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FCC-FS EPOL group meeting 47
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Europe/Zurich
Description
The FCC technical and financial feasibility study comprises a work package (EPOL) on precision determination of the centre of mass energy at FCCee. using resonant depolarisation of the beams, in conjunction with precise measurement of the energy spread and other parameters using physics events in the detectors, and other beam diagnostics in particular to control the collision parameters. Specific equipment involves polarimeters for both beams, polarisation wigglers, and depolarising RF kickers. The possible mono-chromatization of the beams in view of a measurement of the e+ e- —> H (125) process will also be studied and special requirements investigated.
Short group meetings are foreseen at 15:00 on Friday.
FCC-FS EPOL group meeting
Zoom Meeting ID
63437787216
Host
Alain Blondel
Alternative host
Jacqueline Keintzel
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J. Keintzel reminds that the optics comparison review will take place from 21 to 23 January and the Physics Workshop will take place from 26 to 30th January in Munich.
J. Salvesen presents on non-local solenoid compensation in xsuite. Results shown for 4 solenoids. Final polarization is about 85 %, and so in agreement with BMAD. M.-A. Jebramcik asks about the horizontal orbit shift in the model (especially positive vs negative sign), for which J. Salvesen answers that this is purely from a reference frame shift.
J. Tamazirt presents on polarization fast tracking. 1.6 nC are assumed, the error per turn is about 20 asymmetry value , and about ~1 per second for longitudinal polarization. R. Kieffer adds that integrating over one second would be needed. A. Martens adds that 1 um vertical shift gives the same error for vertical polarization. J. Wenninger adds that at LEP the angular error was even more important to control.
J. Wenninger suggests that J. Keintzel will distribute his draft presentation for the comparison review.
J. Wenninger presents on LEP benchmarking and energy shifts from orbit shifts. The latter could lead to significant energy changes which must be understood and controlled.
J. Wenninger presents on polarization transmission through the ramp. He finds that mainly the integer resonances are dominating the depolarization through the ramp.
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