Gammasphere is a very sensitive detector of gamma rays submitted from nuclei.

The core of an atom is the nucleus. Existing models of nuclear structure have been challenged recently by the discovery at several national laboratories of nuclei with extended shapes and other unusual characteristics. These properties were observed in nuclei at the extremes of excitation energy, angular momentum, deformation, and other parameters. For instance, superdeformed nuclei with a 2:1 axis ratio were found that spin very rapidly and exhibit identical gamma-ray decay properties. Other nuclei have a diffuse "halo" of loosely bound neutrons. These properties, found only in laboratories on Earth, may be important in the synthesis of heavier elements in giant and exploding stars. Evidence also has been found for superheavy nuclei, which may be the first indication of the long-sought "island of stability" beyond the previously known nuclei found in nature (i.e., uranium). These studies have been conducted at Argonne, Lawrence Berkeley, and Oak Ridge national laboratories.

Scientific Impact: Studies of unstable isotopes (different forms of chemical elements) helps scientists understand the genesis of elements in stars and evolution of stellar systems. Nuclei with extended shapes and other properties near the extremes also test existing models and fundamental theories of the nucleus.

Social Impact: These studies help answer questions about the constituents and history of the universe, extending human understanding of nature and contributing to improvements in science education. In addition, although basic research is by definition a search for new knowledge without regard to its practical implications, such work often contributes to technologies with commercial value; examples include computers, lasers, and cancer treatments.

Reference: "Observation of a Discrete-Line Superdeformed Band up to 60 h in 152D," P.J. Twin et al., Phys Rev. Lett. 55: 1380 (1986); "Superdeformed Shapes at High Angular Momentum," P.J. Nolan and P.J. Twin, Ann. Rev. Nucl. Part. Sci. 38: 533-62 (1988); "Superdeformed Nuclei," R.V.F. Janssens and T-L. Khoo, Ann. Rev. Nucl. Part. Sci. 38 (1988).

URL: http://www-gam.lbl.gov

Technical Contact: Dr. Paul Fallon, pfallon@lbl.gov

Press Contact: Jeff Sherwood, DOE Office of Public Affairs, 202-586-5806

SC-Funding Office: Office of High Energy and Nuclear Physics