1. page 1 of 18 Bjorn S. Nilsen, ALICE November 16 ITS Software meeting ITS Alignment Status Plus other things By Bjørn S. Nilsen The Ohio State University

2. page 2 of 18 Bjorn S. Nilsen, ALICE November 16 ITS Software meeting Outline ● ITS internal Alignment ● Open questions about calibration ● Changes in Tgeant3 and the Virtual MC interface ● Speeding up of SPD simulation ● planned Changes to AliITSgeom ● Conclusions

3. page 3 of 18 Bjorn S. Nilsen, ALICE November 16 ITS Software meeting ITS Alignment ● 2198 Si detector wafers – 240 SPD wafers – 260 SDD wafers – 1698 SSD wafers – X 6 DoF = 13188 DoF ● All of the other Radiation thick Materials of ITS.

4. page 4 of 18 Bjorn S. Nilsen, ALICE November 16 ITS Software meeting Alignment view ● Offline wants new ITS geometry to have “movable” parts. – In principle do-able, but... – Moving part of the ITS geometry leads to overlaps.. – To make remove the modified geometries overlaps, shapes must change (e.g. box->Trap) – This is a problem difficult to solve even in principle. Parts of “Detector response Analysis and Alignment” may be done before “Reconstruction” and may use some of the results from the Tracking and PID.

5. page 5 of 18 Bjorn S. Nilsen, ALICE November 16 ITS Software meeting ITS view (my opinion) ● We align using AliITSgeom (the geometry of our sensitive volumes) – This isn't quite good enough for tracking, the need to know about the material budget between layers – Don't know quite how to solve this. ● Using reconstructed virtual photons converted within the ITS, we can know about all of the material within the ITS – This, along with the corrected AliITSgeom, will be used to rewrite a new ITS geometry (up to some possible limits to be determined)

6. page 6 of 18 Bjorn S. Nilsen, ALICE November 16 ITS Software meeting Alignment Status ● new AliITSAlignRecPoint (derived from AliITSRecpoint) – Adding data members needed for Alignment (Event#, Det#, Global coordinate,...) – Adding functionality, not found in AliITSRecPoint ● new memory resident array classes for AliITSAlignRecPoint (by detector, track,...) ● More still to come Work just starting up again (see ITS TDR for original results)

7. page 7 of 18 Bjorn S. Nilsen, ALICE November 16 ITS Software meeting Calibration ● We had a long and active meeting about calibration at the last Offline week. – Offline want to know, from us(?) ● What data will be stored in the different data bases ● What data “we” need for the Offline ● And where all of this data can be found. – Offline presented a prototype “framework” to get access to information kept in ALICE data bases ● Prototype only worked with DCS data base ● Most ITS information “we” need is not in DCS data base ● “User” interface very poor – must give an ascii input file with a list of all data possibly wanted – ascii file must also contain address of data base – format of ascii file dependent on which data base accessing ● Seems as cumbersome as accessing data bases directly – Aren't there supposed to be API's for all Data Bases? – Isn't there ROOT interfaces to all of these Data Bases?

8. page 8 of 18 Bjorn S. Nilsen, ALICE November 16 ITS Software meeting Process to Get Calibration Data Peter Chochula Boyko Yordanov

9. page 9 of 18 Bjorn S. Nilsen, ALICE November 16 ITS Software meeting Calibration Information Whole ITS Incomplete Preliminary ● Cooling: Air (flow rate, humidity, Temperature), Water Cooling {1/half-Barrel (Flow meter, Waist Oxygen Levels), 26 each side (Cooing circuit on/off, Temperature, Pressure)}, 2 Phase (?) ● ITS Alignment monitoring System: ● Racks: ? ● Inter Lock: ? ● ? ● Geometry, Survey (not in any data base, Alice Note?) Simulation Reconstruction

10. page 10 of 18 Bjorn S. Nilsen, ALICE November 16 ITS Software meeting Calibration Information SPD Incomplete Preliminary ● 10 Sectors, 6 Staves/sector, 4 detectors/Stave, 5 readout chips/detector, 256×32 pixels/readout chip ● ? ● Dead pixels/readout chips/Staves, Noisy pixels, Geometry ● Noise levels, Thresholds, Temperature, Bias voltage, Geometry Simulation Reconstruction

