Coherent Coulomb excitation of relativistic nuclei in aligned crystal targets

Abstract

We study coherent Coulomb excitation of ultrarelativistic nuclei passing through the aligned crystal target. We develop multiple scattering theory description of this process which consistently incorporates both the specific resonant properties of particle-crystal interactions and the shadowing effect typical of the diffractive scattering. We emphasise that the effect of quantum mechanical diffraction makes the physics of ultrarelativistic nuclear excitations entirely different from the physics of non-relativistic atomic excitations experimentally studied so far. It is found that at small transverse momenta $q_{\perp}$ the shadowing effect drastically changes the dependence of coherent amplitudes on the crystal thickness $L$, from the widely discussed growth $\propto L$ typical of the Born approximation to the inverse thickness attenuation law. At relatively large $q_{\perp}$ no attenuation effect is found but the coherency condition is shown to put stringent constrain on the growth of the transition rate with growing $L$.