CAREER: Forward Physics at RHIC and LHC

University Of Kansas Center For Research Inc, Lawrence KS

Investigators

Abstract

Nuclear physicists love to look inside protons and neutrons by smashing particles into them. One goal of this is to understand the force that holds them together and gives them most of their weight. Through a quirk of quantum mechanics, relativity and the uncertainty principle what we see (or rather what a particle sees) inside a proton depends upon how fast we approach it. At low speeds the particle typically sees a lot of empty space a few quarks (which carry the proton's electric charge and most of its momentum) and some gluons (which carry the color force that holds quarks together). These gluons don't carry much momentum and so by the uncertainty principle they have a large size. If a particle hits one of the quarks or gluons then lots of particles will be made. For collisions at higher speeds more gluons appear out of the empty space so that the proton gets crowded. This makes it harder for a particle such as an electron to get through the space between the gluons. At extremely high speeds the gluons are so crowded that they fuse together to form a glass like state, the Colored Glass Condensate. Evidence for such a state was first seen in electron-proton collisions in Germany. On Long Island there is a machine called RHIC that collides gold atoms together. The nucleus of a gold atom contains many protons and neutrons close together. In a nucleus it is easier for the gluons to form a glass since gluons from different protons and neutrons can overlap. Michael Murray is a member of the BRAHMS colloboration which has seen evidence for this effect at RHIC. NSF funding will enable Michael to study these effects at a higher energy collidor that is currently being built near Geneva. This work may help us understand the color force in a new way. Michael is also interested in homeland security. He will be developing a course on "dirty bombs" for first responders. Such a bomb could be as primitive as a stick of dynamite surrounded by radioactive materials or a sophisticated device that produces radioactive aerosols that hang in the air for days. In either case proper training of police and firefighters will help them to alleviate the damager and panic caused by such an attack. -- Bradley D. Keister National Science Foundation 4201 Wilson Blvd. Arlington, VA 22230 +1 703 292-7377 (office) +1 703 292-9078 (fax)