CDC wiggle wire positions

Started looking at 3 wires, straw 17 (central) which is one of the better resolution straws, and then straws 7 and 5 which are worse.

Schematic of prototype with straw numbers

Resolution before moving wire positions

Wiggled wire positions in a 9x9 grid for wires in the order 17, 7, 5, starting with box width 160um (9 boxes in the grid) and halving box size for each step, down to 5um. Minimized fitted gaussian width/height. 1e5 cosmic events total. Detector at 45 degrees.

Before (top) and after (bottom)

straw 17 (channel 20)

straw 7 (channel 10)

straw 5 (channel 8)

Oops! The above used Garfield tables for the wrong HV. Corrected versions are/will be below.
The resolution peak has mean>0 when the tzero is too large and so the net drift time is too small. The resolutions are double-peaked if the position is wrong. Errors in both cause the width to increase.

Before (top) and after (bottom) with tzero = straight line fit + 6ns

straw 17 (channel 20)

straw 7 (channel 10)

straw 5 (channel 8)

Before (top) and after (bottom) with tzero = straight line fit + 7ns

straw 17 (channel 20)

straw 7 (channel 10)

straw 5 (channel 8)

After 2 iterations of moving all the straws

2 sets of iterations of moving all the straws with tzero = straight line fit + 6ns,

Black:original Pink:1 set of iterations Blue: 2 sets of iterations