Email from Jim:

From birchall@physics.umanitoba.ca Fri Sep 17 14:06:30 2004
Date: Fri, 17 Sep 2004 11:17:42 -0500
From: Jim Birchall 
To: Yongguang Liang 
Cc: Juliette Mammei , Roger Carlini ,
     Klaus Grimm , Mark Pitt ,
     Neven Simicevic , Greg Smith ,
     Tony Forest , Norman Morgan ,
     Mike Finn , Shelley Page ,
     David Armstrong , Dave Mack ,
     Allena Opper ,
     Richard Jones 
Subject: Re: My simulation results for Inelastics with the '10-8-22 Boston
    collimator'

Yes, Richard Jones's updated gukine.F may cause part of the difference. 
The value of Q^2 I had for the 10-8-22 Boston collimator was for 
electrons above 1000 MeV, and no other cut, as we'd decided a few 
meetings ago. If I put a cut from 295 to 310 cm across the width of the 
bar (mini-torus off) the average weighted Q^2 drops from 0.03163 to 
0.02799 and the maximum Q^2 drops from about 0.082 to about 0.068. The 
energy cut makes little difference.

Jim

On 17 Sep 2004, at 10:13 am, Yongguang Liang wrote:

> Hi Jim /et.al/,
>
> I did a  similar simulation using 10-8-22 Boston collimator for 
> elastic and inelastic (reac 3,  e+p -> e + n + pi+; reac 4, e + p -> e 
> + p + pi+ + pi-;  reac 5, e + p  -> e + p + pi0;)  processes. Attached 
> are two plots I got. The first one shows the x and y positions where 
> the elastic electrons (black dot) and inelastic electrons (green dot 
> for reac 3, red dot for reac 5) hit the focal plane at Z=530 cm, the 
> rectangluar area within the lightblue line represnts where a Cerenkov 
> bar (200 cm long  x 16 cm wide) may locate. No inelastic electron from 
> reac 4 was found hitting the focal plane. All simulations are done 
> with 100k events. In the second figure, the Q^2 distributions for 
> these three reactions are ploted. The mean Q^2 for elastic process 
> that I got is smaller than Jim's. I got 0.02613 and Jim's plot shows 
> 0.03163. The possible reason is that I use Richard Jones's gukine.F
> (see Richard's  email on 08/30/2004) which counts the energy loss of 
> electron due to the pre-scattering bremsstrahlung of beam particle in
> target upstream of scattering vertex. But I did not use Rcichard's 
> internal correction and the new physics event generator in the 
> simulation.
>
>
> Best regards,
>
> Yongguang
>