Inclusive measurements of electromagnetic dissociation of<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mmultiscripts><mml:mrow><mml:mi mathvariant="normal">Au</mml:mi></mml:mrow><mml:mprescripts /><mml:mrow /><mml:mrow><mml:mn>197</mml:mn></mml:mrow><mml:mrow /><mml:mrow /></mml:mmultiscripts></mml:mrow></mml:math>targets

Aumann, T.; Kratz, J. V.; Stiel, E.; Sümmerer, K.; Brüchle, W.; Schädel, M.; Wirth, G.; Fauerbach, M.; Hill, J. C.

doi:10.1103/physrevc.47.1728

Cited by 65 publications

(81 citation statements)

References 20 publications

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“…This parametrization has been used previously [41] and a reasonable agreement with the measured data for 1n cross sections was found. It should be noted, however, that the Kox parametrization of total interaction cross sections has been derived mainly from experiments with light projectiles and that its application to heavy systems involves an extrapolation into a region where no data points are available.…”

Section: Nucleon Removal In Peripheral Relativistic Heavy Ion Collisionssupporting

confidence: 55%

“…However, these corrections are small for realistic deformations. They cannot be responsible for the large deviations of the experimental values of the Coulomb fragmentation cross sections from the standard theory [6,18], as has been observed [41,49] for deformed projectiles.…”

Section: Excitation By a Deformed Nucleusmentioning

confidence: 80%

“…The dotted lines are obtained by using the non-relativistic Eq. (94), while the dashed lines correspond to the relativistic expressions (41,42,43). One observes that the relativistic expressions overestimate the equivalent photon numbers at low energies, while the non-relativistic expressions underestimate them at high energies.…”

Section: Comparison Of Coulomb Excitation Of Gr's At Low Energies Andmentioning

confidence: 99%

“…Since all nuclear excitation dynamics is contained in the photoabsorption cross section, the virtual photon numbers (41,42,43) do not depend on the nuclear structure. They are kinematical factors, depending on the orbital motion.…”

Section: Excitation Probabilities and Virtual Photon Numbersmentioning

confidence: 99%

“…It is assumed that below this minimum value the interaction is exclusively due to the strong interaction ("sharp-cutoff" approximation). It has been found that with this approximation the Coulomb cross sections are very sensitive to the parameterization of the minimum impact parameter [39,40,41,42].…”

Section: Nucleon Removal In Peripheral Relativistic Heavy Ion Collisionsmentioning

confidence: 99%

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Microscopic studies of two-phonon giant resonances

Ponomarev

1999

Nuclear Physics A

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A new class of giant resonances in nuclei, namely double giant resonances, is discussed. They are giant resonances built on top of other giant resonances. Investigation on their properties, together with similar studies on low-lying two-phonon states, should give an answer on how far the harmonic picture of boson-type excitations holds in the finite fermion systems like atomic nuclei.The main attention in this review is paid to double giant dipole resonances (DGDR) which are observed in relativistic heavy ion collisions with very large cross sections. A great experimental and theoretical effort is underway to understand the reaction mechanism which leads to the excitation of these states in nuclei, as well as the better microscopic understanding of their properties. The Coulomb mechanism of the excitation of single and double giant resonances in heavy ion collision at different projectile energies is discussed in details. A contribution of the nuclear excitation to the total cross section of the reaction is also considered. The Coulomb excitation of double resonances is described within both, the second-order perturbation theory approach and in coupled-channels calculation. The properties of single and double resonances are considered within the phenomenologic harmonic vibrator model and microscopic quasiparticle-RPA approach. For the last we use the Quasiparticle-Phonon Model (QPM) the basic ideas and formalism of which are presented. The QPM predictions of the DGDR properties (energy centroids, widths, strength distributions, anharmonicities and excitation cross sections) are compared to predictions of harmonic vibrator model, results of other microscopic calculations and experimental data available. : 24.30.Cz, 25.70.De, Pacs

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Section: Nucleon Removal In Peripheral Relativistic Heavy Ion Collisionssupporting

confidence: 55%

Section: Excitation By a Deformed Nucleusmentioning

confidence: 80%

Section: Comparison Of Coulomb Excitation Of Gr's At Low Energies Andmentioning

confidence: 99%

Section: Excitation Probabilities and Virtual Photon Numbersmentioning

confidence: 99%

Section: Nucleon Removal In Peripheral Relativistic Heavy Ion Collisionsmentioning

confidence: 99%

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Microscopic studies of two-phonon giant resonances

