We observe ordinary matter undergo a phase change from say, solid to liquid or liquid to gas when it is cooled or heated past critical values. What happens when subatomic matter is heated or cooled, does it too undergo drastic changes in its properties? Theory predicts that it does. Experiments are currently testing the ideas. In fact there is mounting evidence that when normal nuclear matter is heated to roughly a trillion Kelvin it undergoes sudden changes in its overall properties. It becomes liquid-like (previously thought to be plasma-like), with the relevant particles being quarks and gluons behaving drastically differently from normal matter. Instead of being locked inside the protons and neutrons, quarks and gluons are free to move, limited only by the relatively cool boundaries of the system. Recent discoveries indicate that it is liquid-like, but that it is extremely strongly interacting. It is therefore unlike any matter we have previously encountered. The cleanest experimental tools for studying such matter are the bursts of electromagnetic energy emitted during the production and persistence phases.Practitioners are currently preparing in the laboratory very small samples heated to this extreme. They accomplish this by configuring collisions of subatomic particles thereby converting kinetic energy into heat. By studying the particles that are produced from the hot zone inferences can be made about the details of the reactions. The activity represents safe usage of nuclear physics knowledge to benefit society through pioneering efforts to test and further develop the theory of the strong nuclear force. The intellectual merit of the proposal might be identified as documenting the scientific process as experiments reach past the boundary between ordinary matter and quark matter, and as theory provides guidance. The intrinsic value of the proposed computational projects comes from the guidance they provide to the technically challenging experimental endeavors.
This research proposal concerns models for computing the bursts of energy emitted electromagnetically from highly excited nuclear matter generated in relativistic heavy ion reactions, and also encompasses a research training effort through mentoring students for graduate school, science education, and industry. Technically, quantum field theory will be used to predict and interpret observables for high energy nuclear reactions. Research results will impact the heavy ion community by helping to ensure steady advancement in documented knowledge using electromagnetic probes on subatomic systems. In terms of human resources, the activities themselves will provide capstone experiences for beginning research students.