Rutgers University Department of Physics and Astronomy
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Modern nuclear physics seeks to understand the structure of all hadronic matter. Traditional nuclear structure studies explore new regions of excitation, angular momenta, and stability that have only become accessible to detailed study through the advent of more advanced detector arrays and radioactive ion beams. The structure of light nuclei has advanced both through modern computational techniques using the nucleon-nucleon force, and through intermediate energy photon and electron experiments that have illuminated the role played by mesons, baryon resonances, and the quark substructure of the nucleon in the nucleus. The baryons and mesons themselves are studied experimentally over a wide energy range with photon, neutrino, electron, meson, and proton beams, and are studied theoretically with Quantum ChromoDynamics computations, using Chiral Perturbation Theory, Lattice QCD, and perturbative QCD. Fundamental symmetries are probed in a variety of experiments, such as parity violating electron scattering from quarks in the nucleon. Indeed, modern nuclear physics now encompasses areas of research which had been considered the domain of particle physics. Our experimental nuclear physics group studies a range of these topics, with two faculty members in nuclear structure and three in intermediate energy.
The low-energy experimentalists probe nuclear structure at the limits of angular momenta, stability, and elongation, by measuring electromagnetic moments, level energies, and gamma-ray transitions using a variety of nuclear probes. This group has also been noted for their broad range of interests, many of which are only peripherally related to standard nuclear physics, but could more appropriately appear under the atomic physics or condensed-matter heading.
The three intermediate energy physicists, with a long history of work with hadron probes, now concentrate on experiments using photon, neutrino, and electron beams. These experiments will try to determine basic properties of the nucleon and few-body systems, and to investigate how the nuclear environment affects the nucleon. Many of the experiments involve polarized electron beams and measurements of the polarization of recoil protons, a field in which they are world leaders.
Major nuclear structure efforts are located at the Argonne,
Berkeley, and Oak Ridge National Laboratories, and at the Yale University accelerator
laboratory. The intermediate energy group is focused at Jefferson
Laboratory in Newport News, Virginia. The major facility there is
CEBAF, a 6
GeV CW electron accelerator that is now the leading accelerator in the
for intermediate energy nuclear physics.
The group is also involved in
constructing the recently approved MINERνA experiment
at Fermilab, which studies neutrino nucleus scattering.
Professor Jolie Cizewski
I am interested in studying and understanding the structure of heavy atomic nuclei (mass 80), and in particular, nuclei with many more neutrons than stable isotopes. Theoretical models predict that the shell structure that characterizes stable nuclei may be quenched in very neutron-rich nuclei. Some of these neutron-rich nuclei also lie along the path that limits the rapid neutron capture process of nucleosynthesis. The studies of the properties of unstable nuclei are performed at the Holifield Radioactive Ion Beam Facility at Oak Ridge National Laboratory in Tennessee using beams of rare isotopes. The current focus is on determining the single-neutron excitations of neutron-rich N=50 and N=82 nuclei, and probing the shell structure far from stability. I also serve as the Director of the Center of Excellence for Radioactive Ion Beam Studies for Stewardship Science. Earlier work involved studying highly elongated, superdeformed, excitations in heavy nuclei, the properties of nuclei near the proton drip line, and the role of dynamical symmetries and supersymmetries in understanding collective excitations in nuclei.
Professors Ronald Gilman, Charles Glashausser, and Ronald Ransome
Our research program for the past several years has focused on the structure of the nucleon and light nuclei, and on what happens to a nucleon in the nuclear environment. We began the new era of physics at Jefferson Lab by building on our recognized expertise in spin physics to construct the world's largest focal plane polarimeter (FPP), along with our colleagues at William & Mary. The FPP, sited at Jefferson Lab Hall A, was used in almost half of the experiments run in the first several years of operation. It has produced particularly nice results on the electromagnetic structure of the proton in elastic ep scattering, the excitation of the proton to the Δ resonance, the structure of the deuteron in photo-disintegration at high energies, and investigating possible nucleon structure modifications in the nucleus with 4He(e,e'p). We have a rich series of future experiments planned for the period 2006-2008. We should be able to continue the measurements of the electromagnetic structure of the proton in elastic ep scattering to higher momentum transfer and higher resolution, and to investigate the role of two-photon exchange in this process. Our studies of the deuteron structure should be expanded over a wider range, to illuminate the transition from hadronic to quark degrees of freedom. An extension of these measurements to 3He photo-disintegration is particularly interesting; there is theoretical motivation for the idea that there will be a phase transition, analogous to the quark-gluon plasma phase transition seen at RHIC, which will be particularly evident from the deuteron/3He comparison. The studies of possible nucleon structure modifications in the nucleus with 4He(e,e'p) will be extended with a newer, higher precision measurement. The quark structure of the nucleon, in particular the spin structure, will be studied with a new series of experiments utilizing semi-inclusive deep inelastic scattering. Also, a new measurement of elastic electron deuteron scattering tests the role of relativity in nuclear structure with unprecedented precision, and allows the neutron electric form factor to be determined.
In addition to this rich program centered at Jefferson Lab, we are embarking on a major new experimental effort in neutrino scattering at Fermilab. The NuMI intense neutrino beam was commissioned in 2004 at Fermilab, opening the way to a new generation of neutrino experiments. We are founding members of the Main INjector Experiment Neutrino-A experiment MINERνA. This experiment will use a compact, fully active scintillator detector to make high precision neutrino scattering measurements. Our group will be responsible for construction of major elements of the detector and software development. The experiment is expected to be begin data taking in 2008.
Professor Noémie Koller
The electromagnetic properties of low-lying nuclear states are very sensitive indicators of the underlying nuclear structure, and in particular, of the interplay between single particle and collective excitations which have been found to coexist even at very low energies. We carry out experiments designed to measure the magnetic dipole and electric quadrupole moments of very short lived, high spin, nuclear states, and of exotic nuclei far-from-stability. Radioactive beam facilities are being planned in the US which will produce abundant quantities of nuclei that are likely to display "new physics" highlighted by very different p-n interactions, different spin-orbit couplings and coexistence of rather exotic shapes. These experiments rely on the hyperfine interactions between the nuclei and the solid environment in which they are embedded. Thus, in addition to providing direct nuclear structure data, these experiments lead to detailed information on the fundamental interactions between ions and magnetic and non-magnetic solids. Experiments are performed at the Tandem Accelerator at Yale University, at the 88" cyclotron at the Lawrence Berkeley National Laboratory, and at the radioactive beam facility HIRBF at Oak Ridge National Laboratory.
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