CERN Accelerating science

PES of $^{178}$Pt in the ($Q_{20}$, $Q_{30}$) plane (a) and in the ($Q_{30}$, $Q_{40}$) plane at $Q_{20}=190$\,b (b) obtained in D1S. The solid thick line in (a) indicates the static fission path obtained by the local minimization of PES. Dashed lines in (b) indicate the symmetric PESs corresponding to compact (smaller $Q_{40}$) and elongated (larger $Q_{40}$) fragments. The minimum corresponding to the static fission path in (a) is marked by the red dot.

(a) Two-dimensional TOF1-TOF2 raw-data spectrum for coincident events at $E_{\rm beam}=170$ MeV. Events in the black contour are from fission; remaining events are from the projectile-target scattering. (b) Summed energy signals from the MWPC detectors for $E_{\rm beam}=170$ MeV plotted against the difference in their timing signals (coincidence with MCPs not demanded). Contoured are fission events producing more ionization in detectors, due to their significantly larger ionic charge states and, hence, higher effective charges that scattered beam/target nuclei. (c) FF velocities after calibration with the scattered $^{36}$Ar beam, corrected for attenuation in the target and TOF detectors. The inset shows a typical (free) fit of the data at $E_{\rm beam}=170$ MeV. (d) Events from (a) represented in terms of their total kinetic energy and mass both calculated from experimentally obtained velocities, assuming fission process as the only events' origin. Group of events in the plot's center is coincident with data in contours in (a) and (b).

PES of $^{178}$Pt in the ($Q_{20}$, $Q_{30}$) plane calculated in UNEDF-HFB. The solid thick line indicates the static fission path obtained by the local minimization of PES. To illustrate the shapes on the way to fission, and the emergent pre-fragments, the neutron localization functions~\cite{Zhang2016,Sadhukhan2017} corresponding to various intrinsic configurations along the asymmetric (ABCD) and symmetric (ABcd) paths are plotted.

(a) TKE distribution for $E_{\rm beam}=$170 MeV (projection of (b) onto the TKE-axis) de-convoluted into two components with derived positions of ${\rm TKE}^{\rm high}$ and ${\rm TKE}^{\rm low}$, shown by dotted horizontal lines, see text for details. (b) TKE -- FF mass correlation obtained with events' selection as in Figs.~\ref{fig1}a-b. TKE scale is identical for both (a) and (b). Mass spectra gated on events above ${\rm TKE}^{\rm high}$ (c) and below ${\rm TKE}^{\rm low}$ (d) fitted with a double- and single-Gaussian unconstrained function; fit results given by red lines. (e-g) Total FFMDs at different CN excitation energies (cf. Table~\ref{tab:table1}). Solid red lines result from a fit with fixed symmetric and asymmetric mode positions. Blue and black dashed lines show the asymmetric and symmetric fit components, respectively. Experimental mass resolution is $\sigma^{\rm exp}_{A}=2.9$\,amu, as deduced from the width of the $^{36}$Ar peak (not shown).