Super Belle CDC

1
Super Belle CDC
Shoji Uno (KEK) Dec-12th, 2008

• Basic design
• Electronics
• Test of pre-amplifier chips
• Wire stringing method
• Schedule

2
Baseline Design
sBelle
Belle
3
Main parameters
Present Future
Radius of inner boundary (mm) 77 160
Radius of outer boundary (mm) 880 1140
Radius of inner most sense wire (mm) 88 172
Radius of outer most sense wire (mm) 863 1120
Number of layers 50 58
Number of total sense wires 8400 15104
Effective radius of dE/dx measurement (mm) 752 978
Gas He-C2H6 He-C2H6
Diameter of sense wire (mm) 30 30
4
Wire Configuration
Present CDC
250 mm
1200 mm
New CDC
250 mm
5
Yesterday CDC meeting

• One and half hours from 1600
• 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.

6
Prototype of readout board by Y. Igarashi

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

Under 20cm
RJ45
ASB Discriminator
SFP Optical Transceiver
FADC
ASB Discriminator
FPGA (CONTROL, TDC)
ASB Discriminator
FADC
FPGA (SiTCP)
ASB Discriminator
RJ45
7
Test of Amplifier by N. Taniguchi

• Three amplifiers
• Hybrid pre-amplifier (with receiver, gain10)
  used in Belle-CDC
• ASD ( Amp Shaper Discriminator ) chip (with
  receiver, gain7 ) 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 90CH4 10)
Fe55 5.9keV X-ray
Amp
Receiver
Tungsten wire
Small tube chamber
8
Comparison
HV1.7kV
300mV
Belle AMP
? Belle AMP ATLAS ASD ? T-ASD
Pulse height mV
220mV
ATLAS ASD
140mV
HV kV
T-ASD
9
Comparison
Noise level
5mV
3mV
5mV
T-ASD
ATLAS ASD
Belle AMP
T-ASD
Saturation
ATLAS ASD
10
Results on test of amplifiers

• New ASIC chip is usable after some modifications.
• We can contact KEK electronics group closely.

11
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.

12
Discussion with technical stuffs

• We just started discussion with KEK technical
  stuffs.
• Calculation of deformation and stress
• Support method
• etc
• Need more man power.

13
My Personal Plan for Construction
14
Backup Slides
15
Hit rate
Apr.-5th ,2005 IHER 1.24A ILER 1.7A Lpeak
1.5x1034cm-2sec-1 ICDC 1mA
Small cell
Inner
Main
20
200kHz
10kHz
16
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
17
Simulation Study for Higher Beam Background
by K.Senyo.
MC BGx1
MCBGx20
18
BG effect on analysis
Talk by T. Kawasaki
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 With 40 shorter shaping With 40 shorter shaping
20 BG 51.4 -9.5
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 With 40 shorter shaping With 40 shorter shaping
20 BG 3.86 -40.5
By H.Ozaki
Preliminary

• 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).

Jan24-26, 2008
BNM2008 Atami, Japan
18
19
Background effect on tracking
H. Ozaki BNM2008
Many low momentum tracks, the hardest case for
tracking
Gain in reconstruction efficiency of BgDD
Tracker BKG Belle Software update SVD tracker
Belle e4.3 0 (definition) e7.1 65 e11.9 177
5 BG e6.3 47 e11.2 160
20 BG e3.8 12 e8.8 105
Excellent with help of SVD
19
20
Idea for upgrade

• In order to reduce occupancy,
• Smaller cell size
• A new small cell drift chamber was constructed
  and installed.
• It has been working, well.
• Faster drift velocity
• One 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.

21
Small Cell Drift Chamber
22
Photo of small cell chamber
Installation in 2003 summer
Just after wire stringing
23
XT Curve Max. Drift Time
Small cell(5.4mm)

• Normal cell(17.3mm)

24
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.

25
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.

26
Wire configuration 2

• 9 super-layers 5 axial 4 stereo(2U2V)
• A 1608, U 1606, A 1926, V 2246,
• A 2566, U 2886, A 3206, V 3526, A 3888
• Number of layers 58
• Number of total sense wires 15104
• Number of total wires 60000

27
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 CDC
• 12.6 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.

28
Expected performance

• Occupancy
• Hit rate 100kHz ? 5Hz X 20
• Maximum drift time 80-300nsec
• Occupancy 1-3 ? 100kHz X 80-300nsec
  0.01-0.03
• Momemtum resolution(SVDCDC)
• sPt/Pt 0.19Pt ? 0.30/b Conservative
• sPt/Pt 0.11Pt ? 0.30/b Possible ?
  0.19(863/1118)2
• Energy loss measurement
• 6.9 Conservative
• 6.4 Possible ? 6.9(752/869)1/2

29
About readout electronics

• At present,
• S/QT multi-hit TDC
• S/QT Q to Time conversion
• FASTBUS TDC was replaced with pipeline COPPER
  TDC.
• Three options,
• High speed FADC(gt200MHz)
• Pipeline TDC Slow FADC(20MHz)
• ASD chip TMC(or new TDC using FPGA) slow
  FADC near detector.
• ASIC group of KEK Detector Technology Project is
  developing new ASD chip.
• New TDC using FPGA is one candidate for TDC near
  detector.

