1. Linear Collider TPC R&D in Canada Madhu Dixit Carleton University

2. Stanford 25/9/2003M. Dixit

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5. Stanford 25/9/2003M. Dixit ExB cancels track angle effect TPC wire/pad readout 100 µm Average Aleph resolution ~ 150 µm About 100 µm best for all drift distances Limit from diffusion  (10 cm drift) ~ 15 µm;  (2 m drift) ~ 60 µm 100 µm limit for all drift distances comes from wide pad response ExB & track angle systematics in a TPC (Aleph TPC example)

6. Stanford 25/9/2003M. Dixit

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9. Stanford 25/9/2003M. Dixit TPC read out with a Gas Electron Multiplier (GEM * ) How to find charge centroid in a GEM? –Zigzag shape makes chevrons share charge between pads to facilitate centroid finding –Optimize readout geometry and diffusion to do the best with rectangular pads –Where is the induced signal on the neighboring pads? * F. Sauli, NIM A386,531 (1997) GEM spatial resolution ~ 40 µm with 200 µm pitch anodes Impractical for a TPC TPC pad widths ~ mm All charge on a single pad for a TPC in high B field Difficult centroid finding Resolution ~ Pad width/√12

10. Stanford 25/9/2003M. Dixit MPGD-TPC R&D in Canada - Goals New ideas to get good space-point resolution from ~ mm wide pads –Studies with a GEM & Micromegas test cells using collimated x-rays Limits to achievable resolution by with conventional techniques by optimizing geometry and gas diffusion –15 cm drift TPC with GEM readout –Operating parameters –Cosmic ray tracking studies Assess the performance of MPGD-TPC in a test beam and in a high magnetic field  (r-  ) ~ 70 µm within reach with R&D,

11. Stanford 25/9/2003M. Dixit

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14. Stanford 25/9/2003M. Dixit Pads centroid from induced signals in a GEM GEMProportional wire Cathode padsAnode pads Short ~ 200 ns signal Wire/pad readout electronics won’t work! Need fast high frequency pulse shape sampling electronics

15. Stanford 25/9/2003M. Dixit

16. Stanford 25/9/2003M. Dixit Resistive anode GEM test cell setup

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20. Stanford 25/9/2003M. Dixit Outlook & summary Consensus for a 500 GeV e + e - linear collider within this decade - proposals in Europe & in the US & Japan A micro-pattern detector (MPGD) readout TPC is being be developed for the LC detector with resolution and 2 track resolving power approaching diffusion limits Better MPGD-TPC resolution has a significant impact on the design of the LC detector design and its physics reach