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[Opal] Re: SBend Results and Questions

Chronological Thread 
  • From: Yi-Nong Rao <raoyn AT>
  • To: Andreas Adelmann <andreas.adelmann AT>
  • Cc: Norman Huang <norman-huang AT>, Rick Bartman <krab AT>, Thomas Planche <tplanche AT>, opal AT
  • Subject: [Opal] Re: SBend Results and Questions
  • Date: Thu, 17 Nov 2011 17:13:36 -0800
  • List-archive: <>
  • List-id: The OPAL Discussion Forum <>


Further to Norman's e-mail, I want to make it clearer as to what the issue is.

What he did was a simple test to OPAL: track a single particle through a 90 degrees
magnetic S-bender with the fringe field turned off. The initial X is -0.004m while initial
PX is 0. (Initial means at the entrance of the magnet.) The X,PX values were recorded
at each step of the numerical integration up to the exit of the magnet. As a result of
OPAL tracking, X vs S appears to a cosine curve as expected (please look at Page 3 of
Norman's summary "SBEND-results.pdf"), while PX vs S shows funny numbers near
zero instead of a sine curve (see Page 7). I don't understand this. We cannot figure out
why from your source code.

It makes no sense to track multiple particles if a single particle tracking does not give
correct result. We may have misunderstood something. Could you take a careful look at
Norman's input and output files and help us out?

Thanks in advance.


Norman Huang wrote:
Yi-Nong and I do not know how to interpret these SBEND results. Please take a look at my test cases summary. Attached are the OPAL input file (, Enge coefficient file (FAND1.T7), single particle tracking data (particleInfo_Fringe.txt, particleInfo_NoFringe.txt)

The 12 columns for the particleInfo files are:
Bx By Bz X_ref Y_ref Z_ref Px Py Pz X_local Y_local Z_local


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