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Super Belle CDC

Super Belle CDC. Basic design Electronics Test of pre-amplifier chips Wire stringing method Schedule. Shoji Uno (KEK) Dec-12 th , 2008. Baseline Design. sBelle. Belle. Main parameters. Wire Configuration. Present CDC. 250 mm. 1200 mm. New CDC. 250 mm. Yesterday CDC meeting.

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Super Belle CDC

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

  2. Baseline Design sBelle Belle

  3. Main parameters

  4. Wire Configuration Present CDC 250 mm 1200 mm New CDC 250 mm

  5. 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.

  6. Prototype of readout board by Y. Igarashi Under 20cm • 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 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, 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%) Fe55 5.9keV X-ray Amp Receiver Tungsten wire Small tube chamber

  8. 40ns 100ns 40ns Comparison HV=1.7kV ~300mV Belle AMP ●Belle AMP ■ATLAS ASD ▲T-ASD Pulse height [mV] ~220mV ATLAS ASD ~140mV HV [kV] T-ASD

  9. HV=1.9kV ~600mV saturate HV=1.9kV ~600mV distorted Comparison Noise level ~5mV ~3mV ~5mV T-ASD Belle AMP ATLAS ASD Saturation T-ASD 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 MC+BGx20

  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). Talk by T. Kawasaki Preliminary By H.Ozaki 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 BgD*D* 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 Just after wire stringing Installation in 2003 summer

  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(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

  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(SVD+CDC) • 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(>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.

  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. He/C2H6 = 50/50 Pure CH4 Drift time (msec) 100nsec 100nsec Distance from wire (cm) 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 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), Field:300mm(80g) • Total tension 4.8ton • Stress calculation • Thickness of outer cylinderCFRP：mm • 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. dE/dx Resolution measurement (%) Sampling width (nsec) 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

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