Tracking particles created in subatomic smashups takes precision. So before the components that make up detectors at colliders like the Relativistic Heavy Ion Collider (RHIC) get the chance to see a single collision, physicists want to be sure they are up to the task. A group of physicists and students hoping to one day build a new detector at RHIC—a DOE Office of Science User Facility for nuclear physics research at the U.S. Department of Energy’s Brookhaven National Laboratory—recently spent time at DOE’s Fermi National Accelerator Laboratory putting key particle-tracking components to the test.
What is Nuclear Physics?
More than 99% of the mass of visible matter in the universe is nuclear matter. Protons and neutrons are the building blocks of atomic nuclei. Exotic forms of nuclear matter were present in the early universe and continue to exist today in neutron stars. Nuclear fusion processes at the core of our Sun are the source of the vast energy flow that sustains life on Earth. Nuclear fusion in stars and nuclear processes at the end of stellar life have formed the rich spectrum of elements we observe in nature.
Nuclear physics studies the structure of nuclei—their formation, stability, and decay. It aims to understand the fundamental nuclear forces in nature, their symmetries, and the resulting complex interactions between protons and neutrons in nuclei and among quarks inside hadrons, including the proton.
Experimental nuclear physics drives innovation in scientific instrumentation and has far-reaching impact on research in other fields of science and engineering. From medicine—x-ray and magnetic resonance imaging, radiation therapies for cancer treatment—to materials science—x-ray lithography and neutron scattering—to propulsion and energy production—nuclear physicists have changed our world. Today's research in nuclear physics is not only unraveling fundamental questions about matter and energy but also enabling a host of new technologies in materials science, biology, chemistry, medicine, and national security.
What are we doing in Nuclear Physics at Illinois?
The Nuclear Physics Laboratory (NPL) at the U of I. carries out research in three areas: the precision measurement of the electric dipole moment of the neutron, a broad program studying structure and formation of hadrons, and the precise determination of sin θ13 through a νe disappearance experiment.
We have significant state-of-the-art infrastructure to design and build scientific instrumentation in our laboratory. We focus on the development of instruments for novel experimental approaches to solving open questions in nuclear physics. Recent and current examples include the large volume superconducting spectrometer magnet for the G0 experiment at Jefferson Laboratory, the cryogenic 4He target for the neutron EDM experiment at Oakridge National Laboratory and the W-trigger for the PHENIX experiment at Brookhaven National Laboratory.
We participate in several large-scale experiments at accelerator and reactor facilities in the United States and abroad. A careful balance between experiments in different stages—R&D, construction, data taking, data analysis—results in a broad spectrum of research opportunities. Our large group—nearly 30 graduate students, postdocs, and undergraduate student researchers—focuses on discovery in fundamental nuclear physics, modern data analysis techniques, and advanced instrumentation.
Experiments, status, and major goals
- ATLAS Study of the quark gluon plasma (QGP) produced in the collisions of large nuclei using the modification of jets from their vacuum fragmentation configurations as the propagate through the QGP.
- COMPASS (COmmon Muon Proton Apparatus for Structure and Spectroscopy) is a fixed-target experiment at CERN. It has been using the muon or hadron beam of the Super Proton Synchrotron (SPS) to scatter off a target of unpolarized or spin-polarized protons or deuterons. The SPS is also used to inject beams into the Large Hadron Collider (LHC).
- EXO-200 The search for neutrinoless double beta decay, an exotic nuclear process, which can shed light on both the absolute scale of the neutrino mass spectrum and on the underlying mechanism responsible for the tiny masses that we observe in nature.
- nEXO The success of EXO-200 demonstrates that liquid xenon TPC technology is well suited for a large-scale double beta decay experiment. nEXO is a proposed ~ 5-tonne detector. Its design will be optimized to take full advantage of the liquid xenon TPC concept.
- neutron EDM The possible existence of a non-zero electric dipole moment of the neutron is of great fundamental interest and directly impacts our understanding of the nature of electro-weak and strong interactions. The experimental search for this moment has the potential to reveal new sources of T and CP violation and to challenge calculations that propose extensions to the Standard Model.
- PHENIX An understanding of proton sub-structure is closely connected to the physics of the quantum chromodynamics (QCD) vacuum at high energy densities. In PHENIX, we study the sub-structure of protons in proton-nucleus and polarized proton-proton collisions leading to a very broad and rigorous program in the physics of hadrons and QCD as the theory describing their interactions and structure.
- SeaQuest The Fermilab E-906/SeaQuest experiment is part of a series of fixed target Drell-Yan experiments designed to measure the antiquark structure of the nucleon and the modifications to that structure when the nucleon is embedded in a nucleus. Its principal goal is to extend the landmark measurement of the sea flavor asymmetry d(x)i u(x) in the proton made by its predecessor, E866, to the high-x regime.
- sPHENIX The physics motivations for the sPHENIX detector are to study the quark gluon plasma (QGP) produced in the collisions of large nuclei using the modification of jets from their vacuum fragmentation configurations as the propagate through the QGP. Together with the ATLAS program, the detectors at RHIC (sPHENIX) and the LHC (ATLAS) will allow us to constrain the temperature dependence of the properties of the QGP.