{"id":{"repo_id":"wustl","oai_identifier":"oai:openscholarship.wustl.edu:etd-2348"},"canonical_url":"https://search.dev.ndltd.org/etd/wustl/oai:openscholarship.wustl.edu:etd-2348","repository":{"repo_id":"wustl","name":"Washington University in St. Louis","base_url":"https://openscholarship.wustl.edu/do/oai/"},"display":{"title":"Shape and Structure of Neutron-Rich from Cf-252 Fission Fragments","abstract":"

The transition quadrupole moments, Qt, of rotational bands in the neutron-rich, even-mass 102-108Mo and 108-112Ru nuclei were measured with the Doppler-shift attenuation method. The nuclei were populated as fission fragments from 252Cf fission. The detector setup consisted of the Gammasphere spectrometer and the Hercules fast-plastic array. This allowed the measurement of asymmetric DSAM lineshapes at different Gammasphere detector angles with respect to the fission axis. The measurements typically covered the 6 to 16ћ spin range of the ground-state band and at least a strong transition in the γ band. At moderate spin, the Qt moments are found to be reduced with respect to the values near the ground states, the latter being reported in the literature.

An attempt has been made (by Afanasjev) to describe the data in the framework of cranked relativistic Hartree-Bogolyubov theory, and the results are reported in the present work as well as in a Physics Letters paper by Snyder et al. For 104Mo reliable predictions can be made. Here an oblate shape and a low-spin triaxial shape (deformation parameter γ~-44°), predicted to be favored in other theoretical calculations, are ruled out by the data. There is some indication for a gradual change, at higher spin, from an initially prolate shape to a triaxial shape in 104Mo. The Qt data for 106Mo and 110,112Ru support this picture. The challenge of theory to describe the Qt data is addressed, which has to do with the very γ-soft potential-energy surfaces.

As a byproduct of the Qt analysis (which requires the determination of the intensities of the feeding transitions), the transition intensities of many weak high-spin or non-yrast states have been determined. These previously unknown intensity data are also reported.

In the appendix, the results of an attenuation-coefficient analysis for γ-ray angular distributions (due to recoil-in-vacuum) in heavy Ba isotopes are reported. These results are from a separate project, though from the same data set.

","abstract_html":"<p>The transition quadrupole moments, Q<sub>t</sub>, of rotational bands in the neutron-rich, even-mass <super>102-108</super>Mo and <super>108-112</super>Ru nuclei were measured with the Doppler-shift attenuation method. The nuclei were populated as fission fragments from <super>252</super>Cf fission. The detector setup consisted of the Gammasphere spectrometer and the Hercules fast-plastic array. This allowed the measurement of asymmetric DSAM lineshapes at different Gammasphere detector angles with respect to the fission axis. The measurements typically covered the 6 to 16&#1115; spin range of the ground-state band and at least a strong transition in the &#947; band. At moderate spin, the Q<sub>t</sub> moments are found to be reduced with respect to the values near the ground states, the latter being reported in the literature.</p><p>An attempt has been made (by Afanasjev) to describe the data in the framework of cranked relativistic Hartree-Bogolyubov theory, and the results are reported in the present work as well as in a Physics Letters paper by Snyder et al. For <super>104</super>Mo reliable predictions can be made. Here an oblate shape and a low-spin triaxial shape (deformation parameter &#947;~-44°), predicted to be favored in other theoretical calculations, are ruled out by the data. There is some indication for a gradual change, at higher spin, from an initially prolate shape to a triaxial shape in <super>104</super>Mo. The Q<sub>t</sub> data for <super>106</super>Mo and <super>110,112</super>Ru support this picture. The challenge of theory to describe the Q<sub>t</sub> data is addressed, which has to do with the very &#947;-soft potential-energy surfaces.</p><p>As a byproduct of the Q<sub>t</sub> analysis (which requires the determination of the intensities of the feeding transitions), the transition intensities of many weak high-spin or non-yrast states have been determined. These previously unknown intensity data are also reported.</p><p>In the appendix, the results of an attenuation-coefficient analysis for &#947;-ray angular distributions (due to recoil-in-vacuum) in heavy Ba isotopes are reported. These results are from a separate project, though from the same data set.</p>","abstract_has_math":false,"creators":["Snyder, Jason Benjamin"],"institution":null,"degree_name":"Doctor of Philosophy (PhD)","degree_level":"Dissertation","degree_discipline":"Physics","degree_department":null,"school":null,"contributors":["Demetrios G Sarantites"],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2014,"date_issued":"2014-09-01T07:00:00Z","date_published":"2014-09-01T07:00:00Z","updated_at":"2026-07-24T06:12:48Z","subjects":["cranked relativistic Hartree-Bogoliubov Theory","excited state lifetimes","fission fragments","rotational bands","transition quadrupole moments","triaxiality"],"languages":["English (en)"],"rights":[],"rights_urls":[],"identifier_entries":[{"key":"dc:identifier.doi","label":"DOI","values":["https://doi.org/10.7936/K7CV4FVC"],"render_values":[{"text":"https://doi.org/10.7936/K7CV4FVC","href":"https://doi.org/10.7936/K7CV4FVC","code":true}]}]},"links":{"outbound_url":"https://openscholarship.wustl.edu/etd/1348","outbound_label":"Repository record","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Demetrios G Sarantites"]},{"key":"dc:creator","label":"Author","values":["Snyder, Jason Benjamin"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date.available","label":"Dc Date Available","values":["2014-10-08T07:00:00Z"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Physics"]},{"key":"thesis:degree_level","label":"Degree Level","values":["Dissertation"]},{"key":"thesis:degree_name","label":"Degree Name","values":["Doctor of Philosophy (PhD)"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["cranked relativistic Hartree-Bogoliubov Theory","excited state lifetimes","fission fragments","rotational bands","transition quadrupole moments","triaxiality"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language","label":"Dc Language","values":["English (en)"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["https://openscholarship.wustl.edu/etd/1348"]},{"key":"dc:identifier.doi","label":"DOI","values":["https://doi.org/10.7936/K7CV4FVC"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["

