respect to a normal-conducting structure is spent in different ways

Paying the price of supplying coolant at 2K– This include ideal Carnot cycle efficiency– 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)– Good for Luminosity

c

ch

TTT

QW−

≥


Carlo Pagani 12

LCs are pulsed machines to improve efficiency. As a result: • duty factors are small• pulse peak powers can be very large

RF Pulse

Bunch Train

Beam Loading

<10-200 ms

<1 µs-1ms

1-300 nsec100 m - 300 km

…………………....……

gradientwith further input

without input

filling loading

accelerating field pulse:

Linear Colliders are pulsed


Carlo Pagani 13

SRF before TESLA“Livingston Plot” from Hasan Padamsee


Carlo Pagani 14

Large Project Impact on SRF

The decision of applying this unusual technology in the largest HEP and NP accelerators forced the labs to invest in Research & Development, infrastructures and quality controlThe experience of industry in high quality productions has been taken as a guideline by the committed labs At that time TJNAF and CERN played the major role in SRF development, mainly because of the project sizeThe need of building hundreds of cavities pushed the labs to transfer to Industry a large part of the productionThe large installations driven by HEP and NP produced a jump in the fieldR&D and basic research on SRF had also a jump thanks to the work of many groups distributed worldwide

LEP

CEBAF


Carlo Pagani 15

CEBAF and LEP II

LEP II & CERN

32 bulk niobium cavitiesLimited to 5 MV/mPoor material and inclusions

256 sputtered cavitiesMagnetron-sputtering of Nb on CuCompletely done by industryField improved with time<Eacc> = 7.8 MV/m (Cryo-limited)

352 MHz, Lact=1.7 m

1.5 GHz, Lact=0.5 m5-cell cavities

4-cell cavities

CEBAF

338 bulk niobium cavitiesProduced by industryProcessed at TJNAF in adedicated infrastructure


Carlo Pagani 16

A great success for LEP II

0

5

10

15

20

25

30

4 4.2 4.4 4.6 4.8 5 5.2 5.4 5.6 5.8 6 6.2 6.4 6.6 6.8 7 7.2 7.4 7.6 7.8 8 8.2 8.4 8.6 8.8 9 9.2 9.4

Accelerating field [MV/m]

Num

ber o

f cav

ities

96 GeV100 GeV104 GeV

96 GeV:Mean Nb/Cu6.1 MV/m

100 GeV: 3500MVMean Nb/Cu6.9 MV/m 104 GeV: 3666MV

Mean Nb/Cu7.5 MV/m

design

Accelerating Field Evolution with time Final energy reachlimited by

allowable cryogenic powerfrom G. Geschonke’s Poster for the ITRP visit to DESY


Carlo Pagani 17

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)• 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 Technology• Higher conversion efficiency: more beam power for less plug power consumption• Lower RF frequency: relaxed tolerances and smaller emittance dilution

as in 1992

Björn Wiik


Carlo Pagani 18

TESLA cavity design and rules

Hz/(MV/m)2≈ -1KLorentz

kHz/mm315Δf/Δl

mT/(MV/m)4.26Bpeak/Eacc

2.0Epeak/Eacc

Ω1036R/Q

TESLA cavity parameters

- Niobium sheets (RRR=300) are scanned by eddy-currents to detect avoid foreign

material inclusions like tantalum and iron

- Industrial production of full nine-cell cavities:

- Deep-drawing of subunits (half-cells, etc. ) from niobium sheets

- Chemical preparation for welding, cleanroom preparation

- Electron-beam welding according to detailed specification

- 800 °C high temperature heat treatment to stress anneal the Nb

and to remove hydrogen from the Nb

- 1400 °C high temperature heat treatment with titanium getter layer

to increase the thermal conductivity (RRR=500)

- Cleanroom handling:

- Chemical etching to remove damage layer and titanium getter layer

- High pressure water rinsing as final treatment to avoid particlecontamination

Figure: Eddy-current scanning system for niobium sheets Figure: Cleanroom handling of niobium cavities

9-cell, 1.3 GHz

Major contributions from: CERN, Cornell, DESY, CEA-Saclay, INFN


Carlo Pagani 19

TTF: a new infrastructure at DESY

TTF as operated for SASE FEL


Carlo Pagani 20

Eddy Current Scanner for Nb Sheets

Scanning results

Rolling marks and defects are visible on a niobium disk to be used to print a cavity half-cell. Surface analysis is then required to identify the inclusions


