Abstracts Brochure - CERN

WEPCH078
WEPCH079
WEPCH080
WEPCH081
28-Jun-06 16:00 - 18:00 WEPCH — Poster Session
Measurement of Wake Effects by Means of Tune Shift in the KEKB Low Energy Ring
The electron cloud produced by the positron
T. Ieiri, H. Fukuma, Y. Ohnishi, M. Tobiyama (KEK)
beam induces single-bunch and coupledbunch
wakes, in addition to a tune shift. Effects
of the dipole wake-field including the electron cloud were tried to measure in the KEKB Low Energy Ring. A test
bunch was placed behind a bunch-train of the positron beam, even though a test bunch itself might interact with the
remaining electron cloud. We measured a current-dependent tune-shift of a test bunch under constant train-current,
while changing the bucket position of a test bunch. The tune shift indicated a strong defocusing field, however,
tended to a focusing field when a test bunch approached a train with high train-current. The results are discussed,
considering variations of the electron cloud density.
Effects of Intrinsic Nonlinear Fields in the J-PARC RCS
H. Hotchi, F. Noda (JAEA/J-PARC) S. Machida (CCLRC/RAL/
ASTeC) A.Y. Molodozhentsev (KEK)
294
In order to accelerate a high intense proton
beam with small particle losses, the J-PARC
RCS, which is being constructed at JAEA, has
a large acceptance. In such synchrotrons, the
nonlinear motion of the beam particles, especially moving away from the axis of the elements, is a common issue,
and it becomes essential to consider intrinsic field nonlinearities. The main sources of nonlinear magnetic fields in
the RCS are as follows: fringes of the main dipole and quadrupole magnets, sextupole fields used for the chromatic
correction, leak fields from the injection and extraction beam lines, etc. In this paper, we will discuss influences of
the intrinsic field nonlinearities and a cure for the induced betatron resonances, based on single-particle and multiparticle
tracking simulations.
Beam Simulation of SQQ Injection System in KIRAMS-30 Cyclotron
D.H. An, J.-S. Chai, H.B. Hong, S.S. Hong, M.G. Hur, W.T. Hwang,
H.S. Jang, I.S. Jung, J. Kang, J.H. Kim, Y.S. Kim, M.Y. Lee, T.K. Yang
(KIRAMS)
The injection system of KIRAMS-30 cyclotron
consists of a double gap buncher, an SQQ,
and a spiral inflector. Initial beam with
100 mmmrad has been generated by random
Gaussian function in the transverse plane
and random uniform function in the longitudinal direction. Using the 3D electric and magnetic fields of a buncher,
SQQ, inflector, and return-yoke bore, the characteristics of the beam injected into the KIRAMS-30 cyclotron’s central
region has been obtained. This paper presents the results of its beam characteristics and parameters of each beam
element.
External Injection into Cyclotron by Means of Solenoid
The proton (H-) low (100 mkA) intensity
L.M. Onischenko, E. Samsonov (JINR)
beam injected by means of the solenoid
comes to the first cyclotron orbit without the
beam emittance deterioration. This is demonstrated by computer simulation.