tracking algorithms

ACTAR meeting - Dec 10th 2008Hervé Savajols (GANIL)

Tracking AlgorithmsTracking Algorithms

Hervé Savajols & Thomas Roger (GANIL)Wolfgang Mittig (MSU)

…


Cubic Geometry

11Li beam

9Li

PPAC

MAYA target-detector

SSD and

veto SSD


MAYA : the MAYA : the moviemovie

QuickTime™ et undécompresseur GIF

sont requis pour visionner cette image.

4ACTAR meeting - Dec 10th 2008Hervé Savajols (GANIL)

❍ For particle leaving MAYA at forward angles, identification is given by the energy loss in MAYA, energy deposit in Si and CsI wall d

p

t

He

p d

t

❍ Reconstruction of the reaction kinematics

❍ For particle stopping inside MAYA, identification is given by the energy of the particle and its Range :

Range ∝ E2/MZ2

Maya Maya identificationidentification


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

Event Event analysisanalysis

❍ 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

6ACTAR meeting - Dec 10th 2008Hervé 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

1. Event Generator

- Class Nuclei

- Class Reactions

- Class CrossSections

- Class Event

- Class EventOutput

2. Detector

- Class EnergyLoss

- Class ActiveAreaGeometry

- Class AncillaryDetector

4. OfflineAnalysis

- Class Identification

- Class ParicleTracking

Hervé Savajols, GANIL

3. Event output- Class LogFile

- Class Eventouput

- Class EventDisplay

11Li(p,t)9

Li

Q-value measurement

∆E = 120keV


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 -


Range measurement

13


14


15


16


Geometry definition of the next active Geometry definition of the next active targettarget

Cylindrical geometry: symmetry around beam axis E // beam axis, uniform Projection on the endcap of the cylinder

B // beam axis

Anode

PadsASIC cards

[email protected]

Cathode

O 50cm

Quantities to be measured: curvature radius, collected charge, range, anglesFor 0.5 mm position resolution, ΔE/E=2ΔR/R, expected energy resolution≈100 keV for θcm>20°

50cm

17


K.Tyler & W.Mittig (MSU)

18


19


tracking algorithms

Documents