120916653
The relation between QCD and constituent quark models
120916653
The relation between QCD and constituent quark models
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.
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.
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.
124837005
SEARCH FOR QUARKS WITH THE FERROMAGNETIC LEVITATION ELECTROMETER
56158732
Multiturn Measurements at the CERN SPS
The CERN SPS multiturn facility, based on the new beam orbit measurement system MOPOS, enables the User to acquire the position of the beam at each beam position monitor (BPM) over a number of consecutive turns. When the multiturn acquisition is synchronised with a perturbation imposed on the beam (for instance a fast kick), useful information about the optics of the SPS and the dynamic behaviour of the beam can be extracted from the data. A measurement of the amplitude and phase of the betatron oscillation at each BPM can be used to compare the theoretical optics functions with the real ones, and possibly to detect localised errors. Differences between two such measurements can be used to study the dependence on a variable parameter (e.g. beam intensity, beam energy, etc.) and therefore indirectly measure quantities, like the impedance, distributed along the ring. Finally, due to the 90 degrees phase advance lattice, plotting the positions measured at two consecutive BPMs against each other gives information about the behaviour of the beam in the transverse phase space. Results of measurements performed at the CERN SPS are presented.
85527168
A METHOD TO MEASURE THE BETA-BEATING IN A 90 DEGREES PHASE ADVANCE LATTICE
A method to compute the beta-beating in an accelerator, using as input the measurement of the phase advance of a betatron oscillation between three BPMs (beam position monitors), had been developed in the past[1]. The beauty of this method is that the result does not depend on the the BPM relative errors on the measurement of the oscillation amplitude. Unfortunately this method is not applicable when the phase advance between two of the three BPMs is (close to) 180 degrees. In this latter case the measurement of the amplitude of the beam oscillation should be combined with the phase advance measurement to get a complete picture of the beta-beating. Detecting and filtering BPMs with large gain errors requires some care. A method dealing with these aspects has been developed. Examples obtained by applying the method to real data from LEP and SPS are shown.
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.
115464633
Do We Understand the Luminosity Imbalance
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.