Can you please tell me what I'm doing wrong here?
We suspect that there is dispersion leakage that is affecting the X emittance, so we wanted to try out the -includeDispersion option. Assuming sddsemitproc removes the dispersion contribution, I would expect a smaller emittance. Rather than larger.
One mistake may be the dipole that I included in the line for the -includeDispersion option. The matrix elements start_from that dipole. Should I start farther upstream?
If you're willing to look into this, email me for other relevant files. The forum wouldn't let me attach > 3
Thanks.
Michele Joyce
TJNAF
sddsemitproc including dispersion
Moderators: cyao, michael_borland
sddsemitproc including dispersion
- Attachments
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- input.sdds
- This sdds file is what's passed to sddsemitproc WITHOUT the -includeDispersion option
- (5.87 KiB) Downloaded 145 times
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- input.dpp.sdds
- This sdds file is what I'm passing sddsemitproc and using the -includeDispersion option. It includes R16 and R36
- (7.16 KiB) Downloaded 157 times
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- Posts: 1933
- Joined: 19 May 2008, 09:33
- Location: Argonne National Laboratory
- Contact:
Re: sddsemitproc including dispersion
Michele,
Sorry for the delay in responding.
The -includeDispersion option is not reliable. It is actually disable in the most recent release. It attempts to determine the energy spread, but doesn't succeed well even in ideal cases. I think the problem is degenerate because the energy spread is a fixed quantity.
My suggestion is to subtract the dispersion contribution (in quadrature) from the beam sizes before. This requires that you know the energy spread already from a separate measurement.
--Michael
Sorry for the delay in responding.
The -includeDispersion option is not reliable. It is actually disable in the most recent release. It attempts to determine the energy spread, but doesn't succeed well even in ideal cases. I think the problem is degenerate because the energy spread is a fixed quantity.
My suggestion is to subtract the dispersion contribution (in quadrature) from the beam sizes before. This requires that you know the energy spread already from a separate measurement.
--Michael
-
- Posts: 1933
- Joined: 19 May 2008, 09:33
- Location: Argonne National Laboratory
- Contact:
Re: sddsemitproc including dispersion
Michele,
It might work if you have significant dispersion at the location of one of the quadrupoles you vary.
--Michael
It might work if you have significant dispersion at the location of one of the quadrupoles you vary.
--Michael
Re: sddsemitproc including dispersion
Thanks for the reply. We'll try the subtraction method.