Low-energy isoscalar quadrupole strength in 40Ca and 48Ca from (p,p′x) reactions

Schweda, K.; Carter, J.; Cowley, A.A.; Diesener, H.; Fearick, R.; Förtsch, S. V.; Lawrie, J. J.; Neumann-Cosel, P. von; Pilcher, J. V.; Richter, A.; Smit, F. D.; Steyn, G. F.; Strauch, S.

doi:10.1016/s0370-2693(01)00230-1

Cited by 19 publications

(7 citation statements)

References 21 publications

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“…1 taken at θ Lab = 11 • , which corresponds to the maximum cross section for the ISGQR, reveals a broad resonance at a mean energy E x ≈ 18 MeV with strength distributed between approximately 12 and 22 MeV. Intermediate structure is visible through peaks around 12, 14, 16, 17 and 18 MeV consistent with previous experimental work [5,[16][17][18]. Pronounced fine structure is observed up to about 20 MeV.…”

Section: Methodssupporting

confidence: 87%

“…These experiments were motivated by the question whether collective damping remains the most important decay mechanism in light nuclei or whether other contributions like direct decay or Landau damping become more important [15]. The present work focuses on the case of 40 Ca where considerable fragmentation of E2 strength has been observed in electron [5], proton [16,17] and alpha scattering [18] studies, albeit measured with varying resolution. The choice of a doubly magic nucleus allows a comparison to calculations within the framework of RPA and SRPA and thus to distinguish between the role of 1p-1h and 2p-2h excitations.…”

Section: Introductionmentioning

confidence: 99%

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Fine structure of the isoscalar giant quadrupole resonance in 40Ca due to Landau damping?

et al. 2011

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The fragmentation of the Isoscalar Giant Quadrupole Resonance (ISGQR) in 40 Ca has been investigated in high energy-resolution experiments using proton inelastic scattering at E p = 200 MeV. Fine structure is observed in the region of the ISGQR and its characteristic energy scales are extracted from the experimental data by means of a wavelet analysis. The experimental scales are well described by Random Phase Approximation (RPA) and second-RPA calculations with an effective interaction derived from a realistic nucleon-nucleon interaction by the Unitary Correlation Operator Method (UCOM). In these results characteristic scales are already present at the mean-field level pointing to their origination in Landau damping, in contrast to the findings in heavier nuclei and also to SRPA calculations for 40 Ca based on phenomenological effective interactions, where fine structure is explained by the coupling to two-particle two-hole (2p-2h) states.

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Section: Methodssupporting

confidence: 87%

Section: Introductionmentioning

confidence: 99%

Fine structure of the isoscalar giant quadrupole resonance in 40Ca due to Landau damping?

et al. 2011

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“…Recently, the comparison of our calculations for the low-energy isoscalar E2 strength in 40 Ca (in the 10-18 MeV interval) and 48 Ca (in the 11-14 MeV interval) with the strength that was extracted from (p, p ′ x) reactions (x = α 0 , p 0 and n 0 ) has been performed in ref. [138]. In order to do this the authors multiplied the calculated E2 strength by the ground state branching ratios deduced from statistical model calculations.…”

Section: Camentioning

confidence: 99%

Extended theory of finite Fermi systems: collective vibrations in closed shell nuclei

Kamerdzhiev¹,

Speth²,

Tertychny³

2004

Physics Reports

175

213

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We review an extension of Migdal's Theory of Finite Fermi Systems which has been developed and applied to collective vibrations in closed shell nuclei in the past ten years. This microscopic approach is based on a consistent use of the Green function method. Here one considers in a consistent way more complex 1p1h⊗phonon configurations beyond the RPA correlations. Moreover, these configurations are not only included in the excited states but also explicitly in the ground states of nuclei. The method has been applied to the calculation of the strength distribution and transition densities of giant electric and magnetic resonances in stable and unstable magic nuclei. Using these microscopic transition densities, cross sections for inelastic electron and alpha scattering have been calculated and compared with the available experimental data. The method also allows one to extract in a consistent way the magnitude of the strength of the various multipoles in the energy regions in which several multipoles overlap. We compare the microscopic transition densities, the strength distributions and the various multipole strengths with their values extracted phenomenologically.

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“…The spectra, already discussed in Ref. [20], exhibit a broad bump (roughly between 12 and 22 MeV) peaking around 18 MeV for scattering angles θ Lab = 11 [21][22][23]. At the smaller scattering angle θ Lab = 7 • , the maximum cross section is shifted to about 17 MeV, and the fine structure changes considerably indicating the presence of other multipoles.…”

Section: Methodsmentioning

confidence: 57%

“…Recently, these studies have been extended to the low-mass region 12 ≤ A ≤ 40 [19,20]. The present work focuses on the case of 40 Ca where highly fragmented E2 strength has been observed with a variety of probes including inelastic electron [21], proton [22] and α [23] scattering.…”

Section: Methodsmentioning

confidence: 99%

Level density of 2+ states in 40Ca from high energy-resolution (p,p') experiments

Usman,

Buthelezi,

Carter

et al. 2011

Preprint

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The level density of 2 + states in 40 Ca has been extracted in the energy region of the isoscalar giant quadrupole resonance (ISGQR) from a fluctuation analysis of high energy-resolution (p, p ′ ) data taken at incident energies of 200 MeV at the K600 magnetic spectrometer of iThemba LABS, South Africa. Quasi-free scattering cross sections were calculated to estimate their role as a background contribution to the spectra and found to be small. The shape of the background was determined from the discrete wavelet transform of the spectra using a biorthogonal wavelet function normalized at the lowest particle separation threshold. The experimental results are compared to widely used phenomenological and microscopic models.

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Low-energy isoscalar quadrupole strength in 40Ca and 48Ca from (p,p′x) reactions

Cited by 19 publications

References 21 publications

Fine structure of the isoscalar giant quadrupole resonance in 40Ca due to Landau damping?

Fine structure of the isoscalar giant quadrupole resonance in 40Ca due to Landau damping?

Extended theory of finite Fermi systems: collective vibrations in closed shell nuclei

Level density of 2+ states in 40Ca from high energy-resolution (p,p') experiments

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