The Status of the Data Analysis of the Beam Test at FZJ March, 8th 2010 | T. Randriamalala, J. Ritman, T. Stockmanns and H. Xu

Outline Introduction Raw Data Structure Data Analysis Chain in PandaRoot Data Analysis Detector Alignment Conclusion

Introduction Proton beam test of the Bonn silicon tracking station has been performed at Cosy at FZJ on February 2nd , 4th and 5th 2010. Different geometries and 2 beam momenta (2.95 GeV/c and 0.893 GeV/c) were used (cf Huagen Presentation) The whole frame and the software interface have been designed and built by the Bonn Group. Goals: Mvd development, LM digitization process test. Participants: Mvd Bonn Group, LM Jülich Group. Data analysis is being performed within PandaRoot fromework.

Scintillator fiber trigger sytem 4 Single-Sided Silicon Strip Sensors Scintillator fiber trigger sytem 2 Double-Sided Silicon Strip Sensors Picture of the BonnTracking Station

Raw Data Structure Event trigger : 3 coincidence hits of the 4 scintillating fibers 24 APV front-end (labelled from 0 to 23) 128 channels per front-end (labelled from 0 to 127) Sensor thickness : 300mm Pitch : 50 mm

Data Analysis Structure Geometry & Digi Parameters Data & Calibration Files PndMvdCreate-DefaultApvMap Geometry Map PndLumiConvertApv Digitization Hits PndLumiClusterTask Reconstructed Hits PndLumiTrackFinder Parfile.root is used by the geomanager Track Candidates PndDmlLinFitTask Reconstrcuted Tracks ref: https://subversion.gsi.de/trac/fairroot/browser/pandaroot

Data Analysis (1) Data analysis of the first day run: Beam momentum : 2.95 GeV/c z-positions : Box1: 110mm, Box2: 807mm, Box3: 1390mm, Box4: 1832mm. x-position shift from the beam axis: Box1: -6mm, Box2: 4mm, Box3: -1mm, Box4: 1mm. Average noise: 500 electrons Threshold: FE 0-17: 3000 electrons (first 6 sensors) FE 18-23: 6000 electrons (last sensor) Confrontation with MC simulation is carried out along the analysis.

Data Analysis (2) Sample data : 34632 events Digis multiplicity per event

Data Analysis (3) mx =-0.343cm, sx=0.64cm my =-0.01cm, sy=0.3cm Strip fired at the first plane: This shows the beam particle distribution on x and y coodrinates: mx =-0.343cm, sx=0.64cm my =-0.01cm, sy=0.3cm Psi(2S) mass = 3686.09 and width=0.04 MeV An excitation curve (of the rate) is obtained by stepping the beam momentum across the expected mass of the state Resonance scans: measure the event yeild for the reactions of interest as a function of E_cm, a excitation profile is obtained from which the resonance parameters could be extracted: deconvolute the E_cm spectrum from the excitation curve and obtain the intrinsic resonance shape.

For MC simulation, the beam smearing was applied for primary particles with the obtained values. After the digitization process, the strip fired distribution at the first plane: The angular divergence needs to be calculated !

DATA SIMULATION Clusterization The cluster size: Difference is due to the non-implementation of the angular divergence for the MC simulation : MC Tracks are normal to the detcctor surface Charge Calibration :

DATA SIMULATION dE/dx [eV] Factor of 2.25 of difference Strip ID ~40 keV ~ 90 keV DATA SIMULATION dE/dx [eV] Factor of 2.25 of difference Strip ID

DATA SIMULATION Tracking (1) The track finder consists in collecting hits which are close to each other in xy plane within an area of dr of radius. With the same search radius: DATA SIMULATION

Misalignment of the sensors! Tracking(2) However, the number of reconstructed hit per event per plane DATA SIMULATION Most of the case: multiplicty 1 (1 track per event) Reconstruted hits are far from each other for the data. Misalignment of the sensors!

Alignment Detector alignment proposition (on x and y): Focus on 1 hit multiplicity per plane Middle plane Fit the first two hits on one line and the last two on another line (step 1) Calculate the difference on x, y, q and j of the intersection points of the two with a virtual middle plane (step 2) dx,y,q,j

DATA SIMULATION Result: Unlike the MC simulation, the 2 lines from data have not the same direction. Goal : reduce dx,y < 7mm (hit resolution) SIMULATION

Fit the 4 hits and calculate the difference between the hit position and the fit line position at each plane (step 3). Data Simulation

Shift the detector on x and y by the means of those distributions (step 4) ( Output of steps 1 & 2)

Redo step 3 Redo step 4

sx,y~6mm The 2 lines become colinear

Result Initial Position (cm) Final Position (cm) Box1 (-0.600, 0.000, 11.000) (-0.274, 0.072, 11.000) Box2 ( 0.400, 0.000, 80.700) (-0.292, -0.082, 80.700) Box3 (-0.100, 0.000, 13.900) (-0.038, -0.090, 13.900) Box4 ( 0.100, 0.000, 18.320) ( 0.069, 0.102, 18.320)

Conclusion We had a successfully data acquisition for the Bonn tracking system beam test. Data analysis is ongoing. A proposition of detector alignment on xy plane has been described.. A confrontation of the data with .the MC simulation has been shown. The beam divergence needs to be determined for further studies. To be continued …

Thank you!

Multiply charge at every strip by 2.25 Peak at 80 keV