The OPAL Discussion Forum

["Kuske, Bettina" <bettina.kuske AT helmholtz-berlin.de>]

Hi Simon,

 

can you please send your input file, so we can have a look at it?

To my knowledge, the sampler does not work for a single variable.

Try if it works for two variables, if yes, that was the problem.

If no, send your input file.

 

Have a nice day,

Bettina

 

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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