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Title: Rotational band structure in Mg 32

Abstract

There is significant evidence supporting the existence of deformed ground states within the neutron-rich N ≈ 20 neon, sodium, and magnesium isotopes that make up what is commonly called the “island of inversion.” However, the rotational band structures, which are a characteristic fingerprint of a rigid nonspherical shape, have yet to be observed. In this work, we report on a measurement and analysis of the yrast (lowest lying) rotational band in 32 Mg up to spin I = 6 + produced in a two-step projectile fragmentation reaction and observed using the state-of-the-art γ -ray tracking detector array, GRETINA ( γ -ray energy tracking in-beam nuclear array). Large-scale shell-model calculations using the SDPF-U-MIX effective interaction show excellent agreement with the new data. Moreover, a theoretical analysis of the spectrum of rotational states as a function of the pairing gap, together with cranked-shell-model calculations, provides intriguing evidence for a reduction in pairing correlations with increased angular momentum, also in line with the shell-model results.

Authors:
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Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org.:
USDOE National Nuclear Security Administration (NNSA)
OSTI Identifier:
1339166
DOE Contract Number:  
AC02-06CH11357
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physical Review C; Journal Volume: 93; Journal Issue: 3
Country of Publication:
United States
Language:
English
Subject:
73 NUCLEAR PHYSICS AND RADIATION PHYSICS

Citation Formats

Crawford, H. L., Fallon, P., Macchiavelli, A. O., Poves, A., Bader, V. M., Bazin, D., Bowry, M., Campbell, C. M., Carpenter, M. P., Clark, R. M., Cromaz, M., Gade, A., Ideguchi, E., Iwasaki, H., Langer, C., Lee, I. Y., Loelius, C., Lunderberg, E., Morse, C., Richard, A. L., Rissanen, J., Smalley, D., Stroberg, S. R., Weisshaar, D., Whitmore, K., Wiens, A., Williams, S. J., Wimmer, K., and Yamamato, T. Rotational band structure in Mg32. United States: N. p., 2016. Web. doi:10.1103/PhysRevC.93.031303.
Crawford, H. L., Fallon, P., Macchiavelli, A. O., Poves, A., Bader, V. M., Bazin, D., Bowry, M., Campbell, C. M., Carpenter, M. P., Clark, R. M., Cromaz, M., Gade, A., Ideguchi, E., Iwasaki, H., Langer, C., Lee, I. Y., Loelius, C., Lunderberg, E., Morse, C., Richard, A. L., Rissanen, J., Smalley, D., Stroberg, S. R., Weisshaar, D., Whitmore, K., Wiens, A., Williams, S. J., Wimmer, K., & Yamamato, T. Rotational band structure in Mg32. United States. doi:10.1103/PhysRevC.93.031303.
Crawford, H. L., Fallon, P., Macchiavelli, A. O., Poves, A., Bader, V. M., Bazin, D., Bowry, M., Campbell, C. M., Carpenter, M. P., Clark, R. M., Cromaz, M., Gade, A., Ideguchi, E., Iwasaki, H., Langer, C., Lee, I. Y., Loelius, C., Lunderberg, E., Morse, C., Richard, A. L., Rissanen, J., Smalley, D., Stroberg, S. R., Weisshaar, D., Whitmore, K., Wiens, A., Williams, S. J., Wimmer, K., and Yamamato, T. Tue . "Rotational band structure in Mg32". United States. doi:10.1103/PhysRevC.93.031303.
@article{osti_1339166,
title = {Rotational band structure in Mg32},
author = {Crawford, H. L. and Fallon, P. and Macchiavelli, A. O. and Poves, A. and Bader, V. M. and Bazin, D. and Bowry, M. and Campbell, C. M. and Carpenter, M. P. and Clark, R. M. and Cromaz, M. and Gade, A. and Ideguchi, E. and Iwasaki, H. and Langer, C. and Lee, I. Y. and Loelius, C. and Lunderberg, E. and Morse, C. and Richard, A. L. and Rissanen, J. and Smalley, D. and Stroberg, S. R. and Weisshaar, D. and Whitmore, K. and Wiens, A. and Williams, S. J. and Wimmer, K. and Yamamato, T.},
abstractNote = {There is significant evidence supporting the existence of deformed ground states within the neutron-rich N ≈ 20 neon, sodium, and magnesium isotopes that make up what is commonly called the “island of inversion.” However, the rotational band structures, which are a characteristic fingerprint of a rigid nonspherical shape, have yet to be observed. In this work, we report on a measurement and analysis of the yrast (lowest lying) rotational band in 32 Mg up to spin I = 6 + produced in a two-step projectile fragmentation reaction and observed using the state-of-the-art γ -ray tracking detector array, GRETINA ( γ -ray energy tracking in-beam nuclear array). Large-scale shell-model calculations using the SDPF-U-MIX effective interaction show excellent agreement with the new data. Moreover, a theoretical analysis of the spectrum of rotational states as a function of the pairing gap, together with cranked-shell-model calculations, provides intriguing evidence for a reduction in pairing correlations with increased angular momentum, also in line with the shell-model results.},
doi = {10.1103/PhysRevC.93.031303},
journal = {Physical Review C},
number = 3,
volume = 93,
place = {United States},
year = {Tue Mar 01 00:00:00 EST 2016},
month = {Tue Mar 01 00:00:00 EST 2016}
}