Alignment Delays in the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi mathvariant="italic">N</mi><mspace></mspace><mo>=</mo><mspace></mspace><mi mathvariant="italic">Z</mi></math> Nuclei <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mmultiscripts><mrow><mi>K</mi></mrow><mprescripts></mprescripts><mrow></mrow><mrow><mn>72</mn></mrow><mrow></mrow><mrow></mrow></mmultiscripts></mrow><mi>r</mi></math>, <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mmultiscripts><mrow><mi>S</mi></mrow><mprescripts></mprescripts><mrow></mrow><mrow><mn>76</mn></mrow><mrow></mrow><mrow></mrow></mmultiscripts></mrow><mi>r</mi></math>, and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mmultiscripts><mrow><mi>Z</mi></mrow><mprescripts></mprescripts><mrow></mrow><mrow><mn>80</mn></mrow><mrow></mrow><mrow></mrow></mmultiscripts></mrow><mi>r</mi></math>

S. M. Fischer; C. J. Lister; D. P. Balamuth; R. Bauer; J. A. Becker; L. A. Bernstein; M. P. Carpenter; J. Durell; N. Fotiades; S. J. Freeman; P. E. Garrett; P. A. Hausladen; R. V. F. Janssens; D. Jenkins; M. Leddy; J. Ressler; J. Schwartz; D. Svelnys; D. G. Sarantites; D. Seweryniak; B. J. Varley; R. Wyss

doi:10.1103/PhysRevLett.87.132501

Alignment Delays in the $N = Z$ Nuclei ${}^{72}K r$ , ${}^{76}S r$ , and ${}^{80}Z r$

S. M. Fischer, C. J. Lister, D. P. Balamuth, R. Bauer, J. A. Becker, L. A. Bernstein, M. P. Carpenter, J. Durell, N. Fotiades, S. J. Freeman, P. E. Garrett, P. A. Hausladen, R. V. F. Janssens, D. Jenkins, M. Leddy, J. Ressler, J. Schwartz, D. Svelnys, D. G. Sarantites, D. Seweryniak, B. J. Varley, and R. Wyss

Phys. Rev. Lett. 87, 132501 – Published 4 September 2001

Abstract

The ground state rotational bands of the $N = Z$ nuclei $^{72} Kr$ , $^{76} Sr$ , and $^{80} Zr$ have been extended into the angular momentum region where rotation alignment of particles is normally expected. By measuring the moments of inertia of these bands we have observed a consistent increase in the rotational frequency required to start pair breaking, when compared to neighboring nuclei. $^{72} Kr$ shows the most marked effect. It has been widely suggested that these “delayed alignments” arise from $np$ -pairing correlations. However, alignment frequencies are very sensitive to shape degrees of freedom and normal pairing, so the new experimental observations are still open to interpretation.

Received 22 March 2001

DOI:https://doi.org/10.1103/PhysRevLett.87.132501

Authors & Affiliations

S. M. Fischer¹, C. J. Lister², D. P. Balamuth³, R. Bauer⁴, J. A. Becker⁴, L. A. Bernstein⁴, M. P. Carpenter², J. Durell⁵, N. Fotiades⁶, S. J. Freeman⁵, P. E. Garrett⁴, P. A. Hausladen³, R. V. F. Janssens², D. Jenkins^2,3, M. Leddy⁵, J. Ressler⁷, J. Schwartz², D. Svelnys¹, D. G. Sarantites⁸, D. Seweryniak², B. J. Varley⁵, and R. Wyss⁹

¹Department of Physics, DePaul University, Chicago, Illinois 60614
²Physics Division, Argonne National Laboratory, Argonne, Illinois 60439
³Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, Pennsylvania 19104
⁴Physics Division, Lawrence Livermore National Laboratory, Livermore, California 94550
⁵Department of Physics, University of Manchester, Manchester M13 9PL, United Kingdom
⁶Department of Physics and Astronomy, Rutgers University, New Brunswick, New Jersey 08903
⁷Department of Chemistry, University of Maryland, College Park, Maryland 20742
⁸Department of Chemistry, Washington University, St. Louis, Missouri 63130
⁹Royal Institute of Technology, KTH-Frescati, Frescativ 24, 104 05, Stockholm, Sweden