117614987
STRING MODEL APPROACH TO NUCLEAR SCATTERING
We discuss the string model of hadronic and nuclear scattering at ultrarelativistic energies. The main purpose is to treat theoretical concepts common to essentially all successful models: strings, Pomerons, and their “marriage” in the string model approach.
119099623
A unified treatment of high-energy interactions
It is well known that high-energy interactions as different as electron-positron annihilation, deep inelastic lepton-nucleon scattering, proton-proton interactions, and nucleus-nucleus collisions have many features in common. Based upon this observation, we construct a model for all these interactions, which relies on the fundamental hypothesis that the behaviour of high-energy interactions is universal.
122077200
Generation of complete events containing very high-pT jets
The study of very high transverse-momentum jets will be an important issue at the LHC, in particular since the corresponding cross sections will be considerably larger than at RHIC energies. Jets are expected to provide information on QGP formation, due to the energy loss of fast partons in the medium. Jet cross sections can in principle be compared to simple pQCD calculations, based on the hypothesis of factorization. But often it is useful or even necessary to not only compute the production rate of the very high-pT jets, but in addition the “rest of the event”. The proposed talk is based on recent work, where we try to construct an event generator—fully compatible with pQCD—which allows one to compute complete events, consisting of high-pT jets plus all the other low pT particles produced at the same time. Whereas in “generators of inclusive spectra” like Pythia one may easily trigger on high-pT phenomena, this is not so obvious for “generators of physical events”, where in principle one has to generate a very large number of events in order to finally obtain rare events (like those with a very high-pT jet). We shall discuss how we overcome these difficulties in the framework of the EPOS model.
18342055
Latest Results from the Air Shower Simulation Programs CORSIKA and CONEX
Interpretation of EAS measurements strongly depends on detailed air shower simulations. The uncertainty in the prediction of shower observables for different primary particles and energies is currently dominated by differences between hadronic interaction models. The new models QGSJETII-3 and EPOS 1.6, which reproduce all major results of existing accelerator data (including detailed data of RHIC experiments for EPOS), have been implemented in the air shower simulation programs CORSIKA and CONEX. We show predictions of these new models and compare them with those from older models such as QGSJET01 or SIBYLL. Results for important air shower observables are discussed in detail.
119442033
Cosmic ray air shower characteristics in the framework of the parton-based Gribov-Regge model NEXUS
The purpose of this paper is twofold: first we want to introduce a new type of hadronic interaction model (NEXUS), which has a much more solid theoretical basis than, for example, presently used models such as QGSJET and VENUS, and ensures therefore a much more reliable extrapolation towards high energies. Secondly, we want to promote an extensive air shower (EAS) calculation scheme, based on cascade equations rather than explicit Monte Carlo simulations, which is very accurate in calculations of main EAS characteristics and extremely fast concerning computing time. We employ the NEXUS model to provide the necessary data on particle production in hadron-air collisions and present the average EAS characteristics for energies ${10}^{14}\ensuremath{-}{10}^{17}$ eV. The experimental data of the CASA-BLANCA group are analyzed in the framework of the new model.
14827188
Coherent Cherenkov radiation from cosmic-ray-induced air showers.
Very energetic cosmic rays entering the atmosphere of Earth will create a plasma cloud moving with almost the speed of light. The magnetic field of Earth induces an electric current in this cloud which is responsible for the emission of coherent electromagnetic radiation. We propose to search for a new effect: Because of the index of refraction of air, this radiation is collimated in a Cherenkov cone. To express the difference from usual Cherenkov radiation, i.e., the emission from a fast-moving electric charge, we call this magnetically induced Cherenkov radiation. We indicate its signature and possible experimental verification.
112503547
Survey of vibration amplitudes throughout the linac
The magnitude of vibrations of the Linac structure due to on site disturbances, such as cooling towers, pumps, generators, Highway 280 overpass traffic, is of interest. CN-263, for example, discusses tolerances of random (i.e., uncorrelated) quad jitter and suggests that amplitudes should not exceed 0.7 microns rms. This note describes the results of a series of measurements carried out in the summer of 1983. In general, the tolerance is not exceeded, but there appears not to be a good safety factor at low frequencies.
113927606
Ground motion: frequency of occurrence versus amplitude of disturbing transient events
Successful collider operation requires that ground motion not exceed certain tolerances. In this note it is pointed out that on occasion these tolerances are exceeded. The frequency of such events and their amplitudes, measured as a function of time of day, have been measured. An examination of the data leads one to conclude that most events are of cultural (i.e., man-made) origin. 2 references, 20 figures.
107438884
Ground motion - some relative phase measurements in the PEP tunnel
The spatial as well as the temporal characteristics of ground motion are of interest when one attempts to evaluate orbit distortions resulting from time varying quadrupole displacements. In other words, one needs to know the spatial correlations of quad displacements along the orbits path. A correlation with the betatron wavelength would be, for example, potentially more dangerous than from say purely statistically uncorrelated quad motions. The space versus time relationship of ground motion is, of course, related by the effective velocity of sound in the supporting medium. The medium consists of the ground itself, the tunnel floor and the magnet support structure - the latter two having perhaps transmission line characteristics of their own. The question therefore is: What values of velocity should one use for the various types of disturbances that will be encountered in practice. This note describes the results of a minimal experiment designed to answer two questions:(a) Is it at all possible to measure correlations in an existing tunnel with simple equipment. (b) Are the results consistent with the known geophysical characteristic of the site. The answer to both questions, we believe, is surprisingly, yes.