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Title: Selective studies of the excited rotational bands in the superdeformed nucleus {sup 151}Tb

Abstract

The experimental study of the unresolved rotational bands, forming ridge structures in {gamma}-{gamma} spectra, has been performed on the superdeformed nucleus {sup 151}Tb. {gamma} transitions from the reaction {sup 27}Al, at 155 MeV, on {sup 130}Te were measured with EUROBALL IV in high fold coincidence. The analysis of the intensities and count fluctuations of the ridge structures shows the existence of {approx_equal}30 discrete rotational bands of superdeformed nature, half of which is in direct coincidence with the superdeformed yrast band. A comparison with band mixing model predictions and with a previous work on the superdeformed nucleus {sup 143}Eu is presented.

Authors:
; ; ; ; ; ;  [1]; ; ; ; ; ; ; ; ; ; ; ; ;  [2]
  1. Dipartimento di Fisica and INFN, Sezione di Milano, Milan (Italy)
  2. Institut de Recherches Subatomiques, 23 rue du Loess, BP28 F-67037 Strasbourg (France) (and others)
Publication Date:
OSTI Identifier:
20995243
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physical Review. C, Nuclear Physics; Journal Volume: 75; Journal Issue: 4; Other Information: DOI: 10.1103/PhysRevC.75.047301; (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; ALUMINIUM 27; COMPARATIVE EVALUATIONS; ENERGY-LEVEL TRANSITIONS; EUROPIUM 143; GAMMA SPECTRA; HEAVY ION REACTIONS; MASS NUMBER; MEV RANGE 100-1000; ROTATIONAL STATES; SUPERDEFORMED NUCLEI; TELLURIUM 130; TERBIUM 151; YRAST STATES

Citation Formats

Benzoni, G., Bracco, A., Crespi, F. C. L., Conto, A. De, Leoni, S., Million, B., Montanari, D., Robin, J., Duchene, G., Curien, D., Byrski, Th., Beck, F. A., Bednarczyk, P., Courtin, S., Dorvaux, O., Gall, B. J. P., Joshi, P., Nourreddine, A., Piqueras, I., and Vivien, J. P. Selective studies of the excited rotational bands in the superdeformed nucleus {sup 151}Tb. United States: N. p., 2007. Web. doi:10.1103/PHYSREVC.75.047301.
Benzoni, G., Bracco, A., Crespi, F. C. L., Conto, A. De, Leoni, S., Million, B., Montanari, D., Robin, J., Duchene, G., Curien, D., Byrski, Th., Beck, F. A., Bednarczyk, P., Courtin, S., Dorvaux, O., Gall, B. J. P., Joshi, P., Nourreddine, A., Piqueras, I., & Vivien, J. P. Selective studies of the excited rotational bands in the superdeformed nucleus {sup 151}Tb. United States. doi:10.1103/PHYSREVC.75.047301.
Benzoni, G., Bracco, A., Crespi, F. C. L., Conto, A. De, Leoni, S., Million, B., Montanari, D., Robin, J., Duchene, G., Curien, D., Byrski, Th., Beck, F. A., Bednarczyk, P., Courtin, S., Dorvaux, O., Gall, B. J. P., Joshi, P., Nourreddine, A., Piqueras, I., and Vivien, J. P. Sun . "Selective studies of the excited rotational bands in the superdeformed nucleus {sup 151}Tb". United States. doi:10.1103/PHYSREVC.75.047301.
@article{osti_20995243,
title = {Selective studies of the excited rotational bands in the superdeformed nucleus {sup 151}Tb},
author = {Benzoni, G. and Bracco, A. and Crespi, F. C. L. and Conto, A. De and Leoni, S. and Million, B. and Montanari, D. and Robin, J. and Duchene, G. and Curien, D. and Byrski, Th. and Beck, F. A. and Bednarczyk, P. and Courtin, S. and Dorvaux, O. and Gall, B. J. P. and Joshi, P. and Nourreddine, A. and Piqueras, I. and Vivien, J. P.},
abstractNote = {The experimental study of the unresolved rotational bands, forming ridge structures in {gamma}-{gamma} spectra, has been performed on the superdeformed nucleus {sup 151}Tb. {gamma} transitions from the reaction {sup 27}Al, at 155 MeV, on {sup 130}Te were measured with EUROBALL IV in high fold coincidence. The analysis of the intensities and count fluctuations of the ridge structures shows the existence of {approx_equal}30 discrete rotational bands of superdeformed nature, half of which is in direct coincidence with the superdeformed yrast band. A comparison with band mixing model predictions and with a previous work on the superdeformed nucleus {sup 143}Eu is presented.},
doi = {10.1103/PHYSREVC.75.047301},
journal = {Physical Review. C, Nuclear Physics},
number = 4,
volume = 75,
place = {United States},
year = {Sun Apr 15 00:00:00 EDT 2007},
month = {Sun Apr 15 00:00:00 EDT 2007}
}
  • The spin of the lowest level observed in the superdeformed band in {sup 152}Dy is determined to be {ital I}{sub 0}=25 rather than the previously assigned {ital I}{sub 0}=22. As a result, we have {ital scrI}{sup (1)}{gt}{ital scrI}{sup (2)} and both {ital scrI}{sup (1)} and {ital scrI}{sup (2)} decrease very slowly with rotational frequency. From the spin determination of the two pairs of identical bands in {sup 152}Dy and {sup 151}Tb{sup *}, {sup 151}Tb and {sup 150}Gd{sup *}, evidence has been obtained to support the assumption of quantized alignments in units of {h bar}/2.
  • Relative intensities of the yrast and the first excited superdeformed bands in [sup 151]Tb have been accurately measured, with the EUROGAM spectrometer. It is shown that he excited band depopulates at the same freqeuncy and spin as its identical band in the isotone [sup 152]Dy whereas the yrast band deexcites at higher rotational frequency and spin even though it is much lower in excitation energy. A classification of superdeformed bands in the [ital A][similar to]150 mass region indicates that the decay-out mechanism is strongly affected by neutron pairing correlations and the occupancy of high-[ital N] intruder orbitals.
  • The Euroball array has been used to search for linking transitions between the superdeformed (SD) and the normal deformed (ND) wells in {sup 151}Tb. Many {gamma} rays in the energy range 2-4 MeV have been observed in coincidence with the yrast SD band. It is proposed that the highest energy transition of 3748 keV and the strongest line (2818 keV) of the previously observed transitions both decay from the same SD level as their links with the ND states have been identified. The current spectra have insufficient statistics to completely identify the decay point in the SD band. Theoretical calculationsmore » covering SD bands in the A{approx_equal}150 region enable the two possible spin assignments to be compared with experimental data on proposed links in {sup 149}Gd and {sup 152}Dy. It is concluded that the energy of the lowest SD band member in {sup 151}Tb has an excitation energy of 12861 keV and a spin of 65/2{sup +}.« less