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Update on TPC R&D

Update on TPC R&D. C. Woody BNL. DC Upgrades Meeting October 9, 2003. R&D Issues. TPC drift cell now working Tests of new 3M GEM foils Electronics developments (see Chi’s talk) Plans for building prototype. Test Drift Cell. Drift Stack (presently 29 cm drift ). Laser.

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Update on TPC R&D

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  1. Update on TPC R&D C. Woody BNL DC Upgrades Meeting October 9, 2003

  2. R&D Issues • TPC drift cell now working • Tests of new 3M GEM foils • Electronics developments (see Chi’s talk) • Plans for building prototype C.Woody, Upgrades DC Meeting, 10/9/03

  3. Test Drift Cell Drift Stack (presently 29 cm drift) Laser Upper fixed source • Used to study • Drift velocities • Drift lengths • Diffusion parameters • Energy loss (dE/dx) • Study impurities • Readout structures • Field cage design Lenses Lens Triple GEM Lower movable source Lab 2-86 in Physics C.Woody, Upgrades DC Meeting, 10/9/03

  4. Drift Cell Measurements Ar/CO2 (80/20) Ar/CF4 (95/5) 22% FWHM/mean Energy Resolution (Top 55Fe source) 28% FWHM/mean * Data o Garfield * Data o Garfield • Possible discrepency • Gas mixture uncertainty • 300 ppm O2 • 10-15 ppm H2O Drift Velocities (laser) C.Woody, Upgrades DC Meeting, 10/9/03

  5. Charge Distribution from Drift Cell(top source, 2 mm pad readout) Ar/CO2 (80/20) Ar/CF4 (95/5) s=1.2 mm s=1.7 mm pad number pad number Measured s=1.1 mm s=1.4 mm Simulation (N.Smirnov) pad number pad number C.Woody, Upgrades DC Meeting, 10/9/03

  6. GEM Foils from 3M 3M Microinterconnect Systems Division, Austin, TX In collaboration with Univ. Chicago (J.Collar) Roll-to-roll process Limited to 12” width Received 2 batches (50 each) of 10x10 cm foils C.Woody, Upgrades DC Meeting, 10/9/03

  7. Testing Small 3M Foils 80 mm (55 mm) holes spaced in a hexagonal pattern with 140 mm pitch (approx. same as CERN foils) Visually looks to be excellent quality 3 stage GEM with three 1” dia. 3M foils C.Woody, Upgrades DC Meeting, 10/9/03

  8. Comparison of Small Triple GEMS Ar/CO2 (80/20) CF4 3M GEMs give higher gain and have somewhat different slopes C.Woody, Upgrades DC Meeting, 10/9/03

  9. Electron Transfer Efficiency C.Woody, Upgrades DC Meeting, 10/9/03

  10. Gain Stability - Small 3M GEMs Ar/CO2 (80/20) CF4 We observe a large gain variation with the small 3M GEMs with time Time scales involved imply a possible charging effect in the foils (Gas: 35 ppm H20, <1ppm O2) C.Woody, Upgrades DC Meeting, 10/9/03

  11. Gain Stability - Small CERN GEMs in Ar/CO2 No large gain variations observed with small CERN GEMs C.Woody, Upgrades DC Meeting, 10/9/03

  12. Gain Stability - Large Foils C.Woody, Upgrades DC Meeting, 10/9/03

  13. TPC Prototype - To be built this year • Full size module • Tests field cage design • Tests materials to be used in • actual construction • Allows testing with cosmic rays • Provides structure on which to • design and study readout plane • Test bench for new readout • electronics C.Woody, Upgrades DC Meeting, 10/9/03

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