Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
In-Beam Spectroscopy of Extremely Neutron Deficient Nuclei 110Xe, 163Ta, 169Ir and 172Hg
KTH, School of Engineering Sciences (SCI), Physics.
2009 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

This thesis describes new results obtained from experimental studies of the extremely neutron-deficient isotopes 110Xe, 163Ta, 169Ir, and 172Hg, close to the proton drip-line. The experiments used state-of-the-art equipment for nuclear spectroscopy where a large high resolution Germanium-detector array was coupled to a high-transmission recoil separator.The highly selective recoil-decay tagging technique was applied in order to identify andstudy the most weakly populated reaction channels. The work is based on four experimentsperformed at the Accelerator Laboratory of the University of Jyväskylä, Finland. The experimental techniques used and the experimental set-ups are described. Comparisonbetween experimental results and theoretical predictions are made. The thesis also brieflysummarises the theoretical models employed to interpret the experimental data.

The results for 110Xe indicate an emergence of enhanced collectivity near the N=Z linein the region of the nuclear chart above 100Sn. These findings are interpreted as a possible effect of increased neutron-proton isoscalar pair correlations, a residual interaction effect not accounted for in present-day nuclear models.

The findings for 163Ta reveal three strongly coupled band structures built on differentquasiparticle configurations. The low-lying yrast band exhibits strong signature splittingindicative of a significant triaxial shape asymmetry. An intriguing possibility exits forenhanced octupole correlation in 163Ta, where the odd-proton is proposed to couple to anoctupole-vibrational phonon. However, further investigations are needed to elucidate thisscenario.

Also for 169Ir do the properties of the yrast structure point to a rotational-like behaviourof a moderately deformed nucleus exhibiting a triaxial shape. For neither 163Taor 169Ir do the experimental results fully agree with theoretical predictions for the shapeevolution of the neutron-deficient tantalum and iridium isotopes, approaching the protondrip-line.The nearly constant level spacing in 172Hg between the lowest excited 2+, 4+ and 6+states suggests a transition to a near-spherical harmonic collective vibrational structureas compared with heavier even-even Hg isotopes around the neutron midshell and above.The experimental data have been compared with total Routhian surface calculations and quasiparticle random phase approximation calculations.

Place, publisher, year, edition, pages
Stockholm: KTH , 2009. , x, 57 p.
Series
Trita-FYS, ISSN 0280-316X ; 2009:19
National Category
Physical Sciences
Identifiers
URN: urn:nbn:se:kth:diva-10556ISBN: 978-91-7415-360-6 (print)OAI: oai:DiVA.org:kth-10556DiVA: diva2:219112
Public defence
2009-06-05, Sal FD5, Albanova, Roslagstullsbacken 21, Stockholm, 10:00 (English)
Opponent
Supervisors
Note
QC 20100809Available from: 2009-05-26 Created: 2009-05-26 Last updated: 2010-08-09Bibliographically approved
List of papers
1. First identification of excited states in 169Ir
Open this publication in new window or tab >>First identification of excited states in 169Ir
Show others...
2007 (English)In: Physical Review C. Nuclear Physics, ISSN 0556-2813, E-ISSN 1089-490X, Vol. 75, no 5, 054321- p.Article in journal (Refereed) Published
Abstract [en]

Gamma rays populating the alpha-decaying isomeric state in Ir-169 have been observed for the first time. The experiment employed the recoil-decay tagging method using the JUROGAM gamma-ray spectrometer, the RITU gas-filled recoil separator and the GREAT spectrometer located at the RITU focal plane. The gamma-ray cascade feeding the isomeric alpha-decaying state exhibits a rotational structure consistent with a h(11/2) proton coupled to a triaxially deformed core. The experimental results are compared with predictions from total Routhian surface calculations.

Keyword
collective model description; odd-a nuclei; shape coexistence; neutron-deficient; isotopes; radioactivity; band
National Category
Physical Sciences
Identifiers
urn:nbn:se:kth:diva-7352 (URN)10.1103/PhysRevC.75.054321 (DOI)000246891100031 ()2-s2.0-34547282014 (Scopus ID)
Note
QC 20100809Available from: 2007-06-25 Created: 2007-06-25 Last updated: 2010-08-20Bibliographically approved
2. Indentification of Excited States in the Tz=1 Nucleus 110Xe: Evidence for Enhanced Collectivity Near the N=Z=50 Double Shell Closure
Open this publication in new window or tab >>Indentification of Excited States in the Tz=1 Nucleus 110Xe: Evidence for Enhanced Collectivity Near the N=Z=50 Double Shell Closure
Show others...
2007 (English)In: Physical Review Letters, ISSN 0031-9007, Vol. 99, 022501- p.Article in journal (Refereed) Published
Abstract [en]

Gamma-ray transitions have been identified for the first time in the extremely neutron-deficient (N=Z+2) nucleus Xe110, and the energies of the three lowest excited states in the ground-state band have been deduced. The results establish a breaking of the normal trend of increasing first excited 2+ and 4+ level energies as a function of the decreasing neutron number as the N=50 major shell gap is approached for the neutron-deficient Xe isotopes. This unusual feature is suggested to be an effect of enhanced collectivity, possibly arising from isoscalar n-p interactions becoming increasingly important close to the N=Z line.

