Belle upgrade tracking and vertexing
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Belle upgrade: Tracking and Vertexing. T.Kawasaki(Niigata-U). Introduction. High luminosity B factory High precision measurement with high statistics to search the new physics in B decays Many modes which are sensitive to new physics need High Hermeticity

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Belle upgrade tracking and vertexing

Belle upgrade:Tracking and Vertexing

T.Kawasaki(Niigata-U)

BNM2008 Atami, Japan


Introduction

Introduction

  • High luminosity B factory

    • High precision measurement with high statistics to search the new physics in B decays

  • Many modes which are sensitive to new physics need

    • High Hermeticity

    • Good efficiency on Low momentum & Ks daughter tracking,

(tCPV)

Ks vertexing

(tCPV)

Hermeticity

BNM2008 Atami, Japan


Requirements for sbelle tracker

Requirements for sBelle Tracker

  • Robust against high beam background

    • We assume ×20 BG @2×1035

      • Occ ~8% @the first layer of Belle SVD(r=2cm)

      • Fine segmentation

      • Fast pulse shaping & time slice information

    • High trigger rate

      • Need high speed & deadtime free readout

  • More tracking efficiency

    • Hermeticity

    • Shallow angle tracking. Low momentum tracking

    • Ks reconstruction

  • Better Resolution (At least competitive performance as current SVD)

    • Thin sensor (⇒refer the next talk for material effect)

    • Small BP radius

Belle SVD

Hit finding eff. vs. Occ.

15%

Occupancy

By Fujiyama(TIT)

BNM2008 Atami, Japan


Super belle detector loi 04

CsI(Tl) 16X0

g pure CsI (endcap)

Super Belle detector (LoI ‘04)

m / KL detection

14/15 lyr. RPC+Fe

g tile scintillator

Tracking + dE/dx

small cell + He/C2H6

  • remove inner lyrs.

    use fast gas

Si vtx. det.

4 lyr. DSSD

g 2 pixel/striplet lyrs. + 4 lyr. DSSD

SC solenoid

1.5T

Aerogel Cherenkov counter

+ TOF counter

g “TOP” + RICH

New readout and computing systems

BNM2008 Atami, Japan


Super belle vertex tracker loi 04

Super Belle Vertex Tracker(LoI ‘04)

Two thin pixel layer

Aim 1cm radius beam pipe

(cm)

r =150mm

17°

6 sensor layers to make

low momentum tracking

(cm)

Slanted layer to keep acceptance,

optimize incident angle and save detector size

BNM2008 Atami, Japan


Upgrade schedule

Upgrade Schedule

Along to the current upgrade schedule

Stop Belle

2007 2008 2009 2010 2011 2012

Stop Belle on the end of 2008 (JPY)

Start sBelle operation from the beginning of 2012

R&D

KEKB&Belle upgrade

Start sBelle

Reconstruction of detector takes 3 years

⇒We have only 1 year for R&D work!!

We need REALISTIC upgrade plan for T=0 operation in 2012 ( with ~1035 )

Further upgrade can be done after getting higher luminosity

(1cm beampipe, Thin Monolithic Pixel sensor …… needs further R&D work)

BNM2008 Atami, Japan


Central drift chamber

Central Drift Chamber

  • Large cover area in radius

    • 88~863 mm ⇒ 172~1118 mm

      • Inner part replaced by Si Tracker

    • 50 ⇒ 58 layers

  • Small cell to reduce occupancy

    • ⇒ 2.5mm

    • 8k ⇒15k sense wires

  • Same gas mixture :He + C2H6

  • Fast FADC readout

CDC

  • Occupancy esitimation

    • Hit rate : ~100kHz  ~5kHz(current) x 20

    • Maximum drift time : 80-300nsec  Shorter than the current one

    • Occupancy : 1-3% 100kHz X 80-300nsec = 0.01-0.03

  • Momentum resolution(SVD+CDC)

    • sPt/Pt = (0.11~0.19)Pt  0.30/b[%] :possible thanks to large cover in radius

BNM2008 Atami, Japan


Silicon vertex tracker

Silicon Vertex Tracker

  • Occupancy estimation

    • Assuming Occ ∝ Tp, channel area, 1/r2

    • Current SVD VA1(Tp=800ns): ~8%@ 1st layer

      L =2×1035 ⇒ 8% × 20BG = 160%!

