1. Vertex detector for the KEK B factory upgrade Toru Tsuboyama (KEK) 1 March 2008 Instr08 Novosibirsk

2. Introduction 1 March 2008 NovosibirskSilicon Vertex Detector for the KEKB factory upgrade Toru Tsuboyama (KEK) 2

3. 1 March 2008 Novosibirsk Silicon Vertex Detector for the KEKB factory upgrade Toru Tsuboyama (KEK) 3 Super Belle detector (LoI ‘04) SC solenoid 1.5T New readout and computing systems Aerogel Cherenkov counter + TOF counter  / K L detection 14/15 lyr. RPC+Fe  tile scintillator CsI(Tl) 16X 0  pure CsI (endcap)  “TOP” + RICH Tracking + dE/dx small cell + He/C 2 H 6  remove inner lyrs. use fast gas Si vtx. det. 4 lyr. DSSD  2 pixel/striplet lyrs. + 4 lyr. DSSD

4. Purpose of the Silicon Vertex Detector  SVD reconstructs two vertices of B decay.  B flight length ~ 200  m.  The CP violation parameters are extracted from the distribution of distance between two vertices. Silicon Vertex Detector for the KEKB factory upgrade Toru Tsuboyama (KEK)4 Belle 2005 J/  KSKS ee ee Decay time difference tt Belle SVD (4 layer) 50 cm 20 cm 1 March 2008 Novosibirsk

5. Super KEKB upgrade  The present KEKB has established the CP violation in the framework of the Standard Model by using ~1 ab -1 of data.  Further investigations needs 10-50 ab -1 data.  Examination of the unitarity of the CKM matrix.  Measurement of the CP violation phase coming from Penguin diagrams.  Rare decay of the B mesons, charmed mesons and lepton flavor violation of .  Any deviation from the standard model prediction suggests existence of new phenomena such as SUSY.  A Super B factory with L=10 35 -10 36 /cm 2 /sec is necessary.  Measurements by LHC and Super B factory experiments are complementary. 1 March 2008 NovosibirskSilicon Vertex Detector for the KEKB factory upgrade Toru Tsuboyama (KEK)5

6. 1 March 2008 NovosibirskSilicon Vertex Detector for the KEKB factory upgrade Toru Tsuboyama (KEK)6

7. Current SVD 1 March 2008 NovosibirskSilicon Vertex Detector for the KEKB factory upgrade Toru Tsuboyama (KEK) 7

8. Present SVD 1 March 2008 NovosibirskSilicon Vertex Detector for the KEKB factory upgrade Toru Tsuboyama (KEK)8  Has been working since 2003 Autumn.  4 layer DSSD ladders are read out with VA1TA chips. DSSDs Kapton flex circuit VA1TA r = 2.0, 4.35, 7.0, 8.8 cm

9. Limitations of the present SVD 1 March 2008 NovosibirskSilicon Vertex Detector for the KEKB factory upgrade Toru Tsuboyama (KEK)9  Readout ASIC: VA1TA  VA1 is an excellent ASIC designed for the KEK B factory.  Each event causes a dead time of about 30  sec.  5 % dead time at 1.6 KHz trigger rate.  No problem at the current trigger rate of 500 Hz.  Hit occupancy of the innermost layer.  KEKB luminosity exceeded the design value.  So do the beam backgrounds entering to SVD.  At occupancy larger than 10 %, vertexing performance will be deteriorated significantly.  Shaping time of VA1TA, 0.8  sec, is longer than that of modern readout chips.  Four layer design.  Vertexing and self tracking is possible, though, the redundancy is minimum. Occupancy in the first layer Hit finding efficiency

10. Our choice 1 March 2008 NovosibirskSilicon Vertex Detector for the KEKB factory upgrade Toru Tsuboyama (KEK)10  6 layer  For robust vertexing and tracking  Outer radius: 14 cm  High Ks reconstruction efficiency  Inner radius: 1.0 cm  For better vertex resolution.  Readout chip: APV25  Reduction of occupancy from beam background.  Pipelined readout to reduce readout dead time.  Sensor of the innermost layer:  Normal DSSD  Short-strip DSSD  Pixel sensors  Depends on the available technology  Background is proportional to the sensitive area per channel.

11. Design philosophy of the upgrade SVD 1 March 2008 NovosibirskSilicon Vertex Detector for the KEKB factory upgrade Toru Tsuboyama (KEK)11  Requirements from physics  To reconstruct vertices of two B mesons with ~100  m resolution.  Reconstruct slow pions decaying from D*.  Lager radius in order to improve Ks reconstruction efficiency.  Better impact parameter resolution would result in better suppression of continuum events.  Constraints  Ready for physics at the Super KEK B factory commissioning  Immunity to the expected backgrounds from the accelerator.  Effects of material should be carefully evaluated and minimized.  Data acquisition  Should work efficiently at the luminosity goal of ~10 36 /cm 2 /sec.  Pipelined readout to minimize the dead time.  Negligible dead time at 10 kHz average trigger rate.

