Overview of LC Detectors Mark Oreglia, University of Chicago

6 Jan 2005 Mark Oreglia, SLAC MDI Workshop 1

Overview of LC DetectorsMark Oreglia, University of Chicago

Outline:• Physics drivers

• The TESLA-NAlarge design

• The Silicon Detector concept• The Global Large Detector•Thanks to: Bambade, Barklow, Behnke, Brau, Breidenbach, Damerell, Miller, Ronan, Schumacher, Sugimoto, Torrence, Woods, …


3 Archetype Physics Topics

• Light Higgs -- tracker– Best recoil mass resolution in Z-> dileptons

• Strong EWSB -- calorimeter– Important to look at WW scattering– W/Z jet separation crucial

• Some SUSY scenarios -- hermeticity– Cosmology “benchmarks” summarized: – “bulk” -> annihilation -> smuon/selectron– “coannihilation” -> sau annihil. -> staus– Low angle backgrounds


Momentum Resolution

• e+e-ZHllX• Golden physics

channel!

• (1/p) = 7 x 10-5/GeV

• 1/10 LEP !!!

• goal: M<0.1x • dominated by

beamstrahlung


Impact Parameter• d= 5 m 10/p(GeV) m • 1/3 SLD !!! • excellent flavor tagging capabilities for charm and

bottom quarks– Need exceptional tagging for reducing combinatorial

background in multi-jets ... – Charge assignment– Asymmetry measurements– (measurement of Higgs BRs not so sensitive!)

• The big question: inner VTX radius– No simple answer – physics reach gains with lever arm and

background suppresion, esp low momentum particles– … thus, low MS, small radius is essential– Needs more validation, but we are talking 1.5 cm radius!– Instrument lifetime issue

• Here we need you to tell us what is possible


(Jet) Energy Resolution

• E/E = 0.3/E(GeV)

• <1/2 LEP !!!

• MDijet ~ Z/W

• separation between e+e-WWqqqq and e+e-

ZZqqqq


Particle Flow

• reconstruction of multijet final states

• e+e- H+H- tbtb bqqb bqqb

• Emphasis on combined systems now

• System compataibility means fine granularity in calorimeters (1 cm2 !!!)

• Digital mode possible, if backgrounds controllable


Hermeticity

• hermetic down to = 5 mrad

• Important physics with missing energy topologies (SUSY , extra-dim, Higgs, ...)

• Background issues– Ability to veto low-pT particles

– Crossing angle optimization

• Excellent physics motivation: SUSY-stau– DeRoeck’s talk here– Bambade & Lohman in Forward Region session


IR-Related Issues

• Good measurements in the low-angle region– Need to make pT cuts for physics analyses– Need to mask and reduce occupancies in low angle region– Need convincing? See Bambade’s summary of X-angle mtg

• Beam-beam interaction• broadening of energy distribution

(beamstrahlung)• ~5% of power at 500 GeV• backgrounds• e+e- pairs• radiative Bhabhas• low energy tail of disrupted beam• neutron “back-shine” from dump• hadrons from gamma-gamma


Time Structure:

Event rates: Luminosity: 3.4x1034 cm-2 s-1 (6000xLEP)e+e-qq,WW,tt,HX 0.1 / train e+e-X:~200 /Train

Background from Beamstrahlung: 6x1010/BX 140000 e+e-/BX + secondary particles (n,)

950 µs 199 ms 950 µs

2820 bunches

5 Bunch Trains/s tbunch=337ns

But still: 600 hits/BX in Vtx detector 6 tracks/BX in TPC

E=12GeV/BX in calorimeters E 20TeV/BX in forward cals.