  • Ex)APV25 (developed for CMS Si Tracker)

    • Tp=50ns ⇒ Factor 16 reduction is possible

  • ・160 pipeline FIFO

  • ⇒ pulse shape scan with 40MHz Clk

    • Further BG reduction is possible

    • by Pulse shape and timing information

  • 32 step FIFO as event queues

    • Deadtime free readout@ 10kHz trigger rate

Shaper

0

100

200

ns

  • ⇒ Standard rectangle DSSD is OK

BNM2008 Atami, Japan


Svt upgrade strategy

SVT upgrade Strategy

  • T=0 option (2012) for L= ~1035

    • Keep beampipe radius of 1.5cm same as current one

    • Current SVD configuration + 2 outer layers = 6layers

      • Improve Ks efficiency. Replace CDC inner layers

      • Similar design DSSD can be used

    • Fast Shaping(~50ns) + Timeslice on FE chip

  • Further upgrade for L >1035

    • Smaller beampipe radius (r =1cm or less)

    • Innermost (thin) Pixel layers

      • Improve impact parameter resolution

BNM2008 Atami, Japan


Study on detector configuration

CDC

CDC

SVD

SVD

Study on Detector configuration

SVD

L1-L4 @ r = 2.0, 4.35, 7.0, 8.8 cm

CDC

r= 8.8 ~ 86.3cm

SVD

Add L5&L6 @ r = (13), 14cm

CDC

r=16.0 ~ 112.0cm

sBelle

Belle

Put 5&6 layer

Evaluate new detector configuration

with TRACKERR calculation & GEANT3 full simulation

Modify the current Belle simulator

Use L4 ladder structure as L5&6 layer

No sensor at forward region

BNM2008 Atami, Japan


Impact parameter resolution

Impact Parameter resolution

Calculated by TRACKERR

r-fdirection

z direction

[cm]

[cm]

0.02

0.03

LoI ‘04

sBelle

SVD2(now)

For p-

0.2GeV

0.5GeV

1.0GeV

2.0GeV

0.01

0

1.4

sinq

Beampipe radius is important

Competitive performance as the current SVD

Occupancy effects.

Degradation of intrinsic resolution

is included.

Efficiency loss is NOT included

BNM2008 Atami, Japan


Momentum resolution

Momentum resolution

Calculated by TRACKERR

[rad]

fresolution

k resolution

[/MeV]

0.02

0.3

LoI ‘04

sBelle

SVD2(now)

For p-

0.2GeV

0.5GeV

1.0GeV

2.0GeV

0.01

0.1

0

1.4

sinq

Competitive performance as the current SVD

More layer doesn’t worsen momentum resolution

Refer the next talk

about a material effect

BNM2008 Atami, Japan


Ks reconstruction 5 th layer position

Ks reconstruction : 5th layer position

GEANT3

Full simulation

by Shinomiya

(Osaka)

Eff. Ks

Ks Vtx resolution

Require SVD hits

on 2 layers

Move 5th layer to outer

More Ks but poor B vtx resolution

=0.68

B vertex:

Ks pseudo track

+ Beam profile

Ks

e-

e+

Beam profile

Relative luminosity to measure Acp

BNM2008 Atami, Japan


Requirement on s n ratio

Requirement on S/N ratio

・Assuming [email protected] Si

・Noise determined by

Sensor Leakage current

Detector Capacitance

3DSSDs are readouted via FLEX

⇒Chain readout makes

large detector capacitance

Noise performance depends on FE chip

sBelle

Belle

VA1 @ Tp = 1ms

enc [e-]=180+ 7.5/Cd[pF]

⇒ Leakage current dominates

APV25 @ Tp = 50ns

enc [e-]= 246 + 36/Cd[pF]

⇒Detector capacitance is crucial

3DSSDs:~60pF630e-  ⇒ 2500e-

(calculate Cd component only)

BNM2008 Atami, Japan


Effect of poor s n ratio on the outer layers

Effect of poor S/N ratio on the outer layers

M.E. (Matching Efficiency)

= Prob.(SVD hits are found on at least 2 SVD layers)

GEANT3

Full sim.

Increase noise

CDC

M.E.

M.E.

SVT

Only 5&6 Layers

All Layers

Kalman filtering

Extrapolate track from CDC

10

×Typ.

10

×Typ.

