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Title: Dipole resonances in the electroexcitation of the {sup 24}Mg nucleus

Abstract

The wave functions and form factors of E1 excited states of the deformed nucleus {sup 24}Mg are obtained within the particle-core coupling version of the shell model by using spectroscopic data on direct nucleon-pickup reactions. A comparison of the calculated E1-strength distributions with experimental cross sections shows the validity of the theoretical approach used, which is based on connections between direct and resonance nuclear reactions.

Authors:
;  [1]
  1. Moscow State University, Institute of Nuclear Physics (Russian Federation)
Publication Date:
OSTI Identifier:
21075903
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physics of Atomic Nuclei; Journal Volume: 70; Journal Issue: 4; Other Information: DOI: 10.1134/S1063778807040047; Copyright (c) 2007 Nauka/Interperiodica; Article Copyright (c) 2007 Pleiades Publishing, Ltd; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
74 ATOMIC AND MOLECULAR PHYSICS; COMPARATIVE EVALUATIONS; COUPLING; CROSS SECTIONS; DEFORMED NUCLEI; DIPOLES; DISTRIBUTION; EXCITED STATES; FORM FACTORS; MAGNESIUM 24; NUCLEONS; PICKUP REACTIONS; RESONANCE; SHELL MODELS; WAVE FUNCTIONS

Citation Formats

Goncharova, N. G., E-mail: ngg@srd.sinp.msu.ru, and Pronkina, N. D.. Dipole resonances in the electroexcitation of the {sup 24}Mg nucleus. United States: N. p., 2007. Web. doi:10.1134/S1063778807040047.
Goncharova, N. G., E-mail: ngg@srd.sinp.msu.ru, & Pronkina, N. D.. Dipole resonances in the electroexcitation of the {sup 24}Mg nucleus. United States. doi:10.1134/S1063778807040047.
Goncharova, N. G., E-mail: ngg@srd.sinp.msu.ru, and Pronkina, N. D.. Sun . "Dipole resonances in the electroexcitation of the {sup 24}Mg nucleus". United States. doi:10.1134/S1063778807040047.
@article{osti_21075903,
title = {Dipole resonances in the electroexcitation of the {sup 24}Mg nucleus},
author = {Goncharova, N. G., E-mail: ngg@srd.sinp.msu.ru and Pronkina, N. D.},
abstractNote = {The wave functions and form factors of E1 excited states of the deformed nucleus {sup 24}Mg are obtained within the particle-core coupling version of the shell model by using spectroscopic data on direct nucleon-pickup reactions. A comparison of the calculated E1-strength distributions with experimental cross sections shows the validity of the theoretical approach used, which is based on connections between direct and resonance nuclear reactions.},
doi = {10.1134/S1063778807040047},
journal = {Physics of Atomic Nuclei},
number = 4,
volume = 70,
place = {United States},
year = {Sun Apr 15 00:00:00 EDT 2007},
month = {Sun Apr 15 00:00:00 EDT 2007}
}
  • Highly excited multipole resonances of /sup 24/Mg between 9 and 34 MeV excitation energy have been investigated by inelastic electron scattering for incident energies in the 102 and 200 MeV range. Prominent giant dipole resonances were observed at 18.9 and 20 MeV excitation energy, with a shape which is very similar to the shape of the photoneutron cross section. Over twenty-five quadrupole and twenty octupole resonances were identified and separated by means of the multipole expansion method. The giant dipole strength exhausts (85/sup +9//sub -/17)% of the isovector dipole energy-weighted sum rule. The quadrupole and the octupole strength exhaust (117more » +- 23)% and (115 +- 23)% of the corresponding isoscalar energy-weighted sum rule, respectively. Evidence for the excitation of higher multipole states such as hexadecapole transitions was also found in the excitation energy region studied.« less
  • On the basis of spectroscopic information about direct pickup reactions, the multipole magnetic resonances M2, M4, and M6 of the {sup 26}Mg nucleus are calculated within the particle-core coupling version of the multiparticle shell model. The excitation-energy distribution of the form factors for the multipole magnetic 1({Dirac_h}/2{pi}){omega} resonances is obtained for momentum transfers to a nucleus up to 2 fm{sup -1}. A comparison of the results of the calculations for the M6 form factors with corresponding experimental data confirms that the adopted model approximations are realistic.
  • We present the giant electric-dipole and electric-quadrupole cross sections of /sup 42/Ca and /sup 44/Ca measured by inelastic electron scattering with incident energies between 124 and 250 MeV. Spectra were decomposed into dipole, quadrupole, and other higher multipole components. The giant dipole resonances in both nuclei have a large width of approximately 12 MeV, with at least two gross resonance structures. The quadrupole resonances are distributed in several clusters between 10 and 22 MeV, depleting (61 +- 9)% in /sup 42/Ca and (46 +- 7)% in /sup 44/Ca of the isoscalar energy-weighted sum rule, respectively. Higher multipole resonances were alsomore » found in the same excitation energy region. The observed structure in the dipole and quadrupole resonances are examined in terms of collective model, and it is suggested that the splitting of the dipole resonance revealed in /sup 44/Ca may reflect the effect of nuclear deformation.« less