Absorption and scattering of photons by 208Pb

Compton scattering cross sections from 6 Li have been measured at scattering angles of 40• -160• using a nearly monoenergetic 60 MeV photon beam at the High Intensity Gamma-Ray Source (HI γS). This represents the first precision measurement of Compton scattering on 6 Li. A phenomenological model provides an estimate of the sensitivity of the 6 Li(γ,γ) 6 Li cross section to the nucleon isoscalar electromagnetic polarizabilities αs and βs.

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“…where the complex forward scattering amplitudes f λ (E) (λ = E1, E2, QD) are taken to have a Lorentzian form [32] given by…”

Section: Phenomenological Modelmentioning

confidence: 99%

Compton scattering from6Li at 60 MeV

et al. 2012

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“…Several experiments on Compton scattering by nuclei were concerned with multipole decompositions of giant resonances [13,15,16,18,19,21,25,26,30,33,64]. The comparatively weak electric quadrupole amplitude is enhanced through interference with the dominant electric-dipole amplitude.…”

Section: Motivations For Studying Nuclear Compton Scatteringmentioning

confidence: 99%

“…For the analysis of Compton scattering data it is most convenient to use a Lorentzian representation as proposed by Ziegler [15].…”

Section: Further Properties Of Quasideuteronsmentioning

confidence: 99%

“…π V dp 1 dp 2 (2π) 6 15) where r = p 1 −p 2 −Q and V is the nuclear volume. The function n(p) = θ(p F −|p |) is the occupation number in the Fermi gas model.…”

Section: Corrections To the Correlation Functionmentioning

confidence: 99%

“…What does is a projection to positive-energy states. 15 In other words, we consider the t-derivative of the invariant amplitude A1. Cf.…”

Section: Retarded and Unretarded Sum Rulesmentioning

confidence: 99%

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Compton scattering by nuclei

et al. 2000

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The concept of Compton scattering by even-even nuclei from giant-resonance to nucleon-resonance energies and the status of experimental and theoretical researches in this field are outlined. The description of Compton scattering by nuclei starts from different complementary approaches, namely from second-order S-matrix and from dispersion theories. Making use of these, it is possible to incorporate into the predicted nuclear scattering amplitudes all the information available from other channels, viz. photon-nucleon and photon-meson channels, and to efficiently make use of models of the nucleon, the nucleus and the nucleon-nucleon interaction. The total photoabsorption cross section constrains the nuclear scattering amplitude in the forward direction. The specific information obtained from Compton scattering therefore stems from the angular dependence of the nuclear scattering amplitude, providing detailed insight into the dynamics of the nuclear and nucleon degrees of freedom and into the interplay between them. Nuclear Compton scattering in the giant-resonance energy-region provides information on the dynamical properties of the in-medium mass of the nucleon. Most prominently, the electromagnetic polarizabilities of the nucleon in the nuclear medium can be extracted from nuclear Compton scattering data obtained in the quasideuteron energy-region. In our description of this latter process special emphasis is laid upon the exploration of many-body and two-body effects entering into the nuclear dynamics. Recent results are presented for two-body effects due to the mesonic seagull amplitude and due to the excitation of nucleon internal degrees of freedom accompanied by meson exchanges. Due to these studies the inmedium electromagnetic polarizabilities are by now well understood, whereas the understanding of nuclear Compton scattering in the ∆-resonance range is only at the beginning. Furthermore, phenomenological methods how to include retardation effects in the scattering amplitude are discussed and compared with model predictions.

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