Noise

Noise

S/N degradation on the outer layer doesn’t affect to M.E. so much

But, In case of Ks daughter track…

BNM2008 Atami, Japan


Matching efficiency for ks

Matching efficiency for Ks

1.0

normal

Matching efficiency

Noise x 2

Noise x 4

0

0 10 20 [cm]

Increase Noise on L5&L6 only

GEANT3

Full sim

By Nakagawa

(Niigata)

SVD Matched track

L3

L4

L5

L3

L4

L5

normal

Noise x 4

0 10 20 [cm]

r of Ks decay vertex

r of Ks decay vertex

M.E. for Ks daughters are affected by S/N degradation

Lose 20% (SVT) events with 4 times worse S/N

BNM2008 Atami, Japan


Bg effect on physics analysis

BG effect on physics analysis

Total performance of CDC + SVD

  • Major loss comes from low tracking efficiency for slow particles

  • Efficiency loss on high multiplicity event is serious

    • Moreover a pulse shape information CDC by FADC readout can save efficiency

    • Gain by SVD standalone tracker is not included

Preliminary

By Ozaki

BNM2008 Atami, Japan


Key technology for upgrade

Key technology for upgrade

  • Timeslice Information/Full Pipeline readout

    • Pipeline in FE chip(APV25, VA-modified, own ASIC)

  • Practical implementation scheme in a limited space

    • Ladder assembling. Mechanical Support structure

    • Cooling/Cabling scheme

  • Save S/N for outer layer.

    • FLEX readout. Chip on sensor

    • Sensor development

      • Low noise & Large area sensor is desirable

      • Thin (less material)  Thick (more signal)

  • Pixel sensor (Option for future upgrade)

    • Thin & Fast readout. Monolithic device?

  • No more HPK DSSD.

  • Micron? SINTEF?

  • New activities in India, Korea

BNM2008 Atami, Japan


Status of r d activity

Status of R&D Activity

Hybrid card with 4 APV25 chips

Operated with 40MHz clock (Princeton)

FADC: 40MHz digitization

Online sparsification with FPGA

  • We have been working to prepare Pipeline readout sensor module

(Vienna)

Beamtest done in KEK in Nov 2007

in KEK Fuji testbeam line 3GeV electron

Confirm the capability of

online sparsification algorithm

The result will come soon

BNM2008 Atami, Japan


Chip on sensor with flex hybrid

Chip on sensor with FLEX hybrid

Proposal by Vienna group

Readout each DSSD

by putting thinned FE chip on sensor

Cooling with water

through carbon fiber tube

(low material and good thermal

conduction)

No Cooling Cooling with 13℃ water

BNM2008 Atami, Japan


Schedule for cdc svt upgrade

Schedule for CDC/SVT upgrade

Start sBelle

Stop Belle

2007 2008 2009 2010 2011 2012

Test

Design

CDC

End Plate

Machining

R&D

Wire stringing

Cabling/Tubing

Installation

&Final Test

Cosmic Test

Sensor Production

Test

SVT

Design

R&D

Endring

&Beampipe

Assembling

Installation

Final Test

NOT official one

BNM2008 Atami, Japan


Summary

Summary

  • We have started activity for the practical detector design for Belle upgrade

    • CDC

      • Same gas mixture as Belle

      • Better resolution with larger coverage in radius

      • Reduce BG Occ. with small cell and time digitization

    • SVT

      • R=1.5cm Beampipe + 6 DSSD layers

      • Employ Standard DSSD with short shaping (=50ns) for T=0

      • Competitive resolution as the current SVD

      • R&D of Pixel sensor should continue for the further upgrade

  • Please join!! Any contributions are welcome!

BNM2008 Atami, Japan


Pixel sensor r d

Pixel sensor R&D

SOIPIX

KEK-OKI

Items to be achieved for High luminosity B factory

  • Readout Speed

  • Radiation Hardness

  • Thin Detector

  • Full-sized detector

2005

2.5mmx2.5mm

32x32 cells chip

・MAPS is the unique solution.

・Development of MAPS (Monolithic Active Pixel sensor)

is in world wide competition (ex:CAPS(Hawaii), SOIPIX (KEK))

・It looks promising but needs more R&D for a few years

Progresses in the coming a few years are very important.

2006

5mmx5mm

128x128 cells chip

BNM2008 Atami, Japan


Belle upgrade tracking and vertexing

Backups

BNM2008 Atami, Japan


Bkg trg rate in future

Bkg & TRG rate in future

x20 Bkg

x10 Bkg

KEKB

Bkg

SVD

CDC

PID / ECL

KLM

Synchrotron radiation

Beam-gas scattering (inc. intra-beam scattering)

Radiative Bhabha

BNM2008 Atami, Japan


Belle upgrade tracking and vertexing

BNM2008 Atami, Japan


Hit rate

Hit rate

Apr.-5th ,2005

IHER = 1.24A

ILER = 1.7A

Lpeak = 1.5x1034cm-2sec-1

ICDC = 1mA

Small cell

Inner

Main

10KHz

BNM2008 Atami, Japan


Simulation study for higher beam background

Simulation Study for Higher Beam Background

by K.Senyo.

