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**From**: "Pogue Nathaniel Johnston (PSI)" <nathaniel.pogue AT psi.ch>**To**: opal <opal AT lists.psi.ch>**Subject**: [Opal] Distributions**Date**: Tue, 23 Feb 2016 09:49:17 +0000**Accept-language**: en-US, de-CH**List-archive**: <https://lists.web.psi.ch/pipermail/opal/>**List-id**: The OPAL Discussion Forum <opal.lists.psi.ch>

Hello,

I have been looking at various distributions and I have been having some difficulty understanding the method OPAL is calculating the distributions.

First off, in what frame is the input for the distribution to be written? From what I can see it appears that the distribution is always inserted in the global frame, but at times it appears to correlate more to the local frame.

The second question is what is the definition of the frames? I know OPAL T and OPAL CYC might be different, so please for OPAL CYC only.

From what I have seen from a few runs is

local frame: x radial, y vertical, z longitudinal

global frame: x radial, y 90 degrees to x, z vertical.

Are these definition correct?

**From the inputed distribution how does OPAL calculate the local and global bunch information?**

This is the main question, but I have other supporting questions below as well.

I inserted a binomial distribution in to the a cyclotron with specified correlation functions. They seems to be relatively preserved, all values hovered around 1e-6, then I inserted 0 for all correlation functions and i obtain correlation in the bunch
information larger than 1e-4.

Lastly and most strange is that I changed the sigma px, py, pz by a factor 3 to 4 (values 44 ,112 ,77 in eV if I am not mistaken) and this caused my bunch to extract 10 turns earlier and with 10 MeV less energy. Though px,py,pz are larger, 112 eV vs 25
eV originally, should not result in such dramatic change.

So I would greatly appreciate it if someone could take a look at this and give me some feedback.

Nate

**Dr. Nathaniel J. Pogue**

**PSI Fellow**

Paul Scherrer Institut

WBBA/215 CH-5232 Villigen PSI

Office Phone xx41 56 310 51 95

**[Opal] Distributions**,*Pogue Nathaniel Johnston (PSI), 02/23/2016*

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