Email from Roger:

Date: Fri, 01 Oct 2004 16:08:02 -0400
From: Roger D. Carlini 
To: Juliette Mammei , Yongguang Liang ,
     Dave Mack , Mark Pitt ,
     Jim Birchall , Klaus Grimm ,
     Neven Simicevic , Greg Smith ,
     Allena Opper , Tony Forest ,
     Norman Morgan , Mike Finn ,
     David Armstrong ,
     Shelley Page ,
     Richard Jones 
Cc: carlini@jlab.org
Subject: Collimator/quartz optimization

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Hi Folks:

The pdf's attachments in the previous message were too large for some email addresses. They are much smaller now. Sorry 
for the duplication.

I took Juliette's plots from yesterday for Neven^Òs ^Ósculptured^Ô and "unsculptured" downstream collimator and 
superimposed 15 and 18 cm wide quartz bars with a tilt angle of 3 degrees just to see what they actually look like. See 
attached pdf files. If we were to use only a moderately "sculptured" collimator to suppress the large phi large theta 
events then the combined effect might be very clean.

I suggest an algorithm to converge to an optimum collimator shape:

First select several bar sizes and shapes.

Then generate a contour plot at the z location of the collimator for each bar selection which contains the ratio of 
"elastics/in-elastics" for events which hit the quartz. Select a contour to give us the suppression factor desired. Then 
model this shape in GEANT to estimate the edge scraping component. Cut the collimator holes to the shape associated with 
the selected bar.

Best Regards

Roger



Roger's attachments:
NevensSculptured.pdf
NevensUnsculptured.pdf