I. Time Resolution of a MCP-PMT and II. Test Infrastructure in the - PowerPoint PPT Presentation

I. Time Resolution of a MCP-PMT and II. Test Infrastructure in the Solid State Detector Lab M. Centis Vignali 1 Representing: CEA (Saclay), CERN, NSRC “Demokritos”, Princeton University, Thessaloniki University, USTC (Hefei) 22.02.2017 RD51 Precise Timing Workshop, CERN 1 matteo.centis.vignali@cern.ch 1 / 28

The RD51 PICOSEC collaboration Fast Timing for High-Rate Environments: A Micromegas Solution Institutes: CEA (Saclay) : T. Papaevangelou, I. Giomataris, M. Kebbiri CERN : L. Ropelewski, E. Oliveri, F . Resnati, R. Veenhof, S. White, H. Muller, F . Brunbauer, J. Bortfeldt, M. van Stenis, M. Lupberger, T. Schneider, C. David, D. Gonzalez Diaz 2 NCSR Demokritos : G. Fanourakis Princeton University : S. White, K.T. McDonald, Changguo Lu University of Thessaloniki : S. Tzamarias University of Science and Technology of China : Yi Zhou, Zhiyong Zhang, Jianbei Liu Contributing from the RD50 collaboration: CERN : M. Centis Vignali, M. Moll, and the SSD lab group (EP-DT-DD) 2Present Institute: University of Santiago de Compostela 2 / 28

I. Time Resolution of a MCP-PMT 3 / 28

Timing σ 2 ∆ t = σ 2 t 1 + σ 2 σ 2 t = σ 2 J + σ 2 ∆ t = t 2 − t 1 TW + ... t 2 Jitter Time walk The noise influences the time at Variations in the amplitude which the threshold is crossed influence the time at which the σ J = σ n / dV threshold is crossed dt Countermeasures: Countermeasures: Algorithm e.g. CFD Reduce rise time Improve noise figure 4 / 28

MCP-PMT Microchannel plate photomultipliers MPC as amplification structure Million of microglass Hamamatsu PMT handbook, chapter 10 tubes fused in parallel 1 − 3 plates in one PMT Channel diameter 6-20 µ m V bias ≈ 3000 V Gain 10 4 − 10 6 5 / 28

Beam Test Performed by the PICOSEC group of the RD51 collaboration CERN SPS Fall 2016 Several timing detectors Gas detectors Silicon detectors MCP-PMT used as time reference Analysis of a special run to characterize the timing reference 6 / 28

Beam Test Setup 150 GeV/c muons 2 MCP-PMTs ( ˇ C light) Scope readout Trigger on PMT2 (50 mV thr) MCP-PMTs Hamamatsu R3809U-50/52 3.2 mm quartz window Amplitude [V] 11 mm diameter photocathode 0.4 0.3 Bias 2.8 kV 0.2 Gain ≈ 8 · 10 4 0.1 Scope 0 × − 9 10 − − − − 2 1.5 1 0.5 0 0.5 1 1.5 2 2.5 GHz bandwidth Time [s] 8 bit (LSB 3.5 mV) Thanks to Stefano Mazzoni for lending one of the MCP-PMT 40 GSa/s (25 ps sampling) 7 / 28

Noise and Baseline Noise Baseline Distr of all points with time < -2 ns Mean (evt by evt) of all points with ≈ 1.6 mV for both PMTs time < -2 ns PMT1 PMT1 4 10 6 10 3 10 5 10 2 10 10 4 10 3 10 1 − − − − − − − − 0.02 0.015 0.01 0.005 0 0.005 0.01 0.015 0.02 0.004 0.003 0.002 0.001 0 0.001 0.002 0.003 0.004 Amplitude [V] Baseline [V] Amplitude [V] 0.4 0.3 0.2 0.1 0 × − 9 10 − − − 6 4 2 0 2 4 6 Time [s] 8 / 28

Event Selection From run using a 5 × 5 mm 2 Max ampli distribution trigger scintillator: PMT1, PMT2 Max ampli 1 > 200 mV 4 10 Max ampli 2 > 120 mV 3 10 Max using parabolic 2 10 interpolation 10 Max measured from baseline 1 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 Amplitude [V] Amplitude [V] Components: 0.4 Poisson distribution of number of 0.3 0.2 photoelectrons 0.1 Partial collection of ˇ C light 0 − × 9 10 − − − 6 4 2 0 2 4 6 Time [s] 9 / 28

Data Interpolation Signal sampled every 25 ps Linear interpolation of 2 points to determine crossing time 10 / 28

Rise Time 20% 80% Correlation rise time amplitude PMT1 Average rise time 116 ps (no amplitude cuts) PMT1, PMT2 − × 9 10 1 Rise time [s] 6000 0.9 5000 5000 0.8 4000 0.7 4000 0.6 3000 0.5 3000 0.4 2000 2000 0.3 0.2 1000 1000 0.1 − × 9 10 0 0 0 0 0.02 0.04 0.06 0.08 0.1 0.12 0.14 0.16 0.18 0.2 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 Rise time [s] Amplitude [V] Same rise time for both PMTs Rise time independent of amplitude Amplitude [V] 0.4 0.3 0.2 0.1 0 − × 9 10 − − − 6 4 2 0 2 4 6 Time [s] 11 / 28

