Local Alfvén wave (LAW) resonances are excited in tokamaks by an externally driven electro-magnetic field, below the ion cyclotron frequency. Based on TCABR (Tokamak Chauffage Alfv´en Br´esilien) experiments and numerical calculations, it is shown that a combination of small power deposition in LAWresonances, swept by plasma density variation or scanned by varying generator frequencies, in combination with detection of the density fluctuations in the LAW resonances by reflectometry, can serve as a diagnostic tool for identification of the effective ion mass number Aef and q-profile in tokamaks. The idea is based on the simultaneous detection of the position of m = ±1 LAW resonances, which are excited by M/N = ±1/ ± 2 antenna modes and m = 0 generated by the poloidal mode coupling effect in tokamaks. The m = 0 resonance depends only on the effective ion mass number and not on the q-profile, so that the mass number can be determined unambiguously. Then, we can determine q-factor at the position of m = ±1 LAW resonances. Using the multifluid ALTOK code, we identify mass number in TCABR experiments and demonstrate the possibility of applying this method in the Joint European Torus.