121541770
SCALING OF THE NUCLEON E.M. ELASTIC FORM FACTORS: A GENERAL DERIVATION
Abstract The scaling of the elastic e.m. form factors of the nucleon ( p charge form factor and magnetic form factors of p and n ) has been discussed so far mainly in the non relativistic quark model. We ask: Can the scaling be derived in a model independent way from general properties of QCD? Using the QCD general parametrization we show that: (1) The magnetic form factors of p and n are expected to scale in QCD to a few percent; (2) As to the p electric and magnetic form factors, their scaling, in general, is not guaranteed. The most likely explanation of its empirical validity is that only the “valence quarks” determine the expectation values of both the local charge and magnetization density; the effects of “sea” quarks and antiquarks cancel locally, on the average, as far as the p form factors are concerned.
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.
124837005
SEARCH FOR QUARKS WITH THE FERROMAGNETIC LEVITATION ELECTROMETER
120916653
The relation between QCD and constituent quark models
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.
56290660
The Software for the CERN Detector Safety System
The CERN Detector Safety System (DSS) has been developed to monitor the state of the LHC detectors and protect their components against emer gency situations which other less reliable systems could possibly fail to handle, or which were not co vered by any other system. The DSS consists of two main components: a PLC-based Front-End and a supervisor Back-End. The two parts communicate via the OPC mechanism. The Front-End is the core of the DSS, to which all the runtime safety-critical actions are delegated. These are encoded in an "Alarm-Action Matrix", that can be seen as a set of user-defined rules relating the Input Channels (analogue and digital senso rs) to the Output Channels (actuators, typically on/off interlock switches). One of the user requireme nts is the possibility of modifying these rules at any time, without stopping the system. New Input and Output Channels can also be incrementally added to the system without perturbing the prev iously existing part. To fulfil these requirements without detriment to the safety-critical part, the PLC software has been designed in a completely datadriven way. This approach allowed the PLC code to be kept as simple as possible and independent from the user-defined rules. The rules, as well as the parameteri zation for the Input and Output Channels, are stored into PLC "datablocks", whose contents drive the execution of the PLC code. The supervisor Back-End, based on the CERN-chosen PVSS SCADA system, represents both the “Configuration Interface” and the “Operator Display” for the DSS. The User is able to define and parameterize Input and Output Channels and to modify the set of rules defining the Alarm-Action Matrix. These modifications, after passing some c onsistency checks, are accepted by the Back-End, permanently stored in PVSS "datapoints", and finally mirrored into the PLC datablocks via the OPC mechanism. In addition to this, the Back-End is constantly informed, again through OPC, of any changes in the status of the monitored system . The Back-End then displays all the relevant information to the User, both via an alarm screen and via an interactive synoptic system. This paper describes in greater details some of the ideas behind the design and the implementation of this system.
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.
180753764
PRACTICAL DIAGNOSTIC MEASUREMENTS
123005204
REAL-TIME MONITORING OF BEAM-BEAM MODES AT LEP
By slightly exciting one of two colliding bunches in LEP, it is possible to enhance the eigenfrequencies of the resonant system of the two bunches coupled by the space charge force. The LEP Qmeter has been adapted to detect, among these excited frequencies, the so called - and - modes, whose distance is proportional to the luminosity. A real time display of these quantities provides the Operators with an effective way of finely optimizing the luminosity.
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.