R&D program in JFY2002 for R&D program in JFY2002 for JLC vertex detectorJLC vertex detector

N.Tamura ; Niigata University

Y.Sugimoto, A.Miyamoto ; KEK

T. Aso ; Toyama National College of Maritime Technology

K.Abe ; Tohoku Gakuin Univ.

G.Iwai, K.Fujiwara, H.Takayama ; Niigata University

ContentsContentsI) Design concepts and Requirements

– Accelerator Design– VTX detector design– IR design and backgrounds

II) Present results and Activities– Radiation hardness– Spatial resolution– Fast readout electronics

Summary

AcceleratorAccelerator 　　 DesignDesign

6mrad crab crossing

Beam time Structure

Bunch-train Structure

Train = One pulse192 bunches

1.4ns N~1E+10 particles

1/150Hz=6.7ms

Beam profile at IP

243nm

3.0nm dz=110um

I )

VTX DesignVTX Design VTX

– Precise Secondary vertex reconstruction Reconstruct decay vertices of B and D meson decays with excellent b/c

jet separation

– Improvement of momentum resolution Requirements

– Unambiguous 2D reconstruction at high hit density Pixel devices

Expected occupancy in a 20m x 5cm strip detector ～ 100% ! , for hit background rate of about 1hit/mm2/train.

– Less materials 　 (Especially for low momentum tracks) Thin devices Operation at room temperature ~ 0 C -> Simple structure/Easy operation

-> Less thermal distortion of wafers

o

Room temperature operationRoom temperature operation CCDs

– Features Thin/Low-density material Low power consumption But Needs cooling ?

– w/o Cooling system Avoid multiple scattering by

cooling system Avoid thermal distortion of s

ensors ( fabrication – operation temperature discrepancy)

Desirable to operate in room temperature ~ 0 C )

Back-illumination CCD : HPK S7170

Thickness ~20m

CCD Flatness

o

VTX detector designVTX detector design

Baseline design – |cos | < 0.90– Pixel size 25 um– 1.25cm x 5cm x330um– 4Layers with 10deg tilt

( r=24,36,48,60 mm)( Ladder 16/24/32/40)(Sensor 2/3/4/5)

– Intrinsic resolution 4 m(Just for a Simulation input )

1.1824

60

IR Design and BackgroundIR Design and Background

Model d) 3T with SC-QC1

QC1 : Super Conducting magnet L* = 4.3 m To reduce back scattering background produced by the interaction at QC1

R=8~16.5cm

Background estimationBackground estimation Beam-Beam Interaction

– e+e- pair production– Beamstrahlung

Secondary produced backgrounds

R(mm)

TRC(X) 3T *

Preliminary

R(mm)

JLC-A **

JLC-Y**Model b)

VTX1 24 0.77 25 0.36 0.97VTX2 36 0.13VTX3 48 0.10 50 0.42 0.25VTX4 60 0.04 75 0.14 0.11

*Geant4 ( SR/PhotoNuclear )Include solenoid ( uniform 3T ) +QC1 ( Ideal gradient )

Electron backgrounds ( /mm2/train) **Geant3

95bunchesLow Lum.

Similar toTRC(X)

NLC - JLC

Neutrons Previous Study 1E+9/cm2/Yr (Beamstrahlung)

1Yr operation e+e- pair ~1hit/mm2/train1.5E+11/cm2/Yr

Present results and ActivitiesPresent results and ActivitiesRadiation hardnessSpatial resolutionFast readout electronics

II)

Radiation Radiation hardnesshardness

HPK10 HPK10

notch

EEV

Type S5466 CCD02-06

Pixel size [m] 24 22

R/O clock 2-phase 3-pahse

Epitaxial layer[m]

10 20

Notch none 3m none

MPP Operation

Inverted by holes

Si02 – Si Interface

Small packet

Notch CCD 2-Phase CCD 3-Phase CCD

Low density

CCD Structure CCD Structure [cont’d][cont’d]

