Abstracts Brochure - CERN

MOPCH101
MOPCH102
MOPCH103
26-Jun-06 16:00 - 18:00 MOPCH — Poster Session
On the Feasibility of a Spin Decoherence Measurement
In this paper, we study the feasibility of mak-
W.W. MacKay, G. Bunce, H. Huang, A.U. Luccio, T. Roser (BNL) ing a turn-by-turn spin measurement to extract
the spin tune of a synchrotron from a
polarized beam injected perpendicular to the stable spin direction. For the ideal case of a zero-emittance beam with
no spin-tune spread, there would be no spin decoherence and a measurement of the spin tune could easily be made
by collecting turn-indexed polarization data of several million turns. However, in a real beam there is a momentum
spread which provides a tune spread. With a coasting beam the tune spread will cause decoherence of the spins
resulting in a fast depolarization of the beam in a thousand turns. With synchrotron oscillations the decoherence
time can be greatly increased, so that a measurement becomes feasible with summation of the turn-by-turn data from
a reasonable number of bunches (100 or fewer). Both the cases of a single Siberian snake and a pair of Siberian snakes
are considered.
A Straight Section Design in RHIC to Allow Heavy Ion Electron Cooling
The Relativistic Heavy Ion Collider (RHIC)
D. Trbojevic, J. Kewisch, W.W. MacKay, T. Roser, S. Tepikian (BNL) has been continuously producing exciting results.
One of the major luminosity limitations
of the present collider is the intra beam scattering. A path towards the higher luminosities requires cooling of
the heavy ion beams. Two projects in parallel electron and stochastic cooling are progressing very well. To allow
interaction between electrons and the RHIC beams it is necessary to redesign one of the existing interaction regions
in RHIC to allow for the longer straight section with fixed and large values of the betatron functions. We present a
new design of the interaction region for the electron cooling in RHIC.
SPIRAL2 RFQ Prototype – First Results
R. Ferdinand, R. Beunard, V. DESMEZIERES, P. Robillard (GANIL)
A.C. Caruso (INFN/LNS) O. Delferriere, M. Desmons, A. France, D.
Leboeuf, O. Piquet (CEA) M. Fruneau, Y. Gómez-Martínez (LPSC)
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The SPIRAL2 RFQ has been designed to accelerate
a 5 mA deuteron beam (Q/A=1/2)
or a 1 mA particle beam with q/A=1/3 up to
0.75 MeV/A at 88MHz. It is a CW machine
which has to show stable operation, provide
the required availability and reduce losses to a minimum in order to minimize the activation constraints. Extensive
modelisation was done to ensure a good vane position under RF. The prototype of this 4-vane RFQ has been built
and tested in INFN-LNS Catania and then in IN2P3-LPSC Grenoble. It allowed us to measure the vacuum quality,
the RF field by X-ray measurements, the cavity displacement and the real vane displacement during the RF injection.
Different techniques were used, including an innovative and effective CCD measurement with a 0.6 µm precision.
This paper outlines the different results.