A Report from Snowmass on

ILC

F. Cervelli INFN-Pisa

The ILC will consist in two facing linear accelerators, each 20 kilometers long, hurling beams of electrons and positrons toward each other at nearly the speed of light. Each beam contains ten billion electrons or positrons compressed to a minuscule three-nanometer thickness. Particles are accelerated by superconducting cavities.The energy of the ILC's beam can be adjusted to home in on processes of interest.

The Internatonal Linear Collider

The Physics

Higgs Coupling and Extra Dimensions• ILC precisely measures Higgs interaction strength with standard model particles.

• Straight blue line gives the standard model predictions.

• Range of predictions in models with extra dimensions -- yellow band, (at most 30% below the Standard Model)

• The models predict that the effect on each particle would be exactly the same size.

• The red error bars indicate the level of precision attainable at the ILC for each particle

• Sufficient to discover extra dimensional physics.

The Strategy

Snowmass Workshop – Aug 2005

Snowmass represents the kickoff of what we all hope will be a successful and truly international process to design and then build the next great particle accelerator !!!

Global Design Effort

The Mission of the GDE 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.)

main linacbunchcompressor

dampingring

source

pre-accelerator

collimation

final focus

IP

extraction& dump

KeV

few GeV

few GeVfew GeV

250-500 GeV

Starting Point for the GDE

Superconducting RF Main Linac

Parameters for the ILC

Ecm adjustable from 200 – 500 GeV

Luminosity ∫Ldt = 500 fb-1 in 4 years

Ability to scan between 200 and 500 GeV

Energy stability and precision below 0.1%

Electron polarization of at least 80%

The machine must be upgradeable to 1 TeV

Design ApproachCreate a baseline configuration for the machine Document a concept for ILC machine with a complete layout,

parameters etc. defined by the end of 2005 Make forward looking choices, consistent with attaining

performance goals, and understood well enough to do a conceptual design and reliable costing by end of 2006.

Technical and cost considerations will be an integral part in making these choices.

Baseline will be put under “configuration control,” with a defined process for changes to the baseline.

A reference design will be carried out in 2006. I am proposing we use a “parametic” design and costing approach.

Technical performance and physics performance will be evaluated for the reference design

Approach to ILC R&D Program

Proposal-driven R&D in support of the baseline design. Technical developments, demonstration experiments,

industrialization, etc.

Proposal-driven R&D in support of alternatives to the baseline Proposals for potential improvements to the baseline,

resources required, time scale, etc.

Develop a prioritized DETECTOR R&D program aimed at technical developments needed to reach combined design performance goals

GDE – Near Term Plan

Schedule Begin - define Configuration (Snowmass Aug 05) Baseline Configuration Document (end of 2005)

----------------------------------------------------------------------- Baseline under Configuration Control (Jan 06) Develop Reference Design (end of 2006) Coordinate the supporting R&D program

Three volumes -- 1) Reference Design Report; 2) Shorter glossy version for non-experts and policy makers ; 3) Detector Concept Report

The GDE Plan and Schedule 2005 2006 2007 2008 2009 2010

Global Design Effort Project

Baseline configuration

Reference Design

ILC R&D Program

Technical Design

Bids to Host; Site Selection;

International Mgmt

LHCPhysics

Cost Breakdown by Subsystem

cf31%

structures18%rf

12%

systems_eng8%

installation&test7%

magnets6%

vacuum4%

controls4%

cryo4%

operations4%

instrumentation2%

Civil

SCRF Linac

Three concepts under study

Typically requires factors of two or so improvements in granularity, resolution, etc. from present generation detectors

Focused R&D program required to develop the detectors -- end of 2005

Detector Concepts will be used to determine machine detector interface, simulate performance of reference design vs physics goals next year.

Detector Concepts and Challenges

ILCCommunications

Launch New ILC Website www.linearcollider.org

thanks to Norm Graf for url

“One Stop Shopping”electronic data management system (EDMS), news, calendar of events, education and communication,

Designer Xeno Media (Kevin Munday)

GDE Process and Meetings

Snowmass (Aug 05) first meetingsFrascati (Dec 7-10, 2005) (in conjunction with TESLA collaboration meeting)Bangalore, India (March 2006) (in conjunction with LCWS 2006)

Our process and meetings will be open! Our website will post all progress, developments, issues and decisions. We invite community input and participation at each step.

The Detectors

In order to accomplish our physics goal at ILC

With respect to detectors at LHC:

■Inner VTX layer 3--6 times closer to IP■VTX pixel size 1 / 30■VTX materials 1 / 30

■Materials in Tracker 1 / 6■Track mom. resolution 1 / 10

■EM cal granularity 1 / 200 !!

