1. Update on MEIC Nonlinear Dynamics Work
V.S. Morozov
Teleconference on Nonlinear Dynamics
August 4, 2015
F. Lin

2. Nonlinear Parameter Study Continued
Phase advance between the h and v sextupoles adjusted to exactly /2 in both planes
Phase advance from IP to sextupoles adjusted to exactly (n+1/2) in appropriate planes
W minimized at IP using “non-linear” sextupoles
x,y = 1 using “linear” sextuples
Betatron tunes: x = 25.22, y = 23.16
No significant improvement IP

3. Some Non-Linear Parameters
Chromaticities
dnux/dp = e-01; dnux/dp2 = e+03; dnux/dp3 = e+06
dnuy/dp = e-01; dnuy/dp2 = e+03; dnuy/dp3 = e+06
Chromatic  function dependence
dbetax/dp (m) = e-02; dbetay/dp (m) = e-02
Non-linear dispersion
etax2 (m) = e+00; etax3 (m) = e+02
etay2 (m) = e+00; etay3 (m) = e+00
Tune dependence on amplitudes
dnux/dJx (1/m) = e+02; dnux/dJy (1/m) = e+04; dnuy/dJy (1/m) = e+02
1st-order driving terms
h11001 = e+01; h00111 = e+01; h10100 = e+00;
h10010 = e+00; h21000 (1/m1/2) = e-02; h30000 (1/m1/2) = e-03;
h10110 (1/m1/2) = e+01; h10020 (1/m1/2) = e+01; h10200 (1/m) = e+00;
h20001 = e+00; h00201 = e+01; h10002 (1/m1/2) = e+00;
2nd-order driving terms
h22000 (1/m) = e+02; h11110 (1/m) = e+04; h00220 (1/m) = e+02;
h31000 (1/m) = e+01; h40000 (1/m) = e+02; h20110 (1/m) = e+03;
h11200 (1/m) = e+04; h20020 (1/m) = e+03; h20200 (1/m) = e+03;
h00310 (1/m) = e+02; h00400 (1/m) = e+01

4. What Is the Issue? Second order amplitude dependent tune shift
Consider a single CCB (the downstream one) with N = 3
h/v sextuple cross-talk within a single CCB explains the large x/Jy value: (x/Jy)21 and (x/Jy)23 independent of tune and add up
x/Jy j
Total 1 2 3 k
223.0
-223.0
-20.0

5. Conclusions & Outlook
There seems to be a fundamental problem with the CCB scheme
There appear to be no phase advance combination that would cancel sextupole contributions to x/Jy
Additional sextupole(s) needed, this then starts resembling –I sext pair scheme
x/Jy is the hardest to compensate with octupoles, would require three of them
Important lesson: phase advance between sextupole pairs matters
Further work
Present a side by side comparison to the collaboration and make a down selection
Get non-interleaved –I sextupole pair optics from SLAC for further studies
Continue optimization
Continue error studies
Start thinking about the electron ring