The OPAL Discussion Forum

[Yi-Nong Rao <raoyn AT triumf.ca>]

Andreas,

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.

Yi-Nong


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 
> (qf.in), 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
>
> Regards
> Norman