SSD Status

P. Christakoglou (NIKHEF-UU)

for the SSD collaboration

Thanks to: Marco vL, Enrico, Mino, Marek and Massimo

Status of the DA

Pedestal DA is in AliRoot since last November

Main program ITSSSDpedDa.cxx and three support classes: AliITSHandleSSD, AliITSModuleSSD and AliITSChannelSSD

Sasha Borysov was the main developer but now he moved back to Ukraine We will identify the person to take over

in the upcoming SSD meeting The latest version was installed around

mid-July and since then no upgrades were performed This latest version uses the new

calibration object scheme (see next slides)

Sasha Borysov

There is an ongoing discussion among the SSD collaborators about the necessity to have an additional DA that will run during the physics runs and will monitor the noisy-dead strips and update the bad channel list accordingly at the EOR.

Status of the calibration objects

We were asked to move to a new format of the calibration objects: 1698 objects replaced by one single object During this transition, backward compatibility was lost This was fixed around mid-July by providing a new set of classes and an

interface to convert the old calibration objects to the new ones (AliITSNoiseSSD AliITSNoiseSSDv2)

Noise: $ALICE_ROOT/ITS/Calib/NoiseSSD alien:///alice/…/OCDB/ITS/Calib/NoiseSSD Updated after every “PEDESTAL_RUN”

Bad channels: $ALICE_ROOT/ITS/Calib/BadChannelsSSD alien:///alice/…/OCDB/ITS/Calib/BadChannelsSSD Updated after every “PEDESTAL_RUN”

Gain: $ALICE_ROOT/ITS/Calib/GainSSD alien:///alice/…/OCDB/ITS/Calib/GainSSD Static map – Updated manually

Pedestal $ALICE_ROOT/ITS/Ref/PedestalSSD alien:///alice/…/Reference/ITS/Ref/PedestalSSD Updated after every “PEDESTAL_RUN”

Status of the preprocessor

The last time the preprocessor was changed was also around mid-July in order to adopt the new calibration format.

Since then it is running stably without any problems.

Calibration strategy

Take advantage of the high statistics of cosmic data to start looking at the gain calibration for smaller segmentations: Currently we apply different gain factors for P and N-side Difference per DDL, per side, per layer, per ladder?

Starting to look offline on the energy loss coming from the two SSD layers (Marek Chojnacki)

For the two tasks above we need to access the ITS.RecPoints.root, the AliESDs.root and the AliESDfriend.root files offline.

If needed, only the gain calibration file will be modified. Offline analysis of standalone noise runs to refine the bad channel list

(Massimo Venaruzzo) Include the treatment of strips with non-Gaussian noise

Status of survey and alignment

2 types of measurement:• Modules on ladder• Ladder endpoint on cones

AliAlignObjParams:1 per module1 per ladder

Measurement tip

AliITSSurveyToAlignSSD

The official offline approach was followed:• The survey report was put in EDMS and then in the DCDB• A class was committed in aliroot to convert the survey points into AliAlignObjParams• Merging with the SDD is an ongoing activity• We expect shifts up to 200 μm in R and z and rotations of up to 1 mrad in φ.Marco van Leeuwen

Status of the QA (I)

Online QA: We used both MOOD and AMORE MOOD is considered to be the SSD’s expert’s tool AMORE is used by the standard shifter

We monitor the raw data but there is an ongoing discussion to include also the rec. points based on the implementation of the SDD colleagues (P. Cerello).

We defined ~1.5 K histograms which are structured in a hierarchical way.

For the offline shifter, we put the flag to the 4 most representing objects– Average data size per DDL and per LDC– Average module occupancy for layer 5 and 6

We also monitor the calibration objects put in the OCDB (AliEn)

Is it foreseen to publish somewhere the results of the prompt offline QA?It would be nice to have them available either in the e-logbook or somewhere else.

Status of the QA (II)

Offline QA Work in progress on the definition of the quality checks since we

start to understand the behavior of the detector. Checks based not on reference data but on on-the-fly

calculations/fits

READYIN

PROGRESSNOT

STARTED

SOURCE Definition Code SVN Checks

Ofline – Hits

Offline – Digits

Offline – SDigits

Offline – RAW

Offline – Rec. points

Offline – ESDs

Status of the cluster finder

Results from the last cosmic runs Ongoing activities• Raw & digits reconstruction: Uniform treatment of 1D-clusters reconstruction from raw data and from digits.• 5 seed: CF reconstructs clusters summing only adjacent signals above 3 noise sigma, with at least one strip above 5 (the 5 seed was requested only for single strip clusters before, noise correlation between neighboring strips was not considered).• CM pseudochannels: additional channels used to store common mode noise values are now considered by the CF. Still to come• Bad channels: Include the bad channels in the reconstruction (excluded for the time being).• New rec. points classification: geometrical matching between P and N-side, charge matching (based on the experience from cosmic data.• Benchmarking and fine tuning of the code

Enrico Fragiacomo and Mino Contin

BACKUP

Definition of bad channels

Noisy strips Noise after CM correction > 20 ADC

Dead strips Noise before CM correction < 1 ADC

Pedestal out of range |Pedestal value| > 512 ADC