11. page 11 of 18 Bjorn S. Nilsen, ALICE November 16 ITS Software meeting Calibration Information SDD Incomplete Preliminary ● 22 [14] ladders/layer, 2 sets of ladder end boards/ladder, 8 [6] detectors/ladder, 2 hybrids/detector 3 Ambra+Pascal/hybrid, 256 Anodes/hybrid ● Power supply, low voltage, medium voltage, high voltage ● Hybrid: Temperature, over current, voltage setting, readout frequency, ● CARLOS: low & high thresholds, enable/disable zero suppression ● ? ● High & low thresholds, baseline, noise level, temperature (injectors), Geometry ● Correction maps (?) Simulation Reconstruction

12. page 12 of 18 Bjorn S. Nilsen, ALICE November 16 ITS Software meeting Calibration Information SSD Incomplete Preliminary ● 2 Layers, 33 [33] ladders/layer, 25 [22] detectors/ladder, 2 hybrids/detector, 768 strips/hybrid ● ? ● Threshold, Baseline, noise level, temperature, bias voltage, Geometry Simulation Reconstruction

13. page 13 of 18 Bjorn S. Nilsen, ALICE November 16 ITS Software meeting Calibration Sources (?) Incomplete Preliminary ● Detector Construction Data base – Detector & other positions, ● Special data and none data runs (after some analysis) – noise, temperature,... ● Regular data runs, calibration event (after some analysis) – temperature (injector events),... ● Data runs, real data (after some analysis) – noise (zero non-suppressed data), alignment,...

14. page 14 of 18 Bjorn S. Nilsen, ALICE November 16 ITS Software meeting TGeant3 and AliITSgeom initialization Changes to TGeant3, TGeant3TGeo..., and TVirtualMC. ● Added function, GetTransformation, GetShape, GetMaterial, & GetMedium ● Now we can remove the use of TGeant3 functions ● This will now allow all of our geometries to be use with Geant3 (native/TGeo), Geant4, and Fluka (except for the use of MANY) ● Waiting for, Update of Geant3, ROOT, and OK from Peter

15. page 15 of 18 Bjorn S. Nilsen, ALICE November 16 ITS Software meeting SPD Simulation dubna Updates, to come Presently 1Trapezoidal Integration along track path between hits. -Easy to code & debug -Inefficient 2Step size is of the order 1µm -Much smaller than needed -Guarantees accuracy 34 evaluations of Tmath::Erfc -~exp(8 th order polynomial) 4Loop over ±3 (x), ±2 (z) pixels Under Development 1AGaussian Integration along track path between hits. -Very efficient -Many fewer steps (~10 compared to ~200) -Require 4 evaluations of Erfc functions 1BAnd/Or Analytic Integration -Must be done via an expansion -Includes evaluation of Erfc functions 2Loop over ±3 (x), ±2 (z) pixels Max -Only as needed 3More general algorithm -Applicable to SPD and SSD -May be expendable to SDD

16. page 16 of 18 Bjorn S. Nilsen, ALICE November 16 ITS Software meeting ● All parameters will be unchanged – Work on optimizing parameters can use existing code – Only algorithm will change ● Code ready by End of November ● Code tested by End of December – Comparison of SDigits between versions – Require same numbers up to ± 1 electron or better SPD Simulation dubna Updates, to come

17. page 17 of 18 Bjorn S. Nilsen, ALICE November 16 ITS Software meeting Changes to AliITSgeom ● Allow it to work with the “new” tracking standard detector local coordinate system (see presentation by Juira) ● Give AliITSgeom direct access, if not complete ownership of, the segmentation class – AliITSgeom would then do transformation from module index coordinates through ALICE global coordinates. – With one call/function one can go from any set of coordinates to any other.

18. page 18 of 18 Bjorn S. Nilsen, ALICE November 16 ITS Software meeting Conclusions ● ITS internal Alignment work started ● Open questions about calibration ????????? help! ● Changes in TGeant3 and the Virtual MC interface ready to be put to use ● Speeding up of SPD simulation coming soon ● planned Changes to AliITSgeom coming soon