Effect of timing non-linearity of position signal on the output of linear discharge type analogue charge division

Linear Discharge Type Analogue Charge Division is a method of determining the position of ionization in the Single Wire Position Sensitive Proportional Counter (SWPC). The division output is proportional to the position of ionization where the numerator input is the pulse (V1) taken from the one end of the anode and the denominator input is the sum of the pulse (V1 + V2) taken from both ends. There exists a difference between the timing of the peak of the numerator and denominator input pulses which varies with the position and shows a non-linear characteristic. As the peak-hold gate signal of the analogue charge division is obtained from the denominator input pulse, the effect is reflected on the output of the charge division. The timing non-linearity of the input signal and the ultimate position output non-linearity are estimated analytically. The effect is evaluated for various parameters, such as, the intrinsic time constant of SWPC, the shaping time constant and gate signal's delay etc. The position output for a 1.8 m long (15 μmφ) SWPC has been obtained experimentally and the observed output non-linearity is presented and compared with the estimation. (author)