1. Cosmic Ray Test of GEM- MPI/TPC in Magnetic Field Hiroshima University Kuroiwa CDC Group Mar. 4. 2005

2. MPGD-Readout TPC TPC – MWPC (Multi Wire Proportional Chamber) readout Two-track separation capability > 1cm – MPGD (Micro Pattern Gas Detector) readout GEM, MicroMEGAS Performance test of GEM-TPC by cosmic ray Requirement Spatial resolution σ x < 150μm σ z < 1mm Two-track sep.Δ 2hit < 2mm

3. GEM as the Readout MPGD Almost no E×B effects good spatial resolution Fast and spatially narrow induced signals good two-track separation No wire thin sector boundaries Suppression of positive ion feedback

4. GEM-MPI/TPC MPI/TPC – Field cage : Maximum drift length = 27cm – Pad plane : 10cm×10cm – Gas : TDR (Ar : CH 4 : CO 2 = 93 : 5 : 2) – Readout : MWPC GEM

5. GEM-MPI/TPC GEM – 10cm×10cm – Cu electrodes 5μm thick – Bi-conical holes due to chemical etching (CERN) – 3 GEM plane – V GEM : 320V

6. GEM-MPI/TPC Pad – Pad plane : 12×64 pads cover 10cm×10cm – Pad size : 2mm×6mm (0.3mm gap) – Readout channels : 7 pad rows×12 pads 6mm 2mm 0.3mm

7. Experimental Setup Setup – Trigger : scintillation counter×3, 10×27cm – E-field : 300V/cm – B-field : 1T – V GEM : 320V – Gas : TDR

8. Result X resolution (Row 1) nominal residual (σ n.r. ) from track without self info Row 1 has the worst tracking error in all rows geometric mean σ = sqrt(σ n.r. σ full ) σ full : from track with self info

9. Result X resolution (Row 6) nominal residual tracking error is small in the middle row geometric mean σ shows almost same behavior as the row 1 Effect of large-pad size

10. Pad Size Change the pad width Pad width : 2mmPad width : 1mm produced by the end of March Beam test at KEK-PS in April and June

11. 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