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

2. W. Baldini, INFN sez. di Ferrara2 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

3. W. Baldini, INFN sez. di Ferrara3 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 K L ID optimization according to MC

4. W. Baldini, INFN sez. di Ferrara4 Baseline Detection Technique Scintillator: –4 cm scintillator bars covered with TiO 2 –Light collection through WLS fibers –Fibers housed in a surface grove / embedded hole(s) WLS fibers: –  1mm type Y11(200/300) (Kuraray) or BCF92 (Saint Gobain), Attenuation length  ≈  3.5m, trapping efficiency ε ≈ 5.5% Fibers readout: –Multi Pixel Photon Counters (Hamamtsu), Silicon Photo Multiplier (IRST Trento-Italy): Gain >10 5, 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 Scintillator bars + WLS fibers readout on both ends by Geiger mode APDs

5. W. Baldini, INFN sez. di Ferrara5 Geiger mode APDs MPPC SiPM 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 Dark count rate too high for large active areas  matrices of small (~ 50μm) cells in parallel A single cell signal for each photon A single cell signal for each photon

6. W. Baldini, INFN sez. di Ferrara6 Detector R&D activities

7. W. Baldini, INFN sez. di Ferrara7 R&D in Ferrara Cosmic test setup Cosmics Test Setup MPPC module Scintillator bar WLS FIBER MPPC Tests with cosmics scintillator: 1.5cmx2.0cm, with 1 embedded hole (one fiber), 2m long WLS fiber: Saint Gobain BCF92,  1mm, ≈ 4m long Fibers Readout: 1.Both ends MPPC “plug and play” module (Hamamatsu), 1.2mm active area 2. SiPM on one end (very preliminary!) 1.2 mm active area

8. W. Baldini, INFN sez. di Ferrara8 Cosmic ray test setup TDC ADC DISCR F/O MPPC1 MPPC2 / SiPM Scintillator (2m long) S1 S2 S1xS2 Gate to ADC Common Start toTDC WLS fiber (4m long) 15cm

9. W. Baldini, INFN sez. di Ferrara9 Light Yield Light Yield adc channels 1 phe 2 phe 3 phe 4 phe pedestal ADC spectrum for MPPC 350 cm far from the trigger adc channels ADC spectrum for MPPC 50 cm far from the trigger Distance from photodetector (cm) Average number of phe Average number of phe: ~ 9 at maximum distance (4m) adc channels pedestal ADC spectrum from SiPM 200 cm far from the trigger SiPM

10. W. Baldini, INFN sez. di Ferrara10 Detection efficiency and dark counts 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 Threshold(phe)Rate (kHz) 0.5~300 1.5~ 30 2.5~ 3 Dark count rates of SiPM are roughly a factor 2 higher

11. W. Baldini, INFN sez. di Ferrara11 Time resolution Time (ns) Time resolution for different cut on ADC ch ADC ch Time resolution (ns) 150 cm 250 cm MPPC 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 counts Distance ~200 cm sigma 1.3 ns Distance ~200 cm sigma 1.8 ns MPPC SiPM 15 cm scintillators has been used in the trigger Time measured with respect to the trigger signal (common start)

12. W. Baldini, INFN sez. di Ferrara12 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 NEG_Vbias - Pre_Out SiPM SiPM Amplifier R pz (optional) C pz - A.C.R. Jan 28 2008 10x@1.8GHz THS4303 MPPC module

13. W. Baldini, INFN sez. di Ferrara13 Detector optimization studies

14. W. Baldini, INFN sez. di Ferrara14 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)

15. W. Baldini, INFN sez. di Ferrara15 Future Activities

16. W. Baldini, INFN sez. di Ferrara16 From CDR to TDR (I) 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.....

17. W. Baldini, INFN sez. di Ferrara17 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 From CDR to TDR (II) From CDR to TDR (II)

18. W. Baldini, INFN sez. di Ferrara18 Conclusions Detector R&D activities started, preliminary results are encouraging: –Average number of phe: 9 < N phe <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

19. W. Baldini, INFN sez. di Ferrara19 SPARE SLIDES

20. W. Baldini, INFN sez. di Ferrara20 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 TiO 2 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

21. W. Baldini, INFN sez. di Ferrara21 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

22. W. Baldini, INFN sez. di Ferrara22 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

23. W. Baldini, INFN sez. di Ferrara23 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 >10 5 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