30
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.

31
Radiation Damage Test
Gain degradation
Total accumulated charge on sense wire(C/cm)
a 93 Plastic tube d 94 SUS
tube b 93 Plastic tube O2 filter e 94
SUS tube O2 filter c 94 Plastic tube
f 94 Plastic tube
32
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 p2 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.

33
xt curve for new gas(7mm cell)
Drift time (msec)
Distance from wire (cm)
34
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.

35
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-CF4 is worse than Ar-based
  gas(P-10).

36
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.

37
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.

38
Luminosity Dependences
Feb, 2004
CDC BG did not change!
Inner most
Middle
Outer
39
Occupancy
Random trigger
Luminosity 1034cm-2sec-1 No. of channel NTotal Readout time (msec) Qgt0 Qgt50 NHit
Belle 1.5 8464 6 - 300
Babar 0.8 7104 2 700 350
Occ. NHit/NTotal () Occ./Time (/msec) Max. drift time (msec) 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
40
at HL6 in KEK
41
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
42
Weight

• Endplate
• Al, Thickness 10mm (12mm)
• 110kgx2 220kg (264kg)
• Outer Cylinder
• CRRP, Thickness 5mm
• 210kg
• Electronics Board
• G10, 48ch/board
• 0.3kgx315 95kg

43
Present support
44
Calculation of deformation and etc

• Deformation of Aluminum endplate
• Thickness of endplate 10mm ? 12mm
• Deformation ?1/t3 1 ?
  0.58
• Tension of field wire 120g ? 80g
• Gravitational sag, Sense 120mm(80g),
  Field300mm(80g)
• Total tension 4.8ton
• Stress calculation
• Thickness of outer cylinder CFRPmm
• Transition structure between endplate and outer
  cylinder
• Support structure
• Structure for wiring jig
• Simpler one as compared with Belle-CDC
• Etc.

45
Installation

• Removing and installation can be done using
  similar small bar in horizontal direction.

Cathode installation in vertical direction
CDC installation in horizontal direction
46
Signal Shape

• Each signal shapes are not same.
• Rise time 10sec
• Pulse width 200nsec.
• Maximum drift time 300nsec

47
Timing resolution

• Good timing resolution for the drift time
  measurement is key item.
• 250MHz sampling is not good enough.
• Present leading edge measurement shows 130mm
  resolution.
• 1nsec resolution is required.

FADC test
48
Sampling rate for energy loss measurement

• Slow sampling rate is good enough for energy loss
  measurement.
• 20MHz is OK.

49
Purposes of the Readout board Prototype

• A study of the CDC readout scheme
• Charge measurements by FADC
• Drift 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.

50
ASB part diagram

• ASB
• Amp. Shaper Buffer
• 4ch/chip
• Gain
• -360mV/pC -1400mV/pC
• (4 step variable)
• Power consumption 18mA

51
LOGIC part diagram
CLK For GFP
LVDS 2 pairs
RocketIO GFP
SFP (Optical connector)
CONTROL 3x4
16
ASB Discriminator
TDC (with FIFO)
TIMING LVDS 4x4 pairs
LVDS 2 pairs
SFP (Optical connector)
RocketIO GFP
LVDS 8 pairs
FADC Ti ADS5287
RJ-45
LVDS 4 pairs
FIFO
5
16
De-serializer
Spertan3A SiTCP
CLK 50MHz
ASB Discriminator
RJ-45
15
100base PHY
LVDS CLKs
48
8
TEST PIN
CONTROL
32
DIP-SW
ASB Discriminator
LVDS 8 pairs
FADC Ti ADS5287
PUSH SW
Vertex-5 LXT (XC5VLX50T, IO360pin)
3
5
LEMO
LEMO
4
LVDS CLKs
LED
ASB Discriminator
LEMO
8
DIP-SW
LEMO
16
TEST PIN
CLK 125MHz
Sampling CLK 2040 MHz
CLK 42.33MHz
8
DAC (Vth)
52
Schedule plan
2008/11 Specification design
2008/11,12 design 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 pattern M.Ikeno-san etc
2009/3 Start the practical study
53
Introduction

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

Fe55
ASD buffer

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

Fe55
54
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

55
ATLAS ASD
HV1.6kV
HV1.7kV
80mV
220mV
40ns
HV1.8kV
500mV
56
T-ASD
HV1.6kV
HV1.7kV
50mV
140mV
HV1.8kV
HV1.9kV
300mV
600mV
saturate
57
Belle AMP (HV1.8kV)
58
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