The I nternational L inear C ollider program.

The International Linear Collider program.

Marcello PiccoloLNF-INFNFrontierScience, Milano Sept. 2005

M.Piccolo, Frontierscience, Milano

Sept. 2005

Agenda

• Brief historical excursus

• The Physics case

• The experimental challenges

• Detector design (s)

• Time scale

• Conclusions


Sept. 2005

The start of the O(1TeV) L.C.

• It is difficult to set a start date for a program that was in the back of at least 50% of particle physicists mind since at least 25 years.

• I will arbitrarily set the start date at the Saariselka ( Finland ) meeting in September 1991.

• It might be interesting to remember which kind of environment we were living in.


Sept. 2005

The lepton collider Physics at the end of 1991

• Going back to the summer of 1991 − 106 Z collected at LEP− The Standard Model was capable of

describing everything LEP would turn out.

− E.W. fits were almost perfect− The four LEP detectors were just

turning toward heavy quark Physics.− For the record E.W. fits were giving :

Mtop=120 ± 40 GeV/c2

− CDF had an upper limit on top mass at 91 GeV/c2


Sept. 2005

The men with vision• Maury Tigner

− The first one to think of it.• Nuovo Cimento 37 (1965) 1228

• Burt Richter− The first one to do it

• SPC SLC

• (Late) Bijorn Wiik− The superconducting RF advocate

• TESLA ILC• His legacy is embedded the actual

program


Sept. 2005

The study groups• Originally Europe, Japan and USA organized

their own study groups.

• After a while it was realized that a common framework was needed, and the LCWS was organized, with the aim of bringing together the regional groups to share experiences, results and …frustrations

• This in my opinion was the starting of the global character of the effort.

• Now here we are with a programs that carries the word International as a first name.


Sept. 2005

The Physics program : seeking answers the TeV

Scale

The TeV energy region hold the promise of giving back answers to our quests.

Origin of mass and electro-weak symmetry breaking

Why such a disparity between mweak and mPlanck

What is most of the matter in the Universe made of

and more…

The Tevatron is already at work to open a window into this regime.

LHC will allow a (quasi) complete view on phenomena at the TeV scale!


Sept. 2005

Will the LHC be enough ?• Although the LHC is the most powerful

research instrument ever built in our field, it does have limitations:

• LHC detectors record about 10-5 of the total cross section

• Analysis will be carried out on 10-10 of the total cross section.

• No events balance visible longitudinal momentum.

• Events with missing neutrals have unknown pt

• High-purity b tagging, any charm tagging and tagging is difficult

• Most LHC analyses rely on a model.

• They are powerful if the underlying assumptions are correct, not so powerful if wrong.


Sept. 2005

ILC Physics Case

Whatever LHC will find, one CANNOT give up the ILC, that warrants a Physics program which stands on his own feet.

1. If there is a ‘light’ Higgs (consistent with precision EW) proof that it is a particle responsible for giving masses (a)

2. If there is a ‘heavy’ Higgs (inconsistent with precision EW) verify the Higgs mechanism is at work as in (a) understand (in)consistencies with S.M.

3. 1./2. & new states (SUSY, XD, little H, Z’, …) A completely spectroscopy is available to be discovered and measured

4. No Higgs, no new states (inconsistent with precision EW) find out what is wrong with the S.M. look for threshold effects of strong EWSB

(TESLA TDR, Snowmass01, ACFA report, …)


Sept. 2005

ILC physics case

)( tan dardModelSnewPhysics XXXee

Produce new particles look at deviations

Find new type of states and measure it(cross sections, masses,

BR’s, Quantum numbers)

Look at known processes and find deviations from the expected, through virtual effects.

Needs good experimental work AND good knowledge of what to expect.

Peek deep intomulti-TeV region

ModeldardSee tan


Sept. 2005

Hadrons cry to loud (B. Toushek ca. 1960)

Electron positron collisions at high energy allow an almost complete

exploration of the phenomena deemed relevant to EWSB.

The initial state is made of individual constituents, and this provide some advantages with respect to protons.

