Stability and production of superheavy nuclei
Abstract
Beyond uranium heavy elements rapidly become increasingly unstable with respect to spontaneous fission as the proton number Z increases, because of the disruptive effect of the longrange Coulomb force. However, in the region just beyond Z=100 magic proton and neutron numbers and the associated shell structure enhances nuclear stability sufficiently to allow observation of additional nuclei. Some thirty years ago it was speculated that an island of spherical, relatively stable superheavy nuclei would exist near the next doubly magic protonneutron combination beyond ^{208}Pb, that is, at proton number Z=114 and neutron number N=184. Theory and experiment now show that there also exists a rock of stability in the vicinity of Z=110 and N=162 between the actinide region, which previously was the end of the peninsula of known elements, and the predicted island of spherical superheavy nuclei slightly southwest of the magic numbers Z=114 and N=184. We review here the stability properties of the heavy region of nuclei. Just as the decay properties of nuclei in the heavy region depend strongly on shell structure, this structure also dramatically affects the fusion entrance channel. The six most recently discovered new elements were all formed in coldfusion reactions. We discuss here the effect of the doubly magic structure of the target in coldfusion reactions on the fusion barrier and on dissipation.
 Publication:

Tours Symposium on Nuclear Physics III
 Pub Date:
 February 1998
 DOI:
 10.1063/1.55136
 arXiv:
 arXiv:nuclth/9709016
 Bibcode:
 1998AIPC..425...75M
 Keywords:

 27.90.+b;
 21.60.Cs;
 25.70.Jj;
 220<
 =A;
 Shell model;
 Fusion and fusionfission reactions;
 Nuclear Theory
 EPrint:
 10 pages. LaTeX with AIP style file aipproc2.sty. 10 figures not included here. Presented at Tours Symposium on Nuclear Physics III, Tours, France, September 25, 1997. To be published in symposium proceedings by American Institute of Physics. Complete cameraready PostScript version with all figures inserted available at http://t2.lanl.gov/publications/publications.html or at ftp://t2.lanl.gov/pub/publications/tsnp97