Abstracts Brochure - CERN

THPCH028
THPCH029
THPCH030
29-Jun-06 16:00 - 18:00 THPCH — Poster Session
phenomenon due to inelastic intrabeam scattering [1]. The low emittance gold beams have always been observed
at injection in the Relativistic Heavy Ion Collider (RHIC). There have been previous attempts to attribute the low
emittance to a cooling due to the exchange of energy between ions during the inelastic intrabeam scattering. The
Fano-Lichten theory[2] of electron promotion might be applied during inelastic collisions between helium like gold
ions in the AGS. During collisions if the ion energy is large enough, a quasi-molecule could be formed, and electron
excitation could occur. During de-excitation of electrons, photons are emitted and a loss of total bunch energy could
occur. This would lead to smaller beam size. We propose to inject gold ions with two missing electrons into RHIC at
injection energy and study the beam behavior with bunched and de-bunched beam, varying the RF voltage and the
beam intensity. If the "cooling" is observed additional.
Crystalline Beams at High Energies
J. Wei (BNL) S. Ochi, H. Okamoto (HU/AdSM) A. Sessler (LBNL)
Y. Yuri (JAEA, Takasaki)
394
Previously it was shown that by crystallizing
each of the two counter-circulating beams,
a much larger beam-beam tune shift can be
tolerated during the beam-beam collisions;
thus a higher luminosity can be reached for colliding beams*. On the other hand, crystalline beams can only
be formed at energies below the transition energy of the circular accelerators**. In this paper, we investigate the
formation of crystals in two types of high-transition-energy lattices, one realized by three-cell missing dipole modules
and the other with negative bends. The latter type satisfies the maintenance condition for a crystalline beam***.
*J. Wei and A.M. Sessler, “Colliding crystalline beams”, EPAC98, p. 862. **J. Wei et al. Physical Review Letters, 73
(1994) p. 3089.***J. Wei et al. Physical Review Letters, 80 (1998) p. 2606.
The External Radiation in Laminated Vacuum Chamber
An exact analytical presentation of multipole
M. Ivanyan, E.M. Laziev, A.V. Tsakanian (CANDLE)
expansion of external radiation field of point
charge in a two-layer round pipe is obtained
for ultrarelativistic case. An outer radiated energy density, shielding coefficients and other parameters are obtained.
The numerical examples for the special case of thin layers vacuum chamber are presented.
Impedance of Laminated Vacuum Chamber for Walls AC Conductivity
The two-layer round tube impedance for
M. Ivanyan, A.V. Tsakanian, A. Vardanyan (CANDLE)
frequency dependent (AC) conductivity of
walls materials is studied. The low and high
frequency asymptotes of the impedance are evaluated. The analytical presentations of the impedance for a number
of special cases are discussed. The comparison of the impedance behavior for DC (frequency independent) and AC
conductivities is given.