Super Belle CDC

Basic design Electronics

Test of pre-amplifier chips

Wire stringing method Schedule

Shoji Uno (KEK)　　　

Dec-12th, 2008

Baseline Design

Belle

sBelle

Main parameters

Present FutureRadius of inner boundary (mm) 77 160Radius of outer boundary (mm) 880 1140Radius of inner most sense wire (mm) 88 172Radius of outer most sense wire (mm) 863 1120Number of layers 50 58Number of total sense wires 8400 15104Effective radius of dE/dx measurement (mm) 752 978Gas He-C2H6 He-C2H6

Diameter of sense wire (m) 30 30

1200 mm

250

mm

250

mm

Present CDC

New CDC

Wire Configuration

Yesterday CDC meeting

One and half hours from 16:00 Main topics

Test results of pre-amplifier chips Wire stringing method

Several new people joined. One new KEK posdoc candidate 3 persons from KEK electronics group 5 foreigners One Japanese person (non current CDC member) 3 current CDC KEK members 13 in total : more than I expected.

We are waiting for more people.

Prototype of readout board by Y. Igarashi

Under 20cm

ASB +Discriminator

ASB +Discriminator

ASB +Discriminator

ASB +Discriminator

FADC

16ch/board BJT-ASB/Comparator part FADC: over 20MHz / 10bit FPGA : Vertex-5 LXT

TDC: 1 nsec counting FADC reading Control

FPGA: Spertan3A SiTCP

RJ-45 for SiTCP RJ-45 for Belle DAQ timing signal

s SFP for Belle DAQ data line LEMO input x 3 LEMO output x1 Shielded substrate

FPGA(CONTROL,

TDC)R

J45

RJ4

5

SF

PO

ptic

al T

rans

ceiv

er

FADC

FPGA(SiTCP)

Test of Amplifier by N. Taniguchi

Three amplifiers Hybrid pre-amplifier (with receiver, gain:10) used in Belle-CDC ASD ( Amp + Shaper + Discriminator ) chip (with receiver, gain:7 ) used in ATLAS-TSC

No production, now.

ASB ( Amp + Shaper + Buffer ) developed by ASIC group of KEK Can be optimized for Super Belle CDC in near future.

Check signal shape using oscilloscope

Gas (Ar 90%+CH4 10%)

Tungsten wire

Fe55 5.9keV X-ray

Small tube chamber

Amp Receiver

Comparison HV=1.7kV

~220mV

~140mV

T-ASD

ATLAS ASD

40ns

HV [kV]

Puls

e h

eig

ht

[mV

] ● 　 Belle AMP■ 　 ATLAS ASD▲ 　 T-ASD

100ns

40ns

Belle AMP

~300mV

~5mV

ATLAS ASD

Comparison

~5mV

Belle AMP

~3mV

T-ASD

HV=1.9kV

~600mV

distorted

HV=1.9kV

~600mV

saturate

T-ASDATLAS ASD

Noise level

Saturation

Results on test of amplifiers

New ASIC chip is usable after some modifications.

We can contact KEK electronics group closely.

Wire stringing

Now, I am thinking a vertical stringing, not horizontal. Once, I thought the horizontal stringing.

Vertical stringing with outer cylinder.Human can stand inside the chamber and can touch

the wire. Inner diameter without the small cell part : ~500mm Inner diameter of present transition cylinder : 580mm

Stringing with tension can be done from outer layer.Two-way method ( Belle-CDC ) is not necessary.

Discussion with technical stuffs

We just started discussion with KEK technical stuffs. Calculation of deformation and stress Support method etc

Need more man power.

My Personal Plan for Construction

Backup Slides

Hit rate

10kHz

Apr.-5th ,2005IHER = 1.24AILER = 1.7ALpeak = 1.5x1034cm-2sec-1

ICDC = 1mA

Main

Inner

Small cell

200kHz×20

Hit rate at layer 35 　410I**2 + 1400*I + 80

0

200

400

600

800

1000

1200

1400

1600

0 0.2 0.4 0.6 0.8 1

HER Beam Current(A)

Hit

rat

e(H

z)

740I**2 + 470*I + 80

0

500

1000

1500

2000

2500

3000

0 0.5 1 1.5 2

LER Beam Current(A)H

it R

ate

(Hz)

IHER = 4.1A Hit rate = 13kHzILER = 9.4A Hit rate = 70kHz

Dec., 2003 : ~5kHzNow : ~4kHz

Dec.,2003

In total 83kHz

HER LER

Simulation Study for Higher Beam Background

by K.Senyo.

