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Published byAbel Townsend Modified over 8 years ago
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Performance of 1600-pixel MPPC for the GLD Calorimeter Readout Jan. 30(Tue.) Korea-Japan Joint Meeting @ Shinshu Univ. Takashi Maeda ( Univ. of Tsukuba) for the GLD Calorimeter Group
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1600-pixel MPPC Guard ring Si Resistor The Multi-Pixel Photon Counter (MPPC) … Novel photon sensor that used for GLD calorimeter readout
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The Multi-Pixel Photon Counter (MPPC) Old Sample Can package 20 improved samples in last October and 400 samples in last December. Very compact plastic package for Beam Test @ DESY 4 mm 1.3 mm 3 mm 1 x 1 mm ---Improved Point--- Higher Gain Lower Noise rate Package becomes compact etc …
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Pulse Shape 1 p.e. 2 p.e.
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Measurement of Basic Characteristics Evaluate 1600-pixel MPPC performance as a function of Bias Voltage and Temperature –Gain, Noise rate, Cross-talk, P.D.E. Set up Thermostatic chamber Blue LEDMPPC
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30 o C 25 o C 20 o C 15 o C 10 o C 0 o C -20 o C Gain S : ADC Sensitivity = 0.25 pC/ADCcount A : Amp gain = 63 e : electron charge = 1.6 x10 -19 C C : Pixel Capacitance V 0 : Breakdown voltage d Pedestal peak 1 p.e. peak 2 p.e. peak
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V 0 with Temperature Variation V 0 is linear to temperature – V = V Bias – V 0 (T) is sensitive to temperature –Most of MPPC performances are affected by temperature change Must be improved V 0 / T = (56.0 ± 0.1) mV/ o C C : Pixel Capacitance V 0 : Breakdown voltage
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Noise Rate Dark noise : Avalanche amplification by thermal electron Noise rate is lower in lower V( = V bias – V 0 ) and temperature 30 o C 25 o C 20 o C 15 o C 10 o C 0 o C -20 o C Threshold 0.5 p.e. 0.5 p.e. Threshold 1.5 p.e. Threshold
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Cross-talk Probability Cross-talk : The cross-talk to adjacent pixels is caused by photons created in an avalanche. 2 pixels fired signals in dark noises are caused by cross-talk Cross-talk probability is not sensitive to temperature change 30 o C 25 o C 20 o C 15 o C 10 o C 0 o C -20 o C
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Photon Detection Efficiency (P.D.E) Q.E. : e - h + pair production probability for single photon injection ( Quantum Efficiency ) Geiger : Avalanche amplification probability from single p.e. geom : Fraction of sensitive region in a sensor ( Geometrical Efficiency) Measurement method Compare # of p.e. of MPPC with # of p.e. of PMT (Reference) MPPC 0.5 mm Pin-hole PMT LED WLSF ~ 16 % ~ Detection probability for single photon injection
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Photon Detection Efficiency 6.3 % uncertainty comes from estimation of PMT’s P.D.E ~ 6.3 % P.D.E. of PMT
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Summary We are evaluating 1600-pixel MPPC characteristic for the GLD calorimeter readout Gain, Noise rate are sufficient for our requirement Breakdown voltage is sensitive to temperature change –Have to monitor the temperature Photon Detection Efficiency is higher than PMT Plans Response curve (Input light-yield vs. Output signal) Evaluate Uniformity in the sensor Measure long-term stability Figure out radiation damage effect and magnetic field stability
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Back up …
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Old sample results - Gain 30 o C 25 o C 20 o C 15 o C 10 o C 0 o C -20 o C a = (5.67 ± 0.03) x10 -2 V/ o C b = 66.2 ± 0.1 V V 0 =aT+b
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Old sample results – Noise rate V bias – V 0 (T) [V] 30 o C 25 o C 20 o C 15 o C 10 o C 0 o C -20 o C
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Old sample results – Cross-talk Cross-talk probability looks stable with temperature in V bias – V 0 < 2.5V. The cross-talk to adjacent pixels is caused by photons created in an avalanche. Cross-talk probability is measured from dark noise rates : ・ 30 ℃ ・ 25 ℃ ・ 20 ℃ ・ 15 ℃ ・ 10 ℃ ・ 0 ℃ ・ - 20 ℃ V bias – V 0 (T) [V]
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Set up Gate Generator Delay Voltage source HV PMT MPPC Stage WLSF Green LED AMP *63 Signal input Gate PC Thermo-static chamber Clock Generator Voltage source
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Light yeild measurement ( with noise and cross-talk subtraction) Measure light yeild of LED light pulse Fit ADC distributon Supposed signals are dominated by Poisson statistics Count number of events below 0.5 p.e. threshold ( both LED on and off ) pedestal Events 0.5 p.e. threshold pedestal Events
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Calculation of Np.e. f(0,μ LED on) = f(0, μ+μ noise ) = f(0,μ) × f(0,μ noise ) f(0,μ) = f(0,μ LED on) / f(0,μ noise ) = e -μ μ = -ln( f(0,μ) ) f(n,μ) is Poisson distribution function μ is Expectated number of Np.e. f(0,μ LED on ), f(0,μ LED off ) are probability of 0 p.e. f(0,μ noise ) = N LED off / N LED off = e -μnoise f(0,μ LED on ) = N LED on / N LED on =e -μLED on pedestal all pedestal all
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Npe MPPC / Npe PMT (Npe ratio)
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WLS Fiber Y-11 Reference : JLC ストリップ・ファイバー電磁カロリメータの性能研究 Katsumi Sekiguchi March. 2003
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QE of H1161GS
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Mean of QE for 1 p.e. QE × relative light yeild on each wave length ∑ ( QE × relative light yeild on each wave length ) = Mean of QE for 1 p.e. ~16.7 %
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Response / Correction curves ( with small cross-talk ) Response curve Correction curve R -1 (p;N fired ) p=0.1 R (p;N pe ) p=0.1 (no cross-talk) p=0
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