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Titolo:
Giant resonance spectroscopy of Ca-40 with the (e,e ' x) reaction (II): Multipole decomposition of 4 pi-integrated spectra and angular correlations
Autore:
Diesener, H; Helm, U; Huck, V; von Neumann-Cosel, P; Rangacharyulu, C; Richter, A; Schrieder, G; Stascheck, A; Strauch, S; Ryckebusch, J; Carter, J;
Indirizzi:
Tech Univ Darmstadt, Inst Kernphys, D-64289 Darmstadt, Germany Tech Univ Darmstadt Darmstadt Germany D-64289 D-64289 Darmstadt, Germany State Univ Ghent, Dept Subatom & Radiat Phys, B-9000 Ghent, Belgium State Univ Ghent Ghent Belgium B-9000 Radiat Phys, B-9000 Ghent, Belgium Univ Witwatersrand, Sch Phys, ZA-2050 Johannesburg, South Africa Univ Witwatersrand Johannesburg South Africa ZA-2050 sburg, South Africa
Titolo Testata:
NUCLEAR PHYSICS A
fascicolo: 3-4, volume: 696, anno: 2001,
pagine: 293 - 316
SICI:
0375-9474(200112)696:3-4<293:GRSOCW>2.0.ZU;2-D
Fonte:
ISI
Lingua:
ENG
Soggetto:
ISOSCALAR QUADRUPOLE STRENGTH; E,E'N REACTION; COINCIDENCE EXPERIMENTS; ELECTRON-SCATTERING; MONOPOLE STRENGTH; MOMENTUM-TRANSFER; CROSS-SECTIONS; FINE-STRUCTURE; FORM-FACTORS; PB-208;
Keywords:
nuclear reaction Ca-40(e,e ' p), (e,e 'alpha), E-0,=78.183.5 MeV; measured angular correlations of p, alpha decay into low-lying states of K-39 and Ar-36; Ca-40 deduced E0, E1, E2 strength distributions, continuum;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Citazioni:
58
Recensione:
Indirizzi per estratti:
Indirizzo: von Neumann-Cosel, P Tech Univ Darmstadt, Inst Kernphys, D-64289 Darmstadt, Germany Tech Univ Darmstadt Darmstadt Germany D-64289 rmany
Citazione:
H. Diesener et al., "Giant resonance spectroscopy of Ca-40 with the (e,e ' x) reaction (II): Multipole decomposition of 4 pi-integrated spectra and angular correlations", NUCL PHYS A, 696(3-4), 2001, pp. 293-316

Abstract

The present article is the second out of three on a study of the Ca-40(e, e'x) reaction discussing the multipole decomposition of the measured cross sections and the analysis of angular correlations. The decomposition of thestrongly overlapping E0, E1 and E2 giant resonance strengths using the (e,e'x; x = p, alpha) reaction in Ca-40 is discussed for excitation energies between 10 and about 21 MeV. Two extraction methods are presented based on the variation of the form factors for the different multipoles. The resulting B(E1) strength distribution is in good agreement with (gamma, x) photoabsorption data. The summed B(E2) and B(E0) strength is highly fragmented andspread out over the energy region investigated. Microscopic continuum RPA calculations including the coupling of the basic particle-hole states to the low-lying surface vibrations are capable of reproducing the strength distributions quite accurately. Exhaustion of the energy-weighted sum rules (EWSR) for the various decay channels is presented. A complete decomposition of E0, E1 and E2 contributions in Ca-40 is possible for (e, e'alpha) angular correlations populating the Ar-36 ground state. Contrary to expectations, the form factors of isoscalar E0 and E2 strengths in the Ca-40(e, e'alpha (0)) reaction exhibit increasing differences towards smaller momentum transfers. Angular correlations for proton decay into low-lying states of K-39 are compared to a self-consistent continuum RPA calculation which allows a systematic description of the strong variations observed as a function of Ca-40 excitation energy and momentum transfer. The success implies that direct knock-out models of the Ca-40(e. e'p) reaction are too simple. Furthermore, the shapes of the angular correlations seem tobe determined largely by the final-state interaction, in particular by charge exchange reactions in the nuclear medium. (C) 2001 Elsevier Science B.V. All rights reserved.

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Documento generato il 02/04/20 alle ore 00:15:33