MTCC –II & HCAL noise chasing

Mandakini Patil

India-CMS meeting21-22 Jan07

Shantiniketan.

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..

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.

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..

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

Actual HO RBXs installed for MTCC

● Ring0 sector 10

● Ring1 sector 3,4 ,9 and 10

● Ring2 sector 3,4,9 and 10

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 .

Noise in global data (timing of HCAL events above 10fC wrt

CSC trigger)

Nu

mb

er o

f ch

ann

els

wit

h E

>10

fC

How we realized, we have a problem:,Over 6k entries for 20k triggers,Timing of signals not synchronized DT trigger

timing of HCAL signals>2GeV,

r3533, 2T field (10kA)

Good timing,(HO is ok at 10kA),Only 74 evts per 20k triggers

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

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

Blowup of noise,(local r1302)

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

Local LED/ped R1302,HB, w15/, Bfield=2T

Event number

HT

R c

han

nel

nu

mb

er

Single eventMultiple hits

Noise vs Bfield 1

(B=1T around HPD)

Noise vs Bfield

(B=1T around HPD)

Noise vs Bfield 3

(B=1T around HPD)

Noise vs Bfield 4

(B=1T around HPD)

Noise vs Bfield 3

(B=1T around HPD)

Noise vs HV (YB1/S9, S10)

Exponential increaseof noise vs HV,Is onsistent with HV discharges

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..

Noise count vs HPD pixel position

Each eta-phi tower on detectorCorresponds 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

Noise count vs HPD pixel position

Each eta-phi tower on detectorCorresponds 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

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..

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)

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