The CBM sensor digitizer

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1 The CBM sensor digitizer C.Dritsa IKF-Frankfurt, IPHC-Strasbourg (now at JLU Giessen) C.Dritsa, St.Odile, 08 September

2 Outline Motivation Model requirements Description of the model Important definitions (1) charge generation charge sharing Evaluation Important definitions (2) Comparison with experimental data Outlook C.Dritsa, St.Odile, 08 September

3 Motivation Digitizer model developed in order to allow simulating the CBM-MVD. In collaboration with the IPHC-PICSEL group in Strasbourg and the IKF-MVD group in Frankfurt. It was inspired by a detector response model developed for the ILC vertex tracker M. Battaglia, Response simulation of CMOS pixel sensors for the ILC vertex tracker, Nuclear Instruments and Methods in Physics Research A 572 (2007) C.Dritsa, St.Odile, 08 September

4 CBM-MVD response model requirements Realistic simulations allowing to simulate: Cluster properties: size, shape pixel size vary number of ADC channels of the readout particles impinging with high incident angles noise, fake hits Rapid simulation features simulate collision pile up delta electrons (of concern in CBM) fast, allowing high statistics simulations C.Dritsa, St.Odile, 08 September

5 Challenge: Spirit of the model Charge carrier transport process too complex and slow for simulation Solution: Parameterization of the sensor response Use experimental data GEANT provides only entry and exit coordinates of the particle in the volume no de/dx from GEANT C.Dritsa, St.Odile, 08 September

6 Reference data Data acquired at CERN/SPS with pions 120 GeV/c Sensor under test: MIMOSA17 AMS 0.35 standard low resistivity epitaxial layer analogue output (12 bit charge resolution) 30 µm pixel pitch Particle incident angles 0-75 degrees (90 degrees is parallel to the sensor plane) C.Dritsa, St.Odile, 08 September

7 The digitizer C.Dritsa, St.Odile, 08 September

8 MPV Important definitions (1) Q i 0 Q i Landau Lorentz C.Dritsa, St.Odile, 08 September

9 Other features Simulated by random sampling of a distribution following a Gauss law with adjustable µ, σ mean=0 σ =15 electrons Number of ADC bits adjustable 12 bits Pixel pitch adjustable 30 µm C.Dritsa, St.Odile, 08 September

10 The model: Input Landau: Accumulated charge on 25 pixels The charge of the cluster is taken by random sampling of the experimental distribution for 25 pixels 0 degrees incident angle The simulation of inclined particles is derived by this initial parameterization. The charge distribution among the pixels in the cluster is based on a 2D Lorentz distribution (derived from the 1D) 0 degrees incident angle C.Dritsa, St.Odile, 08 September

11 The model: charge generation Q 0,l 0 Q incl, l incl Q incl Q 0 l incl l 0 Q 0, l 0 : known l incl : provided by GEANT C.Dritsa, St.Odile, 08 September

12 The model: charge distribution Illustration for inclined track Charge provided by Landau (25 pixels) The trajectory is divided in segments A Lorentz function corresponds to each segment C.Dritsa, St.Odile, 08 September

13 The model Charge on pixel i x,y-coordinates of segment k L(x k,i,y k,i ) Lorentz Amplitude Lorentz width Sum over segments (k) x,y-coordinates of pixel i Pixel pitch C.Dritsa, St.Odile, 08 September

14 Evaluation C.Dritsa, St.Odile, 08 September

15 Accumulated charge (MPV) Important definitions (2) Q1>Q2>Q3 Accumulated charge plot Q1 Qi<0 (i~n) Q1 Q2 Q3 Qi Q1+Q2 Q1+Q2+Q3 Q1+Q2+ +Qi N Number of Pixels The accumulated charge plot describes the charge sharing among the pixels of the cluster: e.g. the seed pixel collects ~30% of the total cluster charge. C.Dritsa, St.Odile, 08 September

16 Evaluation: MPV of Landau C.Dritsa, St.Odile, 08 September

17 Evaluation: sigma of Landau C.Dritsa, St.Odile, 08 September

18 Evaluation Average number of pixels/cluster C.Dritsa, St.Odile, 08 September

19 Evaluation: shape Simulation Experimental data C.Dritsa, St.Odile, 08 September

20 Summary and outlook Digitizer model developed for the CBM- MVD and successfully tested with experimental data. Model was successfully tested on High- Resistivity sensors (M.Domachowski) Successfully tested on neutron irradiated sensors (M.Domachowski) Simulation of MIMOSA-26 data sparcification in process (Q.Li) C.Dritsa, St.Odile, 08 September

21 Acknowledgments Thanks to: the IPHC-PICSEL group and the IKF-MVD group. In particular: IPHC: J.Baudot, M.Goffe, R.DeMasi, M.Winter IKF: M.Deveaux, M.Domachowski, Q.Li, J.Stroth C.Dritsa, St.Odile, 08 September

22 Backup C.Dritsa, St.Odile, 08 September

23 Accumulated charge [e - ] High-Res MAPS: Measurement vs. simulation Melissa Domachowski Number of pixels Measurement Simulation Simulation of HR-MAPS with the MVD-digitiser: OK Simulation of irradiated MAPS: OK C.Dritsa, St.Odile, 08 September Simulation of irradiated MAPS in CBM-Root Melissa Domachowski - CBM Collaboration Meeting, Dresden 2011

24 Particle yields C.Dritsa, St.Odile, 08 September

Charged particle detection performances of CMOS Pixel Sensors designed in a 0.18 µm CMOS process based on a high resistivity epitaxial layer

Charged particle detection performances of CMOS Pixel Sensors designed in a 0.18 µm CMOS process based on a high resistivity epitaxial layer Jérôme Baudot on behalf of the PICSEL team of IPHC-Strasbourg