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Title: Nuclear shape and structure in neutron-rich 110,111Tc

Abstract

The structure of Tc nuclei is extended to the moreneutron-rich regions based on measurements of prompt gamma rays from thespontaneous fission of 252Cf at Gammasphere. The level scheme of N=67neutron-rich (Z=43) 110Tc is established for the first time and that of111Tc is expanded. The ground-state band of 111Tc reaches theband-crossing region and the new observation of the weakly populatedalpha = -1/2 member of the band provides important information ofsignature splitting. The systematics of band crossings in the isotopicand isotonic chains and a CSM calculation suggest that the band crossingof the gs band of 111Tc is due to alignment of a pair of h11/2 neutrons.The best fit to signature splitting, branching ratios, and excitations ofthe ground-state band of 111Tc by RTRP model calculations result in ashape of epsilon2 = 0.32 and gamma = -26 deg. for this nucleus. Itstriaxiality is larger than that of 107Tc, to indicate increasingtriaxiality with increasing neutron number. The identification of theweakly-populated "K+2 satellite" band provides strong evidence for thelarge triaxiality of 111Tc. In 110Tc the four lowest-lying levelsobserved are very similar to those in 108Tc. At an excitation of 478.9keV above the lowest state observed, ten states of a delta I = 1 band areobserved. Thismore » band is very analogous to the delta I = 1 bands in106,108Tc, but it has greater signature splitting at higherspins.« less

Authors:
; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ;
Publication Date:
Research Org.:
Ernest Orlando Lawrence Berkeley NationalLaboratory, Berkeley, CA (US)
Sponsoring Org.:
USDOE Director. Office of Science. Office of AdvancedScientific Computing Research. Office of Nuclear Physics,DE-FG05-88ER40407, DE-AC02-05CH11231, DE-AC-99ID13727, W-7405-ENG48; Major State Basic Research Development Program G2000077400; ChineseNational Natural Science Foundation 10375032
OSTI Identifier:
901674
Report Number(s):
LBNL-59476
R&D Project: NOXRAS; BnR: KB0401024; TRN: US0702655
DOE Contract Number:
DE-AC02-05CH11231
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physical Review C; Journal Volume: 74; Related Information: Journal Publication Date: 2006
Country of Publication:
United States
Language:
English
Subject:
73; 71; ALIGNMENT; BRANCHING RATIO; CHAINS; ENERGY LEVELS; EXCITATION; NEUTRONS; NUCLEI; SHAPE; SPONTANEOUS FISSION; Fission Gamma Spectroscopy Triaxial Rotational Bands

