Measured time evolutions of normalized numbers (n_x(t)/n_Σ0) of N⁺, NH⁺, NH, NH, NH, and H ions in the trap filed with He/H₂ gas mixture after the injection of N⁺ ions from the SIS. The collisional temperature is T = 16 K, hydrogen number density is [H₂]=5.7 × 10¹⁰ cm⁻³ and helium number density is [He]=5.6 × 10¹³ cm⁻³. The fitted solution of the corresponding system of rate equations is indicated with the solid lines. The crosses (x) indicate the sum of the normalized numbers (Σ(t)) of all ions in the ion trap.