Eur. Phys. J. A (2004) 22: 347-351
https://doi.org/10.1140/epja/i2004-10098-4

Surface and volume effects in the photoabsorption of nuclei

¹ Department of Physics and Astronomy, University of Basel, CH-4056, Basel, Switzerland
² Institut für Theoretische Physik I, Universität Giessen, D-35392, Giessen, Germany
³ II. Physikalisches Institut, Universität Giessen, D-35392, Giessen, Germany

^* e-mail: Bernd.Krusche@unibas.ch

Received: 27 September 2004
Accepted: 3 November 2004
Published online: 11 November 2004

Abstract

Recent experimental results for meson photoproduction from nuclei obtained with TAPS at MAMI are analyzed in view of the suppression of the second nucleon resonance region in total photoabsorption. The cross-sections can be split into a component from the low-density surface region of nuclei and a component which scales more like the nuclear volume. The energy dependence of the surface component is similar to the deuteron cross-section, it shows a clear signal for the second resonance peak assigned to the excitation of the P₁₁(1440), D₁₃(1520), and S₁₁(1535). The volume component behaves differently, it is lacking the second resonance peak and shows an enhancement at intermediate photon energies.