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Title: Sign of the g factor of the 4{sub 1}{sup +} state in {sup 68}Zn

Abstract

In two recent papers a negative g factor was reported for the 4{sub 1}{sup +} state in {sup 68}Zn. The negative sign is unexpected. It is not consistent with the systematics of g factors in the neighboring Zn and Ge isotopes and could not be explained by shell-model calculations even when significant contributions of the 0g{sub 9/2} neutrons were included. Therefore, an independent g factor measurement was performed, using {sup 68}Zn projectiles which were accelerated to a higher energy in order to obtain a higher yield for the 4{sub 1}{sup +} state. The new measurement yielded a positive g factor, g(4{sub 1}{sup +})=+0.6(3), which agrees with the results of full fp spherical shell model calculations, as well as with Z/A, the collective model prediction.

Authors:
; ; ; ; ;  [1];  [2]; ; ; ; ; ; ;  [3];  [3];  [4]; ; ; ;  [5]
  1. Department of Physics and Astronomy, Rutgers University, New Brunswick, New Jersey 08903 (United States)
  2. Geology and Physics Department, University of Southern Indiana, Evansville, Indiana 47712 (United States)
  3. A. W. Wright Nuclear Structure Laboratory, Yale University, New Haven, Connecticut 06520 (United States)
  4. (United Kingdom)
  5. Department of Physics, University of Richmond, Richmond, Virginia 23173 (United States)
Publication Date:
OSTI Identifier:
20990993
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physical Review. C, Nuclear Physics; Journal Volume: 75; Journal Issue: 2; Other Information: DOI: 10.1103/PhysRevC.75.021302; (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; COLLECTIVE MODEL; GERMANIUM ISOTOPES; LANDE FACTOR; NEUTRONS; SHELL MODELS; SPHERICAL CONFIGURATION; ZINC 68

