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ATF2 emittance measurement
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Europe/Zurich
6/R-012 - conference room (CERN)
Present: Robert, Davide Gamba, Marcin Patecki, Angeles Faus-Golfe, Rogelio Tomas, Stefano (from Japan), Michele,
Roberto Corsini.
Limitations of mOTR:
-Intensity: possible wakefields.
-Device: Is it possible that the current device overestimates the beam size? Could this be due to not using special polarization? Angeles says that this effect might be negligible with the current beam size, well few OTRs sometimes suffer from low beam size (5mum).
-Polarizer is not used now. Tests were done in the past not very successfuly.
-Device: Another issue could be that the device has degrees of freedom not controlled by the hardware.
-Device: Mirrors (optical system) should be recalibrated and re-aligned. Some spurious reflections have been observed
occasionaly.
-Software limitation with the fitting. Decision of cutting point for the tails. Tails could be an optical effect.
-Non-suitability of one of the OTR. Possibility to remove of this OTR in the fitting is not automatic.
-Algorithm:
-Is there Synchrotron radiation contributions?
What can CERN BI do?
-Simulations. Effect of polarizer and alignment. The technical drawing can be provided by Angeles. Standard alignment procedure is also requested, but maybe there is no standard alignment procedure... Angeles asks Glen White. Angeles might have the optical drawings at home. Cesar Blanc is here at CERN, he did the mechanical design->meeting. There is information in Javier Alabau's. Matlab scripts are also required (there is paper). Jorge Giner too.
-Checking the alignment of the device can also be done->Stefano July, (need alignment procedure? Glen, Cesar?)
-Comparisons between mOTR and new CERN OTR.
-The correction for small beam sizes could be also be implemented, point spread function. Polarizer on/off, needs preparation.
-4 Shifts in october with beam.
What can CERN ABP do?
Davide and Fabien discussed about measurement using the shintake monitor or IP wire scanner and quad scan. To avoid going below certain beam size (device limitations) you can use more quadrupoles. The parabolic fit is not used anymore, matrix inversion assuming the ideal transfer function. The currents of the quads have to be chosen beforehand to fultill the device limitations or iteration process. Dispersion should be well monitored. Davide could help Fabien.
Further improvements could be: adding a OTR near the IP. Unclear if there is space, which device, etc.
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