From sachs@physics.carleton.ca Thu Jul 22 08:56:23 2004
Date: Wed, 21 Jul 2004 11:50:53 -0400 (EDT)
From: Kirsten Sachs <sachs@physics.carleton.ca>
To: Ronald Dean Settles <settles@mppmu.mpg.de>
Subject: summary of talk

Hi Ron,

here is a short version of what I said:


Old results on track resolution of GEM TPC -> NIM
Ar:CO2 (90:10), direct charge, 2mm wide pads
@ very small drift: resolution degraded due to large pads
@ large drift dist.: resolution worse than expected from
  diffusion in drift volume (~30 - 40%)

Our last results were presented in Paris:
Track resolution of a TPC with charge dispersion on a resistive anode,
Ar:CO2 (90:10), C_D=0.22 um/sqrt(cm), 2mm wide pads
small transverse diffusion like in a magnetic field.
@ small drift dist.: good resolution of 72 um
@ large drift dist.: consistent with diffusion
Had to correct ~100um bias due to inhomogenities in resistivity/gap


NEW:
Cross-check with
P10, C_D=0.56 um/sqrt(cm)  and  Ar:CO2 (80:20), C_D=0.16 um/sqrt(cm)
With very wide PRF (i.e. P10) very sensitive to inhomogenities
in resistivity/gap (= RC time constant), difficult to correct bias.

Monte Carlo simulation with charge dispersion.
Nice agreement with data.
Good tool for studies and development of e.g 2 track separation,
optimisation of pad width - charge width.

Results will be presented in Victoria.


Ciao,
        Kirsten


 _/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/
 _/ Carleton University          sachs@physics.carleton.ca
 _/ Dept. of Physics           Office: Herzberg Bldg. 2458
 _/ Ottawa, Ontario             Tel: 613-520-2600 ext:1567
 _/ K1S 5B6, Canada                      Fax: 613-520-7546