Short Note
Strong enhancement of two-neutron transfer in the system 206Pb+118Sn
I. Peter1,3 - W. von Oertzen1,2 - H.G. Bohlen2 - A. Gadea3 - B. Gebauer2 - J. Gerl3 - M. Kaspar3 - I. Kozhoukharov3 a - T. Kröll3 - M. Rejmund3 - C. Schlegel3 - S. Thummerer2 - H.J. Wollersheim3
1 Freie Universität Berlin, Fachbereich Physik, Arnimallee 14, D-14195 Berlin,
Germany
2 Hahn-Meitner-Institut Berlin, Glienicker Strasse 100, D-14109 Berlin, Germany
3 Gesellschaft für Schwerionenforschung Darmstadt, Planckstrasse 1, D-64291 Darmstadt,
Germany
Received: 18 December 1998 / Revised version: 23 February 1999 Communicated by D. Schwalm
Abstract
One and two neutron transfer has been measured in the heaviest asymmetric
nuclear system with semi magic nuclei showing superfluid properties,
in 206Pb+118Sn collisions at an energy well below the Coulomb
barrier with scattering orbits covering the largest angles. Particle-
coincidence techniques using 5 Euroball-Cluster detectors (EB) combined in a
set-up with the Heidelberg-Darmstadt NaI-Crystal Ball (CB) have been used.
Transfer channels are identified with EB via their known -decays
of the lowest excited states.
Using the unique feature of the set-up with the CB,
transfer to well defined final states with known quantum numbers
(without feeding) are selected using the high efficiency
multiplicity filter of the CB (no second -ray).
The data are analysed using the
semiclassical approach and transfer probabilities are obtained.
The enhancement for the two-neutron transfer populating the
low lying superfluid 2+ state in 120Sn (and 116Sn), while the
Pb-branch is in the groundstate is deduced by comparison with the strongest
single neutron transfer transition. Large enhancements (EF
103)
are observed. This is the first direct measurement of enhancement for a heavy
nuclear binary system with experimentally separated levels
suggesting a strong contribution from superfluid pair transfer.
PACS
25.70.Hi Transfer reactions
Copyright Springer-Verlag
