skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: First observation of excited states in the {sup 138}I nucleus

Abstract

Excited states in the {sup 138}I nucleus, including T{sub 1/2}=1.3 {mu}s isomer decaying by a stretched E2 transition of 68 keV, were observed for the first time. The {sup 138}I nucleus was populated in the spontaneous fission of {sup 248}Cm and studied by means of prompt {gamma}-ray spectroscopy using the EUROGAM 2 array. The microsecond isomer was populated in the neutron-induced fission of {sup 235}U and observed at the LOHENGRIN separator. Excitation scheme consists of a low-spin part and a medium-spin, {delta}I=1, band based on the 7{sup -} state with the ({pi}g{sub 7/2}{nu}f{sub 7/2}){sub 7{sup -}} dominating configuration, as predicted by the shell model. The shell-model calculations of {sup 138}I provide the optimum reproduction of the experimental scheme when the {pi}d{sub 5/2} orbital is lowered by 600 keV relative to its position in {sup 133}Sb. In the calculation the isomeric level has spin and parity 3{sup -} and deexcites by an E2 isomeric transition to the 1{sup -} level, located only 9 keV above the predicted 0{sup -} ground state. Considering additional information on the ground-state spin from the literature, we propose that in {sup 138}I the 1{sup -} level corresponds to the ground state and the 0{sup -} ismore » located above. We note, however, that additional measurements are required to resolve this problem.« less

Authors:
; ; ;  [1]; ; ;  [2];  [3];  [4]; ; ;  [5];  [5];  [6]; ;  [7];  [8]
  1. Faculty of Physics, Warsaw University, ul.Hoza 69, 00-681 Warsaw (Poland)
  2. Laboratoire de Physique Subatomique et de Cosmologie, IN2P3-Centre National de la Recherche Scientifique/Universite Joseph Fourier, F-38026 Grenoble Cedex (France)
  3. Saha Institute of Nuclear Physics, 1/AF Bidhan Nagar, Kolkata 700064 (India)
  4. Department of Physics, Bengal Engineering and Science University, Shibpur, Howrah 711103 (India)
  5. Institut Laue-Langevin, B.P. 156, F-38042 Grenoble Cedex 9 (France)
  6. (United Kingdom)
  7. Department of Physics and Astronomy, University of Manchester, Manchester M13 9PL (United Kingdom)
  8. Argonne National Laboratory, Argonne, Illinois 60439 (United States)
Publication Date:
OSTI Identifier:
20995281
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physical Review. C, Nuclear Physics; Journal Volume: 75; Journal Issue: 5; Other Information: DOI: 10.1103/PhysRevC.75.054319; (c) 2007 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
73 NUCLEAR PHYSICS AND RADIATION PHYSICS; ANTIMONY 133; CURIUM 248; E2-TRANSITIONS; EXCITATION; EXCITED STATES; GAMMA SPECTROSCOPY; GROUND STATES; IODINE 138; ISOMERIC TRANSITIONS; ISOMERS; KEV RANGE; NEUTRONS; PARITY; SHELL MODELS; SPIN; SPONTANEOUS FISSION; URANIUM 235