Carlo Pagani 21

Cavity Production: EB welding and QC


Carlo Pagani 22

Chemistry, HPR and String Assembly


Carlo Pagani 23

Learning curve with BCP

3 cavity productions from 4 European industries: Accel, Cerca, Dornier, Zanon4th production of 30 cavities concluded, also to define Quality Control for Industrialization

BCP = Buffered Chemical Polishing

Module performance in the TTF LINAC

Improved weldingNiobium quality control

<Eacc> @ Q0 ≥ 1010 <Eacc> @ Q0 ≥ 1010

<1997>

<1999>

<2001>


Carlo Pagani 24

3rd cavity production with BCP

1E+09

1E+10

1E+11

0 10 20 30 40Eacc [MV/m]

Q0

AC55 AC56AC57 AC58AC59 AC60AC61 AC62AC63 AC64AC65 AC66AC67 AC68AC69 AC79

1011

109

1010

3rd Production - BCP CavitiesStill some field emission at high fieldQ-drop above 20 MV/m not cured yetJust AC67 discarded (cold He leak)

TESLA original goal

Vertical CW tests of naked cavitis

Q-drop


Carlo Pagani 25

EP & Baking for 35 MV/m

Electro-Polishing (EP)instead of

Buffered Chemical Polishing (BCP)• less local field enhancement• High Pressure Rinsing more effective • Field Emission onset at higher field

In Situ Baking

@ 120-140 ° C for 24-48 hours

• to re-distribute oxygen at the surface

• cures Q drop at high field

EP at the DESY plant• Low Field Emission 800°C annealing

120°C, 24 h, Baking• high field Q drop curedHigh Pressure Water Rinsing

Vertical and System Test in 1/8th CryomoduleThe AC 70 example


Carlo Pagani 26

Performing Cryomodules

Required plug power for static losses < 5 kW/(12 m module)

Reliable Alignment Strategy

Sliding Fixtures @ 2 K

“Finger Welded” Shields

Three cryomodule generations to:improve simplicity and performances minimize costs


Carlo Pagani 27

LCH and ILC Module Comparison

From an LHC Status Report by Lyndon R. Evans

ACC 4 & ACC 5 in TTF ACC 2 & ACC 3 in TTF

∅ = 38”

∅ = 38” ∅ = 42”


Carlo Pagani 28

Competing technologies

30 GHz-Warm

11.4 GHz - Warm

1.3 GHz - Cold


Carlo Pagani 29

LC Organisation up to August 2004


Carlo Pagani 30

LC status at second ILC-TRC

3

4

195

6.9

20

11.4

JLC-X/NLC VLEPP

1.245σy* [nm]

143γεy [×10-

8m]

175233140PAC [MW]

4.95.811.3Pbeam [MW]

211434L×1033 [cm-

2s-1]

30.05.71.3f [GHz]

CLICJLC-C

JLC-SSBLCTESL

A

January 2003 Ecm= 500 GeV


Carlo Pagani 31

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:

Mission: one technology by end 2004

Result: recommendation on 19 August 2004

Asia:G.S. LeeA. MasaikeK. OideH. Sugawara

Europe:J-E AugustinG. BellettiniG. KalmusV. Soergel

North America:J. Bagger B. Barish (Chair)P. GrannisN. Holtkamp

First meeting end of January 2004 at RAL


Carlo Pagani 32

Departing from Korea

From the ILC Birthday


Carlo Pagani 33



Carlo Pagani 34



Carlo Pagani 35

From the Day After

Robert Aymar (CERN): “A linear collider is the logical next step to complement the discoveries that will be made at the LHC. The technology choice is an important step in the path towards an efficient development of the international TeV linear collider design, in which CERN will participate.”Yoji Totsuka (KEK): “This decision is a significant step to bring the linear collider project forward. The Japanese high-energy community welcomes the decision and looks forward to participating in the truly global project.”Jonathan Dorfan (SLAC): “Scientific discovery is the goal. Getting to the physics is the priority. The panel was presented with two viable technologies. We at SLAC embrace the decision and look forward to working with our international partners.”

