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.
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.
118876352
Event-by-event simulation of the three-dimensional hydrodynamic evolution from flux tube initial conditions in ultrarelativistic heavy ion collisions
We present a sophisticated treatment of the hydrodynamic evolution of ultrarelativistic heavy ion collisions, based on the following features: initial conditions obtained from a flux tube approach, compatible with the string model and the color glass condensate picture; an event-by-event procedure, taking into the account the highly irregular space structure of single events, being experimentally visible via so-called ridge structures in two-particle correlations; the use of an efficient code for solving the hydrodynamic equations in 3 + 1 dimensions, including the conservation of baryon number, strangeness, and electric charge; the employment of a realistic equation of state, compatible with lattice gauge results; the use of a complete hadron resonance table, making our calculations compatible with the results from statistical models; and a hadronic cascade procedure after hadronization from the thermal matter at an early time.
9374989
Macroscopic model of geomagnetic-radiation from air showers
We have developed a macroscopic description of coherent electro-magnetic radiation from air showers initiated by ultra-high energy cosmic rays in the presence of the geomagnetic field. This description offers a simple and direct insight in the relation between the properties of the air shower and the time-structure of the radio pulse. As we show, the structure of the pulse is a direct reflection of the important length scales in the shower.
118180629
A new string model (VENUS 2) for hadronic collisions based on color exchange between quarks and antiquarks
We describe the latest version of the string model VENUS, taking also into account antiquarks as participants in the color exchange (string flip) process, the basic mechanism to form strings. An important consequence is a rapidity plateau for protons and lambdas in symmetric heavy ion collision contradicting the assumption of transparency. 10 refs., 7 figs.