eeFACT2016 - Table of Session: MOT4H (Polarization)

Paper	Title	Page
MOT4H1	Introduction – Beam Energy Calibration and Polarization
	A.P. Blondel DPNC, Genève, Switzerland
	Introduction to the session on beam polarization and energy calibration – physics goals: precision measurements of Z (100 keV) and W masses (300 keV) – expected challenges – baseline method uses resonant depolarization for the Z and W masses – physics processes such as e⁺e⁻ –> Z gamma fo the higher energy are adequate for the Higgs and top qoark masses – this requires 1) transverse polarization up to and including the W pair threshold. 2) regular depolarization using spectator bunches. 3) extrapolation from beam energy to center-of-mass energy – if the ring is too small, beam polarization may not be available at the W pair threshold and another method has to be investigated to provide adequate precision.
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOT4H2	Polarization Studies at CEPC
	Z. Duan IHEP, Beijing, People's Republic of China
	Energy calibration with polarized electron/positron beams is an important topic for CEPC at a beam energy of 45 GeV and even 80 GeV. In this paper, the implications of pretzel scheme and partial double ring scheme and possible operation mode for energy calibration is first discussed. Then a preliminary simulation study is reported to investigate if useful beam polarization for energy calibration is achievable at 80 GeV at CEPC.
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOT4H5	Resonant Depolarization and Energy Calibration Issues in FCC-ee
	I. Koop, A.V. Otboev, Y.M. Shatunov BINP SB RAS, Novosibirsk, Russia
	Polarized electron and positron beams are needed for precise energy calibration in storage rings of FCC-ee collider. The resonant depolarization technique and, alternatively, the free spin precession approach shall provide the extremely accurate energy determination of beams in future FCC-ee collider. The relationship between the spin tune and the local beam energy in the collision point will be discussed in the report. Also some preliminary ideas of the magnetic spectrometers for the local beam energy measurement will be presented.
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOT4H6	Simulations of Polarization Levels and Spin Tune Biases in High Energy Leptons Storage Rings	43
	E. Gianfelice-Wendt Fermilab, Batavia, Illinois, USA
	Funding: Work supported by Fermi Research Alliance LLC. Under DE-AC02-07CH11359 with the U.S. DOE Simulations of polarization levels and spin tune biases in high energy leptons storage rings The use of resonant depolarization has been suggested for precise beam energy measurements in the 100 km long Future Circular Collider e⁺e⁻. The principle behind resonant depolarization is that a vertically polarized beam excited through an oscillating horizontal magnetic field gets depolarized when the excitation frequency is in a given relationship with the beam energy. In this paper the possibility of self-polarized leptons at 45 and 80 GeV is investigated. Preliminary results of simulations in presence of quadrupole misalignments and beam position monitors (BPMs) errors for a simplified ring are presented. Even in presence of errors a level of polarization useful for energy calibration seems not out of reach. However it is crucial to demonstrate that a energy measurement precision better than 100 KeV can be actually obtained. The last ring layout with 1 mm vertical beta at the IPs has been also considered. The large vertical beta in the IR quadrupoles makes the closed orbit very sensitive to their vertical misalignment and the orbit correction procedure challenging.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-eeFACT2016-MOT4H6
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOT4H7	Ideas for Siberian Snakes and Spin Rotators in Very High Energy e⁺e⁻ Rings	47
	S.R. Mane Convergent Computing, Shoreham, New York, USA
	The high value of the radiated power in synchrotron radiation in very high energy e⁺e⁻ storage rings presents unique challenges for the design of Siberian Snakes and spin rotators in such machines. This paper presents some ideas which may lead to a feasible design of such devices. The idea is to employ solenoids interleaved with the arc dipoles, to yield a set of noncommuting spin rotations, which can rotate an initially vertical spin to any desired direction. The solenoids should be (approximately) optically transparent, and can be 'spin matched' to the ring using known procedures. Preliminary numerical studies indicate the design may be feasible.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-eeFACT2016-MOT4H7
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

