Excitation of Multipolar Transitions in Nuclei by Twisted Photons

An explicit expression for the probability of twisted-photon absorption by an atomic nucleus is obtained. It is found that photoabsorption by nuclei lying in the vicinity of the axis along which a twisted photon propagates obeys the selection rule \(j\geqslant|m_{\gamma}|\) , where \(m_{\gamma}\) is the projection of the photon total angular momentum and \(j\) is the multipolarity of the nuclear transition. In the long-wavelength limit, the \(j=|m_{\gamma}|\) multipole transition makes a dominant contribution to the probability for twisted-photon absorption. The absorption coefficient for twisted photons is found for a target that consists of many nuclei.