Commissioning of the Silicon Drift Detector of the ALICE experiment at the LHC

Transcription

1 Silicon Drift Detector of ALICE Commissioning of the Silicon Drift Detector of the ALICE experiment at the LHC Emanuele Biolcati for ALICE collaboration Dipartimento di Fisica dell Università di Torino INFN Torino XLVII International Winter Meeting on Nuclear Physics Bormio - Jan , Emanuele Biolcati Commissioning of the ALICE Silicon Drift Detector

2 Outlines Silicon Drift Detector of ALICE Detector Physics 1 Silicon Drift Detector of ALICE Detector Physics 2 Front-end electronics: noise and gain SDD parameter: drift speed SDD response: charge collection 3 2 Emanuele Biolcati Commissioning of the ALICE Silicon Drift Detector

3 Silicon Drift Detector of ALICE ALICE LHC Detector Physics 3 Emanuele Biolcati Commissioning of the ALICE Silicon Drift Detector

4 Silicon Drift Detector of ALICE Detector Physics Pb-Pb LHC (simulation) 4 Emanuele Biolcati Commissioning of the ALICE Silicon Drift Detector

5 Silicon Drift Detector of ALICE The Inner Tracking System Detector Physics Pixel (SPD) 240 sensitive volumes Drift (SDD) 260 sensitive volumes Strip double-side (SSD) 1698 sensitive volumes Resolution Detector x loc [µm] z loc [µm] occupancy [%] SPD SDD SSD Emanuele Biolcati Commissioning of the ALICE Silicon Drift Detector

6 Silicon Drift Detector of ALICE ALICE Silicon Drift Detector Detector Physics Anodes Cathodes Anode pitch 294 µm Cathode pitch 120 µm HV (nominal) V 6 Emanuele Biolcati Commissioning of the ALICE Silicon Drift Detector

7 Silicon Drift Detector of ALICE ALICE Silicon Drift Detector Detector Physics Anodes Cathodes Anode pitch 294 µm Cathode pitch 120 µm HV (nominal) V 6 Emanuele Biolcati Commissioning of the ALICE Silicon Drift Detector

8 Silicon Drift Detector of ALICE Detector Physics The SDD module front 7 back Emanuele Biolcati Commissioning of the ALICE Silicon Drift Detector

9 Silicon Drift Detector of ALICE The SDDs inside the ITS Detector Physics 8 Emanuele Biolcati Commissioning of the ALICE Silicon Drift Detector

10 Silicon Drift Detector of ALICE Physical motivations of ITS (I) Detector Physics Primary vertex reconstruction Secondary vertex reconstruction Track impact parameter 9 Emanuele Biolcati Commissioning of the ALICE Silicon Drift Detector

11 Silicon Drift Detector of ALICE Physical motivations of ITS (II) Detector Physics Complement TPC tracking Standalone tracking 10 Emanuele Biolcati Commissioning of the ALICE Silicon Drift Detector

12 Outlines Silicon Drift Detector of ALICE Front-end electronics: noise and gain SDD parameter: drift speed SDD response: charge collection 1 Silicon Drift Detector of ALICE Detector Physics 2 Front-end electronics: noise and gain SDD parameter: drift speed SDD response: charge collection 3 11 Emanuele Biolcati Commissioning of the ALICE Silicon Drift Detector

13 Baseline and noise Silicon Drift Detector of ALICE Front-end electronics: noise and gain SDD parameter: drift speed SDD response: charge collection 4 readout chips per SDD semi-module different response function for each chip equalization of the baseline calculation of noise per anode (133k) extimation of the common mode noise tag of good/bad anodes 12 Emanuele Biolcati Commissioning of the ALICE Silicon Drift Detector

14 Silicon Drift Detector of ALICE Baseline and noise distribution Front-end electronics: noise and gain SDD parameter: drift speed SDD response: charge collection run results baseline equalized to 20 ADC raw noise 2.3 ADC signal peak by a MIP (close to the anodes) 120 ADC w/o common mode noise 1.9 ADC good anodes 99.5% 13 Emanuele Biolcati Commissioning of the ALICE Silicon Drift Detector

15 Silicon Drift Detector of ALICE Front-end electronics: noise and gain SDD parameter: drift speed SDD response: charge collection Baseline and noise stability (during cosmic runs of 2008) 14 Emanuele Biolcati Commissioning of the ALICE Silicon Drift Detector

16 Gain measurement Silicon Drift Detector of ALICE Front-end electronics: noise and gain SDD parameter: drift speed SDD response: charge collection test pulse = signal self-generated by the amplifier measurement of the gain of the amplification chain 15 Emanuele Biolcati Commissioning of the ALICE Silicon Drift Detector

17 Silicon Drift Detector of ALICE Front-end electronics: noise and gain SDD parameter: drift speed SDD response: charge collection Gain stability (during cosmic runs of 2008) gain 1.28 ADC/DAC variation due to a change of the ADC sampling rate (from 40 MHz to 20 MHz) 16 Emanuele Biolcati Commissioning of the ALICE Silicon Drift Detector

18 Silicon Drift Detector of ALICE The importance of the drift speed Front-end electronics: noise and gain SDD parameter: drift speed SDD response: charge collection { vdrift = µ e E µ e T (K) 2.4 ALICE SDD requirement: σ x 40µm drift speed very sensitive to temperature variations need to measure (frequently) the drift speed value in many positions of the sensitive region of the detector 17 Emanuele Biolcati Commissioning of the ALICE Silicon Drift Detector

