Super Belle CDC Basic design Electronics  Test of pre-amplifier chips Wire stringing method Schedule Shoji Uno (KEK) Dec-12 th, 2008

Baseline Design Belle sBelle

Main parameters Present Future Radius of inner boundary (mm) Radius of outer boundary (mm) Radius of inner most sense wire (mm) Radius of outer most sense wire (mm) Number of layers 5058 Number of total sense wires Effective radius of dE/dx measurement (mm) Gas He-C 2 H 6 Diameter of sense wire (  m) 30

1200 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 signals SFP for Belle DAQ data line LEMO input x 3 LEMO output x1 Shielded substrate FPGA (CONTROL, TDC) RJ45 SFP Optical Transceiver 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%+CH 4 10%) Tungsten wire Fe keV X-ray Small tube chamber Amp Receiver

Comparison HV=1.7kV ~220mV ~140mV T-ASD ATLAS ASD 40ns HV [kV] Pulse height [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-ASD ATLAS 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.-5 th,2005 I HER = 1.24A I LER = 1.7A L peak = 1.5x10 34 cm -2 sec -1 I CDC = 1mA Main Inner Small cell 200kHz ×20

Hit rate at layer 35 I HER = 4.1A Hit rate = 13kHz I LER = 9.4A Hit rate = 70kHz Dec., 2003 : ~5kHz Now : ~4kHz Dec.,2003 In total 83kHz HER LER

Simulation Study for Higher Beam Background by K.Senyo. MC +BGx1MC+BGx20

Jan24-26, 2008BNM2008 Atami, Japan18 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 Nominal56.8 %0.0 % ×5 BG56.0 %-1.5 % ×20 BG49.0 %-13.8 % With 40% shorter shaping ×20 BG51.4 %-9.5 % B Eff Ratio-1 Nominal % ×5 BG % ×20 BG % With 40% shorter shaping ×20 BG % By H.Ozaki Preliminary Talk by T. Kawasaki

Background effect on tracking 19 Many low momentum tracks, the hardest case for tracking Gain in reconstruction efficiency of B  D * D * H. Ozaki BNM2008 Excellent with help of SVD

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% CH 4  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 : 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 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.

Expected performance Occupancy  Hit rate : ~100kHz  ~5Hz X 20  Maximum drift time : nsec  Occupancy : 1-3%  100kHz X nsec = 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% : Conservative  6.4% : Possible  6.9*(752/869) 1/2

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(>200MHz)  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.

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 tube b: ’93 Plastic tube + O2 filter e: ’94 SUS tube + O 2 filter c: ’94 Plastic tube f: ’94 Plastic tube Total accumulated charge on sense wire(C/cm) Gain degradation

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 CH 4 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 CH 4 100nsec Distance from wire (cm) Drift time (  sec) He/C 2 H 6 = 50/50 100nsec

Drift Velocity Two candidate gases were tested.  CH 4 and He-CF 4 In case of He-CF 4, higher electric field is necessary to get fast drift velocity. In case of CH 4, 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 90 Sr were measured for various gases. The resolutions for CH 4 and He(50%)- C 2 H 6 (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  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 cm -2 sec -1 No. of channel N Total Readout time (  sec) Q>0Q>50 N Hit Belle Babar ~700 ~350 Occ. = N Hit /N Total (%) Occ./Time (%/  sec) Max. drift time (  sec) Occ./Time x Max. Drift time (%) Normalized by Lum.(%) Belle Babar ~ 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) 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 endplate  Thickness of endplate 10mm  12mm Deformation  1/t 3 1  0.58  Tension of field wire 120g  80g Gravitational sag, Sense : 120  m(80g), Field:300  m(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 130  m resolution.  1nsec resolution is required. FADC test

Sampling rate for energy loss measurement Slow sampling rate is good enough for energy loss measurement. 20MHz is OK. Sampling width (nsec) dE/dx Resolution measurement (%)

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.

ASB part diagram ASB  Amp. Shaper Buffer  4ch/chip  Gain : -360mV/pC ~ -1400mV/pC (4 step variable)  Power consumption : ~18mA

LOGIC part diagram FADC Ti ADS5287 ASB Discriminator SFP (Optical connector) RJ-45 LVDS 8 pairs CONTROL 3x4 Vertex-5 LXT (XC5VLX50T, IO:360pin) LVDS 2 pairs LVDS 4 pairs RJ TIMING LVDS 4x4 pairs LEMO RocketIO GFP 100base PHY Spertan3A SiTCP TDC (with FIFO) 3 FIFO 4 LED DIP-SW 8 16 TEST PIN 16 CONTROL CLK 125MHz Sampling CLK 20~40 MHz CLK 42.33MHz ASB Discriminator FADC Ti ADS5287 ASB Discriminator ASB Discriminator De-serializer 5 LVDS 8 pairs 5 48 DIP-SW TEST PIN 8 32 CLK 50MHz LVDS CLKs LVDS CLKs PUSH SW DAC (Vth) 8 RocketIO GFP SFP (Optical connector) LVDS 2 pairs CLK For GFP

Schedule plan 2008/11Specification design 2008/11,12 design and drawing the circuit  ASD part (T.Taniguchi-san)  Digital part (M.Saito-san) 2008/12 endorder the substrate 2009/2 Check the mask pattern  M.Ikeno-san etc … 2009/3Start the practical study

Introduction ATLAS-ASD  Pre gain 0.8 V/pC, main x 7 Fe 55 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=1.6kVHV=1.7kV HV=1.8kV ~80mV 40ns ~220mV ~500mV HV=1.9kV ~600mV distorted

T-ASD HV=1.6kVHV=1.7kV HV=1.8kVHV=1.9kV ~50mV ~140mV ~300mV~600mV 40ns saturate

Belle AMP (HV=1.8kV)