CEA Codes forum

I am currently making a matching section between one kind of accelerating cavity (A) to the other kind of accelerating cavity (B). For this, I first found the matched twiss parameters of the B cavity with some lattice structure. And for actual matching part, i use DIAG_TWISS.
In DIAG_TWISS command, a value for betZdp/p is needed in mm/ pi mrad. normally in finding matched parameter, tracewin returns betZZ' value (in mm/pi mrad). I also can get betZdp/p but in mm/pi %.
So here I am bit confused exactly what longitudinal beta value to put. My code shows a matching criterion value of ~e-15. And I think it is matching very well. However, with this calculated matching section, i got bit different value of betZdp/p.
Could you explain me the longitudinal beta in DIAG_TWISS?

Thank you.

Seunghyun

Dear Seunghyun,

betZdp/p(mm/pi mrad) = betZdp/p(mm/pi %) / 10

Another point, I don't know your structure file, so I don't know if it's possible in your project, but I suggest you replace DIGA_TWISS by several DIAGs such as DIAG_DSIZE2 and DIAG_DSIZE3 located on the first 5 or 6 periods. Firstly, it is more realistic and secondly, it does not depend at all on emittance.

Regards,

Didier