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Title: Spin dependence of k-mixing, strong configuration mixing and electromagnetic properties of {sup 178}Hf.

Abstract

The combined data of two Coulomb excitation experiments has verified the purely electromagnetic population of the K{pi} = 4{sup +}, 6{sup +}, 8{sup -}, and 16{sup +} rotational bands in {sup 178}Hf via 2 {le} {nu} {le} 14 K-forbidden transitions, quantifying the breakdown of the K-selection rule with increasing spin in the low-K bands. The {gamma}{sup -}, 4{sup +}, and 6{sup +} bands were extended, and four new states in a rotational band were tentatively assigned to a previously known K{pi} = 0{sup +} band. The quasiparticle structure of the 6{sup +} (t 1/2 = 77 ns) and 8{sup -} (t 1/2 = 4s) isomer bands were evaluated, showing that the gyromagnetic ratios of the 6{sup +} isomer band are consistent with a pure {pi} 7/2{sup +}[404],{pi} 5/2{sup +}[402] structure. The 8{sup -} isomer band at 1147 keV and the second 8{sup -} band at 1479 keV, thought to be predominantly {nu} 7/2{sup -}[514], {nu} 9/2{sup +}[624] and {pi} 9/2{sup -}[514], {pi}7/2{sup +}[404], respectively, are mixed to a degree approaching the strong-mixing limit. Based on measured <K{pi} = 16{sup +} {parallel} E2 {parallel} K{pi} = 0{sup +}> matrix elements, it was shown that heavy-ion bombardment could depopulate the 16{sup +}more » isomer at the {approx}1% level, although no states were found that would mediate photodeexcitation of the isomer via low-energy x-ray absorption.« less

Authors:
; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; more »; ; ; ; ; ; ; ; ; ; ; ; ; ; « less
Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org.:
USDOE Office of Science (SC); National Science Foundation (NSF); US Air Force Office of Scientific Research (AFOSR); Polish State Committee for Scientific Research
OSTI Identifier:
940692
Report Number(s):
ANL/PHY/JA-57737
Journal ID: ISSN 0556-2813; PRVCAN; TRN: US0807171
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:
74 ATOMIC AND MOLECULAR PHYSICS; HAFNIUM 178; ROTATIONAL STATES; FORBIDDEN TRANSITIONS; BREAKDOWN; CONFIGURATION MIXING; COULOMB EXCITATION; GYROMAGNETIC RATIO; ISOMERS