Citation Formats

RzaPca-Urban, T., PaPgowska, K., Urban, W., Zlomaniec, A., Genevey, J., Pinston, J. A., Simpson, G. S., Saha Sarkar, M., Sarkar, S., Faust, H., Scherillo, A., Tsekhanovich, I., Orlandi, R., Department of Physics and Astronomy, University of Manchester, Manchester M13 9PL, Durell, J. L., Smith, A. G., and Ahmand, I. First observation of excited states in the {sup 138}I nucleus. United States: N. p., 2007. Web. doi:10.1103/PHYSREVC.75.054319.
RzaPca-Urban, T., PaPgowska, K., Urban, W., Zlomaniec, A., Genevey, J., Pinston, J. A., Simpson, G. S., Saha Sarkar, M., Sarkar, S., Faust, H., Scherillo, A., Tsekhanovich, I., Orlandi, R., Department of Physics and Astronomy, University of Manchester, Manchester M13 9PL, Durell, J. L., Smith, A. G., & Ahmand, I. First observation of excited states in the {sup 138}I nucleus. United States. doi:10.1103/PHYSREVC.75.054319.
RzaPca-Urban, T., PaPgowska, K., Urban, W., Zlomaniec, A., Genevey, J., Pinston, J. A., Simpson, G. S., Saha Sarkar, M., Sarkar, S., Faust, H., Scherillo, A., Tsekhanovich, I., Orlandi, R., Department of Physics and Astronomy, University of Manchester, Manchester M13 9PL, Durell, J. L., Smith, A. G., and Ahmand, I. Tue . "First observation of excited states in the {sup 138}I nucleus". United States. doi:10.1103/PHYSREVC.75.054319.
@article{osti_20995281,
title = {First observation of excited states in the {sup 138}I nucleus},
author = {RzaPca-Urban, T. and PaPgowska, K. and Urban, W. and Zlomaniec, A. and Genevey, J. and Pinston, J. A. and Simpson, G. S. and Saha Sarkar, M. and Sarkar, S. and Faust, H. and Scherillo, A. and Tsekhanovich, I. and Orlandi, R. and Department of Physics and Astronomy, University of Manchester, Manchester M13 9PL and Durell, J. L. and Smith, A. G. and Ahmand, I.},
abstractNote = {Excited states in the {sup 138}I nucleus, including T{sub 1/2}=1.3 {mu}s isomer decaying by a stretched E2 transition of 68 keV, were observed for the first time. The {sup 138}I nucleus was populated in the spontaneous fission of {sup 248}Cm and studied by means of prompt {gamma}-ray spectroscopy using the EUROGAM 2 array. The microsecond isomer was populated in the neutron-induced fission of {sup 235}U and observed at the LOHENGRIN separator. Excitation scheme consists of a low-spin part and a medium-spin, {delta}I=1, band based on the 7{sup -} state with the ({pi}g{sub 7/2}{nu}f{sub 7/2}){sub 7{sup -}} dominating configuration, as predicted by the shell model. The shell-model calculations of {sup 138}I provide the optimum reproduction of the experimental scheme when the {pi}d{sub 5/2} orbital is lowered by 600 keV relative to its position in {sup 133}Sb. In the calculation the isomeric level has spin and parity 3{sup -} and deexcites by an E2 isomeric transition to the 1{sup -} level, located only 9 keV above the predicted 0{sup -} ground state. Considering additional information on the ground-state spin from the literature, we propose that in {sup 138}I the 1{sup -} level corresponds to the ground state and the 0{sup -} is located above. We note, however, that additional measurements are required to resolve this problem.},
doi = {10.1103/PHYSREVC.75.054319},
journal = {Physical Review. C, Nuclear Physics},
number = 5,
volume = 75,
place = {United States},
year = {Tue May 15 00:00:00 EDT 2007},
month = {Tue May 15 00:00:00 EDT 2007}
}
  • Excited states in the {sup 138}I nucleus, including T{sub 1/2}=1.3 {micro}s isomer decaying by a stretched E2 transition of 68 keV, were observed for the first time. The {sup 138}I nucleus was populated in the spontaneous fission of {sup 248}Cm and studied by means of prompt {gamma}-ray spectroscopy using the EUROGAM 2 array. The microsecond isomer was populated in the neutron-induced fission of {sup 235}U and observed at the LOHENGRIN separator. Excitation scheme consists of a low-spin part and a medium-spin, {Delta}I=1, band based on the 7{sup -} state with the ({pi}g{sub 7/2}{nu}{sub 7/2}{sup f}){sub 7{sup -}} dominating configuration, asmore » predicted by the shell model. The shell-model calculations of {sup 138}I provide the optimum reproduction of the experimental scheme when the {pi}{sub 5/2}{sup d} orbital is lowered by 600 keV relative to its position in {sup 133}Sb. In the calculation the isomeric level has spin and parity 3{sup -} and deexcites by an E2 isomeric transition to the 1{sup -} level, located only 9 keV above the predicted 0{sup -} ground state. Considering additional information on the ground-state spin from the literature, we propose that in {sup 138}I the 1{sup -} level corresponds to the ground state and the 0{sup -} is located above. We note, however, that additional measurements are required to resolve this problem.« less
  • Medium-spin, yrast excitations in the {sup 138}Cs nucleus, populated in the spontaneous fission of {sup 248}Cm, were observed for the first time. {sup 138}Cs was studied by means of prompt {gamma}-ray spectroscopy using the EUROGAM2 array. The newly observed yrast cascade, built on the known 6- isomer at 80 keV, was successfully described by shell model calculations. Analogously to the {sup 136}I isotone, the 6- isomer in {sup 138}Cs has the ({pi} g{sub 7/2}{sup 4} d{sub 5/2}{nu} f{sub 7/2}){sub 6-} dominating configuration and the 7{sup -} excitation, located 175 keV above, corresponds to the ({pi} g{sub 7/2}{sup 3} d{sup 2}{submore » 5/2}{nu} f{sub 7/2}){sub 7-} as dominating configuration. Similarly as in {sup 136}I, changing the position of the d{sub 5/2} proton orbital improves the reproduction of the data. However, in {sup 138}Cs the energy of this orbital should be increased compared to its energy in {sup 133}Sb, to get the best description, in contrast to {sup 136}I and {sup 135}Sb, where it had to be decreased. The best reproduction of excitation energies in {sup 138}Cs is obtained assuming that the {pi}d{sub 5/2} orbital in {sup 138}Cs is located about 100 keV higher than in {sup 133}Sb. These observations suggest that the lowering of the d{sub 5/2} s.p. energy in {sup 135}Sb is not a physical effect due to the appearance of a neutron skin, as proposed by other authors, but rather an artifact due to some deficiency of the input data used in the shell model calculations in the region of the doubly magic {sup 132}Sn core.« less
  • The g factor of the 15/2{sup -} state in {sup 137}Xe was measured for the first time by using a newly developed technique for measuring angular correlations with Gammasphere. Spins and parities were assigned to several levels in the N=83 isotones {sup 135}Te, {sup 136}I, {sup 137}Xe, and {sup 138}Cs. The calculated g factor in the shell-model frame is in good agreement with the measured one in the present work. Shell-model calculations also support our spin-parity assignments.
  • Gamma decays depopulating excited states in the odd-odd N=Z - 2 nucleus 48Mn have been observed for the first time. The yrast band has been built up from the 4+ ground state to 13+, just shy of the expected band termination at 15+. When compared with its mirror, 48V, the Coulomb energy differences are unlike any other previously measured which, until now, have been dominated by a sudden rotational alignment. Such an alignment is expected to be blocked in these odd-odd nuclei and calculations not only confirm this, but also infer that any Coulomb difference is mostly due to monopolemore » effects.« less