Elastic photonuclear cross sections for bremsstrahlung from relativistic ions

NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION B-BEAM INTERACTIONS WITH MATERIALS AND ATOMS

卷:372

Article

Mikkelsen, Rune E.¹  Sorensen, Allan H.¹  Uggerhoj, Ulrik I.¹ 

[1] Aarhus Univ, Dept Phys & Astron, DK-8000 Aarhus C, Denmark

关键词: Bremsstrahlung;    Atomic collisions;    Fixed target;    Nuclear models;    Virtual photons;   

DOI  :  10.1016/j.nimb.2016.02.003

来源: Elsevier

【 摘 要 】

In this paper, we provide a procedure to calculate the bremsstrahlung spectrum for virtually any relativistic bare ion with charge 6e or beyond, Z >= 6, in ultraperipheral collisions with target nuclei. We apply the Weizsacker-Williams method of virtual quanta to model the effect of the distribution of nuclear constituents on the interaction of the ion with the radiation target. This leads to a bremsstrahlung spectrum peaking at 2 gamma times the energy of the giant dipole resonance (gamma is the projectile energy in units of its rest energy). A central ingredient in the calculation is the cross section for elastic scattering of photons on the ion. This is only available in the literature for a few selected nuclei and, usually, only in a rather restricted parameter range. Hence we develop a procedure applicable for all Z greater than or similar to 6 to estimate the elastic scattering. The elastic cross section is obtained at low to moderate photon energies, somewhat beyond the giant dipole resonance, by means of the optical theorem, a dispersion relation, and data on the total absorption cross section. The cross section is continued at higher energies by invoking depletion due to loss of coherence in the scattering. Our procedure is intended for any ion where absorption data is available and for moderate to high energies, gamma greater than or similar to 10. (C) 2016 Elsevier B.V. All rights reserved.

【 授权许可】

Free