Large B field and shielding

High granularity of detectors and fast readout for stable pattern recognition and event reconstruction


IR Issues

Hits/bunch train/mm2 in VXD,and photons/train in TPC

pairs


Beam Energy

• need to know <E>lumi-weighted

• Some analyses require better than 0.1%Some analyses require better than 0.1%• techniques for determining the lumi-weighted

<ECM>:energy spectrometers Bhabha acolinearity

• Other possibilities :Z, ZZ and WW events; use existing Z and W

massutilize Bhabha energies in addition to Bhabha

acol-pair events; use measured muon momentum

• 200 ppm feasible; 50 ppm a difficult 200 ppm feasible; 50 ppm a difficult challengechallenge

Top-mass: need knowledge of E-spread FWHM to level of ~0.1%


Crossing Angle


Summary of MDI Issues

• Detector designers need input from MDI experts:– Minimum VTX radius (smaller than you’d like!)– Masking optimization and best model (MC tool) for backgrounds– Feasibility of crossing angle options

• Detector designers need MDI experts to appreciate:– Need for small on systematic <E>lumi

– Need for reduction in low-angle background– Need for diagnostic instrumentation

• This talk continues with a description of current designs– New tools are causing all to be rethought– I’ve completely neglected the special requirements of a

detector optimized for or e- collisions• Even worse low-angle background problems


There are currently 3 Detector Concepts

• The WorldWide Study is working on a plan:– organization of effort– benchmarking performance– cdr/tdr’s– selection

• 3 concepts are materializing:– The TESLA concept: TPC-tracker – Silicon tracker + calorimetry (SiD)– new large magnetic volume concept (Global

Large Detector, GLD)

• Rethinking as new information available


Comparison of 3 Concepts(thanks to Y. Sugimoto)

•Very large R•Jet chamber or TPC•Scintilator/W-Pb-Fe

•Moderate R•TPC tracker•SiW ECAL

•Si tracking and ECAL•Small R•Smallest granularity


TESLA (and NA Large Det)(Thanks to Ties Behnke, Mike Ronan, Markus Schumacher)


Basic TESLA Detector Concept

No hardware trigger, dead time free continous readout for complete bunch train (1ms)

Zero suppression, hit recognition and digitisation in FE electronics

Large gaseous central tracking device (TPC)

High granularity calorimeters

High precision microvertex detector

All inside magnetic field of 4 Tesla


Overview of tracking system

Central region:Pixel vertex detector (VTX)Silicon strip detector (SIT)Time projection chamber (TPC)

Forward region: Silicon disks (FTD) Forward tracking chambers (FCH)(e.g. straw tubes, silicon strips)

• B=4T, RTPC=1.7m: momentum resolution (1/p) < 7 x 10-5 /GeV

• American version has larger TPC outer radius (2m), lower B (3T)

• looking at various TPC pad designs and readout


Vertex Detector: Conceptual Design

5 Layer Silicon pixel detector

•Small R1: 15 mm (1/2 SLD)

•Pixel Size:20x20m2 Point =3 m

•Layer Thickness: <0.1%X0 suppression of conversions – ID of decay electrons minimize multiple scattering

800 million readout cells

Hit density: 0.03 /mm2 /BX at R=15mm pixel sensors

Read out at both ladder ends in layer 1: frequency 50 MHz, 2500 pixel rows complete readout in: 50s ~ 150BX

<1% occupancy no problem for track reconstruction expected

Impact parameterd ~R1 point


Flavour Tagging

•LEP-c

Powerful flavour tagging techniques (from SLD and LEP)

M

e.g. vertex mass

charm-ID: improvement by factor 3 w.r.t SLD

Expected resolution in r,and r,z

~ 4.2 4.0/pT(GeV) m


Gaseous or Silicon Central Tracking?gaseous silicone e H0A 0 b b b b

advantages of gaseous tracking: many pointssimple pattern recognitionredundancy

“but be careful with these comparisons!”This is something of an aesthetic argument


Forward Tracking

FTD: 7 Disks 3 layers of Si-pixels 50x300m2

4 layers of Si-strips r= 90m

FCH: 4 LayersStrawtubes or Silicon strips (double sided)

250 GeV


Particle / Energy Flow60 % charged particles:30 % :10 %KL,nThe energy in a jet is:

