Email from Yongguang:

From yl0094a@jlab.org Thu Sep 23 11:34:54 2004
Date: Mon, 20 Sep 2004 13:44:20 -0400
From: Yongguang Liang 
To: Mark Pitt 
Cc: Roger Carlini , Jim Birchall ,
     Juliette Mammei , Klaus Grimm ,
     Neven Simicevic , Greg Smith ,
     Allena Opper , Tony Forest ,
     Norman Morgan , Mike Finn ,
     David Armstrong ,
     Shelley Page , Dave Mack ,
     Richard Jones 
Subject: Re: Qweak working group - previous/next meeting

Hi Mark/ et.al/,

The simulation results I sent out last Friday is for standard 8-8-22 
Boston collimator, NOT the 10-8-22 Boston collimator. Sorry, it is my 
mistake.

Here is the elastic rate, mean Q^2, and FOM  I got when simulating 100k 
events with Richard's new code for standard 8-8-22 Boston collimator.

1) Considering the pre-scattering bremsstrahlung of beam particle in 
target upstream of vertex only,

elastic rate = 555 MHz, mean Q^2 = 0.02641, FOM = rate*Q^4 = 0.387

2) Considering the pre-scattering bremsstrahlung of beam particle in 
target upstream of vertex, and the correction of outgoing electron 
energy for internal bremsstrahlung,

elastic rate = 475 MHz, mean Q^2 = 0.02653, FOM = rate*Q^4 = 0.334

The rate is calculated for a  2.0 m long bar at Z=530 cm with x width 
cut 302< x < 318 cm. and the electron energy > 1000 MeV. I did not used
Richard's new event generator, but use the old event generator instead 
(set ISOT=1 in bash file).

Attahced is a plot showing the x projection, Q^2 and theta distribution 
of the above two cases (the left three panels are for case 1, and the right
three panels are for case 2).

Best regards,

Yongguang


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comparison.ps