Cosmic Ray Test of GEM-MPI/TPC in Magnetic Field

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Cosmic Ray Test of GEM-MPI/TPC in Magnetic Field

• Hiroshima University
• Kuroiwa
• CDC Group

Mar. 4. 2005
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MPGD-Readout TPC

• TPC
• MWPC (Multi Wire Proportional Chamber) readout
• Two-track separation capability gt 1cm
• MPGD (Micro Pattern Gas Detector) readout
• GEM , MicroMEGAS
• Performance test of GEM-TPC by cosmic ray

Requirement Requirement
Spatial resolution sx lt 150µm sz lt 1mm
Two-track sep. ?2hit lt 2mm
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GEM as the Readout MPGD

• Almost no EB effects ? good spatial resolution
• Fast and spatially narrow induced signals
• ? good two-track separation
• No wire ? thin sector boundaries
• Suppression of positive ion feedback

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GEM-MPI/TPC

• MPI/TPC
• Field cage Maximum drift length 27cm
• Pad plane 10cm10cm
• Gas TDR (Ar CH4 CO2 93 5 2)
• Readout MWPC ? GEM

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GEM-MPI/TPC

• GEM
• 10cm10cm
• Cu electrodes 5µm thick
• Bi-conical holes due to
• chemical etching (CERN)
• 3 GEM plane
• VGEM 320V

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GEM-MPI/TPC

• Pad
• Pad plane 1264 pads cover 10cm10cm
• Pad size 2mm6mm (0.3mm gap)
• Readout channels 7 pad rows12 pads

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Experimental Setup

• Setup
• Trigger scintillation counter3 , 1027cm
• E-field 300V/cm
• B-field 1T
• VGEM 320V
• Gas TDR

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Result

• X resolution (Row 1)

nominal residual (sn.r.) from track without
self info Row 1 has the worst tracking
error in all rows
geometric mean s sqrt(sn.r.sfull) sfull
from track with self info
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Result

• X resolution (Row 6)

nominal residual tracking error is small in
the middle row
geometric mean s shows almost same behavior
as the row 1 Effect of large-pad size
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Pad Size

• Change the pad width

Pad width 2mm
Pad width 1mm produced by the end of March
Beam test at KEK-PS in April and June
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Summary and Plan

• Summary
• Geometric mean of row 1 and row 6 show almost
  same behavior.
• Effect of large-pad size
• Plan
• 1mm pad
• Cosmic ray test
• Beam test at KEK-PS in April and June
• GEM , MicroMEGAS