ILC Detector Challenges

PFA (Particle Flow Algorithm) at the ILC

Jet energy resolution is the key in ILC physicsThe best jet energy resolution is obtained by reconstructing momenta of individual particles avoiding double counting among Trackers and Calorimeters Charged particles (~60%) measured by Tracker Photons (~30%) by Electromagnetic CAL (ECAL) Neutral hadrons (10%) by ECAL+Hadron CAL (HCAL)

Particle Flow AnalysisTo get good jet energy resolution by PFA: Separation of particles (reducing the density of charged and neutral particles at CAL surface) is important for PFA :

Fine segmentation of CAL High B field Large CAL radius

The Accelerator Complex

Design Choices for Baseline

Design Alternatives Gradient / Length (30MV/m?, 35MV/m? Higher?) Tunnel (single? or double?) Positron Souce (undulator? conventional?) Damping ring (dogbone? small ring?) Crossing angle (head-on, small angle, large angle)

Define detailed configuration RF layout Lattice layout Beam delivery system layout Klystron / modulators Cryomodule design

Evolve these choices through “change control” process

ILC Siting and Civil Construction

The design is intimately tied to the features of the site 1 tunnels or 2 tunnels? Deep or shallow? Laser straight linac or follow earth’s curvature in

segments?

GDE ILC Design will be done to samples sites in the three regions North American sample site will be near Fermilab Japan and Europe are to determine sample sites

by the end of 2005

1 vs 2 TunnelsTunnel must contain Linac Cryomodule RF system Damping Ring Lines

Save maybe $0.5B

Issues Maintenance Safety Duty Cycle

The Working Groups

Snowmass – GDE Groups

WG1 – Items to be Completed

Recommendation of a Bunch Compressor configuration (1 stage, 2 stage…)Recommendation of a main linac configuration (with WG2, WG5, and GG4) quad spacing cavities per cryomodule quads in RF cryomodules or separate ones straight, bent, or curved tunnel Consider one recommendation for TTC Cavity, and a

separate one for low-loss / high-gradient / high wakefield cavity?

WG1 Goals for Snowmass (2)

Agreement on nominal and “operating plane” beam parameters for LET and IP (with GG1)Agreement on a plan and schedule for completion of work from now until end 2006 Studies for BCD Studies for RDR

Development of some “nuts and bolts” standards for exchange of technical information deck formats and repository, etc.

Topics covered by WG2

RF wave-guide distribution Modulators / klystrons Low Level RF Beam interfaces (quadrupoles, BPM’s) Cryomodule Cryo-systems

Important interfaces with other WG’s especially WG5

FNAL-Based SMTF Proposal: “It is anticipated that, with coordination from the ILC-Americas collaboration, SLAC will lead the ILC rf power source efforts ...

Focus of Efforts at JLab and FNAL

Focus of Efforts at SLAC

Gradient

Baseline recommendation for cavity is standard TESLA 9-cell

Alternatives (energy upgrade): Low-loss, Re-entrant superstructure

ILC KlystronDevelopment

Baseline Klystrons

Thales CPI Toshiba

Specification:

10MW MBK

1.5ms pulse

65% efficiency

New Cryomodule Test Facilities

SMTF at FNAL

STF at KEK

CMTB at DESY

Existing TTF modules remain important means of test (alignment, vibration….).

1.3 GHz ILC Cryomodule

4 Cavities US Built/purchased

4 Cavities KEK Built/US processed

Main Goal: Develop U.S. Capabilities in fabricating and operating with Beam Superconducting accelerating cavities and cryomodule in support of the International Linear Collider.

High gradient (35 MV/m or Greater) and high Q (~0.5-1e10)

Superconducting Module Test Facility (SMTF) at FNAL

XFEL Test Hall Layout

WG3a: ILC Sources: Electrons and Positrons

Working Group 3b: Damping Rings

room-temperature accelerating sect.

diagnostics section

standard ILC SCRF modules

DC gun(s)

sub-harmonic bunchers + solenoids

laser

ILC polarized electron source (PES) - possible baseline -

Laser requirements:pulse energy: ~ 2 Jpulse length: ~ 2 ns# pulses/train: 2820Intensity jitter: < 5 % (rms)pulse spacing: 337 nsrep. rate: 5 Hzwavelength: 750-850 nm

DC gun:>120 keV HV (TDR) VHV gun? JLab, Cornell, Nagoya

Room temperature linac:Allows external focusing by solenoidsSame as e+ capture linac

photocathodes:GaAs/GaAsP

Conventional Non-Polarized Positrons

Undulator-Based Polarized Positrons (Undulator Option 2)

Compton experiment at ATF Polarized ee++

Source for ILC

Polarized Positron Production: Compton Scheme: CO2 Version (Omori, et al.)