Similar Declarations from: Albrecht Wagner (DESY), Hesheng Chen (HEP), Michael Witherell (FNAL) et al.

From the ICFA press release, Beijing, 20 August 2005


Carlo Pagani 36

ILC Pictorial View


Carlo Pagani 37

Start of the Global Design Initiative

~ 220 participants from 3 regionsmost of them accelerator experts


Carlo Pagani 38

Global SCRF Test Facilities for ILC

TESLA Test Facility (TTF II) @ DESYTTF II is currently unique in the worldVUV-FEL user facility (now called FLASH)test-bed for both XFEL & ILCCryomodule Test Stand under commissioning

SMTF @ FNALCornell, JLab, ANL, FNAL, LBNL, LANL, MIT,MSU, SNS, UPenn, NIU, BNL, SLACTF for ILC, Proton Driver, RIA (and more)

STF @ KEKaggressive schedule to produce high-gradient(45MV/m) cavities / cryomodules

Others?


Carlo Pagani 39

feed cap

end cap cryomodule

supports

feed box

feed cap transfer line

Cryomodule Test Stand @ DESY

Commissioning in these days


Carlo Pagani 40

STF @ KEK


Carlo Pagani 41

SMTF @ FNAL as presented to DOE

“The SMTF proposal is to develop U.S. Capabilities in high gradient and highQ superconducting accelerating structures

in support of

International Linear ColliderProton Driver

RIA4th Generation Light Sources

Electron coolerslepton-heavy ion colliderand other accelerator

projects of interest to U.S and the world physics

community.”


Carlo Pagani 42

Global Design Effort (GDE)

On March 18, 2005, during the opening of LCWS05 workshop at Stanford University, Barry Barish officially accepted the position of Director of the Global Design Effort, GDE (yet to be formed)


Carlo Pagani 43

GDE Actual Members

49 67


Carlo Pagani 44

The 2nd ILC Workshop


Carlo Pagani 45

Produce a design for the ILC that includes a detailed design concept, performance assessments, reliable international costing, an industrialization plan , siting analysis, as well as detector concepts and scope.

Coordinate worldwide prioritized proposal driven R & D efforts (to demonstrate and improve the performance, reduce the costs, attain the required reliability, etc.)

The Mission of the GDE

© Barry Barish


Carlo Pagani 46

Parametric Approach

A working space - optimize machine for cost/performance


Carlo Pagani 47

main linacbunchcompressor

dampingring

source

pre-accelerator

collimation

final focus

IP

extraction& dump

KeV

few GeV

few GeVfew GeV

250-500 GeV

Superconducting RF Main Linac

Designing a Linear Collider


Carlo Pagani 48

Luminosity & Beam Size

frep * nb tends to be low in a linear collider

The beam-beam tune shift limit is much looser in a linear collider than astorage rings achieve luminosity with spot size and bunch charge– Small spots mean small emittances and small betas:

– σx = sqrt (βx εx)

Dyx

repb HfNn

Lσπσ2

2

=

L frep [Hz] nb N [1010] σx [μm] σy [μm]ILC 2x1034 5 3000 2 0.5 0.005SLC 2x1030 120 1 4 1.5 0.5LEP2 5x1031 10,000 8 30 240 4PEP-II 1x1034 140,000 1700 6 155 4


Carlo Pagani 49

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

~ 5 nm

InteractionPoint (IP)

Achieving High Luminosity


Carlo Pagani 50

Many decisions are interrelated and require input from several WG/GG groups

Making Choices – The Tradeoffs


Carlo Pagani 51

August September October November December

2005Snowmass

WW/GG summaries

Response to list of 40+ decisions

All documented ‘recommendations available on ILC Website (request community feedback)

Review by BCD EC BCD EC publishes‘strawman’ BCD

PublicReview

Frascati GDE meeting

BCD Executive Committee:BarishDugan, Foster, Takasaki Raubenheimer, Yokoya, Walker

