ϕ photo-production from Li, C, Al, and Cu nuclei at Eγ=1.5-2.4GeV

The photo-production of ϕ mesons from Li, C, Al, and Cu at forward angles has been measured at Eγ=1.5-2.4GeV. The number of events for incoherent ϕ photo-production is found to have a target mass number dependence of A0.72±0.07 in the kinematical region of |t|⩽0.6GeV2/c2. The total cross section of the ϕ-nucleon interaction, σϕN, has been estimated as 35−11+17mb using the A-dependence of the ϕ photo-production yield and a Glauber-type multiple scattering theory. This value is much larger than σϕN in free space, suggesting that the ϕ properties might change in the nuclear medium.