Abstracts Brochure - CERN

TUPLS068
TUPLS069
TUPLS070
TUPLS071
27-Jun-06 16:00 - 18:00 TUPLS — Poster Session
LEIR Electron Cooler Status
G. Tranquille, V. Prieto, R. Sautier (CERN) A.V. Bubley, V.V. Parkhomchuk
(BINP SB RAS)
240
The electron cooler for LEIR is the first of
a new generation of coolers being commissioned
for fast phase space cooling of ion
beams in storage rings. It is a state-of-the-
art cooler incorporating all the recent developments in electron cooling technology (adiabatic expansion, electrostatic
bend, variable density electron beam. . .) and is designed to deliver up to 600 mA of electron current for the cooling
and stacking of Pb 54+ ions in the frame of the ions for LHC project. In this paper we present our experience with
the commissioning of the new device as well as the first results of ion beam cooling with a high-intensity variabledensity
electron beam.
Performance of Fermilab’s 4.3 MeV Electron Cooler
A.V. Shemyakin, A.V. Burov, K. Carlson, M. Hu, T.K. Kroc, J.R.
Leibfritz, S. Nagaitsev, L.R. Prost, S.M. Pruss, G.W. Saewert, C.W.
Schmidt, M. Sutherland, V. Tupikov, A. Warner (Fermilab)
A 4.3 MeV DC electron beam is used to cool
longitudinally an antiproton beam in the Fermilab’s
Recycler ring. The cooling rate is
regulated either by variation of the electron
beam current up to 0.5 A or by a vertical sep-
aration of beams in the cooling section. The paper will describe steps that provided a stable operation and present
the status of the cooler.
Control of Chromaticity in Linear-field Nonscaling FFAGs by Sextapoles
Because of their high repetition rate and large
S.R. Koscielniak (TRIUMF)
apertures, FFAGs are proposed for high-current
medical accelerators suitable for cancer
therapy. The linear-field nonscaling FFAG is made from repeating cells containing D and F combined function magnets.
The betatron tune profiles decrease with momentum; this leads to the crossing of resonances. We examine how
sextapole magnets may be used to flatten the tune profile; in particular (i) whether it is better to place them at the D or
F; (ii) what strength is required; and (iii) what is their effect on the closed orbits and path length? The orbit geometry
is derived from a thin-element model and the tunes from power series in the quadrupole strength. Chromaticity
is corrected by coupling focusing strength to dispersion, which is far stronger in the F element. The zeros of the
orbit dispersion become the poles of the "sextapole strength to flatten the tune at some particular momentum". We
demonstrate that a weak F sextapole can produce a substantial horizontal tune flattening, and has little impact on
other optical properties. Contrarily, placing the sextapole at the D element may destroy the dynamic aperture and or
vertical focusing.
Minimum Cost Lattices for Linear-field Nonscaling FFAGs Modelled by Thin Elements
Previously, linear-field FFAG lattices for
S.R. Koscielniak (TRIUMF)
muon acceleration have been optimized under
the condition of minimum path length
variation. For non-relativistic particles, as are employed in the hadron therapy of cancer, that constraint is removed