MC +BGx1

MC+BGx20

BNM2008 Atami, Japan


Hit rate at layer 35

Hit rate at layer 35

Dec.,2003

LER

HER

IHER = 4.1A Hit rate = 13kHz

ILER = 9.4A Hit rate = 70kHz

Dec., 2003 : ~5kHz

Now : ~4kHz

In total 83kHz

BNM2008 Atami, Japan


Cdc main parameters

CDC : Main parameters

BNM2008 Atami, Japan


Intrinsic resolution vs occupancy

Intrinsic Resolution vs. Occupancy

Intrinsic Resolution

occupancy < 0.04

occupancy  0.3

residual

residual

At high occupancy,

g cluster shape is 'distorted'

g reconstructed cluster energy to be off

g the residual distribution to be widened

S.Fratina

g Occupancy

BNM2008 Atami, Japan


Hit efficiency vs occupancy

Hit Efficiency vs. Occupancy

Efficiency

Layer No.

hit or not?

1

2

Layer2

Layer1

  • Higher Occupancy

  • ~ Lower Hit Efficiency

  • Signal + background hits

  • g wider 'distorted' cluster

  • Wrongly associated background cluster

1.0

h

0.6

Layer4

Layer3

3

4

0% g 30%

Occupancy

BNM2008 Atami, Japan

Y.Fujiyama


Occupancy problem at innermost layer

Occupancy problem at innermost layer

L=1035/cm2/s

SVD2(800nsec)

  • Estimate occupancy at Super B

    • Occupancy at SVD2

      • At most, 10% in r =20mm for 1034/cm2/s

    • AssumingOcc. = luminosity/r2

      • r =15mm for 1035/cm2/s

        a occupancy = 200%

        Factor 40 of reduction is needed!!

  • How can we reduce Occ.?

    • Assuming Occ.

      = sensitive area* shaping time

    • Short shaping time

      • Tp=100ns is possible (Factor 8)

        (SVD2:VA1TA, Tp=800ns)

    • Strip area should be small.

      • Area=pitch*length a short strip

      • How to shorten a strip length by 1/5?

5%

BNM2008 Atami, Japan


Striplet design

Striplet design

SVD2(800nsec)

S-VTX(100nsec)

  • To shorten strip length, we propose new type of DSSD

    • Arrange strips in 45 degrees. Strip length is shortened

    • Small triangle dead region exists.

      • About 7 % in Layer1

    • Striplet can survive up to 2×1035/cm2/s

      (1036 needs pixel type sensor!)

Tp=50ns

5%

Striplet

Z

Dead region

U

10mm

14mm

V

70mm

BNM2008 Atami, Japan


Prototype striplet sensor hpk

Prototype Striplet Sensor (HPK)

74.1mm

  • Thickness:300mm

  • Double sided

    • P and N strips on N-bulk

    • Incline strip by 45 degree.

    • 1024 strips on each side

  • Strip pitch = 51mm in U-V direction.

    (Pad spacing is 72mm along sensor edge)

  • Since sensor size is small, inactive region can’t be ignored

  • How to reduce dead region

  • Check behavior near inactive region carefully.

71.0 mm

2.75mm

8.5mm

10.5mm

BNM2008 Atami, Japan


Scan strips with ir laser

Scan strips with IR laser

scan

  • Results

    • Striplet detector is functional.

    • No signal on the triangle part

      • The edge of active region is so sharp.

End of active region

N-side

P-side

sum

Signal (normalized)

Signal (normalized)

sum

Laser position[mm]

Laser position[mm]

BNM2008 Atami, Japan


Belle upgrade tracking and vertexing

全層のS/Nを悪くしたとき

Matching efficiency Normal S/N

Noise x 4

Noise x 5

BNM2008 Atami, Japan


Ks vertex

Ks vertexの分布

BNM2008 Atami, Japan


Belle upgrade tracking and vertexing

KsイベントでのMatching efficiency の変化

normal

Noise x 2

Noise x 4

r of Ks vertex

BNM2008 Atami, Japan


Belle upgrade tracking and vertexing

normal

Noise x 2

Noise x 4

Noise x 10

BNM2008 Atami, Japan


Mis alignment effect

Mis-alignment effect

Red: Perfectly aligned

Blue: 10um, 0.1mrad

Green: 20um, 0.2mrad

Pink: 30um, 0.3mrad

  • Large VTX tracker makes difficulty on alignment.

