Nuclear structure in 16O measured with (e,e´γ) coincident electron scattering

Some long-standing problems in nuclear structure were studied in 160 using the ( e,e'1) coincident electron scattering probe. Data at two momentum transfers ( q = 0.35 and 0.51 fm-1) were obtained using the MUSL-2A accelerator at the University of Illinois. The photons were detected using a new BaF 2 detector array optimized for ( e,e'1) experiments. For the first time, we succeeded in sensing the vorticity in the nuclear transition currents characterizing collective excitations in doubly closed shell nuclei. This observation was achieved by studying the transverse-longitudinal form factor ratios for the excitations to the 2+ (6.92 MeV) and 3- (6.13 MeV) states of 160. At the same time, we established the relative sign of the two form factors for both transitions. Both relative signs were found to be positive, in agreement with the Siegert limit. We have demonstrated that the transverse-longitudinal form factor ratio in the isospin-forbidden transition to the 1- (7.12 MeV) state has crossed zero at very low momentum transfer. This result lends credence to theoretical speculation of a minimum in the longitudinal form factor resulting from iso spin mixing. However the same results indicate a significant vorticity component in the transition current, which could in principle lead to a destructive interference in the transverse form factor, a possibility which has not been investigated theoretically.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Physics

Year dc:date

2011

Author dc:creator

• Deininger, John R.

Contributors dc:contributor

• Nathan, Alan M.

• nuclear structure
• coincident electron scattering
• nuclear transition currents
• collective excitations

Statement dc:rights

• Copyright 1996 John R. Deininger

Language dc:language

en

Identifier

4014278

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/18842