Production of pionic atoms in the (d, 3He) reaction

The traditional methods of measuring the characteristics of pionic atoms by detecting the photons produced after the cascade transitions from higher-lying to lower-lying orbits have obvious limitations for medium and heavy nuclei, where the probability of nuclear absorption becomes much larger than the probability of the radiative transition. For example, for the 208Pb nucleus, states deeper than 3d and 4f are no longer measurable by the traditional methods. On the other hand, according to the majority of modern optical potentials, the widths of such levels are much smaller than the separation between them. Therefore, in principle, such states could exist, and their detection would be very important for the investigation of the microscopic nature of the pion-nucleus optical potential, since the characteristics of these levels are much more sensitive to the subtle details of the optical potential than, for example, the process of low-energy pion-nucleus scattering. Here the authors consider the deuteron interactions as a way to excite such states. The deuteron has the advantage of carrying a neutron, and being able to be delivered to the target with well known energy. In this paper the authors study the above reaction on 40Ca