Positron SourceUndulator source

Uses main electron beam (150-250 GeV) Coupled operation Efficient source Relatively low neutron activation Polarisation

Laser Compton source Independent polarised source Relatively complex source Multi-laser cavity system required Damping ring stacking required Large acceptance ring (for stacking) Needs R&D

Conventional Source Single target solution exists Close to (at?) limits Independent source

WG3a recommendation for baseline

Will need ‘keep alive source’ due reliability issues

WG3a recommended alternative.

Strong R&D programme needed

Currently on-hold as a backup solution

Pre-damping ring not required

Damping Rings: Three variants

3km

6km

17 km ‘dogbone’

Damping Rings

bunch train compression300km 20km

smaller circumference(faster kicker)

higher Iav

Damping ring designs must be relatively conservative

“The SLC experience emphasized the importance of low particle losses and the suppression of collective instabilities [in the damping rings].Beam instability and jitter can … make the machine inoperable.”

(ILC-TRC Second Report, 2003, p.304)

The beam is stored for a relatively long time in the damping rings, where it is sensitive to a wide range of destabilizing effects.

The SLC experience was that even very small effects in the damping rings were amplified in the downstream systems and had a big impact on the overall machine performance.

If other systems in the ILC are to be technically ambitious, the damping ring designs must be relatively conservative.

ILC DR kicker – preparation for BCD decision

Input from WG3b: Kicker specs: (long list) geometry, field, uniformity (sextupole), N,

impedance Rise time, rate, fall time, droop, stability, reliability

To Do items for TF5: Develop present (baseline C. D.) design:

Naito’s specification 1) Performance improvement of the pulser (the rise

time, the droop within the pulse train, the repetition rate, etc.) (not only FID pulser).

2) Beam kick test with complementary pulse 3) Kick angle stability measurement by the beam 4) Design and fabrication of the optimized strip line

electrode 5) Consider the 6MHz, 6000 (?) pulses operation

ILC WG4

Every thing after Main LinacBeam delivery Interaction regionBeam diagnosticsFeedback systemBeam dump …

Beam Delivery, MDI

Strawman solution (BCD recommendation)

Appears to work for nearly all suggested parameter sets:Exceptions:• 1 TeV high-luminosity (new parameter set suggested for 20mrad)• 2 mrad extraction has problems with high disruption sets

TESLA Cavity

9-cell 1.3GHz Niobium Cavity

Reference design: has not been modified in 10 years

~1m

Gradient

How Costs Scale with Gradient?

Relative

Co

st

Gradient MV/m

2

0

$ lincryo

a Gb

G Q

35MV/m is close to optimum

Japanese are still pushing for 40-45MV/m

30 MV/m would give safety margin

C. Adolphsen (SLAC)

The Hard Questions

Organization

Transition to the GDE

Three regional directors have identified GDE members (with agreement from BB)49 (current) members representing approximately 20 FTEGDE group consists of core accelerator physics experts 3 CFS experts (1 per region) 3 costing engineers (1 per region) 3 communicators (1 per region) representatives from WWS

Chris Adolphsen, SLAC*Jean-Luc Baldy, CERN*Philip Bambade, LAL, OrsayBarry Barish, Caltech (the boss)Wilhelm Bialowons, DESY*Grahame Blair, Royal Holloway*Jim Brau, University of OregonKarsten Buesser, DESYElizabeth Clements, FermilabMichael Danilov, ITEPJean-Pierre Delahaye, CERN (EU dep. dir.)Gerald Dugan, Cornell University (US dir.)Atsushi Enomoto, KEK*Brian Foster, Oxford University (EU dir.)Warren Funk, JLABJie Gao, IHEP*Terry Garvey, LAL-IN2P3*Hitoshi Hayano, KEK*Tom Himel, SLAC*Bob Kephart, Fermilab*Eun San Kim, Pohang Acc LabHyoung Suk Kim, Kyungpook Nat’l UnivShane Koscielniak, TRIUMFVic Kuchler, Fermilab*Lutz Lilje, DESY*

Tom Markiewicz, SLACDavid Miller, Univ College of LondonShekhar Mishra, FermilabYouhei Morita, KEKOlivier Napoly, CEA-SaclayHasan Padamsee, Cornell UniversityCarlo Pagani, DESYNan Phinney, SLACDieter Proch, DESY*Pantaleo Raimondi, INFNTor Raubenheimer, SLAC*Francois Richard, LAL-IN2P3Perrine Royole-Degieux, GDE/LALKenji Saito, KEK*Daniel Schulte, CERN*Tetsuo Shidara, KEKSasha Skrinsky, Budker InstituteFumihiko Takasaki, KEKLaurent Jean Tavian, CERNNobu Toge, KEKNick Walker, DESY (EU dep. dir.)*Andy Wolski, LBL*Hitoshi Yamamoto, Tohoku UnivKaoru Yokoya, KEK*

49 members

* workshop WG/GG convener

Gradient

How Costs Scale with Gradient?

