Comparison of resolution of the cone geometry and the plane geometry.
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I threw 5 GeV muons at phi=3.75° (this is in the middle of a piece of silicon), around various angles theta (12-28°, see table), with a spread of 2°. 100 tracks/event, 19 events each. Events are processed through PISA, output files ancsvx_150_xx.root for the flat planes, ancsvx_151_xx.root for the cones, where xx is the value of theta.

Columns 2,3,4 are for the flat endcap geometry, columns 5,6,7 for the cone-shaped endcaps. Resolutions are sigmas of gaussian fits do delta-z distributions. 'Perfect tracking' means a line is drawn through the pisa coordinates in the first and last plane hit. 'Integerized' means the hit points are moved to the center of a 50 um strip. Most tracks see 4 planes, but at the highest angles you can see from columns 2 and 5 that some tracks see less than 4 planes.

  flat cones
theta
(degrees) 		#4 / #3 resolution
perf. tracking 		resolution
Integerized 		#4 / #3 resolution
perf. tracking 		resolution
Integerized
12 1090/25 259 299 1159/0 280 332
16 1900/00 217 243 1900/0 229 269
20 1900/00 156 179 1900/0 167 206
24 1880/15 173 191 1900/0 180 200
28 1820/70 151 177 1550/300 166 183




There is not a lot of difference at this level. I think the 'bump up' of the resolution at 24° has to do with the mass of the barrel pixel layer, which is traversed for track with theta>22° when coming from z=0.

The thin blue line scales as 1/sin(theta).



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Last update 24 Feb 06 - HvH
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