1. MTCC –II & HCAL noise chasing Mandakini Patil India-CMS meeting 21-22 Jan07 Shantiniketan.

2. Plan of the talk ● Work involved in MTCC2 ● Data analysis..i.e ● LED data- Local runs for HCAL ● Global data runs.. ● Things learnt from this analysis..

3. Pre-requisites for the analysis.. ● Location of the data. ● Account on various machines to access the data and the analysis codes and the HO map file. ● How to use the CMSSW and ROOT.

4. Initial Work involved.... ● Understanding the procedure of the data taking..that is using the xdaq. ● Configuration of the test setup involved.. ● The various aspects of the CMSSW ● The understanding of the existing codes for data analysis..and how they need to be modified..

5. Recalling Some useful facts.. ● The Readout box components : Readout modules(RMs), Calibration Module, CCM, LEDs ● RM :HPD(18 pixels); each pixel: each tile ● LED data Run: on pixel data and off pixel data ● LED local data : reflection of the electronics ● Global data : reflects quality of the subdetector

6. Actual HO RBXs installed for MTCC ● Ring0 sector 10 ● Ring1 sector 3,4,9 and 10 ● Ring2 sector 3,4,9 and 10

7. Chasing the Noise in the HCAL ● The global HCAL data showed noise that increased with the rampup of the Magnetic field.. ● Investigation of the different sections of the hcal was therefore done for local LED data too.. ● Strong corelation of noise(of local and global data) seen.

8. Noise in global data (timing of HCAL events above 10fC wrt CSC trigger) Number of channels with E>10fC How we realized, we have a problem:, Over 6k entries for 20k triggers, Timing of signals not synchronized DT trigger

9. timing of HCAL signals>2GeV, r3533, 2T field (10kA) Good timing, (HO is ok at 10kA), Only 74 evts per 20k triggers

10. Pedestal run, 2T setting, HB quiet RM, (local r1302)

11. Pedestal run, 2T setting, HB noisy RM, (local r1302)

12. Blowup of noise, (local r1302)

13. LED run R1302 Plot showing that noise events have multiple pixels lighting up

14. Local LED/ped R1302, HB, w15/, Bfield=2T Event number HTR channel number Single event Multiple hits

15. Noise vs Bfield 1 (B=1T around HPD)

16. Noise vs Bfield (B=1T around HPD)

17. Noise vs Bfield 3 (B=1T around HPD)

18. Noise vs Bfield 4 (B=1T around HPD)

19. Noise vs Bfield 3 (B=1T around HPD)

20. Noise vs HV (YB1/S9, S10) Exponential increase of noise vs HV, Is onsistent with HV discharges

23. New observations of HO Noise ● eta-phi distribution is not flat ● Distributions of noise are mirror symmetric (for HO, YB+1, s9 and s10) ● They map out into HPD pixels in specific way ● Noise seems to originate from a single location on the HPD surface (edge) ● We see multiple pixels seeing noise in a single event ● Noise data consistent with HV discharges..

24. Noise count vs HPD pixel position Each eta-phi tower on detector Corresponds to a single pixel on HPD Maps are same for: YB1/S9 (phi=47, 48, 49) YB1/S10 (phi=58, 57, 56) 20 26 28 222 286 357 72 149 190 272 32 126 71 74 57 58 x 133 201 RM2, phi=47-49

25. Noise count vs HPD pixel position Each eta-phi tower on detector Corresponds to a single pixel on HPD Maps are same for: YB1/S9 (phi=47, 48, 49) YB1/S10 (phi=58, 57, 56) 43 44 76 216 254 359 94 156 189 344 53 146 91 145 83 64 x 182 314 RM1, phi=56-58

26. New observations ● eta-phi distribution is not flat ● Distributions of noise are mirror symmetric (for HO, YB+1, s9 and s10) ● They map out into HPD pixels in specific way ● Noise seems to originate from a single location on the HPD surface (edge) ● We see multiple pixels seeing noise in a single event ● Noise data consistent with HV discharges..

27. RBX setup in b157 (meyrin)) ● In B157, we have magnet going up to 1T ● Data being taken with HCAL RBXes to study pixel cross talk vs Bfield ● This setup was used to understand HCAL noise Noise effect was reproduced in HO RBX at B=0.3T (no noise at B=0T)

28. Conclusion  Effect depends on Bfield  Effect depends on HV  Effect does not depend on Bias voltage  Effect stays with RBX (or RM). It is not caused by faulty Bulgarian power supply  Effect is seen in both pedestal (local trigger) and muon-triggered global data  Effect is present in both LED on and off  Effect is present during ramp-up, flat-top of the magnet and during ramp-down, even when all magnet power supplies are disconnected