Study of transverse excitations in the giant resonance region of 236U using the (e,e'f) reaction.

We measured 236U(e,e'f) coincidence cross sections at six values of the momentum transfer (qeff ~ 0.50, 0.72, 0.84, 0.95, 0.97 and 1.16 fm-1 ) at both forward (Oe = 50°, 75° , 110°) and backward angles (Oe = 160°), over an excitation energy range from 2 to 18 MeV. The backward angle data were taken with the aim of enhancing the transverse part of the cross section, which contains contributions from currents other than the convection currents. Due to the necessity to treat the data in the DWBA no model-independent multipole decomposition was possible. The data were integrated over the fission angle and compared with the calculations using both the Tassie model and the QRPA form factors. At the two lowest momentum transfers the data are well described by the inclusion of the electric multipoles of L = 0, 1, 2 and 3 transitions. For higher momentum transfers and backward angles higher multipolarities are needed. Comparison of our results with the forthcoming QRPA calculations for uranium will show the importance of the effects of the magnetic excitations in the description of the collective states. We developed and constructed a 47r Parallel Plate Avalanche Detector array for the detection of fission fragments . It consists of up to 13 PPADs mounted on a modular geodesic dome. An extensive study of the behavior of PPADs in the electron beam environment was done, with the electron beam currents between 200 nA and 8 11A.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Physics

Year dc:date

2011

Author dc:creator

• Serdarevic, Amra

Contributors dc:contributor

• Papanicolas, Costas N.

• (e,e'f) reaction
• Uranium-236 (236U)
• uranium
• transverse excitations

Statement dc:rights

• Copyright 1993 Amra Serdarevic

Language dc:language

en

Identifier

3644326

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/18864