Ponomarev

1999

Nuclear Physics A

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Multiphonon and “Hot”-Phonon Isovector Electric-Dipole Excitations

et al. 1999

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We argue that a substantial increase in the cross section for Coulomb excitation in the region of the Double Giant Dipole Resonance should be expected from Coulomb excitation of excited states involved in the spreading of the one-phonon resonance, in a manifestation of the Brink-Axel phenomenon. This generates an additional fluctuating amplitude and a corresponding new term to be added incoherently to the usual cross-section. The appropriate extension of an applicable reaction calculation is considered in order to estimate this effect. [4][5][6]. The isoscalar double giant quadrupole resonance has also been observed in the proton emission spectrum from the collision of 40 Ca with 40 Ca at a laboratory energy of 44 A Mev [7].When the data on DGDR excitation for 136 Xe and 197 Au are compared with coupled-channel Coulomb excitation calculations [8], it is found that, in the harmonic approximation, the calculated cross sections are a factor of 2 to 3 smaller than the measured ones. A similar discrepancy, albeit somewhat smaller, is found for 208 Pb.Several effects that are not taken into account in the coupled-channel theory have been considered as possible explanations of this discrepancy. As examples, we mention the effect of anharmonicities [9,10] and the quenching of the 1 + DGDR state [11]. Here we will consider a new potentially important mechanism, which consists in the (one phonon) Coulomb excitation of backgrount states responsible for the large spreading width of the one-phonon GDR, as suggested long ago by Brink and Axel [12]. Due to the complicated background of intrinsic states, the amplitude for this process varies rapidly wth energy and possesses an average close to zero. Its contribution to the cross section can be sizable, however. In close analogy to this situation is the the well-known case of nucleon-nucleus elastic scattering. There, the cross section is the sum of the slowly-varying contribution of average optical scattering and of the fluctuating contribution compound nucleus formation and decay. In figure 1 we show a schematic picture of the couplings involved.We first sumarize our main result. The cross-section for Coulomb excitation to the DGDR energy region contains in fact two distinct components which peak at ∼ 2E GDR . However, while the usual component σ DGDR has a width which may be estimated as ∼ 2Γ GDR , the fluctuating Brink-Axel component has a width which is just ∼ Γ GDR . As a result of this, the bump observed in the two-phonon region has an effective width between these limits. The enhancement factor for the peak-value of the cross-section will be given roughly by (1 + Γ ↓ 1 /Γ 1 ), whereas the crosssection integrated over the peak is just about (1 + 1 2 Γ ↓ 1 /Γ 1 )σ DGDR due to the smaller width of the second component. For heavy nuclei Γ ↓ 1 ∼ Γ 1 , and we get enhancement factors of ∼ 2 and ∼ 3/2 for the peak and for the integrated crosssections respectively. Furthermore, these enhancement factors should be reduced and tend to unity as the collision time becomes shorter t...

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Electromagnetic and nuclear fission of238U in the reaction of 100, 500, and 1000 A�MeV208Pb with238U

Polikanov

Brüchle

Folger

et al. 1994

Z. Physik A - Hadrons and Nuclei

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Abstract. The folding-and azimuthal-angle and velocity distributions for the Z3Su fission fragments have been measured in reactions with 100, 500, and 1000A.MeV 2~ These distributions were used to decompose the fission cross section into its electromagnetic and nuclear components. The fraction of electromagnetic fission was found to be 0.16-t-0.07, 0.48• and 0.60• respectively. The electromagnetic fission cross section as a function of the 2~ nucleus energy is compared with theoretical predictions. The measured fission cross section from nuclear reactions (~ 1.5 b) is approximately constant between 100 and 1000 A.MeV. 25.85.-w; 25.70.-z PACS:

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Inclusive measurements of electromagnetic dissociation ofAu197targets

Cited by 65 publications

References 20 publications

Microscopic studies of two-phonon giant resonances

Microscopic studies of two-phonon giant resonances

Multiphonon and “Hot”-Phonon Isovector Electric-Dipole Excitations

Electromagnetic and nuclear fission of238U in the reaction of 100, 500, and 1000 A�MeV208Pb with238U

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