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Title: Breakdown of K Selection in {sup 178}Hf

Abstract

Coulomb activation of the four quasiparticle K{sup {pi}}=16{sup +} {sup 178}Hf isomer (t{sub 1/2}=31 y) has led to the measurement of a set of E{lambda} matrix elements coupling the isomer band to the ground band. The present data combined with earlier {sup 178}Hf Coulomb excitation data have probed the K components in the wave functions and revealed the onset and saturation of K mixing in low-K bands, whereas the mixing is negligible in the high-K bands. The implications can be applied to other quadrupole-deformed nuclei.

Authors:
; ; ; ;  [1]; ; ; ; ; ; ;  [2];  [3]; ; ;  [4]; ; ; ;  [5]
  1. Nuclear Structure Research Laboratory, Department of Physics, University of Rochester, Rochester, New York 14627 (United States)
  2. Wright Nuclear Structure Laboratory, Yale University, New Haven, Connecticut 06520 (United States)
  3. Physics Department, University of Richmond, Richmond, Virginia 23173 (United States)
  4. GSI, Gesellschaft fuer Schwerionenforschung, Planckstrasse 1, D-64291 Darmstadt (Germany)
  5. Physics Division, Argonne National Laboratory, Argonne, Illinois 60439 (United States) (and others)
Publication Date:
OSTI Identifier:
20777008
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physical Review Letters; Journal Volume: 96; Journal Issue: 4; Other Information: DOI: 10.1103/PhysRevLett.96.042505; (c) 2006 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; COULOMB EXCITATION; DEFORMED NUCLEI; HAFNIUM 178; HIGH SPIN STATES; ISOMERS; MATRIX ELEMENTS; QUADRUPOLES; ROTATIONAL STATES; WAVE FUNCTIONS

Citation Formats

Hayes, A.B., Cline, D., Wu, C.Y., Simon, M.W., Teng, R., Ai, J., Amro, H., Casten, R.F., Hecht, A.A., Heinz, A., Hughes, R., Meyer, D.A., Beausang, C., Gerl, J., Schlegel, Ch., Wollersheim, H.J., Janssens, R.V.F., Lister, C.J., Moore, E.F., and Pardo, R.C. Breakdown of K Selection in {sup 178}Hf. United States: N. p., 2006. Web. doi:10.1103/PhysRevLett.96.042505.
Hayes, A.B., Cline, D., Wu, C.Y., Simon, M.W., Teng, R., Ai, J., Amro, H., Casten, R.F., Hecht, A.A., Heinz, A., Hughes, R., Meyer, D.A., Beausang, C., Gerl, J., Schlegel, Ch., Wollersheim, H.J., Janssens, R.V.F., Lister, C.J., Moore, E.F., & Pardo, R.C. Breakdown of K Selection in {sup 178}Hf. United States. doi:10.1103/PhysRevLett.96.042505.
Hayes, A.B., Cline, D., Wu, C.Y., Simon, M.W., Teng, R., Ai, J., Amro, H., Casten, R.F., Hecht, A.A., Heinz, A., Hughes, R., Meyer, D.A., Beausang, C., Gerl, J., Schlegel, Ch., Wollersheim, H.J., Janssens, R.V.F., Lister, C.J., Moore, E.F., and Pardo, R.C. Fri . "Breakdown of K Selection in {sup 178}Hf". United States. doi:10.1103/PhysRevLett.96.042505.
@article{osti_20777008,
title = {Breakdown of K Selection in {sup 178}Hf},
author = {Hayes, A.B. and Cline, D. and Wu, C.Y. and Simon, M.W. and Teng, R. and Ai, J. and Amro, H. and Casten, R.F. and Hecht, A.A. and Heinz, A. and Hughes, R. and Meyer, D.A. and Beausang, C. and Gerl, J. and Schlegel, Ch. and Wollersheim, H.J. and Janssens, R.V.F. and Lister, C.J. and Moore, E.F. and Pardo, R.C.},
abstractNote = {Coulomb activation of the four quasiparticle K{sup {pi}}=16{sup +} {sup 178}Hf isomer (t{sub 1/2}=31 y) has led to the measurement of a set of E{lambda} matrix elements coupling the isomer band to the ground band. The present data combined with earlier {sup 178}Hf Coulomb excitation data have probed the K components in the wave functions and revealed the onset and saturation of K mixing in low-K bands, whereas the mixing is negligible in the high-K bands. The implications can be applied to other quadrupole-deformed nuclei.},
doi = {10.1103/PhysRevLett.96.042505},
journal = {Physical Review Letters},
number = 4,
volume = 96,
place = {United States},
year = {Fri Feb 03 00:00:00 EST 2006},
month = {Fri Feb 03 00:00:00 EST 2006}
}
  • The decays of the high-spin isomers of $sup 178$Ta (2.45 h) and $sup 178$Lu (23.8 min) to the two strongly admixed K/sup $pi$/ = 8$sup -$ states in $sup 178$Hf were reinvestigated. The main features of the previously reported decay schemes are confirmed and several long-standing ambiguities are resolved. The results of this investigation indicate that the 1147-keV level is largely the two-neutron state and the 1479-keV level is largely the two-proton state in $sup 178$Hf. They are found to be 34% admixed with one another. This mixing value is in good agreement with the value deduced from the M1/E2more » cascade ratios of the 1147-keV band and from the comparison of the E1 ($nu$ = 7) hindrance factors of these two states in this mass region. The band-mixing matrix element for these two states was found to be in agreement with the recent theory which introduces the residual neutron-proton interaction to account for the mixing. The spin- parity of $sup 178$Lu/sup m/ (23.8 min) was deduced to be K/sup $pi$/ = 9$sup -$ with a possible Nilsson configuration of 9/2$sup -$ [514] /subp/, 9/2$sup +$ [624] /subn/. (AIP)« less
  • The Coulomb excitation experiment on the 178Hf was performed using 650 MeV beam of 136Xe. The first observation of discrete transitions in the K π = 8 - isomeric band. Coulomb excited from K π = 0+ ground state, is reported. The possible mechanisms of El coupling of the ground state band and the isomeric band is discussed.
  • The [ital K][sup [pi]]=8[sup [minus]] isomer at 1147.4 keV in [sup 178]Hf was populated in a Coulomb excitation experiment with [sup 130]Te ions. The measured cross section for this isomer was 2.7[plus minus][sub 1.4][sup 1.9], 4.3[plus minus][sub 2.0][sup 3.4], and 7.5[plus minus][sub 3.2][sup 6.1] mb for three beam energies below the Coulomb barrier, namely 560, 590, and 620 MeV. If one assumes that the projection of the total angular momentum on the symmetry axis, [ital K], is only an approximate quantum number, the population of this isomer can be reproduced via direct [ital E]3 excitations of odd spin members ofmore » the isomeric band from the ground state band.« less