Email from Yongguang:
Date: Mon, 27 Sep 2004 15:07:19 -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: tomographic plots of photon background for Neven's collimator
Hi folks,
Attached are a few tomographic plots (similar to what Jim showed in
"May2003Talk.pdf") of photon background for
Neven's collimator. I used the Qweak.bash and Qweak.euclid file from
Juliette (I think Juiette got the bash
file from Jim and euclid file from Neven). I also used Richard Jones's
internal bremssatrahlung correction. 100k events
are simulated with 3 < theta < 16 degree and -15.5 < phi < 15.5
degree. The minitorus is turned off in the simulation.
As shown in the plots, significat amount of secondary photons are
generated at upstream face of the upstream half of
the Neven's collimator, as well as the upper edge of both the upstream
and downstream parts of the Neven's collimator.
As a comparison, I also attached Jim's "May2003Talk.pdf" here, which I
think it is for standard 8-8-22 Boston collimator.
The photon rate hitting the Cerenkov bar at Z=530 cm (cuts: 302 < x <
318 cm, -105 < y < +105 cm) is 0.0196 MHz, and
the mean Q^2 of the photons hitting the bar is 0.01351 GeV^2. No "hot
spot" of photon is seen on the bar.
Best regards,
Yongguang
********************************************************
* Yongguang Liang Tel: (757)269-5333 (office) *
* Trailer 11A Room 2 Email:yl0094a@jlab.org *
* Jefferson Lab *
* 12000 Jefferson Ave. *
* Newport News, VA 23606 *
********************************************************
Youngguang's attachments:
neven_juliette_collimator_side_view.gif
o_x_z_photon_neven_collimator.gif
o_x_z_photon_neven_collimator_large.gif
o_y_z_photon_neven_collimator.gif
May2003Talk.pdf