The sensitivity of accelerator mass spectrometry is mainly limited by the interferences from isobars, isotopes and other nuclides. It's difficult to online discriminate the nuclides of interest from the experimental spectra in the measurement of heavy nuclides with high backgrounds. In order to solve this problem, a programwas written for designing the experiment conditions and providing the calculated spectra. Mass numbers (M), charge states (q) and total energies (E_T) for the ions possibly entering into the detector can be output from the program. The above parameters for possible molecular ions at the ion source can also be calculated. The optimal experimental parameters can be decided by comparing the outputs with different conditions. The energy loss values of the particles entering into the detectors can be calculated by the Srim2003. Alpha particles of ²⁴¹Am were used for energy calibration of the detector. By inputting the calculated values of energy losses and residual energies of the interested ions and backgrounds the single dimensional and two-dimensional spectra can be simulated. It's helpful to analyze the experimental spectra and online discriminate the nuclides.  

Satisfactory agreement has been obtained between calculated and experimental results for ²⁶Al, ³⁶Cl, ⁴¹Ca and ⁹⁹Tc on HI-13 AMS system.