Time delays in heavy-ion-induced fission of medium-Z nuclei, measured by crystal blocking

J. U. Andersen, J. Chevallier, J. S. Forster, S. A. Karamian, C. R. Vane, J. R. Beene, C. J. Gross, H. F. Krause, J. F. Liang, D. Shapira, A. Uguzzoni

Research output: Contribution to journalArticlepeer-review


Time delays in fission induced by bombardment of Mo with 170- and 180-MeV 32S, 225- and 240-MeV 48Ti, and 300-MeV 58Ni have been measured by observation of crystal blocking of fission fragments. In contrast to earlier measurements with a W target, the results are consistent with fission of a compound nucleus in competition with mainly neutron emission. Most of the fissions happen on a time scale much shorter than attoseconds but there is a significant component of fission with much longer lifetimes. The measurements are reproduced with a standard statistical model, including a Kramers correction to fission widths from the viscosity of hot nuclear matter. These new results support the interpretation of our earlier measurements with a W target, which indicate that there is a transition in heavy-ion-induced fission at large atomic number and mass, from multichance fission in the standard Bohr-Wheeler picture to fission without formation of a compound nucleus. The process is slowed down by nuclear viscosity, with measured delays of order attoseconds.

Original languageEnglish
Article number044609
JournalPhysical Review C - Nuclear Physics
Issue number4
StatePublished - 13 Apr 2012
Externally publishedYes

ASJC Scopus subject areas

  • Nuclear and High Energy Physics


Dive into the research topics of 'Time delays in heavy-ion-induced fission of medium-Z nuclei, measured by crystal blocking'. Together they form a unique fingerprint.

Cite this