Timing using Leading Edge Discriminator Resolution → std dev of ∆ t = t 2 − t 1 Resolution map Diagonal of the 2d plot × − 12 × − 10 12 10 0.11 38 Thr 2 [V] t [s] t [s] 0.1 35 ∆ ∆ 36 Std Dev Std Dev 0.09 30 34 0.08 25 0.07 32 20 0.06 30 0.05 15 0.04 28 10 0.03 26 5 0.02 0.01 0 0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.08 0.09 0.1 0.11 0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.08 0.09 0.1 0.11 Thr 1 [V] Thr [V] ∆ t distribution, thr = 30 mV Max ampli at least 5% higher σ σ ± ± = 24.02 = 24.02 0.30 ps, 9855 events 0.30 ps, 9855 events than thr 600 500 400 300 200 100 × − 9 10 0 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 ∆ t [s] 12 / 28

Timing using Constant Fraction Discriminator Resolution → std dev of ∆ t = t 2 − t 1 Resolution map Diagonal of the 2d plot × − 12 × − 10 12 10 CFD frac 2 t [s] t [s] 24 0.9 14 ∆ ∆ Std Dev Std Dev 0.8 22 12 0.7 20 10 0.6 18 8 0.5 16 0.4 6 14 0.3 4 12 0.2 10 2 0.1 8 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 CFD frac 1 CFD frac ∆ t distribution, CF = 0.45 Reduction of time walk σ σ ± ± = 7.66 = 7.66 0.22 ps, 9855 events 0.22 ps, 9855 events 2000 1800 1600 1400 1200 1000 800 600 400 200 × − 9 10 0 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 ∆ t [s] 13 / 28

Timing as a Function of Amplitude Resolution → std dev of ∆ t = t 2 − t 1 Resolution map Diagonal of the 2d plot − × 12 × − 10 10 12 0.8 20 20 Amplitude 2 [V] t [s] t [s] 18 18 0.7 ∆ ∆ Std Dev Std Dev 16 16 0.6 14 14 0.5 12 12 0.4 10 10 8 8 0.3 6 6 0.2 4 4 0.1 2 2 0 0 0 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 Amplitude 1 [V] Amplitude [V] CFD with CF = 0.45 The resolution improves with amplitude No amplitude cuts “Holes” due to low statistics 14 / 28

Transit Time Spread for MCP-PMT √ σ TTS ∝ TTS / N N → number of photoelectrons � ⇒ σ TTS N 1 + 1 1 ∝ ∆ t N 2 Conversion coeff to number of photons from a different run × − 12 10 20 t [s] 18 ∆ Std Dev 16 14 12 10 8 6 4 Variations in the time it takes for an 2 0 electron to move from the 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1/N1 + 1/N2 photocathode to the MCP Outliers probably due to low statistics 15 / 28

Leading Edge Interpolation Linear interpolation of points between 20% and 80% of ampli LED thr = 30 mV CFD CF = 0.45 σ σ ± ± σ σ ± ± = 13.61 = 13.61 0.21 ps, 9855 events 0.21 ps, 9855 events = 7.78 = 7.78 0.22 ps, 9855 events 0.22 ps, 9855 events 1000 2000 1800 800 1600 1400 600 1200 1000 400 800 600 200 400 200 × − − 9 × 9 10 10 0 0 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 ∆ t [s] ∆ t [s] Std dev 2 pt interpolation: 24.0 ps Std dev 2 pt interpolation: 7.7 ps LED more affected than CFD due to different thr 16 / 28

Leading Edge Interpolation Linear interpolation of points between 20% and 80% of ampli LED thr = 30 mV Extrapolation to 0 of interpolation σ σ ± ± = 13.61 = 13.61 0.21 ps, 9855 events 0.21 ps, 9855 events σ σ ± ± = 9.73 = 9.73 0.38 ps, 9855 events 0.38 ps, 9855 events 1000 1800 1600 800 1400 1200 600 1000 400 800 600 200 400 200 × − 9 10 − 0 × 9 10 0 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 ∆ 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 t [s] ∆ t [s] Std dev 2 pt interpolation: 24.0 ps Improvement wrt LED due to partial time walk correction 17 / 28

II. Test Infrastructure in the Solid State Detector Lab 18 / 28

Silicon Detectors Solid state ionization detector Mono-crystalline Si Rectifying junction in reverse bias Mean ionization energy: 3.6 eV/eh Typical thickness, 300 µ m typical Signal ≈ 24000 e − in 300 µ m Fast signals, O(10 ns) 19 / 28

Transient Current Technique (TCT) Measure i ( t ) to investigate sensor’s electric field and charge collection i ind = n · q 0 · v · E W = nq 0 µ E E W = 1 / d v = µ · E d Produce eh pairs using a pulsed laser Red laser → short absorption depth (few µ m) → one type of charge carriers drifts Infrared laser → long absorption depth ( ≈ mm) → similar to charged particle signal Read out the signal using an oscilloscope 20 / 28

TCT Example (Non-irradiated Diode) Holes drift (red top) Electrons drift (red bottom) 21 / 28

Edge TCT Drift velocity profile for an irradiated detector ( Φ eq = 5 · 10 15 cm − 2 ) In irradiated sensors trapping of e/h reduces the signal during drift → less signal to study the E field Edge illumination Use the first part of the i ( t ) pulse to extract information Scan the sensor thickness by moving the laser spot From: Investigation of Irradiated Silicon Detectors by Edge-TCT, G. Kramberger et al., IEEE 2010 22 / 28

TCT setup Red (600 nm) and infrared (1064 nm) laser 200 ps pulse Laser focus ≈ 10 µ m Front, back, and edge illumination Current amplifier 2.5 GHz, 20 GSa/s oscilloscope Reference diodes to monitor laser intensity Temperature control Translation stages 23 / 28