Reconstruct 4-vectors of individual particles avoiding double counting

Charged particles in tracking chambersPhotons in the ECALNeutral hadrons in the HCAL (and possibly ECAL)

need to separate energy deposits from different particles

• small X0 and RMoliere : compact showers

• high lateral granularity D ~ O(RMoliere)

• large inner radius L and strong magnetic field

granularity more important than energy resolution

KL,n

e Discrimination between EM and hadronic showers

• small X0/had • longitudinal segmentation


Calorimeter Conceptual Design

ECAL and HCAL inside coil

large inner radius L= 170 cm good effective granularity

x~BL2/(RM D) 1/p

x distance between charged and neutral particle at ECAL entrance

•ECAL: SiW, •40 layers/24Xo/0.9lhad, 1cm2 lateral segmetation • E/E = 0.11/E(GeV) 0.01

•HCAL: many options• scintilator tiles, analog or digital• steel-scintillator sandwich


Forward Calorimeters

LCAL: Beam diagnostics and fast luminosity (28 to 5 mrad) ~104 e+e— pairs/BX 20 TeV/BX 2MGy/yr Need radiation hard technology: SiW, Diamond/W Calorimeter or Scintillator Crystals

LAT: Luminosity measurement from Bhabhas (83 to 27 mrad) SiW Sampling Calorimeter

aim for L/L ~ 10-4 require = 1.4 rad

TDR version of mask L* = 3 m

Tasks:

Shielding against background

Hermeticity / veto


SiD Design Starting Point(Thanks to Marty Breidenbach, John Jaros)

B = 5T Recal = 1.25m Zecal = 1.74m


The SiD Rationale

Premises:particle flow calorimetry will deliver the best possible performance

Si/W is the right technology for the ECAL

Excellent physics performance, constrained costs

Si/W calorimetry for excellent jet resolution

therefore…

• Limit Si/W calorimeter radius and length, to constrain cost

• Boost the B field to recover BR2 for particle flow, improve momentum resolution for tracker, reduce backgrounds for VXD

• Use Si microstrips for precise tracking


Cost (and physics) balance R and BHigh Field Solenoid and Si/W Ecal are major cost drivers.

Magnet Costs Stored Energy (SiD ~1.1GJ 80-100 M$) Cost [M$]

Fix BR2=7.8, tradeoff B and R

Stored Energy [GJ]

Delta M$ vs B, BR2=7.8 [Tm2]

Cost Partial, Fixed BR^2

0

10

20

30

40

50

60

70

0 1 2 3 4 5 6

B

Del

ta M

$

1.25

1.35

1.45

1.55

1.65

1.75

1.85

Linear

Power

Radius

0.00

50.00

100.00

150.00

200.00

250.00

0 0.5 1 1.5 2 2.5 3 3.5 4

Linear

Power

Exp Data


ECAL


Si Detector/ Readout Chip

Readout ~1k pixels/detectorwith bump-bonded ASIC

Power cycling – only passive cooling required

Dynamic range OK(0.1 - 2500 mip)

Pulse Height and Bunch Label buffered 4 deep to accommodate pulse train


HCAL

• Inside the coil• Rin= 1.42m; Rout= 2.44m• 4 Fe (or W, more compact)

2cm Fe, 1cm gap• Highly segmented

1x1 cm2 – 3x3 cm2 ~ 40 samples in depth

• Technology?RPCScint TileGEM

S. Magill (ANL)…many critical questions for the SiD Design Study: thickness? Segmentation? Material? Technology?


Silicon TrackingWhy silicon microstrips? SiD starting point

Robust against beam halo

Thin, even for forward tracks. Won’t degrade ECAL

Stable alignment and calibration. Excellent momentum resolution

p/p2~2 x 10-5


VXD Tesla SiD

Shorten barrel, add endcaps. Shorten Barrel CCDs to 12.5 cm (vs. 25.0cm)

add 300 m Si self-supporting disk endcapssupporting disk endcaps (multiple CCDs per disk) (multiple CCDs per disk)