MC +BGx1 MC+BGx20

Jan24-26, 2008 BNM2008 Atami, Japan 18

BG effect on analysis

Major loss come from low tracking efficiency on slow particles. Efficiency loss on high multiplicity event is serious. Pulse shape information by FADC readout can save efficiency. SVT standalone tracker will be a great help (not included in this study).

B Eff Ratio-1

Nominal 56.8 % 0.0 %

×5 BG 56.0 % -1.5 %

×20 BG 49.0 % -13.8 %

With 40% shorter shaping

×20 BG 51.4 % -9.5 %

)()( SK/J )( 3KD,DDDD s***

B Eff Ratio-1

Nominal 6.48 0.0 %

×5 BG 5.69 -12.2 %

×20 BG 2.28 -64.9 %

With 40% shorter shaping

×20 BG 3.86 -40.5 %

By H.Ozaki Preliminary

Talk by T. Kawasaki

Background effect on tracking

19

)( 3KD,DDDD s***

Many low momentum tracks, the hardest case for tracking

Gain in reconstruction efficiency of BD*D*

H. OzakiBNM2008

Excellent with help of SVDExcellent with help of SVD

Idea for upgrade In order to reduce occupancy,

Smaller cell sizeA new small cell drift chamber was constructed and installed. It has been working, well.

Faster drift velocityOne candidate : 100% CH4

Results show worse spatial resolution due to a large Lorentz angle.

A beam test was carried out under 1.5T magnetic field.So far, no other good candidate.

Small Cell Drift Chamber

Photo of small cell chamber

Installation in 2003 summerJust after wire stringing

XT Curve & Max. Drift Time

Small cell(5.4mm)Normal cell(17.3mm)

Chamber Radius

Inner radius Physics : Vertexing efficiency using Ks SVD determines the boundary. At present, the boundary is 15cm in radius.

Outer radius New barrel PID device determines the outer radius. At present, 115cm is selected, tentatively.

The boundary condition is important to start construction. Basically, CDC can manage any radius.

Wire configuration 1

Super-layer structure 6 layers for each super-layer

at least 5 layers are required for track reconstruction. Even number is preferred for preamp arrangement on

support board to shorten signal cable between feed-through and preamp.

Additional two layers in inner most super-layer and outer super-most layer. Higher hit rate in a few layers near wall. Inner most layer and outer most layer are consider as

active guard wire.

Wire configuration 2

9 super-layers : 5 axial + 4 stereo(2U+2V)A 160*8, U 160*6, A 192*6, V 224*6, A 256*6, U 288*6, A 320*6, V 352*6, A 388*8

Number of layers : 58 Number of total sense wires : 15104 Number of total wires : ~60000

Deformation of endplate

Number of wires increase by factor 2. Larger deformation of endplate is expected. It may cause troubles in a wire stringing process and other occasions.

Number of holes increases, but a chamber radius also enlarges. Cell size is changing as a function of radius to reduce number of wires. The fraction of holes respect to total area is not so different, as comparing

with the present CDC.11.7% for present CDC12.6% for Super-Belle CDC

In order to reduce deformation of endplates, The endplate with a different shape is considered. Wire tension of field wires will be reduced.

Anyway, we can arrange the wire configuration and can make a thin aluminum endplate.

Expected performance

OccupancyHit rate : ~100kHz ~5Hz X 20 Maximum drift time : 80-300nsec Occupancy : 1-3% 100kHz X 80-300nsec = 0.01-0.03

Momemtum resolution(SVD+CDC) Pt/Pt = 0.19Pt 0.30/[%] : Conservative Pt/Pt = 0.11Pt 0.30/[%] : Possible 0.19*(863/1118)2

Energy loss measurement 6.9% : Conservative6.4% : Possible 6.9*(752/869)1/2

About readout electronics

At present, S/QT + multi-hit TDCS/QT : Q to Time conversionFASTBUS TDC was replaced with pipeline COPPER TDC.

