Tracking Algorithms

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## Tracking Algorithms

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**Tracking Algorithms**Hervé Savajols & Thomas Roger (GANIL) Wolfgang Mittig (MSU) …**❍ For particle leaving MAYA at**forward angles, identification is given by the energy loss in MAYA, energy deposit in Si and CsI wall ❍ For particle stopping inside MAYA, identification is given by the energy of the particle and its Range : He t t d p d p Range ∝ E2/MZ2 Maya identification ❍ Reconstruction of the reaction kinematics**Event analysis**Event display of pads signals. Each dot shows the pulse height of the pad Drift time distribution • - Selection of the particle in Si • Projected trajectectory • reconstruction • Theta2D and Range2D • - Vertex (target depth) • - Reaction plane angle ❍ Energy resolution ❍ Angular resolution Range resolution ≈ 1mm ∆θ ≈ ∆x/R (0.6 deg for R=10cm) ∆R/R ≈ 1mm/R (≈ 1% for Range = 10cm) ∆E/E = 0.5*1/R (≈ 0.5% for Range = 10cm) Charge resolution ~ 10 % Vertex resolution ~ 3 mm**11Li(p,t)9Li**3. Event output - Class LogFile - Class Eventouput - Class EventDisplay 1. Event Generator - Class Nuclei - Class Reactions - Class CrossSections - Class Event - Class EventOutput ∆E = 120keV 2. Detector - Class EnergyLoss - Class ActiveAreaGeometry - Class AncillaryDetector 4. OfflineAnalysis - Class Identification - Class ParicleTracking Hervé Savajols, GANIL Handy simulation software is necessary • Because of the energy loss in MAYA • Beam energy changes depending on the depth into MAYA • Energies detected in Si or CSI depend strongly on the reaction point. • Angular acceptance depend on the reaction point**Hyperbolic secant squared method**- principle - Induced charge distribution from a point source -> search of maxima along symetry axis**Hyperbolic secant squared method**- results - Calculated angle is shifted around 0° and 60° Extreme points has to be removed from the fitting procedure... -> Range has to be greater than 4 pads**Global Fitting method**Orthogonal distance regression Good resolution if only one track Problems if two or more tracks -> used for thin tracks. Range has to be greater than 3 pads**Getting 3rd dimension**Time from wires used to extract reaction plan10e angle -> angle < 60°**Test of a complete algorithm**- case of p(11Li,9Li)t reaction -**Geometry definition of the next active target**Cylindrical geometry: symmetry around beam axis E // beam axis, uniform Projection on the endcap of the cylinder B // beam axis ASIC cards Pads Anode Cathode 50cm O 50cm Gangnant@ganil.fr Quantities to be measured: curvature radius, collected charge, range, angles For 0.5 mm position resolution, ΔE/E=2ΔR/R, expected energy resolution≈100 keV for θcm>20°