• very well defined (and tunable) centre-of-mass energy

•….and all of it usable.

• clean, fully reconstructable events (no unknown pl )

• polarized beams.

• moderate backgrounds

• Unfortunately chronical lack of counting rate.

p pe+ e-


Sept. 2005

The ILC

• Center-of-Mass Energy ~ 90 – 1000 GeV

Time Structure : 5 (10?) Bunch-trains/s Time between collisions: ~ 300 (150) ns

950 µs 199 ms 950 µs

2820 bunches

• Baseline Luminosity :2x1034 cm-2s-1

(>1000xLEP

e+e-qq ~100/hr e+e-W+W- ~1000/hr e+e-tt ~50/hr e+e-HX ~10/hr

e+e-qq ~0.1 /Bunch Train e+e-X ~200 /Bunch Train ~500 hits/BX in Vertex det. ~5 tracks/BX in TPC

• `Backgrounds‘ (depends on ILC parameters)

ILC baseline parameters currently being discussed

e.g. TESLA TDR

Event rates modest – small compared to LHC


Sept. 2005

Configuration Parameter Space


Sept. 2005

Impact on Detector Design

Radiation hardness not a big concern. Time structure of the machine not demanding. Worst type of Physics background Angle crossing to be studied in detail.

Final focus lenses (L* ) have big effect on backgrounds

The detector design dictated by Physics

MDI + crossing-angle important : might place constraint on design


Sept. 2005

Physics processes

• To asses the capabilities of the ILC, I will go over few individual reactions:− Higgs Physics− Super symmetry studies− Gauge bosons− Top


Sept. 2005

Higgs Physics

• If can use Higgstrahlung, model

independent observation.

• mass measurements

• absolute branching ratios

• total width

• spin, CP

• top Yukawa coupling

• self coupling

Garcia-Abia et al


Sept. 2005

Higgs at LHC

• LHC will discover some Higgs, if it is there within three years (2011?)

• Will a discovery be enough ? I doubt it.

• Let us suppose to discover H , and to see, as a cross check a final state ttH.

• Technipion? Scalar or pseudo-scalar? Does it couple with W/Z?


Sept. 2005

Legitimate questions • Was the Higgs boson discovered ?

− Is it the particle responsible for mass ?− Does it have the correct spin parity

assignment 0+?− Is it really the condensate that fills the

Universe ?

• To prove that it is indeed what gives mass to particles− Spin/Parity− Couplings− Vacuum expectation value− Branching Ratios− Self coupling


Sept. 2005

Higgs Boson at LC• Angular distributions

in e+e–ZX depend on X=h, A, V

is it a 0+?


Sept. 2005

Higgs Boson at LC

• Branching Fractions prove couplings mass.

The Higgs is responsible for masses. (Battaglia)


Sept. 2005

Higgs Boson at LC

• Final state ZH

• ALR is proof that is produced by s-channel Z-exchange

• If Z gauge boson, H scalar boson only two vertices possible

• A VEV is needed to have a ZZH vertex.

• Measurement of gZ will prove that Z mass is (partly) due to the scalar.

H. Murayama LBL-38891


Sept. 2005

Precision Higgs physics

SM

2HDM/MSSM

Yamashita et alZivkovic et al


Sept. 2005

Now, we have the Higgs and we know is the one that generates masses……

• The S.M. assumes a negative Why ?

• Yes, there is a condensate that shields the weak force.

• Why do we have something that condenses ?

Why the condensation scale ~TeV<<MPl


Sept. 2005

Possible (model) solutions• Super symmetry

− Crisis with the electron self energy: ….introduction of antimatter

− Double # particles + boson to fermion and viceversa

• Cooper pair mechanism − Cooper pairs: two electrons bond together− Higgs as a fermion antifermion pair

Technicolor

• Physics ends @ TeV scale− Ultimate scale: quantum gravity− Gravitational effects @ ~TeV

hidden dimensions


Sept. 2005

If it is there LHC will discover super symmetry; however many hard questions will be still unanswered or partially answered:

• is it really SUSY? (measurement of quantum numbers)

• how is it realized? (MSSM, NMSSM, …)

• how is it broken?

