Electromagnetic dissociation of nuclei in heavy-ion collisions

Cj, Benesh; Jl, Friar

doi:10.1103/physrevc.48.1285

Cited by 8 publications

(14 citation statements)

References 29 publications

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“…Here R T is the target charge radius, and C ℓ is a constant chosen so as to saturate the appropriate photonuclear sum rule for multipole ℓ [10]. In the shell model, appropriate linear combinations of the single-particle transitions can provide descriptions of either giant resonance states or non-collective states.…”

Section: Target Structure Effectsmentioning

confidence: 99%

Quantum-mechanical equivalent-photon spectrum for heavy-ion physics

1996

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In a previous paper, we calculated the fully quantum-mechanical cross section for electromagnetic excitation during peripheral heavy-ion collisions. Here, we examine the sensitivity of that cross section to the detailed structure of the projectile and target nuclei. At the transition energies relevant to nuclear physics, we find the cross section to be weakly dependent on the projectile charge radius, and to be sensitive to only the leading momentum-transfer dependence of the target transition form factors. We exploit these facts to derive a quantum-mechanical "equivalent-photon spectrum" valid in the long-wavelength limit. This improved spectrum includes the effects of projectile size, the finite longitudinal momentum transfer required by kinematics, and the response of the target nucleus to the off-shell photon.In the previous decade, relativistic heavy-ion beams have become a useful tool for the study of electromagnetic processes in nuclei. Applications have included studies of nuclear astrophysics[1], nuclei far from stability [2], and searches for multi-phonon excitations in nuclei [3]. In these experiments, cross sections that are difficult to measure by other means are amplified by the projectile charge, and, in the case of relativistic projectiles, by the contraction of the projectile's electric field into a sharp pulse.Almost exclusively, the data from these experiments have been analyzed using the semiclassical Weizsäcker-Williams method of virtual quanta [4], in which the cross section for the heavy-ion-induced reaction is calculated by integrating the cross section for the analogous real-photon process over a flux of photons that is "equivalent" to those that make up the electric field of the projectile. In its simplest form, the pulse of equivalent photons is obtained from the boosted Coulomb field of the projectile by equating the classical Poynting flux onto the target to the energy flux carried by the pulse of equivalent photons. The semi-classical spectrum has been generalized to include arbitrary multipoles[5], projectile structure [6] and Coulomb scattering effects [7]. Attempts to move beyond the semi-classical picture of these processes have been thwarted by lack of information about the structure of the target nucleus [8]. Furthermore, there has been little motivation for improvement because the semi-classical spectrum, when used in conjunction with data from real-photon processes, provides model-independent results for cross sections measured in heavy-ion collisions [9].Recently, we have undertaken a program to systematically examine corrections to the semi-classical picture[10] [11], and have found significant deviations from the predictions of the Weizsäcker-Williams method for the mildly relativistic collisions (γ < 2 − 3) that constitute a significant fraction of the available data. The aim of the present work is to expand on the results of reference 10, examining the sensitivity of the cross section to nuclear structure inputs. Having determined which inputs are essential to extracting...

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Section: Target Structure Effectsmentioning

confidence: 99%

Quantum-mechanical equivalent-photon spectrum for heavy-ion physics

1996

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“…Consequently, we work in configuration space, where expansions in R are easiest, using techniques introduced in electromagnetically-induced heavy-ion reactions [18]. Similar techniques were used in Refs.…”

Section: Appendix Amentioning

confidence: 99%

“…The inelastic charge density (squared) can be rewritten in cases where there are no energy factors [18] …”

Section: Higher Polarizabilitiesmentioning

confidence: 99%

Higher-order nuclear-polarizability corrections in atomic hydrogen

Friar

Payne

1997

Phys. Rev. C

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Nuclear-polarizability corrections that go beyond unretarded-dipole approximation are calculated analytically for hydrogenic (atomic) S-states. These retardation corrections are evaluated numerically for deuterium and contribute -0.68 kHz, for a total polarization correction of 18.58(7) kHz. Our results are in agreement with one previous numerical calculation, and the retardation corrections completely account for the difference between two previous calculations. The uncertainty in the deuterium polarizability correction is substantially reduced. At the level of 0.01 kHz for deuterium, only three primary nuclear observables contribute: the electric polarizability, α E , the paramagnetic susceptibility, β M , and the third Zemach moment, r 3 (2) . Cartesian multipole decomposition of the virtual Compton amplitude and its concomitant gauge sum rules are used in the analysis.

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“…With allowance for the difference in the target mass number, this estimate is consistent with data from [25], where the electromagnetic contribution to the cross section for the reaction 197 Au( 12 C, x) 196 Au was estimated at 66 ± 20 mb, and with the theoretical estimates obtained in [33] for the yield of 196 Au in the 12 С+ 197 Au reaction, the calculations there being performed on the basis of two models (51 and 40 mb).…”

Section: Electromagnetic Excitation Of Target Nucleimentioning

confidence: 86%

Formation of close-to-target products in reactions induced by 12C ions on tin isotopes at the energy of 2.2 GeV per nucleon

et al. 2012

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Cross sections for charge-exchange reactions induced by the interaction between 12 C ions of energy E12 C = 2.2 GeV per nucleon and tin targets enriched in the isotopes 118,120,124 Sn were measured by the induced-activity method. The cross sections for products whose charge numbers were in excess of the target charge number (Sb and Te) were determined. The shape of the isotope distribution of Sb products was indicative of the evaporative character of neutron emission in the formation of final-state products. The dependence of cross sections for charge-exchange reactions on the nucleonic composition of the target was considered. The contribution of electromagnetic excitation to the cross section for the reaction 124 Sn( 12 C, x) 124 Sn was estimated.

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Electromagnetic dissociation of nuclei in heavy-ion collisions

Cited by 8 publications

References 29 publications

Quantum-mechanical equivalent-photon spectrum for heavy-ion physics

Quantum-mechanical equivalent-photon spectrum for heavy-ion physics

Higher-order nuclear-polarizability corrections in atomic hydrogen

Formation of close-to-target products in reactions induced by 12C ions on tin isotopes at the energy of 2.2 GeV per nucleon

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