A possible way of using two-photon very forward production of positron--electron pairs for a luminosity measurement of ion collisions at the LHC is discussed. The main characteristics of this process are introduced, and followed by results from fast Monte Carlo simulations of the measurement using the proposed Castor detector. The statistical accuracy of this method is discussed for the considered LHC ion beams.

PACS numbers: 13.40.--f, 25.75.--q, 29.27.--a