Result > 1.5E+11e/cm2

JLC: 1.5E+11/cm2/yr @2.4cm

Result > 1.5E+10 n/cm2

JLC: 1E+9/cm2/Yr (Preliminary)

Radiation hardness

Vee (V) Vee (V)

Dark

curr

ent

(ele

ctro

ns/

pix

)

Electrons from 90Sr Neutrons from 252Cf

HPK10

Radiation hardness Radiation hardness [cont’d][cont’d]

Methods VCTI

improvement

3-phase to

2-phase

~2.5 times

Std to

notch structure

~3 or 4 times

CTI properties

3Phase 2Phase

Std

CTI

Notch

VC

TI (

Irr

ad

iati

on

)C

TI (

Irr

adia

tion)

Electron

Neutron

HPK10

CTI~Nt/Ns

Concentration Nt : Defect

Ns : Signal

Radiation test Radiation test -1--1- Our tests showed “Lifetime of CCD > 1Year !

Why additional test of radiation damage, then ?

Non

-Ion

izin

g E

ner g

y L

oss

Radiation damageis thought to be proportional to NIEL

The radiation damageat JLC estimated to be10 times bigger thanour study using 90Sr.

Radiation damage by high energy (>10MeV)electrons should be studied.

Radiation test -1- Radiation test -1- [cont’d][cont’d]

Non

-Ion

izin

g E

ner g

y L

os s

Radiation damage by high energy (>10MeV) electrons

should be studied.

Radiation test (First trial Radiation test (First trial 2002/12/9)2002/12/9)Experimental setup

ElectronBeam150 MeV

Pt 0.1X0

0.5X0

Bending Magnet

Choice of Settings1) Primary Beam Energy

150MeV electrons2) Target radiation length

0.1/0.5 X0

3) B field High/Low Tesla mode

Tohoku-Univ. Lab. of Nuclear Science

Radiation test Radiation test [cont’d][cont’d]

Plan “Trial Run” -> Real Run in May?, 2003

1. Study of Background @LNS CsI(pure) calorimeter2. Irradiation @LNS Energy of electrons On target ; 150 MeV On CCD ; 100 MeV Irradiation: 5x1010/cm2 Dosimetry; RadFET

Radiation test Radiation test [cont’d][cont’d]

Energy distribution of the scattered electrons

Incident electrons: 125 MeV/c

Radiation test Radiation test [cont’d][cont’d]

3. Cryogenic measuring system for CCD - almost same as the one which Stefanov-san used in Japan

Cryostat

Temperature Controller CCD Board inside the cryostat

Spatial resolutionSpatial resolution-Test beam--Test beam-

S/N > 10 @278K

Dark current is suppressed by the successfulOperation of Inverted mode. Noises in a pixel (R/O cycle ~ 3sec. )

HPK10(23e)/ HPK50(58e) / EEV(37e)

HPK50 : HPK with epitaxial layer of 50m

4-Layers CCD Tracker

Spatial resolutionSpatial resolutionTemp.( C)

Method HPK10 HPK50 EEV

-15 C AC 3.56+-0.02 2.67+-0.09 3.71+-0.08

RLM 2.76+-0.03 2.79+-0.09 2.94+-0.10

+5C AC 3.68+-0.03 3.34+-0.10 3.84+-0.08

RLM 3.46+-0.04 3.67+-0.12 2.59+-0.16

RLM : RLM functionAC : Analog centered

PmaxPR =

Pix

el

AP

ixe

l B

Sig

nal

of

Pix

el A

Sig

nal

of

Pix

el B

o

Spatial resolution Spatial resolution [cont’d][cont’d]

Intrinsic ResolutionIs better than 3 m.

Intrinsic ResolutionIs better than 3 m. Thermal diffusion of signal charge improves resolution.