© Barry Barish

From Snowmass to a Baseline


Carlo Pagani 52

not to scale

~31 km

RTML ~1.6km

20mr

2mr BDS 5km

ML ~10km (G = 31.5MV/m)

x2e+ undulator @ 150 GeV (~1.2km)R = 955m

E = 5 GeV

The Baseline Machine


Carlo Pagani 53

Baseline Configuration Document

GDE ‘Deliverable’ by the end of 2005

A structured electronic document– Documentation (reports, drawings etc)– Technical specs.– Parameter tables

http://www.linearcollider.org/wiki/doku.php?id=bcd:bcd_home


Carlo Pagani 54

Summary-like overview for those who want to understand the choice and the why

Technical documentationof the baseline, for engineers and acc. phys. making studies towards RDR

Structure of the BCD


Carlo Pagani 55

ACD is part of the BCD

Alternatives Section


Carlo Pagani 56

Baseline/Alternative: some definitions

Baseline: a forward looking configuration which we are reasonably confident can achieve the required performance and can be used to give a reasonably accurate cost estimate by mid-end 2006 (→ RDR)

Alternate: A technology or concept which may provide a significant cost reduction, increase in performance (or both), but which will not be mature enough to be considered baseline by mid-end 2006

Note:Alternatives will be part of the RDRAlternatives are equally important


Carlo Pagani 57

Creating a Reference Design

The BCD is now being used as the basis for the reference design / cost effort this year.

It is being evolved through a formalized change control process

Our goal is to produce a consistent design for the ILC, capable of delivering design performance.

We have been trying to contain costs for the basic machine, while determining costs on an “international basis.”

The design will continue to evolve following the RDR, as the R&D provides more CCB actions.


Carlo Pagani 58

GDE Organization for RDR

Selected some selected new members for the GDE following the BCD completion who have needed skills in design, engineering, costing, etcChange Control Board– The baseline will be put under configuration control and a

Board with a single chair will be created with needed expertise.

Design / Cost Board– A GDE Board with single chair will be established to coordinate

the reference design effort, including coordinating the overall model for implementing the baseline ILC, coordinating the design tasks, costing, etc.

R&D Board– A GDE Board will be created to evaluate, prioritize and

coordinate the R&D program in support of the baseline and alternatives with a single chair


Carlo Pagani 59

Jan July Dec 2006

Freeze ConfigurationOrganize for RDR

Bangalore

Review Design/Cost Methodology

Review InitialDesign / Cost Review Final

Design / CostRDR Document

Design and CostingPreliminary

RDRReleased

Frascati Vancouver Valencia

From Baseline to a RDR


Carlo Pagani 60

Two tunnels• accelerator units• other for services - RF power

~30 km long tunnel

Particle DetectorMain Research Center

Linear Collider Facility


Carlo Pagani 61

SRF Cavity Gradient

LL

TESLA

Cavity type

GeVKmMV/mMV/m

500+9.336.040upgrade

25010.631.535initial

energyLength*Operational gradient

Qualifiedgradient

(* assuming 75% fill factor)Total length of one 500 GeV linac ≈ 20km


Carlo Pagani 62

500 GeV BCD machine + “essentials” for 1 TeV

Follow ITER “Value” & CERN “CORE” model for International Projects– Provides basic agreed to costs [common “value”+ in-house

labor (man-hr)]

RDR will provide information for translation into any country’s cost estimating metric, e.g. Basis of Estimate => contingency estimate, in-house labor, G&A, escalation, R&D, pre-construction, commissioning, etc.

Assumes a 7 year construction phase

RDR Cost Estimating


Carlo Pagani 63

Design Status and Plans– Baseline was determined and documented at end of 2005– Plan to complete reference design / cost by the end of 2006– Technical design by end of 2009

R & D Program– Support baseline: demonstrations; optimize cost / perfomance;

industrialization– Develop improvements to baseline – cavities; high power RF

Overall Strategy– Be ready for an informed decision by 2010– Siting; International Management; LHC results; CLIC feasibility

etc

Remarks on GDE Work


Carlo Pagani 64

Summary

The ILC is ambitious project which pushed the envelope in every subsystem:– Main SCRF linac– sources– damping rings– beam delivery

Still many accelerator physics issues to deal with, but reliability and cost issues are probably the greater challenge

Probably in excess of 3000 man-years already invested in design work.

ILC performance bottleneck

cost driver

The International Linear Collider as a Global …...SRF Thin Film Workshop 12 October 2006 Carlo...

Documents

Transcript of The International Linear Collider as a Global …...SRF Thin Film Workshop 12 October 2006 Carlo...