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Sci-Fi tracker for IT replacement 1 Guido.Haefeli@epfl.ch Lausanne 9. December 2010 Slide 2 2 Commercial available SiPMs (MPPCs) from Hamamatsu Slide 3 Customized 128 CH MPPC array for Sci- Fi tracker use Array optimized for small dead aera between modules Optimized for high channel number on one module For the use in LHCb and PEBS A total = 0.25mm x 1.2mm x 128 A pixel =50um x 50um N pixel =88 G=0.75x10 6 e/PE N channel = 128 3 32mm Slide 4 Fiber tracker for LHCb IT 4 Bonding wires Rectangular channels Cross section view Reduce epoxy layer to decrease diffusion Slide 5 Fiber tracker for LHCb IT 5 Slide 6 6 Slide 7 7 Slide 8 IT replacement detector box 8 Slide 9 Measurements with 25,50 and 100um pixel detectors 9 1mm2, 50umx50um F dark =0.4MHz 1mm2, 50umx50um 9mm2, 100umx100um F dark =10MHz 2mm2, 25umx25um F dark =0.6MHz Slide 10 Adaptation of the Beetle input circuit for the use with an SiPM 10 Silicon stripSiPM 0.25mmx1.2mm 50um pixel Detector capacitance10-15pF10pF Gain22ke/MIP (300um Si) 0.75*10 6 /Pe (15Pe /MIP) Rel Gain / MIP1511 Load resister required for fast readout (25ns) ~1kOhm100-200 Ohm Dynamic range0..5MIP0..3MIP (reduce signal by 300) Why do we need an adaption? Difference between the SiPM and the silicon strip readout. Slide 11 Model of SiPM (1mmx1mm, 50um pixel) voltage on R s 11 Adjusted the model of the SiPM to the measured pulses, the graphs show voltage on Rs Note that the pulse height is different for different R s. Slide 12 Model of SiPM (1mmx1mm, 50um pixel) Charge Q 12 Adjusted the model of the SiPM to the measured pulses, the graphs show the current and the charge injected to the Beetle from the 120fC = 0.75*10 6 e The simulation shows the values for different R s. The charge is equal for all R s Slide 13 Beetle response for different injection time 13 The arrival of several photons on the detector slows down the rise time of the pulse of the detector measured at Rs, this doesnt result in a different charge injected. The falling edge fast time constant is responsible for a partial discharge during the arrival of the different photons. Note that the pulse height is different for different length o interval of injection time. Slide 14 Beetle response with SiPM signal Different injection interval (0.5ns, 1ns, 2ns, 4ns, and 10ns) to observe the effect of the arrival of a pulse with different arrivals of the photons. Only with 10ns some degradation is observed. Response height is almost the same. 14 R-R current divider is used. Slide 15 Injection prototype with Beetle FE chip 15 Use the IT hybrid with Beetle 1.3 Using the Velo analog data signal chain for DAQ (repeater, analog cable, ADC on Tell1 Attenuator test circuit bonded to pitch adapter Beetle 1.3 IT hybrid Slide 16 Use very low number of photons 16 R1=200 R2=10K G=1/50 R1=200 R2=15K G=1/75 R1=200 R2=20K G=1/100 R1=200 R2=30K G=1/150 Slide 17 Inject more photons 17 R1=200 R2=10K G=1/50 R1=200 R2=15K G=1/75 R1=200 R2=20K G=1/100 R1=200 R2=30K G=1/150 Slide 18 Inject more photons, saturation for the highest gain channels sets in 18 R1=200 R2=10K G=1/50 R1=200 R2=15K G=1/75 R1=200 R2=20K G=1/100 R1=200 R2=30K G=1/150 GainDynamic rangeSiPM CH 426 ADC/Pe09 Pe CH 518 ADC/Pe013 Pe CH612 ADC/Pe019 Pe CH78 ADC/Pe028 Pe Slide 19 Outlook (electronics view) Designing new IT hybrids with current divider integrated Designing flex PCB modules for 128CH MPPC modules Characterize electronics performance (noise and dynamic range) Integrating Sci-Fi modules with IT replacement dimensions produced by Aachen PEBS group Further radiation tests Testing shielded box Testing SiPM irradiated by LHCb 19 Slide 20 Radiation hardness The radiation hardness is the big issues regarding the use in high radiation environment. Tests have been performed by Toru Matsumura for the KEK detector collaboration. Whats the degradation? Large increase of the leakage current or dark current or dark noise rate Decrease of the gain For higher dose of irradiation the signal is not present anymore Some numbers: Particle flux at the position of the IT @ nominal LHCb: N charged hadrons (protons) = 3 * 10 2 p / s / mm 2 3 * 10 9 p / year / mm 2 N Rate = 3.2 * 10 2 n / s / mm 2 3.2 * 10 9 n / year / mm 2 D Rate = 480 Gy / year Accumulated doses: 42 Gy and 8.2 Gy for two different detectors 20 Slide 21 21 3 month LHCb Slide 22 Conclusion of irradiation tests performed by Matsumura The irradiation tests show that the current detectors from Hamamatsu (same technology used in the PEBS fibre tracker) can last only order of one month in LHCb environment, detector degradation is already significant. The fact that the SiPMs that should be used for the fiber tracker have smaller surface reduces the dark count by a factor 4 what is seen in the measurements. The shaping time of 25ns reduces the noise count per event also by a factor 2 compared to 50ns shaping time. The increase of the noise level by a factor 10 is still acceptable for this application Some work is done to make the SiPM more radiation hard for similar applications. Have a look at: http://www.nda.ac.jp/cc/radiation/presen/PD07-Matsumura.pdf http://www-conf.kek.jp/PD07/Conference-PD07/timetable.html We need to perform our own tests to understand how far the tracker can still be used due to irradiation. N-irradiation tests in preparation. 22 Slide 23 Scintillating fibre tracker 23