New Spontaneous Fission Mode for252Cf: Indication of Hyperdeformed144,145,146Baat Scission

From $\gamma$-ray coincidence studies following spontaneous fission of ${}^{252}\mathrm{Cf}$, direct measurements of yields and neutron multiplicities were made for Sr-Nd, Zr-Ce, Mo-Ba, Ru-Xe, and Pd-Te correlated pairs. A strong enhancement of the 7-10 neutron channels for Mo-Ba pairs is observed. A new fission mode associated with the enhanced neutron yields is identified. These data can be interpreted in terms of one or more of ${}^{144,145,146}\mathrm{Ba}$ being hyperdeformed at scission. Mean field calculations predict a hyperdeformed third minimum in ${}^{252}\mathrm{Cf}$ and an extremely deformed ${}^{146}\mathrm{Ba}$ fragment at scission.