Development of optically pumped polarized jet targets for use in heavy-ion reaction studies

The development of a laser optically pumped nuclear spin aligned target of /sup 151/ /sup 153/Eu is outlined. The current status of this project, together with the unique macroscopic heavy-ion reaction physics may be addressed using this target, is given. 14 references

Nuclear Ground State Observables and QCD Scaling in a Refined Relativistic Point Coupling Model

We present results obtained in the calculation of nuclear ground state properties in relativistic Hartree approximation using a Lagrangian whose QCD-scaled coupling constants are all natural (dimensionless and of order 1). Our model consists of four-, six-, and eight-fermion point couplings (contact interactions) together with derivative terms representing, respectively, two-, three-, and four-body forces and the finite ranges of the corresponding mesonic interactions. The coupling constants have been determined in a self-consistent procedure that solves the model equations for representative nuclei simultaneously in a generalized nonlinear least-squares adjustment algorithm. The extracted coupling constants allow us to predict ground state properties of a much larger set of even-even nuclei to good accuracy. The fact that the extracted coupling constants are all natural leads to the conclusion that QCD scaling and chiral symmetry apply to finite nuclei.Comment: 44 pages, 13 figures, 9 tables, REVTEX, accepted for publication in Phys. Rev.

Detection of internally deposited actinides. Part III. Recent background studies at ORNL

It has been apparent from accumulated data at ORNL that the low-energy (less than 100 keV) phoswich background spectrum in the iron-shielded counting facility has components, possibly including a line below 15 keV, whose magnitudes show considerable variability. We have used a planar intrinsic Ge detector designed especially for measuring low-energy photons for background study as part of an evaluation of such a device for in vivo $sup 239$Pu measurement. The spectrum that was observed consisted of a continuum upon which were superimposed discrete lines including a strong line at 10.35 keV in addition to the well-known lines from Pb X rays. Detectable also were X rays that corresponded to K-lines of several of the products of the naturally occurring radioactive decay series. Background spectra are presented and the implications of their variability are discussed. (auth

Laser-optical studies of the spontaneous-fission isomer /sup 240m/Am

Improved optical pumping experiments on the /sup 240m/Am fission isomer have been performed using the Laser Induced Nuclear Polarization (LINUP) technique. Results of these experiments are discussed in terms of the constraints they place on the spectroscopic properties of /sup 240m/Am. In addition, a quantitative analysis of the isomer shift in terms of nuclear shape is undertaken making use of recent muonic x-ray data on /sup 241/Am and /sup 243/Am

Study of the fission isomer /sup 240m/Am (S. F. ) using laser-induced nuclear polarization. [Cross section of /sup 238/U(/sup 7/Li,5n) at 48 MeV]

The optical isomer shift was measured for the spontaneously fissioning isomer /sup 240m/Am. This shift is approximately 27 times greater than the /sup 241/Am-/sup 243/Am isotope shift, and confirms the conventional identification of fission isomers with large deformation. The measured isomer shift is consistent with a nuclear quadrupole moment of 30.4 b, in agreement with theoretical expectations. 2 figures. (RWR

Development of a laser optically pumped polarized target for use in heavy-ion physics. [/sup 151/ /sup 153/Eu]

Important micro- and macroscopic details of heavy-ion reactions may be explicitly determined when nuclear spin aligned (polarized) targets are used. For deformed nuclei, the orientation of the symmetry axis of the nuclear density distribution is determined by the nuclear spin orientation. Polarized targets would thus allow experiments to be performed as a function of the orientation of the symmetry axis of the nuclear density distribution. A polarized target of /sup 151/ /sup 153/Eu is being developed at Oak Ridge and is based on laser depopulation optical pumping. A spatially defined target is provided by a supersonic gas jet and consists of Eu atoms seeded into an inert carrier gas. Detailed time-dependent optical-pumping calculations predict approx. = 90% nuclear spin polarization in a Eu target with an expected thickness in excess of 10/sup 15/ atoms/cm/sup 2/. We present some of the effects that will be observable in heavy-ion reactions when deformed polarized targets are used