Ks VTX

Resolution

Ks eff.

Mis-alignment doesn’t affect to efficiency

BNM2008 Atami, Japan


Flex hybrid chip on sensor

FLEX hybrid/Chip on sensor

Flex

Hybrid

Connector

APV25

M.Pernicka, M.Friedl, C.Irmler (HEPHY Vienna)

BNM2008 Atami, Japan


Sensor configuration svd1 svd2

Sensor Configuration (SVD1→SVD2)

45cm

22cm

46cm

Z view

BNM2008 Atami, Japan


Svd2 ladder structure

Rib

Bridge

Hybrid

DSSD

FLEX

SVD2: Ladder Structure

  • VA1TA chip

    • 4 VA1TAs on a hybrid

    • 4analog signals read out in parallel

    • 128 channels/chip

    • 4 mW/channel

Number of channel:

128ch × 4 chips

×2 hybrid(f/z)×2 hybrids(F/B)

×(6+12+18+18) Ladders

= 110,592Analog signals

BNM2008 Atami, Japan


Readout with apv25 asic

Readout with APV25 ASIC

Trigger

  • Noise= (246 + 36/pF) @50nsec

Analog output

192 stageAnalog Pipeline (4 µsec)

128 channel

Multiplexer (3 µsec)

Shaper

preamp

Inverter

  • APV25 is chosen

    • Originally developed for CMS Silicon tracker

  • Operated with 40MHz clock

    • 192 stage pipeline (~4 µsec trigger latency)

    • Up to 32 readout queues

    • 128 ch analog multiplexing (3 [email protected] MHz)

    • Dead time: negligible at expected trigger rate of 10 kHz

BNM2008 Atami, Japan

45

The silicon tracker development at KEK, Toru TSuboyama (KEK), 19 Dec. 2007 SILC meeting at Torino, Italy


Hit timing reconstruction

Hit timing reconstruction

Trigger

Shaper

(HEPHY Vienna)

  • B-Factory --> 2 nsec bunch crossing

    • APV25 deconvolution filter can not be used.

  • Hit time reconstruction

    • Proposed by Vienna group

    • Read out 3, 6 … slices in the pipeline for one trigger.

    • Extract the hit timing information from wave form.

  • Proven in beam tests: Resolution ~ 2 nsec.

  • Reconstruction done in the FPGA chips in FADC board.

BNM2008 Atami, Japan

46

The silicon tracker development at KEK, Toru TSuboyama (KEK), 19 Dec. 2007 SILC meeting at Torino, Italy


Occupancy estimation

Occupancy estimation

Assuming [email protected]^35 , [email protected]^36

  • Int res= x1.5(1.2) for 30%(10%) occupancy

  • Occupancy ∝ 1/r2 × sensor aread

  • Hit efficiency loss is not considered. (-10% for 30% Occ)

Assuming factor 3 for safety margin, in order to calculate helix resolution.

BNM2008 Atami, Japan


Dr resolution

dr resolution

dr resolutoin

SuperB

SVD3mod

SVD3

For p

0.2GeV

0.5GeV

1.0GeV

2.0GeV

dr

New CDC conf.

TRACKERR V2.18

BNM2008 Atami, Japan


Dz resolution

dz resolution

dz resolutoin

SuperB

SVD3mod

SVD3

For p

0.2GeV

0.5GeV

1.0GeV

2.0GeV

dz

BNM2008 Atami, Japan


F resolution

f resolution

phi resolutoin

SuperB

SVD3mod

SVD3

For p

0.2GeV

0.5GeV

1.0GeV

2.0GeV

f

BNM2008 Atami, Japan


Tan l resolution

tanl resolution

tanl resolutoin

SuperB

SVD3mod

SVD3

For p

0.2GeV

0.5GeV

1.0GeV

2.0GeV

tanl

BNM2008 Atami, Japan


K resolution

k resolution

kappa resolutoin

SuperB

SVD3mod

SVD3

For

0.2GeV

0.5GeV

1.0GeV

2.0GeV

k

BNM2008 Atami, Japan


Belle upgrade tracking and vertexing

BNM2008 Atami, Japan


Belle upgrade tracking and vertexing

BNM2008 Atami, Japan


Belle upgrade tracking and vertexing

BNM2008 Atami, Japan


Belle upgrade tracking and vertexing

BNM2008 Atami, Japan


Belle upgrade tracking and vertexing

BNM2008 Atami, Japan


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