Amsterdam Master of Physics symposium 2008 Lucie de Nooij Supervisor: Jan Timmermans Mini TPCs to the max

Detection of charged particles Why? How? cosmic rays Ionisation of mediumMedium? gas silicon LHC

Time Projection Chamber (TPC) Primary electrons drift towards anode Distance = drift velocity * drift time But: a single electron cannot be measured, we need electron multiplication for detection. 25 April 20083Amsterdam Master of Physics Symposium cathode (-)anode (+) charged particle cathode (-)anode (+) charged particle cathode (-)anode (+) charged particle

TPC: wire chamber - wires or plates for detection - pads for readout - position resolution ~ 200 µm - timing resolution ~ 25 ns - granularity ~ 2 mm and 1 cm Charged particle 25 April 20084Amsterdam Master of Physics Symposium 1 cm 2 mm

TPC: Micro Pattern Gaseous Detector - active anode for detection - pixels for readout - position resolution ~ 20 µm - timing resolution ~ 10 ns - granularity ~ 50 µm gas mixture Charged particle

Integrated Grid (InGrid) 25 April 20086Amsterdam Master of Physics Symposium 50 µm 15 cm 14 mm

Drift&Diffusion + anisotropic - E + 25 April 20087Amsterdam Master of Physics Symposium

Less diffusion 25 April 20088Amsterdam Master of Physics Symposium In order to lower diffusion: maximise ω 2 τ 2  high B-field long λ e Switch B-field on: Remember: if B=(0,0,B z ) is applied:where:

My setup 25 April 20089Amsterdam Master of Physics Symposium cosmic

Visuals 25 April 2008Amsterdam Master of Physics Symposium10 Gas mixture: 77% He 23% IsoButane λ e ~ 10µm B=0TB=1T long drift timeshort drift time

Visuals 25 April 2008Amsterdam Master of Physics Symposium11 Gas mixture: 95% Ar 3%CF 4 2% IsoButane λ e ~ 40µm B=0TB=1T long drift timeshort drift time

Analysis Pattern recognition – recongise more tracks – enables “easy” fit Fitting – chi square fit – error corresponds to diffusion 25 April 2008 Amsterdam Master of Physics Symposium12

Analysis & goals Cosmics: Measure diminishing of diffusion as function B-field and gas mixture Measure predicted values of Measure if 25 April 2008Amsterdam Master of Physics Symposium13 More quantitative results in next few weeks! Beam test Measure distortions in electric field

Outlook for Nikhef 25 April 2008Amsterdam Master of Physics Symposium14 Optimising detector characteristics make detector fast measurements at historically low resolution measure many track simultaneously find optimal gas mixture more.. Mini TPCs to the max!! me!!

Mini TPCs to the max Thanks to Jan, Martin, Roel and Joris

25 April 2008Amsterdam Master of Physics Symposium 16 Kleur of lading krachtig of niet op zoek naar een waarheid die niemand ziet. Het ultieme doel het eerste begin je moet het geloven anders heeft het geen zin. Colour or charge forceful or not in search for a truth that no one can see. The ultimate goal the first begin you will need to believe or it won’t work.

Back-up Hough 25 April 2008Amsterdam Master of Physics Symposium17