ILC will be able to provide answers to these questions!

Make full use of the flexibilityof the machine:

- tunable energy

- polarized beams

- possibly e-e- and collisions

Supersymmetry

500200 1000 3000

Sobloher


Sept. 2005

Super symmetry at LC

• To prove : effective super-partners− Spins differ by 1/2− Same quantum

numbers SU(3)SU(2)U(1)

− Super symmetric couplings

Spin 0?


Sept. 2005

Supersymmetry at LC (cont.)

Two methods to obtain absolute sparticle masses:

in the continuum: at the kinematic threshold:

many more observables than just masses:

- angular distributions, FB-asymmetries- cross sections- LR-asymmetries- ratios of branching ratios

possibility to determine SUSY parameters without many model assumptions

FreitasMartyn


Sept. 2005

Supersymmetry LC + LHC

A LHC/LC joint effort:

errors of a 19-parameter fit using ILC+LHC:

allows for model-independent investigation of GUT/Planck scale features of the theory:

Bechtle et al

Porod et al

The overall results on SS data fitting:

It is clear that neither of the two

programs would have such an analyzing

Power.


Sept. 2005

DM/DM main sensitivity

bulk 3.5%

focus 1.9%

co-ann. 6.5%

funnel 3.1%

01 R R 1,e , ,

0 0 0 0 0 01 2 1 3 1 1 1 1 1, , , , ( )

0 01 1 1,

0 01 1A , ,

The Cosmic ConnectionSUSY provides excellent candidate for dark matter (LSP)

(Other models provide TeV-scale WIMPs too)

Sensitivity for DM search at accelerators of the same order

as astrophysics searches…. ALCPG study/prel.


Sept. 2005

And if no Higgs comes around ?

Cross section for weak vector boson scattering violates unitarity at ~1.2 TeV, and no new resonances appear

Birkedal et al.Krstonosic et al.

ILC sensitivity deep into multi-TeV region from VB final stateseff. Lagrangian parametersof strong EWSB:

Higgsless model: new resonancein WZWZ

Coupling structure from ILC if resonance seen by LHC


Sept. 2005

Top

Hoang et al

We know that is there.Threshold scan provides remarkable improvement on mass measurementTheory (NNLL) controls mt(MS) to 100 MeV

Heinemeyer et al

very precise mtop vital

- improved SM fits- MSSM (mh prediction)- DM-density in mSugra- …


Sept. 2005

Detector Design for the ILC

Optimize the detector so thatevery bit of luminosity counts

In e+e- colliders we always fight with

small cross sections.

Limit systematic errors

Requirements differentfrom LHC detectors

Overall detector concept

R&D on key components


Sept. 2005

A detector with Particle flow

To exploit to the fullest the ILC environment one seeks complete

reconstruction of complex final states (multi-jets, tau’s)

often accompanied by missing-E

How can we achieve the very best

energy resolution for jets ?

Generally accepted paradigm:

Particle flow

Particle flow is:

- a detector concept

- and an algorithm


Sept. 2005

The Particle Flow AlgorithmBasic idea: reconstruct every single particle in the event

for each particle type exploit the detector subsystem which cando that best!

~60% charged tracker

~30% photons (from 0) ECAL

~10% neut. hadrons HCAL

sounds reasonablechallenge: cluster mixing/double counting

Separate

charged from neutral: B field, R, trans. granularity, material

EM from HAD: trans. + long. granularity (“shower tracking”)

Goal : E/E = 30%/E0.5


Sept. 2005

The Particle Flow Algorithm (cont.)

HadHadmemepE EKEKpKjet

2...

2..

