14475053
EXPERIENCE WITH THE GTS-LHC ION SOURCE
For the heavy ion programme of the LHC a new ECRIS type heavy ion source had to be designed and built for Linac3 to fullfill the intensity requirements. Experience acquired during the installation and commissioning of the source and during operation for the LEIR ring commissioning will be presented. The performance of the source and its reliability are evaluated. Further requirements for high reliability, low down time, easy maintenance and for future physics needs will be discussed.
121894301
Studies on ECR4 for the CERN ion program
The CERN heavy ion community, and some other high energy physics experiments, are starting to demand other ions, both heavy and light, in addition to the traditional lead ions. Studies of the behavior of the afterglow for different operation modes of the ECR4 at CERN have been continued to try to understand the differences between pulsed afterglow and continuous operation, and their effect on ion yield and beam reproducibility. The progress in adapting the source and ion beam characteristics to meet the new demands will be presented, as will new information on voltage holding problems in the extraction.
121692361
First results of electron cooling experiments at LEAR
The first results are presented of electron cooling experiments in the Low-Energy Antiproton Ring (LEAR) at CERN, performed with a proton beam of about 50 and 21 MeV. The number of stored protons ranged from 107 to 3 × 109. Cooling times of the order 1 s and proton drag rates of up to 0.7 MeV/s were obtained. The capture of cooling electrons by protons producing hydrogen atoms was used to derive an effective electron temperature (0.25 eV). From the angular profile of the neutral hydrogen beam an upper limit of 3π mm.mrad could be deduced for the horizontal equilibrium proton-beam emittance. The lowest equilibrium momentum spread was 2 × 105 (FWHM), as derived from the analysis of the longitudinal Schottky signal. This Schottky signal exhibited an unusual behaviour with beam intensity and under certain conditions showed a doublepeak structure which was associated with collective beam noise. For very cold beams transverse instabilities were observed, which resulted in a rapid spill-off of protons and a stabilization at lower intensities. The threshold of these instabilities was raised by heating the proton or the electron beam. The cooling of a bunched proton beam was investigated. The reduction of the proton momentum spread led to bunch lengths of about 2 m, containing 3 × 108 protons.
119401628
The Electron Cooling Device for LEAR
The experiments1,2,3 in which low energetic protons were cooled by a “cold” electron beam have proved that this method is a very powerful technique to improve low energy beams and to increase their phase space density by several orders of magnitude in short times. The theoretical understanding of the cooling process is well advanced4,5,6. The applications of this technique, which was invented and developed in Novosibirsk, are manifold7. It seems to be clear that its main domain is the cooling of non-relativistic ions. However, also at extremely high energies, cooling of protons and antiprotons with stored electrons (cooled themselves by synchrotron radiation) can be contemplated8,9.
55729922
Experiments on a 14.5 GHz ECR Source
A device for measuring the speed of the wind at medium altitude by the Doppler effect within the visible frequency range comprises a laser which emits pulses of light, a telescope which receives a scattered light and an interferometer used to measure the spectral shift of the scattered light in relation to the emitted pulse of light. The interferometer is a Fabry-Perot interferometer in which a part of one of the two mirrors of the interferometer is covered with an excess thickness of silica to form two separate filters. The spacing of the two mirrors and the excess thickness of silica are determined in such a manner that the pass bands of each one of the two filters thus constructed are centered on the flanks of the spectral distribution of the backscattered light.
102555920
The LHC Lead Ion Injector Chain
123324722
Status of the top‐quark
A brief review of current predictions and bounds on the mass of the t-quark is presented. Most involve new ideas based on Grand Unification.
16412795
Deconstructing 5D QED
We discuss periodic compactification and latticization of a 5D $U(1)$ theory with a Dirac fermion, yielding a $1+3$ effective theory. We address subtleties in the lattice fermionic action, such as fermion doubling and the Wilson term. We compute the Coleman-Weinberg potential for the Wilson line which is finite for N-branes $g~3,$ due to the ${Z}_{N}$ symmetry, which replaces translations in the $5\mathrm{th}$ dimension. This mode becomes a PNGB in the low energy $1+3$ theory. We derive its anomalous coupling to the ``photon'' and its KK modes.
119432345
Electroweak symmetry breaking by extra dimensions
Electroweak symmetry breaking may be naturally induced by the observed quark and gauge fields in extra dimensions without a fundamental Higgs field. The authors show that a composite Higgs doublet can arise as a bound state of (t,b){sub L} and a linear combination of the Kaluza-Klein states of t{sub R}, due to QCD in extra dimensions. The top quark mass depends on the number of active t{sub R} Kaluza-Klein modes, and is consistent with the experimental value.
112091395
Power Distribution in a CMS Tracker for the SLHC
An upgraded tracker for CMS will need a new architecture for powering to keep the power dissipated in the power cables to acceptable levels. Inductor topologies to reduce the stray magnetic field are discussed together with measurements of the magnetic field produced by prototype inductors. A transformer based DC-DC converter has the potential to produce a high stepdown ratio whilst producing a low stray field and retaining high efficiency. The relative merits of buck configuration and transformer based DC-DC converters are discussed.
121635635
Topcolor: top quark condensation in a gauge extension of the standard model
Abstract We describe a color embedding, SU(3) c →SU(3) 1 ×SU(3) 2 , that is designed to break electroweak symmetries through top quark condensation. The minimal scheme of Bardeen, Hill and Lindner can be recovered by taking the scale of embedding large and fine-tunning the ratio of coupling constants. Models of this kind allow computation of the strength of higher dimension operators which are found to be small. Perhaps fine-tunning can ultimately be avoided in this scheme.