The OPAL Discussion Forum

["Frey Matthias (PSI)" <matthias.frey AT psi.ch>]

Dear Philippe,

there's an example of the sampler in the manual

http://amas.web.psi.ch/opal/Documentation/master/OPAL_Manual.html#_example_input_file_2

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.

http://amas.web.psi.ch/opal/Documentation/master/OPAL_Manual.html#sec.optimiser.opt-pilot-commands

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.

Best,

Matthias

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Von: opal-request AT lists.psi.ch <opal-request AT lists.psi.ch> im Auftrag von Philippe Piot <piot AT nicadd.niu.edu>
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,
https://www.niu.edu/advanced-accelerator-randd/
Northern Illinois University, Dept of Physics and
Northern Illinois Center for Accelerator & Detector Development
DeKalb, IL 60115, USA
Tel: 815 753 6473, Web:  http://www.physics.niu.edu/physics/

Argonne National Laboratory, Advanced Photon Source
Accelerator System Division

Lemont, IL 60439, USA

Tel: 630 252 2415, Web:  https://www.aps.anl.gov/Accelerator-Systems-Division