| Paper | Title | Page |
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| TUPLS002 | Dust Macroparticles in HERA and DORIS | 1486 |
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| Charged dust macroparticles are considered as sources of sudden beam lifetime breakdowns detected in many electron storage rings. This phenomenon is still observed in HERA, although the distributed ion pumps, which were previously identified as dust particle sources, have been removed. We report on the observations of trapped dust during the last period of electron operation and present a detailed model of dust macroparticle dynamics in the HERA e-ring and in DORIS with particular emphasis on stability and possible trapping processes. | ||
| TUPLS003 | A Perfect Electrode to Suppress Secondary Electrons inside the Magnets | 1489 |
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| Electron cloud due to multipacting in the positron ring of B-factories is one of the limitations on the machine performance. Electron cloud in the drift region can be suppressed by solenoid. However, solenoid doesn't work inside a magnet. Numerical studies show that there is strong multipacting in the dipole magnet of the B-factory positron ring. Electrons also can be trapped inside quadrupole and sextupole magnets. The electron cloud from the dipole magnet and wiggler in the positron damping ring of the ILC is a critical limitation on the choice of damping ring circumference, which directly results in a choice of two 6km rings as the baseline for the positron damping ring. Various electrodes have been studied using the program CLOUDLAND. Our studies show that a wire type of electrode with a few hundred voltages works perfectly to kill the secondary electrons inside various magnets. | ||
| TUPLS004 | How Einsteinian Tide Force Affects Beam in a Storage Ring | 1492 |
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| In this paper, we will introduce Einsteinian tide force into a storage ring, and discuss the beam characteristic in a storage ring, we can see that it is quite different from Newtonian tide force act on beam in a storage ring which we know very well. We also discuss the method to measure the beam instability in storage ring caused by these two different tide forces. | ||
| TUPLS005 | Preliminary Study of Using "Pipetron"-type Magnets for a Pre-accelerator for the LHC Collider | 1493 |
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| One of the luminosity limitations of the LHC is the rather low injection energy (0.45 TeV) with respect to the collision energy (7 TeV). The magnetic multipoles in the main dipoles at low field and their dynamic behaviour are considered to limit the achievable bunch intensity and emittance. We report on a preliminary study to increase the injection energy to 1.5 TeV using a two beam pre-accelerator (LHCI) in the LHC tunnel. The LHCI is based on "Pipetron" magnets as originally proposed for the VLHC. The aim of the study is to assess the feasibility and to identify the critical processes or systems that need to be investigated and developed to render such a machine possible. | ||
| TUPLS006 | Optics of a 1.5 TeV Injector for the LHC | 1496 |
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| A concept is being developed to install a second ring above the LHC to accelerate protons from 450 GeV to 1.5 TeV prior to injection into the LHC. The arc and dispersion suppressor optics of the LHC would be replicated in the injector using combined function 'transmission line' magnets orginally proposed for the VLHC. To avoid costly civil construction, in the straight sections housing detectors at least, the injector and LHC must share beampipes and some magnets through the detector portion of the straights. Creating the appropriate optics for these injector-LHC transition regions is very challenging: In addition to matching to the nominal LHC lattice functions at these locations, the changes in altitude of 1.1 m between the injector and LHC must be accomplished achromatically to avoid emittance blowup when the beams are transferred to the LHC. | ||
| TUPLS008 | A new HOM Water Cooled Absorber for the PEP-II B-factory Low Energy Ring | 1499 |
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| At high currents and small bunch lengths beam line components in the PEP-II B-factory experience RF induced heating from higher order RF modes (HOMs) produced by scattered intense beam fields. A design for a passive HOM water cooled absorber for the PEP-II low energy ring is presented. This device is to be situated near HOM producing beamline components such as collimators and provide HOM damping for dipole and quadrupole modes while minimizing impedance to the beam. We present a method of optimizing the impedance characteristics of such devices through the evaluation of loss factors and absorber effectiveness for specific modes using scattering parameter and wakefield analysis. | ||
| TUPLS054 | The Isochronous Mode of the Collector Ring | 1618 |
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The isochronous mode of a storage ring is a special ion-optical setting in which the revolution time of circulating ions of one species does not depend on their velocity spread. In this mode the ring can be used for mass measurement of exotic nuclei. The Collector Ring (CR) [1] of the FAIR project [2] will operate in such mode as time-of-flight spectrometer for short-lived exotic nuclei (T1/2 > 20 μs) produced and selected in flight with the Super-FRS fragment separator [3]. This technique has been developed at the ESR [4]. The dependence of the revolution time in the isochronous ring from its transverse acceptance, the closed orbit distortion, and nonlinear imperfection of the magnet field was investigated analytically and with a Monte-Carlo simulation. The corresponding results will be presented.
References: [1] A. Dolinskii et. al., GSI Annual Report, 2004 [2] W. Henning, Nucl. Phys. A721 (2003)211c [3] H. Geissel, et. al., Nucl. Instr. Meth. B204 (2003)71 [4] M. Hausmann et. al., Nucl. Instr. Meth. A 446 (2000)569 |