The OPAL Discussion Forum

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

Hi Dou,

The "p_{r}^2 > p^{2}" error happens when there is no convergence to a closed orbit.

First of all, does the orbit look correct without the closed orbit finder?

Then I noticed that your initial energy and radius are very small. It is more difficult to find a closed orbit for small energies and it might not even exist.

 

Try to increase the FMLOWE and RINIT (or I think similarly RGUESS in the distribution) to larger values, perhaps starting somewhere close to FMHIGHE. Hopefully the larger orbits will converge.

If that doesn't help, you can send me the magnetic field map, and I'll have a look.

Best regards,

Jochem

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From: opal-request AT lists.psi.ch <opal-request AT lists.psi.ch> on behalf of Dou Guoliang <douglas610322 AT 163.com>
Sent: Tuesday, May 26, 2020 4:22:55 PM
To: opal
Subject: [Opal] Tune calculation in OPAL

 

Hi ,all

 I got stuck in  tune calculation  for our  heavy-ion cyclotron.

I modified some important parameters in the "cyclotronTune-2-1.in",which is from "https://gitlab.psi.ch/OPAL/src/wikis/Cyclotron" . And when I run it ,it got stuck like the picture I attached. When I run the original input file ,I got right output files.

I noticed it says "p_{r}^2 > p^{2}" ,. I checked the pr0 value I inserted, and it is right. And I changed the value of pr0 to 0 , it got the some error like the picture.

I don't know where was wrong in the input file . Did I lost  modifying some important parameters ? So , I attached my input file and the original input file.

Sincerely,

Dou