Hi Eugene,
As I understand things the agreement at forward angles is quite
good. Where the reconstruction has problems is around 40-50 degrees
and with softer momenta say 500-600 MeV. If you could simulate a
track like that it would be useful.
The other effect I wanted to ask is whether or not you are using
the ideal positions for the BLAST coils or if you were able to get
the actual positions which are shifted by about 10 mm?
Cheers,
Douglas
26-415
M.I.T. Tel:
+1 (617) 258-7199
77 Massachusetts Avenue Fax: +1
(617) 258-5440
Cambridge, MA 02139, USA E-mail:
hasell@mit.edu
On May 13, 2005, at 7:47 PM, Eugene J. Geis wrote:
> .... Don't know what happened with the files... One more time
> with the old
> message.....
>
> The file "Contour Field and Trajectory.png" is an overhead view of
> the field in
> the ZX BLAST frame. It is a contour map of the field. There is a
> blue line
> that represents a simulated electron's trajectory that came out of
> the origin
> at a polar angle of 25 degrees and energy 850 MeV.
>
> The track has been simulated but stepping 1 cm at a time 350 times
> through the
> field. The file "Electron_Track_Mag.ps" is 2 plots of the
> deviation of the
> exact same particle, i.e. same initial conditions, at each step in "No
> Shielding" and "Shielding" situations. The deviations plotted are
> the overall
> magnitude difference of the position at each step and the overall
> magnitude
> difference of the momentum at each step. The maximum deviation
> proves to be
> 0.16 cm at a point outside the field and approximate 2.3 MeV
> different at the
> exit from the field. This is well below our extracted offsets and
> momentum
> resolution.
>
> There are also three plots included which are plots of the Flux
> Density in the
> Y direction. They are labeled as "Field_to_CC0_Done.ps",
> "Field_to_CC1_Done.ps", and "Field_to_CC2_Done.ps". The fields in
> these three
> plots have been plotted along a line stretching from the origin to
> the center
> of
> the three respective Cerenkov boxes. In each file, there are two
> plots. The
> plot on the left is a superposition of the field simulations with
> (in blue) and
> without shielding (in red). On the right, the ratio at accessible
> bins is
> plotted (Shielded divided by NOT Shielded). The x-axis is the
> length over the
> path of our plot in centimeters (the path from the origin to the CC
> box). Some
> of the deviations in the first 100 centimeters of each plot may be
> results of
> the Finite Element meshing or they may be real. Either way, at the
> deepest
> center of our field, the ratio never seems to differ by more than
> 2%. There is
> a consistent dip in each as you approach the CC boxes but the field
> is rapidly
> approaching zero as this dip becomes more pronounced and this will
> not affect
> our reconstruction since the electron would have already punched
> through the
> WC's at this point.
>
>
> In conclusion, TOSCA shows no major deviation that would come close
> to the
> kinematical problems in reconstruction. Within the first 200 cm's
> along the
> simulated path of an 850 MeV electron (slightly higher than what is
> actually
> there, my apologies...), we remain within the width of our 200 micron
> resolution in the WC's.
>
> Michael suggested attempting to corroborate the present field map
> with new
> TOSCA calculations. I would like to know what the format of the
> field map is
> and where to find it. I can resume working on something like this
> in about 3
> weeks when I'm done with the stress of moving and feeling settled
> back in
> Arizona. That is, as long as Ricardo has purchased the program...
>
> I'm leaving on Monday. Hope to see you all again at the next
> collaboration
> meeting.
>
> eugene
>
>
> ----------------------------------------------------------------------
> ----
> Eugene Geis
> PhD Student, Physics Department, ASU
> Research Affiliate, MIT-Bates Laboratory of Nuclear Science
> eugene.geis@asu.edu
>
> ----- End forwarded message -----
>
>
>
> ----------------------------------------------------------------------
> ----
> Eugene Geis
> PhD Student, Physics Department, ASU
> Research Affiliate, MIT-Bates Laboratory of Nuclear Science
> eugene.geis@asu.edu
> ----------------------------------------------------------------------
> ----
> http://quickreaction.blogspot.com
>
> <Contour Field and Trajectory.png>
> <Electron_Track_Mag.ps>
> <Field_to_CC0_Done.ps>
> <Field_to_CC1_Done.ps>
> <Field_to_CC2_Done.ps>
>
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