Relative

Co

st

Gradient MV/m

2

0

$ lincryo

a Gb

G Q

35MV/m is close to optimum

Japanese are still pushing for 40-45MV/m

30 MV/m would give safety margin

C. Adolphsen (SLAC)

Configuration Parameter Space

GOALSPhysics and Detector

WorkshopTo develop the Linear Collider detector studies with precise understanding of the technical details and physics performance of candidate detector concepts, as well as the required future R&D, test beam plans, machine-detector interface and beamline instrumentation, cost estimates, and other aspects.

GOALSPhysics and Detector

Workshop

To advance the Linear Collider physics studies, including precision calculations, synergy with the LHC, connections to cosmology and astrophysics, and relationships to the detector design studies.

GOALSPhysics and Detector

Workshop

To facilitate and strengthen the broad participation of the community in Linear Collider physics, detectors, and accelerators, and engage the greater public in the excitement of this work.

Cryomodule : Cryostat Design

35MV/m TESLA design cavities (4)

45MV/m Low-loss cavities (4)

Weld connection

Valve Box Two cryostat connection, 4 cavities in one cryostat.

Eventually 8 cavities in one cryostatLike TTF cryomodule

Key issues for the configuration selection

Beam dynamics Acceptance must be large enough to allow excellent

injection efficiency. Extreme levels of beam stability are needed. Ultra-low vertical emittance must be achieved on a routine

basis. Beam polarization must be maintained.

CostOperability Rapid commissioning must be possible. High levels of reliability must be achieved. Flexibility is desirable.

Variations in fill pattern, bunch charge… Damping rings should be upgradeable.

The GLD Concept

GLD detector concept1. Large inner radius of ECAL to optimize for PFA (jet

reconstruction)

– Use fine-segmented W-Scintillator ECAL for cost efficiency

2. Large gaseous tracker

– for excellent dpt/pt2 and good pattern recognition

(e.g. efficiency for K0, L, and new long-lived particles)

3. Moderate B field (~3T)

VTX: fine pixel-CCD

HCAL(Pb(Fe)/scinti or digital)

W/Scinti ECAL

TPC

Si inner.-Trk

SC-coil

GLD Baseline Design (Aug’05 version)

3 T magnetic field

General Advantages of Larger DetectorGood Jet Energy (Particle) Flow Measurement

Better cluster separation Good charged track separation in a jet at the inner surface of the

calorimeter large BL2

Pattern recognition is easier Large n (sample)

Larger efficiency for Ks and Λ (any long lived) Good momentum resolution for charged particles

Large BL2 √ ｎ Good dE/dx measurement for charged particles

Large ｎSmaller relative volume of the dead space

Small ΔV/V

Disadvantage:Larger solenoid, then lower magnetic field, hence larger Si-VTX inner radius (beam bkg).Calorimeter volume increases (~L2) --> cheaper CAL scheme.

A view on PFA Fine segmentation of CAL (intrinsic) limits from Moliere length High B field spread hits, but not so much effective for dense jets Large ECAL radius Large Detector

Often quoted “Figure of Merit”:

22

2

MR

BR

: CAL granularityRM: Effective Moliere length

W/Scinti RM ~ 18mmPb/Scinti RM ~ 25mm

a few cm x a few cm segmentation is enough (?)

Baseline detector design

Some of sub-detectors (forward Si disks, for example) have not been seriously studied yet

Solenoid Iron Yoke

H-Cal

EM Cal

Main Tracker

Muon Tracker

VTX + SIT

Contact persons: H.B. park, H. Yamamoto (Asia) M. Ronan, G. Wilson (America)R. Settles, M. Thomson (Europe)

http://ilcphys.kek.jp/gld/index.html

Executuve board members

S. Yamashita - Detector optimizationA. Miyamoto - Simulation/ReconstructionY. Sugimoto - VertexingH.J. Kim - Silicon TrackerR. Settles - TPC trackerT. Takeshita - CalorimetersT. Tauchi - MDIM. Thomson - Space/Bandwidth

http://ilcphys.kek.jp/gld/documents/glddoc/homepage

Brief document

regular TV-meeting (weekly or bi-weekly)

GLD Concept Study

The LDC Model

The Large Detector Concept is based on a large continuous gaseous tracker surrounded by a highly granular calorimeter. The TESLA detector

concept, developedfor the TESLA TDRin 2001, is takenas the starting pointfor further optimization.

Similar to the AmericanLD concept.

Quadrant view

Quadrant view – vertex and forward tracking

• 5 layers of vertex pixel detectors (VTX)• 7 Si disks in the forward direction (FTD)• 2 layers of Si strip detectors outside the VTX detector (SIT)

• 5 layers of vertex pixel detectors (VTX)• 7 Si disks in the forward direction (FTD)• 2 layers of Si strip detectors outside the VTX detector (SIT)

Forward calorimetry