126324552
Magnetic moments of the Deltas in QCD
14665617
Comment on "Chiral symmetry and the intrinsic structure of the nucleon"- by D.B.Leinweber,A.W.Thomas and R.D.Young
Some remarks are presented on a recent paper (Leinweber,Thomas and Young, Phys.Rev.Lett. 86, 5011, 2001). In particular a statement of the above paper on the fact that the ratio between the magnetic moments of proton and neutron should remain constant at -3/2, independent of the change of the quark mass is discussed on the basis of the general parameterization.
122238217
A relation between the charge radii of π+,K+,K0 derived by the general QCD parametrization
We derive, using the general QCD parametrization, the approximate relation r2(π+) − r2(K+) − r2(K0) where the r's are the charge radii. The relation is satisfied but the experimental errors are still sizeable. The derivation is similar to (but even simpler than) that for r2(p) − r2(n) r2(Δ+) (Phys. Lett. B, 448 (1999) 107).
124837005
SEARCH FOR QUARKS WITH THE FERROMAGNETIC LEVITATION ELECTROMETER
120776511
The non-relativistic quark model
The classification scheme and decay properties of hadron states are investigated in the framework of the non relativistic quark model. The main successes and the unsolved difficulties of the model are presented indicating the future work which could be done to understand and exploit the non-relativistic quark ideas.РезюмеИсследованы схема классификации и распадные свойства адронов в рамках статической модели кварков. Изложены главные успехи и нерешенные проблемы модели, указывая задачи, которые должны быть решены для лучшего понимания и использования нерелятивистских идей.
119592224
New Results in the Search of Quarks in Matter by the Magnetic Levitation Electrometer
Abstract The results of many runs performed levitating in succession several spheres without opening the levitation chamber show the existence of an additional (magneto-electric) force acting on the sphere. Ignoring this force in the analysis of the data produces “spurious” fractional charges.
54676169
Measurement of chromatic effects in LEP
The chromaticity produced by the insertions and the lattice of LEP is corrected in the FODO lattice of the arcs which has horizontal and vertical phase advances of 90/spl deg/ and 60/spl deg/ for the LEP optics presently used. This is done with two horizontal and three vertical sextupole families. To check this correction scheme the non-linear chromaticities have been measured by observing the betatron tunes as a function of RF-frequency, i.e. of momentum deviation. The differences between the results and the expected effects of the sextupoles are interpreted in terms of octupole and decapole components in the dipole magnets. To check the distribution around the ring of the chromaticities and their corrections the betatron phase advances have been measured as a function of momentum deviation. This was done by observing an excited betatron oscillation for 1024 turns in all beam position monitors for different RF-frequencies. The results clearly show the negative chromaticity produced in the straight sections and its correction in the arcs. The parasitic sextupole components are found to be spread uniformly in the arcs within the measurement errors. Under this condition one finds that they have a negligible effect on the dynamic aperture.
119009661
Determination of coupled-lattice properties using turn-by-turn data
A formalism for extracting coupled betatron parameters from multiturn, shock excited, beam position monitor data is described. The most important results are nonperturbative in that they do not rely on the underlying ideal lattice model. Except for damping, which is assumed to be exponential and small enough to be removed empirically, the description is symplectic. As well as simplifying the description, this leads to self-consistency checks that are applied to the data. The most important of these is a {open_quotes}magic ratio{close_quotes} of Fourier coefficients that is required to be a lattice invariant, the same at every beam position monitor. All formulas are applied to both real and simulated data. The real data was acquired June, 1992 at LEP as part of decoupling studies, using the LEP beam orbit measurement system. Simulated data, obtained by numerical tracking (TEAPOT) in the same (except for unknown errors) lattice, agrees well with real data when subjected to identical analysis. For both datasets, deviations between extracted and design parameters and deviations from self-consistency can be accounted for by noise and signal processing limitations. This investigation demonstrates that the LEP beam position system yields reliable local coupling measurements. It can be conservatively assumed that systems of similar design at the SSC and LHC will provide the measurements needed for local decoupling.
107525573
The Q-Loop : a Function Driven Feedback System for the Betatron Tunes During the LEP Energy Ramp
In normal operation LEP is ramped from injection energy, typically 22 GeV, to energies of over 90 GeV where physics taking takes place. Effective control of the betatron during the ramp is essential to ensure good transmission of stored current. The LEP Q-loop is a feedback system used to control the tunes during the energy ramp. By following a pre-programmed tune function it provides a means of avoiding dangerous resonances and thus beam loss. The basic components the Q-loop will be described, and operational results presented. Emphasis will be given to the problems encountered and the solutions found.
59433578
Electron-positron collisions at 209 GeV in LEP
The Large Electron-Positron Collider (LEP) at CERN closed down in November 2000. During the year 2000 electron-positron collisions were established at centre-of-mass energies of up to 209 GeV. The energy reach of LEP was thus extended by another 7 GeV compared to the year 1999. At the same time the luminosity production was kept high and the total delivered luminosity for the year was 233 pb/sup -1/. High beam energy and high luminosity extended the discovery reach of LEP. The successful energy increase of LEP is analysed and the operation and performance in the regime of ultra-strong damping is described.
5752960
THE CERN DETECTOR SAFETY SYSTEM FOR THE LHC EXPERIMENTS
The Detector Safety System (DSS), developed at CERN in common for the four LHC experiments under the auspices of the Joint Controls Project (JCOP), will be responsible for assuring the equipment protection for these experiments. Therefore, the DSS requires a high degree of both availability and reliability. It is composed of a Front-end and a Back-end part. The Front-end is based on a redundant Siemens PLC, to which the safetycritical part of the DSS task is delegated. The PLC Frontend is capable of running autonomously and of automatically taking predefined protective actions whenever required. It is supervised and configured by the CERN-chosen PVSS SCADA system via a Siemens OPC server. The supervisory layer provides the operator with a status display and with limited online reconfiguration capabilities. Configuration of the code running in the PLCs is completely data driven via the contents of a “Configuration Database”. Thus, the DSS can easily adapt to the different and constantly evolving requirements of the LHC experiments during their construction, commissioning and exploitation phases. Currently, the DSS is being installed and commissioned for the construction of the CMS and LHCb experiments.