Three options, High speed FADC(>200MHz) Pipeline TDC + Slow FADC(~20MHz) ASD chip + TMC(or new TDC using FPGA) + slow FADC near det

ector. ASIC group of KEK Detector Technology Project is developing new AS

D chip. New TDC using FPGA is one candidate for TDC near detector.

Summary

When Belle group decides the upgrade plan, we can start construction of the new chamber soon. It takes three years to construct the chamber.

Outer radius( and inner radius) should be fixed as soon as possible.Barrel PID determines the schedule. Inner radius should be determined by SVD.Supporting structure should be discussed.

One big worry is man power. I hope many people join us when the upgrade plan starts.

Radiation Damage Test

a: ’93 Plastic tube d: ’94 SUS tubeb: ’93 Plastic tube + O2 filter e: ’94 SUS tube + O2 filterc: ’94 Plastic tube f: ’94 Plastic tube

Total accumulated charge on sense wire(C/cm)

Gai

n de

grad

atio

n

Test chamber and beam test

A test chamber with new cell structure was constructed.Part of inner most 20 layer( 8 layers with small cell + 12 layers with

normal cell)

A beam test was carried out in the beginning of June at 2 beam line of 12GeV PS.We confirmed the simulation for pure CH4 is correct. Velocity under

1.5T is not faster than the present gas and the drift line is largely distorted due to larger Lorentz angle.

Similar performance could be obtained using new S/QT module with less dead time.

Many data were taken using 500MHz FADC, which was developed by KEK electronics group. Now, a student is analyzing data. We hope to get information about minimum necessary sampling speed for timing and dE/dx measurement.

xt curve for new gas(7mm cell)

Distance from wire (cm)

Pure CH4

100nsec

Distance from wire (cm)

Dri

ft ti

me

(se

c)

Dri

ft ti

me

(se

c )

He/C2H6 = 50/50

100nsec

Drift Velocity

Two candidate gases were tested. CH4 and He-CF4

In case of He-CF4, higher electric field is necessary to get fast drift velocity.

In case of CH4, faster drift

velocity by factor two or more can be obtained, even in rather lower electric field.

dE/dx Resolution

The pulse heights for electron tracks from 90Sr were measured for various gases.

The resolutions for CH4

and He(50%)-C2H6(50%) are same.

The resolution for He-CF

4 is worse than Ar-based

gas(P-10).

Wire chamber

Wire chamber is a good device for the central tracker. Less material Good momentum resolution. Cheap It is easy to cover a large region. Established technology Relatively easier construction. Many layers Provide trigger signals and particle

ID information.

Wire chamber can survive at Super-KEKB. Our answer does not change after the last WS in

2004. The beam background became smaller even for higher beam

current and higher luminosity. We recognize the luminosity term is small, clearly.

CDC Total Current Maximum current is

still below 1.2mA, even for higher stored current and higher luminosity.

Vacuum condition is still improving. Thanks KEKB people for

hard work. I hope there is still room

to improve vacuum condition further.

Luminosity Dependences

CDC BG did not change!

Feb, 2004

Inner most

Middle

Outer

Occupancy

Luminosity

1034cm-2sec-1

No. of channel

NTotal

Readout time

(sec)

Q>0 Q>50

NHit

Belle 1.5 8464 6 - 300

Babar 0.8 7104 2 ~700 ~350

Occ. = NHit/NTotal

(%)

Occ./Time

(%/sec)

Max. drift time

(sec)

Occ./Time x Max. Drift time (%)

Normalized by Lum.(%)

Belle 3.5 0.58 0.4 0.23 0.15

Babar 4.9 2.45 ~0.6 1.47 1.84

x20 Bkgd in Belle CDC ~ x3 Bkgd in Babar DCH

Random trigger

at HL6 in KEK

Curved Endplate

Deformation of endplate due to wire tension was calculated at design stage of present Belle CDC (Total tension: 3.5 Ton).

