Eur. Phys. J. A (2010) 43: 251-259
https://doi.org/10.1140/epja/i2010-10911-5

Regular Article - Experimental Physics

Investigation of deep inelastic reactions in ²³⁸U + ²³⁸U at Coulomb barrier energies

¹ GANIL (IN2P3/CNRS - DSM/CEA), B.P. 55027, 14076, Caen Cedex 5, France
² GSI Helmholtzzentrum für Schwerionenforschung GmbH, D-64291, Darmstadt, Germany
³ VEC Center I/AF, 700064, Bidhan Nagar, Kolkata, India
⁴ SPhN - CEA/DSM/DAPNIA, Gif-sur-Yvette Cedex, France
⁵ CEA, DAM, DIF, F91297, Arpajon, France
⁶ SUBATECH, 4 rue Alfred Kastler, B.P 20722, 44307, Nantes Cedex, France
⁷ FLNR - JINR, 141980, Dubna, Russia

^* e-mail: s.heinz@gsi.de

Received: 2 September 2009
Revised: 27 November 2009
Published online: 26 January 2010

Abstract

We investigated deep inelastic reactions in ²³⁸U + ²³⁸U collisions at 6.09, 6.49, 6.91, 7.1 and 7.35×A MeV at the VAMOS spectrometer (GANIL). A large transfer of neutrons and protons was observed at all beam energies. For a transfer of more than 10 nucleons the total kinetic energy of the detected fragments becomes independent of the beam energy and reaches values far below the Coulomb barrier for spherical fragments. This points to the formation of a di-nuclear system in the entrance channel which develops an elongated shape and a strong neck. For such reactions we expect an enhanced lifetime of the di-nuclear system which is significantly longer than the time scale for elastic and quasi-elastic reactions. Different theoretical approaches predict delay times of more than 5×10^-21 s for a subset of our data.