Fractional momentum spread sigma_dp

[Repetto]

Hello,
I am simulating a bunched beam with sigma_dp = 0.001, but respect to my data it's not the same.
In fact, I would like to have an asymmetric sigma_dp (an asymmetry on the left side of my gaussian simulation) to have a better agreement with my data.
Is it possible? If yes, how can I modify my elegant file?
Thank you in advance,
Silvia

[michael_borland]

Silvia,

You can use the program sddssampledist to generate an arbitrary momentum distribution outside of elegant, then load the particles via the sdds_beam command.

Let's assume that your beam is gaussian in (x, xp, y, yp, t), but has a different distribution in momentum. The procedure to generate this beam would be

1. Run elegant to make a nominal distribution of particles.
2. Throw out the unwanted p coordinates.
3. Generate new p coordinates by sampling a desired distribution (sddssampledist).
4. Merge with other coordinates.

The attached archive has a concrete example.

--Michael

[michael_borland]

Silvia,

There are also several examples in the the elegant examples file, under customBeamDistributions.

--Michael