Citation Formats

Luo, Y.X., Hamilton, J.H., Rasmussen, J.O., Ramayya, A.V., Stefanescu, I., Hwang, J.K., Zhu, S.J., Gore, P.M., Jones, E.F., Fong,D., Wu, S.C., Lee, I.Y., Ginter, T.N., Ter-Akopian, G.M., Daniel, A.V., Stoyer, M.A., Donangelo, R., and Gelberg, A.. Nuclear shape and structure in neutron-rich 110,111Tc. United States: N. p., 2006. Web. doi:10.1103/PhysRevC.74.024308.
Luo, Y.X., Hamilton, J.H., Rasmussen, J.O., Ramayya, A.V., Stefanescu, I., Hwang, J.K., Zhu, S.J., Gore, P.M., Jones, E.F., Fong,D., Wu, S.C., Lee, I.Y., Ginter, T.N., Ter-Akopian, G.M., Daniel, A.V., Stoyer, M.A., Donangelo, R., & Gelberg, A.. Nuclear shape and structure in neutron-rich 110,111Tc. United States. doi:10.1103/PhysRevC.74.024308.
Luo, Y.X., Hamilton, J.H., Rasmussen, J.O., Ramayya, A.V., Stefanescu, I., Hwang, J.K., Zhu, S.J., Gore, P.M., Jones, E.F., Fong,D., Wu, S.C., Lee, I.Y., Ginter, T.N., Ter-Akopian, G.M., Daniel, A.V., Stoyer, M.A., Donangelo, R., and Gelberg, A.. Thu . "Nuclear shape and structure in neutron-rich 110,111Tc". United States. doi:10.1103/PhysRevC.74.024308. https://www.osti.gov/servlets/purl/901674.
@article{osti_901674,
title = {Nuclear shape and structure in neutron-rich 110,111Tc},
author = {Luo, Y.X. and Hamilton, J.H. and Rasmussen, J.O. and Ramayya, A.V. and Stefanescu, I. and Hwang, J.K. and Zhu, S.J. and Gore, P.M. and Jones, E.F. and Fong,D. and Wu, S.C. and Lee, I.Y. and Ginter, T.N. and Ter-Akopian, G.M. and Daniel, A.V. and Stoyer, M.A. and Donangelo, R. and Gelberg, A.},
abstractNote = {The structure of Tc nuclei is extended to the moreneutron-rich regions based on measurements of prompt gamma rays from thespontaneous fission of 252Cf at Gammasphere. The level scheme of N=67neutron-rich (Z=43) 110Tc is established for the first time and that of111Tc is expanded. The ground-state band of 111Tc reaches theband-crossing region and the new observation of the weakly populatedalpha = -1/2 member of the band provides important information ofsignature splitting. The systematics of band crossings in the isotopicand isotonic chains and a CSM calculation suggest that the band crossingof the gs band of 111Tc is due to alignment of a pair of h11/2 neutrons.The best fit to signature splitting, branching ratios, and excitations ofthe ground-state band of 111Tc by RTRP model calculations result in ashape of epsilon2 = 0.32 and gamma = -26 deg. for this nucleus. Itstriaxiality is larger than that of 107Tc, to indicate increasingtriaxiality with increasing neutron number. The identification of theweakly-populated "K+2 satellite" band provides strong evidence for thelarge triaxiality of 111Tc. In 110Tc the four lowest-lying levelsobserved are very similar to those in 108Tc. At an excitation of 478.9keV above the lowest state observed, ten states of a delta I = 1 band areobserved. This band is very analogous to the delta I = 1 bands in106,108Tc, but it has greater signature splitting at higherspins.},
doi = {10.1103/PhysRevC.74.024308},
journal = {Physical Review C},
number = ,
volume = 74,
place = {United States},
year = {Thu Feb 02 00:00:00 EST 2006},
month = {Thu Feb 02 00:00:00 EST 2006}
}
  • The high-spin nuclear structure of Tc isotopes is extended to more neutron-rich regions based on the measurements of prompt {gamma} rays from the spontaneous fission of {sup 252}Cf at the Gammasphere. The high-spin level scheme of N=67 neutron-rich {sup 110}Tc (Z=43) is established for the first time, and that of {sup 111}Tc is extended and expanded. The ground band of {sup 111}Tc reaches the band-crossing region, and the new observation of the weakly populated {alpha}=-1/2 member of the band provides important information on signature splitting. The systematics of band crossings in the isotopic and isotonic chains and a CSM calculationmore » suggest that the band crossing of the ground band of {sup 111}Tc is due to alignment of a pair of h{sub 11/2} neutrons. The best fit to signature splitting, branching ratios, and excitations of the ground band of {sup 111}Tc by the rigid triaxial rotor plus particle model calculations result in a shape of {epsilon}{sub 2}=0.32 and {gamma}=-26 deg. for this nucleus. Its triaxiality is larger than that of {sup 107,109}Tc, which indicates increasing triaxiality in Tc isotopes with increasing neutron number. The identification of the weakly populated K+2 satellite band provides strong evidence for the large triaxiality of {sup 111}Tc. In {sup 110}Tc, the four lowest-lying levels observed are very similar to those in {sup 108}Tc. At an excitation of 478.9 keV above the lowest state observed, ten states of a {delta}I=1 band are observed. This band of {sup 110}Tc is very analogous to the {delta}I=1 bands in {sup 106,108}Tc, but it has greater and reversal signature splitting at higher spins.« less
  • The neutron-deficient and neutron-rich zirconium nuclei are studied using statistical theory. The deformation dependence of occupation numbers of the neutron orbitals in these nuclei near the Fermi level is investigated. The preference of the neutrons to occupy or vacate a particular orbital is found to contribute a particular shape to the nucleus. {copyright} {ital 1997} {ital The American Physical Society}
  • The shell structure underlying shape changes in neutron-rich nuclei near N=28 has been investigated by a novel application of the transient-field technique to measure the first-excited-state g factors in {sup 38}S and {sup 40}S produced as fast radioactive beams. There is a fine balance between proton and neutron contributions to the magnetic moments in both nuclei. The g factor of deformed {sup 40}S does not resemble that of a conventional collective nucleus because spin contributions are more important than usual.
  • B(E2;2{sub 1}{sup +}{yields}0{sub 1}{sup +}) values have been measured for the unstable nuclei {sup 88}Kr (N = 52) and {sup 92}Kr (N = 56) using projectile Coulomb excitation at ISOLDE, CERN. With this experiment the local maximum in E(2{sub 1}{sup +}) in {sup 92}Kr and the role of the N = 56 subshell closure can be studied.
  • The effect of projectile shape on cross sections and momentum distributions of fragments from heavy ion reactions is studied. We propose a new approach that implements the underlying symmetries of each isotope with a few parameters directly in the density. Various densities and their nuclear structure are analyzed in the reactions of {sup 12}C and {sup 11}Li, {sup 11}Be, and {sup 11}C on a carbon target. {copyright} {ital 1996 The American Physical Society.}