Emittance increase caused by core depletion in collisions

A new effect is presented, which changes the emittance during colliding-beam operation in circular colliders. If the initial transverse distribution is Gaussian, the collision probability is much higher for particles in the core of the beam than in the tails. When small-amplitude particles are removed, the remaining ones therefore have a larger transverse emittance. This effect, called core depletion, may cause a decrease in luminosity. An approximate analytic model is developed to study the effect and benchmarked against a multiparticle tracking simulation. Finally, the time evolution of the intensity and emittances of a Pb bunch in the Large Hadron Collider (LHC) at CERN is calculated, taking into account also other processes than collisions. The results show that integrated luminosity drops by 3--4% if core depletion is taken into account. It is also found that core depletion causes the transverse emittance to be larger when more experiments are active. This observation could be checked against experimental data once the LHC is operational.Comment: 20 pages, 5 figure

Electronic libraries and electronic librarians: Who does what in a national electronic community

This talk will have two parts: First, I'm going to describe very briefly what this new kind of library technology is like through a discussion of the Worm Community System (WCS), why it is going to be very important, and why it will involve a lot of money. What I want to emphasize at the start is that while WCS may seem like an esoteric research project, in fact it is one of the flagship information projects funded by the National Science Foundation. In addition, the National Information Infrastructure Act looms in the immediate future, authorizing an enormous amount of money to be spent in the development of digital libraries in specialized areas. Digital libraries will require information systems like WCS. This project has become a national model of this new kind of information system, but its primary content is really just a special collection, in the same sense you already know. It is an important national effort, but there will be lots of other efforts like this in many different subject areas. Second, I'm going to discuss in more detail what kinds of people are required to do this kind of activity. The roles range from traditional librarians all the way to systems architects. Similarly, the roles range from those that involve no computer knowledge at all to those that involve very intensive computing. My expectation is that people who call themselves "librarians" in the foreseeable future will actually span this entire range, even though now they are significantly skewed towards the traditional end.published or submitted for publicatio

\u3cem\u3eLegacy of Courage: Calgary’s Own 137th Battalion\u3c/em\u3e by Fred Bagley and Dr. H.D. Duncan [Review]

Review of Fred Bagley & Dr. Harvey Daniel Duncan, A Legacy of Courage: Calgary\u27s Own 137th Overseas Battalion, CEF. Calgary: Pulp Street Books, 1994

TEN COMMANDMENTS FOR AGRICULTURAL ECONOMICS (AND PERHAPS OTHER) ADMINISTRATORS

There is some justification for the impression that agricultural economics has entered an era of relatively greater budget stress than that of the recent past. However, optimal strategies for sustaining or enhancing departmental productivity in research, teaching and extension are invariant to the budget level. These "strategies" are discussed in the form of "ten commandments" to department heads.Teaching/Communication/Extension/Profession,

IRRIGATED AGRICULTURE AND THE GREAT PLAINS: PROBLEMS AND POLICY ALTERNATIVES

Resource /Energy Economics and Policy,