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sddsmatch (issues?)

Posted: 22 Aug 2011, 14:10
by Philippe Piot
Hi,

I am using sddsmatch to perform a series of matching as part of an optimization algorithm. I just noticed some awkward behavior, rematching, e.g., the horizontal Courant-Snyder parameters messes the transverse horizontal emittance, and for some cases the parameter I am trying the set do not reach the value. Here is an example:

1 *** I first analyse the distribution (attached) distexmple.sdds
[piot@node1 August2011]$ sddsanalyzebeam distexmple.sdds -pipe=out | sddsprintout -pipe=in -column=pAverage -column=alphax -column=betax -column=enx -column=alphay -column=betay -column=eny -column=Ss -column=Sdelta -column=s56 -column=s55
warning: no column matches Ss
Printout for SDDS file stdin

pAverage alphax betax enx alphay betay eny Sdelta
s56 s55
m m m m
s s$a2$n
------------------------------------------------------------------------------------------------------------------------
1.222213e+01 1.086602e+02 2.163274e+01 7.808927e-12 1.296249e+02 2.581368e+01 8.707101e-12 3.676671e-04
7.284417e-18 3.925626e-28

2 *** Now I rematch the alpha_x and beta_x of distexmple.sdds to (70,30)
[piot@node1 August2011]$ sddsmatchtwiss distexmple.sdds tmp1 -xPlane=alpha=70,beta=30

3 *** Finally I analyse the rematched distribution output
[piot@node1 August2011]$ sddsanalyzebeam tmp1 -pipe=out | sddsprintout -pipe=in -column=pAverage -column=alphax -column=betax -column=enx -column=alphay -column=betay -column=eny -column=Ss -column=Sdelta -column=s56 -column=s55
warning: no column matches Ss
Printout for SDDS file stdin

pAverage alphax betax enx alphay betay eny Sdelta
s56 s55
m m m m
s s$a2$n
------------------------------------------------------------------------------------------------------------------------
1.222213e+01 1.936840e+01 8.283201e+00 2.827056e-11 1.296249e+02 2.581368e+01 8.707101e-12 3.676671e-04
7.284417e-18 3.925626e-28


****
I notice the target (alpa,beta)=70,30 m are not reached and the emittance enx blows up.

Thank for any suggestion. (I attached the distexmple.sdds ). -- Philippe.

Re: sddsmatch (issues?)

Posted: 22 Aug 2011, 14:42
by michael_borland
Philippe,

You should give the -correctedOnly option to sddsanalyzebeam. Otherwise, the beta and alpha values will include any dispersive beam size and divergence that might be present. Alternatively, look only at the "corrected" values (e.g., betacx).

--Michael