The OPAL Discussion Forum

[Nicole Neveu <nneveu AT hawk.iit.edu>]

Hello,

I don't know about the cyclotron specific issues, but I noticed a similar frequency issue when I started using 1.9.

My issue turned out to be with the BCURRENT. I needed to use Hz to calculate this instead of MHz:

BFREQ = Frequency [MHz]

BCURRENT = Charge [C] * Frequency [Hz]

I've switched to 2.0 and these definitions still working for me in OPAL-T.

​Good Luck,

Nicole

On Mon, Jun 18, 2018 at 11:33 AM, Anastasiya Bershanska <nastya AT mit.edu> wrote:

Hello,

I’m trying to use OPAL 2.0 for running simulations and have questions about the conversion of input files from 1.6 to 2.0 as well as output standard. Is the output now in [m] instead of [mm]? What is the relationship between units of SLPTC in CYCLOTRON (OPAL 1.6) and SLPTC in TRIMCOIL (OPAL 2.0)? Also, do you have a working example/tutorial/test for OPAL 2.0 (i.e. new input files)?

The unexpected changes that I’ve noticed are:

• BFREQ in BEAM seems to be in MHz in both the old and the new OPAL (inconsistent with release notes for OPAL 2.0). Other frequencies are in MHz (both OPAL 1.6 and OPAL 2.0) and the same values are used in example input files for FREQ in RFCAVITY and BFREQ in BEAM. If the value for BFREQ in 1.6 input file is multiplied by 1e-6, OPAL 2.0 throws an error "The particle is out of the region of interest" in ParallelCyclotronTracker. Is BFREQ units an old bug that got fixed or a new bug?
• Output file for OPAL 2.0 seems to be in [m] while OPAL 1.6 is in [mm]. Is that a bug or a feature? Should it be documented somewhere?
• Trim coils are now a separate element TRIMCOIL with slightly different units for inputs: MBTC in [kG] and SLPTC in [kG/mm] are replaced by BMAX in [T] and SLPTC in [1/mm] (should probably be mentioned in release notes). Should SLPTC in TRIMCOIL be in [T/mm]?

I’ve also attached new cyclotron2.in that I’ve changed to work with OPAL 2.0 (see Cyclotron example). The output is consistent with the example online (resulting plot where cyclotron2.gpl takes in m instead of mm), so I wonder if all changes are correct, SLPTC in [T/mm] and BFREQ (unchanged) in particular.

- Anastasiya