Fundamental nucleon-nucleon interaction: probing exotic nuclear structure using GEANIE at LANCE/WNR
The initial goal of this project was to study the in-medium nucleon-nucleon interaction by testing the fundamental theory of nuclear structure, the shell model, for nuclei between {sup 8}Zr and {sup 100}Sn. The shell model predicts that nuclei with ''magic'' (2,8,20,28,40,50, and 82) numbers of protons or neutrons form closed shells in the same fashion as noble gas atoms [may49]. A ''doubly magic'' nucleus with a closed shell of both protons and neutrons has an extremely simple structure and is therefore ideal for studying the nucleon-nucleon interaction. The shell model predicts that doubly magic nuclei will be spherical and that they will have large first-excited-state energies ({approx} 1 to 3 MeV). Although the first four doubly-magic nuclei exhibit this behavior, the N = Z = 40 nucleus, {sup 80}Zr, has a very low first-excited-state energy (290 keV) and appears to be highly deformed. This breakdown is attributed to the small size of the shell gap at N = Z = 40. If this description is accurate, then the N = Z = 50 doubly magic nucleus, {sup 100}Sn, will exhibit ''normal'' closed-shell behavior. The unique insight provided by doubly-magic nuclei from {sup 80}Zr to {sup 100}Sn has made them the focus of tremendous interest in the nuclear structure community. However, doubly-magic nuclei heavier than {sup 56}Ni become increasingly difficult to form due to the coulomb repulsion between the protons which favors the formation of neutron-rich nuclei. The coulomb repulsion creates a ''proton drip-line'' beyond which the addition of any additional bound protons is energetically impossible. The drip line renders the traditional experimental technique used in their formation, the heavy-ion reaction, less than ideal as a method of forming doubly-magic nuclei beyond {sup 80}Zr. The result has been a lack of an new spectroscopic information on doubly magic nuclei in more than a decade [lis87]. Furthermore, uncertainties in reaction dynamics modeling made it difficult for the nuclear science community to predict the cross section or forming these highly-neutron deficient nuclei. Therefore, we decided to try a new approach to forming highly-neutron deficient nuclei with the hope of both gaining spectroscopic information for nuclei near {sup 100}Sn, and also gaining insight into reaction dynamics at high (E{sub x} > 200 MeV) incident nucleon energy.
- Research Organization:
- Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
- Sponsoring Organization:
- US Department of Energy (US)
- DOE Contract Number:
- W-7405-ENG-48
- OSTI ID:
- 15006435
- Report Number(s):
- UCRL-ID-137793; TRN: US0400766
- Resource Relation:
- Other Information: PBD: 25 Feb 2000
- Country of Publication:
- United States
- Language:
- English
Similar Records
Spectroscopic quadrupole moments in124$\mathrm{Xe}$
Shell structure of superheavy nuclei in self-consistent mean-field models
Related Subjects
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
ATOMS
BREAKDOWN
COULOMB FIELD
CROSS SECTIONS
HEAVY ION REACTIONS
MAGIC NUCLEI
NEUTRONS
NUCLEAR STRUCTURE
NUCLEI
NUCLEON-NUCLEON INTERACTIONS
NUCLEONS
PROTONS
SHELL MODELS
SIMULATION
TESTING