  We propose a new method of generating gamma rays with orbital angular
momentum (OAM). Accelerated partially-stripped ions are used as an energy
up-converter. Irradiating an optical laser beam with OAM on ultrarelativistic
ions, they are excited to a state of large angular momentum. Gamma rays with
OAM are emitted in their deexcitation process. We examine the excitation cross
section and deexcitation rate.
