Elegant users forum

Hi,

I am running the optimizer to perform a transverse match in a short beamline. In the .ele file I am specifying that the beam be generated from an sdds file:

&sdds_beam
input="BeamIN.sdds",
&end

When I then try to run the optimizer, it appears that Elegant successfully makes an initial pass through the beamline, but then halts with the error/warning message:

No particles left in input file(s)
error: unable to get beam for tracking (is file empty or out of pages?)

Using a "&bunched_beam" to define a fictitious beam (rather than read in a distribution) does not result in any errors. Is one prohibited from reading an external distribution while using the optimizer? I really would like to read in a distribution.

Thanks for the help!

Chris,

This can be fixed by adding the following to your sdds_beam command: reuse_bunch = 1. By default, elegant processes each "bunch" in the sdds file just once. This doesn't make much sense for optimization, admittedly.

This isn't a problem when you use bunched_beam, because bunched_beam behaves differently: it (by default) reuses the beam again and again, as long as needed.

--Michael