# Nucleus Nucleus 2015

Jun 21 – 26, 2015
Dipartimento di Fisica ed Astronomia, Università di Catania
Europe/Rome timezone
All the plenary sessions will be transmitted in streaming on the web. From Monday, June 22nd, a link will be available <a href='http://www.streamago.tv/channel/54955/default/iframe/' target='blank'> here </a>

## Study of fusion-fission dynamics in $^{19}$F+$^{238}$U reaction

Not scheduled
20m
Aula Magna (Dipartimento di Fisica ed Astronomia, Università di Catania)

### Aula Magna

#### Dipartimento di Fisica ed Astronomia, Università di Catania

Via Santa Sofia, 64 95123, Catania, Italy
Oral presentation Fusion and Fission

### Speaker

Mr R Dubey (Inter University Accelerator Centre, New Delhi, India)

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\noindent{\underline{The 12th International Conference on Nucleus-Nucleus Collisions, June 21-26, 2015, Catania, Italy}}

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{\large \bf Study of fusion-fission dynamics in $^{19}$F+$^{238}$U reaction}
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{R. Dubey}$^{1,*}$, Gurpreet Kaur$^{2}$, Ish Mukul$^3$, Meenu Thakur$^2$, Tathagata Banerjee$^1$, Ruchi Mahajan$^2$, Davinder Siwal$^1$, N. Saneesh$^1$, A. Jhingan$^1$, M. B. Chatterjee$^{4}$ and
P. Sugathan$^1$
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{\em $^1$Inter University Accelerator Centre, Aruna Asaf Ali Marg, New Delhi - 110067, India} \
{\em $^2$Dept of Physics, Panjab University, Chandigarh - 160014, India}\
{\em $^3$Dept of Particle \& Astrophysics, Weizmann Institute of Science, Rehovot 76100, Israel}\
{\em $^4$Saha Institute of Nuclear Physics, Kolkata, West Bengal 700064, India}\
{\small \em $^*$rdube.iuac@gmail.com}
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% write your abstract hereThis is my abstract [1].
Over the years, a large number of experiments have been performed to study the dynamics of fusion-fission mechanism in heavy ion induced reactions. These studies are important for better understanding of the reaction dynamics involved in the formation of super heavy elements in laboratory. Apart from pure fusion-fission, the existence of pre-equilibrium fission (PEQ) and quasi-fission (QF) add further complexity to the reaction dynamics. They are found to be the competing reaction channels for light ion induced reactions with actinide targets. Though many studies have been performed in this mass region, there are still inconsistency in the results of many of these reactions. For example, the angular anisotropies of fission fragments measured in reactions $^{19}$F, $^{16}$O, $^{12}$C + $^{232}$Th, $^{238}$U [1,2,3] have been found inconsistent with the statistical saddle point model (SSPM) predictions. It has been reported that PEQ fission mechanism, i.e., departure from K equilibration before fission events might be responsible for these anisotropies. However for reactions of $^{19}$F, $^{16}$O, $^{12}$C on $^{232}$Th [4], the mass distribution of fragments showed evidence of QF, i.e., no mass equilibration before fission. In the recent work, presence of QF is evident in the reaction $^{18}$O+$^{232}$Th as compared to the $^{12}$C+$^{238}$U system[5]. In the present work, we performed the mass distribution of fission fragments in the reaction $^{19}$F+$^{238}$U where large anisotropy has been reported in angular distribution.

      Experiment was performed in the general purpose scattering chamber(GPSC) facility at Inter University Accelerator Centre (IUAC), New Delhi  using 15UD tandem accelerator. Pulsed beam of $^{19}$F with a repetition rate of 250 ns was bombarded on $^{238}$U targets with laboratory energy range of 80 to 120 MeV.  Two large area multi-wire proportional counters (MWPCs) were used to detect fission fragments.

Mass variance of fission fragments for $^{19}$F+$^{238}$U reaction has been measured around the sub-barrier energies.  Mass variance are found to be consistent with those found in systems $^{12}$C+$^{238}$U and $^{16}$O+$^{238}$U around sub-barrier energies. Similar trends of mass variance for reactions $^{19}$F, $^{16}$O,  $^{12}$C +  $^{232}$Th has been observed. Additionally, mass angle correlation measurements for $^{19}$F+$^{238}$U exhibits similar kind of behavior as $^{12}$C+$^{238}$U and $^{16}$O+$^{238}$U systems. Hence it can be concluded that, $^{19}$F, $^{16}$O, $^{12}$C + $^{232}$Th, $^{238}$U reactions exhibit departure from mass equilibration before fission process, i.e., QF mechanism will be significant part of the fission mechanism in these reactions.


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[1] J.C. Mein \emph{et al.},Phys. Rev. C {\bf}, 55, R995 (1997).\newline
[2] J. P. Lestone \emph{et al.}, Phys. Rev. C {\bf}, 56, R2907(1997).\newline
[3] V. S. Ramamurthy \emph{et al.}, Phys. Rev. Lett. {\bf},65, 25(1990).\newline
[4]T.K. Ghosh \emph{et al.}, Physics Letters B {\bf}, 627 (2005).\newline
[5]C.Yadav \emph{et al.}, Phys. Rev. C {\bf}, 86, 034606 (2012).\newline

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### Primary author

Mr R Dubey (Inter University Accelerator Centre, New Delhi, India)

### Presentation materials

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