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Title: Rotational structures and their evolution with spin in {sup 152}Gd.

Abstract

The fusion-evaporation reaction involving a 175 MeV {sup 36}S beam and a {sup 124}Sn target was performed, and the emitted {gamma} rays were observed with the Gammasphere spectrometer. Significant additions to the level scheme of {sup 152}Gd were made in spite of the relative weakness of the {alpha}4n exit channel, being only {approx}2% of the total fusion cross-section. The high-spin behavior of {sup 152}Gd was compared with that of other N=88 nuclei. A striking similarity was observed with {sup 154}Dy and it is therefore suggested that the angular-momentum-induced shape changes that take place in {sup 154}Dy also occur in {sup 152}Gd in the 30--40{h_bar} spin range. This is supported by Cranked Nilsson-Strutinsky calculations which were used to interpret the high-spin bands. It is found that a better agreement between calculation and experiment is obtained if the Z=64 shell gap increases with a decreasing number of valence particles outside the doubly-closed {sub 64}{sup 146}Gd82 nucleus.

Authors:
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Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org.:
USDOE Office of Science (SC); NSF-Florida; UK Engineering and Physical Science Research Council; Swedish Science Research Council
OSTI Identifier:
914961
Report Number(s):
ANL/PHY/JA-58683
Journal ID: ISSN 0556-2813; PRVCAN; TRN: US200817%%36
DOE Contract Number:
DE-AC02-06CH11357
Resource Type:
Journal Article
Resource Relation:
Journal Name: Phys. Rev. C; Journal Volume: 75; Journal Issue: 2007
Country of Publication:
United States
Language:
ENGLISH
Subject:
73 NUCLEAR PHYSICS AND RADIATION PHYSICS; MEV RANGE 100-1000; SPIN; DYSPROSIUM 154; GADOLINIUM 152; TIN 124 TARGET; SULFUR 36 REACTIONS; GAMMA RADIATION; HIGH SPIN STATES

