55116338
Experiments on the Pulsed Afterglow Operation of an ECR Ion Source
Various experiments have been performed on the 14.5 GHz ECR4 in order to improve the beam yield. The source operates in pulsed “afterglow” mode, and provides currents >120 e A of Pb 27+ to the Heavy Ion Facility on an operational basis. In the search for higher beam intensities, the effects of a pulsed biased disk on axis at the injection side were investigated with different pulse timing and voltage settings. Different plasma electrode geometries were also tested, including running the source without a plasma electrode. The use of CF 4 as mixing gas was investigated, and high secondary electron emission materials, such as LaB 6 and Al2O3, were inserted inside the plasma chamber in an attempt to increase the cold electron density. No proof for higher intensities was seen for any of the tested modifications. On the contrary, several of the modifications resulted in lower source performance, and less stability. Although the source has previously proved to have very stable modes of operation, during the last physics run, after the above tests, the stability decreased and the source settings were very different from the normal operation values.
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
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.
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.
115300845
Status and first beam measurements on the CERN RFQ
56393019
Brief Comments on Higgs-Boson Discovery Potential of Future Tevatron Running
The standard electroweak theory gives an excellent account of many pieces of data over a wide range of energies. Global fits, made within the framework of the standard electroweak theory, favor a light Higgs boson, and exhibit some tension with direct searches. The LEP experiments, which focused on the ee → HZ channel, set a lower bound on the standard-model Higgs-boson mass ofMH > 114.4 GeV at 95% CL [1, 2]. The Tevatron experiments CDF and D0 also search for the standardmodel Higgs boson, examining a variety of production channels and decay modes appropriate to different Higgsboson masses. The most recent combined result exclude the range 160 GeV < MH < 170 GeV at 95% CL [3, 4]. See [5] for an overview of past searches [6]. The disjoint exclusion regions from LEP and the Tevatron make it somewhat complicated to specify the remaining mass ranges favored for the standard-model Higgs boson. A useful example is shown in Figure 1 [7]. In the Gfitter analysis, at 2σ-significance (≈ 95% CL), the
123451779
Top quark condensates and the symmetry breaking of the electroweak interactions
15093335
Topcolor assisted technicolor
A condensate, tt, arising from O(TeV) scale “topcolor”, in addition to technicolor (and ETC) may naturally explain the gauge hierarchy, the large top quark mass, and contains a rich system of testable consequences. A triplet of strongly coupled pseudo-Nambu-Goldstone bosons, “top-pions”, near the top mass scale is a generic prediction of the models. A new class of technicolor schemes and associated phenomenology is suggested in this approach.
119530771
Acceleration in the linear non-scaling fixed-field alternating-gradient accelerator EMMA
In a fixed-field alternating-gradient (FFAG) accelerator, eliminating pulsed magnet operation permits rapid acceleration to synchrotron energies, but with a much higher beam-pulse repetition rate. Conceived in the 1950s, FFAGs are enjoying renewed interest, fuelled by the need to rapidly accelerate unstable muons for future high-energy physics colliders. Until now a ‘scaling’ principle has been applied to avoid beam blow-up and loss. Removing this restriction produces a new breed of FFAG, a non-scaling variant, allowing powerful advances in machine characteristics. We report on the first non-scaling FFAG, in which orbits are compacted to within 10 mm in radius over an electron momentum range of 12–18 MeV/c. In this strictly linear-gradient FFAG, unstable beam regions are crossed, but acceleration via a novel serpentine channel is so rapid that no significant beam disruption is observed. This result has significant implications for future particle accelerators, particularly muon and high-intensity proton accelerators.
50399996
Large distance effects in CP violation and the K0-K0 mass matrix
Abstract Large distance contributions to the K0- K 0 mass matrix are often neglected but have important consequences for CP violation. If “penguins” dominate |ΔS| = 1 weak decays then these large distance contributions correspond to “(penguin)2” diagrams and receive potentially large CP-violating phases. We argue that this effect reduces the size of |ϵ′/ϵ| by ≈ 1 2.5 in the KM model. In the extreme penguin limit, ⨍ = 1 and ϵm = 0, we have |ϵ′/ϵ| ≈ 1 50 .