Keyword
Excited states; Gamma rays; Ground state; Isotopes; Molecular interactions; Neutrons
National Category
Subatomic Physics
Identifiers
urn:nbn:se:kth:diva-7353 (URN)10.1103/PhysRevLett.99.022501 (DOI)000248021000016 ()2-s2.0-34547188159 (Scopus ID)
Note
QC 20100809Available from: 2007-06-25 Created: 2007-06-25 Last updated: 2010-11-16Bibliographically approved
3. First observation of excited states in Hg-172
Open this publication in new window or tab >>First observation of excited states in Hg-172
Show others...
2009 (English)In: Physical Review C. Nuclear Physics, ISSN 0556-2813, E-ISSN 1089-490X, Vol. 79, no 6, 064315- p.Article in journal (Refereed) Published
Abstract [en]

Excited states in the extremely neutron-deficient isotope Hg-172 have been established for the first time. The Ru-96(Kr-78,2n) reaction was employed to populate excited states in Hg-172 with a cross section sigma approximate to 15 nb. The highly selective recoil-decay tagging (RDT) technique was used to obtain clean in-beam gamma-ray spectra for Hg-172. The yrast ground-state band has tentatively been established up to I=6 h. The data have been interpreted within the framework of total Routhian surface and quasiparticle random phase approximation calculations.

.

 

Keyword
neutron-deficient hg, light mercury isotopes, total data readout, shape, coexistence, nuclei, spectroscopy, transition
National Category
Subatomic Physics
Identifiers
urn:nbn:se:kth:diva-18578 (URN)10.1103/PhysRevC.79.064315 (DOI)000267701200026 ()2-s2.0-67650164848 (Scopus ID)
Note
QC 20100525Available from: 2010-08-05 Created: 2010-08-05 Last updated: 2017-12-12Bibliographically approved
4. (gamma)-ray spectroscopy of 163Ta
Open this publication in new window or tab >>(gamma)-ray spectroscopy of 163Ta
Show others...
2009 (English)In: Physical Review C. Nuclear Physics, ISSN 0556-2813, E-ISSN 1089-490X, Vol. 80, no 5, 054316- p.Article in journal (Refereed) Published
Abstract [en]

Excited states in Ta-163 have been identified for the first time using the Cd-106(Ni-60,3p) fusion evaporation reaction. gamma rays were detected using the JUROGAM gamma-ray spectrometer and recoil discrimination was achieved using the recoil ion transport unit (RITU) gas-filled separator in conjunction with the GREAT spectrometer situated at the focal plane of the RITU. The yrast states are assigned to a strongly coupled rotational band based on a pi h(11/2) configuration. This structure exhibits large signature splitting at low spins that disappears after the paired band crossing because of the alignment of a pair of i(13/2) neutrons. This effect is ascribed to triaxial shape changes induced by the core-polarizing properties of the deformation-aligned h(11/2) proton and the rotation-aligned i(13/2) neutrons. Two additional strongly coupled band structures have been established and are discussed in terms of octupole-vibrational and two-quasiparticle excitations built on the yrast structure. The experimental results are compared with predictions from cranked-shell-model and total-Routhian-surface calculations.

National Category
Subatomic Physics
Identifiers
urn:nbn:se:kth:diva-10555 (URN)10.1103/PhysRevC.80.054316 (DOI)000272313000030 ()2-s2.0-71049180361 (Scopus ID)
Funder
EU, European Research Council, HPRI-CT-1999-00044Swedish Research Council
Note
gamma-ray spectroscopy of Ta-163 QC 20110323Available from: 2009-05-26 Created: 2009-05-26 Last updated: 2011-03-23Bibliographically approved

Open Access in DiVA

fulltext(2708 kB)193 downloads
File information
File name FULLTEXT01.pdfFile size 2708 kBChecksum SHA-512
b9b44c81376afeea0a8df2cef382bef0355ef8197b86b46c45dd0503269cfb025875197dcd52de90bb89a48cdcd43df8d43c26387945da704c957167267653a3
Type fulltextMimetype application/pdf

Search in DiVA

By author/editor
Sandzelius, Mikael
By organisation
Physics
Physical Sciences

Search outside of DiVA

GoogleGoogle Scholar
Total: 193 downloads
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

isbn
urn-nbn

Altmetric score

isbn
urn-nbn
Total: 266 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf