Crystal Blocking Measurements of the Time Delay of Fission Induced by $^{32}\mathrm{S}$, $^{48}\mathrm{Ti}$, and $^{58}\mathrm{Ni}$ Bombardment of W

Crystal Blocking Measurements of the Time Delay of Fission Induced by ${}^{32}S$ , ${}^{48}{Ti}$ , and ${}^{58}{Ni}$ Bombardment of W

J. U. Andersen, J. Chevallier, J. S. Forster, S. A. Karamian, C. R. Vane, J. R. Beene, A. Galindo-Uribarri, J. Gomez del Campo, H. F. Krause, E. Padilla-Rodal, D. Radford, C. Broude, F. Malaguti, and A. Uguzzoni

Phys. Rev. Lett. 99, 162502 – Published 15 October 2007

Abstract

The time delay in fission induced by bombardment of W with 180 MeV ${}^{32}S$ , 240–255 MeV ${}^{48}{Ti}$ , and 315–375 MeV ${}^{58}{Ni}$ has been measured by observation of crystal blocking. There is a clear narrowing and a small increase in the minimum yield of the angular dips for fission compared with scaled dips for elastically scattered ions. This is interpreted as a fission delay of about 2 as, only weakly dependent on energy and atomic number. The delay is longer by 1 to 2 orders of magnitude than obtained from standard interpretations of measurements of prescission neutrons and giant-dipole-resonance gamma rays and from calculations of the nuclear dynamics in heavy-ion reactions.