Measurements of Ballistic Deficits for Parallel Plate Ionization Chambers

Ionization chambers are the important gas-filled ionization detectors for heavy ion detection and spectroscopy. As the effect of ballistic deficit is the imprecision in the measurement of the pulse-height, the measurements of ballistic deficits for the pulses from ionization chambers of different types are expected to play very important role in the heavy ion spectroscopy. We have carried out measurements on the ballistic deficits for the pulses from the two-electrode parallel plate ionization chamber as well as for the pulses from the gridded parallel plate ionization chamber by processing these pulses through a simple CR-RC shaping network with pole-zero cancellation. The height of the shaped pulse versus shaping time curves for these ionization chambers show saturation at higher shaping times. Taking saturated pulse-height as the maximum possible pulse-height, the ballistic deficits have been estimated for different shaping times and are compared with the calculations based on the numerical integration method. The experimental results are in good agreement with the theoretical predictions, showing clearly that the ballistic deficits can be made negligibly small by choosing the shaping time about four-times the maximum electron collection time.