Messages Parallel Tuesday 27, WP1
Tatiana Pieloni, Yi Wu, Eliana Gianfelice, Ivan Koop
WG1 27th Sep
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Integration of Wiggler and Polarimeter
Michael Hofer
Wigglers: shorten polarization time
Follows three block LEP design, packages of 3 units with L = 12 m
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Integration of Wiggler and Polarimeter
Michael Hofer
Wiggler location → dispersion free region and low beta function
16m long drift space downstream of the interaction point
Ensured physical aperture (Dx=0.8 mm excursions)
Lifetime implications under study
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Integration of Wiggler and Polarimeter
Michael Hofer
Wiggler location → dispersion free region and low beta function
16m long drift space downstream of the interaction point
Ensured physical aperture (Dx=0.8 mm excursions)
Lifetime implications under study
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Integration of Wiggler and Polarimeter
Michael Hofer
Polarimeter uses spin-dependent Compton scattering of circularly polarized laser with e+- beams
Baseline → 1 polarimeter per beam investigated in two options
New proposal → 1 polarimeter per beam per IP upstream of each IP, proposed but not yet investigated.
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Integration of Wiggler and Polarimeter
Michael Hofer
For Baseline: two options considered
Upstream of IP: sufficient space for detectors (300 mm)
Upstream of RF: alternative proposal to increase beam separation of non-IP straight to accommodate detectors between beams (80-100 cm)
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Integration of Wiggler and Polarimeter
Michael Hofer
Two options considered:
Upstream of IP: sufficient space for detectors (300 mm)
Upstream of RF: alternative proposal to increase beam separation of non-IP straight to accommodate detectors between beams (80-100 cm)
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Open questions:
FCCee polarization wigglers
Jeremie Bauche
FCC wigglers: 16m, space is not a problem
A magnet design with floating poles similar to the LEP damping/emittance wigglers has been proposed for the FCC-ee polarization wigglers
Field self-cancellation, dynamic range of the wigglers needs to be confirmed
Effect of trim coil: longitudinal field profile affected
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FCCee polarization wigglers
Jeremie Bauche
FCC wigglers: 16m, space is not a problem
A magnet design with floating poles similar to the LEP damping/emittance wigglers has been proposed for the FCC-ee polarization wigglers
Field self-cancellation, dynamic range of the wigglers needs to be confirmed
Effect of trim coil: longitudinal field profile affected
Need for:
Hard SR → energy deposition studies should be a priority
Pros → Appealing design → for safer beam operation thanks to self cancellation of B field.
Cons → Trimmed coils need detailed specs from optics studies (accuracy, dynamic range, field sensitivity and harmonic contents of long field profile)
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Spin-PTC in max: status and future
Felix Carlier
Requirements for spin simulations for FCC-ee in MADX:
Spin calculations were already present in PTC → Now properly interfaced with Madx
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Spin-PTC in max: status and future
Felix Carlier
Preliminary spin comparisons Bmad-PTC and Madx-PTC
A notable change in spin tune is observed between Madx and Bmad implementations of PTC, but also Bmad does not use the calculated spin tune from PTC
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Spin-PTC in max: status and future
Felix Carlier
Compare closed orbit stable spin direction n0 and spin tune with different quadrupole offsets, at different energies
In BMAD, number of slices, integration order matters
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Spin-PTC in max: status and future
Felix Carlier
Compare closed orbit stable spin direction n0 and spin tune with different quadrupole offsets, at different energies
In BMAD, number of slices, integration order matters
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Preliminary cross checks have shown some differences that are under investigation
Continue the cross-checks between these two tools
An ergodic approach to polarization lifetime
Francois Meot
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An ergodic approach to polarization lifetime
Francois Meot
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An ergodic approach to polarization lifetime
Francois Meot
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The ergodic approach allows for faster and larger parameter space studies.
Such option could be extremely useful for optimization and defining operational scenarios.
Fast First-Order Spin Propagation via the Bmad Library
Jacob Asimow
Bmad: let the user choose on an element-by-element basis
“SPRINT” Spin Tracking: solve differential equation once, reference later
Compare equilibrium polarization on EIC ESR 5.3 lattice: nearly identical results produced ~6x faster via SPRINT!
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Fast First-Order Spin Propagation via the Bmad Library
Jacob Asimow
Bmad: let the user choose on an element-by-element basis
“SPRINT” Spin Tracking: solve differential equation once, reference later
Compare equilibrium polarization on EIC ESR 5.3 lattice: nearly identical results produced ~6x faster via SPRINT!
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Speed in spin calculations is a very important challenge!
Sprint allows for faster 1st order spin maps
Further improvements of BMAD speed can be done in the main code structure not on the maps and tracking part.
Systematics in Energy-Depolarization frequency relationships
Anton Bogomyagkov
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FCC-ee goal is to measure with 10-7 precision – how each systematic in the energy calibration procedure will affect the central mass energy?
Systematics in Energy-Depolarization frequency relationships
Anton Bogomyagkov
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Systematics in Energy-Depolarization frequency relationships
Anton Bogomyagkov
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The FCC-ee goal of 10-7 precision defines tolerances and constraints that look challenging.
Particularly the requirement of a ring vertical alignment of 10-4 over 1 Km
Verification with simulation tools is fundamental to validate and understand these systematics → per machine seed measure the energy, the rms orbit deviation and the derivative to characterize the dependency of the CME and spin tune needs to be developed
A lot of challenges a-head of us!
Thanks again to all the speakers!
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