Since the efficiency to reconstruct a φ depends on the φ momentum, differences between the momentum spectrum in **data** and the generated spectrum in the Monte Carlo sample must be considered. Therefore, the analysis was carried out separately in 16 bins of φ momentum. The bins are chosen to have equal (with the exception of the lowest momentum range) numbers of reconstructed φ mesons in the Monte Carlo. Figure 3 shows the efficiency ε 2T as a function of the φ momentum. 