42

Resolution terms relevant: hadronicenergy and wrong clustering

Build the best hadronic calorimeterMinimize wrong clustering

Granularity


Sept. 2005

Detector concept studies

3 different incarnations of a PF detector studied

They have a lot in common:

- both ECAL+HCAL inside coil- highly-granular calorimeter- precision pixel vertex detector- common R&D on components!

concepts, but no closed ‘collaboration’

They differ in:

choice of tracking: TPC vs. Si

magnetic field 3 – 5 T

inner radius of ECAL

choice of ECAL readout Si vs Sc

www-sid.slac.stanford.edu

www.ilcldc.org

ilcphys.kek.jp/gld/

SiD

LDC

GLD


Sept. 2005

A different detector concept

• At the Snowmass meeting in August a new detector concept was presented:

• The main difference with respect to the traditional PFA detectors is that the calorimeter system on which is based can, by construction, separate e.m. energy, e.m. + hadronic energy and may be the binding energy of nuclear components …..


Sept. 2005

Dual-Readout Module (DREAM)

“Unit cell”


Sept. 2005

Design Issues and Detector R&D

Detector integral part of ILC Design – meet schedule of GDE

Concept optimisation & R&D to be carried out ….since yesterday!Key components:

1. Vertex Detector

2. Charged Particle Tracking

3. Calorimetry

4. Muon system

5. Trigger

6. Forward Region

7. Machine Detector Interface

https://wiki.lepp.cornell.edu/wws/

R&D review Panel established by world-wide LC study to promote and coordinate detector R&D for the ILC

Keeps tabs of R&D activities around the world at:


Sept. 2005

do

Vertex Detector ( the GLD preliminary optimization)

Want to prove gHff~mf

O(%) measurements of the branching ratios Hbb,cc,gg

Important for many physics analysese.g. couplings of a low mass Higgs

We like to be better than before

a: point resolution, b : multiple scattering

heavy flavour tagging is a tool of choice

d0 ~ a b/[p(GeV)sin3/2Goal: a=5m, b=10m


Sept. 2005

Inner radius: ~20 mm for impact parameter resolution the smaller the betterLayer Thickness: as thin as possible minimize conversions, reduce M.S.

Main design considerations:

Constraints: Inner radius constrained by e+e- pair depends on the f.f. details + B field Layer thickness depends on Si technology

T. Maruyama

B=5 T

In the end, design driven by machine + technology !

GLD Baseline design:Fine pixel CCDs (FPCCDs)Point resolution : 5 m Inner radius : 20 mmOuter radius : 50 mmPolar angle coverage : |cos|<0.9

BUT ultimate design depends on worldwide detector R&D

GLD Baseline


Sept. 2005

Backgrounds in GLD VTX

Assuming to be able to bear 0.5% occupancy, set the radius of the first layer accordingly How much of a disadvantage is B = 3T ?

3 T 4 T 5 T

GLD VTX Forced to a slightly larger inner radius : 2mm ? Will depend on ILC parameters/MDI !

This is a disadvantage of lower B-field in GLD concept How much does the larger inner radius matter ?

Sugimoto


Sept. 2005

T.KuhlRinner = 26mm Rinner = 15mm

Here charm-tagging efficiency for 70 % purity decreases from 45 % 30 % as Rinner increased from 15 mm 26 mm

NOTE: not completely fair comparison as different wafer thickness

Main impact – charm tagging, e.g.

3 Tesla field not helpful from point of view of charm-tagging BUT probably not a big concern

Tesla study


Sept. 2005

Vertex Detector

Many technologies under study – very active field

CCD DEPFET MAPSand many others…

750 x 400 pixels20 m pitch

CPR1 CPR1

1 MPixel

CCD with column par. r/o

DEPFET Mimosa 9 (MAPS)


Sept. 2005

Central Tracking

4 1t(1/ p ) 2.8 10 GeV

4 1t(1/ p ) 0.7 10 GeV

Driving Physics: Particle Flow: efficiency (kinks , high dE/dx), resolution less importantHiggs recoil mass, SUSY di-lepton endpoints: momentum resolution

Two options: Gaseous or Silicon tracker?