19 Silicon Drift Detector of ALICE Drift speed calculation Front-end electronics: noise and gain SDD parameter: drift speed SDD response: charge collection 3 rows of 33 MOS injectors per semi-module drift speed calculated in 33 positions (from linear fit of 3 points) distribution vs anode position reflects temperature effects 18 Emanuele Biolcati Commissioning of the ALICE Silicon Drift Detector

20 Silicon Drift Detector of ALICE Drift speed vs module Front-end electronics: noise and gain SDD parameter: drift speed SDD response: charge collection 19 Emanuele Biolcati Commissioning of the ALICE Silicon Drift Detector

21 Drift speed vs time Silicon Drift Detector of ALICE Front-end electronics: noise and gain SDD parameter: drift speed SDD response: charge collection 20 Emanuele Biolcati Commissioning of the ALICE Silicon Drift Detector

22 Silicon Drift Detector of ALICE Front-end electronics: noise and gain SDD parameter: drift speed SDD response: charge collection Reconstruction of a cosmic ray in the ITS before calibration after calibration Cosmic charge cluster 21 Emanuele Biolcati Commissioning of the ALICE Silicon Drift Detector

23 Silicon Drift Detector of ALICE Charge distribution in SDD Front-end electronics: noise and gain SDD parameter: drift speed SDD response: charge collection Cluster distribution from cosmic tracks (fitted with a convolution of Landau+Gaussian) 22 Emanuele Biolcati Commissioning of the ALICE Silicon Drift Detector

24 Data vs simulation Silicon Drift Detector of ALICE Front-end electronics: noise and gain SDD parameter: drift speed SDD response: charge collection most probable value for energy deposition of a MIP in 300 µm of silicon conversion factor from ADC units to kev 23 Emanuele Biolcati Commissioning of the ALICE Silicon Drift Detector

25 Silicon Drift Detector of ALICE Charge vs drift distance Front-end electronics: noise and gain SDD parameter: drift speed SDD response: charge collection dependence on the distance between impact point and the collection anodes possible reasons: traps in Silicon, signal tails cut by threshold offline correction of the measured charge value 24 Emanuele Biolcati Commissioning of the ALICE Silicon Drift Detector

26 Silicon Drift Detector of ALICE Front-end electronics: noise and gain SDD parameter: drift speed SDD response: charge collection Charge vs drif distance: data and simulation 25 Emanuele Biolcati Commissioning of the ALICE Silicon Drift Detector

27 Offline correction Silicon Drift Detector of ALICE Front-end electronics: noise and gain SDD parameter: drift speed SDD response: charge collection 26 Emanuele Biolcati Commissioning of the ALICE Silicon Drift Detector

28 Outlines Silicon Drift Detector of ALICE 1 Silicon Drift Detector of ALICE Detector Physics 2 Front-end electronics: noise and gain SDD parameter: drift speed SDD response: charge collection 3 27 Emanuele Biolcati Commissioning of the ALICE Silicon Drift Detector

29 Silicon Drift Detector of ALICE Commissioning results 97.6% of SDD modules in acquisition (in 2008) Detector calibration parameters stable and stored automatically after each calibration run in the ALICE calibration database: noise gain drift speed (temperature) Charge conversion factor fine tuned and charge dependence on drift lenght corrected SDDs are ready for p p collisions 28 Emanuele Biolcati Commissioning of the ALICE Silicon Drift Detector

30 Ready to go Silicon Drift Detector of ALICE Z-φ raw occupancy from particles generated by LHC beam dump (September 2008) 29 Emanuele Biolcati Commissioning of the ALICE Silicon Drift Detector

31 That s all, thanks. 30 Emanuele Biolcati Commissioning of the ALICE Silicon Drift Detector

32 Backup Extra slides 31 Emanuele Biolcati Commissioning of the ALICE Silicon Drift Detector

33 files in the OCDB CalibSDD contains: baselines, noise and gain for each anode flag for bad module, bad chip, bad anode flag for zero suppression and sampling frequency updated: by the preprocessor after each PEDESTAL+PULSER runs RespSDD contains: time offset, conversion factor ADC kev updated: after offline analysis of reconstructed points DriftSpeedSDD contains: drift speed (parametrized) vs anode number updated: by the preprocessor after each INJECTOR run 32 Emanuele Biolcati Commissioning of the ALICE Silicon Drift Detector

34 Temperature vs module { ( ) 1 vdrift = µ e E vdrift 2.4 /E µ e T (K) 2.4 T (K) = µ e (293K) 33 Emanuele Biolcati Commissioning of the ALICE Silicon Drift Detector

35 Noise of common mode 34 Emanuele Biolcati Commissioning of the ALICE Silicon Drift Detector

36 Charge vs drift lenght 35 Emanuele Biolcati Commissioning of the ALICE Silicon Drift Detector

37 Time zero: residuals method 36 Emanuele Biolcati Commissioning of the ALICE Silicon Drift Detector

38 Time zero extraction methods 1. Minimum drift time how: extraction from time distribution of all the measured clusters why: no need to use calibration quantities, no need to use information from other layers why not: large statistics of RecPoints required 2. Track cluster residuals how: extracted by exploiting the opposite sign of residuals in the two detector sides why: requires less statistics required why not: requires use of drift speed and correction maps, requires track reconstruction in the SPD or SSD 37 Emanuele Biolcati Commissioning of the ALICE Silicon Drift Detector

39 Time zero: simulation and data Simulation the results are consistent Data method 1 is not applicable method 2 gives incoherence under investigation 38 Emanuele Biolcati Commissioning of the ALICE Silicon Drift Detector

40 Doping inhomogeneities Array of 520 AliITSMapSDD objects systematic deviations on the drift time coordinate of the reconstructed points 39 Emanuele Biolcati Commissioning of the ALICE Silicon Drift Detector