120000713
Separating jets from bulk matter in heavy ion collisions at the LHC
We discuss a theoretical scheme that accounts for bulk matter, jets, and the interaction between the two. The physical picture of our approach is the following: Initial hard scatterings result in mainly longitudinal flux tubes, with transversely moving pieces carrying the pt of the partons from hard scatterings. These flux tubes constitute eventually both bulk matter (which thermalizes, flows, and finally hadronizes) and jets, according to some criteria based on partonic energy loss. High energy flux tube segments will leave the fluid, providing jet hadrons via the usual Schwinger mechanism of flux-tube breaking caused by quark-antiquark production. But the jets may also be produced at the freeze-out surface. Here we assume that the quark-antiquark needed for the flux tube breaking is provided by the fluid, with properties (momentum, flavor) determined by the fluid rather than the Schwinger mechanism. Considering transverse fluid velocities up to 0.7c, and thermal parton momentum distributions, one may get a push of a couple of GeV to be added to the transverse momentum of the string segment. This will be a crucial effect for intermediate pt jet hadrons.
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.
121513523
Strange particle enhancement in heavy ion collisions
Abstract In the Regge-Gribov-Veneziano approach to hadron-hadron interactions (implemented strictly in VENUS recently) a proper treatment of double-colour exchange leads to double strings. Such strings correspond to a (say) forward moving quark being linked via two ordinary strings to two backward moving quarks. Leading baryons now require the breaking of two strings. Having twice the chance of producing a strange q− q pair these strings produce twice as many strange baryons as compared to ordinary strings therefore leading to an enhancement of strange baryons in AA relative to pp collisions. We reproduce experimental Λ and also K s and Λ spectra in 200 GeV S+S scattering (using VENUS 4.02).
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.