Citation Formats

Boutachkov, P., Benczer-Koller, N., Kumbartzki, G. J., Escuderos, A., Sharon, Y. Y., Zamick, L., Robinson, S. J. Q., Ai, H., Guerdal, G., Heinz, A., McCutchan, E. A., Quian, J., Werner, V., Williams, E., Chamberlain, M., Department of Physics, University of Surrey, Guildford, Surrey, Aleksandrova, K., Copos, C. A., Kovacheva, D. A., and Manchev, P.. Sign of the g factor of the 4{sub 1}{sup +} state in {sup 68}Zn. United States: N. p., 2007. Web. doi:10.1103/PHYSREVC.75.021302.
Boutachkov, P., Benczer-Koller, N., Kumbartzki, G. J., Escuderos, A., Sharon, Y. Y., Zamick, L., Robinson, S. J. Q., Ai, H., Guerdal, G., Heinz, A., McCutchan, E. A., Quian, J., Werner, V., Williams, E., Chamberlain, M., Department of Physics, University of Surrey, Guildford, Surrey, Aleksandrova, K., Copos, C. A., Kovacheva, D. A., & Manchev, P.. Sign of the g factor of the 4{sub 1}{sup +} state in {sup 68}Zn. United States. doi:10.1103/PHYSREVC.75.021302.
Boutachkov, P., Benczer-Koller, N., Kumbartzki, G. J., Escuderos, A., Sharon, Y. Y., Zamick, L., Robinson, S. J. Q., Ai, H., Guerdal, G., Heinz, A., McCutchan, E. A., Quian, J., Werner, V., Williams, E., Chamberlain, M., Department of Physics, University of Surrey, Guildford, Surrey, Aleksandrova, K., Copos, C. A., Kovacheva, D. A., and Manchev, P.. Thu . "Sign of the g factor of the 4{sub 1}{sup +} state in {sup 68}Zn". United States. doi:10.1103/PHYSREVC.75.021302.
@article{osti_20990993,
title = {Sign of the g factor of the 4{sub 1}{sup +} state in {sup 68}Zn},
author = {Boutachkov, P. and Benczer-Koller, N. and Kumbartzki, G. J. and Escuderos, A. and Sharon, Y. Y. and Zamick, L. and Robinson, S. J. Q. and Ai, H. and Guerdal, G. and Heinz, A. and McCutchan, E. A. and Quian, J. and Werner, V. and Williams, E. and Chamberlain, M. and Department of Physics, University of Surrey, Guildford, Surrey and Aleksandrova, K. and Copos, C. A. and Kovacheva, D. A. and Manchev, P.},
abstractNote = {In two recent papers a negative g factor was reported for the 4{sub 1}{sup +} state in {sup 68}Zn. The negative sign is unexpected. It is not consistent with the systematics of g factors in the neighboring Zn and Ge isotopes and could not be explained by shell-model calculations even when significant contributions of the 0g{sub 9/2} neutrons were included. Therefore, an independent g factor measurement was performed, using {sup 68}Zn projectiles which were accelerated to a higher energy in order to obtain a higher yield for the 4{sub 1}{sup +} state. The new measurement yielded a positive g factor, g(4{sub 1}{sup +})=+0.6(3), which agrees with the results of full fp spherical shell model calculations, as well as with Z/A, the collective model prediction.},
doi = {10.1103/PHYSREVC.75.021302},
journal = {Physical Review. C, Nuclear Physics},
number = 2,
volume = 75,
place = {United States},
year = {Thu Feb 15 00:00:00 EST 2007},
month = {Thu Feb 15 00:00:00 EST 2007}
}
  • The g factor of the 4{sub 1}{sup +} state in {sup 68}Zn was remeasured with improved energy resolution of the detectors used. The value obtained is consistent with the previous result of a negative g factor, thus confirming the dominant 0g{sub 9/2} neutron nature of the 4{sub 1}{sup +} state. In addition, the accuracy of the g factors of the 2{sub 1}{sup +},2{sub 2}{sup +}, and 3{sub 1}{sup -} states has been improved and their lifetimes were well reproduced. New large-scale shell-model calculations based on a {sup 56}Ni core and a 0f{sub 5/2}1p0g{sub 9/2} model space yield a theoretical value,more » g(4{sub 1}{sup +})=+0.008. Although the calculated value is small, it cannot fully explain the experimental value, g(4{sub 1}{sup +})=-0.37(17). The magnitude of the deduced B(E2) of the 4{sub 1}{sup +} and 2{sub 1}{sup +} transitions is, however, rather well described. These results demonstrate again the importance of g factor measurements for nuclear structure determinations because of their specific sensitivity to detailed proton and neutron components in the nuclear wave functions.« less
  • We have remeasured and have redetermined the g factor for the 4{sub 1}{sup +} state in {sup 68}Zn following inconsistencies between earlier measurements and a recent result. We have reanalyzed several former measurements by applying an alternative analysis procedure, which allows for determining the precession effect separately for each gamma detector implying less uncertainties in the background subtraction for the relevant spectra. In addition, all measured g-factor and B(E2) data for the first 2{sup +} and 4{sup +} states in all stable even-A Zn isotopes and the radioactive {sup 62}Zn, are compared with new large-scale shell model calculations based onmore » the most advanced effective interaction in the fpg-shell model space.« less
  • The g factors of the short-lived 2{sub 1}{sup +},4{sub 1}{sup +}, and 3{sub 1}{sup -} states in {sup 64}Zn and the 2{sub 1}{sup +},4{sub 1}{sup +},2{sub 2}{sup +}, and 3{sub 1}{sup -} states in {sup 68}Zn have been measured using the combined technique of projectile Coulomb excitation in inverse kinematics and transient magnetic fields. In addition, B(E2)'s have been deduced from remeasured lifetimes of several excited states employing the Doppler-shift-attenuation method. Whereas the present data for the 2{sub 1}{sup +} states agree very well with our previous results, the g factors of the other states have been determined for themore » first time. All experimental data were compared with results from large-scale shell model calculations based on proton and neutron configurations in the fp and fpg model spaces with {sup 40}Ca and {sup 56}Ni as inert cores, respectively.« less
  • The g factor of the 4{sub 1}{sup +} state in {sup 66}Zn has been measured for the first time employing the technique of projectile Coulomb excitation in inverse kinematics combined with transient magnetic fields. The lifetime of this state, {tau}(4{sub 1}{sup +})=1.1(2) ps, which has been remeasured by the Doppler shift attenuation method, is twice as large as a previously determined value. Both the deduced B(E2;4{sub 1}{sup +}{yields}2{sub 1}{sup +})=133(24) e{sup 2} fm{sup 4} and the g factor of the 4{sub 1}{sup +} state, g(4{sub 1}{sup +})=+0.65(20), were interpreted, together with results for the 2{sub 1}{sup +} state, in themore » framework of shell-model calculations based on a {sup 56}Ni closed-shell core. The present results are also compared with those for neighboring {sup 64}Zn and {sup 68}Zn that were obtained in previous measurements by the same technique.« less
  • We report precision atomic-beam measurements which yield a value for the helium-hydrogen g-factor ratio: ,I/sup 2/S/sub 1/2/) = 1-23.25(30) x 10/sup -6/. This value is in very good agreement with theory, and with an earlier, less precise atomic-beam measurement; it is in serious disagreement, however, with a recent optical-pumping determination which had seemed to cast doubt upon the adequacy of the theory. (auth)