12. Detector configuration 1 March 2008 NovosibirskSilicon Vertex Detector for the KEKB factory upgrade Toru Tsuboyama (KEK)12  6 layers for robust tracking.  R=1.0 cm beam pipe. First layer R=1.3 cm.  Outermost layer: R=14 cm.  Acceptance of Ks is increase by 15 %.  Slanted sensors: Reduce sensor area and number of readout channels. Material is also saved. r =150mm (cm) 17°

13. Readout system 1 March 2008 NovosibirskSilicon Vertex Detector for the KEKB factory upgrade Toru Tsuboyama (KEK) 13

14. Readout with APV25 ASIC  Developed for CMS Silicon tracker.  Shaping time of the preamplifier: 50 nsec  Occupancy: 1/16 compared with VA1TA (800 nsec).  Operated with 40MHz clock  192 stage pipeline (~4 µsec trigger latency)  Up to 32 readout queues  128 ch analog multiplexing (3 µsec@40 MHz)  Dead time: negligible at expected trigger rate of 10 kHz 1 March 2008 NovosibirskSilicon Vertex Detector for the KEKB factory upgrade Toru Tsuboyama (KEK)14 Shaper Inverter preamp 192 stageAnalog Pipeline (4 µsec) Analog output Trigger 128 channel Multiplexer (3 µsec) Noise= (246 + 36/pF) @50nsec

15. Hit timing reconstruction  KEK B-Factory: 2 nsec bunch crossing  Built-in deconvolution filter (assuming the LHC 25 nsec bunch crossing) can not be used.  Hit time reconstruction  Read out 3, 6 … slices in the pipeline.  Extract the hit timing information from the wave form.  Proved in beam tests: Resolution ~ 2 nsec. 1 March 2008 NovosibirskSilicon Vertex Detector for the KEKB factory upgrade Toru Tsuboyama (KEK)15 Shaper Trigger

16. APV25 readout system 1 March 2008 NovosibirskSilicon Vertex Detector for the KEKB factory upgrade Toru Tsuboyama (KEK)16  Readout scheme suitable for Belle has been developed: Hybrid, Repeater system, FADC and DAQ.  Series of beam test has been done by in order to understand APV25 and to accumulate experiences.  Nov. 2007: The first experiment at the KEK new test beam line.  Demonstration of the new DSSD sensor, hybrid, repeater and FADC.  CM subtraction, cluster search and hit- time reconstruction done in FPGA is tried.  Poster presentation by Vienna HEPHY group in this conference.

17. Chip-on-sensor concept 1 March 2008 NovosibirskSilicon Vertex Detector for the KEKB factory upgrade Toru Tsuboyama (KEK) 17

18. Chip-on-sensor readout 1 March 2008 NovosibirskSilicon Vertex Detector for the KEKB factory upgrade Toru Tsuboyama (KEK)18  APV25 has a steeper noise slope than VA1TA  VA1TA Noise=(180+7.5/pF) e / APV25 Noise=(180+ 36/pF) e  Several DSSDs can be read out with one VA1TA hybrid.  In case of APV25, a DSSD should be readout by one hybrid.  Chip-on-sensor concept.  Mounting APV25 chips directly on sensors.  Increase of material due to not only chip itself but also support and cooling structure should affect the vertex performance.

19. Effects of material increase  In order to evaluate the performance of 6 layer SVD with APV25 chip-on- sensor design, intensive simulations have been done. Results have been reported in the workshop by A. Kibayashi.  Conclusions are  Chip on sensor readout for the innermost 2 layers would deteriorate the vertex performance.  Material increase in layer 3-6 does not reduce the vertex performance significantly.  High-multiplicity events (D+D-) is especially sensitive to material.  B  K*  is special as only Ks can be used to estimate the B decay vertex. Efficiency improves thanks to layers 5 and 6. 1 March 2008 NovosibirskSilicon Vertex Detector for the KEKB factory upgrade Toru Tsuboyama (KEK)19 Bench mark B   +  -B  J/  Ks B  D+D- B  K*  No “chip-on-sensor”  =31  m  =38.7 %  =36  m  =24.9 %  =43  m  =13.2 %  =127  m “chip-on-sensor” in Layers 1 and 2  =34  m  =38.3 %  =40  m  =24.6%  =51  m  =12.7 % “chip-on-sensor” in Layers 3 and 4  =31  m  =38.1 %  =36  m  =24.5 %  =42  m  =12.6 %  =137  m (T. Hara)

20. DSSD and pixel sensor R&D 1 March 2008 NovosibirskSilicon Vertex Detector for the KEKB factory upgrade Toru Tsuboyama (KEK) 20

