The OPAL Discussion Forum

["Snuverink Jochem (PSI)" <jochem.snuverink AT psi.ch>]

Dear Simon,

 

The .data file can be used to define certain constants that are used in the .tmpl file, similar to design variables but constant.

See e.g. here, where the same scheme is used with a different tool: https://gitlab.psi.ch/OPAL/src/wikis/runOPAL

However, this is not strictly needed for the sampler, just add an empty file with the correct name to your directory:

 

touch /media/sf_Seafile_OPAL/example_sampler/example_sampler_drift.data

 

Sorry for this, we are aware and there is an outstanding issue regarding this.

 

Hope that helps,

best regards,

Jochem

 

From: opal-request AT lists.psi.ch <opal-request AT lists.psi.ch> On Behalf Of Dr. Simon Friederich
Sent: Montag, 17. Februar 2020 08:56
To: opal AT lists.psi.ch
Subject: [Opal] Exception using sampler

 

Dear all,

Please let me shortly introduce myself:
My name is Simon Friederich. I am working at the institute of nuclear physics in Mainz (Germany) and I have just recently started simulating with OPAL. My goal is to simulate the low-energy beam apparatus of our upcoming Mainz Energy-recovering Superconducting Accelerator (MESA).

I gathered some experience starting with a simple example: I sent a gaussian distributed bunch through a 1m drift (electrons, 100keV, I=1mA) and watched the emittance growth in particular.

My next step was to use the 'sampler' and change some variable (e.g. the CUTOFFR parameter of my injected distribution). But I get the following exception message leading to a simulation stop:

OPAL{0}> opal sampler.in --inputfile=example_sampler_drift.tmpl --outfile=samplerout --outdir=samplerout --num-masters=1 --num-coworkers=1 --restartstep=-2147483648 --jsonDumpFreq=18446744073709551616 --nsamples=1 --simtmpdir=/media/sf_Seafile_OPAL/example_sampler/samplerout --templates=/media/sf_Seafile_OPAL/example_sampler/. 

  ✔ 1 objectives

  ✔ 1 dvars

  0 (PID: 1686) ▶ Pilot

  1 (PID: 1687) ▶ Sampler

  2 (PID: 1688) ▶ Worker

Warning: argument "one-pilot-converge" not found! Using default value (0).

  3 (PID: 1689) ▶ Worker

Exception while running simulation: The data file 'example_sampler_drift.data' 

     doesn't exist in directory '/media/sf_Seafile_OPAL/example_sampler'

Stop Pilot..

OPAL{0}> * End of input stream "sampler.in".

Stop Worker..

Stop Sampler..

Stop Worker..

I have tested the "example_sampler_drift.tmpl" with a fixed value of CUTOFFR and
it runs through. I get the results within the 'data' directory. No *.data file though.

Then I tried the example from https://gitlab.psi.ch/OPAL/Manual-2.2/blob/master/sampler.asciidoc but it prints out the same exception message:
Exception while running simulation: The data file 'Ring.data' doesn't exist in directory '/media/sf_Seafile_OPAL/example_sampler_opalwiki'

Is the *.data-file something specific coming from the sampler?
Do you have an idea of what I am missing here?

Thank you very much in advance.
Best regards,
Simon

-----------------------------------

Dr. Simon Friederich

Helmholtz-Institut Mainz

Collaboration B/ACID

Johannes Gutenberg-Universität Mainz

Staudingerweg 18

55128 Mainz, Germany

phone: +49 (0)6131 39-23160

E-Mail: sifriede AT uni-mainz.de

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