Skip to Content.
Sympa Menu

opal - AW: [Opal] example of parameter scan in opal

opal AT

Subject: The OPAL Discussion Forum

List archive

AW: [Opal] example of parameter scan in opal

Chronological Thread 
  • From: "Frey Matthias (PSI)" <matthias.frey AT>
  • To: opal <opal AT>, "piot AT" <piot AT>
  • Subject: AW: [Opal] example of parameter scan in opal
  • Date: Tue, 21 Apr 2020 11:52:04 +0000
  • Accept-language: de-DE, de-CH, en-US

Dear Philippe,

there's an example of the sampler in the manual

In order to do scans, it's best you set RASTER=TRUE in the SAMPLE command, especially if you want to do multi-dimensional scans. Fuhrtermore, make sure you do not have any RANDOM=TRUE in the

individual SAMPLING commands. The sampler has the possibility to evaluate objectives like the optimizer.

The sampler then writes the objective output to the JSON file.

I've never used this option, hence, I do not have an example at hand. But maybe somebody else has one.

When you defined the objectives (i.e. obj1, obj2, ...), you have to put them into a list OBJECTIVES = {obj1, obj2, ...} in the SAMPLE command.

I hope this helps.



Von: opal-request AT <opal-request AT> im Auftrag von Philippe Piot <piot AT>
Gesendet: Dienstag, 21. April 2020 13:32:57
An: opal
Betreff: [Opal] example of parameter scan in opal
Dear All,
  Does somebody could share an example of an opal input file demonstrating how to scan a parameter (e.g. a solenoid B field) and record some of the beam parameters at the end of the beamline. Right now I am doing this externally (with my own scripts) but I am wondering if this is possible with the sampler feature. Thank you,  -- Philippe.

Philippe Piot,
Northern Illinois University, Dept of Physics and
Northern Illinois Center for Accelerator & Detector Development
DeKalb, IL 60115, USA
Tel: 815 753 6473, Web:

Argonne National Laboratory, Advanced Photon Source
Accelerator System Division
Lemont, IL 60439, USA
Tel: 630 252 2415, Web: 

Archive powered by MHonArc 2.6.19.

Top of Page