Influence of cathode shifted on 50 micron from its ideal position on
the gas gain and on xt-relation was estimated by GARFIELD. This part presents
dependence of gas gain  from position of cathodes.
 	Estimations were made for our 4 mm chamber geometry for pure DME at
T=293K and P=760 Torr. Cathode high voltage is set to -1850V. Cathode planes
are placed at y=2.00mm and y=-2.00mm, wire plane at y=0. Central wire (with
diameter 15 micron) is placed in the (0,0).
	Command "check avalanche range 1.0  5.0e+5 from x, y" was used for
estimations in SIGNAL section of GARFIELD. Avalanche type is Polya-Townsend.
GARFIELD calculates number of pairs generated by single electron started from
point (x,y).
	Calculations were made for 5 starting points for each position of
cathodes. Positons of cathodes, starting points and average gas amplifications
are shown in the table. Attached file shows generated avalanche distribution.

                                Cathodes positions
                  -----------------------------------------------------
Startig point:     y=+2.00mm     y=+2.00mm      y=+2.00mm     y=+2.05mm
                   y=-2.00mm     y=-2.05mm      y=-1.95mm     y=-1.95mm

from (0,  0.15)   1.404*10**5   1.331*10**5    1.492*10**5   1.391*10**5
from (0.1, 0.1)   1.390*10**5   1.314*10**5    1.477*10**5   1.385*10**5
from (0.15,  0)   1.384*10**5   1.304*10**5    1.477*10**5   1.387*10**5
from (0.1, 0.1)   1.387*10**5   1.299*10**5    1.485*10**5   1.407*10**5
from (0, -0.15)   1.399*10**5   1.305*10**5    1.497*10**5   1.421*10**5

Wire surface      410.5 kV/cm   409.2 kV/cm    411.9 kV/cm   410.6 kV/cm
field




--------------------------------------------------------
Yuri Davydov (davydov@triumf.ca)       (604) 222-1047 ext.6198
TRIUMF  			  FAX  (604) 222-1074
4004 Wesbrook Mall
Vancouver,  BC
Canada   V6T 2A3

Description: Fig.1 , Filename: avalanche.ps

Created for the The Center for Subatomic Research E614 Project Projects Page.

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