Minutes of the CLIC Meeting - 28 March 2003
| Emittance measurements and beam optimization
using Laser Wire Scanners
of Daresbury Damping Ring Workshop
| Gregory Penn, Maxim Korostelev
Gregory Penn presented his
work done for the CLIC study:
The scattering cross-section of an electron beam with a laser pulse can
be used as a diagnostic for beam profiles and hence emittance. With realistic
laser parameters, it should be possible to measure emittances for the
CLIC beam (where the scattering is in the Compton regime) with an accuracy
of around 10%. Simulations in GEANT4 will be presented showing that,
if losses are as anticipated, the accuracy of the measurement will be
limited primarily by the low statistics for detected Compton scattering
events. A basic scheme for optimizing the beam emittance using "emittance
bumps" is also considered, where a single moderately accurate emittance
diagnostic can be used with a large number of tuning parameters to slowly
optimize the CLIC beam. Emittances within a few percent of optimum can
be achieved; when ground motion effects are considered, the results are
not as good.
copy of his transparencies (pdf format)
The present design for the Final Focus has a very low phase advance and
is not compatible with the required phase advance for emittance measurements.
Gregg showed that assuming the required phase advance, the emittance bumps
can be optimized with a single emittance measurement station in the dispersion
suppressor. Already a simple 1-dimensional optimization of 10 bumps with
an emittance measurement precision of 10% can reduce an initially large emittance
to less than about 4% above nominal and keep it to this level.
Maxim Korostelev gave a summary of the Daresbury Damping Ring Workshop.
copy of his transparencies (not available yet)
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Tecker - Last updated 28-03-2003