IFR Detector R&D status Wander Baldini On behalf of the Ferrara SuperB group SuperB Workshop, SLAC Oct 5-9 2009

W. Baldini, INFN sez. di Ferrara Detection Technique Scintillator bars + WLS fibers readout on both ends by Geiger mode APDs Scintillator: 2x4x400 cm3 scintillator bars coated with TiO2 Light collection through WLS fibers Fibers housed in a surface grove or in an embedded hole WLS fibers: f = 1.0 or 1.2 mm type Y11(200/300) (Kuraray) or BCF92 (Saint Gobain), Attenuation length l ≈ 3.5m, trapping efficiency ε ≈ 5.5% Photodetectors: Multi Pixel Photon Counters (Hamamtsu), Silicon Photo Multiplier (IRST-FBK 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, few MHz @ 1.5 phe, few 100s kHz @ 2.5 phe, few 10 KHz @ 3.5 p.e. W. Baldini, INFN sez. di Ferrara

W. Baldini, INFN sez. di Ferrara Detector Layout 2 layouts under study: time readout, double coordinate digital readout Time readout: azimuthal coord f measured from the hit bar, polar coord q from the arrival time of the signal Double coord binary readout: two layers of orthogonal scintillating bars provide directly the f and q coordinates. Easier from the point of view of electronics but more complicated for the mechanics W. Baldini, INFN sez. di Ferrara

W. Baldini, INFN sez. di Ferrara Readout To reduce the radiation effects on SiPM ,we considered the option of bringing the light signal out of the detector through clear fibers, but the light loss in the needed 10m of clear fibers is too high (factor 3) Increasing the number of WLS fibers (for scintillating bar) to 3 or 4 allows us to recover only a factor < 2, when coupled to clear fibers So the SiPM have to be coupled directly to WLS fibers and put on the detector (and properly shielded). The signal from SiPM will be brought to the FE electronics (kept out of the detector) through ~ 8-10m long shielded cables W. Baldini, INFN sez. di Ferrara

Update on detector R&D activities in Ferrara  W. Baldini, INFN sez. di Ferrara

Measurements after Perugia Workshop We have measured the efficiency AND time resolution (for the time readout option) for 10mm and 20 mm thick scintillator bars for the following configurations: 2 and 3 WLS fibers directly coupled to SiPM (no clear fibers) 1.0 Bicron and 1.2 mm 1.5, 2.5, 3.5 p.e. thresholds Good 2x2 mm2 SiPM (FBK) and irradiated (1.25 x 1010 n/cm2) Scintillator-fibers coupling with/without optical grease 20mm 10mm Binary readout Time readout W. Baldini, INFN sez. di Ferrara

W. Baldini, INFN sez. di Ferrara Cosmic ray test setup S1 SiPM 2x2 WLS fibers Scintillator S2 SiPM 2x2 Prototype inputs Discrim. out TDC S2 Trigger = S1 x S2 trigger inputs S1 DAQ Fast discriminator / trigger board W. Baldini, INFN sez. di Ferrara

W. Baldini, INFN sez. di Ferrara The setup Dark Box two 1.0 cm thick scintillators “sandwiched” tfor the time readout Trigger scintillators WLS fibers on a 2x2 mm2 SiPM W. Baldini, INFN sez. di Ferrara

W. Baldini, INFN sez. di Ferrara Working conditions SiPM: Vbias = 33.0 V Thresholds: 1.5, 2.5, 3.5 p.e. Fiber length: 2.4m, ϕ=1.2mm kuraray, for 10 mm scintillator 2.2m, ϕ=1.0mm Bicron, for 20 mm scintillator Trigger: 5cm scintillator, readout with 2 MPPC modules (thresholds @ ~ 4 p.e.) Time reference given by a fast PMT FE electronics: Amplifier Bias Comparator board (ABC) developed in Ferrara by A. Cotta and R. Malaguti, based on MMIC fast amplifiers data samples ~ 1000 events (tipically 1 night) Efficiency calculated using only TDC W. Baldini, INFN sez. di Ferrara

Binary readout Time resolution Efficiency 1 fiber 2 fibers 3 fibers * 1.5pe 2.5pe 3.5pe 1 fiber 2.4 m 2.06 2.26 2.48 96.4% 93.0% 83.3% 2 fibers 1.87 2.16 2.14 98.8% 97.4% 91.6% 2.4 m (no grease) 2.30 2.49 2.64 97.2% 94.9% 85.7% 3 fibers 1.60 1.65 1.76 98.7% 99.2% 98.5% 2.4 m (bicron) 1.41 1.58 1.79 96.6% 93.6% 86.0% * Tests with 3 kuraray fibers and no grease to be done, we expect a few % loss * All Kuraray ϕ=1.2 mm unless otherwise stated 10

Time readout option * * All Bicron ϕ=1.0 mm Time resolution Efficiency 1.5 pe 2.5pe 3.5pe 1.5pe 2 Fib. 0.3m 0.91 0.95 --- 95.4% 98.6% 2.2 m 1.38 1.44 95.9% 96.5% 3 Fib. 0.89 0.97 94.2% 98.9% 99.4% 2.2m (no grease) 1.16 (1.32) 1.17 (1.37) 1.26 (96.1%) 99.1% (97.4%) (94.4%) * Dark counts: 2.4MHz-1.5pe, 450kHz-2.5pe, 50kHz-3.5p.e. Vbias=33V * All Bicron ϕ=1.0 mm

Time readout option with irradiated SiPM: 1.25x1010 n/cm2 Time resolution Efficiency 1.5 pe 2.5pe 3.5pe 1.5pe 2 Fib. Close End --- Far End 1.80 1.74 81.4% 84.4% 3 Fib. 0.99 1.10 89.5% 97.8% 1.38 1.41 89.7% 95.5% Dark counts: 4.2MHz -1.5pe, 1.0MHz - 2.5pe, Vbias=32V

W. Baldini, INFN sez. di Ferrara Some comments... The 3 fibers option allows us to reach the desired parameters (Tres ~ 1ns, Eff>95%) on both readouts A dose of 1.25 x 1010 neutrons does not spoil too much the performances, but of course devices have to be properly shielded. Precise simulation on expected dose is very important The devices are rather noisy and gets ~ a factor 2 worse when irradiated, put threshold @ 3.5 p.e. will reduce it ~ factor 10 The noise affect also the efficiency due to accidentals (e.g. 1.5 p.e. eff is lower than 2.5 p.e.) and time resolution Putting no optical grease reduce ~ 2-3% eff but would greatly simplify the assembly process W. Baldini, INFN sez. di Ferrara

Proposed baseline configuration Tested Baseline 20mm New Dye 400mm Aluminum foil Already existing dye with 2 holes… 10mm 400mm In the “baseline” version we expect to collect more light than in the tests version W. Baldini, INFN sez. di Ferrara

W. Baldini, INFN sez. di Ferrara Some comments...(II) For the 20mm scintillator: we will ask for a new dye since no 20mm x 400mm dye exists at the FNAL-NICADD facility For the 10mm scintillator: a production of 10mm x 400mm scintillator with 2 embedded holes is forseen by the end of the year Given the small amount (120 bars, 60cm long) we might have them almost for free… we can then add a central groove to house the additional fiber, this is OK for the prototype W. Baldini, INFN sez. di Ferrara

Conclusions and next steps The 3 fibers configuration allows us to reach the desired parameters Some tests still to be done but the baseline configuration is almost defined In contact with the FNAL-NICADD (scintillator) and with FBK and Hamamatsu (photosensors) to arrange productions for the prototype Place orders as soon as possible W. Baldini, INFN sez. di Ferrara