21. DSSD 1 March 2008 NovosibirskSilicon Vertex Detector for the KEKB factory upgrade Toru Tsuboyama (KEK)21  HPK stopped DSSD production.  Single sided sensors are too thick to be used in e + e - B factories.  New DSSD sources  Micron semiconductor, UK.  Experienced with Babar, LHCb, CDF, D0 ….  Can produce 300  m-thick DSSDs from 6” diameter wafers  Design flexibility.  Tata institute (Belle collaborator)  Produced single-sided sensors for the CMS experiment.  DSSD production is in progress with a foundry in Bangalore.  The sample will be available in April or May.  Kyumpook Univ. (Belle collaborator)  AC-coupled single-sided and DC coupled double- sided sensors are now under evaluation.  Design of an AC-coupled double-sided sensors are in preparation.

22. Striplet option  The innermost layer suffers huge beam background.  Occupancy reduction by APV25 may not be sufficient  By inclining the strips by 45 degrees, strip area per readout channel can be reduced to almost 1 / 4, in expense of 4x readout channels. 1 March 2008 NovosibirskSilicon Vertex Detector for the KEKB factory upgrade Toru Tsuboyama (KEK)22 Striplet

23. Striplet 2003 1 March 2008 NovosibirskSilicon Vertex Detector for the KEKB factory upgrade Toru Tsuboyama (KEK)23 Parameterspn Sensitive area (mm 2 )71.0x7.9 Strip length (mm)10.5 Strip pitch (µm)25.5 (p)51 (n) Readout pitch (µm)51 (p)51 (n) Num. of readout ch.1024 Bias resistor (M  ) >10 71 mm 7.9 mm

24. Monolithic pixel sensors  Pixel sensors are the solution to reduce the hit occupancy.  Monolithic pixel sensor should be used.  Hybrid sensors are too thick to be used in B factories.  Innermost layer can be replaced with pixel sensor later.  January 2007 submissions.  CAP (Hawaii) --- Monolithic Pixel Sensor project  Several iterations have been done.  CAP7 --- the concept is implemented in SOIPIX.  Binary readout.  SOIPIX (KEK, TIT et al.)  Continuous amplifier, time-over-threshold and simple digital pipeline is implemented. 1 March 2008 NovosibirskSilicon Vertex Detector for the KEKB factory upgrade Toru Tsuboyama (KEK)24 CAP7

25. Summary 1 March 2008 NovosibirskSilicon Vertex Detector for the KEKB factory upgrade Toru Tsuboyama (KEK) 25

26. SVD construction schedule 1 March 2008 NovosibirskSilicon Vertex Detector for the KEKB factory upgrade Toru Tsuboyama (KEK)26

27. The SVD upgrade kick-off meeting 1 March 2008 NovosibirskSilicon Vertex Detector for the KEKB factory upgrade Toru Tsuboyama (KEK)27  20 Feb 2008, just before this BPAC.  Summary of the 3 to 4 years R&Ds.  Please visit http://kds.kek.jp/conferenceDisplay.py?confId=865http://kds.kek.jp/conferenceDisplay.py?confId=865  Today’s presentation is a summary of this meeting. Overview 09:30 Schedule (T. Tsuboyama, KEK) 09:40 CDC inner radius (S. Uno, KEK) 09:45 Beam pipe (H. Yamamoto, Tohoku) 09:55 Overall design (T. Kawasaki, Niigata) 10:25 Structure / Ladder (O. Tajima, KEK) Electronics I 11:15 Pixel, ASIC... (G. Varner, Hawaii) 11:45 Pixel-- SoI technology (H. Ishino, TIT) DSSD 13:00 HPK/Micron (T.Tsuboyama, KEK) 13:10 DSSD in Korea (H. Hyun, Kyungpook) Software 14:00 Overview (T. Hara, Osaka) 14:20 Demonstration for the Fallback option (Y.Kuroki, Osaka) 14:40 Simulation for Baseline option (A.Kibayashi, KEK) 15:00 Pixel Simulation (H. Hoedlmoser, Hawaii) 15:10 Tracking for SVD5.1 ? (K.Trabelsi, KEK) 15:30 Requirement for Alignment precision (T.Hara, Osaka) Performance study 16:00 Outer layer (I) radii (T.Hara for S.Shinomiya, Osaka) 16:10 Outer layer (II) S/N and readout ptch (, Niigata) 16:20 Material --- ASIC on DSSDs (T.Hara, Osaka) 16:30 Readiness of fsim6 (C. Schwanda, Vienna) Electronics II 17:00 APV25 and APV25 hybrid (C. Irmler, Vienna) 17:10 DAQ overview (M. Friedl / M. Pernicka, Vienna) 17:40 Activities in Cracow (H. Palka, INP Cracow) 18:00 Monitors (S. Stanic, Nova Gorica) 18:20 Diamond radiation monitor (S. Korpar, Ljubljana)