Deformation(mm) 35.2 2.03 1.31

Present New

Weight

Endplate 　 Al, Thickness : 10mm (12mm) 110kgx2 = 220kg (264kg)

Outer Cylinder CRRP, Thickness : 5mm 210kg

Electronics Board G10, 48ch/board 0.3kgx315 = 95kg

Present support

Calculation of deformation and etc

Deformation of Aluminum endplateThickness of endplate 　 10mm 　　 12mm

Deformation 1/t3 1 0.58Tension of field wire 　 120g 80g

Gravitational sag, Sense : 120m(80g), Field:300m(80g)Total tension 4.8ton 　 　　　

Stress calculation Thickness of outer cylinder 　 CFRP ： mm 　Transition structure between endplate and outer cylinder

Support structure Structure for wiring jig

Simpler one as compared with Belle-CDC

Etc.

Installation Removing and installation

can be done using similar small bar in horizontal direction.

Cathode installation in vertical direction CDC installation in horizontal direction

Signal Shape

Each signal shapes are not same.

Rise time : ~10sec Pulse width : ~200nsec. Maximum drift time :

~300nsec

Timing resolution

Good timing resolution for the drift time measurement is key item.

250MHz sampling is not good enough.Present leading edge

measurement shows 130m resolution.

1nsec resolution is required.

0100200300

400500600700

0 10 20 30 40

Sampling width (nsec)

Spat

ial r

esol

utio

n (

m)

Before correction

After correction

FADC test

Sampling rate for energy loss measurement

Slow sampling rate is good enough for energy loss measurement.

20MHz is OK. ns0

2

4

6

8

10

12

0 100 200 300

1/ Tサンプリングレート（ ）

%分解

能（）

Sampling width (nsec)

dE/d

x R

esol

utio

n m

easu

rem

ent (

%)

Purposes of the Readout board Prototype

A study of the CDC readout schemeCharge measurements by FADCDrift time measurements by FPGA base TDC

A evaluation of ASB for CDC readout A study of the noise diffusion from the

readout board to CDC We hope to study about CDAQ/Front-end

data transport.

ASB part diagram

ASB Amp. Shaper Buffer 4ch/chip Gain :

-360mV/pC ~ -1400mV/pC (4 step variable)

Power consumption : ~18mA

LOGIC part diagram

FADCTi

ADS5287

ASBDiscriminator

SFP(Optical connector)

RJ-45

LVDS8 pairs

CONTROL 3x4

Vertex-5 LXT(XC5VLX50T, IO:360pin)

LVDS 2 pairs

LVDS 4 pairs

RJ-4515

TIMING LVDS 4x4 pairs

LEMO

LEMO

LEMO

LEMO

RocketIOGFP

100basePHY

Spertan3ASiTCP

TDC(with FIFO)

3

FIFO

4 LEDDIP-SW8

16

16

TEST PIN16

CONTROL

CLK125MHz

Sampling CLK20~40 MHz

CLK42.33MHz

ASBDiscriminator

FADCTi

ADS5287

ASBDiscriminator

ASBDiscriminator

De-

seria

lizer5

LVDS8 pairs

5

48

DIP-SW

TEST PIN8

32

CLK50MHz

LVDSCLKs

LVDSCLKs

PUSHSW

DAC(Vth)

8

RocketIOGFP

SFP(Optical connector)

LVDS 2 pairs

CLKFor GFP

Schedule plan

2008/11 Specification design

2008/11,12design and drawing the circuit

ASD part (T.Taniguchi-san)Digital part (M.Saito-san)

2008/12 end order the substrate

2009/2 Check the mask patternM.Ikeno-san etc…

2009/3 Start the practical study

Introduction

ATLAS-ASD Pre gain 0.8 V/pC , main x 7

Fe55

Fe55

T-ASD (Taniguchi-san, ASIC group) ~ 7V/pC

ASD buffer

Conclusion

Gain : T-ASD is smaller (0.6 x ATLAS ASD, half of Belle AMP)

Noise level: T-ASD is smaller Resolution : T-ASD seems to

be better than ATLAS ASD Rise time is ~ 20 ns for ATLAS

ASD and T-ASD Saturation : ~ 1.9kV

Beam test using test chamber and new ASIC chip ~ Apr, 2009

ATLAS ASD

HV=1.6kV HV=1.7kV

HV=1.8kV

~80mV

40ns

~220mV

~500mV

HV=1.9kV

~600mV

distorted

T-ASD

HV=1.6kV HV=1.7kV

HV=1.8kV HV=1.9kV

~50mV ~140mV

~300mV

~600mV

40ns

saturate

Belle AMP (HV=1.8kV)