FU Berlin Digitale Dissertation
Ingo Peter : Enhanced neutron-pair transfer between superfluid heavy nuclei Verstärkter Neutronen-Paar Transfer zwischen superfluiden schweren Kernen
|Abstract| |Table of Contents| |More Information|

Abstract In this study multiple Coulomb-excitation and neutron-transfer reactions were investigated in the system 206Pb+118Sn using two different bombarding energies below the Coulomb-barrier. The experiment was performed at the accelerator UNILAC at the Gesellschaft für Schwerionenforschung in Darmstadt (GSI) with the experimental set-up consisting of five EUROBALL-Cluster detectors (EB) and the Heidelberg-Darmstadt crystal-ball (CB) for measuring gamma-rays and in addition three parallel plate counters for measuring the recoil nuclei. The experimental technique was to detect in coincidence one backscattered Sn-isotope and a photon in at least one EB-detector. Gamma-transitions following multiple inelastic excitation as well as one- and two-neutron transfer could be observed. The intensities of the transitions were used in a semiclassical approach to determine absolute reaction-probabilities as a function of the distance of closest approach of the two nuclei in the reaction. The probabilities of the gamma-transitions following inelastic excitation could be explained with Coulomb-excitation calculations within the accuracy of the in the calculation used reduced matrix elements. By comparison of the probabilities of the transitions following one- and two-neutron transfer, enhanced two-neutron transfer could be observed, expressed in terms of the enhancement factor EF. The high efficiency of the CB in measuring the total gamma-multiplicity and gamma-sum energy of a reaction made it possible to select "super-cold" transfer and thus to determine for the first time an enhancement factor referring to well defined states of both partner nuclei. The measured enhancement factor was EF=900 and independent of the bombarding energy. Furthermore for the first time a direct comparison with theoretical work of Broglia et al. [bro78] was possible, which explains an enhancement of this order with the superfluid properties, specifically the configuration mixing, of the nuclei in their ground states and first excited states.

Table of Contents Download the whole PhDthesis as a zip-tar file or as zip-File For download in PDF format click the chapter title Titel und Inhaltsverzeichnis 1. Einleitung 2. Theoretische Grundlagen 3. Experiment 4. Datenaufbereitung 5. Ergebnisse und Diskussion 6. Zusammenfassung Literaturverzeichnis

More Information:
Online available:	http://www.diss.fu-berlin.de/1999/12/indexe.html
Language of PhDThesis:	german
Keywords:	transfer, gamma-spectroscopy, neutron, heavy ion, pairing, superfluidity, Euroball
DNB-Sachgruppe:	29 Physik, Astronomie
Classification PACS:	25.70.Hi
Date of disputation:	06-Jan-1999
PhDThesis from:	Fachbereich Physik, Freie Universität Berlin
First Referee:	Prof.Dr. Wolfram von Oertzen
Second Referee:	Prof.Dr. Ta-chung Meng
Contact (Author):	i.peter@gsi.de
Contact (Advisor):	oertzen@hmi.de
Date created:	23-Feb-1999
Date available:	24-Feb-1999

 

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