55772711
Accelerating and separating mixed beams of ions with similar charge to mass ratio in the CERN PS complex
Sumrarv mixture were found. Four Booster rings were filled with this beam, captured on h = 10, with a harmonic change (10 + 5) during acceleration [Ref. 41. Sixteen (out of twenty) bunches were transferred to the PS at a magnetic rigidity corresponding to 815 HeV protons (i.e. 258.6 MeV/u). The PS accelerated this beam on the usual h = 20 to transition (6 GeV/u) where the two species, virtually undistinguishable until this stage g occupied different radial orbits and cPf!d be sgparated by RF gymnastics. Four batches of S or In autumn 1987, sulphur 32 ions were accelerated by the CERN machines to a world record energy of 6.4 TeV. An Electron Cyclotron ReSOnanCe source produces sulphur ions as a 5 per cent ‘contamination” of an oxygen ion beam. As their charge-to-mass ratios differ by only 5.4 E-4 , the two species are not distinguishable by the downstream accelerators (RFQ, Linac 1, PSB) , though measurable in a specially equipped spectrometer line. In this way, enough current is available for controlled acceleration at low beta in the PSB. However, at phase transition energy in the PS about 6 GeV/nucleon (CeV/u) this synchrotron becomes an extremely fine spectrometer, with sulphur 16t ions being driven inwards, and oxygen 8t outwards. This can be used for separating the beams by manipulating the low-level radio-frequency system at transition, SO that either oxygen or sulphur is selected. Indeed, the SPS could be fed with a fairly intense oxygen beam for setting-up, and later with some 2E7 sulphur ions per PS cycle. The required RF manipulations, the present understanding on beam dynamics at transition, as well as diagnostic techniques for determining the amount of sulphur are presented.
102555920
The LHC Lead Ion Injector Chain
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
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.
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.
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.
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.
126363269
Cross-section for topcolor Z-prime(t) decaying to t anti-t: Version 2.6
14139978
THE DIFFRACTIVE QUANTUM LIMITS OF PARTICLE COLLIDERS
Quantum Mechanics places limits on achievable transverse beam spot sizes of particle accelerators. We estimate this limit for a linear collider to be \Delta x > \hbar c f/E\delta_0 where f is the final focal length, E the beam energy, and \delta_0 the intrinsic transverse Gaussian width of the electron wave-function. \delta_0 is determined in the phase space damping rings, and we find \delta_0 \approx \sqrt{\hbar c /eB} where B is the typical wiggler magnetic field strength in this system. For the NLC \delta_0 = 25 nm, and \Delta x = 0.06 nm, about two orders of magnitude smaller than the design goal. We can recover a crude estimate of the classical result when we include radiative relaxation effects. We also consider a synchrotron and obtain \Delta x > \sqrt{\hbar c f/E} = O(1.0) nm. We discuss formulation of quantum beam optics relevant to these issues.
119192830
Is the Higgs boson associated with Coleman-Weinberg dynamical symmetry breaking?
The Higgs mechanism may be a quantum phenomenon, i.e., a Coleman-Weinberg potential generated by the explicit breaking of scale symmetry in Feynman loops. We review the relationship of scale symmetry, trace anomalies, and emphasize the role of the renormalization group in determining Coleman- Weinberg potentials. We propose a simple phenomenological model with "maximal visibility" at the LHC containing a "dormant" Higgs doublet (no VEV, coupled to standard model gauge interactions $$SU(2)\times U(1)$$) with a mass of $$\sim 380$$ GeV. We discuss the LHC phenomenology and UV challenges of such a model. We also give a schematic model in which new heavy fermions, with masses $$\sim 230$$ GeV, can drive a Coleman-Weinberg potential at two-loops. The role of the "improved stress tensor" is emphasized, and we propose a non-gravitational term, analogous to the $$\theta$$-term in QCD, which generates it from a scalar action.