TPC:

>200 3D space pointswith ‘gas type’ point-res O(100µm)(LDC, GLD)

Si:

5 (pix) + 5 (strips)high-res pointspoint-res o(few µm)(SiD)


Sept. 2005

Use Micro Pattern Gas Detectors (GEMs, MicroMegas) for gas amplification

- native 2D structure- ion-feedback suppression built in

-- thin end-plates

R&D topics:

-stable operation on large scale- optimize resolution/pad geometry- operation in magnetic field- field cage design

TPC R&D

Significant effort worldwideLC-TPC collaboration


Sept. 2005

Central Tracking: Silicon Tracker

SiLC collaboration

R&D:

long ladders (Reduce M.S.)long shaping time: low noise

develop r/o chipspattern recognition use VTX as seed

FE prototype ASICmomentum resolution: simulation

GOAL: testbeam in 2006


Sept. 2005

Calorimetry

Driving physics: Jet energy resolution in multi-jet (6,8,..) events tau reconstruction non-pointing photons

E.G. : Strong EW symmetry breakingdistinguish W and Z in their hadronic

decays w/o kinematic constraints

E%30E%60

ALEPH like resolution ILC goal


Sept. 2005

The H self coupling


Sept. 2005

Calorimeter and Particle Flow algorithm are a real challenge

Present technologies under study:EM calorimeter: Si W (SiD,LDC), Sc W (GLD)HAD calorimeter: scintillating tiles (‘analog’) RPC, GEM, tiles (‘digital’)

addressed by a world-wide R&D efforte.g. CALICE: 26 Institutes, 9 Countriesin 3 Regions

ECAL1st testbeamat DESY

Calorimetry

2 electrons, ~3cm apart

Testbeam data!


Sept. 2005

HCALHCAL issues:

active medium gaseous or scintillator?

Understand hadron showers

Scintillator: new possibilities with

small photo-sensors (“SiPMs”)

Prototype construction under way

Scintillator plane with SiPM r/oMinical prototype at DESY

Detail of SiPM

Fluctuations of hadronic showersSimulation of same 6 GeV pion:


Sept. 2005

ECAL+HCAL joint testbeam

Tail Catcher

ECALECAL

HCALHCAL

Electronic Racks

Beam

1m3 prototype testbeam planned for 2006detailed understanding of el-mag and hadronic showers ina highly-granular Calorimeter


Sept. 2005

Radiator choice for Had.Cal.• Lately W was looked

at as a possible radiator for the Had-cal.

• Detailed evaluation ongoing.

• Material cost could be offset by smaller radius….

• S.C. Coil could cost much less.


Sept. 2005

Simulation of cal. overall performances

• Simulation results with the two had.cal. options for the LGD


Sept. 2005

Trigger and DAQ• The common wisdom is that there is

no need for triggering.

• The idea, as of now, is to use commercial hardware to pipeline the data during the beam crossing (~ 1 msec.) and build the event during the intra-beam time (~200 msec.)

• Individual detectors might tag “interesting bunch crossings”

• Really a no-bias trigger.


Sept. 2005

Program development

Aug. 2005 (Snowmass) - optimize detector parameters. Prepare inputs to machine.

End 2005 - A detector R&D document to go withthe machine baseline configuration document.

End 2006 - Detector Concept Report (one document with multiple concepts, costed) to go with the machine reference design report.

2008 Detector Concept will be part of: ILC Technical Design report

…let me now borrow GDE director transparencies from his Snowmass presentation:


Sept. 2005

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


Sept. 2005

GDE – Near Term Plan

• Schedule• Begin define Configuration (Snowmass Aug 05) • Baseline Configuration Document by end of 2005-----------------------------------------------------------------------• Put Baseline under Configuration Control (Jan 06) • Develop Reference Design Report by end of 2006

• 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


Sept. 2005

Conclusions

• ILC Physics program is compelling; it does stand on its own.

• LHC and ILC are two remarkable instruments that will help us make the big step forward in understanding our Universe.

•In my opinion, there will be a big positive interference between the LHC and ILC programs.

• Development of the detectors is considered an integral part

of the GDE.

• The schedule for the technical reports/designs is ambitious. 2008 is close: plenty of possibilities to come and contribute to the startup of this program.

The I nternational L inear C ollider program.

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