Super-IFR Detector R&D summary

1. Super-IFR Detector R&D summary Wander Baldini on behalf of the superB-IFR group: Ferrara, Padova, Roma1 INFN and University Detector R&D Workshop, SLAC Feb. 14-16 2008

2. OVERVIEW • The SuperB IFR • The baseline structure/ detection technique • Present status of the detector R&D • Ongoing activities • Detector optimization studies • Future activities • Future detector R&D short term activities • From CDR to TDR • Conclusions W. Baldini, INFN sez. di Ferrara

3. Baseline detector structure • rate too high for gas detectors  scintillator bars with blue to green WLS fibers light collection (Minos-like technique) • Reuse Babar flux return with additional iron for better muon ID • 8 active layers in both barrel/endcaps • Keep longitudinal segmentation for KL ID • optimization according to MC W. Baldini, INFN sez. di Ferrara

4. Scintillator bars + WLS fibers readout on both ends by Geiger mode APDs Baseline Detection Technique • Scintillator: • 4 cm scintillator bars covered with TiO2 • Light collection through WLS fibers • Fibers housed in a surface grove / embedded hole(s) • WLS fibers: • f = 1mm type Y11(200/300) (Kuraray) or BCF92 (Saint Gobain), Attenuation length l ≈3.5m, trapping efficiency ε ≈ 5.5% • Fibers readout: • Multi Pixel Photon Counters (Hamamtsu), Silicon Photo Multiplier (IRST Trento-Italy): • Gain >105, DE ≈ 40% (@ 500 nm, MPPC) (DE = Q.E x Fill factor x Avalanche probability) • < 1ns risetime • Low bias voltage (35V SiPM, 70V MPPC) • Dark current rate @ room temperature : 100s of kHz @ 0.5 phe, few 10s of kHz @ 1.5 phe, few kHz @ 2.5 phe W. Baldini, INFN sez. di Ferrara

5. Geiger mode APDs SiPM MPPC • Avalanche photodiodes operated a few Volts above the breakdown voltage • Dark count rate too high for large active areas  matrices of small (~ 50μm) cells in parallel • A single cell signal for each photon W. Baldini, INFN sez. di Ferrara

6. Detector R&D activities W. Baldini, INFN sez. di Ferrara

7. MPPC module Cosmic test setup Cosmics Test Setup R&D in Ferrara • Tests with cosmics • scintillator: 1.5cmx2.0cm, with 1 embedded hole (one fiber), 2m long • WLS fiber: Saint Gobain BCF92, f = 1mm, ≈ 4m long • Fibers Readout: • Both ends MPPC “plug and play” module (Hamamatsu), 1.2mm active area • SiPM on one end (very preliminary!) 1.2 mm active area Scintillator bar WLS FIBER MPPC W. Baldini, INFN sez. di Ferrara

8. Cosmic ray test setup 15cm S1 Scintillator (2m long) S2 MPPC2 / SiPM WLS fiber (4m long) MPPC1 ADC F/O DISCR TDC S1xS2 Gate to ADC Common Start toTDC W. Baldini, INFN sez. di Ferrara

9. Light Yield ADC spectrum for MPPC 350 cm far from the trigger pedestal 4 phe 3 phe Average number of phe 2 phe 1 phe adc channels ADC spectrum for MPPC 50 cm far from the trigger Distance from photodetector (cm) SiPM pedestal adc channels adc channels Average number of phe:~ 9 at maximum distance (4m) ADC spectrum from SiPM 200 cm far from the trigger W. Baldini, INFN sez. di Ferrara

10. Detection efficiency and dark counts • Efficiency > 90% but can be improved because the trigger system has not yet been optimized • If we require also one MPPC signal in the trigger we obtain an efficiency for the other MPPC> 99% SiPM very preliminary results: ~ 90% @ room temperature (not stabilized) and 36V bias voltage Dark count rates of SiPM are roughly a factor 2 higher W. Baldini, INFN sez. di Ferrara

11. Distance ~200 cm sigma 1.8 ns Distance ~200 cm sigma 1.3 ns counts MPPC SiPM Time resolution for different cut on ADC ch MPPC • 150 cm • 250 cm Time resolution (ns) ADC ch Time resolution • For these first measurements no constant fraction discriminator was used because we wanted to understand how the time resolution depends on the strength of the signal Time (ns) • 15 cm scintillators has been used in the trigger • Time measured with respect • to the trigger signal (common start) W. Baldini, INFN sez. di Ferrara

12. MPPC module SiPM Amplifier Rpz (optional) - - 10x@1.8GHz Pre_Out 10x@1.8GHz Cpz SiPM THS4303 THS4303 A.C.R. Jan 28 2008 NEG_Vbias Front End Electronics: SiPM Amplifier • The MPPC modules comes with (unknown) FE electronics • For the SiPM devices a prototype amplifier has been developed based on commercial Texas Instrument THS4303 fast amplifier • The idea is to preserve as much as possible the very fast leading edge of the SiPM signal (~ 200psec) to minimize the time spread • CF discri-TDC vs ADC-TDC option to be evaluated W. Baldini, INFN sez. di Ferrara