This extends 5 layer tracking over max , improves forward pattern recognition.improve Coverage, improve impact param

5 CCD layers .97 (vs. .90 TDR VXD) 4 CCD layers .98 (vs. .93 TDR VXD)Readout speed and EMI are big questions.

-0.2

-0.15

-0.1

-0.05

0

0.05

0.1

0.15

0.2

0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4


SiD SubsystemsSo far, we’ve concentrated on calorimetry, tracking, and

magnet, since they define SiD architecture.Other subsystems need development & integration.• Flux Return/Muons/Had Tail Catcher

B field homogeneity for forward ecal?Longitudinal segmentation?Technology?

• Very Forward TrackingPixels or strips?

• Very Forward Cal (huge and active area!)Active masks and vetoesLumcalBeamcal (pair monitor)


Global Large Detector(Thanks to Y. Sugimoto)


Basic design concept

Detector optimized for Particle Flow Algorithm (PFA)

• Large/Huge detector concept

– GLC detector as a starting point– Move inner surface of ECAL outwards to optimize for PFA

– Larger tracker to improve pt/pt2

– Re-consider the optimum sub-detector technologies based on the recent progresses

• Different approaches

– B Rin2 : SiD

– B Rin2 : TESLA

– B Rin2 : Large/Huge Detector


Optimization for PFA

• Jet energy resolution– jet

2 = ch2 + 2 + nh

2 + confusion2 + threashold

2 　

– Perfect particle separation:

• Charged-/nh separation– Confusion of /nh shower with charged particles is the

source of confusion Separation between charged particle and /nh shower is important

– Charged particles should be spread out by B field– Lateral size of EM shower of should be as small as

possible ( ~ Rmeffective: effective Moliere length)

– Tracking capability for shower particles in HCAL is a very attractive option Digital HCAL

EEjet /%15~/


Merits and demerits of Large/Huge detector

• Merits– Advantage for PFA– Better pt and dE/dx resolution for the main tracker– Higher efficiency for long lived neutral particles (Ks, , and

unknown new particles)• Demerits

– Cost ? – but it can be recovered by• Lower B field of 3T (Less stored energy)• Inexpensive option for ECAL (e.g. scintillator)

– Vertex resolution for low momentum particles• Lower B requires larger Rmin of VTX because of beam

background (IP)~5 10/(psin3/2) m is still achievable using wafers of

~50m thick


Forward Detector components

• Si forward disks / Forward Calorimeter– Tracking down to cos=0.99– Luminosity measurement

• Beam calorimeter– Not considered in GLC detector – At ILC, background is 1/200. Need serious consideration– Careful design needed not to make back-splash to VTX– Minimum veto angle ~5mrad (?) Physics

• Si pair monitor– Measure beam profile from r-phi distribution of

pair-background– Radiation-hard Si detector (Si 3D-pixel)


Parameters comparedSiD TESLA GLD

Solenoid B(T) 5 4 3

Rin(m) 2.48 3.0 3.75

L(m) 5.8 9.2 9.86

Estored(GJ) 1.4 2.3 1.8

Main Tracker

Rmin (m) 0.2 0.36 0.4

Rmax(m) 1.25 1.62 2.0

BL2.5 5.7 7.1 9.7

m 7 150 150

Nsample 5 200 220

pt/pt2 3.6e-5 1.5e-4 1.2 e-4


Paramters (cont’d)SiD TESLA GLD

ECAL Rin (m) 1.27 1.68 2.1

BRin2 8.1 11.3 13.2

Type W/Si W/Si (W/Sci)

Rmeff (mm) 18 24.4 16.2

BRin2/Rm

eff 448 462 817

Z (m) 1.72 2.83 2.8

BZ2/Rmeff 822 1311 1452

X0 21 24 27

E+HCAL

5.5 5.2 6.0

t (m) 1.18 1.3 1.4

Overview of LC Detectors Mark Oreglia, University of Chicago

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