Fission-fragment Spectroscopy

Nuclear fission provides a prolific source of neutron-rich nuclei. The tremendous improvement in the resolving power of Gammasphere has led to significant progress in understanding nuclear structure of neutron-rich fission products as well as knowledge of fission dynamics [1,2]. The drawbacks of using fission sources on thick-backings can be eliminated by using the fission-fragment $\gamma $-ray coincident technique that we have developed using CHICO plus Gammasphere[3,4,5] . Our technique adds mass selectivity, identifies the fission fragment from which the $\gamma $-rays originate significantly improving the sensitivity for study of neutron-rich nuclei, and extends spectroscopic study to spins as high as 24, that is, the band crossing region. We extended the scope of the study of neutron-rich nuclei by studying fission fragments using specific fusion-fission reactions to populate neutron-rich nuclei in a series of seven publications during 2002-2005 and listed in the publication list of neutron-rich nuclear studies. This work led to the Ph.D. (Rochester) thesis of M.W. Simon.

Radioactive beam facilities such as ISAC II and CARIBU now have replaced this fission-fragment technique for the proposed studies of neutron rich nuclei.

1) I. Ahmad and W. Phillips, Rep. Prog. Phys. 58, 1415 (1995).

2) J. Hamilton, A.V. Ramayya, S.J. Zhu, G.M. Ter-Akopian, Yu.Ts. Oganessian, J.D. Cole, J.O. Rasmussen, and M.A. Stoyer, Prog. Part. Nucl. Phys. 35, 635 (1995).

3) M.W. Simon, D. Cline, C.Y. Wu, R.W. Gray, M.A. Stoyer, K. Vetter, A. Macchiavelli, K. Gregorich, R.W. Macleod, S. Asztalos, J. Gilat, C.T. Zhang, and P. Bhattacharyya, Proc. Of the Int. Conf. On Fission and Properties of Neutron Rich Nuclei, Sanibel Island, FL., Ed. J.H. Hamilton and A.V. Ramayya, (World Scientific Publishing Co., 1998), p. 270.

4) M.W. Simon, Ph.D. thesis, University of Rochester (1999) (unpublished).

5) M.W. Simon, D. Cline, C.Y. Wu, R.W. Gray, R. Teng, and C. Long, Nucl. Instrum. Methods in Phys. Res. A452, 205 (2000).