Citation Formats

Campbell, D. B., Laird, R. W., Riley, M. A., Simpson, J., Kondev, F. G., Hartley, D. J., Janssens, R. V. F., Brown, T. B., Carpenter, M. P., Fallon, P., Fischer, S. M., Lauritsen, T., Nisius, D., Ragnarsson, I., LLNL, Texas Lutheran Univ., Florida State Univ., Daresbury Lab., U.S. Naval Academy, SRL, LBNL., DePaul Univ., and Lund Univ.. Rotational structures and their evolution with spin in {sup 152}Gd.. United States: N. p., 2007. Web. doi:10.1103/PhysRevC.75.064314.
Campbell, D. B., Laird, R. W., Riley, M. A., Simpson, J., Kondev, F. G., Hartley, D. J., Janssens, R. V. F., Brown, T. B., Carpenter, M. P., Fallon, P., Fischer, S. M., Lauritsen, T., Nisius, D., Ragnarsson, I., LLNL, Texas Lutheran Univ., Florida State Univ., Daresbury Lab., U.S. Naval Academy, SRL, LBNL., DePaul Univ., & Lund Univ.. Rotational structures and their evolution with spin in {sup 152}Gd.. United States. doi:10.1103/PhysRevC.75.064314.
Campbell, D. B., Laird, R. W., Riley, M. A., Simpson, J., Kondev, F. G., Hartley, D. J., Janssens, R. V. F., Brown, T. B., Carpenter, M. P., Fallon, P., Fischer, S. M., Lauritsen, T., Nisius, D., Ragnarsson, I., LLNL, Texas Lutheran Univ., Florida State Univ., Daresbury Lab., U.S. Naval Academy, SRL, LBNL., DePaul Univ., and Lund Univ.. Mon . "Rotational structures and their evolution with spin in {sup 152}Gd.". United States. doi:10.1103/PhysRevC.75.064314.
@article{osti_914961,
title = {Rotational structures and their evolution with spin in {sup 152}Gd.},
author = {Campbell, D. B. and Laird, R. W. and Riley, M. A. and Simpson, J. and Kondev, F. G. and Hartley, D. J. and Janssens, R. V. F. and Brown, T. B. and Carpenter, M. P. and Fallon, P. and Fischer, S. M. and Lauritsen, T. and Nisius, D. and Ragnarsson, I. and LLNL and Texas Lutheran Univ. and Florida State Univ. and Daresbury Lab. and U.S. Naval Academy and SRL and LBNL. and DePaul Univ. and Lund Univ.},
abstractNote = {The fusion-evaporation reaction involving a 175 MeV {sup 36}S beam and a {sup 124}Sn target was performed, and the emitted {gamma} rays were observed with the Gammasphere spectrometer. Significant additions to the level scheme of {sup 152}Gd were made in spite of the relative weakness of the {alpha}4n exit channel, being only {approx}2% of the total fusion cross-section. The high-spin behavior of {sup 152}Gd was compared with that of other N=88 nuclei. A striking similarity was observed with {sup 154}Dy and it is therefore suggested that the angular-momentum-induced shape changes that take place in {sup 154}Dy also occur in {sup 152}Gd in the 30--40{h_bar} spin range. This is supported by Cranked Nilsson-Strutinsky calculations which were used to interpret the high-spin bands. It is found that a better agreement between calculation and experiment is obtained if the Z=64 shell gap increases with a decreasing number of valence particles outside the doubly-closed {sub 64}{sup 146}Gd82 nucleus.},
doi = {10.1103/PhysRevC.75.064314},
journal = {Phys. Rev. C},
number = 2007,
volume = 75,
place = {United States},
year = {Mon Jan 01 00:00:00 EST 2007},
month = {Mon Jan 01 00:00:00 EST 2007}
}
  • The fusion-evaporation reaction involving a 175 MeV {sup 36}S beam and a {sup 124}Sn target was performed, and the emitted {gamma} rays were observed with the Gammasphere spectrometer. Significant additions to the level scheme of {sup 152}Gd were made in spite of the relative weakness of the {alpha}4n exit channel, being only {approx}2% of the total fusion cross-section. The high-spin behavior of {sup 152}Gd was compared with that of other N=88 nuclei. A striking similarity was observed with {sup 154}Dy and it is therefore suggested that the angular-momentum-induced shape changes that take place in {sup 154}Dy also occur in {supmore » 152}Gd in the 30-40h spin range. This is supported by Cranked Nilsson-Strutinsky calculations which were used to interpret the high-spin bands. It is found that a better agreement between calculation and experiment is obtained if the Z=64 shell gap increases with a decreasing number of valence particles outside the doubly-closed {sub 64}{sup 146}Gd{sub 82} nucleus.« less
  • Angular-correlation methods were used to establish the spin sequence and the multipele mixing ratio of several gamma -ray cascades in the decay of Eu/sup 152/ Eu/sup 152//sup m/ Eu/sup 1/ s/sup 54/, and to measure the nuclear g-factor of Sm/sup 152/. For liquid sources, only the 123 kev level of Gd/sup 154/ showed attenuation. lt was found that each level in the decay of Eu/sup 152/ to Sm/sup 152/ cor responds to a level of the same spin and parity in the decay of Eu/sup 164/ to Gd/sup 154/. In Gd/sup 154/ an additional 2< s->s level of 1721 kevmore » exists, which decays by E1 radiation to the 2/sup +/, K = 2 and the 2/sup +/, K = 0 levels. The measurements of the 1290 to 344 and 1100 to 344 kev cascades in Gd/ sup 152/ were consistent with a tentative spin assianment of 2 or 3 to the (1634 plus or minus 25) kev level and of 4 to the 1444 kev level. The g-factor of the first notatioual state of Sm/sup 152/ was measured using liquid and polycrystalline sources. Assuming the internal field of the paramagnetic electron shell to be proportional to T/sup -1/, the experimentally observed values g/sub eff/= 0.38 plus or minus 0.06 at 300 deg K and g/sub eff/ = 0.180 plus or minus 0.065 at 1200 deg K yield a g-factor g/sub N/ = 0.115 plus or minus 0.075. (auth)« less
  • The spin of the lowest level observed in the superdeformed band in {sup 152}Dy is determined to be {ital I}{sub 0}=25 rather than the previously assigned {ital I}{sub 0}=22. As a result, we have {ital scrI}{sup (1)}{gt}{ital scrI}{sup (2)} and both {ital scrI}{sup (1)} and {ital scrI}{sup (2)} decrease very slowly with rotational frequency. From the spin determination of the two pairs of identical bands in {sup 152}Dy and {sup 151}Tb{sup *}, {sup 151}Tb and {sup 150}Gd{sup *}, evidence has been obtained to support the assumption of quantized alignments in units of {h bar}/2.
  • High-spin states of {sup 152}Gd have been studied via the {sup 148}Nd({sup 9}Be,5n){sup 152}Gd fusion-evaporation reaction at a beam energy of 54 MeV. The ground-state band, octupole band, and {beta} band have been extended up to spins 20{sup +}, 21{sup -}, and 16{sup +}, respectively. A possible aligned two quasineutron band, which becomes the yrast band above the spin 16{sup +}, was observed for the first time. The kinematic behaviors of the ground-state bands and yrast bands in {sup 152,154}Gd indicate that the shape of {sup 152}Gd may change with increasing rotational frequency and the difference of quadrupole deformations betweenmore » {sup 152}Gd and {sup 154}Gd obviously reduces around the first band crossing region. These observations are consistent with the theoretical calculations using cranked Woods-Saxon-Strutinsky methods. The first band crossing observed in {sup 152}Gd can be ascribed to the alignment of a pair of i{sub 13/2} neutrons. The identical ground-state bands in {sup 152}Gd and {sup 154}Dy were extended.« less