Date: Fri, 03 Sep 2004 12:07:30 -0500
From: Neven Simicevic
To: Mark Pitt
Cc: tony@phys.latech.edu, grimm@jlab.org, finn@jlab.org, jmammei@vt.edu,
nmorgan@vt.edu, carlini@jlab.org, mack@jlab.org, smithg@jlab.org,
opper@jlab.org, birchall@physics.umanitoba.ca, armd@jlab.org,
yl0094a@jlab.org, Neven Simicevic
Subject: Re: Qweak working group - next meeting
Parts/Attachments:
1.1 OK 96 lines Text
1.2 Shown 106 lines Text
2 11 KB Application
3 11 KB Application
4 322 KB Application
5 448 KB Application
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Dear Working Group,
I did some investigation into the collimator design and would like to
share some findings with you. To be brief here they are:
1. I abandoned the the primary collimator as the kinematics defining
collimator. I think the kinematics defined by this collimator is too
rough. We can achieve higher rates on the expenses on our kinematics,
meaning the angular acceptance and the Q^2 acceptance become too broad.
Also, Jim did detailed study of this collimator.
2. I split the second collimator in two. First part kinematics defining,
second part cleanup. Now we can define kinematics much better, have
high rates and very narrow angular and the Q^2 acceptance ( shown in two
figures attached to this mail). The sketch of the collimator is also
attached. There is of course possibility for an improvement here and mini
torus was not included.
3. The rate with such a collimator is 943 MHz, Q^2=0.0248 GeV^2. I
roughly scaled FOM using Jim's table and found it to be 0.582. I do not
have program to do as advanced error analysis as Jim can.
4. Detector width with this collimator is 16 cm and length 200-210 cm.
Also attached.
5. This collimator can be easily improved, the rates can be increased and
Q^2 shifted on the expenses of the detector size.
6. I did not do detailed background studies with this setup, but
preliminary results show there is no problem with the background.
Regards, Neven
Neven's attachments:
new_colim_det_shape.ps
new_colim_qq.ps
new_colim_rate.ps
new_colim_side_view.ps