The relativistic heavy ion collider project: A status report

The relativistic heavy ion collider (RHIC) is a proposed facility at Brookhaven National Laboratory for very high energy collisions of nuclear beams. The project has had a substantial amount of R and D effort and is ready to begin construction within the next year of two, as funding permits. We describe the parameters of the machine, discuss the current status of development work on the project, and describe the requirements for experiments at such a facility.     

Evidence for strong clustering effects in high-multiplicity final states at 30 GeV

A statistical analysis of the event-to-event fluctuations of the langitudinal-momentum distributions is applied to 2-, 3-, 4- and 6-pion production data in $\text{28}\text{GeV}\text{c}$ proton-nucleon collisions, as well as to several models. The results indicate that a dominant feature of these final states is the formation of high-multiplicity clusters of particles.     

Transverse energy distributions in Si-nucleus collisions at 10 GeV/nucleon

Transverse energy distributions have been measured for collisions of 10 GeV/nucleon Si with targets of Al, Cu and Pb using a combination of a NaI wall and a uranium based sampling calorimeter. The measured cross sectionsdσ/dE _T anddE _T /dη are consistent with full stopping and an increase, with increasing values ofE _T , of energy flow into large angles.     

Cloud seeding experiments

Zusammenfassung Der Umstand, dass es selbst nach mehr als 10 Jahren nicht gelungen ist, die Wirkung einer Wolkenimpfung auf Regen- und Hagelfall sicher nachzuweisen, sowie Zweifel an der Bedeutung von Eisbildungskernen für diese Phänomene lassen weitere konventionelle Impfversuche nicht als gerechtfertigt erscheinen, bis die Theorie der Niederschlagsprozesses verbessert ist.     

Synergy in spreading processes: from exploitative to explorative foraging strategies

An epidemiological model which incorporates synergistic effects that allow the infectivity and/or susceptibility of hosts to be dependent on the number of infected neighbors is proposed. Constructive synergy induces an exploitative behavior which results in a rapid invasion that infects a large number of hosts. Interfering synergy leads to a slower and sparser explorative foraging strategy that traverses larger distances by infecting fewer hosts. The model can be mapped to a dynamical bond percolation with spatial correlations that affect the mechanism of spread but do not influence the critical behavior of epidemics.     

Clustering patterns in high-energy hadron collisions

The event-to-event fluctuations of the rapidity distributions are analyzed for semi-inclusive data obtained from 205 GeV/c and 303 GeV/c proton-proton collisions observed at NAL. The results indicate the presence of clustering effects, with cluster sizes approximating those observed in the quasi-elastic events. The average cluster size appears to be independent of the multiplicity of the final state.