1

Detector Algorithm Quality Assurance Experience with cosmic ray data taking Reconstruction Alignment

PMD Software Status

Outline

ALICE offline week, CERNAjay Kumar Dash For the PMD

2

Raw Data

Pedestal

ESD

Hits

SDigits

Digits

Clustering

Simulation

keV-ADC Conversion From Test Beam

Hardware Mapping information

Flow chart of Simulation & Reconstruction for PMD

2003 and 2006 Test Beams

Gain

3

Detector Algorithm (DA)

Two algorithms for PMD

Pedestal DA: Calculates Mean, RMS for each channel No of Events : 1K (to have a better mean and sigma) Mode of data taking : Standalone, LDC

Gain DA : Calculates relative gain of each channel No of events : ~10 Million Execute on monitoring machine

4

DA continuing…..

Pedestal DA

pedestal2304.pedpedestal2305.pedpedestal2306.pedpedestal2307.pedpedestal2308.pedpedestal2309.ped

===>>Load to MARC for zero- suppression

ASCII files

PMD_PED.root ==>> File Exchange Server (FES) ==>> OCDB

Copy stored to DAQ DataBase for GAIN DA

Stores mean and rms for

each channel

5

Pedestal run No : 42155

DA continuing…..

One entry corresponds to one channel

rms (adc)mean (adc)

coun

ts

coun

ts

X

Y

Preshower plane

Modules installed for pp run

6

Lessons from Pedestal Analysis

In the beginning, we were unable to read pedestal raw file Found few bugs in the decoding algorithm

Fixed AliPMDRawStream class Now successfully read the pedestal data as well as simulated RAW data

RAW data writing class “AliPMDDDLRawData” is modified appropriately

Codes are committed to SVN

7

Both plane

adc

From SimulationPYTHIA Minimum bias20K eventsSqrt(S) = 14 TeV

Isolated adc spectra

DA continuing…..

0

0 0

0

0

0ADC>0

isolated cell

Cell to cell gain calibration

Philosophy

Mimics the single particle muon

8

GAIN DA

Minimum entries required : ~ 1k per channel Total # channels : 221184 Total entries required for stable mean ( or MPV) : ~220 Million

Simulation:

PYTHIA Minimum bias @ Sqrt(S) = 14 TeV 20K events => ~ 0.5 Million Entries No of events required : ~ 10 Million pp events

Single particle 1GeV muon

DA continuing…..

9

• One RUN may not be enough to give the required statistics• Need to combine few RUNS

PMD_GAIN_CONFIGFILE(status = 0 Event = 0 MaxEvent )

PMD_PED.root

Event processed >= Max Event

WritePMD_GAIN.root

FES

Change CONFIGFILE (0, 0, MaxEvt)

Write a temp filepmd_gain_tempfile.datChange PMD_GAIN_CONFIGFILE

(1, Evt processed, MaxEvt)

Fetches PMD_GAIN_CONFIGFILE

PMD_PED.root

Does pedestal sub

Isolated cellsearch

False

True

DAQ Data Base

GAIN DA

DA continuing…..

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Quality Assurance

• Hits• Sdigits• Digits• Raw data• Reconstruction• ESD

Implemented at various levels

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Hits Level QA

energy deposition (eV)total hits in preshower plane

cou

nts

cou

nts

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Digits Level QA

total # of cells hit cell adc

cou

nts co

un

ts

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Raw Level QA

Total cell adc

To

tal #

of c

ells

Cell adc

cou

nts

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Reconstruction Level QA

cluster adc# of clusters in 6 modules

cou

nts

cou

nts

• QA histos are also filled for ESD

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• Some preliminary histos are defined in the codes and committed to SVN

• In some histos, scales are not proper

• Also discussing what are the histos to be put

• By the end of this week the final code will be committed as well as the reference histos

Status of QA

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Experience with Cosmic data taking

PMD was included in the Cosmic run

Cosmic data are being analysed

For PMD, it was basically random coincidence

But it was a good experience in debugging the reconstruction software as well as to come across some hardware problem

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Run no : 42290

Experience with cosmic …..

Plots are after pedestal subtraction (Only for one event)

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Lesson from Cosmic

For corrupted event PMD reconstruction was crashing Sometime the FEE board address was wrong in cosmic run, but the pedestals are coming alright. No FEE board address found to be wrong

This problem is under investigation

Remedy

Put protection against the corrupt data in AliPMDRawStream, AliPMDClusterFinder

Modification inside AliPMDClusterFinder to do the reconstruction for active modules

All modified codes are in SVN

19

Reconstruction

Clustering is the main algorithm for PMD reco

In the old clustering algorithm, there are many static dimensions

Everything was cleaned up and made dynamic memory allocation

The code is under the test using the simulated Pythia events

Will be committed by the end of this week

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For Photons

inc Eta of incident photonclus Eta of cluster centre

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inc Phi of incident photonclus Phi of cluster

For Photons

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Macro to generate the Alignment object and to read the survey data points are in SVN

Alignment

Once the detector fiducial points are surveyed, we can immediately generate the misalignment object