My recent calculations (11 and 16 May) of the electron and positron
orbits at the sync light source points were done with
the design pretzel settings (2400 at 5 GeV and 3300
at 2 GeV.) However, at 2 GeV, we operate at a pretzel
setting of 2850. It turns out that for this pretzel
the orbits at 2 GeV and 5 GeV are more similar.
I have also calculated the orbit and beta distortions
at the electron sync light source points which arise from
the BBI. I used the operating positron configurations
of 4x5 10 mA/bunch at 5 GeV and 8x3 2 mA/bunch at 2 GeV.
The orbits and beta's vary with current and
are slightly different for each electron bunch, as
can be seen here:
2 Gev:
http://www.lns.cornell.edu/~critten/cesr/injection/notes/17may06/synclight_1307/
5 Gev:
http://www.lns.cornell.edu/~critten/cesr/injection/notes/17may06/synclight_1306/
Modulo the slight bunch-to-bunch differences, the
orbit and beta's for electrons in our present operating
conditions are about:
2 GeV 5 GeV
----- -----
e- e-
-- --
X (cm) 1.2 0.97
Y (cm) 0.01 0.0
XP (mrad) 0.55 0.50
YP (mrad) 0.0 0.01
BetaX (m) 20 12
BetaY (m) 17 12
I have updated the calculations of the source positions
and reflection angles at the primary mirror for these
operating conditions here:
http://www.lns.cornell.edu/~critten/cesr/synclight/16may06/all/
These results show that such effects do not account
for our difficulty in getting compatible mirror alignments
at the two energies.
-- jim
========================================================
James Crittenden Tel. (607) 255-9424
Wilson Synchrotron Laboratory Fax (607) 255-8062
Cornell University
Ithaca, New York 14853-8001
========================================================
James A. Crittenden wrote:
> Having found that the horizontal orbit angles at the source points
> differ in the 2 and 5 GeV optics by 40% (appended, mail of 11 May), I
> checked these
> angles in the SBP optics presently under design (chess_20060123).
> I found these angles have changed by a similar amount, but
> in the other direction. One can conclude that the horizontal
> orbit angles at the light source points are not constrained
> by the design procedure at the 0.2 mrad level.
>
> 5 GeV (optics design in progress)
> ---------------------------------
>
> e+ e-
> -- --
>
> X (cm) 1.13 1.230
> Y (cm) 0.005 -0.0049
>
> XP (mrad) -0.97 1.02
> YP (mrad) 0.013e-3 0.013e-3
>
> BetaX (m) 12.8 10.4
> BetaY (m) 11.0 10.9
>
>
> ===================================================================================
>
>
> I also calculated the effects on the source points and reflection angles
> arising from switching from 2 to 5 GeV, using the pretzel orbits found
> in the calculations from May 11. The difference in source points and
> angles can be seen here:
>
>
http://www.lns.cornell.edu/~critten/cesr/synclight/16may06/all
>
> The source points move by 5 cm and the reflection angles by about 0.2 mrad.
> These difference don't seem large enough to explain why we have lost
> the electron light at 5 GeV.
>
> -- jim
>
> ========================================================
> James Crittenden Tel. (607) 255-9424
> Wilson Synchrotron Laboratory Fax (607) 255-8062
> Cornell University
> Ithaca, New York 14853-8001
> ========================================================
>
> Presenting operating lattices:
>
> 2 GeV 5 GeV
> ----- -----
>
> e+ e- e+ e-
> -- -- -- --
>
> X (cm) 1.15 1.20 0.95 0.95
> Y (cm) -0.01 0.01 0.001 -0.001
>
> XP (mrad) -0.77 0.78 -0.56 0.58
> YP (mrad) 0.7e-3 0.7e-3 2.2e-3 2.2e-3
>
> BetaX (m) 17.5 18.7 14.3 13.8
> BetaY (m) 16.2 15.5 11.1 8.1
>
>
>