Search found 38 matches

by GPenn
19 Dec 2019, 15:33
Forum: Bugs
Topic: Tracking issues in CSBEND elements in the presence of errors
Replies: 9
Views: 9540

Tracking issues in CSBEND elements in the presence of errors

Sorry for the poor timing of this post. I see several problems with the tracking in CSBEND elements that include error terms. I've been tracking particle through bends using specific errors, rather than only looking at rms quantities. First, ETILT does not seem to work properly. This seems related t...
by GPenn
06 Dec 2019, 19:29
Forum: Ring Tracking
Topic: how to model overlapping corrector magnets and focusing elements
Replies: 7
Views: 4156

Re: how to model overlapping corrector magnets and focusing elements

Thanks Mike, I appreciate the REFERENCE_CORRECTION=1 suggestion. It makes a big improvement for moderate values of N_KICKS. I am still confused about the sign convention for ETILT. A positive angle bend is making the coordinate system curve in the -x direction. If ETILT is acting in the same directi...
by GPenn
30 Nov 2019, 22:55
Forum: Ring Tracking
Topic: how to model overlapping corrector magnets and focusing elements
Replies: 7
Views: 4156

Re: how to model overlapping corrector magnets and focusing elements

Thank you for the explanation Michael. That helped a lot, and I am pretty happy with the comparisons between AT and elegant using 'straight' magnets. I am having issues with comparisons in bends involving ETILT, even involving a simple ideal bend magnet, which I think comes from how I am trying to t...
by GPenn
15 Nov 2019, 19:13
Forum: Ring Tracking
Topic: how to model overlapping corrector magnets and focusing elements
Replies: 7
Views: 4156

Re: how to model overlapping corrector magnets and focusing elements

I should add that I am doing this to match lattices constructed in Accelerator Toolbox. The fields of a given element can become quite complicated in AT depending on how errors and correctors are implemented. I'm working on a script to generate a nearly equivalent elegant lattice file.
by GPenn
14 Nov 2019, 20:32
Forum: Ring Tracking
Topic: how to model overlapping corrector magnets and focusing elements
Replies: 7
Views: 4156

how to model overlapping corrector magnets and focusing elements

I would like to model orbit correction elements which are overlapping more standard magnets. They don't have to be dynamically controlled. Is EKICKER the best way to combine a dipole kick with focusing fields if I do not want the kick to impact the coordinate system? It looks like I can't use separa...
by GPenn
28 Oct 2019, 23:16
Forum: General
Topic: serial version of elegant renumbers particleID values
Replies: 3
Views: 2455

Re: serial version of elegant renumbers particleID values

Sorry I was too quick to see a problem before, I was reading the output like a text file and missed that the particle order was just being shuffled - I guess whenever a particle gets lost, it trades places with the last valid particle. That means if I have 1000 particles and lose 2, the end of the p...
by GPenn
25 Oct 2019, 15:03
Forum: General
Topic: serial version of elegant renumbers particleID values
Replies: 3
Views: 2455

serial version of elegant renumbers particleID values

A lot of my post-processing revolves around picking an individual particle in a bunch and seeing its trajectory, or looking at lost particles and seeing where they started, etc. The only way I know how to do this is to use a WATCH element and track particles by their particleID. For Pelegant, this s...
by GPenn
01 Mar 2019, 14:33
Forum: Momentum Aperture
Topic: Is Momentum Aperture really deterministic?
Replies: 2
Views: 11374

Re: Is Momentum Aperture really deterministic?

Thank you for the information, Mike. I will try your way of scanning momentum offests. I was all set to go the opposite route and try going backwards lots of steps. For my ALS-U runs, I do use the RF acceleration and SYNCH_RAD=1. I had it in my head it would be simpler to give an example using SPEAR...
by GPenn
21 Feb 2019, 18:13
Forum: Momentum Aperture
Topic: Is Momentum Aperture really deterministic?
Replies: 2
Views: 11374

Is Momentum Aperture really deterministic?

Hi, This may seem like a philosophical question but I am having some substantive issues with calculating the MA for the ALS-U storage ring. This is a very nonlinear lattice with strong bends and sextupoles, not to mention that the fractional horizontal and vertical tunes are almost identical. I set ...
by GPenn
04 Jan 2019, 13:13
Forum: Bugs
Topic: Some confusing issues with insert_elements
Replies: 4
Views: 7594

Re: Some confusing issues with insert_elements

Hi Michael, Thanks, that did the trick. My workaround was to do a separate elegant run just to read in the nominal lattice, insert the elements, and save a revised lattice file using output_seq=1. With the new lattice I can still load in the same parameters file without a problem. I like your way si...