13. Detector optimization studies W. Baldini, INFN sez. di Ferrara

14. Simulations • Full simulation needed to optimize the detector • Started some studies in Ferrara-Padova • Basic “zero order” idea: • use the existing BaBar code with superB-modified geometry • simulation of background adding noise to the present IFR according to background distributions • Once the optimal parameters are found they will be used in the fast simulation for physics study and better detector optimization • People involved: Andreotti, Negrini, Munerato, Cibinetto (Ferrara), Rotondo (Padova) W. Baldini, INFN sez. di Ferrara

15. Future Activities W. Baldini, INFN sez. di Ferrara

16. From CDR to TDR (I) • WLS studies: • Different types (Kuraray vs Saint Gobain) and dopant concentration (200 - 300 ppm) • Time response: Kuraray-T11 (≈10 ns), Saint Gobain-BCF 92 (≈ 2.7 ns) • Scintillator studies: • Position of the grooves (surface or embedded) and scintillator thickness for sufficient photoelectron number • Studies on SiPM/MPPC: • Gain, dark counts rate, stability Gain vs Voltage and Temperature • Ageing: I vs V, Gain, dark count, measured periodically after keeping the devices ON and exposed to light • radiation tests • Spread of the parameters among devices • Mechanics • Develop various procedures: coupling photodet./fiber, assembly of single slab and module, installation..... W. Baldini, INFN sez. di Ferrara

17. From CDR to TDR (II) • Measurements on scintillator + WLS + photodetector with cosmics/source: • Number of photoelectrons • Detection Efficiency • Time and space resolution • Possible FE electronic options: • CF discriminator • TDC and ADC (for timing correction) • Montecarlo simulations • Performance requested (z and phi resolutions) • Optimization of the detector layout (dimension of scintillator slabs, number of layers, ...) • Need interaction with people working on background • Test beam of a complete module in the final configuration W. Baldini, INFN sez. di Ferrara

18. Conclusions • Detector R&D activities started, preliminary results are encouraging: • Average number of phe: 9 < Nphe<15 with ONE 1mm fiber and a 1.5 mm thick scintillator with embedded groove • Detection efficiency: > 90% but an optimized trigger will certainly improve it (relative efficiency to other photodetector ~ 99%) • Time resolution: < 2.0 nsec with 15 cm trigger selection, no CFD, SiPM shows better resolution • Simulations studies started • Good opportunity for other groups to join the superB-IFR effort W. Baldini, INFN sez. di Ferrara

19. SPARE SLIDES W. Baldini, INFN sez. di Ferrara

20. BaBar IFR 2002 studies • Studies have been done in 2002 for the BaBar IFR barrel upgrade to use scintillator + WLS fibers + APD as a possible option • 4cm wide scintillator bars (2 types: ITASCA/AMCRYS) covered with TiO2 readout through 4 WLS fibers and APD (RMD Mod. S0223) readout on both ends • WLS fibers Kuraray Y11, round Φ=1.2mm, multiclad • 4 fibers on the same APD pixel to increase the amount of light • Detection Efficiency = 98% with APD cooled at 0º C • Space resolution 70cm due to poor APD/preamplifier time resolution (total risetime ~100ns) From: P.Kim Hawaii SuperB factory workshop, Jan 19-22 2004, and Rafe H. Schindler, Status Report for the Scintillator Option for the IFR Replacement, Nov. 14 2002 W. Baldini, INFN sez. di Ferrara

21. Scintillator Bars • In contact with FNAL-NICADD facility • Various candidates: • There are some spares, from Minerva, Minos, etc.. that could be used for R&D purposes W. Baldini, INFN sez. di Ferrara

22. WLS fibers R&D • Baseline:Kuraray Y11-175 Φ=1.0 mm, round, double cladding • Trapping efficiency = 5.4% • Attenuation Length ~ 3.5m • Emission peak: 476 nm • Possible alternatives: • Different diameter/dopant concentration: increase the light yield • Square shape: higher trapping efficiency (~+30%) • Bicron BCF-92 fibers (round multiclad): • Trapping efficiency = 5.6% • Attenuation Length ~ 3.5m • Emission peak: 492 nm • Decay time: 2.7 ns (Y11-200 is ≈10ns), faster → better time resolution W. Baldini, INFN sez. di Ferrara

23. APDs vs Geiger mode APDs • APD: • For BaBar R&D was considered the model RMD #S0223: • G>1000 • QE=65% (>530 nm) • 5ns risetime • High bias voltage (1850V)  difficult to stabilize • G very sensitive to V and T variations • Hamamatsu APDs have lower gain (few 100), bias voltage 400- 500 V Geiger mode APDs: • MPPC (Hamamatsu), SiPM (FBK- IRST) • G >105 • DE ≈ 40% (530nm) (DE = Q.E x Fill factor x Avalanche probability) • ~ 1ns risetime • ≈ 10 times less sensitive to V and T variations • Low bias voltage (30-70V) • Dark current rate @ room temperature : 100s of kHz thr = 0.5 phe 10s of kHz if thr = 1.5 phe W. Baldini, INFN sez. di Ferrara