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How to calculate emittance
Posted: Fri 30 Jan 2026 17:25
by hanxj
Dear author
I would like to know what formula was used to calculate the value of Xmax in the circled part of this picture. If the reference is made to the circled part in the second figure, this calculation result is incorrect.
Re: How to calculate emittance
Posted: Mon 2 Feb 2026 18:43
by Didier
Dear Sir,
Please note that what is plotted is the total size, not the rms size (see image below) and the rms beam size = sqrt(Exxp_nn*bet). Exxp_nn is the rms unnormalised emittance, the one you are pointing to is the normalised one.
- emit.png (242.34 KiB) Viewed 548 times
Regards,
Didier
Re: How to calculate emittance
Posted: Fri 13 Feb 2026 04:16
by hanxj
However, even when the button click is replaced with the calculated maximum value of X based on the rms size, it still does not match the result obtained from this formula. Could it be that some additional factors have been included in the calculation?
Re: How to calculate emittance
Posted: Mon 16 Feb 2026 10:24
by Didier
Dear Hanxj,
On my side, using you beam parameters, I got SizeX_rms=5.53 mm. Please send me your project files, something is wrong, I'll check for you.
Regards,
Didier