Comparison with simulationComparison with simulation- by T. Aso- by T. Aso

En

ergy

dep

osit

(keV

)

Thickness of active layer(m)

Geant4:Energy Deposit　　　 2GeV,π‐HPK50 12.0keV 7×7clsHPK10

2.2keV　 2×2cls

Energy Deposit in Silicon

Estimated Active layer•11m for HPK10•51m for HPK50

Active Active LayerLayer

51.1m

11.0m

HPK10 HPK50

Charge sharing simulation - by T. AsoCharge sharing simulation - by T. Aso

＋： d/A=50%×： d/A=30%＊： d/A=20%△： d/A=10%□： d/A=5%

Depletion (d)Field Free (f)

Active Active (A=d+f)(A=d+f)

X X

Log(R) Log(R)

d ~ sqrt(2Dt)

f ~ G.R.HopkinsonNIM A216(1983)432 E

ner

gy(k

eV)

N×N　 Clustering

HPK50

HPK10

Open ： Exp

Close ： Sim

Drift coff. *Drift Time

Electronics fabricationElectronics fabrication Readout operation

– All pixels must be readout every train crossing interval of 6.7 ms, in the real experiment at JLC.

– 10MHz readout can transfer about 250x250pix in the interval.

5cm

1.25cm

250x250pix/chip16chips/sensor

Total 424 sensors

6784chips needed.

Fast R/O System -1-Fast R/O System -1-Features Fast Not expensive Low power Flexible design

Optical linkLVDS link

1st

2ndFinal

Fast R/O System -2-Fast R/O System -2-Evaluation board of ADC

– CCD Signal processor chip for Digital Camera 9x9mm2 chip size ~ $6/chip

– AD9844A(Analog Devices Co.) 12bit 20MSPS ADC 20MSPS Correlated Double Sampler

6bit variable CDS Gain Amp. Low power consumption(65mW/2.7V)

SHP SHP

SHD

FADC

Fast R/O System -3-Fast R/O System -3-

LVDS Inputs for clocks etc

XC2V404CS144C(FPGA)

AD9844A[FADC]

Backside Interface to Digital board (12 bit DBUS]

Linearity was confirmed.LSB resolution 0.2mV.

Dynamic range 0~800mV

SummarySummary Design and status of JLC VTX detector is presented. Goal --- CCD operation at room temperature

Radiation hardness : No problem, so far.– But, further investigation is necessary.

Electrons => Higher energy must be confirmed experimentally. ( Additional experiments are going. )Neutrons => Yield of neutron is ambiguous ( beam dump ) ( Reliable simulation with precise geometry, JUPITER)

Spatial resolution : < 3m at -15 C.– More investigation of charge sharing property improve resolution?

( Laser scanner test at Niigata Univ. with 2x2m spot.)

Readout Electronics: Evaluating– Study the effect of Fast readout for irradiated samples

Evaluation of thinned device– Partially thinned CCD ..(Distortion measurement system: ready)

o

CCM CCD (1)CCM CCD (1)CCM (Charge carrier multiplier)

– Multiply generated charge using Impact ionization

•Multiplying generated charge directly in the charge domain before conversion into a voltage•High-field region between the two neighboring gates•Gained energy is dissipated through Impact Ionization [II]•Small variance in the II

CCM CCD(2)CCM CCD(2)Difficult to reduce the noise floor of

existing charge detection amplifiers particularly at high clocking freq.

CCM CCD(3) –IMPACTRON-CCM CCD(3) –IMPACTRON- IMPACTRON

– Texas Instruments– TC253SPD– 658(H)x496(V)A

pix. In Image Sensing Area

– 7.4m Square Pixels

– Charge multiplication gain 1~30– Charge conversion

gain w/o CCM 10V/e– Epitaxtial Layer

depth?

690

496

4

500

CCM (400pix)

Charge Multiplication!!!

CCM CCD (4) –CCM CCD (4) –IMPACTRON-IMPACTRON-

Gamma ray spectrum55Fe0 oC

Driver for Impactron is now being developed. ↓

↓ Will be compared withHPK S5466