R56 question

[astecfrank]

Hi,

I'm trying to calculate R56 for a lattice containing RF cavities (RFCA) using matrix_output and I'm confused about the results I'm seeing.

The R56 downstream of the cavities seems to change when I change the cavity field (VOLT), or depends on whether I set CHANGE_P0 to 0 or 1.

My naive assumption was that the R56 should not depend on beam energy (I thought R56 just depends on the bend angles which are defined independent of energy).

I've tried to simplify my lattice to test my assumptions, and also look through the source code to understand the R56 calculation, but I'm still stuck. The cavities seem to change the R56 downstream, which is contrary to what I expect.

thanks for any help
Frank

[michael_borland]

Frank,

R56 shouldn't change with post-chicane acceleration. I tried a test (files attached) and confirmed this behavior.

If you have acceleration ahead of the chicance, then R56 *can* change. The reason is that R56 = ds/ddelta, where delta=(p-p0)/p0, p0 being the initial momentum (i.e., prior to acceleration).

--Michael