Citation Formats

Hayes, A.B., Cline, D., Wu, C.Y., Ai, H., Amro, H., Beausang, C., Casten, R.F., Gerl, J., Hecht, A.A., Heinz, A., Hua, H., Hughes, R., Janssens, R.V.F, Lister, C.J., Macchiavelli, A.O., Meyer, D.A., Moore, E.F., Napiorkowski, P., Pardo, R.C., Schlegel, Ch., Seweryniak, D., Simon, W.M., Srebrny, J., Teng, R., Vetter, K., Physics, Univ. of Rochester, LLNL, Yale Univ., Univ. of Richmond, GSI, Peking Univ., Lawrence Berkeley National Lab., and Warsaw Univ.. Spin dependence of k-mixing, strong configuration mixing and electromagnetic properties of {sup 178}Hf.. United States: N. p., 2007. Web. doi:10.1103/PhysRevC.75.034308.
Hayes, A.B., Cline, D., Wu, C.Y., Ai, H., Amro, H., Beausang, C., Casten, R.F., Gerl, J., Hecht, A.A., Heinz, A., Hua, H., Hughes, R., Janssens, R.V.F, Lister, C.J., Macchiavelli, A.O., Meyer, D.A., Moore, E.F., Napiorkowski, P., Pardo, R.C., Schlegel, Ch., Seweryniak, D., Simon, W.M., Srebrny, J., Teng, R., Vetter, K., Physics, Univ. of Rochester, LLNL, Yale Univ., Univ. of Richmond, GSI, Peking Univ., Lawrence Berkeley National Lab., & Warsaw Univ.. Spin dependence of k-mixing, strong configuration mixing and electromagnetic properties of {sup 178}Hf.. United States. doi:10.1103/PhysRevC.75.034308.
Hayes, A.B., Cline, D., Wu, C.Y., Ai, H., Amro, H., Beausang, C., Casten, R.F., Gerl, J., Hecht, A.A., Heinz, A., Hua, H., Hughes, R., Janssens, R.V.F, Lister, C.J., Macchiavelli, A.O., Meyer, D.A., Moore, E.F., Napiorkowski, P., Pardo, R.C., Schlegel, Ch., Seweryniak, D., Simon, W.M., Srebrny, J., Teng, R., Vetter, K., Physics, Univ. of Rochester, LLNL, Yale Univ., Univ. of Richmond, GSI, Peking Univ., Lawrence Berkeley National Lab., and Warsaw Univ.. Mon . "Spin dependence of k-mixing, strong configuration mixing and electromagnetic properties of {sup 178}Hf.". United States. doi:10.1103/PhysRevC.75.034308.
@article{osti_940692,
title = {Spin dependence of k-mixing, strong configuration mixing and electromagnetic properties of {sup 178}Hf.},
author = {Hayes, A.B. and Cline, D. and Wu, C.Y. and Ai, H. and Amro, H. and Beausang, C. and Casten, R.F. and Gerl, J. and Hecht, A.A. and Heinz, A. and Hua, H. and Hughes, R. and Janssens, R.V.F and Lister, C.J. and Macchiavelli, A.O. and Meyer, D.A. and Moore, E.F. and Napiorkowski, P. and Pardo, R.C. and Schlegel, Ch. and Seweryniak, D. and Simon, W.M. and Srebrny, J. and Teng, R. and Vetter, K. and Physics and Univ. of Rochester and LLNL and Yale Univ. and Univ. of Richmond and GSI and Peking Univ. and Lawrence Berkeley National Lab. and Warsaw Univ.},
abstractNote = {The combined data of two Coulomb excitation experiments has verified the purely electromagnetic population of the K{pi} = 4{sup +}, 6{sup +}, 8{sup -}, and 16{sup +} rotational bands in {sup 178}Hf via 2 {le} {nu} {le} 14 K-forbidden transitions, quantifying the breakdown of the K-selection rule with increasing spin in the low-K bands. The {gamma}{sup -}, 4{sup +}, and 6{sup +} bands were extended, and four new states in a rotational band were tentatively assigned to a previously known K{pi} = 0{sup +} band. The quasiparticle structure of the 6{sup +} (t 1/2 = 77 ns) and 8{sup -} (t 1/2 = 4s) isomer bands were evaluated, showing that the gyromagnetic ratios of the 6{sup +} isomer band are consistent with a pure {pi} 7/2{sup +}[404],{pi} 5/2{sup +}[402] structure. The 8{sup -} isomer band at 1147 keV and the second 8{sup -} band at 1479 keV, thought to be predominantly {nu} 7/2{sup -}[514], {nu} 9/2{sup +}[624] and {pi} 9/2{sup -}[514], {pi}7/2{sup +}[404], respectively, are mixed to a degree approaching the strong-mixing limit. Based on measured <K{pi} = 16{sup +} {parallel} E2 {parallel} K{pi} = 0{sup +}> matrix elements, it was shown that heavy-ion bombardment could depopulate the 16{sup +} isomer at the {approx}1% level, although no states were found that would mediate photodeexcitation of the isomer via low-energy x-ray absorption.},
doi = {10.1103/PhysRevC.75.034308},
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 combined data of two Coulomb excitation experiments has verified the purely electromagnetic population of the K{sup {pi}}=4{sup +},6{sup +},8{sup -}, and 16{sup +} rotational bands in {sup 178}Hf via 2{<=}{nu}{<=}14 K-forbidden transitions, quantifying the breakdown of the K-selection rule with increasing spin in the low-K bands. The {gamma}-, 4{sup +}, and 6{sup +} bands were extended, and four new states in a rotational band were tentatively assigned to a previously known K{sup {pi}}=0{sup +} band. The quasiparticle structure of the 6{sup +} (t{sub (1/2)}=77 ns) and 8{sup -} (t{sub (1/2)}=4 s) isomer bands were evaluated, showing that the gyromagneticmore » ratios of the 6{sup +} isomer band are consistent with a pure {pi}(7/2){sup +}[404],{pi}(5/2){sup +}[402] structure. The 8{sup -} isomer band at 1147 keV and the second 8{sup -} band at 1479 keV, thought to be predominantly {nu}(7/2){sup -}[514],{nu}(9/2){sup +}[624] and {pi}(9/2){sup -}[514],{pi}(7/2){sup +}[404], respectively, are mixed to a degree approaching the strong-mixing limit. Based on measured <K{sup {pi}}=16{sup +} parallel E 2 parallel K{sup {pi}}=0{sup +}> matrix elements, it was shown that heavy-ion bombardment could depopulate the 16{sup +} isomer at the {approx}1% level, although no states were found that would mediate photodeexcitation of the isomer via low-energy x-ray absorption.« less
  • No abstract prepared.
  • 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