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Proportional chambers with cathode readout in high particle flux environment. Michał Dziewiecki. The GSI. Temperature T (MeV). Density ρ / ρ 0. GSI – a heavy ion research facility, Darmstadt, Germany FAIR – Facility for Antiproton and Ion Research –
Temperature T (MeV)
GSI – a heavy ion research facility, Darmstadt, Germany
FAIR – Facility for Antiproton and Ion Research –
a futureheavy ion accelerator centre
CBM –Compressed Baryonic Matter Experiment –
Its main aim will be to obtain a quark-gluon plasmaat very high nuclear matter density but moderate temperatures.
It can be achieved by colliding heavy (Au) ions against an Au target.
TRT 1 (Transition Radiation Tracker)
Heavy ion (Au) beam
Target (0.3mm Au)
RICH (Ring Imaging Cherenkov Detector)Detector setup of CBM
1st: 5.8 x 3.9 m
2nd: 8.7 x 5.8 m
3rd: 11.6 x 7.7 m
Each TRT module consists of 6 independent detectors.
Total TRTs’ area: 500 m2
The aim is to extract high energy electrons from a huge amount of pions crossing the detector plane.
Requested pion suppression factor - 300
The detector can be also used for particle track reconstruction.
3 modules, 3 double detectors per module, inclined at angle of 0, +10 and –10 degrees vs the vertical orientaton
High collision multiplicity (300-400 particles per collision), up to millions of collisions per second
Electron + photon beam
(a set of foils)
Straw chamberTRT operation principle
Radiator: 250-300 foils
Straws: 3-6mm diameter,
Ionization clusterProportional counter –single section of a straw chamber
Charged particle producesionization clusters
A photon produces only one, but relatively large cluster
Electrons drift to the anode along the potential gradient
Near the anode the electric field is strong enough to cause a secondary ionization (electron avalanche).
Resultant ions drift to the cathode, causing measurable current flow through the counter.
Δt = f(x)Position estimationAnode readout
Cathode stripsPosition estimationCathode readout
It’s one of the most significant problems by cathode readout.
The ADCs at CBM will be working at 20MHz sampling rate, thus the pulse width can not be shorter than 200ns.
Exemplary error distribution (central part)Computer simulation
A Monte-Carlo simulation was executed in order to analyze the problem
Particle flux[part·mm-2·s-1] ·100
Guarateed accuracy for 80, 90 and 95% of particlesSimulation resultsand conclusions
Position calculationExperimental verification of obtained results
A small model of chamber is being built to verify the simulation results.