Offline software: status and some results of

E.Choumilov, TIM 21.07.08 1

Offline software: status and some results of January-June 2008 data acquisition period.

E.Choumilov

TIM July 21.07.08


1.Status of TOF, ECAL, TrigLev1 and ACC parts of the offline reconstruction program.

2. Status of calibration programs.

3. Status of monitoring programs.

4. Problems and plans.


Reconstruction programs status.

TOF/ACC: 1) Raw format data decoding and reconstruction codes are ready and used during the standard root-files production. Some DAQ system errors diagnostics and debugging tools were implemented and used as “online feedback” during the first periods of data acquisition. On the request detailed diagnostics table is printed at the end of standard reconstruction job. 2) TOF compressed format data decoding codes are ready but not tested (lack of data).

ECAL: 1) Compressed format data decoding and reconstruction (EcalHit-objects creation) codes are ready and tested.


DAQ errors diagnostics is also implemented. Related summary table can be printed on request.

2) “Downscaled” events handling is implemented (used also for pedestals calculations).

TrigLevel1: 1) The codes for decoding and processing of TOF, ACC and ECAL trigger-patterns, live-time and setup information are ready and tested. DAQ system errors diagnostics is also implemented. Scalers information handling codes are not yet final and tested.

2) Current DAQ system logic put trigger-setup information in every event. Current reconstruction logic can save the setup information into DB each time it was changed (definitely at the beginning of every run). This feature is


activated through the dedicated data card but was not really used.

Calibration programs status.

TOF/ACC: 1) Pedestals calibration: - TOF “on-board” pedestals manipulation codes are preliminary and not tested yet (lack of data). - Currently used pedestals are extracted from “scientific” data type events by special interactive program using raw format of the data. This is a temporary mode for TOF and may be final mode for ACC. These pedestals were written into the DB by this program and were used during the root-files production.

2) TOF channels time-related calibration:


- TDC-channels linearity calibration. Program do not use any special calibration runs (only normal “scientific” events, but require many millions events). The picture below illustrates integral linearity caused by the chip production technology and measured over 25ns TDC-bin. The real time measurement falls in one of 1024 sub-bins of horizontal axis. Necessary time-correction is vertical coordinate for this particular bin. Calibration was done only for TOF low threshold (LT) and fast trigger (FT) channels of every TDC-chip (excluding ones in

SFEA-cards).



- TOF inter-paddles and inter-sides timing offsets and time-amplitude correlation parameter. Calibration parameters were extracted for each counter/side using “scientific” DAQ-files and special mode of reconstruction program (modified version of procedure used for AMS-01). These parameters are responsible for correct TOF velocity and coordinates measurements. Eight sets of calibration parameters were produced and written into DB to cover whole data taking period mainly following to recognized changes in HV, threshold and other TOF settings (some changes could be omitted !). New sets can be added (after that related root-files have to be recreated). This calibration procedure is used after the TDC linearity corrections are applied (otherwise the single paddle time resolution shown below will degrade by about 10ps). The pictures below illustrate some results of described calibration (very preliminary because some PMTs was not powered).




3) TOF energy loss measurement calibration.

PM-anodes and PM-dynodes channels need calibration of amplification factors. Related program was developed and tested. For the moment only anode channels parameters were extracted and written into DB ( muons dynode and low gain channel signals are too small to give complete set of reliable parameters). Absolute normalization and longitudinal uniformity of the counter response were calibrated for most of both sides powered counters. For the moment the absolute normalization factor is very preliminary due to missing information about the particle momentum. The pictures below illustrate some calibration results.



4) TOF “geometry” calibration : To explain some indications on systematic shift of measured velocity simple geometry check was done using the tracker information. The average difference in transversal position of fired counter and crossing point of the track extrapolated to this counter can give the information on the counter transversal and Z-position if plotted as function of the track impact angle. The slope of the correlation line gives the vertical shift between the implied and real Z-positions. Based on this study the software top/bottom TOF-planes positions were changed so that distance decreased by about 1.6 cm. Z-position phase between even/odd counters in plane was also changed to opposite in all planes. These changes was already used in production runs. Pictures below illustrate some details of this kind of calibration. Meanwhile Vitaly Choutko developed universal (applicable for all sub-detectors) program which extract also the planes inclination angles.


Line slope parameters p1 are z-shifts relative to design positions.


Z-shifts for odd counters in four planes.


Z-shifts for even counters in four planes.



Even counters z-shifts after correction (about +-1mm due to inclination)


5) ACC response absolute normalization, uniformity and timing : Existing calibration program works with DAQ-files and needs some modifications. More efficient mode (to work with root-files) could be implemented (as I know ACC group is working for that, so i propose to use some ideas from DAQ-files oriented program). For the moment ACC energy loss information in root files is not properly calibrated, but necessary for calibration raw ADC/TDC information is attached (AntiRawSideR object). Pedestal subtraction is already done. Some cables swapping in early runs is corrected. Pictures below illustrate that ACC and the reconstruction program give quite reasonable results using just AntiRawSideR data (efficiency level is very preliminary).



ACC efficiency versus azimuth angle.


ECAL : 1) Pedestals calibration : - “On board” pedestals handling codes are ready but not tested (missing pedestals blocks). - Instead “downscaled” events and special mode of reconstruction program were used to extract pedestals. ECAL data in root files are pedestal-subtracted. Information on used pedestals is attached. 2) Channels amplification factor calibration: - DAQ files oriented calibration program tested, need some improvements and tuning. - Pixel’s high gain channels are pre-calibrated. Accuracy have to be improved (difficult to do because amplitude spectra are too close to “0” – most-probable values are about 4-6 ADC, so results can be affected by temperature drift and other factors). Picture below shows some spectra. For the moment this calibration is not applied in root files data. - Pixel low gain and dynode channels calibration is also not applied (muon signals are too small) but related codes are tested.



- absolute normalization calibration was not done (need electrons and momentum measurement from tracker). Program exist but tested only on MC-data.

Offline monitoring program status.

Developed by V.Choutko prototype is now filled with initial setof histograms for TOF, ACC, ECAL, RICH and TrigLev1 as an examplefor developers from sub-detector groups. This program use root files asinput and can be used in near real time mode to monitor AMS dataquality. Few examples of real data monitoring are shown below.








Problems and plans. (first priority items)

1) ACC : - pedestals vs SFEA temperature (offline(?) correction);

2) TOF : - pedestals vs SFET temperature (on board correction procedure is developing by A.Kounine, if successful – to do the same for ACC on-board is natural to my mind, decision by ACC group !); - timing ((LT-FT)-time or separately) vs temperature; - “around counters” (SFEC, PMT) temperature monitoring; - dynodes pedestals vs SFEC temperature; - amplification factors vs temperatures;

3) ECAL : - pedestals vs temperature; - amplification factors vs temperature;


I hope that the results of passed TV-tests can be used to develop algorithms. Otherwise special laboratory tests have to be done (clean room temperature variations are too small to study above problems).

4) Revision of existing calibration procedures to improve performance on the basis of recent experience.

5) Revision of “online” monitor to improve information/histogram ratio and add missing sub-detectors (tracker at least). *** To do more reliable analysis of existing data we need to have good (or bad) “scientific” runs list from each sub-detector and exact dates (run numbers) of any settings changes. ***

Software developers from sub-detectors groups are welcome !!!

Documents

Offline software: status and some results of