In this paper we analyze the production of high energy synchrotron gamma photons in laser-plasma interaction for a laser intensity in 1022– and a near-critical density target using two dimensional particle-in-cell simulations. In the optimum configuration to maximize the conversion efficiency of the laser energy to γ-photons, we studied the production of electron–positron pairs by the linear Breit–Wheeler process in the collision of two identical γ-photon beams using a dedicated photon-photon collision simulation code. A maximum laser energy conversion coefficient of in high energy photons was obtained and a photon beam intensity, with energies above , of at distance from the initial position of the target (for the highest laser intensity considered). We show that the optimum case to detect the linear Breit–Wheeler pairs corresponds to a laser intensity of . Our results can be used for the preparation of experimental campaigns for the detection of linear Breit–Wheeler pairs at the Apollon and ELI laser facilities.