Experimental Nuclear Physics: Nuclear Structure

Faculty: J. H. Hamilton and A. V. Ramayya
Research Associates: J. K. Hwang, W. Krolas, Y. X. Luo

Adjunct Professor: W. A. Greiner (Institute for Theoretical Physics, University of Frankfurt)
Adjoint Professors: A. Faessler (Director, Institute for Theoretical Physics, University of Tübingen);
                                 R. V. F. Janssens (Argonne National Laboratory)

Graduate Students: C.J. Beyer, D. Fong, P. Gore, K. Li

Low energy nuclear physics at Vanderbilt University addresses the structure of atomic nuclei, with special emphasis on both proton and neutron rich nuclei far from the stable ones found in nature. This field encompasses some 3000 experimental and theoretical physicists working at the Universities and National Laboratories.

Many empirical models of nuclear physics have provided a realistic framework for our understanding of a rich array of experimentally observed phenomena such as shell structure, collective rotations and vibrations of many nucleons in the nucleus, nuclear shapes and the shape co-existence of different shapes in the same nucleus. As in any physical system, pushing nuclei to the extreme limits reveals new features and leads to new insights and understandings.

Many of the intellectual challenges that confront us today can only be answered with forefront accelerators, sophisticated detector arrays, and high-powered computers. At Vanderbilt the nuclear structure group produce nuclei out to the extremes including the limits of stability of proton rich nuclei and investigate their behavior at high excitation energies and angular momentum and their exotic decay modes and binding energies. To that end a new generation Recoil Mass Spectrometer was built at the Holifield Radioactive Ion Beam Facility and a variety of sophisticated detectors developed for use with it.

Recent research has been carried out with heavy-ion accelerators at Oak Ridge National Laboratory, Argonne National Laboratory, Lawrence Berkeley Laboratory in US and Flerov Laboratory for Heavy Ion Reactions (Dubna, Russia).
Some of the discoveries by our group include (a) existence of spherical and deformed shapes in the same nucleus; (b) super-, hyper and octupole deformation; (c) cold and hot binary and ternary fission modes; (d) many neutron rich isotopes; (e) proton radioactivity, and (f) deformed magic numbers at 38 and 60.

The research group has an international reputation and regularly presents invited papers at international conferences (95 invited papers at 75 international conferences in 11 countries in the last five years). There are active collaborations with scientists from Oak Ridge National Laboratory, Argonne National Laboratory, Lawrence Livermore National Laboratory, Idaho National Engineering Laboratory, and members of the UNRIB Consortium of 12 major universities at ORNL in US and from Brazil, China, Germany, Italy, Poland, Romania, Russia and Slovakia. The research is supported by the U.S. Department of Energy.

Graduate students working in the group receive financial support as Research Assistants. Some students spend 1-2 years at Oak Ridge or Argonne doing their thesis research. All students have opportunities to interact with scientists from all over the world, to travel to international conferences, and to speak at conferences of the American Physical Society. Travel is supported by the grant. Members of this group host international conferences periodically.

There is a strong theoretical group at Vanderbilt and, as well, the group supports short term visits (1-3 months) by leading theoretical scientists from the U.S. and abroad to work in the group. Over 60 Ph.D.'s have been awarded in experimental nuclear physics by our group and over 800 papers published in leading journals and research books.

The eleventh International Conference organized and hosted by the group will be at Sanibel, FL, in November, 2002, the third International Conference on Fission and Properties of Neutron-rich Nuclei.

The Vanderbilt nuclear structure group is the organizer of the Joint Institute for Heavy Ion Research at the Holifield Heavy Ion Research (HHIRF) in Oak Ridge. This is a joint venture of Vanderbilt, the University of Tennessee/Knoxville, Oak Ridge National Laboratory, and the State of Tennessee. The Institute buildings ($950,000 total costs) provide living accommodations and offices for outside users and a conference center. The Institute brings over 50 distinguished scientists each year to Tennessee from all over the world to work in research with our students and faculty. One member of our group (JHH) is the Director of the Joint Institute.

Some of publications include:

1. "Observation of 10Be emission in the cold ternary spontaneous fission of 252Cf "
Ramayya AV, Hwang JK, Hamilton JH, Sandulescu A, Florescu A, Ter-Akopian GM, Daniel AV, Oganessian YT, Popeko GS, Greiner W, Cole JD,
Phy. Rev. Lett. 81, 947-950 (1998)

