TileCal EM scale status Irene Vichou University of Illinois at Urbana on behalf of TileCal Collaboration MPI Hadronic Calibration Workshop May 3 rd, 2006

2 The TileCal detector A TileCal Module 64 Barrel 2x64 Ext. Barrel tiles fibre Finger LVPS Electronics Drawer

3 TileCal RO elements scheme Mixe r Tile/Fibre PMT Divider 3-in-1 Analog Digital Optical Link Interface ADC Integrator Adder Digitizer HVOpto HV Micro CANbus 7  probes DC Calibrations TTC µ Trigger Hadron Trigger Mother Board Bus Board L H Energy LVPS 3 5 Bulk LVPS Bulk HVPS ROD Cs calibration Laser calibration/LED CIS calibration The calibrations tools follow different paths (with partial overlap)

4 CIS: Change in ADC/pC from between July and October in one module Variations < 0.5% Typical channel-to-channel variation in a modules have rms/mean ~ 1.5%, for which we are correcting. M.Hurwitz

5 3 tile rows 6 tile rows 2 tile rows 3 tile rows 4 tile rows Each TileCal cell consist in depth of N (2,3,4,6) tile row segments. The Cs source passes through them all (11 in total) Tile Row Segment

6 Cell structure and comments In the HV equalisation procedure (with Cs data): 1. and 3.(partially) are compensated for. 2. remain 4. is not felt by the Cs 1.Cell to cell fluctuations, due to different scintillators quality have been taken care of during the construction for better uniformity. 2.Tile to tile fluctuations in a cell mainly due to the optics instrumentation effects. 3.Tile row to tile row in a cell fluctuations Residual non-uniformity due to tile size, fibers layout. 4.Parabola shape response vs y (phi) for the tiles. D.Lawlor

7 Cs in a cell Individual tile/fiber Tile row segment in a cell (line) Unfolded individual tile/fiber Response (point) The average of the 3 lines is the measure of the response of the cell for Cs. The precision for a cell response is ~1% Cs team- Protvino Tile-to-tile and tile-rows-in-a cell fluctuations

8 Equalisation of cells with Cs The Cs response is set to give on avg. 1.1 pCb/GeV (fit method), or 1.2 (for 90deg flat filter, historical). An iterative procedure equalises all the channels responses by setting the HV. Uses info from one row or the avg. of all rows in a TileCal cell Uniformity of settings reflects the intrinsic calorimeter non-uniformity. The reproducibility of the system has been proved to be ~0.2%

9 Particles calibration in testbeam Testbeam calibration of 12% of the modules, exposed to electrons, muons (projective, 20deg, 90 deg) has been performed. NB. The 90deg are the only ones that “see” the tile row fluctuations. The EM scale factors now being used come from the e runs at 20deg mainly (e at 90deg also looked). Only border cells calibrated The muon at 90deg are very useful to correlate with Cs and they “see” all tile rows and all cells.

10 Electrons calibration at 20 deg The rms over the cells calibrated is 3.1%. The shift between the two methods is just a factor. Mean of the calibrated modules Those two cases have bad run conditions (investigating) Y.Kultchitsky

11 Distribution of the EM scale factors/cell for the three instrumentation families. The rms reflects the choises of distributing the tiles wrt to their light yield IFA: best uniformity JINR: good uniformity and also optimisation of sorting ANL: worse uniformity Y.Kultchitsky EBA EBC BARREL

12 Electrons at 90 deg EM Scale factors using One cell of each sampling (side) RMS: 4.2% Investigating possible improvement looking at the Cs data for tile rows for those modules. Y.Kultchitsky

13 Muons at 90deg Rms: 2.0% Rms: 1.6% Muon signal/TileRow period before and after taking into account the Cs row-to-row variations. The rms of the muon signals in all tile row segments of many modules over many testbeam periods is 4.3% The cell muon response for the same sample has an rms of 2.7%. This can be considered as the limit from the Cs equalisation procedure during the standalone testbeam periods. Oriol,Ilya -IFAE

14 Uniformity for pions 180 GeV over different modules (pC) from calibration tests Concentrated on |η|=0.35 and |η|=0.45 Combined η>0 and η<0 points to have a total of 10 points for 10 different modules in 6 different run periods RMS/Mean (|η|=0.45) is 1.32% RMS/Mean (|η|=0.35) is 1.14% M.Hurwitz

15 Finishing… The EM scale factors in the 12% of the modules we have tested show an rms of 3~4% In a module the EM scale from the edge cells can be propagated: Using the Cs equalisation factors. Using muons at 90deg. For the modules non exposed to the testbeam we have seen that the response from the muons can be transported via Cs with a precision of 1-2%. How will it be for ATLAS? We are now investigating the combination of all the tools looking thoroughly at the testbeam calibration experience. It is important to remind that even with using one EM scale factor per module and exploiting the Cs equalisation, the pion reconstructed energy seems to be good to 1.5% level.