The transition quadrupole moments, Qt, of rotational bands in the neutron-rich, even-mass 102-108Mo and 108-112Ru nuclei were measured with the Doppler-shift attenuation method. The nuclei were populated as fission fragments from 252Cf fission. The detector setup consisted of the Gammasphere spectrometer and the Hercules fast-plastic array. This allowed the measurement of asymmetric DSAM lineshapes at different Gammasphere detector angles with respect to the fission axis. The measurements typically covered the 6 to 16ћ spin range of the ground-state band and at least a strong transition in the γ band. At moderate spin, the Qt moments are found to be reduced with respect to the values near the ground states, the latter being reported in the literature.

An attempt has been made (by Afanasjev) to describe the data in the framework of cranked relativistic Hartree-Bogolyubov theory, and the results are reported in the present work as well as in a Physics Letters paper by Snyder et al. For 104Mo reliable predictions can be made. Here an oblate shape and a low-spin triaxial shape (deformation parameter γ~-44°), predicted to be favored in other theoretical calculations, are ruled out by the data. There is some indication for a gradual change, at higher spin, from an initially prolate shape to a triaxial shape in 104Mo. The Qt data for 106Mo and 110,112Ru support this picture. The challenge of theory to describe the Qt data is addressed, which has to do with the very γ-soft potential-energy surfaces.

As a byproduct of the Qt analysis (which requires the determination of the intensities of the feeding transitions), the transition intensities of many weak high-spin or non-yrast states have been determined. These previously unknown intensity data are also reported.

In the appendix, the results of an attenuation-coefficient analysis for γ-ray angular distributions (due to recoil-in-vacuum) in heavy Ba isotopes are reported. These results are from a separate project, though from the same data set.

"]},{"key":"dc:title","label":"Title","values":["Shape and Structure of Neutron-Rich from Cf-252 Fission Fragments"]}]}],"canonical_facts":{"dc:contributor":["Demetrios G Sarantites"],"dc:creator":["Snyder, Jason Benjamin"],"dc:date.available":["2014-10-08T07:00:00Z"],"dc:description.abstract":["

The transition quadrupole moments, Qt, of rotational bands in the neutron-rich, even-mass 102-108Mo and 108-112Ru nuclei were measured with the Doppler-shift attenuation method. The nuclei were populated as fission fragments from 252Cf fission. The detector setup consisted of the Gammasphere spectrometer and the Hercules fast-plastic array. This allowed the measurement of asymmetric DSAM lineshapes at different Gammasphere detector angles with respect to the fission axis. The measurements typically covered the 6 to 16ћ spin range of the ground-state band and at least a strong transition in the γ band. At moderate spin, the Qt moments are found to be reduced with respect to the values near the ground states, the latter being reported in the literature.

An attempt has been made (by Afanasjev) to describe the data in the framework of cranked relativistic Hartree-Bogolyubov theory, and the results are reported in the present work as well as in a Physics Letters paper by Snyder et al. For 104Mo reliable predictions can be made. Here an oblate shape and a low-spin triaxial shape (deformation parameter γ~-44°), predicted to be favored in other theoretical calculations, are ruled out by the data. There is some indication for a gradual change, at higher spin, from an initially prolate shape to a triaxial shape in 104Mo. The Qt data for 106Mo and 110,112Ru support this picture. The challenge of theory to describe the Qt data is addressed, which has to do with the very γ-soft potential-energy surfaces.

As a byproduct of the Qt analysis (which requires the determination of the intensities of the feeding transitions), the transition intensities of many weak high-spin or non-yrast states have been determined. These previously unknown intensity data are also reported.

In the appendix, the results of an attenuation-coefficient analysis for γ-ray angular distributions (due to recoil-in-vacuum) in heavy Ba isotopes are reported. These results are from a separate project, though from the same data set.

"],"dc:identifier":["https://openscholarship.wustl.edu/etd/1348"],"dc:identifier.doi":["https://doi.org/10.7936/K7CV4FVC"],"dc:language":["English (en)"],"dc:subject":["cranked relativistic Hartree-Bogoliubov Theory","excited state lifetimes","fission fragments","rotational bands","transition quadrupole moments","triaxiality"],"dc:title":["Shape and Structure of Neutron-Rich from Cf-252 Fission Fragments"],"thesis:degree_discipline":["Physics"],"thesis:degree_level":["Dissertation"],"thesis:degree_name":["Doctor of Philosophy (PhD)"]},"updated_at":"2026-07-24T06:12:48Z"}