2. "Octupole correlations in neutron-rich 143,145Ba and a Type of Superdeformed Band in 145Ba"
Zhu SJ, Hamilton JH, Ramayya AV, Jones EF, Hwang JK Wang MG, Zhang XQ, Gore PM, Peker LK, Drafta G, Babu BRS, Ma WC, Long GL, Zhu LY, Gan CY, Yang, LM, Sakhaee M, Li M, Deng JK, Ginter TN, Beyer CJ Kormicki J, Cole JD, Aryaeinejad R, Drigert MW, Rasmussen JO, Asztalos S, Lee IY, Macchiavelli AO, Chu SY, Gregorich KE, Mohar MF, Ter-Akopian GM, Daniel AV, Oganessian YT, Donangelo R, Stoyer MA, Lougheed RW, Moody KJ, Wild JF, Prussin SG, Kliman J, and Griffin HC,
Phys. Rev. C60, R05134 (1999)

3. "Shape coexistence phenomena in medium mass nuclei "
Petrovici A, Schmid KW, Faessler A, Hamilton JH, Ramayya AV,
Prog. in Part. and Nucl. Phys. 43, 485-535 (1999)

4. "Performance of the Recoil Mass Spectrometer and its detector systems at the Holifield Radioactive Ion Beam Facility"
Gross CJ, Ginter TN, Shapira D, Milner WT, McConnell JW, James AN, Johnson JW, Mas J, Mantica PF, Auble RL, Das JJ, Blankenship JL, Hamilton JH, Robinson RL, Akovali YA, Baktash C, Batchelder JC, Bingham CR, Brinkman MJ, Carter HK, Cunningham RA, Davinson T, Fox JD, Galindo-Uribarri A, Grzywacz R, Liang JF, MacDonald BD, MacKenzie J, Paul SD, Piechaczek A, Radford DC, Ramayya AV, Reviol W, Rudolph D, Rykaczewski K, Toth KS, Weintraub W, Williams C, Woods PJ, Yu CH, Zganjar EF,
Nucl. Inst. & Meth. in Phys. Res. Sec. A450, 12-29 (2000)

5. "Proton Emission from 150Lu"
Ginter TN, Batchelder JC, Bingham CR, Gross CJ, Grzywacz R. Hamilton JH, Janas Z, Karny M, Kim SH, Mas JF, McConnell JW, Piechaczek A, Ramayya AV, Rykaczewski K, Semmes PB, Szerypo J, Toth KS, Wadsworth R, Yu C-H, Zganjar EF,
Phys Rev. C61, 014308,(2000)

6. "Identification of neutron h(11/2) bands in 121Cd, 123Cd "
Hwang JK, Beyer CJ, Ramayya AV, Hamilton JH, Zhang XQ, Rasmussen JO, Luo YX, Wu SC, Ginter TN, Lee IY, Folden CM, Fallon P, Zielinski P, Gregorich KE, Macchiavelli AO, Stoyer M, Asztalos SJ,
J. of Phys. G28, L9-L14 (2002)

7. "Cold and hot binary and ternary fission yields in the spontaneous fission of 252Cf "
Hamilton JH, Ramayya AV, Hwang JK, Ter-Akopian GM, Daniel AV, Rasmussen JO, Wu SC, Donangelo R, Beyer CJ, Kormicki J, Zhang XQ, Rodin AM, Fomichev AS, Popeko GS, Kliman J, Krupa L, Jandel M, Oganessian YT, Chubarian G, Seweryniak D, Janssens RVF, Ma WC, Piercey RB, Greiner W, Cole JD,
Phys. of Atom. Nucl. 65, 645-652 (2002)

8. "First observation of the drip line nucleus 140Dy: Identification of a 7 mu s K isomer populating the ground state band "
Krolas W, Grzywacz R, Rykaczewski KP, Batchelder JC, Bingham CR, Gross CJ, Fong D, Hamilton JH, Hartley DJ, Hwang JK, Larochelle Y, Lewis TA, Maier KH, McConnell JW, Piechaczek A, Ramayya AV, Rykaczewski K, Shapira D, Tantawy MN, Winger JA, Yu CH, Zganjar EF, Kruppa AT, Nazarewicz W, Vertse T,
Phys. Rev. C65, R031303 (2002)

9. "Level structure of 141Ba and 139Xe and the level systematics of N=85 even-odd isotones "
Luo YX, Rasmussen JO, Hamilton JH, Ramayya AV, Hwang JK, Beyer CJ, Zhu SJ, Kormicki J, Zhang XQ, Jones EF, Gore PM, Ginter TN, Gregorich KE, Lee IY, Macchiavelli AO, Zielinski P, Folden CM, Fallon P, Ter-Akopian GM, Oganessian YT, Daniel AV, Stoyer MA, Cole JD, Donangelo R, Wu SC, Asztalos SJ,
Phys. Rev. C66, 014305 (2002)

10. "Particle-hole excited states in 133Te"
Hwang JK, Ramayya AV, Hamilton JH, Beyer CJ, Rasmussen JO, Luo YX, Wu SC, Ginter TN, Folden CM, Fallon P, Zielinski PM, Gregorich KE, Macchiavelli AO, Stoyer M, Asztalos SJ, Covello A, Gargano A,
Phys. Rev. C65, 034319 (2002)