problem for beam scanning

[Xu_Liu]

Dear experts,

In the following figure 1, RBEN is a scanning magnet which broadens the proton beam in the X direction. In the Elegant code, I scan the ANGLE of the bend and obtain the beam centroid on the downstream screen, while this coordinates are respect to the reference orbit. Actually, I want to measure the beam centroid within the right coordinate system and plot it as shown in Fig.2. Can you give me some guides?

Thank you for your kindly help!

[michael_borland]

Xu_Liu,

There are two ways to approach this

1. Use the FSE (Fractional Strength Error) parameter on the CSBEND element. Set the ANGLE to the maximum angle, then use FSE<0 to scan to lower angles.
2. Use the ANGLE parameter, but recognize that the centroid position is relative to the floor coordinates as given in the output file
   from the &floor_coordinates command.

Of these, the second choice is more accurate, but requires more work.

--Michael

[Xu_Liu]

Thank you, Michael. I will try it.

Best Regards,
Xu