Paper

Title

Page

MOT4H1

Introduction – Beam Energy Calibration and Polarization

A.P. Blondel
DPNC, Genève, Switzerland

Introduction to the session on beam polarization and energy calibration – physics goals: precision measurements of Z (100 keV) and W masses (300 keV) – expected challenges – baseline method uses resonant depolarization for the Z and W masses – physics processes such as e⁺e⁻ –> Z gamma fo the higher energy are adequate for the Higgs and top qoark masses – this requires 1) transverse polarization up to and including the W pair threshold. 2) regular depolarization using spectator bunches. 3) extrapolation from beam energy to center-of-mass energy – if the ring is too small, beam polarization may not be available at the W pair threshold and another method has to be investigated to provide adequate precision.

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOT4H2

Polarization Studies at CEPC

Z. Duan
IHEP, Beijing, People's Republic of China

Energy calibration with polarized electron/positron beams is an important topic for CEPC at a beam energy of 45 GeV and even 80 GeV. In this paper, the implications of pretzel scheme and partial double ring scheme and possible operation mode for energy calibration is first discussed. Then a preliminary simulation study is reported to investigate if useful beam polarization for energy calibration is achievable at 80 GeV at CEPC.

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOT4H5

Resonant Depolarization and Energy Calibration Issues in FCC-ee

I. Koop, A.V. Otboev, Y.M. Shatunov
BINP SB RAS, Novosibirsk, Russia

Polarized electron and positron beams are needed for precise energy calibration in storage rings of FCC-ee collider. The resonant depolarization technique and, alternatively, the free spin precession approach shall provide the extremely accurate energy determination of beams in future FCC-ee collider. The relationship between the spin tune and the local beam energy in the collision point will be discussed in the report. Also some preliminary ideas of the magnetic spectrometers for the local beam energy measurement will be presented.

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOT4H6

Simulations of Polarization Levels and Spin Tune Biases in High Energy Leptons Storage Rings

43

E. Gianfelice-Wendt
Fermilab, Batavia, Illinois, USA

Funding: Work supported by Fermi Research Alliance LLC. Under DE-AC02-07CH11359 with the U.S. DOE
Simulations of polarization levels and spin tune biases in high energy leptons storage rings The use of resonant depolarization has been suggested for precise beam energy measurements in the 100 km long Future Circular Collider e⁺e⁻. The principle behind resonant depolarization is that a vertically polarized beam excited through an oscillating horizontal magnetic field gets depolarized when the excitation frequency is in a given relationship with the beam energy. In this paper the possibility of self-polarized leptons at 45 and 80 GeV is investigated. Preliminary results of simulations in presence of quadrupole misalignments and beam position monitors (BPMs) errors for a simplified ring are presented. Even in presence of errors a level of polarization useful for energy calibration seems not out of reach. However it is crucial to demonstrate that a energy measurement precision better than 100 KeV can be actually obtained. The last ring layout with 1 mm vertical beta at the IPs has been also considered. The large vertical beta in the IR quadrupoles makes the closed orbit very sensitive to their vertical misalignment and the orbit correction procedure challenging.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-eeFACT2016-MOT4H6

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOT4H7

Ideas for Siberian Snakes and Spin Rotators in Very High Energy e⁺e⁻ Rings

47

S.R. Mane
Convergent Computing, Shoreham, New York, USA

The high value of the radiated power in synchrotron radiation in very high energy e⁺e⁻ storage rings presents unique challenges for the design of Siberian Snakes and spin rotators in such machines. This paper presents some ideas which may lead to a feasible design of such devices. The idea is to employ solenoids interleaved with the arc dipoles, to yield a set of noncommuting spin rotations, which can rotate an initially vertical spin to any desired direction. The solenoids should be (approximately) optically transparent, and can be 'spin matched' to the ring using known procedures. Preliminary numerical studies indicate the design may be feasible.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-eeFACT2016-MOT4H7

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)